Lecture 15-Weak interactions and band theory
Weak convergence of finite graphs, integrated density of states and a Cheeger type inequali
a rX iv:mat h /5962v2[mat h.CO]23M ay26Weak convergence of finite graphs,integrated density of states and a Cheeger type inequality G ´a bor Elek ∗Abstract.In [4]we proved that the limit of a weakly convergent sequence of finite graphs can be viewed as a graphing or a continuous field of infinite graphs.Thus one can associate a type II 1-von Neumann algebra to such graph sequences.We show that in this case the integrated density of states exists that is the weak limit of the spectra of the graph Laplacians of the finite graphs is the KNS-spectral measure of the graph Laplacian of the limit ing this limit technique we prove a Cheeger type inequality for finite graphs.AMS Subject Classifications:05C80,46L10Keywords:weak convergence of graphs,von Neumann algebras,isoperimetric inequalities,integrated density of states1Introduction1.1Weak convergence and limits of colored graph sequences First let us recall some of the definitions and the main result from[4].A rooted colored d-graph is afinite simple graph G with the following properties:•G has a distinguished vertex(the root).•For any p∈V(G),deg(p)≤d.•The edges of G are properly colored by the colors c1,c2,...,c d+1.That is for each vertex q∈V(G)the outgoing edges from q are colored differently.Note that by Vising’s theorem each graph with vertex degree bound d has such an edge-coloring.A rooted(r,d)-ball is a rooted colored d-graph such that sup y∈V(G)d G(x,y)≤r,where x is the root of G and d G denotes the shortest path distance.Two rooted colored d-graphs G and H are rooted isomorphic if there exists a graph isomorphism between them preserving the colors and mapping one root to the other one.We denote by C r,d thefinite set of rooted isomorphism classes of rooted(r,d)-balls.Now if G is a rooted colored d-graph and A∈C r,d,then T(G,A)denotes the set of vertices v in V(G)such that A represents the rooted isomorphism class of the r-neighborhood of v,B r(v).Set p G(A):=T(G,A)We call such a system G={X,T1,T2,...T d+1,µ}a d-graphing.A d-graphing determines an equivalence relation on the points of X.Simply,x∼G y if there exists a sequence of points{x1,x2,...,x m}⊂X such that•x1=x,x m=y•x i+1=T j(x i)for some1≤j≤d+1.Thus there exist natural simple(generally infinite)graph structures on the equivalence classes,the leafgraphs.Here x is adjacent to y,if x=y and T j(x)=y.By our conditions, all the leafgraphs have vertex degrees bounded by d and are naturally edge-colored(the (x,y)edge is colored by c j if T j(x)=y).Now if A∈C r,d,we denote by p G(A)theµ-measure of the points x in X such that the rooted r-neighborhood of x in A in its leafgraph is isomorphic to A as rooted(r,d)-ball.We say that G is the limit graphing of the weakly convergent sequence{G n}∞n=1,if for any r≥1and A∈C r,dlim n→∞p Gn(A)=p G(A).In[4]we proved the following result.Theorem1If{G n}∞n=1is a weakly convergent system offinite connected d-graphs as above, then there exists a d-graphing G such that for any r≥1and A∈C r,d,lim n→∞p Gn(A)= p G(A).1.2Cheeger type isoperimetric inequalitiesNow let us recall two basic Cheeger-type isoperimetric inequalities for graphs.Let G(V,E) be afinite connected graph.For afinite connected spanned subgraph A⊆G we denote by ∂A the set of vertices x in V(A)such that x∈V(A),but there exists y/∈V(A)that x and y are adjacent vertices.The Cheeger constant h(G)is defined ash(G):={inf |∂A|2}.The classical isoperimetric inequality can be formulated the following way:For anyǫ>0 and d∈N,there exists a real constant C(ǫ,d)>0such that if G is afinite connected3graph with vertex degree bound d andλ1(G)≤C(ǫ,d)then h(G)≤ǫ.Hereλ1(G)is the first non-zero Laplacian eigenvalue of G.Now let G(V,E)be an infinite connected graph with bounded vertex degrees.Then the isoperimetric constant of G is defined as follows.|∂A|i(G):={inf.|V(G)|For afinite,connected graph G,ǫ>0and k∈N we denote by H(G,ǫ,k)the set of vertices in G which can be covered by a connected spanned subgraph A such that|A|≤k and|∂A|.Also,we denote by m(G,ǫ,k)the cardinality of the|V(G)|maximal disjoint system of connected spanned subgraphs A in V(G)such that|A|≤k and|∂A|For any t>0,there exist k(t),n(t)∈N and s(t)>0such that if|V(G)|≥n(t)holds for afinite connected graph G with vertex degree bound d,and s(G,E(ǫ,d))≥t,then m(G,ǫ,k(t))≥s(t).The main idea is to associate a type II1-von Neumann algebra for a weakly convergent graph sequence and prove that the integrated density of states exists that is the spectra of the graph Laplacians of thefinite graphs converge weakly to the so-called KNS-spectrum of the graph Laplacian on the limit graphing.Note that in[8]Lovasz and Szegedy introduced the notion of weak convergence and the limit object for dense graph sequences.They used the limit technique to give a new proof of a theorem of Alon and Shapira in[9].An another application of the limit technique can be found in the paper of Aldous and Steele[1].2The KNS-measureFirst let us recall the classical definitions of measureablefields of Hilbert-spaces and opera-tors[3].Let Z be the standard Borel space with a probability measureµ.Let H=l2(N)be the complex separable infinite dimensional Hilbert-space with orthonormal basis{e i}∞i=1.A measurablefield of Hilbert-spaces is given by a sequence{f n}∞n=1⊂L2(Z,µ)such that ∞n=1 Z|f n(x)|2dµ(x)<∞.By the Beppo-Levi Theorem for almost every x∈Z: f x= ∞n=1f n(x)e n∈H.We denote the space of the measurablefields of Hilbert spaces by Z H x dµ(x),which is a Hilbert-space with respect to the pointwise inner product.Afield of bounded linear operators is a B(H)-valued function on Z such thatx→<A x(e i),e j>is a measurable function for all i,j and Ess sup x∈Z A x <∞.Such fields of operators form the von Neumann algebra Z B(H)dµ(x),with pointwise addition, multiplication and∗-operation.Note that Z A x dµ(x)∈ Z B(H)dµ(x)is invertible if and only if A−1x exists for almost every x∈Z and Ess sup x∈Z A−1x <∞.Now we introduce the notion of continuousfield of graphs associated to a d-graphing. Let G=(X,T1,T2,...,T d+1,µ)be a d-graphing of our Theorem1.For each r≥1,and A r∈C r,d we label the vertices of A r by natural numbers inductively,satisfying the following5conditions:•The root is labeled by1.•Any vertex has different labeling.•The labeling of A r is compatible with the labeling of A r−1.•If d G(x,y)<d G(x,z),then the label of y is smaller than the label of z.•If|A r|=k,then the labels of the vertices is exactly{1,2,...,k}.Therefore for each x∈X we associate an infinite graph with edge-coloring by c1,c2,...,c d+1 and an extra vertex labeling by the natural numbers.Of course this graph is isomorphic to the leafgraph of x and each vertex can also be viewed as an element of X.This is the continuousfield of infinite graphs associated to the graphing.The total vertex set of thisfield is R⊂X×X,(x,y)∈R if x∼y,the equivalence relation given by the graphing.The space R is equipped with the counting measureν,[5]hence using the vertex labels one can view L2(R,ν)as X l2(V(G x))dµ(x).The leafwise Laplacian operator X∆G x dµ(x)is a measurablefield of bounded operators on X l2(V(G x))dµ(x).Feldman and Moore[5]introduced an important subalgebra of the algebra of thefields of bounded operators in the case of graphings.We briefly review their construction.Consider the space of bounded measurable functionsκ:R→C with finite bandwidth,that is for some constant bκ>0depending only onκ:κ(x,y)=0if d G(x,y)>bκ.Here d G(x,y)denotes the shortest path-distance on the leaf-graph of x. One can associate a measurablefield of bounded operators toκthe following way.If f∈L2(R,ν),then:Tκ(f)(x,y)= z∼x f(x,z)κ(z,y).These operators all called random operators.The weak closure of such operators Tκin X B(l2(V(G x))dµ(x)is the Feldman-Moore algebra N R.The point is that N R possessesa trace.It is a von Neumann algebra of type II1.The trace of Tκis given byTr G(Tκ)= Xκ(x,x)dµ(x).6The leafwise Laplacian operator on G,∆G is clearly an element of N R,given by a bounded measurable function offinite bandwidth,where∆G(f)(x,y)=deg(y)f(x,y)−z,z is adjacent to yf(x,z).We shall denote the Laplacians on thefinite graphs G i by∆Gi.(Of course the Laplacian does not depend on the edge coloring.)Proposition2.1For any n≥1:lim i→∞Tr i(∆n Gi)|V(G i)|= A∈C n,d p G i(A)s n(A),where s n(A)is the value of s n at the root.On the other hand,Tr G(∆n G)= A∈C n,d p G(A)s n(A).Hence our proposition follows.n.7By the classical(finite dimensional)spectral theorem:l 0x n dλ∆G i(x)=Tr i(∆n Gi)2D(ǫ,d),where D(ǫ,d)is the constant in the isoperimetric in-equality for infinite graphs.Suppose that the theorem does not hold.Then there exists t>0with the following property:For any k,one can choose a sequence{G k n}∞n=1offinite graphs with vertex degrees bounded by d such that•|V(G k n)|→∞.•s(G k n,1•|V(H n)|→∞.•s(H n,1|L′|≤ǫsuch that the root is in L′,then lim n→∞p Hn(A r)=0.Consequently,if one consider the limit graphing G of Theorem1,then for each leafgraph G x,i(G x)≥ǫ.That is for each leafgraph the spectral gap of the Laplacian at the zero is greater than32D(ǫ,d).In other wordsSpec( X∆G x dµ(x))∩[0,12D(ǫ,d)]is at least t.This leads to a contradiction.[5]J.Feldman and C.C.Moore,Ergodic equivalence relations,cohomology,and vonNeumann algebras.II.Trans.Amer.Math.Soc.234(1977),no.2,325-359.[6]R.Grigorchuk and A.Zuk,The Ihara zeta function of infinite graphs,the KNSspectral measure and integrable maps.in Random walks and Geometry,Walter de Gruyter Gmbh.141-180.[7]D.Lenz,N.Peyerimhoff and I.Veselic,Groupoids,von Neu-mann algebras and the Integrated Density of States manuscript URL: /pdf/math-ph/0204030[8]L.Lov´a sz and B.Szegedy,The limits of dense graph sequences.manuscript,URL:/users/lovasz/limits.pdf[9]L.Lov´a sz and B.Szegedy,Graph limits and testing hereditary properties.manuscript,URL:/users/lovasz/heredit-test.pdf[10]J.P.Serre,R´e partition asymptotique des valeurs propres de l’op´e rateur de HeckeT p.J.Amer.Math.Soc.10(1997),no.1,75-102.[11]P.M.Soardi,Potential theory on infinite networks.Lecture Notes in Mathematics,1590Springer-Verlag,Berlin,199410。
大学物理-电磁学(英文授课)
大学物理-电磁学（英文授课）IntroductionElectromagnetism is a field of physics that concerns itself with the study of electromagnetic forces and fields. It is a branch of physics that focuses on the interaction between electrically charged particles, including charged particles at rest and moving charges. This course is designed to help students understand the basic principles of electromagnetism, including electric and magnetic fields, electromagnetic radiation, and electromagnetic waves.Electric FieldsElectric fields are created by electric charges, which are either positive or negative. The electric field is said to be the space surrounding a charged particle. If another charged particle is placed in the electric field, it will experience a force. The direction of the force depends on the charge of the particle and the direction of the electric field.Magnetic FieldsMagnetic fields are created by moving charges. A magnetic field is said to be the space surrounding a magnetic object. If a charged particle is placed in a magnetic field, it will move in a circular path. The direction of the circular path depends on the charge of the particle and the direction of the magnetic field. Electromagnetic FieldsAn electromagnetic field is created by the interaction of an electric field and a magnetic field. Electromagnetic fields have both electric and magnetic components, and they travel through space at the speed of light. Electromagnetic waves are a form of electromagnetic radiation that carries energy. Electromagnetic radiation includes radio waves, microwaves, infrared light, visible light, ultraviolet light, X-rays, and gamma rays.Maxwell's EquationsMaxwell's equations describe the behavior of electric and magnetic fields. They are a set of partial differential equations that relate the electric and magnetic fields to the electric charges and currents that are present. The equations describe how an electric field can produce a magnetic field, and a magnetic field can produce an electric field. They also describe how the electromagnetic fields propagate through space.Electromagnetic WavesElectromagnetic waves are waves of energy that are propagated through space by the interaction of electric and magnetic fields. Electromagnetic waves do not require any medium to propagate through. They can travel through a vacuum, which is why they are also known as vacuum waves.Electromagnetic waves are classified based on their frequency and wavelength. Radio waves have the lowest frequency, and gamma rays have the highest frequency. Radio waves have the longest wavelength, and gamma rays have the shortest wavelength.Applications of ElectromagnetismElectromagnetism has many practical applications in our daily lives. Some of the most common applications include electric motors, generators, transformers, telecommunication devices, medical imaging devices, and microwave ovens. Electromagnetism has also played a significant role in the development of modern technology, including computers, television, radio, and mobile phones.ConclusionElectromagnetism is a fascinating field of physics that has wide-ranging applications in our daily lives. This course provides students with a comprehensive understanding of electric and magnetic fields, electromagnetic radiation, and electromagnetic waves. By studying electromagnetism, students can gain a deeper appreciation for the fundamental principles that govern the behavior of the universe around us.Electromagnetism is one of the four fundamental forces of nature, along with gravity, strong nuclear force, and weak nuclear force. It is a field of physics with numerous applications in our modern society. Without the understanding of electromagnetism, we would not have the modern comforts that we have today, including electricity, the internet, cell phones, and many other devices.One of the most significant contributions of electromagnetism to modern society is the use of electric motors. Electric motors are devices that convert electrical energy into mechanical energy.They are used in a wide range of applications, from household appliances to transportation systems. The underlying principle of electric motors is electromagnetic induction, which is the process of inducing an electric current in a conductor by varying the magnetic field around it.Another important application of electromagnetism is in generators. Generators are devices that convert mechanical energy into electrical energy. They are often used in power plants to generate electricity that is distributed to homes and businesses. The principle of electromagnetic induction is also used in generators. When a conductor moves through a magnetic field, an electric current is induced in the conductor.Electromagnetism also plays a central role in the functioning of transformers. A transformer is a device that changes the voltage of an alternating current (AC) power supply. Transformers are used to step up or step down the voltage of an AC power supply. They are used in power grids to maintain a constant voltage throughout the grid. The principle used in transformers is electromagnetic induction, with the primary and secondary coils of wire interacting with the magnetic field to produce the desired voltage change. Telecommunication devices, including radios, televisions, and cell phones, also rely on the principles of electromagnetism. The radio waves used for communication are a form of electromagnetic radiation. Radio waves are used to transmit and receive signals between devices. The workings of these devices depend on the principles of electromagnetic induction and electromagnetic radiation.In addition to powering devices, electromagnetism is used in medical imaging devices. Magnetic resonance imaging (MRI) machines use magnetic fields and radio waves to produce images of the body's internal structures. The patient is placed in a powerful magnetic field, which causes the protons in their body to align with the field. A radio wave is then sent through the body, causing the protons to produce a signal. The signal is detected, and an image is produced based on the strength and location of the signal.Microwave ovens are another example of electromagnetism in action. These appliances use microwaves to cook food. Microwaves are a type of electromagnetic radiation with a frequency of around 2.4 GHz. The microwaves cause the water molecules in the food to vibrate rapidly, producing heat. This heats the food quickly and evenly, making it a popular method for cooking.The study of electromagnetism has also led to the development of modern technology. Computers, televisions, radios, and cell phones all rely on the principles of electromagnetism. The development of these technologies has revolutionized the way we live and communicate. The internet, for example, would not exist without the principles of electromagnetism.In conclusion, electromagnetism is a fascinating field of physics with numerous practical applications in our daily lives. It is the foundation of modern technology, and our society would not be the same without it. By studying electromagnetism, we can gain a deeper understanding of the world around us and appreciate thefundamental principles that govern our universe. As technology advances, we can expect even more exciting and innovative applications of electromagnetism in the years to come.。
Elements of Decision- Making
GAME THEORY:
KEY ELEMENTS
(Brandenburger and Nalebuff, 1995)
According to game theory there are five main elements of the game:
• Players – customers, suppliers, competitors, employees etc. • Added Value – what each player brings to the game • Rules – gives structure to the game • Strategies – moves used to shape the game and how it is perceived • Payoffs – political social and economic
• TV programming
• Airlines flying schedule
• Politics – Left vs Right
ONE STAGE GAMES
• Easiest game, 2 players, 1 stage such as the coordination game. • Nash equilibrium – each player is making an optimal choice given the
other player’s choice
• In one stage games the key to how co-ordination is achieved centres on whether decision-making is:
• simultaneous - lack of information makes co-ordination more difficult to attain
凝聚态物理导论00
From Complexity to Simplicity (continued) Each stage of reduction is marked by the appearance of quasistable particles which had been mistakenly identified as “elementary” particles. With each stage of reduction, the length scale drastically decreases, while the energy scale drastically increases (see Fig. 1).
(in Chinese),《凝聚态物理学新论》(上海科技出版社)
New systematics was thoroughly discussed and illustrated with various current topics in this field National Award of Science and Technology Progress, 1997, in China
Electromagnetic Force is Ubiquitous
the sole fundamental force responsible for various complicated phenomena in condensed matter physics
3. Historical Track of Scientific Development
A brief overview of condensed matter physics
• The Position of Condensed Matter Physics in Physics • From Solid State Physics to Condensed Matter Physics • The Theoretical Framework of Condensed Matter Physics
李政道诺贝尔领奖辞lee-lecture.pdf
The interactions (not including the gravitational forces) between these par-ticles can be classified into three distinct groups:1. Strong Interactions. This group is responsible for the production and thescattering of nucleons, pions, hyperons (i.e. etc.) and K mesons. It ischaracterized by a couplinggC> = (1/137).3.Weak Interactions. This group includes all known non-electromagnetic de-cay interactions of these elementary particles and the recently observed ab-sorption process of neutrinoes by nucleons2.These interactions are charac-terized by coupling constants1957 T.D.L E EFig. 2.YThe law of conservation of parity is valid for both the strong and the elec-tromagnetic interactions but is not valid for the weak interactions. Today’s discussions will be mainly on the recently observed effects of nonconserva-tion of parity in the various weak interactions.IIThe weak interactions cover a large variety of reactions. At present there are about 20 known phenomenologically independent reactions ranging from the decay of various hyperons to the decay of light particles. Within the last year, many critical experiments have been performed to test the validity of the law of conservation of parity in these reactions. We shall first summarize the experimental results together with their direct theoretical implications.Next, we shall discuss some further possible consequences and theoretical considerations.W E A K I N T E R A C T I O N S A N D P A R I T Y M i r r o r r e f l e c t i o n409Fig. 3.(1)emitted, differentiates in a mostdirect way a right-handed system from a left-handed system. Thus the non-conservation of parity or the non-invariance under a mirror reflection can be established without reference to any theory.Furthermore from the large amount of angular asymmetry observed itcan also be established 4that the (1)in which each particle is described by a quantized wave equation. In partic-ular the neutrino is described by the Dirac equation6are the four (4 × 4)anti-commuting Dirac matrices and= ict are the four space-time coordinates. For each given mo-mentum there exists two spin states for the neutrino and two spin states for the anti-neutrino. These may be denoted by If we define thehelicity H to bewith the unit vector along the momentum direc-tion, then these four states have, respectively, helicities equal to + I, - I, -I and + I (Fig. 4). M a thand a left-handed part=(6)andIt is easy to see that both separately satisfy the Dirac equationt s ecomposition the β process of a nucleus A can be rep-[Eq. (2)]. With hi dresented schematically asFig. 4.and and+(7’)(8’)with as the corresponding amplitudes for emission ofUnder the charge conjugation operator we change a particle to its anti-particle but we do not change its spatial or spin wave functions. Conse-quently it must have the same helicity. Thus, if the β-decay process is in-variant under the charge conjugation operator, then we should expect pro-cess (7) to proceed with the same amplitude as process (8’). The condition for invariance under charge conjugation is, thenz (9)for all i = S, T, V, P, A.In the decay of 60Co, because there is a difference of spin values between 6O Co and 60Ni, only the terms i = T and i = A contribute. From the large angular-asymmetry observed it can be safely concluded that for bot h i = T, Awhich contradicts Eq. (9)and proves the non-invariance of β-interaction under charge conjugation. For illustration purposes, we assume in the abovethe neutrino to be described by a 4-component theory and further we assume that in the412 1957T.D.L E ERecently many more experiments7 have been performed on the longi-tudinal polarization of electrons and positrons, th e β−γ, correlation together with the circular polarization of the γ radiation and the β angular distribu-tion with various polarized nuclei other than 60Co. The results of all these experiments confirm the main conclusions of the first 60Co experiment, that both the parity operator and the charge conjugation operator are not con-served in β-decay processes.Another interesting question is whether the β-decay interaction is invariant under the product operation of (charge conjugation x mirror reflection). Under such an operation we should compare the decay of A with that ofa n dd e c a yThe π± meson decays into a µ± meson and a neutrino. The µ± meson, in turn, decays into an e± and two neutrinoes (or anti-neutrinoes). If parity is not conserved in π-decay, the µ meson emitted could be longitudinally po-Fig. 5.WEAK INTERACTIONS AND PARITY413 larized. If in the subsequentmeson (Fig. 5). Consequently in themeson measured in the rest system of measured in the restsystem ofThe experimental results8 on these angular correlations appeared within a few days after the results onLater, direct measurements9 on the longitudinal polarization of the posi-tron fromdecayIn this case we have instead of themeson and a neutrino (Fig. 6). Experiment10 on the angular correlation between theestablishes that in K-decay the par-ity as well as the charge conjugation operator is not conserved.(4)on proton. TheFig. 6.subsequently decays into a proton plus aπ− (Fig. 7). The observation of an a symmetrical distribution with respect to the sign of the product(Ginx the mo-mentum of the lambda particle,,,,,and that of the decay pionandFurthermore, from the amount of the large up-down asymmetry it can be concluded that the Λο-decay interaction is also not invariant under the charge conjugation operation.From all these results it appears that the property of nonconservation of parity in the variou s weak interactions and the noninvariance property of these interactions under charge conjugation are well established. In connec-tion with these properties we find an entirely new and rich domain of nat-ural phenomena which, in turn, gives us new tools to probe further into the structure of our physical world. These interactions offer us natural ways to polarize and to analyze the spins of various elementary particles. Thus, for example, the magnetic moment of the µ meson can now be measured to an extremely high degree of accuracy12which, otherwise, would be unattain-W E A K I N T E R A C T I O N S A N D P A R I T Y415 able; the spins of some hyperons now may perhaps be determined13 un-ambiguously through the observed angular asymmetries in their decays; new aspects of the electromagnetic fields of various gas, liquid and solid materials can now be studied by using these unstable, polarized particles. However, perhaps the most significant consequences are the opening of new possibil-ities and the re-examination of our old concepts concerning the structure of elementary particles. We shall next discuss two such considerations - the two-component theory of neutrino, and the possible existence of a law of con-servation of leptons.IIIBefore the recent developments on nonconservation of parity, it was cus-tomary to describe the neutrino by a four-component theory in which, as we mentioned before, to each definite momentum there are the two spin states of the neutrino plus the two spin states of the antineutrinoIn the two-component theory, however, we assume two of thesestates, say, simply do not exist in nature. The spin of the neutrinois then always parallel to its momentum while the spin of the antineutrino is always antiparallel to its momentum. Thus in the two-component theory we have only half of the degrees of freedom as in the four-component the-ory. Graphically we may represent the spin and the velocity of the neutrino by the spiral motion of a right-handed screw and that of the antineutrino by the motion of a left-handed screw (Fig. 8).The possibility of a two-component relativistic theory of a spin ½ particle was first discussed by H. Weyl14 as early as 1929. However, in the past, be-cause parity is not manifestly conserved in the Weyl formalism, it was always rejected15.With the recent discoveries such an objection becomes com-pletely invalid16.To appreciate the simplicity of this two-component theory in the present situation it is best if we assume further the existence of a conservation law for leptons17. This law is in close analogy with the corresponding conserva-tion law for the heavy particles. We assign to each lepton a leptonic num-ber l equal to +1or -1and to any other particle the leptonic number zero. The leptonic number for a lepton must be the negative of that for its antiparticle. The law of conservation of leptons then states that « in all physical processes the algebraic sum of leptonic numbers must be con-served ».W E A K I N T E R A C T I O N S A N D P A R I T Y417 two-component theory we have to investigate in detail all the neutrino pro-cesses. For example inor4181957T.D.L E E1. C. N. Yang, Nobel Lecture, this volume, p. 393.2. C. L. Cowan, Jr., F. Rines, F. B. Harrison, H. W. Kruse, and A. D. McGuire,Science, 124 (1956) 103.3. C. S. Wu, E. Ambler, R. W. Hayward, D. D. Hoppes, and R. P. Hudson,Phys.Rev., 105 (1957) 1413.4. T. D. Lee, R. Oehme, and C. N. Yang, Phys. Rev., 106 (1957) 340; B. L. Ioffe, L.B. Okun, and A. P. Rudik, J.E.T.P. (U.S.S.R.), 32 (1957) 396.5. We remark here that if the neutrino is described by a two-component theory (seeSection III) then the result of the large angular asymmetry in60Co decay estab-lishes in a trivial way the non-Invariance property of β-decay under the charge conjugation operation. However, this non-invariance property can also be provedunder a much wider framework. In this section we take as an example the case ofa four-component theory of neutrino to illustrate such a proof6.For notations and definitions of γmatrices see, e.g., W. Pauli,Handbuch der Physik,Julius Springer Verlag, Berlin, 1933, Vol. 24.7. For a summary of these experiments see, e.g., Proceedings of the Seventh AnnualRochester Conference,Interscience, New York, 1957.8. R. L. Garwin, L. M. Lederman, and M. Weinrich,Phys. Rev., 105 (1957) 1415;J. I. Friedman and V. L. Telegdi,Phys. Rev., 105 (1957) 1681.9. G. Culligan, S. G. F. Frank, J. R. Holt, J. C. Kluyver, and T. Massam, Nature, 180(1957) 751.10. C. A. Coombes, B. Cork, W. Galbraith, G. R. Lambertson, and W. A. Wenzel,Phys. Rev., 108 (1957) 1348.11. J. Crawford, et. al., Phys. Rev., 108 (1957) 1102; F. Eisler et al.,Phys. Rev., 108(1957) 1353; R. Adair and L. Leipuner, Phys. Rev., (to be published).12. T. Coffin, R. L. Garwin, L. M. Lederman, S. Penman, and A. M. Sachs, Phys.Rev., 107 (1957) 1108.13. T. D. Lee and C. N. Yang, Phys. Rev., 109 (1958) 1755.14. H. Weyl, Z. Physik, 56 (1929) 330.15. Cf. W. Pauli, Handbuch der Physik, Julius Springer Verlag, Berlin, 1933, Vol. 24,pp. 226-227.16. The possible use of a two-component theory for expressing the nonconservationproperty of parity in neutrino processes was independently proposed and dis-cussed by T. D. Lee and C. N. Yang, Phys. Rev., 105 (1957) 1671; A. Salam, Nuovo Cimento, 5 (1957) 299; and L. Landau,Nucl. Phys., 3 (1957)127.17. The possible existence of a conservation law for leptons has been discussed beforethe discovery of nonconservation of parity. Cf. E. Konopinski and H. M. Mah-moud, Phys. Rev., 92 (1953) 1045.。
译林版高中英语选择性必修第四册 Unit 2 Section A
D.make your communication more effective
答案 C
C.阅读P16—17课文,厘清文章结构。 how
exchange
value
competent attitudes
interactions
课堂篇 互动探究
重点词汇
1If you heard someone shout “Hey you!” from across the room,how would you react? 如果你听到有人从房间的另一边喊“嘿,你!”,你会有什么反应?(教材P16) ◆ react vi.(对……)作出反应;有不良反应,过敏;起化学反应 When you share a story with your friends,you care a lot more about how they react. 当你与朋友分享故事时,你会更加在意他们是如何反应的。 Primitive humans needed to be able to react like this to escape from dangerous animals. 原始人类需要能够像这样反应以逃脱危险动物。 Please think about what I’m writing and try hard not to react with anger. 请考虑我所写的内容,尽量不要反应过激。
Learning to read others’ positive body language cues is a useful skill,but don’t forget you can also use these cues yourself to reinforce⑥ your own words and create a positive impression.
Weak Interactions of Light Flavours
LSM = LH (φ) + LG (W, Z, G) + Higgs Gauge ¯ / ψ+ ψiD
ψ=fermions ψ,ψ′ =fermions
The Standard Model Lagrangian has four parts: ¯ ′ gψψ′ ψφψ Yukawa
QCD and QED conserve C,P,T separately. Local Field theory by itself implies CPT. The fermion and Higgs2 part of the SM-lagrangian conserves CP and T as well. The only part that violates CP and as a consequence also T is the Yukawa part. The Higgs part is responsible for two parameters, the gauge part for three and the HiggsFermion part contains in principle 27 complex parameters, neglecting Yukawa couplings to neutrinos. Luckily most of the 54 real parameters in the Yukawa sector are unobservable. After diagonalizing the lepton sector there only the three charged lepton masses remain. The quark sector can be similarly diagonalized leading to 6 quark masses, but some parts remain in the difference between weak interaction eigenstates and mass-eigenstates. The latter is conventionally put in the couplings of the charged W -boson, which is given by Vud Vus Vub dα g α − uα cα t γ µ (1 − γ5 ) Vcd Vcs Vcb sα − √ Wµ 2 2 V V V b
第一章 原子核的基本性质
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（3）重要的常量
• 阿伏伽德罗常数——联系了宏观与微观 › NA=6.02214199×1023/mol • 普朗克常量——能量、角动量的量子化，不确定度关系 › h = 6.62606876×10-34J· s = 4.13566727×10-22MeV· s › ħ =1.054571596×10-34J· s = 6.58211889×10-22MeV· s • 真空中的光速——越微观，越高速，必须考虑相对论效应 › c =2.99792458×108m/s • 基本电荷——质子、电子、原子核的电荷量 › e =1.602176462×10-19C • 真空中介电常数 › ε0 =8.854187817×10-12F/m
• 粒子性：particles of light
– 1900：Planck，黑体辐射 – 1905：Einstein，光电效应
– de Broglie 1924年提出实物（静质量非0）粒子也具有波 粒二象性。
de Broglie wavelength:
h p
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物质波的实验证实
C60分子的 干涉图像
有关核物理的理论与实验工作对20世纪的物理学发展起到了重要的作用。 核物理所涉及技术的应用范围和影响，超过了其它任何学科。
……. No other field of science comes readily to mind in which theory encompasses so broad a spectrum, from the most microscopic to the cosmic, nor is there another field in which direct application of basic research contain the potential for the ultimate limits of good and evil. K. S. Krane, Introductory Nuclear Physics, P.2
学术英语理工Abstract
Text 1Computer vulnerabilities are often utilized by hackers or crackers. The security of each computer i s challenging. This paper firstly redefines the term “hacker”, “cracker” and “getting inside ” the computers and describes the procedure in detail. The term “unauthorized user” (UU) will be a better choice for defining the insider group. The known and unknown vulnerabilities will be t aken advantage of by UUs ranging from poor password protection to leaving a computer turned on and physically accessible to visitors in the office. The first step of employing technical exploits wi ll be the determination of the specifications of the target system. There are two ways of attacking i ncluding being through capabilities inherent in hypertext transfer protocol and being preprogram med against specific vulnerabilities and launched without any specific target. The variability of ha cking action including the weak system and the strong system warns the users to choose the right way to protect the computer and do not authorize the computer to others easily. Lastly, the solution of avoiding vulnerabilities has been given, including updating patches, making complex password s, getting information only from the reliable websites or services, updating antivirus software and backing up the data to protect the computer not being hacked.Text 3Cloud of computing is allowing you to use services that include infrastructure applications ,and storage space for a nominal fee. It should be able to quickly allot and relieve resou rces whenever required by clients and cater to the needs of clients without having to invo lve clients into management of the service and have real- time backup to offer maximum up time clients. The type of cloud services includes software as a service ,platform as a s ervice ,infrastructure as a service .The advantages of cloud computing under green computi ng include reducing the consumption of electricity while also reducing emissions that dam age the environment ,saving the environment while also saving on the expenses incurred d ue to a demand for expansion ,and allowing you to let you employees telecommute. Then ,here is a summary about the advantages of cloud computing: remote accessibility , easy expansion ,security and environmentally friendly.Text 4Today, “Cloud Computing”has became a popular word. This paper focuses on security benefits of cloud computing. The future of the Internet belongs to the web 3.0, also called the intelligent web which can be seen as a new way of creating and using applications that can run on different devices and having the data stored into the cloud. The cloud means the Internet, and the current cloud computing architecture involves the existence of data centers that are able to provide services to the clients located all over the world. The cloud clients could be regular PCs, mobile phones, PDAs or any other similar devices. Cloud computing allows to move the processing effort from the local devices to the data center facilities. In these conditions, the security of data and applications becomes a very a major issue. The cloud computing has lots of advantages, of course there are some disadvantages. And the cloud computing provides some major security benefits for individuals or companies. Such as centralized data storage monitoring of data access become easier and so on. Cloud computing is still at the beginning. So the list remains wide open for newentries. Today, the information infrastructure is moving faster to a simple but very innovative concept called cloud computing. Many devices are cloud compatible in this context. Cloud computing is potentially able to offer major security benefits.Text 5With the development of social and technology, Artificial intelligence may replace human jobs in the future. There are a lot of news that reported artificial intelligence has play a important role in our life. For decades. People wrote about how machines replace humans. It will be better or ill. But all expected did not come. Around the time of the Revolution. Most of Americans worked in the farm. They farmed to keep themselves alive. With the development of traffic. Farming increasingly became a cash business. But as the agricultural industry grew, there are fewer and fewer workers who worked at farming and ranching. Today agricultural provides fewer than two million jobs. Because of automation happened. It bring better plows, planting and sowing machines. Agricultural become more and more scientific. The farmers’ children found new kinds of jobs in the city, they do not like stay on the farm. The early water-and-steam-powered factories also displace millions of craftsmen, because machine-handing factory workers made the goods better than the goods made by craftsmen. So that the number of factory jobs growing rapidly at that time. The automation of farming, craft work and manufacturing made products. Among them, food become cheaper and cheaper, so people can save money from food, then spend money on other expensive goods. Will A.I. machines take over the best occupations? The author is optimist and may not agree that machines will replace human jobs.Text 6Game theory Game theory is the science of strategy and was pioneered by Princeton mathematician John V on Neumann. In the early years the emphasis was on games of pure conflict. Other games were considered in a cooperative form. Games are different from decisions made in a neutral environment. The essence of a game is the interdependence of player strategies. There are two distinct typesof strategic interdependence:sequential and simultaneous. The logical circle is squared using a concept of equilibrium developed by the Princeton mathemat cian John Nash. Nash’s notion of equilibrium remains an incomplete solution to the problem of circular reasoning in simultaneous-move games. Some games have many such equilibrium while others have none. And this notion has some flaws. In spite of it,the concept has proved extremely useful in analyzing many strategic interactions. There are some examples of strategic interaction illustrate some of the fundmentals of game the ry:the prisoners’dilemma,mixing moves and strategic moves. Recent advances in game theory have succeeded in describing and prescribing appropriate strategies in several situations of conflict and cooperation. But the theory is far away from complete,and in many ways the design of successful strategy remains an art.Text 8At the begin of this article ,it states that there are unprecedented multidisciplinary convergence scientists dedicated to the study of a world so small that we can’t see it—even with a light microscope and tells us the important of nanotechnology .Then in order to understand the unusual world ofnanotechnology ,we need to get an idea of the units of measure involved .The long of one nanometer is so small .When we measure the atomic scale ,we can find that it’s still small compare to the nannmeter ,But in a lecture called “Small Wonders :The World of Nanoscience ”,Nobel Prize winner Dr .Horst Stormer said that the nanoscale is more interstesting than the atomic scale because the nanoscale is the first point where we can assemble something—it’s not until we start putting atoms together that we can make anything useful .Then the article states that some predictions of nanotechnology such as the use of the rule of quantum mechanics ,nanorobot .It states that there great value in nanotechnology in future.Text 9Global warming has been a global issue for many years now.However, the most prominent effect of global warming exists in the climate change over the past years. It causes the oceans warmer, the intensity of hurricanes amplifies in power and devastation. Another area affected by global warming is the animal kingdom and nature.The number of animals has been decreasing and the various disease has spread to new regions across the globe. A third type of evidence of global warming can be found in plants. The leading cause of global warming is the ongoing burning of fossil fuels, which releases carbon dioxide into the atmosphere. Although carbon dioxide largely harms the environment, the other greenhouse gases have a large impact in the atmosphere. Throughout the world, various nations have been joining to help prevent or slow the process of global warming. The issue of global warming affects nature, people, and the economy. Scientists directly link disease to global warming. When people are trying to get others involved in the cause, a common problem that arises is the lack of motivation. In conclusion, the world needs to put forth a stronger effort to prevent global warming. And the mitigation of global warming, we should do from ourselves, from the little things around.Text 10This article introduces what is global warming firstly, moreover there is a dispute lies in whether or not the global warming caused by human or results from the natural turnabout. There is a series figure point out that during the past 70 years, the earth has been hotter than at any other time in the last millennium which only spend few decades. The rising temperature trend can not be explained simply, it’s a consequence of 2 centuries of pollution .What’s more, due to the inherent inertia of this trend , we cannot immediately stop but only slow down. In fact, carbon dioxide levels in the atmosphere are rising for a long time ,moderating temperature swings and extremes, but our pollution is now strongly enhancing this greenhouse effect. However because the climate machine is complex, the sunspot cycle also play a role in it as well as volcanic eruptions. Attempting to pin down the true variation in global temperatures over the past thousand years is difficult because there still are evidences which can deny it. But of course , this was not the intention of the experiment at all . Indeed ,it is only in recent decades that the pollution effect of human activities on the global environment has been thought of in these terms. Even if both temperatures and sea levels would continue to rise for centuries to come, we are going to face the changes to our environment. And our children and their descendants are going to find the earth a very different place.Text 11The principal risks associated with nuclear power arise from health effects of radiation.The radiation mainly comes form the radioactive material.They can penetrate deep inside the human body where they can damage biological cells and thereby initiate a cancer. If they strike sex cells, they can cause genetic diseases in progeny.But the rate of the latter is far less than the former. Reactor accidents is also one of the risk of nuclear power.But the nuclear power plant design strategy for preventing accidents ,back-up system and mitigating their potenti al effects is “defence in depth”, so they happen probability is exceedingly small. If they all fails,very high radiation doses can destroy body functions and lead to death within 60 days.The radioactive waste products from the nuclear industry must be isolated from contact with people for very long time periods. The bulk of the radioactivity is contained in the spent fuel, which is quite small in volume and therefore easily handled with great care. At other radiation problems，for example, exploitation of materials and transport of radioactive materials also produce radiation.The effects of routine releases of radioactivity from nuclear plants depend somewhat on how the spent fuel is handled.Text 15Genetically modified food caused a fierce debate in the modern society, especially in long agrarian tradition and vocal green lobbies in the country。
小学上册第15次英语自测题
小学上册英语自测题英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.The ________ (生态研究机构) contributes valuable insights.2.I like to ride my _______ (我喜欢骑我的_______).3.What do we call a small, furry animal kept as a pet?A. FishB. CatC. LizardD. BirdB4.The cat is very ________.5. A ______ (土壤测试) can help gardeners.6. A dolphin is known for its playful ________________ (性格).7.The movie is ___. (exciting)8.My _____ (老师) teaches us about plants and animals. 我的老师教我们关于植物和动物的知识。
9.My uncle gave me a rare _________ (玩具) from his collection.10.I can create a _________ (玩具运动会) with all my sports toys.11.What is the main ingredient of the sun?A. OxygenB. HydrogenC. HeliumD. Carbon12.What is the main ingredient in pizza dough?A. RiceB. FlourC. CornD. SugarB13.What do you call the distance around a circle?A. RadiusB. DiameterC. CircumferenceD. Area14.How many continents are there?A. 5B. 6C. 7D. 8答案:C15.Which instrument has black and white keys?A. GuitarB. ViolinC. FluteD. PianoD Piano16.The ________ (种植技术) evolves over time.17.What is the main purpose of a computer?A. To eatB. To writeC. To computeD. To draw18.What do we call a baby rabbit?A. KidB. PupC. BunnyD. KitD19.What is the capital of Portugal?A. LisbonB. PortoC. MadridD. BarcelonaA20.I want to _______ (访问) my grandparents.21.What is the freezing point of water?A. 0 degreesB. 32 degreesC. 100 degreesD. 212 degreesA22.What do we call the movement of people from one place to another?A. TravelB. MigrationC. CommuteD. AdventureB23. A chameleon can shift its color to communicate or ______ (伪装).24.What is the name of the famous canyon in Arizona?A. Grand CanyonB. Antelope CanyonC. Zion CanyonD. Bryce CanyonA Grand Canyon25.They are _____ (friends/enemies) forever.26.My favorite fruit is _____ (banana/apple).27.I enjoy reading ______ before I sleep.28.What do we call a person who studies the interactions between living organisms and their environment?A. EcologistB. BiologistC. ZoologistD. BotanistA29.The __________ can be quite unpredictable in spring. (天气)30.My cat sleeps on my ______ (床).31.The musician plays the _____ (小提琴) in the orchestra.32.How many players are there in a hockey team?A. 5B. 6C. 7D. 8B33.An atom with a positive charge is called a _____.34.What do you call the sound a cow makes?A. BarkB. MeowC. MooD. Roar35.The boy has a new ________.36.What do we call the place where we can see many different kinds of fish?A. AquariumB. ZooC. MuseumD. ParkA37. A snake can be very ______.38.What is the term for a baby duck?A. GoslingB. DucklingC. ChickD. FryB39.The chemical symbol for gold is ______.40.Which animal is known for its ability to fly?A. FishB. BirdC. FrogD. HorseB41.We have science class on ___. (Friday)42.My brother is a _____ (学生) exploring different subjects.43.The __________ (历史画作) depict important moments.44.The __________ is a large body of ice moving slowly down a mountain. (冰川)45.The process of crystallization separates solids from _______.46. A _____ (花园项目) can engage students in science.47.The chemical formula for water is ______.48.My brother loves to __________ (做实验) with science.49.He is my best __________.50.The chemical formula for sodium citrate is _______.51. A ____ has sharp spines and can protect itself.52.I like to __________ (动词) my __________ (玩具名) with my friends.53.The chemical symbol for selenium is ______.54.The chemical formula for isobutyric acid is ______.55.What is a baby sheep called?A. CalfB. KittenC. LambD. PuppyC56.What is the main ingredient in pizza?A. DoughB. RiceC. BreadD. Salad57.My brother is very __________ (幽默的).58.What do we call the act of speaking to an audience?A. SpeechB. LectureC. PresentationD. All of the above59.Which planet is known for its rings?A. JupiterB. SaturnC. UranusD. NeptuneB60.Which instrument is often used to measure temperature?A. BarometerB. ThermometerC. SpeedometerD. RulerB61.What is the largest mammal in the world?A. African ElephantB. Blue WhaleC. GiraffeD. HippopotamusB62.The _______ (The War of 1812) highlighted tensions between the US and Britain.63.I can create a fantasy world with my toy ________ (玩具名称).64.The most abundant element in the universe is ______.65.The ancient Greeks used ______ (戏剧) for entertainment.66.I have a ________ (布娃娃) that I carry everywhere.67.What do we call the act of encouraging personal responsibility?A. AccountabilityB. OwnershipC. LeadershipD. All of the AboveD68.What do you call a collection of stars?A. GalaxyB. PlanetC. AsteroidD. CometA69.What do we call the tallest mountain in the world?A. K2B. KilimanjaroC. EverestD. DenaliC70.She is ___ a picture. (drawing)71.What do we call the largest organ in the human body?A. HeartB. SkinC. LiverD. BrainB72.What do you call the main character in a story?A. HeroB. VillainC. ProtagonistD. AntagonistC73.My dad is my superhero and _______ (我爸爸是我的超级英雄和_______).74. A ____ can often be found resting in the shade.75.What is the main component of Saturn's rings?A. IceB. RockC. DustD. Gas76.The ant works _______ (努力) to gather food.77.I want to learn how to _______.78.How do you say "hello" in Chinese?A. Ni haoB. KonnichiwaC. AnnyeongD. Hola79.The bird is flying in the ______.80._____ (mulch) helps retain soil moisture.81.The _______ (Roman Empire) expanded across Europe, North Africa, and the Middle East.82.The flamingo is known for its long _______ (腿).83. A ____ is known for its ability to fly great distances.84. A __________ is a region with distinct climate and wildlife.85.An acid can turn litmus paper _____.86.古代的________ (currencies) 促进了商业活动的进行。
Solid_15
Outline
Electrons in crystals Electrons in a periodic potential Bloch Theorem Quantitative calculations for nearly free electrons Equivalent to Bragg diffraction Energy Bands and standing waves at the Brillouin Zone Boundary Energy gaps Energy Bands in three dimensions Metals vs insulators - simple arguments (Read Kittel Ch 7)
n
Sums and Integrals over k points
We often need to sum or integrate over k 1) to get total quantities 2) To use rules like “”two electrons per state” We can use idea of periodic boundary conditions on box of size L x L x L Exactly the same as for phonons, electrons in a box,... Volume per k point = (2π/L)3 Total number of k points in in BZ
where T is any translation
Albert_Einstein(爱因斯坦)简介
I INTRODUCTION 1.1 Einstein, Albert (1879-1955), German-born American physicist and Nobel laureate, best known as the creator of the special and general theories of relativity and for his bold hypothesis concerning the particle nature of light. He is perhaps the most well-known scientist of the 20th century. 1.2 Einstein was born in Ulm on March 14, 1879, and spent his youth in Munich, where his family owned a small shop that manufactured electric machinery. He did not talk until the age of three, but even as a youth he showed a brilliant curiosity about nature and an ability to understand difficult mathematical concepts. At the age of 12 he taught himself Euclidean geometry.
Syllabus
SyllabusChina in Global EconomySpring, 2010Instructor: Dr. Li JingClassroom: Hist.209Class time: Thursday, 1:30pm—4:20pmCourse Description and ObjectiveCourse DescriptionThis course offers an opportunity for international students to begin studying the Chinese economy in the era of globalization and the interaction between China and the rest of world. It aims to develop the learners’ understanding of the process of China’s economic reforms and opening-up policy, how China was involved into the global economic circulation, it will be conducive to improving the learners’ sense of awareness in economics. The contents of this course is issues-oriented, it covers issues emerged in the last 30 years, and the analysis on issues are also based on the related theory.There are three parts in the course.The first part covers a number of issues areas that together provide an answer to the questions of enterprises reform, financial system reform, three rural problems, resource, environment and sustainable development of China. It will help the learners to get a general structure of the structural reforms and its outcomes.The Second part covers the interactions between China and world economy from the foreign trade, foreign investment and economic adjustment under the WTO frame work, the relations between China and its top trade partners.The third part covers China’s macroeconomic policy since 1990, fiscal policy, monetary policy, exchange rate policy and China’s response in times of crisis. It will address and compare China’s stimulus package and its outcomes during Asian Crisis (1997-1998) and global financial crisis (2008- ).The design of the course does not assume prior systematic knowledge about China or the Chinese economy. The students can expect to build a solid knowledge basis for learning, more systematically, about China and China’s ties with the rest of the world.Learning OutcomesBy the end of the course, students shoulda) Well understand China’s roadmap in economic reform and opening- up policy, especially the logic behind it.b) Well understand the Chinese economic features in the era of globalization and tasks ahead for China.c) Build the capability of studying the Chinese economy with economics knowledge. Prerequisite: principles of economics or permission of department.Course RequirementsStudents are expected to read through the articles selected for each week before the class convenes. In order to better comprehend the course readings and in-class discussions, however, students are strongly encouraged to refer to the following surveys of the Chinese economy:1.Angus Maddison, Chinese Economic Performance in the Long Term (OECD Development Center Studies, 1998).2.Wu Jinglian, Understanding and Interpreting Chinese Economic Reform(Thomson/South-Western, 2005).3.Barry Naughton, The Chinese Economy: transitions and growth, (MIT Press, 2007).4.Barry Eichengreen, ed., China, Asia, and the New World Economy (Oxford University Press, 2008).(The above books on reserve in the American University Program office)5.Wang Mengkui, China’s Economic Transformation Over 20 Years( Foreign LanguagesPress , Beijing), 20006.Li Jingwen, The Chinese Economy into the 21st Century, ( Foreign Languages Press , Beijing),2000Each student will be asked to make a presentation and lead a discussion based on a topic assigned for the week. The discussion shall be based on but not limited to the weekly readings assigned.The students will be grouped, and each group will participate in the in-class discussion; each group is required to make a presentation at the last class. The topic shall be based on the topics of each week but not limited to the weekly readings.In the fifth week, each student must present a one-page ‘writing plan’ for the term paper, which is due the last day of the course. Use the Chicago Manual of Styles for formatting the paper and observe the usual rules of academic integrity.Required Work and Grading PolicyYour final grade will be determined by the following:1.Attendance 15%2.In- Class group discussion and presentation 10%3.Term Report Presentation ( in group, in the last class) 10 %4.Individual presentation 15%5.Term paper 50%（should be personal）Grades are on a 100 points scale:90-10080-89 70-79 60-69 59- AB C D ECLASS SCHEDULEWeek Topics Lecture (hours)Otheractivities01 Chapter1 An Review on the Chinese EconomyThe roadmap of China’s Reforms and Opening-up302 Chapter 2 Reform of Enterprises (SOEs and SMEs)2In –classdiscussion03 Chapter 3 China’s Financial System and Supervision 304 Chapter 4 Three Rural Problems 305 Chapter5 Resource, Environment and Sustainabledevelopment2In –classdiscussion06 Chapter 6 Foreign Trade Development 307 Chapter 7 China’s Inward & Outward FDI and Other Investments308 Chapter 8 China’s WTO Entry: A Long March toGeneva2In –classdiscussion09 Chapter 9 Bilateral Ties between China and Its Top 3Trade Partners2In –classdiscussion10 Chapter10 China’s Macroeconomic Policy Since 1990311 Chapter11 China’s stimulus package in Time of Crisis 312 Chapter12 An Conclusion and Tasks Ahead for China 1 Term report Presentation Feedbacks Hand in the term paperWork SchedulePart I Basic Reforms and OutcomesWeek one Chapter 1 An Review on the Chinese EconomyThe roadmap of China’s Reforms and Opening-upWang Mengkui, China’s Economic Transformation Over 20 Years( Foreign Languages Press , Beijing), 2000, Chapter 4,5Li Kui-wai, The two decades of Chinese economic reform compared, China & World Economy, No. 2., 2001Liu Guoguang, Economic Reform and Development in China,China and World Economy No.1, 1998Conference News 30 Years of Economic Reforms in China：Retrospect and Outlook (81) , China & World Economy, No.1,2008Hu Angang, China’s Economic Growth and Poverty Reduction(1978-2002), edited by Wanda Tseng and David Cowen, India’s and China’s Recent Experience with Reform and Growth, IMF, 2005 . Chapter 3Week Two Chapter 2 Reform of Enterprises (SOEs and SMEs)Wang Mengkui, China’s Economic Transformation Over 20 Years( Foreign Languages Press , Beijing), 2000,Jiang Xiaojuan ,The Globalization of China's Economy and the Formation and Development of En terprise Groups ,China & World Economy, No. 1 ,2000Shiyong Zhao, Government Policies and Private Enterprise Development in China： 2003-2006, China & World Econom y, No.4.2009Wang Zhongyu, State-owned Enterprise Reform in a Major Stage ,China & World Economy, No. 2,1997Zhang Chunlin, Revisiting China’s SOE Reform Strategy, China & World Economy, No.2, 2002Week Three Chapter 3 China’s Financial System and SupervisionBarry Naughton, China's Financial Reform: Achievements and Challenges, BRIE Working Paper 112.1998, BRIEChen Yuan, Financial System Reform and Economic Development in China, edited by Wanda Tseng and David Cowen, India’s and China’s Recent Experience with Reform and Growth, IMF, 2005Xie Ping, Financial Reform in China: Review and Future Challenges, China & World Economy, No. 5, 1999Xia Bin China Ready for Adopting a Universal Banking System? , China & World Economy, No. 2, 2001Week Four Chapter 4 Three rural problemsWang Mengkui, China’s Economic Transformation over 20 Years (Foreign Languages Press, Beijing), 2000, Chapter 3 Reform of Economic Structure in China’s Rural AreaZhu Ling, Gender Inequality in the Land Tenure System of Rural China, China & World Economy, No. 2, 2001Zhigang Xu RanTao, Urbanization, Rural Land System and Social Security in China, China & World Economy,No.6, 2004LiZhou, Public Goods, Environmental Protection,and the Development Paradigm in Rural China , China & World Economy , No.6,2004Tao Ran Liu Mingxing, Rural Taxation and Government Regulations in China, China & World Economy, No.2, 2003Yang Yao, Village Elections, Accountability and Income Distribution in Rural China, China & World Economy, No.6, 2006Fang Cai Meiyan Wang, A Counterfactual Analysis on Unlimited Surplus Labor in Rural China , China & World Economy, No.1, 2008Week Five Chapter 5 Resource, Environment and Sustainable developmentLi Jingwen, The Chinese Economy into the 21st Century, (Foreign Languages Press , Beijing), 2000, Chapter 17 The EnvironmentWarwick J. McKibbin, Global Energy and Environmental Impacts of an Expanding China, China & World Economy, No.4, 2006Pan Jiahua, Du Yaping, Environmental Degradation as a Threat to China's Food Security, China & World Economy, No. 1, 1998Shi Min, Environmental Protection in China: Existent Problems and Improvement Measures, China & World Economy, No. 4, 1998Chunsheng Tian, Sino-Russian Energy Cooperation and Geo-Strategic Issues, China & World Economy, No.3, 2005Dan Shi Energy Industry in China：Marketization and National Energy Security, China & World Economy, No.4, 2005Jason Zunsheng Yin David Forre, Elasticity of Energy Demand and Challenges for China’s Energy Industry, China & World Economy, No.4,2006Part II The Interaction between China and World EconomyWeek Six Foreign Trade DevelopmentNicholas R. Lardy, Trade Liberalization and its role in Chinese Economic Growth, edited by Wanda Tseng and David Cowen, India’s and China’s Recent Experience with Reform and Growth, IMF, 2005 .Chapter 7Hung-gay Fung, China’s Foreign Trade and Investment：An Overview and Analysis , China & World Economy, No.3, 2005Pingyao Lai ,China’s Foreign Trade：Achievements, Determinants and Future Policy Challenges, China & World Economy, No.6, 2004Fung Hung－gay, Are China’s Trade Policies Effective？China & World Economy, No.1, 2003 Week Seven China’s Inward & Outward FDI and Other Investments Xiaojuan Jiang, Prospects and Analysis of FDI in China, China & World Economy, No.4, 2005Judith M. Dean, “Are foreign investors attracted to weak environmental regulations? Evaluatingthe evidence from China,” Journal of Development Economics, November 2008 (on-line).Furong Jin Keun Lee Yee-Kyoung, Changing Engines of Growth in China：From Exports, FDI and Marketization to Innovation and Exports, China & World Economy,No.2,2008Laijun Luo Louis Brennan Chan , Factors Influencing FDI Location Choice in China＇s Inland Areas, China & World Economy, No.2, 2008Zhang Honglin，Why Does China Receive So Much Foreign Direct Investment？China & World Economy，No.3, 2002Jiang Xiaojuan, New Regional Patterns of FDI Inflow：Policy Orientation and Expected Performance, China & World Economy, No.2, 2002Foreign Capital Utilization in China: Prospects and Future Strateg y, World Bank,《中国利用外资的前景和战略》，世界银行主编，中信出版社，2007（This book is written in both Chinese and English）Week Eight China’s WTO Entry: A Long March to GenevaSong Hong,The Impact of China's WTO Accession on Industrial Development, China & World Economy, No. 1 , 2000Liping He, Xiaohang Fan, Foreign,China & World Economy, No.5, 2004Li Yuefen, Economic Implications of China's Accession to the WTO,China&World Economy，No.2, 2003Guo Kesha，Comprehensive Impacts of China's WTO Entry on Its Industrial Sector，China & World Economy，No.2,2003Zhang Xiaopu , Chinese policy options on international capital flow after WTO accession, China &World Economy，No.3, 2003Changhong Pei Lei Peng, Responsibilities of China after Accession to the WTO，China & World Economy， No4, 2007Wang Yu，some important issues concerning China’s macroeconomic management after WTO entry –interview with prof. Lawrence lau, China &World Economy，No.5, 2003Kanamori Toshiki, China's Economy and Financial Market after the WTO Entry, China &World Economy，No 6, 2001Week Nine Bilateral Ties between China and Its Top 3 Trade Partners Changhong Pei, Analysis of the Changes in the Growth of Japan＇s Direct Investment in and Trade with China , China & World Economy,No.6, 2005Willem F. Duisenberg, China and the Euro Area in a Global Perspective, China & WorldEconomy, No.3, 2002Zhao Longyue and Wang Yan, “Trade Remedies and Non-Market Economies: Economic Implications Of The First US Countervailing Duty Case On China”，World Bank Research Working papers, December 2008, pp. 1-50.David Scott, “China-EU convergence 1957–2003: towards a ‘strategic partnership’”, Asia Europe Journal, Volume 5, Number 2, June 2007, pp. 217-233.Wing Thye Woo, “Dealing sensibly with the threat of disruption in trade with China: the analytics of increased economic interdependence and accelerated technological innovation,” Economic Change and Restructuring, Volume 40, Numbers 1-2, June 2007，pp. 1-26.Bibo Liang , Political Economy of US Trade Policy towards China, China & World Economy, No.5, 2007He Li Ping, Sino-Japanese economic relational: a Chinese perspective，China & World Economy, 2003.5Part III China’s Macroeconomic PolicyWeek Ten China’s Macroeconomic Policy Since 1990Olivier Blanchard Francesco Gi, Rebalancing Growth in China：A Three-Handed Approach, China & World Economy, No.4, 2006Stephen S. Roach, On Next Asia: Opportunities and Challenges for a New Globalization, Chapter 3 , Chinese Rebalancing, John Wiley & Sons, Inc, 2009Yu Yong-ding, A Review of China's Macroeconomic Development and Policies in the 1990s China & World Economy, No. 6 ,2001Week Eleven China’s stimulus package in Time of CrisisYu Yongding, China's Macroeconomic Situation and Future Prospect, China & World Economy, No.1, 1999Yu Yongding, China 1999-2000: The Macroeconomic Situation and Financial Reforms, China & World Economy, No. 1, 2000Xin Wang, China as a Net Creditor：An Indication of Strength or Weaknesses？China & World Economy, No.6, 2007Hung-Gay Fung Qingfeng, China’s Outward Direct and Portfolio Investments Wilson, China & World Economy, No.6, 2007Week Twelve A Conclusion and Tasks Ahead for ChinaGuiyang Zhuang, How Will China Move towards Becoming a Low Carbon Economy？China & World Economy No.3, 2008Shi Dan, Energy Restructuring in China：Retrospects and Prospects, China & World Economy No.4, 2008Xin Wang, China as a Net Creditor：An Indication of Strength or Weaknesses？China & World Economy, No.6, 2007Jonathan Anderson，Capital Account Controls and Liberalization：Lessons for India and China, edited by Wanda Tseng and David Cowen, India’s and China’s Recent Experience with Reform and Growth, IMF, 2005 Chapter 3。
药物化学原理课件-Lecture-03
1Summary of Last lecture •Lead Modification•Search for the active part (Pharmacophore, 药效团)•Structure-activity relationship (SARs)•Functional group modification •Drug-like molecules •Structure modifications•Bioisoterism (生物电子等排原理)•To increase potency and therapeutic index •To increase oral bioavailability•Pharmacokinetics, Metabolism andPharmacodynamics (药动，药代和药效)2Summary of Last Lecture (cont’d)•Pharmaceutical Phase•Selection of administration route (给药途径)to optimizeabsorption and distribution and or most appropriate formulation for maximal benefits •Pharmacokinetic Phase•Fate of the drug in the body (ADME), the ration ofadministrated dose to the concentration of the drug at the site of action as the function of time •Pharmacodynamic Phase•Quality of the drug-target response (maximal activity and selectivity, minimal toxicity), and nature and intensity of the biological response)3Scheme of in vivo Events CirculationBoundUnboundDistributionIntravenous Fat StorageLiver Metabolism:Metabolic activation Metabolic degradationKidney Intestine LungUrine Faeces Expired airAdministration of a drug AbsorptionMembrane BarrierMembrane BarrierParenteral RouteEnteralRouteB i o l o g i c a l l y a v a l i a b l eInteraction w/the receptor site of the target organBiological Response4Pharmacodynamic Phase•The phase of great interest to the medicinal chemist asit deals directly with the nature and the quality of the interaction of the drug with its biological target •The challenge is to maximize the potency and to minimize undesired effects of the molecule•Try to design drugs with the optimal size, shape,hydrophilic-lipophilic ratio, and disposition of functional groups•The closer the fit obtained between the receptor site and the molecules, the more selective will be the drug in eliciting only the expected biological response5Med. Chem. LectureOctober 14, 2009Lei Fu （傅磊）, Ph.D.leifu@ 上海交通大学药学院药物化学课题组6Outline•Term Paper Assignment •Term Paper Preparation •Receptor (受体)•Drug-Receptor Interactions7Course Content (cont’d)•Lectures (September 16, 23, 30)•No lecture on October 7th •Lectures (October 14, 21, 28)•Term paper assignment (by September 30)•Term paper preparation (about one month)•Term paper presentation (November 4, 11)•Term paper due (w/ppt, November 2nd )8Outline•Term Paper Assignment •Term Paper Preparation •Receptor (受体)•Drug-Receptor Interactions9Scheme of in vivo EventsCirculationBoundUnboundDistributionIntravenous Fat StorageLiver Metabolism:Metabolic activation Metabolic degradationKidney Intestine LungUrine Faeces Expired airAdministration of a drug AbsorptionMembrane BarrierMembrane BarrierParenteral RouteEnteralRouteB i o l o g i c a l l y a v a l i a b l eInteraction w/the receptor site of the target organBiological Response10Receptor (受体)Definition• A receptor is the site of drug action, which isultimately responsible for the pharmaceutical effect•Molecular structure in or on a cell thatspecifically recognizes and binds to acompound and acts as a physiological signal transducer, or mediator of, an effect (IUPAC)11Receptor (cont’d)•Mostly membrane-boundproteins that selectively bind small molecules, referred to as ligands, that cause somephysiological response •Generally integral proteins that are embedded in thephospholipid bilayer of cell membranesNeurotransmitter receptorsLigands12Receptor (cont’d)•Once dissociated fromthe membranes, they generally lose their integrity•Typically characterizedin terms of their function rather than by their structural propertiesThe Nicotine Receptor13Outline •Term Paper Assignment •Term Paper Preparation •Receptor (受体)•Drug-Receptor Interactions14Drug-Receptor InteractionsThe interaction is an equilibrium rather than anone-to-one interaction•Drug (200Mw, 10mg):(6.02x1023)(10x10-3)/200=3x1019•Each cell: 1010molecules•Human organism: 3x1013cells or 3x1023molecules •Cell molecules/drug molecules = 10415Drug-Receptor InteractionsThe measurement of the drug-receptor interactions•The dissociation constant K d•K d = [drug][receptor] / [drug-receptor complex]•The smaller the K d , the more stable is thecomplex, and the greater is the affinity of the drug for the receptor16Types of Interactions1.Covalent Bonds2.Ionic (or electrostatic) Interactions3.Ion-Dipole and Dipole-Dipole Interactions4.Hydrogen Bonds5.Charge-Transfer Complexes6.Hydrophobic Interactions17Covalent Bonds •The strongest bond, worth -40 to -110 kcal/molin stability•Seldom formed by a drug-receptor interaction,except with enzymes and DNA18Ionic (or electrostatic) Interactions•At physiological pH=7.4, the amino side chains of arginine, lysine, histidine areprotonated, and provide a cationic environment; acidic groups are deprotonated to give anionic groups•The ionic interaction can be effective at distances farther than those required for other types of interactionsExample of an electrostatic interaction ΔG o = -5 to -10 kcal/molPivagabine is an antidepressant drug Wavy line represents the receptor surface19Ion-Dipole & Dipole-Dipole•As a result of electro-negativity difference between C and X (O, N, S, F, Cl etc.)•Asymmetric distribution of electrons produces electronic dipoles •A dipole-dipoleinteraction is weaker than an ion-dipole interactionExample of Ion-Dipole & Dipole-Dipole InteractionsΔG o = -1 to -7 kcal/molWavy line represents the receptor surface20Hydrogen Bonds•A type of dipole-dipoleinteraction formed between H and an electronegative atom and other electro-negative atom with a pair ofnonbonding electrons: N, O, F •H is the only atom carries a positive charge atphysiological pH whileremaining covalently bonded in a moleculeExample of H-bond interactions ΔG o = -3 to -5 kcal/molSalicylic acid (水杨酸)is used in wart removal remediesWavy line represents the receptor surface21Charge-Transfer Interactions•Between e -donor and e -acceptor•The donor will transfersome of its charge to the acceptor, forming a charge-transfer complex•Donor: aromatic moieties,π-electrons, O, N, S•Acceptor: e --deficient π-orbitalsExample of a charge-transfer interaction ΔG o = -1 to -7 kcal/molChlorothalonil (百菌清)is a fungicide Wavy line represents the receptor surface22Hydrophobic Interactions•In the presence of a nonpolar molecule or region of a molecule, the surrounding water molecules orient themselves and are in a higher energy state•When meet, these watermolecules become disordered in an attempt to associate with each other •ΔG(↓) = ΔH –T ΔS(↑)Example of hydrophobic interaction ΔG o = -0.7 kcal/molButamben is a topical anesthetic drug Wavy line represents the receptor surface23Example of Multiple Interactions Dibucaine (二丁卡因，局部麻醉剂)24Example of Multiple InteractionsDibucaine (二丁卡因，局部麻醉剂)25Example of Multiple Interactions Dibucaine (二丁卡因，局部麻醉剂)26Conclusions•Cooperativity by several types of interactions is critical.The effect of this cooperativity is that several rather weak interactions may combine to produce a strong interaction•ΔG = ΔH -T ΔS•To a first approximation, enthalpy (ΔH) term will beadditive, then, translational entropy (ΔS) is lost•Charge groups bind more strongly than polar groups,which bind more tightly than nonpolar groups27QuizIndicate what drug-receptor interactions are involved at each arrow shown1.Ion-dipole interaction2.Dipole-dipole interaction3.Hydrophobic effect4.Hydrogen bonding5.Electrostatic interaction and/or hydrogen bondingabdec28Quiz (answer key)Indicate what drug-receptor interactions are involved at each arrow shown1.Ion-dipole interaction2.Dipole-dipole interaction3.Hydrophobic effect4.Hydrogen bonding5.Electrostatic interaction and/or hydrogen bondingabdecAnswer key: a-5, b-4, c-3, d-2, and e-1。
海藻糖在生育力保存中的应用
海藻糖在生育力保存中的应用田婷【摘要】肿瘤诊疗技术的进步显著提高了患者的生存率,但放化疗可能造成人类生育力的下降乃至丧失.如何有效保存生育力已成为近年来研究的热点.海藻糖属于非渗透性冷冻保护剂,是一种具有特殊生物学性能的双糖,能够在于燥、脱水、冷冻等恶劣条件下有效保护蛋白质等大分子不变性失活.随着研究的逐步深入,海藻糖已被广泛应用于生育力保存等医学领域中,有学者将其用于保存精子、精原干细胞、卵母细胞、胚胎、卵巢组织和睾丸组织并取得了显著成果.综述海藻糖的生物学性质、作用机制假说以及在生育力保存中的应用研究现状和最新进展.【期刊名称】《国际生殖健康/计划生育杂志》【年(卷),期】2015(034)003【总页数】3页(P248-250)【关键词】海藻糖;低温保存;卵母细胞;卵巢;精子【作者】田婷【作者单位】230000 合肥,安徽医科大学第一附属医院生殖医学中心【正文语种】中文近年来，肿瘤治疗已取得了巨大进步，显著延长了患者的生命。
但同时，肿瘤及其治疗也会导致女性的卵巢功能受损[1]，肿瘤后遗症带来的生育难题也备受关注。
生育力保存主要包括卵子、精子、胚胎、精原干细胞及睾丸组织的冷冻保存以及卵巢组织低温保存及再植。
目前，低温保存技术主要包括慢速冷冻法和玻璃化冷冻法。
相对于慢速程序化冷冻，玻璃化法具有操作简单，耗时短，费用低，冻融效果好等优点。
冷冻保护剂包括：渗透性保护剂，如乙二醇、丙二醇、二甲基亚砜等；非渗透性保护剂，如聚乙二醇、海藻糖和蔗糖等。
适宜的冷冻保护剂成为近些年研究的热点，海藻糖在此方面的作用也逐渐得到重视。
1 海藻糖的生物学特性海藻糖是由两个葡萄糖分子以1，1-糖苷键构成的非还原性糖，有3种异构体即海藻糖（α，α）、异海藻糖（β，β）和新海藻糖（α，β）。
海藻糖是性质最为稳定的天然双糖，几乎不能被一般的酶类分解，但在人体内可被水解成葡萄糖。
当生物体处于高温、高寒、高渗透压、低温冷冻、有毒试剂等恶劣环境条件下时，海藻糖可以保护机体内蛋白质等大分子的活性。
当代大学生与过去大学生的不同英语作文
当代大学生与过去大学生的不同英语作文全文共3篇示例，供读者参考篇1The College Experience: Then and NowAs a modern college student, it's hard not to notice the vast differences between my daily life and that of students from previous generations. From the way we learn and access information to our social lives and career prospects, the collegiate experience has undergone a seismic shift in recent decades. In this essay, I'll explore some of the key distinctions between being a college student today versus in the past.Perhaps the most obvious divergence lies in the realm of technology. Previous generations of college-goers had to rely heavily on physical libraries, textbooks, and in-person lectures to acquire knowledge. In contrast, we modern students have the entirety of human knowledge quite literally at our fingertips thanks to the internet and online databases. Need to research a topic for a paper? Just a quick Google search away. Missed a lecture? No problem, most professors post recordings or slides online.This unprecedented access to information has radically altered the way we learn and study. While students of yesteryear may have spent countless hours poring over books in the library stacks, we can now instantly pull up relevant sources from the comfort of our dorm rooms (or really anywhere with a Wi-Fi connection). On the one hand, this increased efficiency allows us to gather information more quickly. However, it has also led to a culture of seeking out bite-sized snippets rather than deeply engaging with entire texts - a intellectual habit past students may have been more accustomed to.Beyond just academics, technology has transformed nearly every facet of the collegiate social experience as well. In thepre-internet era, students had to rely on flyers, bulletin boards, and word-of-mouth to hear about parties, events, or meeting new people. Nowadays, students can instantly broadcast their activities and connect with peers through social media, group chats, and event planning篇2Modern University Life vs The Good Old DaysAs a current university student, I can't help but wonder how different my college experience is from that of previousgenerations. Sure, we're all young adults pursuing higher education, but the realities of university life have evolved significantly over time. Let me take you on a journey to explore the contrasts between contemporary university students and those who walked the hallowed halls decades ago.To begin with, the sheer diversity on campuses today is remarkable. Colleges and universities have become melting pots of cultures, ethnicities, and backgrounds. Compared to the more homogeneous student bodies of the past, we interact with peers from all corners of the globe, enriching our perspectives and broadening our worldviews. This exposure to different customs, beliefs, and experiences is invaluable in preparing us for the increasingly interconnected world we live in.Technology has also reshaped the university experience in profound ways. While our predecessors relied on physical libraries, handwritten notes, and face-to-face interactions, we have the world at our fingertips. Online resources, digital textbooks, and virtual lectures have become the norm, allowing us to access information and attend classes from virtually anywhere. However, this convenience comes with its own challenges, as we must navigate the pitfalls of digital distractions and information overload.The way we socialize and build connections has also undergone a transformation. In the past, students gathered in common areas, dorm rooms, or campus hangouts to forge lasting friendships and bonds. Today, many of our social interactions take place in the virtual realm, through social media platforms, messaging apps, and online gaming. While this digital connectivity has its advantages, some might argue that it lacks the depth and authenticity of face-to-face interactions.Mental health and well-being have become increasingly prominent concerns for contemporary university students. The pressures of academic demands, financial burdens, and the constant need to curate an online persona can take a toll on our mental and emotional state. In contrast, past generations may have faced different stressors, but the ever-present nature of social media and the 24/7 connectivity we experience today were non-existent.Furthermore, the job market and career prospects have evolved drastically since our parents' or grandparents' time. The traditional paths to employment have become more convoluted, and the gig economy has emerged as a viable alternative. We must navigate a constantly shifting job landscape, honing notonly our academic skills but also our entrepreneurial mindsets and adaptability.Despite these differences, some aspects of university life remain constant across generations. The pursuit of knowledge, the thrill of intellectual discovery, and the camaraderie forged among peers are timeless experiences. The late-night study sessions, the spirited debates in lecture halls, and the lifelong friendships formed on campus transcend eras and unite us with those who came before.Yet, even in these shared experiences, the way we approach them may differ. For instance, while previous generations may have congregated in libraries or study groups, we may opt for virtual study sessions or collaborative online platforms. The methods may vary, but the underlying drive for academic excellence remains steadfast.As I reflect on these contrasts, I can't help but feel a sense of awe and gratitude for the opportunities afforded to us as modern university students. We stand on the shoulders of those who paved the way, benefiting from their sacrifices andhard-won progress. At the same time, we face unique challenges that demand resilience, adaptability, and a willingness to embrace change.In the end, the university experience is a transformative journey, regardless of the era. It shapes us intellectually, socially, and personally, equipping us with the tools to navigate anever-evolving world. While the specifics may differ, the core essence of higher education remains constant: to inspire curiosity, foster critical thinking, and empower us to make a positive impact on society.So, while we may lament the loss of certain traditions or wax nostalgic about the "good old days," let us also embrace the unique opportunities and challenges that define our contemporary university experience. For it is in navigating these complexities that we forge our own paths, carving out our identities and leaving an indelible mark on the tapestry of academia.篇3The Life of a Modern University Student: A Stark Contrast from the PastAs a current university student, I often find myself pondering the stark differences between my daily experiences and those of students from previous generations. While the fundamental purpose of higher education remains the same – the pursuit ofknowledge and academic growth – the world we live in today has transformed significantly, reshaping the university experience in ways our predecessors could have never imagined.One of the most glaring contrasts lies in the realm of technology. In the past, students relied heavily on physical libraries, books, and handwritten notes as their primary sources of information. Research was a painstaking process, involving countless hours spent sifting through stacks of dusty volumes and meticulously transcribing relevant passages. Today, the advent of the internet and digital resources has revolutionized the way we access and consume information. With a few clicks, we can access a vast repository of knowledge, scholarly articles, and online databases, streamlining the research process and making it more efficient than ever before.Additionally, the proliferation of laptops, tablets, and smartphones has transformed the classroom experience. No longer confined to traditional lecture halls or bound by the limitations of physical textbooks, we now have the ability to attend virtual classes, access course materials online, and collaborate with peers seamlessly through various digital platforms. This technological integration has not only enhanced our learning opportunities but has also fostered a more flexibleand dynamic educational environment, catering to the diverse needs and lifestyles of modern students.Another striking difference lies in the diversity and inclusivity found within today's university campuses. While past generations may have encountered more homogeneous student bodies, contemporary universities are melting pots of cultures, backgrounds, and perspectives. This rich tapestry of diversity not only enriches our academic discourse but also prepares us to navigate and thrive in an increasingly globalized world. We are exposed to a wide range of ideas, beliefs, and experiences, challenging us to broaden our horizons and cultivate a more inclusive and compassionate mindset.Furthermore, the societal expectations and pressures faced by modern university students have evolved significantly. In the past, the primary focus was often on academic achievement and intellectual pursuits. While these remain essential components of our educational journey, we are now expected to develop a well-rounded skill set that extends beyond the confines of the classroom. Extracurricular activities, internships, and networking opportunities have become crucial components of the university experience, as we strive to build a competitive edge and position ourselves for future success in the rapidly evolving job market.Mental health and well-being have also emerged as critical considerations for today's students. The pressures of academic life, coupled with the complexities of navigating personal and social spheres, can take a toll on our mental and emotional states. Unlike previous generations, where such issues were often overlooked or stigmatized, modern universities have recognized the importance of providing comprehensive support systems, counseling services, and initiatives to promote overall student well-being.Moreover, the concept of lifelong learning has gained significant traction in recent years. While our predecessors may have viewed education as a finite journey culminating in a degree, we are increasingly exposed to the notion that learning is a continuous process that extends beyond the boundaries of formal education. The rapid pace of technological advancements and evolving job markets necessitates a commitment to continuous skill development and adaptability, shaping our mindsets to embrace lifelong learning as a way of life.Despite these profound differences, there remains a unifying thread that connects us to our predecessors – the unwavering pursuit of knowledge and personal growth. Just as students of the past dedicated themselves to their studies and embraced thetransformative power of education, we too, strive to expand our intellectual horizons, challenge preconceived notions, and contribute to the ever-evolving tapestry of human knowledge.As I reflect on these contrasts, I am filled with a profound sense of gratitude for the opportunities and resources available to us as modern university students. Yet, I also recognize the invaluable lessons and wisdom we can glean from those who came before us. Their resilience, determination, and commitment to learning serve as a reminder that while the landscape may shift, the essence of the university experience remains rooted in a shared passion for intellectual exploration and personal growth.In conclusion, the life of a contemporary university student is a tapestry woven with the threads of technological advancements, diversity, holistic development, mentalwell-being, and lifelong learning. While these elements may have been foreign or minimally present in the past, they have become intrinsic components of our educational journey today. As we navigate this ever-changing landscape, it is our responsibility to embrace the opportunities before us while honoring the traditions and wisdom of those who paved the way. For it is through this delicate balance that we can truly unlock thetransformative power of higher education and shape a future that is both innovative and grounded in the timeless pursuit of knowledge.。
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分子间作用力的分配 (kJ·mol–1) 分子 Ar CO HI HBr HCl NH3 H2O 取向力 0.000 0.003 0.025 0.69 3.31 13.31 36.39 诱导力 0.000 0.008 0.113 0.502 1.00 1.55 1.93 色散力 8.5 8.75 25.87 21.94 16.83 14.95 9.00 总和 8.5 8.75 26.00 23.11 21.14 29.60 47.31
HCl 2. 偶极—诱导偶极作用 − δ + δ − + Ar HCl
δ+
+
+
HCl
HCl
3. 瞬间偶极—瞬间偶极作用
(色散力)
London色散力的体积效应
CH3CH2CH3 (C3H8) 丙烷 mp −190 C° bp −42 C° 气体@RT CH3(CH2)6CH3 (C8H18) 辛烷 −57 C° +125 C° 液体@RT CH3(CH2)18CH3 (C20H42) 二十烷 +37 C° +343 C° 固体@RT
练习：SO2和SF6之间有哪些范德华作用力？ 1) 偶极—偶极、偶极—诱导偶极、色散力 2) 偶极—诱导偶极、色散力 3) 偶极—偶极、色散力 4) 偶极—偶极、偶极—诱导偶极 5) 偶极—诱导偶极 6) 偶极—偶极 7) 色散力
二、氢键 X—H……Y (X, Y = F、O、N)
共价键 氢键
导带
Mg [Ne] 3s2
价(电子)带
a) 绝缘体 Eg
导带 2sp3
Cgas
Cdia,gas
Eg > 5.0 eV，绝缘体
Байду номын сангаас
价带
b) 导体
( a) 导体
( b)
c) 半导体
导带 3sp3 Eg=1.1 eV 价带
Si
三、固体的能带理论
1. 金属键 1900年 Paul Drüde (原子核 + 内层电子) + 价电子在材料中自由移动 原子果核
2. 能带理论
1928年 Felix Bloch 1927年 Walter Heitler & Fritz London
Li Cu [Ar] 3d104s1
[He]2s1
练习：下列各物种最稳定的是哪一个？ 最不稳定的是哪一个？ O22−, O2−, O2, O2+, O22+
Lecture 15 分子间作用力与固体能带理论
1. 分子间作用力 2. 氢键 3. 固体的能带理论
一、分子间作用力(范德华力)
1. 偶极—偶极作用 δ+ + δ− + δ − + − δ− δ− − δ+ δ+ δ− δ− −