Abstract THE PRODUCTION OF PROBABILISTIC ENTROPY IN STRUCTUREACTION CONTINGENCY RELATIONS

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朋友关系的存续是以相互尊重为前提的

朋友关系的存续是以相互尊重为前提的, 容不得半点强求、干涉和控制。

朋友之间, 情趣相投、脾气对味则合、则交; 反之, 则离、则绝。

朋友之间再熟悉, 再亲密, 也不能随便过头，不恭不敬。

不然，默契和平衡将被打破, 友好关系将不复存在。

每个人都希望拥有自己的私密空间，朋友之间过于随便，就容易侵入这片禁区，从而引起冲突，造成隔阂。

待友不敬，或许只是一件小事，却可能已埋下了破坏性的种子。

维持朋友亲密关系的最好办法是往来有节，互不干涉。

I thought that it was a Sunday morning in May; that it was Easter Sunday, and as yet very early in the morning. I was standing at the door of my own cottage. Right before me lay the very scene which could really be commanded from that situation, but exalted, as was usual, and solemnized by the power of dreams. There were the same mountains, and the same lovely valley at their feet; but the mountains were raised to more than Alpine height, and there was interspace far larger between them of meadows and forest lawns; the hedges were rich with white roses; and no living creature was to be seen except that in the green churchyard there were cattle tranquilly reposing upon the graves, and particularly round about the grave of a child whom I had once tenderly loved, just as I had really seen them, a little before sunrise in the same summer, when that child died.So far as we can tell, all human languages are equally complete and perfect asinstruments of communication: that is, every language appears to be well equipped as any other to say the things their speakers want to say.There may or may not be appropriate to talk about primitive peoples or cultures, but that is another matter. Certainly, not all groups of people are equally competent in nuclear physics or psychology or the cultivation of rice or the engraving of Benares brass. Whereas this is not the fault of their language. The Eskimos can speak about snow with a great deal more precision and subtlety than we can in English, but this is not because the Eskimo language (one of those sometimes miscalled 'primitive') is inherently more precise and subtle than English. This example does not come to light a defect in English, a show of unexpected 'primitiveness'. The position is simply and obviously that the Eskimos and the English live in similar environments. The English language will be just as rich in terms for 1 2 345 6 7similar kinds of snow, presumably, if the environments in which English was habitually used made such distinction as important.Similarly, we have no reason to doubt that the Eskimo language could be as precise and subtle on the subject of motor manufacture or cricket if these topics formed the part of the Eskimos' life. For obvious historical reasons, Englishmen in the nineteenth century could not talk about motorcars with the minute discrimination which is possible today: cars were not a part of their culture. But they had a host of terms for horse-drawn vehicles which send us, puzzled, to a historical dictionary when we are reading Scott or Dickens. How many of us could distinguish between a chaise, a landau, a victoria, a brougham, a coupe, a gig, a diligence, a whisky, a calash, a tilbury, a carriole, a phaeton, and a clarence ?8 91031. Which of the following statements in INCORRECT?A. The British constitution includes the Magna Carta of 1215.B. The British constitution includes Parliamentary acts.C. The British constitution includes decisions made by courts of law.D. The British constitution includes one single written constitution.32. The first city ever founded in Canada is A. Quebec.B. V ancouver.C. Toronto.D. Montreal.33. When did the Australian Federation officially come into being?A. 1770.B. 1788.C. 1900.D. 1901.34. The Emancipation Proclamation to end the slavery plantation system in the South of the U.S. was issued by A. Abraham Lincoln.B. Thomas Paine.C. George Washington.D. Thomas Jefferson.35. ________ is best known for the technique of dramatic monologue in his poems..A. Will Blake B. W.B. Yeats C. Robert Browning D. William Wordsworth36. The Financier is written by A. Mark Twain.B. Henry James.C. William Faulkner.D. Theodore Dreiser.37. In literature a story in verse or prose with a double meaning is defined as A. allegory.B. sonnet.C. blank verse.D. Rhyme.38. ________ refers to the learning and development of a language.A. Language acquisition B. Language comprehension C. Language production D. Language instruction39. The word “ Motel” comes from “motor + hotel”. This is an example of ________ in morphology.A. BackformationB. ConversionC. BlendingD. Acronym40. Language is t tool of communication. The symbol “ Highway Closed” on a highwa y serves A. an expressive function.B. an informative function.C. a performative function.D. a persuasive function.现代社会无论价值观的持有还是生活方式的选择都充满了矛盾。

Abstract

2-Generated Cores in Groups of Finite Morley Rank of Odd TypeAlexandre V.Borovik Department of Mathematics UMIST PO Box88Manchester M601QDUnited Kingdom alexandre.borovik@Ali Nesin∗Mathematics Department Istanbul Bilgi UniversityKu¸s tepe S¸i¸s liIstanbul Turkeyanesin@.tr14July2002AbstractWe prove aﬁnal identiﬁcation theorem for the“generic”K*-groups of ﬁnite Morley rank and odd type.This gives a positive answer to one ofthe important special cases of the Cherlin-Zilber Conjecture.1IntroductionAccording to a long-standing conjecture in model theory,due to Gregory Cherlin and Boris Zilber,simple groups ofﬁnite Morley rank should be algebraic.The present paper belongs to a series of results aimed at proving the following: Odd Type Conjecture.Let G be a simple group ofﬁnite Morley rank of odd type,with no inﬁnite deﬁnable simple section of degenerate type.Then G is a simple algebraic group over an algebraically closedﬁeld of characteristic=2.See[9]for a brief informal introduction to the subject,[8]for background results on groups of odd type and[10]for further technical details on groups of ﬁnite Morley rank.An inﬁnite simple group G ofﬁnite Morley rank is said to be of odd type if its Sylow2-subgroups are inﬁnite and abelian divisible-by-ﬁnite.It is of degenerate type if its Sylow2-subgroups areﬁnite.Those who are skeptical about the Cherlin-Zilber Conjecture should expect degenerate type groups to exist.Indeed,the Odd Type Conjecture suggests that groups of degenerate type form the heart of the matter.∗Partially supported by the London Mathematical Society grant4523.0Mathematics Classiﬁcation Numbers03C60,20G991We work with a counterexample G of minimal Morley rank to the general Cherlin-Zilber Conjecture.This allows us to assume that every proper simple deﬁnable connected section of G is a simple algebraic group over an algebraically closedﬁeld.We adopt the terminology of the classiﬁcation ofﬁnite simple groups and say that G is a K*-group.Although we work with algebraic groups,we ignore their underlying alge-braic geometry and their Zariski topology;therefore it is convenient for us to refer to simple algebraic groups as Chevalley groups,that is,groups given by certain generators and relations associated with simple complex Lie algebras [13];the classiﬁcation of simple algebraic groups over an algebraically closed ﬁeld amounts to saying that such groups are Chevalley groups.1.1The Main ResultWe start with the ingredients of our main theorem.If E is an elementary abelian2-group,its2-rank m(E)is its minimal number of generators.If H is an arbitrary group,its2-rank m(H)is deﬁned as the maximum of the2-ranks of elementary abelian subgroups of H.If S is a Sylow 2-subgroup of H(i.e.a maximal2-subgroup of H),then the normal2-rank n(H) is the maximum of the2-ranks of elementary abelian normal subgroups in S.Let G be a group ofﬁnite Morley rank and of odd type.Let S be a Sylow2-subgroup of G.The deﬁnable closure of the subgroup N G(V)|V≤S,V is elementary abelian and m(V)≥2is called the2-generated core of G(associated with S)and is denoted byΓS,2(G).It can be easily seen that there are no simple algebraic groups over alge-braically closedﬁelds of characteristic not2with proper2-generated cores. (Here we understand“simple”in the sense of abstract group theory,not the theory of simple algebraic groups,where a“simple algebraic group”is allowed to have aﬁnite center.In that wider meaning of“simple”,the only simple algebraic groups with proper2-generated cores are the groups SL2(K);how-ever,these groups have centers of order2.)Thus the result that we will soon state removes an important technical obstruction from a proof of Odd Type Conjecture.The divisible abelian part of a Sylow2-subgroup of G is a direct sum of ﬁnitely many-say n-copies of the Pr¨u fer2-group Z2∞.This number n is called the Pr¨u fer2-rank of G and is denoted by pr2(G).A minimal group is a group ofﬁnite Morley rank whose proper deﬁnable subgroups are soluble-by-ﬁnite.Theorem1A simple K*-group of odd type and of Pr¨u fer2-rank≥3with a proper2-generated core is a minimal group.1.2A Corollary for Tame GroupsWhen applied to the narrower class of tame groups,Theorem1leads to a char-acterisation of“almost all”Chevalley groups in the class of groups ofﬁnite2Morley rank:Theorem2A simple K∗and tame group of odd type either has Pr¨u fer2-rank ≤2or is a Chevalley group over an algebraically closedﬁeld of characteristic =2.Notice that the only Chevalley groups not covered by this theorem are the groups PSL2,PSL3,PSp4and G2.Here,a tame group is a group ofﬁnite Morley rank that has no simple deﬁnable sections of degenerate type and that does not interpret a badﬁeld.And the latter is a ranked structure of the form K,+,·,A where K,+,· is an algebraically closedﬁeld and A is a(predicate for a)proper inﬁnite multiplicative subgroup of K∗.It is not known whether or not badﬁelds exist;however,the existence of badﬁelds of positive characteristic has been recently put in serious doubt by an unexpected result of Frank Wagner[20]:The existence of a bad ﬁeld of characteristic p>0implies theﬁniteness of p-Mersenne prime numbers (that is,prime numbers of the form(p k−1)/(p−1)for natural numbers k).Theorem2follows from a more technical result,from Theorem3below,and from a recent theorem of Cherlin and Jaligot[14]on minimal tame groups. Theorem3A simple K∗-group of odd type either is a Chevalley group over an algebraically closedﬁeld of characteristic=2,or has Pr¨u fer2-rank≤2,or is a minimal group.In its turn,Theorem3is based on Theorem1and the“generic identiﬁcation theorem”for groups ofﬁnite Morley rank[6].Its another crucial ingredient is JeﬀBurdges’theorem on signaliser functors[12].Theorem3replaces the“Trichotomy Theorem”[8,Theorem6.19]as the main case subdivision in the Odd Type Conjecture.2Deﬁnitions and FactsFrom now on G stands for a group ofﬁnite Morley rank.For x∈G,we let C x denote C G(x)◦.2.1Sylow TheoryA p⊥-group is a group without elements of order p.Fact2.1(Exercise11,p.93of[10])Let p be a prime and H G a normal deﬁnable p⊥-subgroup.Then any element of order p of G/H lifts to an element of order p of G.A Sylow2-subgroup is a maximal subgroup of G consisting of2-elements. The group G is said to be of odd type if its Sylow2-subgroups are inﬁnite and are divisible abelian-by-ﬁnite.Thus the divisible abelian part S◦of a Sylow2-subgroup S of such a group G is a nontrivial direct sum ofﬁnitely many copies3(say n)of the Pr¨u fer2-group Z2∞;the group S◦is called a Sylow◦2-subgroup or a maximal2-torus of G.The integer n is called the Pr¨u fer2-rank of G;it does not depend on choice of the Sylow2-subgroup since the Sylow2-subgroups of a group ofﬁnite Morley rank are conjugate to each other[11](see also[10, Section10.3]).Weﬁnish this subsection with two technical results on Sylow2-subgroups. Fact2.2(Lemma10.22of[10])Let S◦be a Sylow◦2-subgroup of G.Then N G(S◦)controls fusion in S◦,i.e.two subsets of S◦which are G-conjugate are in fact N G(S◦)-conjugate.Fact2.3([4])Assume G is soluble.Let N G be a deﬁnable subgroup and let S≤G be a Sylow2-subgroup.Then SN/N is a Sylow2-subgroup of G/N and all the Sylow2-subgroups of G/N are of this form.2.2The Structure of K-groupsWe deﬁne F(G),the Fitting subgroup of G,to be the subgroup generated by all the normal nilpotent subgroups of G.The subgroup F(G)is nilpotent and deﬁnable[5,17](see also[10,Theorem7.3]).We let O(G)denote the maximal normal deﬁnable connected2⊥-subgroup of G,i.e.O(G)is the maximal deﬁnable and connected subgroup of G that does not contain an involution,that is,an element of order2.The group G is called a K-group,if its simple inﬁnite deﬁnable sections are Chevalley group over an algebraically closedﬁeld,and a K*-group,if its deﬁnable proper subgroups are K-groups.The following easy result is part of the folklore:Fact2.4Let G be a K-group of odd type.Then O(G)is soluble.A group G is called quasi-simple if G=G and G/Z(G)is(necessarily nonabelian)simple.Fact2.5([5],[17],see also[10])Every quasi-simple subnormal subgroup of G is deﬁnable and normal and there are onlyﬁnitely many of them(called components of G).The subgroup generated by the components of G is therefore a setwise prod-uct of the components and is deﬁnable.It is denoted L(G)and is called the layer of G.One also deﬁnes E(G)=L(G)◦.Fact2.6Let G be a connected K-group of odd type.Then G/O(G)is iso-morphic to a central product of quasi-simple algebraic groups over algebraically closedﬁelds of characteristic=2and of an abelian group.In particular,if G=G/O(G)then G=F(G)E(G)and F(G)is an abelian group.4Proof:The“in particular”part of the statement is[8,Theorem5.9].By deﬁnition,E(G)=L1∗···∗L k is a central product of connected quasisim-ple groups.By the K-assumption,each L i is a perfect central extension of a Chevalley group over an algebraically closedﬁeld.Now the result follows from the following important fact.Fact2.7(Altınel and Cherlin[3])A group ofﬁnite Morley rank which is a perfect central extension of an algebraic group over an algebraically closedﬁeld is an algebraic group and hasﬁnite center.A four-group is a group isomorphic to Z/2Z⊕Z/2Z.Fact2.8(Theorem5.14of[8])Let G be a K-group of odd type,H a deﬁn-able subgroup of G and A<G a four-subgroup normalising H.ThenH◦= C◦H(a)|a∈A# .2.3Classiﬁcation TheoremsThe following is a direct application to the prime p=2of the identiﬁcation theorem stated and proved for arbitrary primes p in[6]:Fact2.9(Berkman and Borovik[6])Let G be a simple K*-group of odd type and of Pr¨u fer2-rank≥3.Assume that(1)G= C x|x an involution in S ,(2)For every involution x in a Sylow◦subgroup of G,C x=F(C x)E(C x). Then G is a Chevalley group over an algebraically closedﬁeld of characteristic =2.A minimal group is a group ofﬁnite Morley rank whose proper deﬁnable subgroups are soluble-by-ﬁnite.Fact2.10(Cherlin and Jaligot[14])The Pr¨u fer2-rank of a minimal sim-ple tame group ofﬁnite Morley rank and of odd type is≤2.3PreparationIn this section G will always stand for a group ofﬁnite Morley rank.If H is a group,H#=H\{1}is the set of nontrivial elements of H,I(H) denotes the set of involutions of H andΩ(H)stands for the subgroup generated by I(H).We will use the notationΩ(H)only when the elements of I(H)will commute with each other so that in our case we will haveΩ(H)=I(H)∪{1} and I(H)=Ω(G)#.Lemma3.1An involution of a K-group of odd type with nonsoluble connected component commutes with an inﬁnite2-subgroup.5Proof:Let G be the group in question.We claim that it is enough to prove the statement for G=G/O(G).Let i∈I(G)and let us assume that we know the result for G and the involution i of G.Let T be a nontrivial Sylow◦2-subgroupof CG (i).Let B be the full lifting of CG(i)to G,i.e.B={g∈G|g∈CG(i)}.Clearly B is a deﬁnable subgroup of G containing O(G)and i.For b∈B,sinceb∈CG (i),the subgroups i b and i are Sylow2-subgroups of O(G) i .Thusthere is an a∈O(G)such that i b=i a.Hence b=(ba−1)a∈C G(i)O(G).Thismeans that B=C G(i)O(G).Since T is abelian,its deﬁnable closure d(T)is abelian as well[10,Corollary5.38].Thus the lifting of d(T)to B=C G(i)O(G)is soluble(Fact2.4).Nowwe can apply Fact2.3:T=S=SO(G)/O(G)for some Sylow◦2-subgroup Sof C G(i)O(G),which is necessarily nontrivial.Since the Sylow◦2-subgroup ofC G(i)is also a Sylow◦2-subgroup of C G(i)O(G),conjugating by an elementof O(G)we may assume that S≤C G(i).Thus i commutes with a nontrivialabelian divisible2-subgroup of G.Hence we can assume that O(G◦)=1(Fact2.4).Let i∈I(G).By Fact2.6,G◦is the central product ofﬁnitely many quasi-simple algebraic groups and ofan abelian group F:=F(G)◦ G,say G◦=G1∗···∗G n∗F.Let L=G1∗···∗G n. Since i normalises L and L=1,we can assume that G=L i .If i swapstwo of the quasi-simple components G j and G k,then ss i|s∈S ,where S is a Sylow2-subgroup of G j,is an inﬁnite2-subgroup of C G(i)and we are done. Therefore we may assume that i normalises each component.This allows us to be able to assume that L is just one component,i.e.G=L i and L is quasi-simple algebraic.Now it is time to invoke the following fact.Fact3.2(Theorem8.4of[10])Let G H be a group ofﬁnite Morley rankwhere G and H are deﬁnable,G an inﬁnite simple algebraic group over an alge-braically closedﬁeld and C H(G)=1.Then,viewing H as a subgroup of Aut(G),we have H≤Inn(G)Γwhere Inn(G)is the group of inner automorphisms of GandΓis the group of graph automorphisms of G.By Fact3.2,we have two cases:i acts on L either as an inner automorphismor as an inner automorphism composed with a graph automorphism.In bothcases the lemma easily follows from the description of centralisers of involutionsin semisimple algebraic groups[15]. Lemma3.3Let G be a K-group of odd type with nonsoluble G◦and pr2(G)≥3.Let S be a Sylow2-subgroup of G.Then not all the involutions of S◦are G-conjugate.Notice that the assumption pr2(G)≥3cannot be weakened:if K is analgebraically closedﬁeld of characteristic distinct from2then the group G=PSL3(K)has2-Pr¨u fer rank2and only one class of conjugate involutions. Proof:Assume otherwise.Since we do not introduce new involutions by re-placing G by G/O(G)(Fact2.1),we may assume that O(G)=1.6By Fact2.6,G◦is a central product ofﬁnitely many quasi-simple algebraicgroups and of an abelian group F,say G◦=G1∗···∗G n∗F.Let L=G1∗···∗G n. Since G1has an involution and L G,all the involutions of G are in L.Case1.Z(L)has an involution.Then all the involutions of G◦are in Z(L).Thus each G i is a quasi-simple algebraic group whose involutions are in Z(G i).From the classiﬁcation of simple algebraic groups(e.g.[19]),it follows that G i SL2(K i)for some algebraically closed K i of characteristic=2.Thus L is a central quotient of SL2(K1)×···×SL2(K n).It is easy to see that SL2(K i) is2-divisible,thus any nontrivial central quotient of SL2(K1)×···×SL2(K n) will introduce noncentral involutions.Therefore G◦=SL2(K1)×···×SL2(K n). Since pr2(G)≥3,n≥ 3.Now,G permutes the components G1,...,G n. Therefore G leaves invariant the set{i1,...,i n}where i j∈I(G j),so that i1 and i1i2are not conjugate,a contradiction.Case2.Z(L)has no involutions.Then we can assume without loss of generality that Z(L)=1and that each G i is a simple algebraic group over an algebraically closedﬁeld of characteristic=2.Let S be a Sylow2-subgroup of L.Then A:=Ω(S◦) (A∩G1)×···×(A∩G1)(no more amalgamation). By Fact2.2,N G(S◦)acts transitively on the involutions of A.But N G(S◦) permutes the components also.Thus if a1∈A#∩G1and a2∈A#∩G2, then a1and a1a2cannot be conjugate.Hence n=1.Thus G acts transitively on the involutions of the simple algebraic group G1.Fact3.2tells us how G acts on G1.Now the result follows from the classiﬁcation of the conjugacy classes of involutions in simple algebraic groups and their extensions by graph automorphisms[15]. Lemma3.4Let G be a group of odd type.Let S be a Sylow2-subgroup of G.Let¯denote“modulo”O(G).Then S,2=ΓS,2(G).Proof:Since S is a Sylow2-subgroup of G by Fact2.3,clearly the left hand side is a subgroup of the right hand side.To prove the reverse inclusion,it is enough to show that if B≤S is a four subgroup then there is a lifting A of Bto G such that A is a four-subgroup of S and NG (B)≤GLet B≤S be a four-subgroup.Let X be the full preimage of B in G.Since X/O(G)=B≤S=SO(G)/O(G),we have X≤SO(G).Let A be a Sylow 2-subgroup of X.By Fact2.3,X=O(G)A and A B.Since A≤X≤SO(G) and since S is a Sylow2-subgroup of SO(G),conjugating by an element of O(G),we may assume that A≤S.We will show that NG(B)≤N G(A).Letx∈NG (B).Then A x=B x=B=AO(G)/O(G),and A x≤AO(G).ThusA x is a Sylow2-subgroup of AO(G).Therefore there is a y∈O(G)such that A x=A y.Thus x=(xy−1)y∈N G(A)O(G)and x∈G This proves the lemma. Lemma3.5Let G be a simple K*-group of odd type,S a Sylow2-subgroup of G and H=ΓS,2(G),the2-generated core associated with S.Let A be an elementary abelian2-subgroup of H with m(A)≥3.If a∈A#then C a≤H.7Proof:Let B=C G(a).Let A1be a four-subgroup of A disjoint from a .Consider the K-group B A1of odd type.By Fact2.8,B◦= C◦B (x)|x∈A#1 .But C◦B(x)≤C G(a,x)and a,x is a four-subgroup of S.Thus B◦≤H. 4Proof of Theorem1Let G be a group as in the statement of Theorem1.Let S be aﬁxed Sylow 2-subgroup of G,A=Ω(S◦) S and H=ΓS,2(G)be the2-generated core attached to S.Clearly S≤N G(S)≤N G(S◦)≤N G(A)≤H because A char S and A has order at least8.We assume H<G.Claim1.If a∈A#then C G(a)≤H.Proof:Let B=C G(a).By Lemma3.5,B◦≤H.Now let b∈B be any element.Then S◦b is a Sylow◦2-subgroup of B◦.Hence S◦b=S◦c for some c∈B◦.It follows that b=(bc−1)c∈N G(S◦)B◦⊆H.Thus B≤H. Claim2.If a∈Ω(T)#for some Sylow◦2-subgroup T of H,then C G(a)≤H. Proof:Conjugating by an element of H,we may assume that a∈A.Now the claim follows from Claim1. Claim3.If i∈I(S),then C i≤H.Proof:By looking at the Jordan normal form of i as a linear transformation of the F2-vector space A(of dimension at least3),we see that i must centralise at least a four-subgroup of A.Let A1be a four-subgroup of A that is centralised by i and set B=C i.The four-group A1acts on B.Applying Lemma2.8tothe K-group B A1of odd type we get B= C◦B (c)|c∈A#1 .Hence B≤Hby Claim1. Claim4.If i∈I(H),then C i≤H.Proof:Conjugating by an element of H,we may assume that i∈I(S)so that the claim follows at once from Claim3. Claim5.H◦is soluble.Proof:Assume,to the contrary,that H◦is nonsoluble.This will allow us to prove that any two elements of A#are G-conjugate.Indeed,let a,b∈A#.Assume a and b are not G-conjugate.We use the following fact:Fact4.1([11],Proposition10.2of[10])Any two involutions of a group of ﬁnite Morley rank are either conjugate to each other or commute with another involution.Therefore,for every g∈G,b g and a commute with some involution i(that may depend on g).By Claim1,i∈C G(a)≤H.By Claim4,C i≤H.Since H is a nonsoluble K-group of odd type,we can apply Lemma3.1:C H(i)contains a nontrivial Sylow◦2-subgroup T.Since b g∈C H(i),we can choose T so that b g normalises T.But then b g centralises some involution t∈T and b g∈C G(t)≤H8by Claim2.Thus b G⊆H.But this contradicts the fact that G is simple and that H<G and proves that all involutions in A#are G-conjugate.Our next observation is that N G(S◦)≤N G(A)≤H and N G(S◦)controls H-fusion in S◦by Fact2.2.Hence all involutions in S◦are conjugate in H, which contradicts Lemma3.3.Now,in view of Claim5,Theorem1follows from the following result.(We state and prove a slightly more general result than we need for the present paper,since it will be used in subsequent papers.)Proposition4.2Let G be a simple K*-group of odd type with a soluble and proper2-generated core.If n(S)≥3for a Sylow2-subgroup S of G,then G is a minimal group.Proof:Assume that G is not minimal.Then G has a proper deﬁnable non-soluble connected subgroup,say K.Take K minimal with this properties.By Fact2.6,if K=K/O(K),then K=F(K)E(K)and F(K)is an abelian group. Since L(K)=1,by the minimality of K,K must be isomorphic to either SL2(F) or PSL2(F)for some algebraically closedﬁeld F of characteristic=2.Clearly the2-generated core of K is a subgroup of a2-generated core of G.Therefore the2-generated core of K is also soluble.By Lemma3.4,the 2-generated core of K is also soluble.The further analysis of the structure of G requires a structural result about groups PSL2(K).Lemma4.3The connected component of a2-generated core of PSL2(K)where K is an algebraically closedﬁeld of characteristic distinct from2is non-soluble.1 Proof:Let T be the standard maximal torus of G=PSL2(K)(that consists of diagonal elements).Let S be a Sylow2-subgroup of G=PSL2(K)such that S◦≤T.Then S=S◦ w for some w∈I(N G(T)\T).Since w inverts T, S is generated by its involutions.Let z be the unique involution of Z(S)≤S◦. Every involution t=z of S belongs to the four-subgroup z,t .Also z∈ z,w . Thus S≤ΓS,2(G).Set H=ΓS,2(G).Assume that H is soluble.Notice that N G( z,t )is a subgroup of H and is isomorphic to the symmetric group Sym(4)(which is naturally interpreted as the group of permutations of4points in general position on the projective line).Therefore there is an element r∈H such that z r=t.But then S◦and S◦r are two Sylow2-subgroups of H◦and contain commuting involutions z and t,correspondingly.But H◦is solvable and so is contained in a Borel subgroup of G.The latter is conjugate to the group of upper triangular matrices in G and contains no commuting involutions.We now return to the proof of Proposition4.2.By Lemma4.3,K PSL2(F).So K SL2(F).But then K has a central involution¯z in the connected component of a Sylow2-subgroup.Lifting its centraliser to K,we 1Notice that it follows from Poizat[18]that H◦=G,although we do not need the full strength of this result.9see that we have an involution z in a Sylow◦2-subgroup S◦of G with nonsol-uble C z.Let A be a normal elementary abelian subgroup of S with m(A)≥3.Notice that[S◦,A]≤S∩A is aﬁnite group.Since S◦is a divisible abeliangroup,it is easy to see that[S◦,A]is also divisible.This shows that[S◦,A]=1andΩ(S◦)A S is a normal elementary abelian subgroup of S of2-rank at least3.By Lemma3.5applied toΩ(S◦)A,C z≤H◦and therefore H is nonsoluble. This is a contradiction and completes the proof of Proposition4.2,as well asthe proof of Theorem1. 5Proof of Theorems2and3As usual,G stands for a simple K*-group ofﬁnite Morley rank and odd type.The proof of Theorems2,5.4and3is based on the concept of a signaliserfunctor,which we now deﬁne.Assume that,for every involution s∈G,we have a connected deﬁnable2⊥-subgroupθ(s)≤C G(s)such that(i)θ(t)∩C G(s)=θ(s)∩C G(t)for any commuting involutions t,s∈G,and (ii)θ(s)g=θ(s g)for any g∈G(in particular,θ(s) C G(s)).Thenθis called a signaliser functor on G.The signaliser functorθis complete if for any elementary abelian2-subgroupE≤G of order at least8the subgroupθ(E):= θ(t)|t∈E#is a connected2⊥-group andCθ(E)(s)=θ(s)for any involution s∈E.Finally,a signaliser functorθis nontrivial ifθ(s)=1for some involution s∈G,and nilpotent if all the subgroupsθ(t)are nilpotent. Fact5.1Let S be a Sylow2-subgroup of G.Assume n(S)≥3.Let E S be an elementary abelian normal2-subgroup of S of2-rank at least3.Ifθis a nontrivial complete signaliser functor on G thenθ(E)=1andΓS,2(G)≤N G(θ(E)).In particular,if G is simple then it has a proper2-generated core.Proof:The deﬁnition of signaliser functor given above is stronger than that of[8](where only the weaker conditionθ(s) C G(s)was required in(ii)).Thisﬁllsa gap in the proof of[8,Theorem6.7]which gives the desired result.(Noticethat in[8],Theorem6.7was applied only to signaliser functors which satisﬁedthe stronger assumption(ii).) We need one more technical result.For an elementary abelian2-subgroup V,we setΓV= C v|v∈V# .10Proposition5.2Let G be a simple K*-group of odd type and of Pr¨u fer2-rank at least3.Let S be a2-Sylow subgroup of G and E=Ω(S◦).ThenΓS,2(G)≤N G(ΓE).Proof:We introduce the graph∆whose vertices are all the elementary abelian 2-subgroups of G of order at least4,with two vertices(subgroups)U and V connected by an edge if[U,V]=1.The group G acts on∆by conjugation.It follows from[8,Lemma4.5]that if U and V are elementary abelian subgroups in S of order at least4then they belong to the same connected component∆0 of∆.We need the following lemma.Lemma5.3If U and V are commuting elementary abelian2-subgroups of or-der at least4in G thenΓV=ΓU.Proof:Take an involution v∈V,then C G(v)is a proper subgroup in G and thus is a K-group.By Fact2.8,C v= C◦C(u)|u∈U# ≤ΓU,vand thusΓV≤ΓU.By symmetry,ΓV=ΓU.Returning to the proof of Proposition5.2,we observe thatΓV=ΓU for any two vertices U and V in∆0;denote this subgroup by M.Then,for any elementary2-subgroup V<S of order at least4,N G(V)normalisesΓV=M and M=ΓE,henceΓS,2(G)≤N G(ΓE),as claimed.We are now in a position to prove Theorems2and3.It will be convenient toﬁrst prove the following intermediate result. Proposition5.4Let G be a simple K∗-group of odd type.Then either G is a Chevalley group over an algebraically closedﬁeld of characteristic=2,or one of the following holds:(a)pr2(G)≤2;(b)O(C G(z))=1for some involution z∈G,or(c)G is a minimal group.Let us start with Proposition 5.4.Excluding clauses(a)and(b),we can assume that G has Pr¨u fer2-rank at least3and that O(C G(x))=1for any involution x∈G.In particular(Fact2.6),for every element x∈I(S),C x=F(C x)E(C x),which gives us condition(2)of Fact2.9.If the condition(1)of Fact2.9does not hold,then Proposition5.2says that G has a proper 2-generated core.But then,by Theorem1,G is a minimal group,which yields the clause(c)of Proposition5.4.Therefore we can assume that the assumptions11of Fact2.9hold and thus G is a Chevalley group over an algebraically closed ﬁeld of characteristic=2.In Theorem2we assume that G is tame.Under this extra assumption, we need to exclude clause(b)from Proposition5.4.The following result comes handy:Fact5.5(Corollary6.8of[8])If in a tame K*-group G of Pr¨u fer rank at least3,O(C G(t))=1for some involution t∈G,then G has a proper2-generated core.But then G is a minimal group by Theorem1.Now a result of Cherlin and Jaligot on minimal tame groups(Fact2.10)bounds the Pr¨u fer2-rank of G. This proves Theorem2.The folowing recent result of JeﬀBurdges[12]on signaliser functors is in-volved in the proof of Theorem3:Fact5.6(Burdges[12])Let G be a simple K*-group of odd type.Assume that O(C G(t))=1for some involution t∈G.Then G admits a nontrivial nilpotent signaliser functor.If now G is simple K*-group of odd type and of Pr¨u fer2-rank at least3 with O(C G(t))=1for some involution t∈G,then G has a nontrivial nilpotent signaliser functor.But a nilpotent signaliser functor is complete[7,12].Now Fact5.1forces G to have a proper2-generated core,implying that G is minimal by Theorem1.This proves Theorem3.AcknowledgementsThe authors thank JeﬀBurdges for making his unpublished work[12]available, Ay¸s e Berkman for stimulating discussions and Gregory Cherlin and Eric Jaligot for pointing out to a few inaccuracies in an earlier version of the paper. 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直升机海上搜救最优模式研究

2001年3月系统工程理论与实践第3期　文章编号:100026788(2001)0320087205直升机海上搜救最优模式研究张福光(烟台海军航空工程学院,山东烟台264001)摘要:　在给出直升机海上搜救概念的基础上,应用人机工程学理论和运筹学原理建立遇险目标及直升机的运动模型和观察人员发现概率模型,经仿真计算,利用比选法得出了直升机海上搜救的最优模式Λ关键词:　海上搜救;视野;生存概率中图分类号:　U676.83 文献标识码:　A αStudy of the Op ti m al Search andR escue M odel of H elicop ter on SeaZHAN G Fu2guang(N aval A eronau tical Engineering A cadem y,Yan tai264001,Ch ina)Abstract　F irst w e give the concep t of the search rescue mode of helicop ter on sea andthen the k inetic models of the target in danger and the helicop ter and the ob servers’spo tting p robab ility model are bu ilt by app lying the hum an engineering theo ry and theoperati on s research p rinci p les.U sing the m ethod of comparison and selecti on,theop ti m al search&rescue model of helicop ter on sea is ob tained based on the si m u lati onresu lts.Keywords　search and rescue on sea;view ch s field;su rvival p robab ility1　引言海上搜救,是指对已知或未知的海上目标(海上失事的舰船或人员)组织搜索与救援的实施过程,目的是救援失事的目标Λ搜索过程是搜救过程中的主要部分,其效率是影响搜救效果的主要因素Λ随着我国经济与军事的发展,海事活动日益增多,对海上搜索、救援的快速要求也越来越高Λ直升机海上搜救具有快速机动、覆盖面广、搜索效率高、救援效果好等特点,因而开展此方面的研究具有重大的现实意义Λ在岸台或舰艇遇险系统接收到遇险目标发出的求效信号并判明方位后,海难救助部门通知直升机基地或离出事地点较近并载有直升机的舰船进行搜救Λ在条件允许时,直升机应立即起飞,以预定的飞行速度、飞行高度抵达遇险区域后,在区域内按预定方式进行搜索,直至发现目标或直升机由于油量限制必须返回为止Λ救护舰船则向遇险区域以最大巡航速度作直线航行,以接应返航的直升机或搭救直升机无法救援的目标Λ当直升机发现目标后,在立即向舰船指挥员报告的同时应对目标进行救援Λ2　仿真模型的建立211　搜救目标运动模型21111　目标初始分布区域α岸台的定位精度直接影响到搜索时的效率Λ目前,我国沿海广泛采用的罗兰2C定位系统能够自动搜索、跟踪和连续测定方位,并显示目标的经纬度,系统的导航定位距离大于900海里,导航定位绝对精度范围为0.4海里-1.2海里Λ21112　目标运动速度搜救目标落水时,其距离海岸一般有较大的距离(相对于乘座无动力救生器材的目标更是如此)Λ在此情况下,目标一般不可能尽全力以最大速度向某个方向运动Λ因此,我们假定目标在初始分布区域中的某点以适当速度向某个他(或他们)认为正确的方向运动,其运动方向一经确定即不再改变Λ目标的运动速度v h由洋流运动速v p与目标自身运动速度v m合成得到Ζ设二者之间的夹角(v m逆时针旋转至v p)为Α1,则v h的幅值v h=v2p+v2m-2v p v m co s(Π-Α1)0ΦΑ<Πv2p+v2m-2v p v m co s(Α1-Π)ΠΦΑ1<2Π 运动方向(v h逆时针旋转到v p)ΑΑ=arcco sv2h+v2p-v2m2v h v m0ΦΑ1<Π2Π-arcco sv2h+v2p-v2m2v h v mΠΦΑ1<2Π21113　水平运动坐标系取罗兰2定位系统测定的目标初始分布圆域的中心点为水平坐标系的原点o,洋流运动方向为ox轴的正方向,oy轴垂于x轴并指向直升机载舰Ζ212　直升机运动模型对于直升机而言,较大的搜索力意味着在目标分布区域的最大航程,所以直升机在飞往目标初始分布区域及飞回载舰平台(机场)的过程中,均应使用正常巡航速度和相应高度,在起飞时载油量取允许量最大值Ζ为保证直升机安全,返回载舰平台(机场)时必须留有一定比例的油量Ζ直升机在抵达目标分布区域后,即可按照下列搜索模式搜索目标:1)随机搜索模式:直升机在目标分布区域内随机运动,观察人员目力搜索目标Ζ2)平行搜索模式:由于目标分布区域为一个不断平移扩展的圆域,在进行环形搜索时,直升机环绕开始搜索瞬间位移后的中心点并由里至外进行搜扫,直至目标所在圆域的边缘,再由外至里进行搜扫Ζ3)螺线搜索模式:直升机按目标运动中每个方向上的可能“点”进行搜索,如果目标不在某一预定的“点”上,则搜索者驶往另一可能的“点”进行搜索Ζ213　目力搜索模型21311　视区根据人体的视觉机能,我们确定直升机上观察人员的视区如图1所示Ζ图1　直升机观察人员视区其中:G点为直升机所处位置;A、E点为观察人员视区左右两侧的后缘;B、D点为观察人员视区左右两侧的前缘;O点为直升机在海平面坐标系中的投影;F、C点为点O与视区后缘连线A E及前缘边线B D的垂直相交点Ζ观察人员分辨搜救目标的最大距离为L:L=Q2tgΥ(3)式中:Υ表示观察人员分辨搜救目标的最小视角,视觉机能良好时Υ=11.5′,Q表示搜救目标垂直于视线方向的长度Ζ,其垂直平面内的自然视线低于水平38°,对海洋(蓝色)的水平视野为左右各40°,垂直视野为上下各20°,即如图1所88系统工程理论与实践2001年3月示梯形区域A B D EΖ每次瞥视区域A B D EΖ每次瞥视的区域为水平左右各2°,垂直自然视线上下各20°,如图1所示的阴影区域Ζ21312　目力搜索发现目标的概率当对某个视区的瞥视次数为n次时,观察人员发现目标的概率为P n=1-(1-g)n式中:g表示视野内的目标瞥视的发现率,g=1-2-(C r C t)Β　Β为常数,一般取2;(5) 1)C r表示目标反差,C r=C0×e-Ρv・R・k;(6)　C0为目标固有的反差,一般取C0=0.75;Ρv为平均衰减系数,亦称空气透明系数;R为观察者与目标之间的距离;k为统计结果(期望值为0,方差Ρ=3.912 R v,R v为能见距离);2)C t为阀值反衬度,C t和f之间的关系为lg(C t+2)×(lg f+0.5)=1f=S R×360×60(7) S为目标的视向截面积如图1所示,S=hG M =h[(x m-x z)2+(y m-y z)2+h2]1 2S1其中:h为直升机的搜索高度;S1为目标的面积;x m,y m为目标在水平坐标系中的坐标;x z,y z为直升机在水平坐标系中的坐标Ζ3)视力对直升机搜索高度的限制直升的搜索高度受到其动升限及观察人员视力的限制,在图1所示视区A B D E中,点D(或B)距离G 点的距离最远,即GD段的长度不允许大于直升机上的观察人员的最大可视距离(GDΦL).经推导,处于D点面积为S1的目标的视向截面积S=S1 4.22GD=4.22hΦL=Q2tg13′,故有　hΦQ8.44tg13′(8)在这里必须注意:a搜救目标的面积或直径Q超过单个目标的数值时,直升机搜救的限制高度可以增大,使搜扫效率提高Ζ但是搜救人员出发时可能并不清楚搜救目标的面积和大小,所以限制的飞行高度只能以单个目标为基础计算;b上述限制高度是在假定空气的透明系数为1的情况下求得的,所以在实际运算中,还必须考虑透明系数Ρv对飞行高度的影响,即h限ΦΡv hΖ4)视力对直升机搜扫速度的限制为保证直升机上的观察人员能够将搜扫宽度内的任一点观察一次,而观察如图1所示A B D E区域的最短时间应为观察人员的中心视线从左至右(或从右至左)均匀扫视一次,在扫视区域A B D E的时间内直升机的运动距离应不大于FC的直线距离Ζ由于每次瞥视的水平视野只是在中心视线左右2°(共4°)的范围内,所以,观察整个视区(80°)所需的时间:T=水平视野范围(80°)单次瞥视范围(4°)×瞥视频率Χ=20Χ(9) 在时间T内直升机的直线运动距离应不大于如图1所示的FC的长度,即v xΦFCT=h(tg72°-tg32°)Χ 20=0.1226Χh(10) 5)搜索宽度Ξ由图1,搜索宽度Ξ可取视区横向宽度的后缘边A E长度,即98第3期直升机海上搜救最优模式研究Ξ=2h tg40°(11)3　海上搜救的度量指标救援落水人员的度量指标应为成功概率,对于浸泡在海水中的人员而言,在其生存时间之后再得到救援意义很小Ζ因此,海上搜救的度量只能是在一定的时间范围内搜救成功的概率Ζ落水人员的生存时间是指人体在正常状态下,身体浸泡在海水中能够存活的最长时间,其主要取决于个体抵抗寒冷的能力以及海水的表层温度Ζ前提是人员在落水时没有发生溺水以及在漂流的过程中没有被海洋动物损伤等意外情况Ζ海水落水人员冻僵是指海上落水人员在低温海水浸泡下出现的肌僵病理状态,是影响海上落水人员生存时间的主要因素Ζ据统计,正常的人体浸泡在0℃水温的海水中时,最长存活12分钟;水温为10℃时,最长存活2小时40分钟;水温为20℃时,最长存活16小时20分钟Ζ根据以上参考数据,在不考虑溺水、海洋动物损伤等意外情况的基础上,我们拟合出落水人员在海水中的生存时间为:tt =0.54exp (0.172T C )-0.34(12)式中:tt 为落水人员在海水中的生存时间(小时);T C 为海水温度(℃)Ζ4　仿真结果及分析411　仿真结果利用上述仿真模型,针对某型舰载直升机的海上搜救进行正交仿真试验和灵敏度仿真试验,仿真结果如图2-图7所示:图2　三种搜索方式下的生存概率图3　环境对生存概率的影响图4　人员运动速度对生存概率的影响图5　定位精度及目标距离对生存概率的影响09系统工程理论与实践2001年3月图6　直升机搜索高度对对生存概率的影响图7　直升机搜索速度对生存概率注:图3-图7直升机采用均匀搜索方式412　结果分析1)均匀搜索优于其它搜索方式Ζ2)影响落水人员生存概率的客观因素有:环境条件(包括能见度和海水的表层温度)、遇险地点与载舰之间的距离、定位系统的定位精度和直升机的综合性能Ζ3)增大落水人员的生存概率的方法有:①加强对搜救人员的训练,提高搜救人员素质;②海上遇险人员如果确信求救信号已被岸台接收到,或自救的概率较小(如离岸较远)时,应尽量降低自身的运动速度以提高自身的生存概率;③在允许范围内,直升机采用最大高度搜索;④直升机采用最大允许速度的63.1%-73.7%搜索Λ4)直升机飞机海上搜救最优模式①在冬春两季,落水人员在海水中生存时间较短,舰载直升机可以不必达到覆盖要求(覆盖目标分布区域至少一次)而立即放飞;在夏秋两秒,为避免浪费直升机的搜索力,必须达到覆盖要求才能放飞;②直升机飞往目标分布区域中心点以及返回的过程中,采用最大巡航速度及对应的高度;③直升机到达通报的目标分布区域中心点后,应采取均匀搜索方式;④目力观察时,直升机应采用限制的最大高度、65%左右的允许最大速度飞行;⑤当直升机发现目标后,在立即向舰船指挥报告的同时对目标进行救援Λ参考文献:[1]　张最良等1军事运筹学[M ]1北京:军事科学出版社,19931[2]　张序三等1海军大词典[M ]1上海:上海词书出版社,1993119第3期直升机海上搜救最优模式研究。

impact on the gut immune system and

Probiotics,prebiotics,and synbiotics: impact on the gut immune system andallergic reactionsPascal Gourbeyre,Sandra Denery,and Marie Bodinier1INRA,UR1268,Unite´de recherche sur les Biopolyme`res,leurs Interactions et Assemblages,Nantes,France RECEIVED NOVEMBER23,2009;REVISED DECEMBER3,2010;ACCEPTED DECEMBER10,2010.DOI:10.1189/jlb.1109753ABSTRACTProbiotics and prebiotics,alone or together(synbiot-ics),can inﬂuence the intestinal microbiota and modu-late the immune response.They may therefore be tools that can prevent or alleviate certain pathologies involv-ing the gut immune system,such as allergies for which no treatment is yet available.This review focusesﬁrst on the deﬁnitions of probiotics,prebiotics,and synbiot-ics and key cells in the gut immune system.It then dis-cusses their effects on mucosal immune stimulation. Experimentalﬁndings suggest that different probiotic species have similar effects on innate immunity by im-proving the mechanisms of pathogen destruction.On the contrary,their impacts seem to be variable on the adaptive immune system.Prebiotics can also exert an inﬂuence on the gut immune system via the stimulation of the autochthonous bacteria metabolism.Finally,this review focuses on the effects of food supplements on allergy.Different studies performed in humans or ro-dents have supported a potential role for selected pro-biotics and prebiotics in reducing some allergic param-eters.Probiotic effects on allergy treatment are un-clear,especially in human studies.However,they are potentially effective at short-term for prevention when they are administered in perinatal conditions.A clinical study performed with an infant cohort revealed a bene-ﬁcial effect of prebiotics in preventing allergic manifes-tations at long-term.Further studies are nonetheless essential to conﬁrm theseﬁndings.Food supplements offer potential tools for the prevention or treatment of allergy,but insufﬁcient evidence is available at present to recommend their use in clinical practice.J.Leukoc. Biol.89:685–695;2011.IntroductionIn1998,probiotics were described as:“live microorganisms which,when consumed in adequate amounts,confer a health beneﬁt on the host”[1].Prebiotics have been deﬁned as“non-digestible food ingredients that beneﬁcially affect the host by se-lectively stimulating the growth and/or the activity of one or a lim-ited number of bacterial species already resident in the colon,and thus attempt to improve host health”[2,3].A synbiotic is deﬁned as a product that contains both prebiotic(s)and probiotic(s).These food supplements have numerous and complex effects on the intestinal microbiota and gut immune system.Their properties mean that they may have some interesting applications in some pathological situations involving the gut immune system[4–6]. However,at present,there is no evidence(or only some prelimi-nary evidence)of their potential therapeutic application in the prevention or treatment of gut pathologies such as inﬂammatory bowel diseases[7]or allergies[8,9].Epidemiological studies have indicated that the prevalence of allergic disorders,such as allergic rhinitis,asthma,and eczema,has risen during recent de-cades in many Western countries[10,11].This increased disease incidence seems to be associated with a variety of environmental factors:the hygiene hypothesis,antibiotic use,increased chemical exposure,lifestyle changes,or a Western-style diet low inﬁber and antioxidants[12–14].As yet,there is no treatment that can cure allergies,thus enhancing the interest of using functional foods enriched in prebiotics or probiotics.This review provides an overview of data about probiotics,prebiotics,and synbiotics and discusses the varying deﬁnitions of them suggested by differ-ent investigators.Key cells of the gut immune system are de-scribed,and the effects of these food supplements on mucosal immune stimulation,and ultimately,allergic diseases are consid-ered.Our aim has been to determine whether there are sufﬁ-cient,valid arguments to support the use of these food supple-ments in the prevention and treatment of allergic diseases. DEFINITIONS OF PROBIOTICS, PREBIOTICS,AND SYNBIOTICSProbioticsProbiotics are microorganisms(bacteria,yeast)that exert a beneﬁcial effect on host health[15].When some of these mi-1.Correspondence:INRA,UR1268,Unite´de recherche sur les Biopoly-me`res,leurs Interactions et Assemblages(BIA),F-44316Nantes,France.E-mail:bodinier@nantes.inra.frAbbreviations:ADϭatopic dermatitis,DTHϭdelayed-type hypersensitivity,FOSϭfructooligosaccharides,GOSϭgalactooligosaccharides,LGGϭLactobacillus rhamnosus GG,NODϭnucleotide-binding oligomeriza-tion domain,PPϭPeyer's patches,PRRϭpattern recognition receptors,SCFAϭshort-chain fatty acid,SOSϭsoybean oligosaccharides,TregϭTregulatory cellReview 0741-5400/11/0089-685©Society for Leukocyte Biology Volume89,May2011Journal of Leukocyte Biology685croorganisms are ingested,they are able to resist the physico-chemical conditions prevailing in the digestive tract[16],and the strains most frequently used as probiotics belong to the genera Biﬁdobacterium and Lactobacillus[17,18].Allochthonous lactobacilli and biﬁdobacteria(probiotics)ingested as food or supplements need to be differentiated from the autochtonous organisms that constitute human commensal microbiota.The populations of these bacterial genera,whatever their origin (allochthonous or autochtonous),differ between individuals and can be affected by environmental factors such as drugs and diet.Probiotics can act on the gut immune system(as dis-cussed later).They also play non-immune,protective roles by directly blocking intestinal pathogenic microbes and enhanc-ing mucosal integrity via epithelial cell stimulation.Directly blocking intestinal pathogenic microbesProbiotics can directly inhibit the growth of pathogens by pro-ducing antibacterial substances,including bacteriocins(such as lantibiotics)and different acids(acetic,lactic,and propi-onic acid)[19,20].They can also decrease the adhesion of pathogens and their toxins to the gastrointestinal tract through their ability to adhere to intestinal epithelial cells.In vitro studies have demonstrated that probiotics possess lectin-like adhesion components able to bind on carbohydrates from glycoconjugate receptors of the epithelial cell surface[21–23], thus blocking pathogen binding to intestinal epithelial cells. Moreover,some probiotic strains belonging to the Lactobacillus genus have displayed in vitro abilities to bind to the surface of enterocytes[24].Enhancing mucosal integrityFirst,probiotic bacteria can enhance the integrity of the intes-tinal barrier.Indeed,Ewaschuck et al.[25]established thatBiﬁdobacterium infantis increases resistance in an in vitro model of the intestinal barrier(T84human epithelial cells),and other probiotics,such as Lactobacillus plantarum,act on tight junctions by increasing the expression of zonula occludens pro-teins and occludins[26].Probiotics are also able to induce the production of cytoprotective substances by enterocytes,such as the heat shock proteins[27]and antimicrobial peptides,e.g., defensin[28]and mucin[29,30],to prevent bacterial adher-ence.Finally,they may be involved in preventing cytokine-in-duced epithelial damage by promoting the survival of intesti-nal epithelial cells by activating antiapoptotic and inhibiting proapoptotic pathways[31].In summary,probiotics are able to exert an impact on the intestinal environment through different key non-immune mechanisms.PrebioticsA variety of molecules can be prebiotics,but the great majority is dietaryﬁbers,such as oligosaccharides.Their principal ef-fect is related to the metabolism of the microbiota.Indeed,if no dietaryﬁber is present in the colon,anaerobic bacteria draw their energy from protein fermentation.This metabolism leads to the production of toxic and potentially carcinogenic compounds(such as ammoniac or phenolic compounds)[32, 33].By contrast,the fermentation of carbohydrate(such as dietaryﬁber)generates SCFAs,such as acetate,propionate,or butyrate[34],which are not toxic to the host[32],and consti-tutes potential fuel for epithelial cells.For instance,in an in vivo rat model,a fructan(inulin,FOS)-enriched diet has in-creased the production of SCFA[35].The interesting proper-ties of SCFAs on the intestinal barrier and gut immune system are discussed below.Several oligosaccharides are considered to be prebiotics,such as inulin,GOS,FOS,SOS,and xylooligo-saccharides.The most widely studied have been inulin,GOS, FOS,and a mixture of GOS and inulin[36,37].These mole-cules are resistant to in vitro digestion by pancreatic and brush-border enzymes[38].Chicory is the principal industrial source of inulin,from which FOS are often obtained by partial enzymatic hydrolysis[39].GOS are produced from lactose us-ing␤-galactosidase[40].Each bacterial genus or species has a preferential substrate.Most strains belonging to the Biﬁdobacte-rium and Lactobacillus genera preferentially use fructans rather than glucose as a substrate[41,42].However,other bacteria such as Clostridia and Bacteroides are also able to grow on fructans[35,43].Nevertheless,their growth is less efﬁcient than that of Biﬁdobacterium because of less-efﬁcient substrate absorption(notably on oligofructose)[43].Thus,prebiotics actﬁrst to ensure selective stimulation of the activity of beneﬁ-cial autochtonous bacterial strains[38],but they do not stimu-late the same genera of intestinal microbiota in humans and rodents.Indeed,in humans,prebiotics speciﬁcally increasebiﬁdobacterial populations in fecal samples[33,44,45], whereas lactobacilli populations are increased signiﬁcantly in the fecal microbiota of rodents(rat,mouse)[46,47].Last but not least,some prebiotics(GOS)can exert a direct antimicro-bial effect,as they can adhere to the binding sites of bacteria on the enterocyte surface and thus,block the adhesion of pathogenic bacteria to intestinal epithelial cells[42,48].In conclusion,although it is clear that prebiotics have some effects on microbiota(modiﬁcation,stimulation,antipatho-genic effect),little is known about the speciﬁc action of each type of oligosaccharide on the various genera and species that make up the microbiota.SynbioticsA combination of probiotic(s)and prebiotic(s)constitutes a synbiotic[2,16],which can stimulate and increase the survival of probiotic and autochthonous-speciﬁc strains in the intesti-nal tract.Su et al.[49]administered some combinations to mice,each containing one prebiotic(FOS,SOS,or inulin) and one probiotic(Lactobacillus acidophilus,Biﬁdobacterium lac-tis,or Lactobacillus casei).They then analyzed the amounts and survival of each probiotic strain in fecal samples.A SOS-or FOS-containing diet appeared to stimulate the growth of L. acidophilus and sustain its highest level.FOS and inulin dietary treatment exerted the same effects on ctis.SOS,FOS,or inulin improved the survival and retention time of L.casei. Such effects have also been demonstrated in humans,as the administration of probiotic LGG with GOS was seen to signiﬁ-cantly increase the amount of allochtonous Lactobacillus rham-nosus and autochthonous biﬁdobacteria and lactobacilli in fe-ces from treated children[50].Human breast milk contains oligosaccharides(more diverse and more complex than those found in many animal milks) [51]and lactic acid bacteria,which may be potentialprobiot-686Journal of Leukocyte Biology Volume89,ics[52,53].Breast milk can therefore be considered as a syn-biotic food.It has been evidenced that bacteria from human milk can colonize the gut of a breast-fed child[53].Some studies have also suggested that oligosaccharides from breast milk may inﬂuence the establishment of autochtonous micro-biota in breast-fed children[17].Indeed,differences in terms of microbiota composition have been observed between breast-fed and formula-fed children.In particular,it has been estab-lished that the Biﬁdobacterium genus is more common in the feces of breast-fed infants[17,51].KEY CELLS OF THE GUT IMMUNE SYSTEM AND THEIR INTERACTIONSWITH MICROORGANISMSCells for antigen absorptionThe induction sites of the immune response in the gut corre-spond to follicles of GALT organized at the level of PP.M cells present in PP play a key role because of their ability to transport macromolecules,microorganisms,and inert particles from the lumen into lymphoid tissue through adsorptive endo-cytosis.The uptake of antigens,macromolecules,and microor-ganisms can also occur through active transepithelial vesicular transport in enterocytes[54]and M cells[55].Finally,DCs may extend their dendrites through epithelial tight junctions and thus,capture luminal antigens directly[56].When anti-genic molecules have been transported across the intestinal barrier,they can then stimulate the innate and adaptive im-mune systems.Cells of innate immunityThese cells act as theﬁrst line of defense against pathogens but are not overly speciﬁc in their ability to recognize their targets.Key players in the innate immune response include phagocytic cells,such as neutrophils,monocytes,macrophages, and NK cells.Cells of adaptive immunityDCs,macrophages,and monocytes provide an interface be-tween the innate and adaptive immune systems,as they act as professional APCs.This“bridging”role is crucial to initiating the adaptive immune response,as T cells do not respond to free antigens but only to those presented by APCs.In adaptive immunity,distinct subsets of CD4ϩTh cells(Th1,Th2,orTh17)are described on the basis of their cytokine secretion proﬁles after the activation and differentiation of naive CD4ϩcells[57](see Fig.2).IL-12IL-12enables the differentiation of naive T cells into Th1lym-phocytes,which are involved in the tolerance and defense mecha-nisms of the host against pathogens via the production of differ-ent inﬂammatory cytokines such as IL-2and IFN-␥[58].IL-4IL-4enables the differentiation of naive T cells into Th2lym-phocytes.Th2cells produce cytokines(IL-4,IL-5)that can ac-tivate B lymphocytes so that they produce IgE.They are impli-cated in the mechanisms of parasite defense,atopy,and aller-gic reaction[59].TGF-␤,IL-6,and IL-1TGF-␤,IL-6,and IL-1are involved in the generation of Th17 cells.These cells secrete IL-17and IL-22,which are critical to regulating tissue inﬂammation[60].Th17cells have been shown to protect against extracellular bacteria and fungal in-fections,as well as contributing to some autoimmune re-sponses[61].Naı¨ve CD4ϩT cells are also converted into potent immuno-suppressive cells,CD4ϩCD25ϩTregs,by TGF-␤[62].Tregs, through their IL-10and TGF-␤production,are able to check the immune response,block Th1(autoimmune diseases)or Th2(al-lergic diseases)hyperpolarization,and thus,regulate the Th1/ Th2balance.The recognition of microorganisms and their role in immune response inductionDCs recognize different pathogens via microbial PRRs and translate these signals into factors that polarize Th1and Th2 cells[61,63].TLRs,which discriminate between different types of pathogens,are the most common PRRs(Fig.1).The binding of TLR4or TLR9to bacterial ligands,such as un-methylated CpG and LPS,turns immature DCs into IL-12-pro-ducing and Th1-promoting DCs[64,65].The PRR known to mediate the differentiation of Tregs and Th17cells appears to be TLR2,which is able to recognize lipoteichoic acid on Gramϩbacteria[65,66].The PRRs that mediate Th2-promot-ing DCs still need to be determined.NOD proteins are homol-ogous to TLR,as they contain leucine-rich repeats and recog-nize pathogenic components at the cell surface.NOD2is ex-pressed by intestinal epithelial cells,canﬁx LPS and peptidoglycans,and activates LPS-mediated pathways such as NF-␬B[67].Consequently,NOD2serves as a key component in the innate mucosal response to luminalbacteria.Figure1.Mechanisms underlying the differentiation of naive CD4؉T cells into CD4؉T cell subsets.Th1,Th2,and Th17cells and Tregs.Inﬂuence of cytokine production by DCs and the triggering of TLR by pathogenic molecules.Gourbeyre et e of food supplements for the prevention or treatment of allergy Volume89,May2011Journal of Leukocyte Biology687TLR and NOD proteins can be activated by speciﬁc probi-otic strains.Indeed,Tobita et al.[68]established that heat-treated Lactobacillus crispatus KT strains could induce TLR2and NOD2activation in C3H/HeN mouse PP.Numerous actors in the gut immune system have now been presented.So what are the effects of food supplements,such as probiotics or prebiotics,on these immune actors?EFFECTS OF PROBIOTICS ANDPREBIOTICS ON THE GUT IMMUNE SYSTEMImmunomodulatory properties of probioticsProbiotic antigenic fragments (e.g.,cell wall compounds)are able to cross the intestinal barrier via intestinal epithelial cells [69]and M cells [70]at the level of PP.They are then pro-cessed and presented to the immune system and modulate the innate and adaptive response (Fig.2).Modulation of innate immunityProbiotics are endowed with antiviral properties,in that they increase the cytotoxic potential of NK cells and phagocytosis capacity of macrophages [71].Indeed,cell wall components,such as the lipoteichoic acid of Gram ϩbacteria (biﬁdobacteria or lactobacilli),can stimulate NO synthase [72]and induce the production of NO (a virus-infected cell death mechanism)by macrophages (via TNF-␣secretion).This mechanism in-volves an up-regulation of important surface phagocytosis re-ceptors such as Fc ␥RIII [73]and TLR [74].Modulation of the adaptive immune responseMany probiotic strains seem to be capable of stimulating the production of IgAs by B cells,which bind antigens andthereby,limit their access to the epithelium [71].In children with viral gastroenteritis caused by rotavirus,probiotics such as LGG have been shown to stimulate rotavirus-speciﬁc IgA anti-body responses,which are theoretically signiﬁcant in the pre-vention of reinfections.They can thus reduce the number and duration of episodes of diarrhea [75].Probiotics interact with a wide variety of cells (enterocytes,DC,Th1,Th2,Treg)in the intestine and may modulate the immune response toward a pro-or anti-inﬂammatory action.This appears to be a strongly strain-dependent effect.First,it has been shown in in vitro cell models (enterocyte models,such as HT-29,caco-2,and DC derived from PBMC)that probiotics can inﬂuence the production of cytokines by intestinal APC and,initiate the orientation of the adaptive re-sponse.Indeed,it has been demonstrated that Lactobacillus sakei induces the expression of IL-1␤,IL-8,and TNF-␣(proin-ﬂammatory),whereas Lactobacillus johnsonii stimulates the pro-duction of TGF-␤(anti-inﬂammatory)in Caco-2cells [76].Second,it has been observed in animal models that probi-otic strains can modulate the Th1/Th2balance toward Th1activation (proinﬂammatory effect)or Th1inhibition (anti-inﬂammatory effect).Using a food allergy model to study the Th2response in mice,Shida et al.[77]showed that an i.p.injection of heat-killed L.casei Shirota induced a rise in serum IL-12levels and a skewing of the cytokine proﬁle from Th2to Th1(proinﬂammatory effect).Vidal et al.[78]reported that supplementation with Lactobacillus paracasei also enhanced Th1cell-dependent immune responses in a mouse model.How-ever,recent studies have supported the potential anti-inﬂam-matory effect of Lactobacillus strains in rat colitis [79,80].Pro-biotics may also favor the production of an anti-inﬂammatory cytokine,IL-10.This is a cytokine that acts primarily to inhibit the inﬂammatory response,produced by many cell types (Th2cells,DCs,monocytes,B cells,and Tregs)[81].This immuno-modulatory effect has also been assessed in human clinical studies (see Effect of probiotics on allergy).Indeed,the con-sumption of LGG was shown to increase IL-10production in the serum of children with AD [82].Finally,it has been shown that two probiotic species belong-ing to the same genus may have antagonist effects on each other.For example,L.casei subsp.alactus alone has been char-acterized during in vitro culture cell experiments as an in-ducer of proinﬂammatory cytokines in DCs.However,this ef-fect was not observed with a mixture of L.casei subsp.alactus and Lactobacillus reuteri [83].This antagonistic effect of a pro-biotic mix has also been observed in animal models.The ad-ministration of L.casei ,Lactobacillus delbrueckii subsp.bulgaricus ,and L.acidophilus in mice increased the systemic production of IgG1,typical of a Th2response,but L.acidophilus alone en-hanced the production of IgG2a,typical of a Th1response [84].In conclusion,if different probiotic species have equivalent effects on innate immunity by improving mechanisms ofpathogen destruction,their effects appear variable (sometimes antagonist)on the adaptive immune system as a function of strains.Immunomodulatory properties of prebioticsPrebiotics can exert an effect on the intestinal barrier and gut immune system that is mediated by the SCFAs produced by microbiota.One of these SCFAs,butyrate,has been the most studied.Butyrate has been identiﬁed as a modulator ofhistoneFigure 2.Prebiotic and probiotic effects on the innate and adaptive immune responses.A nonspeciﬁc antiviral effect through the stimula-tion of innate immune cells:increase in the cytotoxic activity of NK cells and macrophage phagocytosis.As a function of the probiotic strains,pro (Th1cells)-or anti (Th2cells and Tregs)-inﬂammatory responses of the adaptive immune system can beactivated.688Journal of Leukocyte BiologyVolume 89,May 2011tail acetylation,and consequently,it can increase the accessi-bility of many genes to transcriptional factors(activator or re-pressor)[85].The transcriptional effects of butyrate on differ-ent subsets of cells involved in the gut immune system have been studied in vitro:neutrophils[86],enterocytes(up-regula-tion of NOD2expression in Caco-2cells)[87],and DCs(im-pact on DC maturation)[88].It was thus observed in entero-cyte models that butyrate enhanced the intestinal barrier by regulating the assembly of tight junction proteins[89].All of these studies were performed in vitro on cultured cell lines, but the transcriptional effect of butyrate has also been demon-strated in vivo in humans.Vanhoutvin et al.[90]established that the local administration of butyrate resulted in an in-creased transcription of the genes mainly associated with en-ergy metabolism and inﬂammation(TNF-␣signaling).Bu-tyrate is produced by the Clostridium,Eubacterium,and Rumino-coccus genera,whereas other SCFAs,such as acetate or propionate,are produced by lactic acid bacteria of the Biﬁdo-bacterium and Lactobacillus genera.As mentioned above,prebi-otics stimulate the activity of lactic acid bacteria much more than butyrate-producing bacteria.So butyrate alone cannot explain the effects of prebiotics on the gut immune system; propionate and acetate must also play key roles in the regula-tion of expression of immune system genes.Indeed,Cavaglieri et al.[91]showed that lymphocytes harvested from LNs and cultured with acetate,propionate,and butyrate produced high levels of IL-10,whereas butyrate alone had little effect.Kiefer et al.[92]demonstrated that propionate signiﬁcantly modu-lates histone acetylation in HT-29cells.EFFECTS OF PROBIOTICS,PREBIOTICS, AND SYNBIOTICS ON ALLERGYThe intestinal epithelium is constantly exposed to a multitude of foreign materials that can be harmful or beneﬁcial to the organism.Consequently,the intestinal immune system needs toﬁnd a balance between the protective immune responses that are induced following an encounter with intestinal patho-gens or toxins and the tolerance of commensal bacteria and food antigens.Inadequate protective immune reactions can cause severe immune disease and are actively prevented in healthy individuals.Food antigens and commensal bacteria constitute the majority of the antigen load in the intestine, and the“default”reaction of the immune system confronted with them leads to systemic unresponsiveness.This phenome-non is known as oral tolerance and is a key feature of intesti-nal immunity[93].The result of interactions among intestinal contents,unique anatomical features,and immune and non-immune cells is an environment that favors the tolerance by the induction of IgA antibodies(by TGF-␤-secreting Th3cells) and CD4ϩTregs(producing IL-10and IFN-␥).This ensures that a homeostatic balance is maintained between the intesti-nal immune system and its antigen load,so that it retains the ability to recognize dangerous and harmless antigens as for-eign and preserves the integrity of the intestinal mucosa.The inappropriate immune responses to food and commensal bac-teria that are responsible for celiac disease,Crohn’s disease, and food allergy are a result of a deregulation of these crucial processes[94,95].Inϳ6%of children and4%of adults in the United States,tolerance of a given dietary antigen is not established or breaks down,resulting in food hypersensitivity. Although food allergies can result in sudden and life-threaten-ing symptoms,their prevalence is remarkably low considering the complexities of the gut-associated mucosal system[96].An allergic reaction mainly corresponds to the activation of Th2 cells against food allergens and occurs in two phases(Fig.3): theﬁrst phase corresponds to transport of the allergen through the intestinal barrier,its capture by APCs(DC or en-terocyte),and its presentation to naive Th0cells,which differ-entiate in the presence of IL-4into Th2cells.Activated Th2 cells then produce an IL-4cytokine that enables the produc-tion of allergen-speciﬁc IgE by B cells[97].These secreted IgEs then bind to mast cells via the IgE receptor Fc␧RI.The activation phase corresponds to the degranulation of mast cells after further exposure to the same allergen that links directly with speciﬁc IgE on the surface of these cells.This phenome-non triggers release of the allergic mediators involved in clini-cal manifestations of allergy.The gut microbiota plays a cru-cial role in the establishment of tolerance to food antigens. Indeed,studies about axenic mice revealed a failure in the acquisition of tolerance to some food proteins[98].Differ-ences in terms of microbiota genus and species have been ob-served between allergic versus healthy individuals in some studies.Indeed,He et al.[99]have found major differences in the fecalﬂora of these two populations in terms of the proﬁles of biﬁdobacteria species and their ability to adhere to human intestinal mucus(more adherent in healthy children).By monitoring the gutﬂora of allergic and healthy children from two different countries(Estonia and Sweden),Bjo¨rkste´n et al. [100]evidenced a lower colonization by anaerobic bacteria (biﬁdobacteria)and elevated counts of some aerobic species (coliforms)in children developing an allergic tendency at the age of2years.Thus,modiﬁcations to gut microbiota in aller-gic individuals through the use of food supplements such as probiotics or prebiotics could in the future constitute aninter-Figure3.Description of the sensitization and activation phases of the allergic reaction.Prebiotic and probiotic effects on the Th1/Th2bal-ance;an impact on allergy?Gourbeyre et e of food supplements for the prevention or treatment of allergy Volume89,May2011Journal of Leukocyte Biology689esting strategy to prevent or treat allergic diseases.Indeed,at present,the standard of care for food allergy includes a strict avoidance of food allergens and ready access to self-injectable epinephrine.The problems involved in avoiding food aller-gens and the potential for sudden and life-threatening reac-tions can diminish the health-related quality of life of patients and their families.Effect of probiotics on allergyNumerous animal and human studies have been performed to test the potential effects of different probiotic strains,mainly in the context of preventing and treating allergies. Probiotics as tools for allergy preventionAnimal models Most studies have been performed in animals with distinct genetic backgrounds:different mouse strains[68, 101–105],rats[106],and dogs[107].In most cases,the probi-otic effects were assessed in adults(mice aged6–8weeks). Fewer studies have focused on the inﬂuence of perinatal ad-ministration(given to the mother or pups).The effectiveness of some probiotic strains in preventing allergy has been shown in many studies by an increase in the Th1response(Escherichia coli Nissle[101],Lactococcus[102],several biﬁdobacteria and lactobacilli[103]);an alleviation of clinical symptoms(Lactoba-cillus[104]);and an increase in TLR2expression(Lactobacillus [68]).However,negative effects of probiotics on allergy have also been evidenced[105,106].Indeed,de Jonge et al.[106] showed that L.casei Shirota administered to3-to4-week-old Brown Norway rats before allergen sensitization increased the Th2response and the number of basophilic granulocytes in the blood.Yang et al.[105]observed that live Biﬁdobaterium adolescentis and Biﬁdobaterium longum administered to Balb/c mice increased DTH and spleen lymphocyte proliferation.It therefore appears that not all probiotic strains have the same effect on preventing allergy:only some of them are effective and can achieve prevention,and others stimulate the allergic response.We consider that these heterogeneous effects of probiotics can also be explained by the diversity of study methods,in terms of the differences in parameters,such as the genetic background of animals,their age,the probiotic strains used, the state of bacteria(live or heat-killed),or the sensitization mode.Human studies Human studies can be considered sepa-rately as a function of the perinatal conditions of probiotic administration.The probiotics were given only to the children (ﬁve studies)[108–112]or to mothers and children(ﬁve stud-ies)[113–117].Under theﬁrst condition of administration (children only),it is impossible to reach a clear conclusion as to the effect of the probiotic,as all of the potential impacts on allergy were observed:an increase in allergy[112],no effect [109–111],or a clear decrease[108].Of theﬁve studies using a combined approach(mothers and children),the majority appeared to suggest a protective effect on allergy[113,115, 116]with a reduction in the incidence of atopic eczema.How-ever,the analysis of the cohort developed by Kallioma¨cki et al. [113]in the longer term(2–4years[118]and7years[119]) showed that the probiotic effect was not sustained over the long-term.Moreover,the study of Kopp et al.[117],which had been developed with the same experimental protocol as Kallioma¨cki et al.[113],did not demonstrate any effect of the strain at short-term.The same percentage of children devel-oped an allergy,and there was no difference in IgE concentra-tions.They also observed that children with recurrent episodes of wheezing bronchitis were more frequently in the probiotic group.Various strains of probiotics have been used during studies in humans and animals,but that most studied has been LGG [110,113,117].Surprisingly,although administered under the same conditions,this strain seems to have contradictory ef-fects.Thus,of the two studies about LGG administration in mothers and children[117,118],only one[118]established a slightly positive effect of LGG on allergy prevention at6 month of age(reduced risk of atopy).Moreover,when LGG was administered in children only,Scalabrin et al.[110]saw no preventive effect.Consequently,even if the combined approach(motherϩchildren)has enabled more positive results in the short-term than other modes of administration,insufﬁcient data are available to afﬁrm that probiotics can prevent allergy in humans.In conclusion,the heterogeneity in the design of animal and human studies(different strains,doses,periods of expo-sure,and environmental conditions)could explain the contra-dictory effects of probiotics on preventing allergy.However, individual parameters are also likely to be responsible for these disparities,such as the environment,the composition of microbiota,or genetic background,etc.Thus,probiotics can-not yet be considered to constitute effective tools to prevent allergy.Probiotics as tools for the treatment of allergyAnimal models Only three studies[120–122]have been car-ried out using animal models.They involved the use of mice of various ages(3–8weeks)and different probiotic species alone or combined by intranasal or oral ways after allergen sensitization[Lactococcus lactis,L.casei,Biﬁdobacterium breve,B. infantis,Biﬁdobacterium animalis,L.plantarum,L.rhamnosus). These studies evidenced a reduction in the allergic response, characterized by a decreased Th2response(reduced produc-tion of speciﬁc IgG1,IgE,and IL-4)and an increased Th1re-sponse(augmentation of TNF-␣and IFN-␥production). Despite their disparities in terms of protocol design,the re-sults of these studies were consistent with a beneﬁcial thera-peutic effect of probiotics.Nevertheless,further studies are necessary to conﬁrm the interesting effects of this food supple-ment and to explain the mechanisms involved.Human studies Human studies about probiotics as a treat-ment for allergy have revealed varying impacts:a beneﬁcial effect of probiotics causing a decrease in Severity Scoring of Atopic Dermatitis Index levels in patients who received probi-otic-supplemented formulas[123–126],a moderate effect [127–129],or no effect[130].L.rhamnosus sp and particularly, LGG are still the most widely studied probiotics[124,125, 127–130].The effectiveness of this latter probiotic strain on the treatment of AD has not yet been assessed.Indeed,only two studies have described a clear improvement in allergic symptoms[124,125].Finally,in a setting of AD,Brouwer etal. 690Journal of Leukocyte Biology Volume89,。

虎小奇翻译(1)

ISSN 1007-0214 17 / 19 pp105 112LIU Xinjun (刘辛军) , WANG Jinsong (汪劲松) , LI Tiemin (李铁民) * * , DUAN Guanghong (段广洪)并行机制有两个或三个自由度wi th a closed -loop kinema tic st ructure t o co nt rol i n 1955 ( Fig. 1a ) where t he m ov ing element w as mani pulato r as an ai rcraf t sim ulat or i n 1965 IntroductionMechanical systems that allow a rigid body t omove with respect to a fix ed base play a very important role in numerous applications. A rigid body can move in various translational or rotational directions which a re called degrees of freedom( Do Fs ) . The total number of degrees of freedomf o r a rigid body cannot exceed six , f or example, three-translation motions along mutuallyorthogonal axes and three-rotational motions about these ax es. A robot includes a system to controlseveral degrees of freedom of an end-effect or. The last few years have witnessed import antdevelopment s i n the use of industrial robots, m ai nly due to their flexibility. How ever, theMechanicalarchitecture of the most comm on robot s is not w ell adapt ed t o cer tai n tasks. Other types of a rchi tectures hav e, t heref ore, recent ly beendev elo ped fo r i ndust ria l use, including parallel m anipulat ors. A pa ral lel m anipulat o r, which is a closed-loo p m echa nism , t ypically co nsists of a m ov ing plat fo rm t ha t is connected to a fi xed base byReceiv ed: 2001-10-11; r evised: 2002-05-28* Suppo rted by the N ational  973 Pr og ram o f China( No. G1998030607)* * To who m co rrespondence should be addr essed.E-mail: litm@ pim. tsinghua. edu. cn;several limbs o r legs. Typically , the number of limbs i s equal to t he number of degrees of freedom such that every limb is controlled by one act ua to r and all the actuators can be mounted a t o r near the fix ed base. For this reason, parallel mani pulat ors are so metim es called plat fo rm mani pulato rs. Because the ex t ernal load can be sha red by the actua to rs, pa rallel manipula to rs tend to hav e a larg e load-carrying capacit y. Pa rall el mani pulat ors are alw ays presented as havi ng v ery go od perf orma nce i n t erms o f accuracy, rigidi t y a nd the abilit y to manipula te large loads. They hav e been used in a la rg e number o f applica tions ranging f rom astro nom y to fligh t si mulato rs , and are becomi ng i ncrea si ng ly po pular in the machine-too l industry.T he conceptual desig n o f parallel mani pulat ors can be dat ed back t o 1947, when Go ugh est ablished the basic pri nci ples of a m echani sm [1 ] the posi tio n a nd orientati on of a moving pla tf orm t o test ti re wear a nd damag e. He bui lt a pro to ty pe [2 ] a hexag onal plat fo rm w hose v ertices w ere all co nnect ed to links by ball-and-socket joi nts. The ot her end of the link was at t ached to the base by a univ ersal joi nt. Six li near actuat ors modi fied the t ot al li nk leng th . Stewa rt desi gned a pla tf orm [3 ] ( Fig. 1b ) , in w hich t he moving el em ent w as a Tel: 86-10-62773375t ri ang ula r pla tf orm w hose v ertices were all106 Tsinghua Science and Technology , February 2003, 8( 1): 105 112connected by ball-and-socket joint s t o support m echa nism s each co nstit uting of t wo jacks, also pa rall el ma ni pulat ors, wi th the planar th ree-RPS pa rall el mani pulato r as a t ypical ex ampl e. Si nceplaced in a t ri ang le. In 1978, Hunt [4 ] made a then, pa ral lel m anipula to rs hav e been st udied systema tic st udy o f the kinematic st ructure of ex tensiv el y by numero us researchers.act uat ors .ki nematic linkag es, as Huntand Lerbet already fo rmula i s nev ertheless generally used, whichi= 1M ost o f the six -Do Fs pa rallel manipula to rs st udi ed t o dat e hav e i ncluded si x ex t endi ble lim bs. T hese parallel mani pulato rs possess the adv antag es o f high stif f ness, lo w i nertia , and larg e paylo ad capaci ty. Ho w ev er , they suff er the problems of rela tiv ely small usef ul w orkspace and desig n di fficulties. Furt herm ore, their di rect ki nema ti cs i snum ber o f deg rees of f reedom of t he end-ef fecto r. ∉ T he mobi li t y o f the m anipulat or i s zero whenthe act uat ors are locked. Parallel mechanisms a re o f interest f or the fo llow ing reasons: ∉ T he load can be di st ri but ed on the multiple li nkag es. v ery dif ficul t to a naly ze. Theref o re, parallel m anipulat ors wi th l ess than si x Do Fs have ∉ Few actua to rs a re needed. ∉ When t he act ua to rs a re locked , the increasingly a tt racted at tentio n fo r i ndust ry mani pulato r remai ns i n posi ti on, w hich i s an applicatio ns. This paper int roduces pa rall el m anipula to rs and the classificatio n o f parallel ma ni pulat ors. Th ree ty pes of new pa rall el mani pulato rs are int roduced: a spatial th ree-Do Fs pa rall el mani pulato r, a t w o- Do Fs parallel ma ni pulat or, and a plana r t hree- Do Fs serial-parallel m anipulat or. 1 Definition of a Parallel ManipulatorA pa rall el mani pula to r is made of an end -ef f ecto r w it h n deg rees of freedom w ith a fix ed base li nked tog ether by a t least t w o i ndependent ki nematic li nkag es. Act uatio n takes place t hroug h n -sim ple [ 5] These mechanisms hav e t he fo llow ingcha ract eristics: i mport ant safet y co ncern fo r cer tai n appli cati ons. Parallel manipula to rs f or w hi ch t he number of li nkag es is st rictly equal t o t he num ber of deg rees of f reedom of the end-ef fecto r a re cal led fully pa rall el mani pulato rs. 2 Degrees of Freedom of a Mechanism The deg rees of f reedom of a m echa nism are the num ber o f i ndependent pa ram eters or i nputs needed to completely specif y the config ura ti on of the mechanism. Ho w ev er, a g eneral m obili ty cri teri on ca nnot be easily defi ned fo r closed-lo op [4 ] [ 6]no t ed. Classical m obili ty fo rmulae can i ndeed neg lect som e deg rees o f f reedom. Grubler 's [7 ] ∉ At least tw o linkag es support the end-ef fecto r. Each o f tho se li nkag es co ntai ns a t least o ne si mple act ua to r. may be w ri t ten as M = d ( n - g - 1) + g f i ( 1) ∉ The number of act uat ors is t he sam e as the w here M is system mobi li t y ( degrees of f reedo m) ;LIU Xinj un (刘辛军) et al: Parallel Mechanisms with Two or Three Degrees of F reedom d is screw system o rder ( d = 3 f or pla nar andspheri cal moti on, d = 6 f or spatial mo tio n) ; n i snumber o f links including t he f rame; g is num bero f joint s; and f i are deg rees o f f reedo m associat edw it h t he i -t h joint.3 Classification of ParallelManipulatorsT he to tal num ber of deg rees o f f reedom o f a rigidbody ca nnot exceed 6; theref ore, the number of 107Do Fs o f a parallel ma nipulat or wil l be betw een 2 and 6. Si nce the fi rst parallel m echa nism desig n ,m any mechanical desig ns have been pro posed fo r parallel mani pulato rs w it h 2 t o 6 Do Fs. A surv eyo f 87 act ua to rs pro posed in the li terature show ed that 40% has si x Do Fs, 3. 5% fiv e Do Fs, 6% f our Do Fs, 40% th ree Do Fs, and the remaini ng t w o[7 ]3. 1 Two-DoFs parall el manipul atorsMost existing tw o-Do Fs parallel m anipulat ors are plana r mani pulato rs wi th tw o-transla ti onal Do Fs. Such desig ns use only pri sma tic a nd revo lute joi nt s. M cClo y [8 ] sho wed that there are 20di ff erent com bina tio ns. Thi s number is reduced t o 6 as show n i n Fig . 2 if the actuato rs a re assumedto be at tached to the g ro und. There is no passive prism atic joi nt and no actuato r i s supporti ng thew ei ght of a no ther actuato r.Fig. 2 Six types of two-DoFs parallel manipulators3. 2 Three-DoFs parallel manipulatorsThere are many three-Do Fs parallel mani pulato rs, so o nl y the classical desi gns wi ll be presented here. One exam ple i s the planar t hree-RRR ( R standsfo r rev olving joint ) parallel mani pulato r as show n i n Fig . 3a. T he movi ng pla tf orm has three plana r Do Fs , which are tw o t ransla tions alo ng the x a nd y ax es and o ne rot atio n around the ax is perpendicula r t o the O -x y plane. Ano ther ex ample i s t he spherical th ree-RRR pa ral lel m anipulat or as show n in Fig. 3b , i n w hi ch all the joint axesi ntersect a t a com mon ver tex. The mo tio n o f a ny poi nt i n the m echa nism is ro ta tion about thev ertex. The mov ing platf orm has only ro tational[4]th ree-RPS pa rall el m anipulat o r show n in Fig. 3c,Do Fs .Do Fs wi th res pect to the base. Hunt present ed the108 Tsinghua Science and Technology , February 2003, 8( 1): 105 112w hi ch has co mplex Do Fs, which ca nno t be st rict ly defined. The most famo us robot wi th th ree[9 ][9 ]Com pany and ABB under t he name IRB 340 3. 4 Five-DoFs parall el manipulatorsFive-Do Fs f ul ly parallel ma nipulat ors m ust hav e F = 29 /5, so there are no five-Do Fs f ully pa ra llel mani pulato rs. A fiv e-Do Fs parallel manipula to rFpex Picker. DEL T A has been wi dely used i n propo sed by Austad [11 ] consists of tw o pa ra llel industry. Ano ther ty pe of three-Do Fs parallel mani pulato rs.m anipulat or has the movi ng plat fo rm co nnect ed t o the base th ro ugh fo ur leg s, w here the fo urth leg i s passiv e and i s also the leadi ng leg , which means that the l eg determines the mo tion o f the m ov ing plat fo rm, f or ex ample, i n the spherical coo rdina te parallel ma ni pulat or show n i n Fi g. 3e. T hi s parallel manipula to r is used f or the machine to ol[10 ]3. 3 Four-DoFs parallel manipulatorsA fo ur-Do Fs fully parallel mani pulato r has d = 6, n= 10, g = 12, a nd M = 4. Substit uting these coeffi cients i nto Eq. ( 1) g ets F= 22 /4, which i s the deg rees o f f reedom f or each leg. T heref ore, there a re, act ually , no f our-Do Fs fully parallel m anipulat ors. The early m echani sm s wi th f our- Do Fs w ere no t f ul ly parallel mani pulato rs, i. e. , m anipulat ors wi th tw o act ua to rs per linkag e o r 3. 5 Six-DoFs parallel manipulatorsSix -Do Fs parallel mani pulato rs are the mostpo pular mani pulato rs so they hav e been st udied ex tensiv el y. The archi t ecture show n i n Fig . 4a is a classical six -Do Fs parallel mani pulato r. M ost si x- Do Fs parallel ma ni pulat ors hav e si x ex t endible li mbs. T hese parallel manipula to rs po ssess the adva nt ag es o f hi gh stif f ness, low inertia, and la rg e pay load capaci ty. How ev er, they suf f er the problem s of relativ ely small usef ul w o rkspace a nd desig n dif ficulti es. Furthermo re, ana lysis of thei r direct ki nematics i s v ery dif ficul t. There a re also so me exo tic chai n manipula to rs i n w hi ch the mani pulato r is actuat ed by a planar mechanism, such as a fo ur-bar mechani sm , o r a fiv e-ba r mechanism, o r w hi ch hav e tw o actuato rs per leg and w hi ch usually hav e t hree leg s.t ransla ti ons i s the DEL T A ( Fig. 3d) , pro posedby Clav el and ma rket ed by the Demaurexdesi gn by IFW of th e Univ ersit y o f Hannover .propo sed by Pierro t has each pai r o f legs i n the 4 Evolution of Parallel ManipulatorsAf t er Goug h established t he basic princi pl es ofm echa nism s wi th closed -loop ki nema ti c structures in 1947, as sho w n i n Fig. 1a, m any o ther parallel m anipulat ors wi th a specified number and ty pe of deg rees of f reedom have also been proposed. The a rchi tecture desi gned by Stew art i n 1965 i s show n in Fi g. 1b. As show n i n Fig. 4a , theo retical ly v ery co mpact st ruct ure t ha t ca n be used i n microsy stem [12 ] . The ar ra ngement o f t he six leg s show n i n Fig. 4c makes the manipula to r mov e f reely along a speci fied direction, which is very useful fo r th e i ndust rial applicati ons. A six -Do Fs parallel m anipulat or simila r t o that [13 ] mani pulato r show n in Fig . 4a parallel t o each ot her. The number of Do Fs of the manipula to r will be dif ferent i f the input s to the tw o legs i n each speaki ng , the six leg s can be arrang ed at w ill t o pair are the same. The equiv alent manipula to r desi gn v arious si x-Do Fs pa rall el ma nipulat ors, archit ect ure is show n in Fig. 5. T he manipula to r such a s the ma ni pulat or sho w n in Fig. 4b , where out put w ill be t hree t ranslatio ns, which is the l eg s are a rra ng ed i n a 3-2-1 sty le w hi ch i s a probably the o rigi n o f the DEL T A robo t. TheLIU Xinj un (刘辛军 ) et al: Parallel Mechanisms with Two or Three Degrees of F reedom 109 act uat ed li nks can be ar ranged as t he w el l-know n, f ast robot DEL T A sho w n i n Fig. 3d. DEL T A ha s been made in sev era l versio ns, such as the Polla rdLeg s ( 1) and ( 12) hav e i dentical chai ns wi th a co nsta nt link connected to a univ ersal joi nt ( o r tw o rev olut e joint s) ( 15) o r ( 13) a t the bot to m end a nd m echa nism . T sai 's ma ni pulat or [15 ] , Fig . 3f , i s a passiv e revo lute joi nt ( 3) or ( 11) a t th e ot her also among th ree t ra nsla tional parallel end. Th e revo lute joint i s then a t tached to an m anipulat ors. Alt houg h Tsai 's mani pulat or ha s activ e slider ( 4) or ( 10) , w hich is mo unt ed o n the t ransla ti ons identical w it h tha t o f DEL T A, i t i s no t exact ly a versio n o f DEL T A. T heir desig n concepts are diff erent and Tsai 's manipula to r is the fi rst desig n to deal wi th the problem of a U PU chain. Anot her three-t ra nsla tional Do Fs parallel gui dew ay ( 2) o r ( 9) . The t hi rd l eg ( 8) has a co nsta nt link , a pla nar fo ur-bar pa rallelog ram, w hich is co nnect ed t o a rev o lute joi nt ( 16) a t the bo t to m end a nd a passive rev olut e joint ( 5) at the ot her end. The rev olut e joint is a t tached t o an m anipulat or , St ar, was desi gn by Herv o n the g roup theo ry. [16 ] based activ e sli der ( 6) which is mounted o n the g uidew ay ( 7) . The mov em ent of the movi ng plat fo rm isThe pro posed manipula to r is a generalFig. 5 The apology architecture of DELTAAlt ho ug h these desi gn co ncept s provi de ideas t o desi gn a new manipula to r, additio nal w ork i s needed t o desi gn a ro bo t com bini ng t ra nslatio nal and ro ta tional Do Fs wi th less than six Do Fs. Fo r ex ampl e, t here are f ew spatial three-Do Fs parallel m anipulat ors com bini ng tw o spatial t ranslati ons and o ne ro tatio n, as wi ll be presented in the f ollo wi ng sectio n. 5 N ew Spatial Three-DoFs Parallel Manipulator 5. 1 M anipul ator structure hav e parallel ax es as sho w n i n Fig . 6a. The thi rd leg ca n prov ide one constraint o n t he ro ta ti on of the movi ng pla tf orm about t he axi s. Hence, the co mbi natio n of the three leg s co nst rai ns the ro tatio n of the movi ng pla tf orm wi th respect t o the x and z ax es and the t ranslatio n alo ng the axi s. Therefo re, the m echa nism has tw o translati onal deg rees i n the O -yz plane a nd o ne ro tati onal deg ree of f reedom abo ut the y axi s. 5. 3 Novelties and applications The m echa nical desig n is i nt eresti ng because o f the thi rd act uati ng l eg m echa ni sm w hi ch uses a plana r fo ur-bar parallelog ra m, as used in o ther pa ra llel mechanisms, such a s Star Li ke robot , the Tsai T he spa tial t hree-Do Fs pa rall el manipula to r [ 17]. T hi s uni que spatial show n in Fi g. 6a consists of a base pla te, a m ov able plat fo rm, and three leg s t ha t co nnect the tw o pla tes. Each connecting leg has f our deg rees o f f reedo m. T wo o f t he t hree leg s hav e identical chains w it h a t wo -Do Fs joi nt ( or tw o 1-Do F th ree-Do Fs parallel ma nipulat or ( a ) has o nly rev olut e joi nt s, ( b) combi nes spa tial translati onaland ro tatio nal deg rees of f reedom in a spatial th ree-Do Fs parallel ma ni pulat or, and ( c) has high mo bili t y of the rot atio nal Do F. T he desig n can be joi nt s ) and t wo 1-Do F joi nt s. T he t hi rd leg practically a pplied to pa ral lel machi ne too ls. consists of a planar f our -ba r pa rallelo gram and Because o f the low m obili ty and f lexi bilit y o f si x- three 1-Do F joint s. One 1-Do F joi nt i n each leg i s act uat ed.mani pulato r, Ca PaMa nThe movi ng platf o rm is an i so sceles triang le. T he v ertices of the platf o rm a re co nnect ed to a fi xed-base plat e thro ugh l eg s ( 1) , ( 8) and ( 12) . Do Fs pa ral lel mechanisms, mo re and m ore pa ra llel machine too ls are buil t as hy brid st ruct ures , such as those o f T ri cept and Georg e V. , w hich areusua lly based on three-Do Fsparallel mecha nism s. The proposed parallel ma ni pulat or w ill be desig nedp 2R 2= ( 0 r 0) ,p 3R 2= ( - r 0 0)( 4) ref erence f ram e, cal led top f rame R 2O 2-x 2y 22, i sb 3R = ( - R 0 z 3 )( 5) p i R = Qp i R 2+ O R i i z 1 = ±】L - ( - r + y + R ) 〈+ zz 3 = ±】L - ( - rcos O + R ) - y 〈+ rsi n O + zO R = ( x y z ) TR , 110Tsinghua Science and Technology , February 2003, 8( 1): 105 112Fig. 6 New spatial three-DoFs parallel manipulatoras a hy brid pa ra llel machine t ool i n fut ure w ork.Q,T he parallel m echa ni sm can also be used as a n industrial ro bo t, a moti on simulat or, or a microm anipula to r.The desig n show n in Fig. 6a is ov er-Q =cos 0 - sin0 1 0 si n 0 co s( 3)constrai ned , which m eans that the machined where the angle is the rotation of the outputcom ponent s must be accurate. How ev er, the univ ersal joi nt s can be replaced by t w o revo lute joi nt s which a re not dif ficult to f abrica te accurat ely.5. 4 Inverse kinematics problemT he i nverse ki nematics pro bl em i nv olv es mapping a kno w n pose ( posi tio n and o ri ent atio n ) of the o utput plat fo rm to a set o f i nput joi nt va riables that wi ll achiev e that pose. A kinem atics model of the mani pulato r is show n i n Fi g. 6b. The o utput plat fo rm v ertices are deno ted as the plat fo rm joi nt s, P i ( i= 1, 2, 3) , wi th the ver tices of the base plat fo rm deno ted as b i ( i= 1, 2, 3) . A fi xed g lobal ref erence system R : O-xy z i s located a t the center o f side b 1b 2 wi th the z axis normal to the base pla teand the y axi s di rect ed alo ng b 1b 2 . Ano ther: z lo cat ed at the center of side P 1 P 2 . The z 2axi s i sperpendi cular to t he out put platf o rm and the y 2 axi s is di rect ed alo ng P 1 P 2 . T he leng th o f each legli nk i s denot ed by L , w here P i B i = L , i = 1, 2, 3. In some cases , the lengt h of link P 3 B 3 can dif f er f ro mpl at f orm with respect to the y ax is. The coordinates of point P i in the f rame R 2can be described by the v ecto r p i R 2( i= 1, 2, 3):p 1R 2= ( 0 - r 0) T ,TTVect ors b i R ( i = 1, 2, 3) wi ll be defi ned as thepo sitio n v ecto rs o f base joi nts in f rame R , b 1R = ( 0 - R z 1 ) T , b 2R = ( 0 R z 2 ) T ,TThe v ecto r p i R ( i = 1, 2, 3) i n f rame O-xy z can be w ri t ten as 2 ( 6) Then t he i nverse ki nematics of the pa ra llel mani pulato r ca n be so lv ed by the f ollo wi ngco nst rai nt equatio n, p R - b R = L , i = 1, 2, 3 ( 7) Hence, fo r a giv en mani pulato r a nd fo r prescri bedv alues of the po siti on a nd o ri ent atio n o f the pla tf orm , the requi red act ua to r inputs can bedirectly computed f ro m Eq. ( 7) , that of P 1 B 1 and P 2B 2. The objectiv e o f the i nv erse kinema tics so lutio nis to defi ne a mappi ng fro m the pose of the o utput2 2z 2 = ±】L 2 - ( r + y - R ) 2〈+ z ( 8) ( 9) plat fo rm in Cart esi an space t o the set of act uat ed input s t hat achiev e that po se. The po se of them ov ing pla tf orm is considered know n, wi th the2 2 2 ( 10) posi tio n giv en by t he po si tio n v ect o r O 2 2( 2) From Eqs. ( 8) ( 10) , we can see that t here are eig ht i nv erse ki nematic solutio ns f or a giv en poseA novel tw o-Do Fs parallel mechanism i s show nsho w n i n Fig. 8 has a m ov ing T he mechanismLIU Xinj un (刘辛军 ) et al: Parallel Mechanisms with Two or Three Degrees of F reedom 111config ura ti on sho w n i n Fig. 6, each one o f the si gns ± in Eqs. ( 8) ( 10) should be +  . 6 Other Parallel Architectures6. 1 Novel two-DoFs transl ational pl atform[19 ]in Fig . 7a. A schematic of the mechanism i s show n in Fig. 7b , w here the base is labeled 1 and them ov ing plat fo rm i s labeled 2. The movi ng plat fo rm is co nnect ed to the base by t w o identical legs. Eachl eg co nsists of a planar fo ur-bar parallelog ram: li nks 2, 3, 4, a nd 5 f o r the fi rst leg; 2, 6, 7, and8 f or the seco nd leg. T he joi nts in each pla narf our-bar parallelog ram are all rev olut e pai rs. LinksFig. 7 Novel planar two-DoFs parallel manipulator3 a nd 8 are actuat ed by prismatic act uat ors. The pla tf orm mo tio n is achiev ed by t he mov em ent s ofli nks 3 a nd 8 t ransmi t ted t o the pla tf orm by thet wo parallelog ram s. The m ov ing pla tf orm has tw opure t ranslatio nal deg rees of f reedom wit h respectt o t he base because of the planar f our-ba rpa rall elog rams. T he system is ov er-const rai ned since o nl y o ne planar f our-ba r parallelo g ram isneeded to o btain tw o Do Fs o f a rigid body in this desig n. The t wo planar f our-ba r parallelog ramsare used t o increase the system 's stif fness and to make the syst em symm etric. T his m echa ni sm isno w bei ng used to dev elop a new ty pe of fiv e-ax is machine t ool i n coo peratio n wi th the Seco nd Machi ne T ool Facto ry i n Qiqihaer, China.Fig. 8 Three-DoFs planar ser ial-parallel mechanismmani pulato rs, a spatial three-Do Fs pa ra llel6. 2 Three-DoFs pl anar serial-paral lel mechanism mani pulato r , a t wo -Do Fs parallel ma nipulat or,and a plana r t hree-Do Fs serial-pa ra llel[20 ]plat fo rm co nnected t o the base by t w o leg s. The fi rst leg consists o f a const ant li nk which i s connected t o a revo lute joint at the bo t to m end anda passiv e rev ol ut e joint at the o ther end. Therevo lute joi nt i s then a tt ached t o the base througha pri sma tic joi nt. T he second leg is v ery diff erent f rom t he f irst one wit h a va riable quadrangle o btai ned by the f lexi ng o f one side t o cha ng e the mani pulato r, are discussed. T w o of t hese desig ns are being appli ed t o new industrial machi nes. Acknowledgements T he a utho rs thank Dr. W ang Qiming and Dr. Li Jianfengfo r their discussions , and Dr. Tang X iao qia ng fo r hisco ntribution to the thr ee-Do Fs pla nar serial-pa rallelmechanism . References o ri ent atio n o f the movi ng pla tf orm. Fo ur sides of the quadrangle a re li nked to each o ther through revo lute joint s. The quadrang le i s connected to the base by a prism atic joi nt. Thi s m echa nism ha s [1 ] Go ug h V E. Co ntributio n to discussio n o f pa per s on resear ch in a uto mo bile stability , co ntro l and ty re pe rfo rmance. In: Pro c. Auto. Div. Inst. M ech. Eng . , 1956: 392 395.been used to bui ld a new t ype of fo ur-axi s m achi ne[2 ] Go ug h V E, Whitehall S G. Univ ersal ty r e test too l i n coopera tion wi th t he Jia ngdong M achi nemachine. In: Proc. 9th Inter na tional Auto mobile T ool Fact ory.7 ConclusionsT hi s paper analy zes the defi ni ti on of a parallel[3 ]Technica l Co ng ress, F. I. S. I. T. A. , Lo ndo n, 1962, 117: 117 135.Stewa rt D. A platfo rm w ith six deg rees o f fr eedo m. In: Proc. Inst. M ech. Eng. , Lo ndo n, 1965, 180: 371 386. m anipulat or and the deg rees of freedom o f a [4 ]Hunt K H. Kinema tic Geomet ry of M echanisms.112 Tsinghua Science and Technology , February 2003, 8( 1): 105 112[ 5] M e rlet J-P. Par allel Robo ts. London: Kluw er [14] Po llard W L V . Positio n contr olling appa ratus. U S Academic Publisher s, 2000. Pate nt 2286571, June 16, 1942.[ 6] Ler be t J. M echa nique des systemes de solides rigides [15] Tsai L W , Stamper R. A pa rallel manipulato r with com po rta nt des boucles ferm ees [ Disse rtation ]. Paris only t ranslational deg r ees o f fr eedo m. In: A SM E V I, Paris, June 19, 1987. ( in Chinese ) 1996 Desig n Engineering Technical Co nference, [ 7] M e rlet J-P. http: / /w ww -so p. inria. f r /co prin / Irv ine, CA, 1996, 96-DET C-M ECH-1152.equipe /mer let /merlet_ eng. html, 2001. [16] Herv J M . G roup ma thema tics and pa rallel link[ 8] M c Cloy D. Some comparisons o f seria l-driv en and mecha nisms. In: IM ACS /SICE Int. Symp. on para llel driv en ma nipulato rs. Robotica , 1990, 8: Ro bo tics, M echa tro nics, and M a nufacturing 355 362. Systems, Ko be , Ja pan, 1992: 459 464.[ 9] Clav el R. D EL T A: A fast r obot w ith para llel [17] Liu Xinjun, Wa ng J, Wa ng L P, et al. A no v elg eomet ry. In: 18th Int. Symp. o n Industria l Ro bo t, spatial thr ee deg r ees o f fr eedo m para llel manipula tor.April 1988: 91 100. In: IF AC W o rksho p o n M obile Ro bot T echno log y , [ 10 ] T onsho ff H K, Grendel H, Kaak R. Structure and Je judo Island, Kor ea, 2001: 309 314.charac teristics o f the hybrid manipula tor Geo rg e V . [18] Ceccar elli M. A new 3 D. O . F. spa tial pa rallel In: Bo er C R, M olinari-T osat ti L, Smith K S, eds. mecha nism. Mechanism and Machine Theory , 1997, Pa rallel Kinematic M achines, Spring er-V erlag 32 ( 8): 895 902.Lo ndon Limited, 1999: 365 376. [19] Liu X injun, W ang J, Wa ng L P, et a l. The co ncept[ 11 ] Austad A. A rm Device. IPN , N o. W O 87, 03239, desig n o f a nov el 5-a xis hy brid machine too l with June 4, 1987. gant ry structure. In: ISAM T '2001, N anjing , 2001: [ 12 ] Pernette E, Clav el R. Para llel ro bo ts and 493 496.mic ro ro bo tics. I SRAM '96, M o ntpellier, 1996: 535 [20] W ang J, Ta ng X, Duan G, et al. Design 542. methodolog y fo r a nov el pla na r three deg rees of [ 13 ] Pier ro t F. Ro bo ts pleinement para lleles leg er: freedom par allel machine too l. In: Pro ceeding s o f the Co nceptio n modelisatio n et commande. M ontpellier: 2001 IEEE Inter na tional Confer ence o n Robo tics and U niv er site M ontpellie r II, April 24, 1991. Auto mation, Seo ul, Ko rea , 2001: 2448 2453.。

空心砖烧成中常见的问题

2015年第7期新浪微博：砖瓦杂志社墙材网 2015Brick &Tile 空心砖烧成中常见的问题崔群星(河南省新安县铁门镇龙涧村四组，河南新安471832)摘要:详细分析了空心砖在生产中常出现的问题，并提出了相应的解决方法。

关键词:制品缺陷；产能低下；规范操作如今墙体材料由以往的实心砖向多孔砖空心砌块转换，这已成为当前行业的大势所趋。

空心砖以节约资源，提高保温、隔音性能以及砌筑效率等方面优于实心砖，从而逐渐取代了实心砖在墙材界的主导地位。

一些企业在生产空心砖的过程中，出现了这样那样的问题，对产能和砖质量构成了较大的影响。

下面对常见的问题以及解决方案做些分析。

1缺乏强度砖制品出窑后抗压、抗折性能偏差，哑音、脆酥状况明显，即使火度充足的制品也不例外。

1.1原因及解决方案砖坯干燥的早期升温过急或风压偏大所致，由于空心砖属于薄壁类制品，干燥早期如果升温过急和排潮风压偏大坯体迅速地被加热膨胀，很快的脱水，则砖裂纹或隐形裂纹增加，破坏了坯体原有的韧性与强度。

入窑焙烧时预热制度欠妥，空心砖在焙烧的预热阶段升温应平缓些。

这要在放长预热带长度，合理使用哈风闸形上下功夫，比如，焙烧带应向后移动些，哈风闸要使用桥形结构。

坯体含水率偏高，当入窑坯块含水率偏高时易使某些坯块在预热阶段返潮，从而破坏了坯体原有的强度。

另外，较湿的坯块对垛体正常的升温也会构成影响，砖垛移动至高温窑段时又遭遇快速的升温，从而导致制品强度下降。

2碎砖、断砖率高出窑的制品在卸车时有些呈现出碎块或半截砖，首先要查清在哪个环节出了问题，然后对症下药制定出改进方案。

制坯泥料成分中骨料和细料配方不妥，比例失当，缺乏应有的陈化时间等等，挤出的坯块就会呈现出不密实状态。

另外砖机的挤出压力与码坯层数不相匹配，或挤出时泥料含水量过大。

这样中下部的坯块碎坯、断坯就较多。

刚挤出成型数小时内过于频繁的移动湿坯车以及在摆渡车上剧烈的颠簸，也会造成中图分类号：TU522.064文献标识码：A 文章编号：1001-6945（2015）07-0043-02图1断砖技术交流Common problems in firing perforated bricksAbstract:The paper analyzes the common problems occurred in the production of porous bricks,and proposes methods to come up with appropriate solutions.Key Words:product defect;low capacity,standard operationCUI Qun-xing432015年第7期新浪微博：砖瓦杂志社墙材网2015Brick &Tile 不同程度的断砖。

The use of probiotics in aquaculture

Ž.Aquaculture1801999147–165www.elsevier.nl r locate r aqua-onlineReviewThe use of probiotics in aquacultureF.J.Gatesoupe)´Unite Mixte de Nutrition des Poissons INRA-IFREMER,IFREMER,Centre de Brest,BP70,F-29280´Plouzane,FranceAccepted12April1999AbstractThe research of probiotics for aquatic animals is increasing with the demand for environment-friendly aquaculture.The probiotics were defined as live microbial feed supplements that improve health of man and terrestrial livestock.The gastrointestinal microbiota of fish and shellfish are peculiarly dependent on the external environment,due to the water flow passing through the digestive tract.Most bacterial cells are transient in the gut,with continuous intrusion of microbes coming from water and food.Some commercial products are referred to as probiotics,though they were designed to treat the rearing medium,not to supplement the diet.This extension of the probiotic concept is pertinent when the administered microbes survive in the gastrointestinal tract. Otherwise,more general terms are suggested,like biocontrol when the treatment is antagonistic to pathogens,or bioremediation when water quality is improved.However,the first probiotics tested in fish were commercial preparations devised for land animals.Though some effects were observed with such preparations,the survival of these bacteria was uncertain in aquatic environ-ment.Most attempts to propose probiotics have been undertaken by isolating and selecting strains from aquatic environment.These microbes were Vibrionaceae,pseudomonads,lactic acid bacteria, Bacillus spp.and yeasts.Three main characteristics have been searched in microbes as candidatesŽ.to improve the health of their host.1The antagonism to pathogens was shown in vitro in most Ž.Ž.cases.2The colonization potential of some candidate probionts was also studied.3Challenge tests confirmed that some strains could increase the resistance to disease of their host.Many other beneficial effects may be expected from probiotics,e.g.,competition with pathogens for nutrients or for adhesion sites,and stimulation of the immune system.The most promising prospects are sketched out,but considerable efforts of research will be necessary to develop the applications to aquaculture.q1999Elsevier Science B.V.All rights reserved.Keywords:Microbial ecology;Digestive tract;Feed additives;Disease control;Antibacterial activity;Water quality)Tel.:q33-2-9822-4389;fax:q33-2-9822-4653;E-mail:joel.gatesoupe@ifremer.fr0044-8486r99r$-see front matter q1999Elsevier Science B.V.All rights reserved.Ž.PII:S0044-84869900187-8()148F.J.Gatesoupe r Aquaculture1801999147–1651.IntroductionLong before their discovery,microbes have been unawarely used to preserve food,Ž. and these empirical methods contributed to improve human health Bengmark,1998.Ž.Ž.Early in the century,Metchnikoff1907,1908cited by Tannock,1997proposed to implant lactic acid bacteria into the human intestine,with a view to suppressing the detrimental activity of other microbes.The modern concept of probiotics was formulated Ž.only25years ago Parker,1974,then its pertinence was challenged for many years among the scientific community.Several definitions of probiotics were successively Ž.proposed.Parker1974originally referred to‘‘organisms and substances which con-tribute to intestinal microbial balance’’as probiotics.The definition was then restricted to‘‘a live microbial feed supplement which beneficially affects the host animal byŽ.Ž. improving its intestinal microbial balance’’Fuller,1989.Tannock1997noted that the effect on the‘‘intestinal microbial balance’’has not been demonstrated in most cases,and he proposed to speak of‘‘living microbial cells administered as dietary supplements with the aim of improving health’’.To my knowledge,the first application of probiotics in aquaculture seems relatively Ž.recent Kozasa,1986,but the interest in such environment-friendly treatments is increasing rapidly.Scientific evaluation corroborated seldom the first empirical trials, and the information was mainly spread by‘‘grey literature’’.However,a growing number of scientific papers have dealt explicitly with probiotics,and it is now possible to survey the state of the art,from the empirical use to the scientific approach.AŽprevious review was devoted to lactic acid bacteria in finfish Ringøand Gatesoupe, .1998,but many other microbes have been tested as probiotics for various aquatic animals,appealing for a general overview.It is essential to remind some definitions of ecological concepts to clear away theŽ. treatments termed improperly‘‘probiotic’’.The goals of this paper are1to examineŽ.the pertinence of such terminology applied to the aquatic environment,2to draw theŽ.different trends of applications,and3to point out needs for further research.2.Is the intestinal environment of aquatic animals favourable to probiotics?Aquatic animals are quite different from the land animals for which the probiotic concept was developed,and a preliminary question is the pertinence of probiotic applications to aquaculture.Man and terrestrial livestock undergo embryonic development within an amnion, whereas the larval forms of most fish and shellfish are released in the external environment at an early ontogenetic stage.These larvae are highly exposed to gastro-intestinal microbiota-associated disorders,because they start feeding even though theŽ.digestive tract is not yet fully developed Timmermans,1987,and though the immuneŽ.system is still incomplete Vadstein,1997.Thus,probiotic treatments are particularly desirable during the larval stages.()F.J.Gatesoupe r Aquaculture1801999147–165149Gram-positive obligate or facultative anaerobes are dominant in the gastrointestinalŽ. microbiota of man and terrestrial farm animals Gournier-Chateau et al.,1994.Inhuman feces,the major bacterial groups are Bacteroides,Gram-positive anaerobic cocci,Ž.Eubacterium,and Bifidobacterium Hume,1997,whereas the predominant groups inŽ.pig feces are‘‘streptococci’’and‘‘lactobacilli’’Stewart,1997.Most probionts belongto dominant or sub-dominant genera among these microbiota,e.g.,Bifidobacterium,Ž.Lactobacillus,Streptococcus Gournier-Chateau et al.,1994.Gram-negative facultativeanaerobes prevail in the digestive tract of fish and shellfish,though symbiotic anaerobesŽmay be dominant in the posterior intestine of some herbivorous tropical fish Clements, .Ž1997.Vibrio and Pseudomonas are the most common genera in crustaceans Moriarty, .Ž.Ž.1990,marine fish Sakata,1990and bivalves Prieur et al.,1990.Aeromonas,Ž. Plesiomonas and Enterobacteriaceae are dominant in freshwater fish Sakata,1990.Aconsequence of the specificity of aquatic microbiota is that the most efficient probioticsfor aquaculture may be different from those of terrestrial species.The resident microbes benefit from a fairly constant habitat in the gastrointestinaltract of man and terrestrial livestock,whereas most microbes are transient in aquatic Ž.animals Moriarty,1990.These animals are poikilothermic,and their associated micro-Ž.´biota may vary with temperature changes Lesel,1990.Salinity changes may also Ž. influence microbiota Hamid et al.,1978;Sakata et al.,1980;Ringøand Strøm,1994,and marine finfish are obliged to drink constantly to prevent water loss from the body.This continuous water flow increases the influence of the surrounding medium,in thesame way as the water flow observed in filter-feeders,like bivalves,shrimp larvae andlive food organisms.This influence is particularly important in larvae,when the gastricbarrier is absent.Therefore,the intestinal microbiota of aquatic animals may changerapidly with the intrusion of microbes coming from water and food.In bivalves,theŽassociated microbiota is very similar to those found in seawater and sediment Sugita et.al.,1981;Prieur et al.,1990.The same kinds of bacteria were found in the gut ofPenaeus japonicus and in seawater,but normal members of microbiota may beŽ.introduced via the diet Moriarty,1990.In larval and juvenile fish,the influence of foodŽ. has been clearly demonstrated Tanasomwang and Muroga,1989;Ringøet al.,1995. The influence of bacteria brought by live food organisms is particularly dramatic during Ž.first feeding Munro et al.,1993;Bergh et al.,1994.3.Applications of the‘‘probiotic’’concept in a broad senseThe transience of aquatic microbes may legitimate the extension of the probioticŽ. concept to living microbial preparations used to treat aquaculture ponds.Moriarty1998 proposed to extend the definition of probiotics to microbial‘‘water additives’’.How-Ž.ever,this extension would make too vague definition of Tannock1997.I suggest analternative definition of probiotics as:microbial cells that are administered in such a wayas to enter the gastrointestinal tract and to be kept alive,with the aim of improvinghealth.This latter definition will be used in the following to sort the microbialpreparations which can be designated as probiotics.()150F.J.Gatesoupe r Aquaculture1801999147–165In1991,Porubcan reported on two attempts at bacterial treatments to improve waterŽ.quality and production yield of Penaeus monodon.1Floating biofilters pre-inoculated with nitrifying bacteria decreased the amounts of ammonia and nitrite in the rearingŽ.Ž.water.This treatment increased shrimp survival Porubcan,1991a.2The introduction of Bacillus spp.in proximity to pond aerators reduced chemical oxygen demand,andŽ.increased shrimp harvest Porubcan,1991b.Several commercial products have sought to exploit the same idea that bacteria which improve water quality may be beneficial to Žanimal health e.g.,‘‘bacteria’’,Aquatic Warehouse,San Diego,CA;‘‘Biostart’’, Advanced Microbial Systems,Shakopee,MN;‘‘BRF-1A,BRF-13A,PB-32,PBL-44’’, Enviro-Reps International,Camarillo,CA;‘‘Liqualife’’,Cargill,Animal Nutrition Divi-sion;‘‘microbial and enzymic products’’,Alliance Bioremediation and Composting, Encinitas,CA;‘‘PondPro-VC’’,Biomanagement Systems,Wellington Point,Australia;.‘‘probiotics’’,Contessa,ZB Industries,San Pedro,CA.These products are referred to as‘‘probiotics’’and most of them contain nitrifying bacteria and r or Bacillus spp. These two kinds of bacteria are quite different.The nitrifying bacteria have strict ecological niches,and they have not been detected in the gastrointestinal tract of animals.The strains of Bacillus ed as probiotics for terrestrial livestock have telluric origins,and they are not autochthonous in the gastrointestinal tract,but they mayŽ.be active during intestinal transit Gournier-Chateau et al.,1994.Moreover,there areŽmany reports of isolation of Bacillus strains from fish Hamid et al.,1978;Strøm and Olafsen,1990;Nedoluha and Westhoff,1995;Sadhukhan et al.,1997;Kennedy et al.,.Ž1998;Sugita et al.,1998,crustaceans Austin and Allen,1982;Sharmila et al.,1996;.Ž.Ž. Sugita et al.,1996a,and bivalves Sugita et al.,1981.Queiroz and Boyd1998 confirmed that a commercial inoculum of Bacillus spp.increased survival and produc-tion of channel catfish,but these authors focused their attention on water quality criteria,Ž.which were poorly affected by the treatment.Kennedy et al.1998isolated a strain of Bacillus subtilis from the common snook,Centropomus undecimalis.The inoculation of this strain into the rearing water resulted in the apparent elimination of Vibrio sp.from whole larvae of snook,after decreasing salinity from ca.30to ca.3practical salinity Ž.units.Moriarty1998noted an increase of prawn survival in ponds where some strains of Bacillus spp.were introduced.This treatment decreased the proportion of pathogenic luminous Vibrio spp.in the sediments,and to a lesser extent,in the water.The effect on prawn intestinal microbiota was not studied.The strains of Bacillus were selected because of their antibiotic activity against luminescent Vibrio sp.,but the author emphasized the multiplicity of the possible probiotic effects,e.g.,enzymatic excretions, competition for nutrients and for space.These various mechanisms of action might prevent the emergence of resistant strains,a well-known risk of antibiotic treatments. However,these speculations need to be confirmed by experimental evidence,in particu-lar,the reference to the principle of competitive exclusion,frequently put forward in advertisements for probiotics.This principle is based on the observation that experi-ments in chemostats‘‘usually result in the replacement of all members of an initial community by one organism best adapted to those highly selective substrate-limited Ž.growth conditions’’Dolfing and Gottschal,1997.The antibiotic activity of the strains of Bacillus would interfere,making uneasy to demonstrate competitive exclusion in thisŽ.case.The actual data of Moriarty1998showed the inhibitory activity of Bacillus spp.()F.J.Gatesoupe r Aquaculture1801999147–165151 against luminous Vibrio sp.in pond sediment,but the effect on prawn survival might be due either to a probiotic effect,or to an indirect effect on animal health.For instance,the degradation of organic matter by Bacillus spp.might improve water quality.Therefore, the use of Bacillus spp.as pond supplement needs further investigation to be considered as a probiotic treatment,with particular attention to a possible intestinal transience.The probiotic treatments may be considered as methods of biological control,the so-called‘‘biocontrol’’that termed the limitation or the elimination of pests by the introduction of adverse organisms,like parasites or specific pathogens.Maeda et al.Ž.1997proposed to designate as biocontrol the methods of treatment using‘‘theŽ.antagonism among microbes...through which pathogens can be killed or reduced in number in the aquaculture environment’’.In this acceptation,the pond treatmentŽ.proposed by Moriarty1998is indisputably relevant to biocontrol,as well as many other microbial treatments,including those whose target organisms are not animals,but Ž.microalgae Rico-Mora et al.,1998.Another terminology should designate the applica-tions of nitrifying bacteria that are related to the bioremediation concept.This concept refers to the treatment of pollutants or waste by the use of microorganisms that breakŽ.down the undesirable substances Fig.1.The same concept is sometimes named Ž.bioaugmentation Moriarty,1997,1998.Fig.1.Tentative classification of microbial treatments used in aquaculture,according to current terminology.Ž. The term‘‘probiotics’’is reserved to strains transient or resident in the gastrointestinal tract Section3,Ž.‘‘biocontrol’’implies only that the strains are antagonistic to pathogens Maeda et al.,1997,and‘‘bioremedi-Ž.ation’’refers to breakdown of pollutants or waste by the microbes Moriarty,1997,1998.()152F.J.Gatesoupe r Aquaculture1801999147–1654.Application of commercial products for terrestrial livestockThe first trials of incorporation of probiotics into aquaculture feeds used commercialpreparations designed for land animals.Spores of Bacillus toyoi isolated from soilŽreduced the mortality of Japanese eel which were infected by Edwardsiella sp.,Kozasa, .Ž. 1986.The same feed additive increased the growth rate of yellowtail Kozasa,1986.Spores may be easily incorporated into compound food,but their fate in the gastrointes-tinal tract of fish was not followed in these experiments.It would be particularlyinteresting to know whether the spores may germinate in the gut,depending on transitŽ. time and rearing temperature.The same strain of B.toyoi used by Kozasa1986was later tested on rotifers,Brachionus plicatilis,which were left to filter the spores for2h Ž.Gatesoupe,1989.This treatment increased the growth rate of larval turbot,but themicrobiota were studied neither in the larvae nor in the ter,a study wasperformed with the food additive‘‘Paciflor9’’containing spores of Bacillus IP5832bycounting and characterising bacteria associated with spore-fed rotifers and turbot larvae Ž.Gatesoupe,1993.Most spores of Bacillus sp.were filtered by the rotifers within lessthan half an hour,but the number of cultivable cells of the strain decreased sharply inthe rotifers1h after introduction of the spores into the water.These cells were thusrecovered alive in the rotifers,but for a period probably too short to allow an actualŽ.probiotic effect,according to the definition suggested above Section3.Many bacilliŽ. produce antibiotics,especially in relation to the sporulation process Brock,1974,andŽsome antibiotics may be produced by proteolysis of the vegetative cells Vitkovic and .Sadoff,1977.When rotifers were fed with spores,the decrease of the Vibrionaceaenormally dominant in the rotifers might be due to such a release of antibiotic from the Ž.cells of Bacillus sp.Gatesoupe,1993.Few cultivable cells of the strain of Bacillus sp.were recovered from turbot fed for five days with the spore-treated rotifers.A directprobiotic effect was therefore unlikely,though this treatment increased the resistance ofturbot larvae exposed to pathogenic Vibrio sp.Commercial preparations with live lactic acid bacteria have also been introduced intothe medium of live food organisms for larval flatfish.Some of these treatmentsincreased the production of rotifers and the growth of turbot and Japanese flounder Ž.Gatesoupe,1989,1991;Gatesoupe et al.,1989.Some preparations with lactic acidbacteria limited also the proliferation of bacteria in rotifers,but the fate of the lactic acidŽ. bacteria was not studied in these experiments Gatesoupe et al.,1989;Gatesoupe,1991. Other commercial preparations of Streptococcus faecium improved the growth and feedŽ.efficiency of Israeli carp Noh et al.,1994;Bogut et al.,1998.Escherichia colidisappeared from the intestinal microbiota of carp after14days of feeding with theŽ.probiotic preparation Bogut et al.,1998.These authors stated that S.faecium‘‘hashigh adhesive ability in the epithelium of carp digestive tract’’,but without anyexperimental evidence.These trials with commercial probiotics for land animals were important to show theinterest of bacterial additives in aquaculture feeds,but the survival of these microbeswas uncertain in the gastrointestinal tract of aquatic animals.Most attempts have beenafterwards aimed at seeking autochthonous strains with probiotic properties.()F.J.Gatesoupe r Aquaculture1801999147–1651535.The search for autochthonous aquatic probiotics5.1.Isolation and characterization of autochthonous microbesIn juvenile fish and shellfish,the autochthonous microbes may be isolated from the digestive tract after dissection,while distinguishing stomach and intestine regions.The microbes adherent to epithelial cells can be separated from those adherent to mucus,andŽ.from those transient in the lumen Westerdahl et al.,1991.These methods are not applicable to larvae and live food organisms,but the external surface of larval fish may be washed with a0.1%benzalkonium chloride saline solution to differentiate theŽmicrobes adherent to the external surface from those present in the gut Blanch et al., .Ž1997.Many microbes may be isolated on selective media Pratt and Reynolds,1973;.Flint,1985;Jeppesen,1995;Donovan and van Netten,1995.Then the isolates areŽcharacterized by proper methods Roth et al.,1962;Hansen and Sorheim,1991;Holt et.al.,1994;Bertone et al.,1996;Austin et al.,1997;Tannock,1999.5.2.Pioneering studiesŽ.The first successful report seems to be attributed to Maeda and Liao1992,who isolated a strain‘‘PM-4’’from the rearing water of larval Pen.monodon,with goodŽsurvival and molting rate.The bacterium,identified as Thalassobacter utilis Nogami et .Žal.,1997,was used for the biocontrol of the larval rearing of Pen.monodon Maeda.and Liao,1992;Maeda et al.,1997and the swimming crab,Portunus trituberculatus Ž.Nogami and Maeda,1992;Nogami et al.,1997.This biocontrol treatment increasedŽthe survival of the larvae,and repressed the growth of Vibrio anguillarum Nogami and .Ž. Maeda,1992and Haliphthoros sp.fungus,Lagenidales;Nogami et al.,1997.It would be worth studying whether T.utilis can survive in the gut of the larval crab,sinceŽV.anguillarum infection can start via the intestinal route Colorni,1985;Grisez et al.,.1996;Olsson et al.,1996;Garcia et al.,1997.Ž.Griffith1995reported that shrimp larvae reared in Ecuadorian hatcheries were affected by a disease characterized by a change in the bacterial population.The proportion of Vibrio alginolyticus decreased,whereas Vibrio parahaemolyticus in-creased.The strain of V.alginolyticus was isolated and used as probiotic in many hatcheries,where shrimp survival was restored to the level obtained before diseaseŽ.outbreak.Austin et al.1995investigated the probiotic effect of this strain,and these authors reported that cells of Vibrio ordalii lost their viability within3h after the introduction of freeze-dried supernatant of probiotic culture into the suspension medium. V.anguillarum and Aeromonas salmonicida were also inhibited,but to a lesser extent. The probiont survived in the intestine of Atlantic salmon for at least3weeks,and a preliminary bath with this probiont improved the survival of salmon challenged withŽ. pathogens.This provides an example of what might be expected from probiotics:1Ž.antagonism to pathogens,2gut colonization,with possible adhesion to intestinal Ž.mucus,and3increased resistance of the host to pathogens.()154F.J.Gatesoupe r Aquaculture1801999147–1655.3.Antagonism to pathogensŽ.Antagonism seems to be common among marine bacteria Table1.For example,Ž.over60%of isolates from zooplankton were bacteriolytic Nair et al.,1985,and up toŽ75%of the isolates from sponges produced antibacterial compounds Marty and Martin, .Ž. 1992.A pathogenic Vibrio sp.was inhibited by a variable proportion0–100%of theŽ.bacteria isolated from first-feeding halibut larvae Bergh,1995.Most marine ant-Table1Antagonism of aquatic microbes to fish and shellfish pathogens.Ae.:Aeromonas;Ae.h.:Ae.hydrophila; Ae.s.:Ae.salmonicida;Ed.t.:Edwardsiella tarda;En.s.:Enterococcus seriolicida;IHNV:infectious hemato-poietic necrosis virus;OMV:Onchorhynchus masou virus;Ps.d.:Ps.doudorofii;Pa.p.:Pasteurella piscicida;V.:Vibrio;V.al.:V.alginolyticus;V.an.:V.anguillarum;V.o.:V.ordalii;Y.r.:Yersinia ruckeri Antagonist Source Pathogens tested ReferenceŽ. Freshwater bacteria fish intestine Aeromonas spp.Sugita et al.,1996bŽ. Freshwater bacteria salmonid hatchery IHNV Kamei et al.,1988Ž. Marine bacteria invertebrates Vibrio spp.Marty and Martin,1992Ž. Marine bacteria seaweeds Ed.t.,Pa.p.,Ae.spp.,Dopazo et al.,1988V.spp.,Y.r.Ž. Marine bacteria Scophthalmus maximus Ae.h.,Ae.salmonicida,V.an.Westerdahl et al.,1991Ž. Marine bacteria various Ae.h.,V.an.Ivanova et al.,1998Ž. Marine bacteria various En.s.;Pa.p.;V.an.;Sugita et al.,1996aVibrioÕulnificusŽ. Marine bacteria various IHNV Kamei et al.,1987Ž. Marine bacteria various‘‘V.anguillarum-related’’Riquelme et al.,1997Ž. Aeromonas media seawater Ae.spp.,V.spp.,Y.r.Gibson et al.,1998Ž. Alteromonas Argopecten purpuratus Ae.h.,V.al.,V.an.,V.o.Riquelme et al.,1996 haloplanktisŽ. Alteromonas sp.Palaemon macrodactylus Lagenidium callinectes Gil-Turnes et al.,1989Ž. Alteromonas sp.Pecten maximus Ps.d.,Pa.p.,Vibrio spp.Ruiz et al.,1996Ž. Alteromonas-like Pen.monodon hatchery Vibrio spp.Tanasomwang et al.,1998Ž. Bacillus sp.Callionymus sp.V.Õulnificus Sugita et al.,1998Ž. Carnobacterium Salmo salar V.an.,V.salmonicida Strøm,1988diÕergensŽ.¨Carnobacterium sp.Sa.salar Ae.s.,V.an.Joborn et al.,1997Ž. Lactococcus lactis Br.plicatilis V.anguillarum Shiri Harzevili et al.,1998Ž. Lactobacillus sp.Paralichthys oliÕaceus Ae.h.,Ed.t.,Pa.p.,V.an.Byun et al.,1997Ž. Pseudoalteromonas marine environment IHNV,V.an.Maeda et al.,1997 undinaŽ.Ps.fluorescens Lates niloticus V.anguillarum Gram et al.,1999Ž. Ps.fluorescens Salmo trutta Ae.salmonicida Smith and Davey,1993Ž. Roseobacter sp.Pec.maximus Ae.sp.,Ps.d.,Vibrio spp.Ruiz-Ponte et al.,1998Ž.T.utilis Pen.monodon Haliphthoros sp.Nogami et al.,1997Ž. T.utilis Pen.monodon V.anguillarum Nogami and Maeda,1992Ž. V.alginolyticus Pen.monodon Vibrio harÕeyi Ruangpan et al.,1998Ž.V.alginolyticus shrimp hatchery Ae.s.,V.an.,V.o.,Y.r.Austin et al.,1995Ž.Vibrio spp.marine environment V.parahaemolyticus Nair et al.,1985ŽVibrio spp.shrimp hatchery IHNV,OMV Direkbusarakom et al.,.1998Ž. Vibrionaceae Hippoglossus hippoglossus Vibrio sp.Bergh,1995()F.J.Gatesoupe r Aquaculture1801999147–165155agonistic strains are members of the Pseudomonas–Alteromonas and r or Vibrio groups Ž.Lemos et al.,1985;Nair et al.,1985.Antibacterial activity is also common inŽ.freshwater microbiota Sugita et al.,1996b.Some lactic acid bacteria,such as Ca.ŽdiÕergens and Lactobacillus sp.are antagonistic to fish pathogens Strøm,1988;Byun.Ž.¨et al.,1997;Joborn et al.,1997.Sugita et al.1998isolated a strain of Bacillus sp.that was antagonistic to63%of the isolates from fish intestine.Pathogenic strains of Vibrio or Aeromonas have been targeted in most in vitro tests,but some other fish pathogensŽwere also tested,e.g.,Ed.tarda,En.seriolicida,Pa.piscicida,Y.ruckeri Dopazo et al.,1988;Austin et al.,1995;Ruiz et al.,1996;Sugita et al.,1996a;Byun et al.,1997;.ŽGibson et al.,1998.Some bacteria are antagonistic to viruses Kamei et al.,1987,1988;.Direkbusarakom et al.,1998,and they may be efficient for the biocontrol of viral Ž.diseases Maeda et al.,1997.It is important to remind that antagonism may be mediated not only by antibiotics, but also by many other inhibitory substances,for example:organic acids,hydrogen Ž.Žperoxide reviewed by Ringøand Gatesoupe,1998,siderophores Gram and Mel-.chiorsen,1996.The inhibition due to such compounds is highly dependent on the experimental conditions,which are different in vitro and in vivo.Therefore,the expression of antagonism in vitro is not a sufficient criterion to select candidate Ž.probiotics Riquelme et al.,1997,nor is sufficient the absence of antagonism to rule the Ž.strains out Rico-Mora et al.,1998.5.4.Intestinal colonization and transienceThe colonization potential is another important criterion to characterize probiotics, but transient bacteria may be also efficient if the cells are introduced at high dose,Ž.continuously or semi-continuously Gournier-Chateau et al.,1994.In practice,it isŽ. therefore essential to evaluate the persistence of the probiotic in the gut Table2.TheŽexperimental introduction of lactic acid bacteria has been already reviewed Ringøand .Gatesoupe,1998.The concentration of Ca.diÕergens was higher in the pyloric caecaŽ.than in the intestine of Atlantic cod juveniles Gildberg and Mikkelsen,1998.Isolates of lactic acid bacteria seemed able to survive for several days in the intestine of larval Ž.¨and juvenile fish Strøm and Ringø,1993;Joborn et al.,1997.Vibrionaceae may alsoŽpersist for days or weeks in fish Austin et al.,1995;Munro et al.,1995;Ringøand .Ž. Vadstein,1998and in Pacific oyster larvae,Cr.gigas Gibson et al.,1998.YeastsŽ.seemed particularly persistent in rainbow trout Andlid et al.,1995.Adhesion to intestinal mucus was also assayed in vitro.Such tests indicated that Carnobacterium sp.adhered indifferently to the intestinal mucus of rainbow trout or toŽ.¨control surface treated with bovine serum albumin Joborn et al.,1997.Autochthonous intestinal bacteria of turbot seemed to adhere specifically to intestinal mucus,since their adhesion potential was stronger to mucus than to control surface,whereas bacteriaŽ.isolated from skin mucus were poorly adhesive Olsson et al.,1992.Yeasts also adhereŽ.to the intestinal mucus of rainbow trout Vazquez-Juarez et al.,1997,and theŽ. involvement of specific adhesins has been demonstrated Vazquez-Juarez,1996.Yeasts have therefore a great potential to adhere and to colonize the intestine of fish,and their application as probionts in aquaculture deserves more attention.。

Probability Theory

Contract no:BAP098M-RG-15-MedProbability TheoryJ.M.SteeleWhartonProbability theory is that part of mathematics that aims to provide insight into phe-nomena that depend on chance or on uncertainty.The most prevalent use of the theory comes through the frequentists’interpretation of probability in terms of the outcomes of repeated experiments,but probability is also used to provide a measure of subjective beliefs,especially as judged by one’s willingness to place bets.The roots of probability theory are not as ancient as those of many parts of math-ematics,and only in the sixteenth and seventeenth centuries does oneﬁnd theﬁrst glimmerings of the theory in the investigations made by Gerolamo Cardano,Pierre de Fermat,and Blaise Pascal into games of chance.Despite the luminous reputa-tions of these famous mathematicians and philosophers,the subject of probability theory remained on the periphery of respectability,and for a long time development was halting and lugubrious.Through theﬁrst third of the twentieth century,the eighteenth century works of Jakob Bernoulli(see Bernoulli Family)and Abraham De Moivre continued to be viewed as the nearly deﬁnitive treatises of probability theory.Int.Encyc.Social and Behavioral Sciences18March2003Still,even in the early days of the twentieth century when probability theory clearly suffered from the lack of a widely accepted foundation,there were profound devel-opments,most notably Albert Einstein’s use of Brownian motion in1905to pro-vide theﬁrst determination of Avagadro’s number[7].Nevertheless,in1933when Andrey Nikolayevich Kolmogorov published his elegant succinct volume Founda-tions of Probability Theory[10],the mathematical world was hungry for such a treatment,and the subsequent development of probability theory was explosive.1Firm FoundationCentral to Kolmogorov’s foundation for probability theory was his introduction of the triple(Ω,F,P)that we now call a probability space,or sometimes the“proba-bilist’s trinity”.The triple’sﬁrst element,Ω,is required only to be a set.The second element is a collection of subsets ofΩabout which more will be said later.The third element is a function that assigns a real number to each of the elements of F.This function is called a probability measure P provided that it satisﬁes the three fol-lowing axioms:Axiom1.For all A∈F we have P(A)≥0.Axiom2.For any countable collection{A i∈F:1≤i<∞}for which A i∩A j= for all i=j,we haveP(∪∞i=1A i)=∞i=1P(A i).Axiom3.P(Ω)=1Axioms1and3are quite bland.Axiom1only captures our understanding that probabilities of events are nonnegative numbers,and Axiom3 just echoes our assumption thatΩis a sensible representation for the universe of all possible outcomes of the chance experiment being modeled.Only about Axiom2 can there can be any quarrel,and at times arguments have been made for preferring a probability theory that only requires additivity of probabilities forﬁnite collec-tions of sets.Kolmogorov’s decision to assume countable additivity is not the only possible choice,but it has been a fecund one that has proved to be appropriate in a wide variety of circumstances.The mathematical beneﬁt of Kolmogorov’s second axiom is that it connects proba-bility theory with the theory of measure as put forward by Borel,Lebesgue,Radon, and Fr´e chet in the early part of the twentieth century.It was in fact Fr´e chet who noted some13years after Lebesgue’s famous1902thesis that the natural domain for a probability measure is a collection of sets that is closed under complemen-tation and countable unions.Fr´e chet called such collectionsσ-algebras,and Kol-mogorov required that the second term of his triple be just such a collection.2Basic Quantities of the TheoryTo the practical mind,Kolmogorov’s axiomatization of probability may seem only to defer the problem of construction of probability models that serve to inform us about the physical and social world,but by putting the elusive probability function P on an axiomatic footing Kolmogorov did provide real assurance that one couldstudy probability as sensibly as one could study measure theory,analysis or algebra. In particular,one could proceed with the investigation of the objects that had been of concern from probability’s earliest days.One of the most fundamental notions of probability theory is the random variable, and in Kolmogorov’s framework a random variable is nothing more than a function from X:Ω→ with the property that for all t one has that the sets{ω:X(ω)≤t}are elements of theσ-algebra F.With this deﬁnition we are onﬁrm footing when we take the deﬁnition of the distribution function F of X to beF(t)=P(X≤t),because the set{ω:X(ω)≤t}is in the domain of the set function P.In this frame-work the expectation E(X)of the random variable X can deﬁned as the Lebesgue integral of X with regard to P,or as the Riemann-Stieltjes integral with respect to F,giving usE(X)ΩX(ω)d P(ω)=∞−∞xd F(x).The probability distribution function and the expectation operation provide us with the core language that is needed to express almost everything that one needs to say about individual random variables.For example,a basic measure of dispersion of a random variable is the variance,which one writes in terms of the expectation asvar(X)−E(X−µ)2,whereµ=E(X)and the standard deviation of X is deﬁned to be the square root of the variance.3Central Role of IndependenceWith expectations and distributions we recapture much of the most basic language of probability theory,but the real power of probability theory only emerges with the introduction of the central notion of independence of events,algebras,and random variables.To begin that development,oneﬁrst deﬁnes elements A and B of F to be independent providedP(A∩B)=P(A)P(B).This deﬁnition is then extended to sub-σ-algebras of A and B of F by calling A and B independent provided A and B are independent for all A∈A and all B∈B. Finally,random variables X and Y are independent if A and B independent when these are respectively the smallestσ-algebras containing all the sets{X≤t}and all the sets{Y≤t}.This deﬁnition of independence of random variables may look a little burdensome atﬁrst,but for many purposes it is much more convenient than the deﬁnition of independence that is sometimes given in elementary texts that call for the factor-ization of the joint density of X and Y.In fact densities may not exist,but that is not the telling point.More to the heart of the matter is that with Kolmogorov’s deﬁ-nition one clearly sees that the independence of X and Y implies the independence of f(X)and g(Y)for any monotone functions f and g,while this intuitive fact is cumbersome to check if one needs to verify a density factorization.4Theorems That Make the TheoryThere are two theorems that live at the very heart of probability theory.Theﬁrst is the law of large numbers,without which our most fundamental intuitions about the relationship of probability theory and the physical world would be at odds.The second is the central limit theorem,which is arguably the result that most clearly accounts for the practical utility of probability as a helpmate to statistics,as well as to the social and physical sciences.Theorem1(Law of Large Numbers).If{X i:1≤i<∞}is a sequence of independent random variables,with the distribution function,F,and if E|X i|<∞,then the event that the sequence1{X1+X2+...+X n}nconverges to E(X1)has probability one.Theorem2(Central Limit Theorem).If{X i:1≤i<∞}is a sequence of independent random variables with distribution function F,E(X i)=µ<∞,andvar (X )=σ2<∞,thenlim n →∞P (1α√n{X 1+X 2+...+X n −nµ}≤x )=1(2π)1/2 x −∞e −µ2/2du.5Beyond Independent Random VariablesWhile the purest view of the aims and accomplishments of probability theory may be found in the study of sums of independent random variables,the applications of probability theory require the development of structures that also capture aspects of dependence.To give the simplest illustration of a such a system,we consider a set ﬁnite set S ={1,2,...,n }which we will call the set of “states”,and a matrix P ={p ij ),where all of the matrix entries satisfy 0≤p ij ≤1and where the row sums p i 1+p i 2+...+p in all equal one.We now consider a sequence of random variables X n that are deﬁned by sequential transitions according to the row of the matrix P .Speciﬁcally,if X n =i ,then X n +1is determined by making a choice from the set S in accordance with the probability masses (p ij ).Such a sequence of random variables is called a Markov chain,and the theory of such sequences offers an important ﬁrst step from the core theory of independent random variables.The index of the sequence {X n :n ≥0}is usually viewed as “time”and an important extension of the notion of a Markov chain is that of a Markov Process where the index is taken to be the whole positive real line and the state space is permitted to be d (or even a more complex space).The most important such process is Brownianmotion.Another direction for the development of probability theory that goes beyond in-dependence is provided by the theory of martingales.On one level,martingales capture the notion of a fair gambling game,and although this view is interesting (and loyal to the origins of probability theory),the theory of martingales turns outto be an appropriate tool for many kinds of investigation(see Counting Process Methods in Survival Analysis).In particular,the theory of martingales provides the key to profound connections between the theory of Markov processes and the classical theory of harmonic functions.Referencesa)Adams,W.J.(1974).The Life and Times of the Central Limit Theorem,Kaed-mon Press,New York.b)Chung,K.L.(1974).Elementary Probability with Stochastic Processes.Springer-Verlag,New York.c)David,F.N.(1962).Games,Gods,and Gambling:The Origins and History ofProbability from the Earliest Times to the Newtonian Era.Grifﬁn,London.d)Doob,Joseph L.(1994).The development of rigor in mathematical proba-bility(1900-1950),in Development of Mathematics1900-1950,J.-P.Pier,ed.Birkhauser-Verlag,Basel.e)Dudley,R.M.(1989).Real Analysis and Probability.Wadsworth-Brooks/Cole,Paciﬁc Grove.f)Durren,R.(1991).Probability:Theory and Examples,Wadsworth-Brooks/Cole,Paciﬁc Grove.g)Einstein,A.(1905).On the movement of small particles suspended in a sta-tionary liquid demanded by the molecular-kinetic theory of heat(in German), Ann.Pys.(Ser.4)17,549–560.h)Feller,W.(1968).An Introduction to Probability and Its Applications.V ol.I,3rd Ed.Wiley,,New York.i)Kolmogorov,A.N.(1933).Grundbeggriffe der Wahrscheinlichtkeitrechnung..Springer-Verlag,Berlin.(English translation:N.Morrison(1956),Founda-tions of the Theory of Probability,Chelsea,New York.)j)Stigler,S.M.(1986).The History of Statistics:The Measurement of Uncer-tainty before1900.Harvard University Press,Cambridge,MA.(See also Axioms of Probability;Foundations of Probability)J.M.Steele。

不确定环境下飞行器航迹规划

根据环境的确定性程度, 飞行预规划可进一步划分为环境完全已知航迹规划和环境部分未知航迹规划。通常采用的环境建模方案和算法大多是针对
收稿日期: 2011-09-13 修回日期: 2011-11-21 作者简介: 王光源( 1964- ) , 男, 山东文登人, 博士, 副教
授, 研究方向: 兵种战术, 任务规划。
不确定威胁主要指事先侦察未曾探明的敌防空
高炮或地空导弹阵地, 对某一区域 Oi , 设区域圆中
心坐标为( x 0, y 0) , 区域半径为 R, 根据威胁存在概
率函数 p i 、威胁位置分布函数 p i( x ′, y ′) 、导弹、高炮
等武器系统威胁概率函数 P w ( d) , 对任意一点( x ,
p i ( x ′, y ′) =
1 R2
( x ′, y ′) ∈Oi
( 2)
0 ( x ′, y ′) Oi
1. 3 静态威胁概率函数 1. 3. 1 山体障碍威胁概率模型
山体障碍对飞行安全影响不言而喻, 一旦相撞, 机毁人亡, 故必须规避。在二维水平空间内, 山体障碍威胁可由飞行器巡航高度上的等高线所包围的区
在模型( 3) 、模型( 5) 、模型( 6) 中, 不同威胁的威
胁概率函数值在最大距离处为 0, 在最小距离处为
1, 函数连续且满足距离越小、威胁程度越大的原则,
较好地描述了各威胁源随距离变化的威胁概率分布
情况。航迹规划中, 针对不同威胁源性能及威胁程度
等差异, 可赋予不同的权重系数。
1. 4 不确定威胁概率函数模型
建立了威胁存在概率函数模型后, 对作战环境的整个区域都可用概率的形式来表示是否存在威
胁, 确定存在威胁的区域概率为 1, 确定不存在威胁的区域概率为 0, 对于可能存在威胁的某区域 i 用式 ( 1) 中 p i 来表示威胁存在于该区域的概率, 如图 1 所示。

Abstract. THE SYMMETRIC PROCRUSTES PROBLEM

Abstract.
"symmetric The following Procrustes" problem arises in the determination of the strain matrix of an elastic structure: find the symmetric matrix Xwhich minimises the Frobenius (or Euclidean) norm of AX-&, where '4 and .B are given rectangular matrices. We use the singular value decomposition to analyse the problem and to derive a stable method for its solution. A perturbation result is derived and used to assessthe stability of methods based on solving normal equations. Some comparisons with the standard, unconstrained least squares problem are given. 1980 Mathematics Subject Classification; Primary 65F20. Keywords: Least squares, symmetric Procrustes problem, singular value decomposition, normal equations.
/
\rt2
Received January 1987. Revised June 1987. r Procrustes: ancientGreek robber who tied his victims to an iron an bed, stretching their legs if too short for it, and lopping them if too long.

钡_聚乙二醇1000_四苯硼钠体系浊度法测定微量钡

钡-聚乙二醇1000-四苯硼钠体系浊度法测定微量钡李建平　刘　敏(桂林工学院应用化学系　桂林541004)魏小平(广西地质环境监测总站)摘　要　在HOA c 2N aOA c 缓冲溶液中,B a2+与聚乙二醇1000及四苯硼钠反应生成大分子三元络合物型沉淀,据此建立了测定微量钡的浊度分析新体系。

钡浓度在0～5.6Λg ・m l -1范围内符合比耳定律,检出限为0.04Λg ・m l -1。

方法具有灵敏、准确、简便、快捷,无须加入分散剂和体系稳定时间长等特点。

用于岩石土壤标样中微量钡测定,结果满意。

主题词　钡　浊度法　聚乙二醇　四苯硼钠N EPH ELOM ETR I C D ET ERM I NA T I ON O F M I CRO AM OU N T S O F BA R I UMW ITH PEG 1000AND SOD I UM T ETRA PH EN YLBO RA T EL i J i anp i ng and L iu M i n(D ep t .of A pp lied Che m istry ,Gu ilin Institu te of T echnology Gu ilin 541004)W e i X i aop i ng(Guang x i M onitoring Center f or Geolog ical E nv iro m ent )Abstract A nephelom etric m ethod is described fo r the deter m inati on of m icro amounts of barium based onthe fo r m ati on of m acromo lecule ternary comp lex of Ba 2+w ith PEG 1000and sodium tetraphenylbo rate in a HOA c 2N aOA c buffer so luti on (pH 5.0).Beer ′s law is obey in the concentrati on range of 0～5.6Λg of Ba 2+per m ililiter w ith a detecti on li m it of 0.04Λg ・m l -1.N o dispersing agent is needed .T he m ethod is sensitive ,accurate ,rap id and si m p le .It has been used fo r the deter m inati on of barium in rock and so il samp les w ith satisfacto ry results .Keywords Barium N ephelom etry PEG 1000　Sodium tetraphenylbo rate 微量钡的测定常采用光度法,所用显色剂多为偶氮类试剂[1～3],但这类试剂对二价及部分三价金属离子选择性差。

专八阅读真题

PART II READING COMPREHENSION (30 MIN)In this section there are four reading passages followed by a total of 20 multiple-choice questions. Read the passages and then mark your answers on your coloured answer sheet.TEXT AStill, the image of any city has a half-life of many years. (So does its name, officially changed in 2001 from Calcutta to Kolkata, which is closer to what the word sounds like in Bengali. Conversing in English, I never heard anyone call the city anything but Calcutta.) To Westerners, the conveyance most identified with Kolkata is not its modern subway—a facility whose spacious stations have art on the walls and cricket matches on television monitors—but the hand-pulled rickshaw. Stories and films celebrate a primitive-looking cart with high wooden wheels, pulled by someone who looks close to needing the succor of Mother Teresa. For years the government has been talking about eliminating hand-pulled rickshaws on what it calls humanitarian grounds—principally on the ground that, as the mayor of Kolkata has often said, it is offensive to see “one man sweating and straining to pull another man.” But these days politicians also lament the impact of 6,000 hand-pulled rickshaws on a modern city’s traffic and, particularly, on its image. “Westerner s try to associate beggars and these rickshaws with the Calcutta landscape, but this is not what Calcutta stands for,” the chief minister of West Bengal, Buddhadeb Bhattacharjee, said in a press conference in 2006. “Our city stands for prosperity and development.” The chief minister—the equivalent of a state governor—went on to announce that hand-pulled rickshaws soon would be banned from the streets of Kolkata.Rickshaws are not there to haul around tourists. (Actually, I saw almost no tourists in Kolkata, apart from the young backpackers on Sudder Street, in what used to be a red-light district and is now said to be the single place in the city where the services a rickshaw puller offers may include providing female company to a gentleman for the evening.) It’s the people in the lanes who most regularly use rickshaws—not the poor but people who are just a notch above the poor. They are people who tend to travel short distances, through lanes that are sometimes inaccessible to even the most daring taxi driver. An older woman with marketing to do, for instance, can arrive in a rickshaw, have the rickshaw puller wait until she comes back from various stalls to load her purchases, and then be taken home. People in the lanes use rickshaws as a 24-hour ambulance service. Proprietors of cafés or corner stores send rickshaws to collect their supplies. (One morning I saw a rickshaw puller take on a load of live chickens—tied in pairs by the feet so they could be draped over the shafts and the folded back canopy and even the axle. By the time he trotted off, he was carrying about a hundred upside-down chickens.) The rickshaw pullers told me their steadiest customers are schoolchildren. Middle-class families contract with apuller to take a child to school and pick him up; the puller essentially becomes a family retainer.From June to September Kolkata can get torrential rains, and its drainage system doesn’t need torrential rain to begin backing up. Residents who favor a touch of hyperbole say that in Kolkata “if a stray cat pees, there’s a flood.” During my stay it once rained for about 48 hours. Entire neighborhoods couldn’t be reached by motorized vehicles, and the newspapers showed pictures of rickshaws being pulled through water that was up to the pullers’ waists. When it’s raining, the normal customer base for rickshaw pullers expands greatly, as does the price of a journey. A writer in Kolkata told me, “When it rains, even the governor takes rickshaws.”While I was in Kolkata, a magazine called India Today published its annual ranking of Indian states, according to such measurements as prosperity and infrastructure. Among India’s 20 largest states, Bihar finished dead last, as it has for four of the past five years. Bihar, a couple hundred miles north of Kolkata, is where the vast majority of rickshaw pullers come from. Once in Kolkata, they sleep on the street or in their rickshaws or in a dera—a combination garage and repair shop and dormitory managed by someone called a sardar. For sleeping privileges in a dera, pullers pay 100 rupees (about $2.50) a month, which sounds like a pretty good deal until you’ve visited a dera. They gross between 100 and 150 rupees a day, out of which they have to pay 20 rupees for the use of the rickshaw and an occasional 75 or more for a payoff if a policeman stops them for, say, crossing a street where rickshaws are prohibited. A 2003 study found that rickshaw pullers are near the bottom of Kolkata occupations in income, doing better than only the ragpickers and the beggars. For someone without land or education, that still beats trying to make a living in Bihar.There are people in Kolkata, particularly educated and politically aware people, who will not ride in a rickshaw, because they are offended by the idea of being pulled by another human being or because they consider it not the sort of thing people of their station do or because they regard the hand-pulled rickshaw as a relic of colonialism. Ironically, some of those people are not enthusiastic about banning rickshaws. The editor of the editorial pages of Kolkata’s Telegraph—Rudrangshu Mukherjee, a former academic who still writes history books—told me, for instance, that he sees humanitarian considerations as coming down on the side of keeping hand-pulled rickshaws on the road. “I refuse to be carried by another human being myself,” he said, “but I question whether we have the right to take away their livelihood.” Rickshaw supporters point out that when it comes to demeaning occupations, rickshaw pullers are hardly unique in Kolkata.When I asked one rickshaw puller if he thought the government’s plan to rid the city of rickshaws was based on a genuine interest in his welfare, he smiled, with a quick shake of his head—a gesture I interpreted to mean, “If you are so naive as to ask s uch a question, I will answer it, but it is not worth wasting words on.” Some rickshaw pullers I met were resigned to the imminent end of their livelihood and pin their hopes on being offered something in its place. As migrant workers, they don’thave the political clout enjoyed by, say, Kolkata’s sidewalk hawkers, who, after supposedly being scaled back at the beginning of the modernization drive, still clog the sidewalks, selling absolutely everything—or, as I found during the 48 hours of rain, absolutely everything but umbrellas. “The government was the government of the poor people,” one sardar told me. “Now they shake hands with the capitalists and try to get rid of poor people.”But others in Kolkata believe that rickshaws will simply be confined more strictly to certain neighborhoods, out of the view of World Bank traffic consultants and California investment delegations—or that they will be allowed to die out naturally as they’re supplanted by more modern conveyances. Buddhadeb Bhattacharjee, after all, is not the first high West Bengal official to say that rickshaws would be off the streets of Kolkata in a matter of months. Similar statements have been made as far back as 1976. The ban decreed by Bhattacharjee has been delayed by a court case and by a widely held belief that some retraining or social security settlement ought to be offered to rickshaw drivers. It may also have been delayed by a quiet reluctance to give up something that has been part of the fabric of the city for more than a century. K olkata, a resident told me, “has difficulty letting go.” One day a city official handed me a report from the municipal government laying out options for how rickshaw pullers might be rehabilitated.“Which option has been chosen?” I asked, noting that the r eport was dated almost exactly a year before my visit.“That hasn’t been decided,” he said.“When will it be decided?”“That hasn’t been decided,” he said.11. According to the passage, rickshaws are used in Kolkata mainly for thefollowing EXCEPTA. taking foreign tourists around the city.B. providing transport to school children.C. carrying store supplies and purchasesD. carrying people over short distances.12. Which of the following statements best describes the rickshaw pullers fromBiharA. They come from a relatively poor area.B. They are provided with decent accommodation.C. Their living standards are very low in Kolkata.D. They are often caught by policemen in the streets.13. That “For someone without land or education, that still beats trying to make aliving in Bihar” (4 paragraph) means that even so,A. the poor prefer to work and live in Bihar.B. the poor from Bihar fare better than back home.C. the poor never try to make a living in Bihar.D. the poor never seem to resent their life in Kolkata.14. We can infer from the passage that some educated and politically aware peopleA. hold mixed feelings towards rickshaws.B. strongly support the ban on rickshaws.C. call for humanitarian actions fro rickshaw pullers.D. keep quiet on the issue of banning rickshaws.15. Which of the following statements conveys the author’s sense of humor?A. “…not the poor but people who are just a notch above the poor.”(2paragraph)B. “…,.which sounds like a pretty good deal until you’ve visited a dera.”(4paragraph)C. Kolkata, a resident told me, “ has difficulty letting go.” (7 paragraph).D.“…or, as I found during the 48 hours of rain, absolutely everything butumbrellas.” (6 paragraph)16. The dialogue between the author and the city official at the end of the passageseems to suggestA. the uncertainty of the court’s decision.B. the inefficiency of the municipal government.C. the difficulty of finding a good solution.D. the slowness in processing options.TEXT BDepending on whom you believe, the average American will, over a lifetime, wait in lines for two years (says National Public Radio) or five years (according to customer-loyalty experts).The crucial word is average, as wealthy Americans routinely avoid lines altogether. Once the most democratic of institutions, lines are rapidly becoming the exclusive province of suckers(people who still believe in and practice waiting in lines). Poor suckers, mostly.Airports resemble France before the Revolution: first-class passengers enjoy "élite" security lines and priority boarding, and disembark before the unwashed in coach, held at bay by a flight attendant, are allowed to foul the Jetway.At amusement parks, too, you can now buy your way out of line. This summer Ihaplessly watched kids use a $52 Gold Flash Pass to jump the lines at Six Flags New England, and similar systems are in use in most major American theme parks, from Universal Orlando to Walt Disney World, where the haves get to watch the have-mores breeze past on their way to their seats.Flash Pass teaches children a valuable lesson in real-world economics: that the rich are more important than you, especially when it comes to waiting. An NBA player once said to me, with a bemused chuckle of disbelief, that when playing in Canada--get this--"we have to wait in the same customs line as everybody else."Almost every line can be breached for a price. In several U.S. cities this summer, early arrivers among the early adopters waiting to buy iPhones offered to sell their spots in the lines. On Craigslist, prospective iPhone purchasers offered to pay "waiters" or "placeholders" to wait in line for them outside Apple stores.Inevitably, some semi-populist politicians have seen the value of sort-of waiting in lines with the ordinary people. This summer Philadelphia mayor John Street waited outside an AT&T store from 3:30 a.m. to 11:30 a.m. before a stand-in from his office literally stood in for the mayor while he conducted official business. And billionaire New York mayor Michael Bloomberg often waits for the subway with his fellow citizens, though he's first driven by motorcade past the stop nearest his house to a station 22 blocks away, where the wait, or at least the ride, is shorter.As early as elementary school, we're told that jumping the line is an unethical act, which is why so many U.S. lawmakers have framed the immigration debate as a kind of fundamental sin of the school lunch line. Alabama Senator Richard Shelby, to cite just one legislator, said amnesty would allow illegal immigrants "to cut in line ahead of millions of people."Nothing annoys a national lawmaker more than a person who will not wait in line, unless that line is in front of an elevator at the U.S. Capitol, where Senators and Representatives use private elevators, lest they have to queue with their constituents.But compromising the integrity of the line is not just antidemocratic, it's out-of-date. There was something about the orderly boarding of Noah's Ark, two by two, that seemed to restore not just civilization but civility during the Great Flood.How civil was your last flight? Southwest Airlines has first-come, first-served festival seating. But for $5 per flight, an unaffiliated company called will secure you a coveted "A" boarding pass when that airline opens for online check-in 24 hours before departure. Thus, the savvy traveler doesn't even wait in line when he or she is online.Some cultures are not renowned for lining up. Then again, some cultures are too adept at lining up: a citizen of the former Soviet Union would join a queue just so he could get to the head of that queue and see what everyone was queuing for.And then there is the U.S., where society seems to be cleaving into two groups: Very Important Persons, who don't wait, and Very Impatient Persons, who do--unhappily.For those of us in the latter group-- consigned to coach, bereft of Flash Pass, toopoor or proper to pay a placeholder --what do we do? We do what Vladimir and Estragon did in Waiting for Godot: "We wait. We are bored."17. What does the following sentence mean? “Once the most democratic ofinstitutions, lines are rapidly becoming the exclusive province of suckers…Poor suckers, mostly.” (2 paragraph)A. Lines are symbolic of America’s democracyB. Lines still give Americans equal opportunities.C. Lines are now for ordinary Americans only.D. Lines are for people with democratic spirit only.18. Which of the following is NOT cited as an example of breaching the line?A. Going through the customs at a Canadian airport.B. Using Gold Flash Passes in amusement parks.C. First-class passenger status at airports.D. Purchase of a place in a line from a placeholder.19. We can infer from the passage that politicians (including mayors andCongressmen)A. prefer to stand in lines with ordinary people.B. advocate the value of waiting in lines.C. believe in and practice waiting in lines.D. exploit waiting in lines for their own good.20. What is the tone of the passage?A. Instructive.B. Humorous.C. Serious.D. Teasing.TEXT CA bus took him to the West End, where, among the crazy coloured fountains of illumination, shattering the blue dusk with green and crimson fire, he found the caféof his choice, a tea-shop that had gone mad and turned. Bbylonian, a while palace with ten thousand lights. It towered above the other building like a citadel, which indeed it was, the outpost of a new age, perhaps a new civilization, perhaps a new barbarism; and behind the thin marble front were concrete and steel, just as behind the careless profusion of luxury were millions of pence, balanced to the last halfpenny. Somewhere in the background, hidden away, behind the ten thousand llights and acresof white napery and bewildering glittering rows of teapots, behind the thousand waitresses and cash-box girls and black-coated floor managers and temperamental long-haired violinists, behind the mounds of cauldrons of stewed steak, the vanloads of ices, were a few men who went to work juggling with fractions of a farming, who knew how many units of electricity it took to finish a steak-and-kidney pudding and how many minutes and seconds a waitress( five feet four in height and in average health) would need to carry a tray of given weight from the kitchen life to the table in the far corner. In short, there was a warm, sensuous, vulgar life flowering in the upper storeys, and a cold science working in the basement. Such as the gigantic tea-shop into which Turgis marched, in search not of mere refreshment but of all the enchantment of unfamiliar luxury. Perhaps he knew in his heart that men have conquered half the known world, looted whole kingdoms, and never arrived in such luxury. The place was built for him.It was built for a great many other people too, and, as usual, they were al there. It seemed with humanity. The marble entrance hall, piled dizzily with bonbons and cakes, was as crowded and bustling as a railway station. The gloom and grime of the streets, the raw air, all November, were at once left behind, forgotten: the atmosphere inside was golden, tropical, belonging to some high mid-summer of confectionery. Disdaining the lifts, Turgis, once more excited by the sight, sound, and smell of it all, climbed the wide staircase until he reached his favourite floor, whre an orchestra, led by a young Jewish violinist with wandering lustrous eyes and a passion for tremolo effects, acted as a magnet to a thousand girls, scented air, the sensuous clamour of the strings; and, as he stood hesitating a moment, half dazed, there came, bowing, s sleek grave man, older than he was and far more distinguished than he could ever hope to be, who murmured deferentially: “ For one, sir? This way, please,” Shyly, yet proudly, Turgis followed him.21. That “behind the thin marble front were concrete and steel” suggests thatA. modern realistic commercialism existed behind the luxurious appearance.B. there was a fundamental falseness in the style and the appeal of the café..C. the architect had made a sensible blend of old and new building materials.D. the café was based on physical foundations and real economic strength.22. The following words or phrases are somewhat critical of the tea-shop EXCEPTA. “…turned Babylonian”.B. “perhaps a new barbarism’.C. “acres of white napery”.D. “balanced to the last halfpenny”.23. In its context the statement that “ the place was built for him” means that the caféwas intended toA. please simple people in a simple way.B. exploit gullible people like him.C. satisfy a demand that already existed.D. provide relaxation for tired young men.24. Which of the following statements about the second paragraph is NOT true?A. The café appealed to most senses simultaneously.B. The café was both full of people and full of warmth.C. The inside of the café was contrasted with the weather outside.D. It stressed the commercial determination of the café owners.25. The following are comparisons made by the author in the second paragraphEXCEPT thatA. the entrance hall is compared to a railway station.B. the orchestra is compared to a magnet.C. Turgis welcomed the lift like a conquering soldier.D. the interior of the café is compared to warm countries.26. The author’s attitude to the café isA. fundamentally critical.B. slightly admiring.C. quite undecided.D. completely neutral.TEXT DI Now elsewhere in the world, Iceland may be spoken of, somewhat breathlessly, as western Europe’s last pristine wilderness. But the environmental awareness that is sweeping the world had bypassed the majority of Icelanders. Certainly they were connected to their land, the way one is complicatedly connected to, or encumbered by, family one can’t do anything about. But the truth is, once you’re off the beat-en paths of the low-lying coastal areas where everyone lives, the roads are few, and they’re all bad, so Iceland’s natural wonders have been out of reach and unknown even to its own inhab-itants. For them the land has always just been there, something that had to be dealt with and, if possible, exploited—the mind-set being one of land as commodity rather than land as, well, priceless art on the scale of the “Mona Lisa.”When the opportunity arose in 2003 for the national power company to enter into a 40-year contract with the American aluminum company Alcoa to supply hydroelectric power for a new smelter, those who had been dreaming of some-thing like this for decades jumped at it and never looked back. Iceland may at the moment be one of the world’s richest countries, with a 99 percent literacy rate and long lifeexpectancy. But the proj-ect’s advocates, some of them ge tting on in years, were more emotionally attuned to the country’s century upon century of want, hardship, and colonial servitude to Denmark, which officially had ended only in 1944 and whose psychological imprint remained relatively fresh. For the longest time, life here had meant little more than a sod hut, dark all winter, cold, no hope, children dying left and right, earthquakes, plagues, starvation, volcanoes erupting and destroying all vegeta-tion and livestock, all spirit—a world revolving almost entirely around the welfare of one’s sheep and, later, on how good the cod catch was. In the outlying regions, it still largely does.Ostensibly, the Alcoa project was intended to save one of these dying regions—the remote and sparsely populated east—where the way of life had steadily declined to a point of desperation and gloom. After fishing quotas were imposed in the early 1980s to protect fish stocks, many indi-vidual boat owners sold their allotments or gave them away, fishing rights ended up mostly in the hands of a few companies, and small fishermen were virtually wiped out. Technological advances drained away even more jobs previously done by human hands, and the people were seeing every-thing they had worked for all their lives turn up worthless and their children move away. With the old way of life doomed, aluminum projects like this one had come to be perceived, wisely or not, as a last chance. “Smelter or death.”The contract with Alcoa would infuse the re-gion with foreign capital, an estimated 400 jobs, and spin-off service industries. It also was a way for Iceland to develop expertise that potentially could be sold to the rest of the world; diversify an economy historically dependent on fish; and, in an appealing display of Icelandic can-do verve, perhaps even protect all of Iceland, once and for all, from the unpredictability of life itself.“We have to live,” Halldór Ásgrímsson said in his sad, sonorous voice. Halldór, a former prime minister and longtime member of parliament from the region, was a driving force behind the pro ject. “We have a right to live.27. According to the passage, most Icelanders view land as something ofA. environmental value.B. commercial value.C. potential value for tourism.D. great value for livelihood.28. What is Iceland’s old-aged advocates’ feeling towards the Alcoa project?A. Iceland is wealthy enough to reject the project.B. The project would lower life expectancy.C. The project would cause environmental problems.D. The project symbolizes and end to the colonial legacies.29. The disappearance of the old way of life was due to all the following EXCEPTA. fewer fishing companies.B. fewer jobs available.C. migration of young people.D. impostion of fishing quotas.30. The 4 paragraph in the passageA. sums up the main points of the passage.B. starts to discuss an entirely new point.C. elaborates on the last part of the 3 paragraph.D. continues to depict the bleak economic situation.PART III GENERAL KNOWLEDGE (10 MIN)There are ten multiple-choice questions in this section. Choose the best answer to each question. Mark your answers on ANSWER SHEET TWO.31. Which of the following statements in INCORRECT?A. The British constitution includes the Magna Carta of 1215.B. The British constitution includes Parliamentary acts.C. The British constitution includes decisions made by courts of law.D. The British constitution includes one single written constitution.32. The first city ever founded in Canada isA. Quebec.B. Vancouver.C. Toronto.D. Montreal.33. When did the Australian Federation officially come into being?A. 1770.B. 1788.C. 1900.D. 1901.34. The Emancipation Proclamation to end the slavery plantation system in theSouth of the U.S. was issued byA. Abraham Lincoln.B. Thomas Paine.C. George Washington.D. Thomas Jefferson.35. ________ is best known for the technique of dramatic monologue in his poems..A. Will BlakeB. W.B. YeatsC. Robert BrowningD. William Wordsworth36. The Financier is written byA. Mark Twain.B. Henry James.C. William Faulkner.D. Theodore Dreiser.37. In literature a story in verse or prose with a double meaning is defined asA. allegory.B. sonnet.C. blank verse.D. rhyme.38. ________ refers to the learning and development of a language.A. Language acquisitionB. Language comprehensionC. Language productionD. Language instruction39. The word “Motel”comes from “motor + hotel”. This is an example of________ in morphology.A. backformationB. conversionC. blendingD. acronym40. Language is t tool of communication. The symbol “Highway Closed”on ahighway servesA. an expressive function.B. an informative function.C. a performative function.D. a persuasive function.Part IV Proofreading & Error Correction (15 min) The passage contains TEN errors. Each indicated line contains a maximum of ONEerror. In each case, only ONE word is involved. You should proofread the passage andcorrect it in the following way:For a wrong word, underline the wrong word and write the correct one in theblank provided at the end of the line.For a missing word, mark the position of the missing word with a "∧" signand write the word you believe to be missing in the blankprovided at the end of the line.For a unnecessary word, cross the unnecessary word with a slash "/" and put theword in the blank provided at the end of the line. EXAMPLEWhen ∧art museum wants a new exhibit, it ╱never buys things in finished form and hangs them on the wall. When a natural history museum wants an exhibition, it must often build it.1________an2________ never3________ exhibitSo far as we can tell, all human languages are equally complete and perfectas instruments of communication: that is, every language appears to be well equipped as any other to say the things their speakers want to say.There may or may not be appropriate to talk about primitive peoples or cultures, but that is another matter. Certainly, not all groups of people are equally competent in nuclear physics or psychology or the cultivation of rice or the engraving of Benares brass. Whereas this is not the fault of their language. The Eskimos can speak about snow with a great deal more precision and subtlety than we can in English, but this is not because the Eskimo language 1 2 3(one of those sometimes miscalled 'primitive') is inherently more precise and subtle than English. This example does not come to light a defect in English, a show of unexpected 'primitiveness'. The position is simply and obviously that the Eskimos and the English live in similar environments. The English language will be just as rich in terms for similar kinds of snow, presumably, if the environments in which English was habitually used made such distinction as important.Similarly, we have no reason to doubt that the Eskimo language could be as precise and subtle on the subject of motor manufacture or cricket if these topics formed the part of the Eskimos' life. For obvious historical reasons, Englishmen in the nineteenth century could not talk about motorcars with the minute discrimination which is possible today: cars were not a part of their culture. But they had a host of terms for horse-drawn vehicles which send us, puzzled, to a historical dictionary when we are reading Scott or Dickens. How many of us could distinguish between a chaise, a landau, a victoria, a brougham, a coupe, a gig, a diligence, a whisky, a calash, a tilbury, a carriole, a phaeton, and a clarence ?4 5 6 7 8 910PART II READING COMPREHENSION11.A 12.C 13.B 14.A 15.D16.C 17.C 18.A 19.D 20.B21. A 22.B 23. B 24.B 25. C26.A 27.D 28.D 29.A 30.C31. Which of the following is INCORRECT答案D：The British Constituiton includes one single written constitution答题技巧：首先注意题干INCORRECT, 根据常识判断英国宪法为不成文宪法；故本题选择D，其他选项更为细节，直接忽略跳过。

枯草杆菌二联活菌颗粒和蒙脱石散不同服药方法治疗小儿轮状病毒肠炎的疗效比较

论著·临床论坛CHINESE COMMUNITY DOCTORS 中国社区医师2018年第34卷第29期轮状病毒肠炎属于急性消化道传染病，其会通过消化道传染，小儿的发病率较高，如果未及时接受治疗可能会出现电解质紊乱，脱水和肠道外多脏器受损的情况，并且小儿免疫力会有所降低，严重时会对其生命安全构成威胁[1]。

现阶段，临床上并无杀灭轮状病毒的特效药物，经常使用支持治疗，纠正水电解质、酸碱平衡和调整饮食的方法完成治疗，但经实践发现效果有待提升[2，3]。

2017年9月-2018年3月收治轮状病毒肠炎患儿46例，对枯草杆菌二联活菌颗粒与蒙脱石散不同服药方法治疗小儿轮状病毒肠炎的效果进行探讨，现总结如下[4]。

资料与方法2017年9月-2018年3月收治轮状病毒肠炎患儿46例，所有患儿均存在呕吐、水样大便和发热的情况，检查结果符合轮状病毒肠炎的诊断标准，且不存在其他严重性疾病，医院伦理委员会已经批准，且家属自愿签署知情同意书。

使用抽签法将患者分为试验组和对照组，各23例。

试验组男13例，女10例；年龄0.52～2.07岁，平均(1.30±0.54)岁；病程1.53～4.57d，平均(3.05±0.72)d。

对照组男12例，女11例；年龄0.53～2.10岁，平均(1.32±0.55)岁；病程1.54～4.59d，平均(3.07±0.76)d。

两组患儿在年龄、性别与病程上比较差异无统计学意义(P ＞0.05)。

方法：对照组患儿使用常规方法进行治疗，枯草杆菌二联活菌颗粒和蒙脱石散的服用时间可随意设定，剂量为常规剂量。

其中枯草杆菌二联活菌颗粒的具体服用量：年龄＜1岁的患儿每天服用1g，年龄1～3岁的患儿每天服用2g，均分2次服用。

蒙脱石散具体服用量：年龄＜1岁的患儿每天服用3g，年龄1～3岁的患儿每天服用2～5g，均分3次服用。

试验组患儿首先服用枯草杆菌二联活菌颗粒，服用1h 后再服用蒙脱石散，2h 后进食，服用剂量为对照组的2倍，如患儿存在脱水的症状需让其口服补液盐，如患儿发热、呕吐和脱水情况比较严重时需静脉滴注利巴韦林，避免出现不良情况。

PRODUCTION OF SPHERE OF SUBLIMABLE SUBSTANCE

专利名称：PRODUCTION OF SPHERE OF SUBLIMABLE SUBSTANCE发明人：KIDA KOJI,ITAKURA KOHEI,MIHASHISHIGEO申请号：JP14814988申请日：19880617公开号：JPH0415161B2公开日：19920317专利内容由知识产权出版社提供摘要：PURPOSE:To obtain spheres of a sublimable substance hardly causing caking by melting the substance and bringing droplets of the molten substance into contact with an atmosphere of mist of an inert liq. having a lower b.p. than the m.p. of the sublimable substance and not dissolving the substance to cool and solidity the droplets. CONSTITUTION:A sublimable substance such as iodine is melted in a melting pot 6 placed above the body 1 of an apparatus and the molten substance is dispersed and dropped as droplets of 0.3-5mm diameter into the central upper part of the body 1 from a dropping nozzle 2 through a duct 7. A nozzle 3 for spraying a coolant is fixed in the side wall of the body 1 in the horizontal direction at a position at which the dropped molten sublimable substance becomes discontinuous droplets. A feed pipe 8 is connected to a pressure pump 9 and a coolant such as water or alcohol is fed to the nozzle 3 and sprayed on the droplets to cool and solidify the droplets.申请人：ISE CHEM IND更多信息请下载全文后查看。

Production and Application of Protozoa Cultures of

专利名称：Production and Application of Protozoa Cultures of Histomonas Meleagridis (H.Meleagridis)发明人：Michael Hess,Petra Ganas申请号：US14412582申请日：20130702公开号：US20150157698A1公开日：20150611专利内容由知识产权出版社提供摘要：The invention discloses a method for producing a single bacterial strain culture of (), the method being characterised by the following steps: (a) providing a xenic culture of comprising cells with a wild type bacterial flora, (b) treating the xenic culture with a mixture of antibiotics thereby killing the wild type bacterial flora, (c) centrifuging and washing the cells, (d) controlling effectiveness of step (b), (e) resuspending the washed cells, (f) adding one or more single bacterial strain (s) to the resuspended cells, and (g) culturing the one or more single bacterial strain (s) with the resuspended cells so as to obtain a single bacterial strain culture of . The invention further discloses a vaccine formulation consisting of a component consisting of an attenuated culture of , a bacterial component consisting of one or more cultures of a single bacterial strain, and pharmaceutically acceptable non-biological formulation compounds.申请人：VETERINARMEDIZINISCHE UNIVERSITAT WIEN地址：Vienna AT国籍：AT更多信息请下载全文后查看。

有机葡萄生产中病虫害防治方法综述

492020.5有机葡萄生产中病虫害防治方法综述宋双，姜彩鸽，王国珍，张怡*（宁夏农林科学院植物保护研究所，宁夏银川 750002）摘要：有机葡萄生产中不能使用任何的化学肥料、杀菌剂、杀虫剂、除草剂和类似的非天然制品，而是要选用生物菌剂、微生物农药等。

有机葡萄的生产旨在生产高质量的葡萄，同时最大限度地减少葡萄园的投入。

本文针对葡萄病虫害的主要发生种类，提出综合防治措施，包括做好植物检疫，采取农业防治、生物防治、物理防治和药剂防治等。

根本在于通过物理与机械防治以及合理的农业防治，并配合使用有机农药，在一定程度上有效控制病虫害的发生发展，确保葡萄的有机生产。

关键词：有机葡萄；病虫害；防治方法中图分类号：S663.1；S436.631 文献标志码：A DOI ：10.13414/ki.zwpp.2020.05.012Discussion on the control methods of diseases and insect pests oforganic grape productionSONG Shuang, JIANG Caige, WANG Guozhen, ZHANG Yi*(Institute of Plant Protection, Ningxia Academy of Agricultutal Science, Yinchuan 750002, China)Abstract : Chemical fertilizers, fungicides, pesticides, herbicides and similar non-natural products cannot beused in organic grape production. Instead, biological agents and microbial pesticides should be used. Organic grape production aims to gain high quality grapes while minimizing vineyard investment. Main species of diseases and insect pests and comprehensive preventive health measures in the production of organic grape were introduced. According to the main species of grape diseases and insect pests, this paper proposed comprehensive control measures, including phytosanitary measures, agricultural control, biological control, physical control and pharmaceutical control. It's all about passing through effectively controlling the occurrence and development of diseases and insect pests to a certain extent through physical and mechanical control and reasonable agricultural control, combined with the use of organic pesticides, ensuring organic production of grapes.Key words : organic grape; diseases and insect pests; control method收稿日期：2020-04-09基金项目：酿酒葡萄病虫害绿色防控技术研究（NKYZ-16-06-03）；国家现代农业产业技术体系专项资金（CARS-29）；宁夏“十三五”重大科技项目（2018BBF02021）；宁夏农林科学院科技创新先导资金项目-农业区非耕地除草技术研究（NKYG-18-07-02）作者简介：宋双（1987—），女，汉族，硕士，助理研究员，现主要从事葡萄病虫害研究。

陶瓷工艺视野下景德镇“非遗”传承现状

中国陶瓷工业CHINA CERAMIC INDUSTRY第28卷第2期Vol.28, No.2Apr. 20212021年4月DOI: 10.13958/ki.ztcg.2021.02.012陶瓷工艺视野下景德镇“非遗”传承现状林俊杰，桑月侠，吴军明，郑乃章，韩光大(景德镇陶瓷大学，江西景德镇333000)摘要：景德镇在千年制瓷的过程中，保留有数量众多的窑业遗存，是景德镇成为首批历史文化名城的重要物质和文化基础。

陶瓷“非遗”的保护工作是景德镇文化建设工作的重要方面。

手工制瓷技艺是景德镇非物质文化遗产保护工作最重要的对象。

其2006年入选第一批国家级非物质文化遗产名录。

此后省市级的“非遗”项目大多是以部分工艺环节作为立项内容，在这样的条件下发展而出的体系存在一些问题。

笔者系统梳理了现有景德镇非物质文化遗产项目、传承人状况以及之间的关系，得出了一些结论。

关键词：景德镇；“非遗”；陶瓷工艺中图分类号：TQ174.79 文献标志码：A 文章编号：1006-2874(2021)02-0053-05Inheritance Status of "Intangible Cultural Heritage" in Jingdezhen fromCeramic Technology PerspectiveLIN Junjie, SANG luexia, WU Junming, ZHENG Naizhang, HAN Guangda(Jingdezhen Ceramic Institute, Jingdezhen 333000, Jiangxi, China)Abstract: In the process of porcelain making for thousands of years, Jingdezhen has retained a large number of ware remains,which is an important material and cultural foundation for Jingdezhen to become the first batch of historical and cultural cities. The protection of ceramic "Intangible Cultural Heritage^ is an important aspect of Jingdezhen's cultural construction whilehand-made porcelain protection is the most important object. In 2006, it was selected as the first batch of national intangible cul tural heritage lists. Since then, most of the ^Intangible Cultural Heritage ” projects 砒 the provincial and municipal levels are basedon part of the ceramic technique process and thus the system developed under such conditions caused some problems. This papersystematically combed the existing Jingdezhen intangible cultural heritage items, the status of the inheritors and the relation ship between them, and reached some conclusions.Key words: Jingdezhen; ^Intangible Cultural Heritage ,s ; ceramic technology景德镇是世界瓷都，为国务院首批公布的24 座历史文化名城之一，陶瓷文化是其立身之本。

谈谈你对帕累托的理解英语作文

谈谈你对帕累托的理解英语作文Understanding Pareto's Principles.In the realm of economics and social sciences, Vilfredo Pareto's name is synonymous with a concept that has revolutionized the way we view resource allocation, wealth distribution, and decision-making. Known as the "80-20 Rule" or the "Pareto Principle," this idea suggests that in many situations, 80% of the effects come from 20% of the causes. While the exact percentages may vary, the principle holds that a minority of factors often account for the majority of outcomes.At its core, the Pareto Principle challenges the assumption of equal distribution and instead highlights the disproportionate impact of a few key variables. In economics, this can be observed in the distribution of wealth, where a small percentage of the population often controls a significant portion of the wealth. Similarly, in production processes, a small number of factors oftencontribute significantly to overall output.The principle also finds application in various fields beyond economics. In project management, for instance, it is often found that a few key tasks account for the majority of the project's value or risk. In marketing, a small fraction of products or services may generate the bulk of revenue. This understanding helps businesses prioritize their efforts and focus on the most profitable areas.The Pareto Principle also has implications for decision-making. It suggests that by identifying and addressing the most significant factors, one can achieve disproportionate returns on investment. For instance, in time management, recognizing that a small number of tasks contribute most to one's goals can help individuals prioritize their workload more effectively.However, it's important to note that the Pareto Principle is not a law of nature but an observation of patterns found in certain systems. It's not applicable inall scenarios, and its application can be controversial. For instance, some argue that focusing exclusively on the 20% may overlook important nuances and unintended consequences.Despite its limitations, the Pareto Principle remains a valuable tool for understanding and analyzing complex systems. It encourages a mindset of identifying and leveraging key levers for maximum impact. It challenges us to question the assumption of equality and instead consider the disproportionate role played by a few critical factors.In conclusion, the Pareto Principle offers a useful framework for understanding the asymmetric distribution of resources, wealth, and influence. It encourages a focus on the most significant factors and highlights the disproportionate impact they can have on overall outcomes. While it should not be applied blindly, the principle remains a valuable tool for analysis and decision-making in various fields.。

probable动词形式

probable动词形式1. 解答主题- 动词形式：probabilize（使……成为可能；使有希望）- 英语解释：To make something probable or likely.（使某事成为可能或有希望的。

）- 中文翻译：使可能化；使或然化2. 词干（词根）、前缀、后缀的使用情况- 词干（词根）：“probable”的词干是“prob -”，它来源于拉丁语“probare”，表示“测试、证明、认可”等意思，在“probable”中表示“可被认为是（这样的）”，也就是“可能的”。

在“probabilize”中，这个词干保留了其核心意义。

- 前缀和后缀：“probabilize”中，“ - ize”是一个常见的后缀，用于将形容词或名词转化为动词，表示“使……化”的意思。

这里没有使用前缀。

3. 不同词式造句及翻译- 一般现在时- 句子：The new technology probabilizes the wide application of renewable energy.（这项新技术使可再生能源的广泛应用成为可能。

）- 一般过去时- 句子：His discovery probabilized a new way of treating the disease last year.（他的发现去年使一种治疗这种疾病的新方法成为可能。

）- 现在进行时- 句子：The government is probabilizing the development of rural areas through various policies.（政府正在通过各种政策使农村地区的发展成为可能。

）- 将来时- 句子：The research project will probabilize a major breakthrough in this field.（这个研究项目将使该领域取得重大突破成为可能。

抗白血病药他米巴罗汀的合成工艺改进

第19卷　第4期2009年8月　总90期中国药物化学杂志C hinese Journal of M edicinal C hem istryV ol 119　N o 14　p.241A ug 12009Su m 90收稿日期:2008-12-10作者简介:肖健(1963-),男(汉族),福建三明人,高级工程师,主要从事药物化学教学与科研工作,Tel:(0591)83741121,E 2mail:xiaoj63@sina .com 。

文章编号:1005-0108(2009)04-0268-02抗白血病药他米巴罗汀的合成工艺改进肖健,罗兰,何舒澜(福建卫生职业技术学院药学系,福建福州350101)摘　要:目的改进抗白血病药他米巴罗汀的合成工艺。

方法以2,52二甲基22,52己二醇为起始原料,经傅克反应、水解、酰化、水解4步反应制得目标化合物他米巴罗汀。

结果与结论目标化合物的结构经I R 、1H 2NMR 、ESI 2MS 谱及元素分析确证,总收率为3818%,该合成路线反应步骤短,操作简便,成本低廉,有利于工业化生产。

关键词:他米巴罗汀;抗白血病;工艺改进中图分类号:R914 文献标志码:AI m proved syn thesis of an ti 2leuke m i a drug t am i baroteneX I AO J ian,LUO L an,H E Shu 2lan(D ep a rt m en t of Pha r m acy,Fujian H ea lth C o llege,Fuzhou 350101,C h ina )Abstract:A i m To i m p rove the synthetic p rocedure of tam ibarotene .M ethods Tam ibarotene w as synthesizedvia Friedel 2C rafts reaction,hydro lyzation,acylation and hydrolyzation from 2,52di m ethy l 22,52hexanedio l .Results and conclusi on The structu re of target com pound w as confor m ed by IR,1H 2NM R,ES I 2M S and ele 2m en tary analysis .The overall yield is 3818%.The i m p roved p rocess has the advantage of low cost and is suitab le fo r industrial p roduction .Key words:tam ibarotene;an ti 2leukem ia;p rocess i m p rovem ent 他米巴罗汀(tam ibarotene,1)化学名为42[(5,6,7,82四氢25,5,8,82四甲基222萘基)氨甲酰基]苯甲酸,商品名为Am nolake,属维甲酸类化合物,由日本新药株式会社(N ippon Shinyaku )开发,2005年6月13日在日本首次上市,适用于急性早幼粒细胞性白血病(A PL )复发或难治性白血病的治疗[1]。

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THE PRODUCTION OF PROBABILISTIC ENTROPYIN STRUCTURE/ACTION CONTINGENCY RELATIONS *Loet LeydesdorffDepartment of Science and Technology DynamicsNieuwe Achtergracht 1661018 WV AMSTERDAMThe NetherlandsDecember 1993AbstractLuhmann (1984) defined society as a communication system which is structurally coupled to, but not an aggregate of, human action systems. The communication system is then considered as self-organizing ("autopoietic"), as are human actors. Communication systems can be studied by usingShannon's (1948) mathematical theory of communication. The update of a network by action at one of the local nodes is then a well-known problem in artificial intelligence (Pearl 1988). By combining these various theories, a general algorithm for probabilistic structure/action contingency can be derived. The consequences of this contingency for each system, its consequences for their further histories, and the stabilization on eachside by counterbalancing mechanisms are discussed, in both mathematical and theoretical terms. An empirical example is elaborated.Keywords: social structure, communication, update, entropy, social action, conditionalizationTHE PRODUCTION OF PROBABILISTIC ENTROPYIN STRUCTURE/ACTION CONTINGENCY RELATIONSThe emphasis on "self-referentiality" and "autopoiesis" insociological theory enables us to use models from evolutionary biology for the analysis of social systems and their developments. Additionally, Luhmann (1984) proposed that society can be considered as constituted notof human beings, but of communications. This makes the study of social phenomena accessible for the mathematical modelling of communicationpatterns by means of Shannon's mathematical theory of communication (Shannon 1948). Luhmann (1984; 1990), however, elaborated this empirical perspective only with qualitative reference to evolution theory.Society as a system of communicationsOf course, communications are generated by human beings and have to be understood by human beings, but Luhmann's sociology defines society as the network which is added to the actors as the nodes. The network differs in nature and in operation from the individual systems: individual "consciousness systems" process thoughts on the basis of perceptions; while society processes communications. The two systems are coupled structurally, i.e., they presuppose each other in the operation, but the one is not an aggregate of the other. In addition to the four billion or so people who perform their own self-referential loops (e.g., "thinking"), society isalso a system. This system communicates with the actors at the nodes in terms of co-variances, while it exhibits auto-covariance in the remaining variance during any discrete time period. The social system is therefore2self-referential. (Whether self-referential social systems are also self-reproducing and reflexive, and therefore "autopoietic," remains another empirical question (cf. Teubner 1988; Leydesdorff 1993b).)In modern societies, communications are functionally differentiated. For example, one can communicate through market-transactions in the economy, or through love in personal relations. On the one hand, the focus on communications makes the theory of symbolic generalized communication media (cf. Parsons) the starting point for the development of the special sociologies (Luhmann 1982, 1988, and 1990). On the other hand, the reformulation of the unit of operation with reference to the communication system--instead of exclusive reference to the discrete actors--bridges the gap with symbolic interactionism as the other great tradition in American sociology (Luhmann 1975; Leydesdorff 1993c).When the system is functionally differentiated, the structural coupling between actors and the social communication system may take different forms in the various subsystems. However, these forms are functionally equivalent, and thus we may expect that the structure/action contingency relation can be studied in terms of one underlying general algorithm (cf. Giddens 1979; Burt 1982).The mathematical theory of communicationShannon (1948) deliberately chose to define information so that it would correspond with Boltzmann's (1877) definition of entropy in thermodynamics. In theoretical biology, evolutionary processes are increasingly studied in terms of non-equilibrium thermodynamics, i.e., as entropy generating processes (e.g., Brooks and Wiley 1986). Although Shannon's definitions have been controversial in the context of thermodynamics (e.g., Brillouin 1962; Wicken 1987), they have been less so when applied to social phenomena (e.g., Georgescu-Roegen 1971; Theil 1972;3Krippendorf 1986). The social sciences analyze variances: the variance of a distribution is expected to contain information which is part of the uncertainty in the system which exhibits the variation. This uncertainty can be considered as probabilistic entropy (cf. Bailey 1990).At the technical level, it is possible to develop a continuousversion of information theory using integral calculus (e.g., Shannon 1948; Theil 1978). However, for social phenomena the original, discrete version (which is also mathematically simpler) is more adequate, since actions are discrete instances. Measures of information theory in this discrete formare composed of sigmas, which allow for the systematic study of the processes of aggregation and disaggregation, and for the effects of groupings. Additionally, since the measures are non-parametrical and based only on probabilities (i.e., relative frequencies), neither the dimensionality of the problem nor the measurement scale is inhibitive (see also: Krippendorff 1986). Information theory can be developed in order to integrate static and dynamic forms of analysis (Theil 1972; Leydesdorff 1991).Let me now introduce the most important formulas.If we define h as the information content of the message that an event has occurred, then the expected information content of the distribution of a variable with relative frequency pican be written as:H = Σi pi* hi(1)By using Shannon's (1948) classical function for information(hi = 2log(1/pi)),i we may write:H = - Σipilog pi(2)4and for the multi-variate case:H = - Σi ΣjΣkpijklog pijk(3)As with chi-square, H can be used as a measure of the association among variables. The overall uncertainty for two variables x and y, H(x,y), is equal to H(y) plus the amount of uncertainty which x adds to it, given the uncertainty in y, i.e., H(x|y). (See Figure 1 from (Attnaeve 1959) for a visual representation.)Therefore:H(x,y) = H(y) + H(x|y) (4)The mutual information or transmission between x and y is consequently defined as:T(x,y) = H(x) - H(x|y) = H(y) - H(y|x) (5)This is the reduction in the uncertainty of the prediction of x, given knowledge about the distribution of y.While "delta chi-square" does not have a clear interpretation,ii the decomposition of H (and I, below) in terms of the contribution to the5uncertainty of each of the component cells (or subsets) isstraightforward.iii Additionally the following formula can be derived for the disaggregation of H into g groups (Theil, 1972):H = H 0 + Σg P g * H g (6)H 0 is a measure of the uncertainty among the groups g , or in other words, a measure of the specificity of the distribution of the relevant variables within the groups.On the basis of the above definition of information, it can be shown (see, e.g., Theil 1972) that if we have a system of mutually exclusive events, E i , with prior probabilities p i , then the expected informationcontent I of the message which transforms the prior probabilities p i intothe posterior probabilities q i is given by the following expression:I = Σi q i * log (q i / p i ) (7)Correspondingly, for the multi-variate case, the expected information content of the message transforming the prior probability distribution p ijk of events into the posterior probability distribution q ijk , is equal to:I = Σi Σj Σk q ijk * log (q ijk / p ijk ) (8)Although overall I >= 0,iv /\ I can become negative for a term if q < p .v(Of course, /\ H in formula (2) is always >= 0.) Furthermore, in the dynamic case the grouping rules among levels of aggregation are somewhat more complex than in the static case (cf. Theil 1972).However, in principle, the two formulas, i.e., for H and I , provide us with a complete framework for the development of a set of methodologies 6equivalent to multi-variate analysis and to time series analysis, respectively (Leydesdorff 1991).viThe structure/action contingency relationLetA be a structure andB a distribution of actors such that at each moment in time the actors will take action given this structure; thus, B is conditioned by A when it operates. Action which can thus be defined as B|A, has an impact on structure A only in instances thereafter. (See Figure 2for a visual representation.)1988; Leydesdorff 1993c): each actor is comparable to a local processor which acts on the basis of its own programme given the conditions set bythe network; while the operation of the network, which operates according7to its own programme, is conditioned by the sum total of the previous actions.Let us now describe these systems in information-theoretical terms. Structure A, which is expected to contain H(A) at time t conditions at that moment action(s) at B. Action can therefore be expected to contain only information. At the next moment (t + 1), structure A is informed by H(B|A)tthe message that action(s) at B has/have taken place, and therefore the. In a later section I system thereafter contains an uncertainty H(A|B)t+1decompose this a posteriori information content in the information contents of the a priori systems (A and B|A, respectively), but let me here first focus on the dynamics of the message that action has occurred.By using equation (7), we may write the information content of this message as follows:= Σq(A|B) * log{ q(A|B) / p(A)} (9) I(A|B : A)in which Σq(A|B) represents the a posteriori state of the structure (A), i.e., after action (B) has occurred, while p(A) describes the a priori probability distribution. In other words: this formula expresses the information content of the message that the structure has self-referentially to update its information content since actions at thenetwork nodes B have occurred.Since, according to the third law of the probability calculus:(10)p(A and B) = p(A) * p(B|A)(10')= p(B) * p(A|B)we may also write:8p(A) * p(B|A)p(A|B) = ───────────── (11)p(B)This is known as Bayes' Formula, and expresses the a posteriori probability as a function of the a priori ones. Indices for a priori (t) and aposteriori (t + 1) probabilities can be written as follows:p(A) * p(B|A)t tp(A|B)t+1= ───────────────── (11')p(B)tor equivalently, and using q as indicator of the a posteriori probability:q(A|B) * p(B)p(A) = ─────────────────── (12)p(B|A)Substituting (12) into (9) one obtains:I(A|Bt+1 : At) = Σq(A|B) * log{ p(B|A) / p(B)} (13)This formula can also be written as the difference between two logarithms:I(A|B : A)= Σq(A|B) * log{ q(A|B) / p(B)} +- Σq(A|B) * log{ q(A|B) / p(B|A)= I(A|B : B) - I(A|B : B|A)(14)9This difference is equal to an improvement of the prediction of the a posteriori structure: the expected information content of the message that A is conditioned by B (left-hand side of the equation) is equal to an improvement of the prediction of the a posteriori distribution (Σq(A|B))if one add to one's knowledge of the a priori distribution (Σp(B)) the information about how the latter distribution was conditioned by thenetwork distribution (Σp(B|A)).The crucial point is the implied shift in the systems of reference in formula (13). (This possibility is an analytical consequence of the dynamic, and therefore non-trivial interpretation of Bayes' Formula above.) The right-hand factor of the right-hand term, i.e., (Σp(B|A) / p(B)) in formula (13), describes the instantaneous conditioning of action bystructure at time t, while the left-hand factor refers to the descriptionof the network after action, i.e., Σq(A|B) at the next moment. Therefore, the formula explicates how action at the nodes and the network are conditioned mutually and dynamically.In other words: if one initially (at time t) had knowledge only ofthe distribution of the nodes, i.e., the actors (Σp(B)), and then became informed of how, at this moment, action at the nodes is distributed given the network (Σp(B|A)), formulas (9) and (13) teach us that this provides us with the same expected information (I) about the network distribution, given the nodes at t + 1 (i.e., the a posteriori distribution), as does the message that the network distribution is conditioned by the nodes. The improvement is equal to the prediction based on the a priori network. Thus, one can study the coupled systems from either side, but one learns only in terms of their interaction.10Interaction, conditionalization and the "freedom" of each system Let us first focus on the interpretation of the a priori system whichcan be described with Σp(B|A)/p(B)(in the right-hand factor of formula (13)).Obviously, this is a ratio; the denominator can be considered as a normalization term for the size of the action system in terms of the number of actors involved.viiiIf the actions are independent p(B) = ΣAp(B|A), and in this case:p(B|A)/p(B)= p(B|A)/ ΣAp(B|A)(15)In qualitative terms this normalization means that a structure A as a self-referential system can only incorporate information in terms which have been conditioned by itself, and which have been normalized. For example, in a democracy as a normative system, the independence of votes is assumed, and the system accepts a decision with 51% in favour, regardlessof whether the total number of voters in the system was a hundred or a million. Secondly, for example, a theoretical system like Newtonian mechanics cannot accept the upward motion of a plume as counter-evidence to the laws of gravity, since the only relevant action is to produce evidence which can be made available to it in its own theoretical terms. In the case of a theoretical system, this normalization obviously refers also to the statistics.Note that the normalization is symmetrical in A and B:p(B|A) / p(B)= {p(B|A)* p(A)} / {p(B)* p(A)} =11p(A and B) / p(A)* p(B)(16)What has been said of structure, is thus also true of action insofar as action is to be considered as a system. If actions, however, are not independent in a system of actions, equality (15) no longer holds.Actions can be coupled in a system (the actor), and this system can be "autopoietic" or not, dependent upon the form of the coupling. In other words: there are various ways in which actions can be aggregated. An action system is autopoietic if the actor is an individual who relates the actions internally. For example, if a scientist first must do research and onlythen can publish it, there is additional uncertainty created within his/her system since there are various ways in which the two acts can be related. Analogously, if there are (feedback) relations among actions by different actors in an organization (e.g., in a research community or a department), this system can have a more systematic impact on the relevant structures (e.g., the scientific communication system), since the assumption of independence among the actions is no longer valid. I return to the issue of the generation of uncertainty and redundancy by other actors in a later section.In summary, a self-referential structure does not merge with the uncertainty in the events within its environment, but only with the uncertainty which it has previously conditioned within its environment, and after normalization for the size of the events. In other words: structure and action exchange information only insofar as they are coupled, and only to the extent that the other system is performing above or below the apriori expectation.12However,howB is conditioned by A does not inform us about how A isconditioned by B, but only about their "mutual information," i.e., the extent to which the conditioning reduces the remaining uncertainty. Knowledge of this (static!) transmission between action and structure reduces the uncertainty in the transmission at the next moment. The remaining uncertainty in A (or B) remains always underdetermined (i.e., "free"): each system contains its own total uncertainty, on the basis of which it enters self-referential loops in which it conditions the actions which generate relevant information for it. After the cycle (a posteriori) the fact that a specific interaction with B has occurred belongs to the history of A (i.e., "is a given for A"). I shall show in a later section that this necessarily adds to the information content of A (i.e., by making history, A increases its probabilistic entropy). However, the system's uncertainty can increase only to the maximal amount of uncertainty it cancontain, which is equal to the logarithm of its elements (log nA).The freedom of the two systems with respect to each other can also be seen mathematically on the basis of another interpretation of the (abovenoted) quotient between p(B|A) and p(B). As noted the two factors refer to"actions" and "actors", respectively. The difference between the twofactors (p(B) - p(B|A)) corresponds with that part of the uncertainty in Bwhich is determined by A. At any moment, knowledge of the uncertainty in the network improves our prediction of the uncertainty at the nodes of thenetwork, but only for the part of the transmission, i.e., H(B) - H(B|A)( =T(AB)) (see also Figure 1). It informs us only about the static transmission at that moment, i.e., about the impact of the vertical arrow in Figure 2, which indicates the instantaneous conditioning of actors by structure (cf.13Giddens 1979). However, the other part of the uncertainty (H) remainsB|Aprecisely undetermined by this conditioning, since it is only conditioned.by it. Mutatis mutandis the same holds true for H(A|B)Apart from the question of whether the actions are independent (i.e., whether equation (15) holds), the general algorithm for action/structure contingency relations (equation (13)) is necessarily true. The operation of the action system (e.g., actors) generates new information for structure, but the information adds to that part of the uncertainty in structure which is determined by this action system, and not to the remaining uncertainty. Therefore, left alone, two coupled systems would increasingly co-determine each other. However, in a multi-actor system other actions can add information to structure meanwhile, and thereby change theconditionalization. The synchronization of the relevant actions bystructure leads to Markov chain transitions as a special case.In summary: action pre-sorts information for structure, while it is itself conditioned by structure. However, the total information content of structure is independent of action: each system remains "free" at each moment in time. The improvement in the prediction is based only on thelocal interaction. Furthermore, because of the sigma in the algorithm the improvements are additive, and can therefore also be decomposed into single actions or subgroups of actions.14Empirical exampleAs noted, the resulting improvement in the prediction of A at the later moment is analytically due to the mutual information between A and B at the earlier moment. It is an evaluation of how much our knowledge of this transmission at the earlier moment informs us about the conditioning at the later moment. If there is conditionality in the (static)probabilistic relations between A and B, there is necessarily also dynamic coupling.If the systems A and B are completely coupled in one operation, theI(A|B : A) is equal to I(B|A : B), since the relations are symmetrical in A and B.However, if each of two systems pursues its own respective operation, the effects of their boundedness by each other will be asymmetrical. Since Ican also be used as a measure of the quality of the prediction, theformulas allow us to develop a measure of whether (and to what extent) the one type of data in empirical research on structure/action contingencies represents structure, while the other represents action, or vice versa. One can also easily imagine designs in which what is action at one moment in time will operate as structure at a later moment. Methodologically the two perspectives provide symmetrical tests, just as they do conceptually in the idea of a "mutual shaping" of structure and action by one another.For an empirical illustration, let me use the transaction matrix of the aggregated citation data of 13 major chemistry journals among each other. These matrices can be easily compiled using the Journal Citation Reports of the Science Citation Index.ix I shall use the 1984 matrix for the15journals listed in Table 1 as the a priori distribution, and the 1985 one as the a posteriori distribution.In each year, the matrix contains a "being cited pattern" that can be taken as structure, and the "citing" side can be considered as action. By citing one another the journals reproduce structure in a subsequent year. Since the citation matrix contains information with respect to both the cited and the citing dimension, it should provide us with an opportunity to make predictions about this reproduction of structure.In 1984, we can compute the (static) transmission between the "cited" and the "citing" side of this matrix by using formula (5). The expected information content of this message is 964.17 mbits of information. For 1985, this mutual information is 972.48 mbits, i.e., 8.31 mbits more. However, in the dynamic model (i.e., by using formula (13)) we find an improvement in the prediction for 1985 to 969.73 mbits on the basis of 1984 data.x This means that 5.56 mbits of the 8.31 mbits change in the transmission (or 66.9%) can be attributed to the previous transmission. In other words: the increase in the coupling is above expectation. (One reason for this may be that there occurred, for example, a grouping among thecited into a structure or feedback among the citing journals.) Since the operations of "cited" and "citing" are mutual in this universe of 13 journals, this result remains the same when the matrix is transposed. The two systems are completely coupled, since there is only one operation, viz. citation. However, in the parallel and distributed computer model, one may also assume a communication system between the cited and the citing journals, in which the operations are mediated by the network, and thus in principle asymmetrical. In this case, one needs an independent16operationalization of structure in the communication system, e.g., in terms of the eigenstructure of the matrix. Note that the eigenstructure of an asymmetrical matrix is asymmetrical indeed.In order to keep the analysis simple, let us make the (reasonable)xi assumption that this set of 13 journals can be grouped in three sets, namely: one of inorganic chemistry journals, one of organic chemistry journals, and one of journals which belong to the specialties of physical chemistry and chemical physics. (The attribution of the journals to these groups is given in Table 1.) This provides us, in a second research design, with a matrix of three cited clusters which represent the cited structure, and 13 citing journals which represent action. At a third level, we maythen also group the citing journals, and analyze the three by three matrix which represents the interaction between the presumed cited and citing structures.As above, on the basis of the 1984 matrix we can make a prediction of the transmission in the 1985 matrix. In the case of the asymmetrical matrix of three cited journal groups versus 13 independent citing journals, the actual transmission is 726.75 mbits in 1984 and 732.23 mbits in 1985.xii The prediction on the basis of 1984, is 731.81 for 1985, i.e., the prediction now covers 92.3% of the 5.48 mbits increase in the transmission (as against 67.1% in the previous case).If we subsequently assume that the citing action is not independent but completely grouped into the same three groups as the cited structure, the transmission is 669.33 mbits in 1984, and 672.43 in 1985. Now the prediction on the basis of 1984 is 673.02 mbits, which is 19.0% more than the observed increase in the transmission in 1985. Obviously, the17assumption of complete grouping on both the cited and the citing side overestimates the structural coupling.xiiiIn summary: I have elaborated here only an elementary model as an example. It is crude, among other things, since I did not allow for more groupings than the one into three groups, and I assumed that the one-year difference was an adequate time-scale. However, within this model a fit larger than 0.92 is obtained if we assume that the cited side isstructured, and that on the citing side the journals behave independently.Consequences for the history of the coupled systemsThe improvement in the prediction by action (formula (13)) is necessarily positive, since it is equal to the message to the system that action has taken place (i.e., formula (9) above); and this latter formula can be shown to be necessarily positive (Theil 1972, pp. 59f). Therefore, the prediction of "structure given action" at the later stage is always improved if we know how structure conditioned action at the previous stage. In each cycle, there is an increase of expected information content, sincethe new (larger) value H(A|B) will be the initial value (H(A)) for the nextcycle. Therefore, a structure/action contingency produces probabilistic entropy, and thus makes possible a history.xivLet me focus here on what it means theoretically and formally to say that structure gains probabilistic entropy by action. Intuitively it means that structure becomes more uncertain by action. Action incessantly adds to the uncertainty which prevails in the network. One can reduce this uncertainty only by the introduction of redundancy. (I return to thislatter option in a later section.)18How does the generation of uncertainty work? Let us decompose the a posteriori information content into the a priori ones, and see what is added. After a given event, the total uncertainty in the structure can be written as follows:H(A|B)= - Σq(A|B)* log(q(A|B))By using Bayes' formula, we can evaluate this a posteriori result into its a priori components, as follows:p * p p * p(A)(B|A)(A)(B|A)H(A|B)= - Σ───────────── * log{ ───────────── }p(B)p(B)=-Σ [p(A) * {p(B|A)/ p(B)}] * [ log{p(A)} + log{p(B|A)/ p(B)}](See a previous section for the interpretation of {p(B|A) / pB} as an a priorisystem.)H(A|B) = - Σp(A)* log{p(A)} - Σ {p(B|A)/ p(B)} * log{p(B|A)/ p(B)} +- Σp(A)* log{p(B|A)/ p(B)} - Σ {p(B|A)/ p(B)} * log{p(A)}= H(A)+ H(B|A)/(B)+- Σp(A)* log{p(B|A)/ p(B)} - Σ {p(B|A)/ p(B)} * log{p(A)}= H(A)+ H(B|A)/(B)+- Σp(A)* log{q(A|B)/ p(A)}19。