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历年6级真题阅读翻译

历年阅读真题翻译1999年6月六级阅读译文Passage One我们有时认为惟有人类易受忧虑伤害，但紧张情绪似乎也影响了低级动物的免疫系统。

例如，在一次实验中，丹佛大学的行为免疫学家马克•朗顿斯拉格对24只老鼠进行了轻微的电击。

一半老鼠能通过转动笼子里的一个轮子切断电源，而另一半却不能。

朗顿斯拉格将两组老鼠配成对，每次一只老鼠转动轮子，它就能保护自己和无能为力的伙伴免遭电击。

朗顿斯拉发现，无能为力的老鼠免疫反应降至正常以下，但那些能够切断电流的老鼠却没有。

他认为，他所证明的是缺乏控制事件的能力会削弱免疫系统，而非经历本身。

其他研究者也同意他的看法。

杜克大学医学院的心理学家琼•伟斯已经证明：被允许控制不快刺激的动物不出现睡眠障碍，大脑化学成分也不发生变化，这些正是老鼠紧张的典型表现。

但是，如果动物遭遇过不能控制的情况，以后它们面对能控制的事件时行为就会被动。

这些发现加强了心理学家的猜疑，无助的经验或感知是压抑情绪中最有害的因素之一。

心情改变免疫反应最令人惊讶的例子之一是偶尔发现的。

1975年，罗切斯特大学医学院的心理学家罗伯特•阿德通过同时给老鼠喂糖精和注射抑制免疫系统的药使其胃部不适，使老鼠形成条件反射避开糖精。

因为把糖精和胃痛联系起来，老鼠很快就学会避开糖精。

为消除对糖精的厌恶，阿德再次给这些老鼠喂糖精，但这次没给药；他惊讶地发现一些老鼠死了，这些老鼠在以前形成条件反射期间吃的糖精最多。

他只能这样推测：他成功地使老鼠形成条件反射，现在仅用削弱其免疫系统的糖精就足以使其致死。

Passage T wo破坏自然资源和污染食物的事不断发生，这主要是因为对那些不顾后果肆意破坏环境的人难以追究法律责任。

通过立法、经济刺激和善意劝说等防止污染的努力遇到诉讼、个人和企业的否认及旷日持久的拖延——不仅在接受责任方面，更重要的是在有关其处理方面。

看来只有当政府决定采取税收优惠或牺牲生产时，才会主动改变。

保护人类的伟大宝库是一项最重要的责任，企业和我们对此的共识何在？如果有环境卫生专业人员到第一线来领导解决环境问题的时刻，这时刻便是现在。

历年英语六级真题阅读译文汇总

历年英语六级真题阅读译文汇总1999年1月六级试题译文Passage one译文很多美国人对有关食物的多数危险持极度歪曲、夸张的观点。

马萨诸塞—阿姆赫特大学食品科学及营养系主任佛卡斯·克拉斯代尔直率地说，如果被细菌污染的鸡肉的危险像一些人认为的那样大，“大街上就会到处躺满中毒的人。

”虽然公众越来越要求安全食品，但世界上没有这样的东西。

伯克利的加里福尼亚大学生物化学系主任布鲁斯·阿密兹指出，一棵植物中多达10%的重量是天然杀虫剂。

他说：“植物没有嘴和牙齿来保护自己，它们就使用化学战。

”许多自然生成的化学物质虽然量很小，但实验室化验却证明是强致癌物——可引起癌症的物质。

如果用食品添加剂的标准来衡量，蘑菇就会被禁止食用。

康乃尔大学的营养学家克利斯蒂娜·斯达克断言：“我们从食物中获得的天然化学物质比任何人造的东西都糟糕得多。

”然而问题并不那么简单。

尽管美国人没理由害怕坐在餐桌旁，但他们完全有理由要求食物和饮水安全有明显改进。

他们不知不觉地、不情愿地吸收了大量各种各样的危险化学物。

要是食物中已经含有天然致癌物，再加上几十种新的人造致癌物就不大明智了。

虽然大多数人能抵抗食物和水里的少量污染物，但至少一天少数人会因吃喝的东西而患癌症。

为使食物和供水质量更高，政府需提高管理标准，严格检查计划并强化执行政策。

食品工业应该修改某些人们长期接受的做法，或采用危险较小的做法。

最重要的也许是消费者将不得不学习如何正确处理和烹制食物。

需要解决从田间到加工场、再到厨房的整个食品供应过程中的全部问题。

O(∩_∩)O谢谢Passage two译文有些地球现象可以预计，但有的人说磁场是个例外。

磁场的强度波动，并从轴开始移动，每隔几十万年经历一次奇异的两极转换——这期间北极变成南极，南极变成北极。

但磁场是怎么产生的？为什么如此不稳定？两位法国地球物理学家的开创性研究为揭示这一奥秘提供了一些线索。

利用80米深海沉淀物的核心，他们测出了历时400万年，11次两极转换期间的磁场强度。

新21世纪大学英语课文第六单元texta的翻译

Unit 6 艾萨克·阿西莫夫的未来世界：医学艾萨克·阿西莫夫于1991年撰写了这篇文章，文章中的许多预言已经成为现实。

1.人人都认为预防疾病比试图治愈它更安全、更容易、更省钱。

2.医学界第一个伟大的胜利出现在1798年，当时人们发明了种痘。

于是，天花能够被预防了。

3.19世纪60年代，学界提出疾病的微生物理论，医生们开始发明出阻止细菌侵入人体以及人体一旦遭侵入后与之抗争的方法。

4.现在，我们能对付大多数细菌性疾病，但人类生命和健康最大的危险是所谓的退化疾病。

它们包括肌体的损坏，人们因此会遭受到癌症、心脏病、糖尿病等疾病的折磨。

5.医学界人士对如何配置我们的饮食以减少这些疾病的发病率了解甚多。

他们已学会如何用维生素使人的肌体保持较好的状态。

6.尽管我们已竭尽所能，但那些衰退疾病终将出现，人体将会完全垮掉。

因此，人人最终都将面临死亡。

然而，如果我们尽可能长地推迟疾病的发生，我们都将拥有更加强壮、更加健康的老年生活。

我们最终都不能回避死亡，但至少我们在离世之前不会遭受虚弱和痛苦的长期折磨。

7.这意味着未来的医学实践将更多地注重诊断或及早发现身体内部的变化。

如果在初期发现疾病，那时它还未形成并开始对身体进行侵害，治疗就会比较容易。

8.现代诊断始于19世纪90年代X射线的发现。

人们首次无需打开身体就能窥视体内器官。

但是，X射线只能发现大的原子微粒。

我们能清楚地看见骨头，但软组织显得不清楚。

除此之外，X射线能量很大，可能破坏身体甚至诱发癌症。

9.近年来，观察身体内部的方法得以改进。

我们能够运用比X射线危险性小得多的超声波。

还有一种被称为“核磁共振”的东西能根据原子对核磁区域的反应——甚至在软组织内——测出不同的原子。

它能显示X射线发现不了的东西，而且，它似乎对人体无害。

10.我们能够期盼，超声波、核磁共振或许还有其他技术将来可以在人体内任何东西开始变得异常之前就将其发现。

对少量血液的分析手段将得到改进，这样血液中任何反常的东西都能被筛选出来。

文献检索重点

·（名解）情报：在某一特定的时间，为解决某一特定的问题所需要的信息。

·（名解）文献：记录信息、知识的一切载体。

会判断一、二、三次文献·（名解）一次文献---原始文献。

以作者本人的工作和科研成果为依据而创作的原始论文。

（类型：多数的期刊文章、专利说明书、学位论文......）·（名解）二次文献---检索工具。

将分散无序的一、三次文献，按照一定的规则进行加工、整理、改编、组织、编辑成为系统有序、便于管理和查找利用一、三次文献的文献。

（类型：目录、索引、文摘、题录......文献检索---二次文献的使用！）·（名解）三次文献---综述文献。

针对某学科、专业或特定专题，在对大量相关一次文献进行分析、综合、评述等再度加工产生的文献。

（类型：综述、述评、述评、年鉴、手册、指南、进展、教科书、百科全书、科技专著......）·图书的特点：目的性强、稳定性好、系统性强、信息量大·期刊的特点：数量大、品种多、内容广；周期短、报道快、内容新；连续性、伸缩性。

·标准文献的特点：具技术先进、经济合理、内容科学的要求和指标，有明确适用范围和一定的法律约束力。

·文献检索的意义：1. 文献检索是科研工作的重要组成部分；2. 文献检索可缩短科研的过程；3. 文献检索可以减少重复性劳动、少走弯路。

·文献检索的途径：外表特征检索：文献标题、著者途径、序号途径、引文途径；内容特征检索：分类途径、主题途径、其他途径。

★文献检索的方法：1. 常用法：顺查（由远到近）、倒查（由近到远）；2. 追溯法；由点到面，以参考文献为基础3. 综合法：复合交替法、间隔交替法；4. 抽查法。

顺查法、倒查法、追溯法、抽查法有什么特点，区别在哪？各举个例子★文献特征（检索语言）：内部特征、外部特征内部特征：分类信息、关键词、主题词、分子式、化学结构…）外部特征：文献序号（专利号、标准号、合同号…）、文献标题、著者、单位、引文信息·数据库的类型：书目型数据库、事实型数据库、数值型数据库、全文型数据库。

science[1]

An Investigation of the Pathology and Pathogens Associated with Porcine Respiratory DiseaseComplex in DenmarkM.S.Hansen *,†,S.E.Pors *,H.E.Jensen *,V .Bille-Hansen †,M.Bisgaard *,E.M.Flachs ‡and O.L.Nielsen **Department of Veterinary Disease Biology,Faculty of Life Sciences (LIFE),University of Copenhagen,Ridebanevej 3,DK-1870Frederiksberg C,†Department of Veterinary Diagnostics and Research,The National Veterinary Institute,Technical University of Denmark (DTU),Bu ¨lowsvej 27,DK-1790Copenhagen V and ‡National Institute of PublicHealth,University of Southern Denmark,Oster Farimagsgade 5A,DK-1399Copenhagen K,DenmarkSummaryRespiratory infections are among the most important diseases of growing pigs.In order to elucidate the multifactorial aetiology of porcine respiratory disease complex (PRDC)in Denmark,lungs from 148ﬁnishing pigs with cranioventral bronchopneumonia (case group)and 60pigs without lung lesions (control group)were collected from abattoirs.The pathogens involved in PRDC and their interactions were identiﬁed and linked to the histopathological diagnosis.The lung samples were cultured for bacteria and tested by multiplex polymer-ase chain reaction for presence of swine inﬂuenza virus (type A),porcine reproductive and respiratory syndrome virus (both European and US type),porcine circovirus type 2(PCV2),porcine respiratory corona-virus,porcine cytomegalovirus,Mycoplasma hyopneumoniae and Mycoplasma hyorhinis .All cases had cranioventral lobular bronchopneumonia consistent with PRDC.There was a broad range of microscopical lesions and the cases were characterized as acute (n ¼10),subacute (n ¼24)or chronic (n ¼114)bronchopneumonia.Five bacterial species,ﬁve viruses and two Mycoplasma spp.were detected in different combinations.PCV2,M.hyopneumoniae ,M.hyorhinis and Pasteurella multocida were detected most frequently among the PRDC affected swine and the diversity and number of pathogens were higher in these animals compared with controls.No clear-cut associations were detected between pathogens and histological lesions or histopathological diagnoses.PRDC occurs more frequently than enzootic pneumonia among Danish ﬁnishing pigs and has complex and varied histopathology.Ó2010Elsevier Ltd.All rights reserved.Keywords:bronchopneumonia;histopathology;pig;porcine respiratory disease complex (PRDC)IntroductionRespiratory infections constitute some of the most im-portant diseases of growing pigs and result in substan-tial economic losses and reduced welfare (Sørensen et al.,2006).Porcine respiratory disease complex (PRDC)is a multifactorial disease of ﬁnishing pigs from 14to 22weeks of age (Thacker,2001;Kim et al.,2003).Morbidity ranges from 10%to 40%and mortality from 2%to 20%(Harding and Hal-bur,2002;Harms et al.,2002).Lesions are primarily located in the cranioventral parts of the lung,where consolidation,discoloration and failure of the lung tis-sue to collapse may be observed (Harms et al.,2002).Histopathology may vary according to the pathogens involved,but bronchopneumonia,sometimes in com-bination with interstitial pneumonia,is often reported (Harms et al.,2002;Kim et al.,2003).In the USA,the most commonly isolated pathogens are porcine repro-ductive and respiratory syndrome virus (PRRSV),swine inﬂuenza virus (SIV),porcine circovirus type 2(PCV2),Pasteurella multocida and MycoplasmaCorrespondence to:M.S.Hansen (e-mail:mesi@win.dtu.dk ).0021-9975/$-see front matter Ó2010Elsevier Ltd.All rights reserved .doi:10.1016/j.jcpa.2010.01.012p.Path.2010,Vol.143,120e 131Available online at /locate/jcpahyopneumoniae.Other important pathogens associated with PRDC are Streptococcus suis,Actinobacillus pleuro-pneumoniae and[Haemophilus]parasuis(Thacker, 2001;Harms et al.,2002;Choi et al.,2003).A study from1999showed that25%of Danishﬁnishing pigs had cranioventral bronchopneumonia(CBP)at slaughter(Christensen and Enoe,1999).Concurrent abattoir surveys in Switzerland and Belgium showed a similar prevalence(Grest et al.,1997;Maes et al., 2001),whereas earlier surveys revealed a higher prev-alence,from37%in Canada(Osborne et al.,1981), 45%in Australia(Davies et al.,1992)to78%in an-other Canadian study(Wilson et al.,1986).Abattoir surveys of porcine bronchopneumonia usually focus on the gross pathology and/or the microbiology, whereas the histopathology and microbiology are sel-dom linked.A survey of the pathogens involved in CBP in Danish pigs has not been performed for de-cades and since new respiratory viruses(i.e.PCV2, porcine respiratory coronavirus[PRCV],PRRSV and new strains of SIV)have been identiﬁed in recent years,a survey of respiratory pathogens in this species has become relevant.The aims of the present study were to elucidate the complexity of pathogens involved in PRDC and their interactions inﬁnishing pigs,and to associate these ﬁndings with the histopathological diagnosis,in order to broaden the understanding of the pathogenesis of porcine pneumonia.Materials and MethodsAnimalsDuring spring2006and winter2007,lungs,including tracheobronchial lymph nodes,from148ﬁnishing pigs with CBP(cases)and60pigs without gross lung lesions(controls)were collected from two Danish abattoirs in Zealand and Jutland.Cases of CBP were deﬁned as those with lesions affecting a minimum of three cranioventral lung lobes(i.e.the apical,cardiac and intermediate lobes;Sørensen et al.,2006).The gross lesions were of acute and chronic inﬂammation and included consolidation,swelling,hyperaemia, failure to collapse and/orﬁbrosis.The samples were cooled and processed(see below)within5h of sam-pling.Tracheobronchial lymph nodes were not ob-tained from two animals with CBP andﬁve control animals.Gross PathologyLungs and tracheobronchial lymph nodes were eval-uated macroscopically and the morphological pat-tern,type of exudate and estimated duration of the pulmonary lesions were recorded.A preliminary diagnosis was made based on these observations. The bronchopneumonia was of the lobular type as evidenced by sharp(lobular)delineation between lesional and non-lesional tissue.Acute lesions were oedematous,hyperaemic and swollen.Subacute lesions were those in which swelling and hyperaemia were no longer present,but in these cases there may still have been mild oedema and often marked exuda-tion into the bronchi.Chronic lesions were character-ized by atelectic,ﬁbrotic and grey-red lung tissue with dilation of exudate-ﬁlled bronchi.Lymph nodes were scored according to their size as normal(0),moderate enlargement(1)or marked enlargement(2). HistopathologyTissue samples were taken from lung lesions(cases), lung tissue of normal appearance from the dorsal sur-face of the right diaphragmatic lobe(all controls)and from the right apical lobe(20controls).The samples wereﬁxed in10%neutral buffered formalin for24h, embedded in parafﬁn wax,sectioned(3e5m m)and stained with haematoxylin and eosin(HE).Tissue sections for immunohistochemistry(IHC)were mounted on SuperFrostÒPlus slides(Mensel-gla ser, Braunschweig,Germany).Selected sections were stained by Masson’s trichrome and phosphotungstic acid haematoxylin to detectﬁbrin and collagen. IHC for cytokeratin(Soerensen et al.,2005)was ap-plied to conﬁrm the presence of epithelial hyperplasia, hyperplasia of type II pneumocytes and atelectasis. Sections were examined systematically by evalua-tion of the following structures in each section:bron-chi,bronchioles and bronchus-associated lymphoid tissue(BALT);alveolar ducts and alveoli,including alveolar septa;peribronchial,peribronchiolar and in-terlobular connective tissues;and pleura.BALT hy-perplasia was graded as follows(Ross,1999):(0) absent;(+)mild diffuse inﬁltration of lymphocytes in the peribronchial,peribronchiolar and perivascu-lar tissues including the lamina propria of the airways; (++)moderate increased diffuse inﬁltration of lym-phocytes and/or presence of a few lymphoid nodules; (+++)marked number of lymphoid nodules;or (++++)extensive number of lymphoid nodules af-fecting most of the lung section(Fig.1a e d).Alveolar exudates were classiﬁed according to Bochsler and Slauson(2002)as suppurative(neutrophils domi-nated),non-suppurative(mononuclear inﬂammatory cells dominated)or mixed(intermediate grades be-tween suppurative and non-suppurative;Fig.1e e g). Hyperplasia of type II pneumocytes was present when these cells lined more than3%of the alveolar surface area(Plopper and Adams,2006)(Fig.1h). Crowding of type II pneumocytes in close proximityPorcine Respiratory Disease Complex121Fig.1.Porcine lung tissue with different histological lesions found in cases of CBP.(a)Mild BALT hyperplasia (+)showing diffuseinﬁltration of lymphocytes (arrows)into the peribronchial,peribronchiolar and perivascular tissues including the lamina propria of the airways.B,bronchiole;V,blood vessel.HE.Bar,250m m.(b)Moderate BALT hyperplasia (++)showing greater diffuse in-ﬁltration of lymphocytes and/or the presence of a few lymphoid nodules (N).B,bronchiole.HE.Bar,250m m.(c)Marked BALT hyperplasia (+++)showing a considerable number of lymphoid nodules (N).B,bronchiole.HE.Bar,250m m.(d)Extensive BALT hyperplasia (++++)showing an extensive number of lymphoid nodules (N)affecting most of the lung section.A com-pressed bronchiole (B)can be seen.HE.Bar,250m m.(e)Suppurative alveolar exudates showing a cellular inﬁltrate dominated by neutrophils in acute suppurative bronchopneumonia (ASBP).HE.Bar,25m m.(f)Non-suppurative exudates showing a cellular inﬁltrate dominated by mononuclear inﬂammatory cells in chronic non-suppurative bronchopneumonia (CNBP).HE.Bar,25m m.122M.S.Hansen et al .to the interlobular connective tissue was not consid-ered a signiﬁcant lesion.Acute lesions were deﬁned as those with neutrophils as the dominant inﬂamma-tory cell type,extensive oedema and/orﬁbrin exuda-tion and absence of chronic signs.Chronic lesions were characterized byﬁbroplasias,BALT hyperpla-sia(of grade++to++++),hyperplasia of bron-chial or bronchiolar epithelium,presence of bronchiolar polyps and alveolar polyp-like structures with aﬁbrous core,hypertrophy of the smooth muscle layer around bronchioles and alveolar ducts,and cel-lular inﬁltrates primarily consisting of lymphocytes and plasma cells.Lesions that were not strictly acute or chronic(e.g.cellular inﬁltration dominated by neutrophils,combined with moderate BALT hyper-plasia as the only chronic lesion)were regarded as subacute.Thus,the extent of acute versus chronic signs determined the duration of the inﬂammatory re-sponse.The histopathological diagnosis was regarded as the deﬁnitive diagnosis.MicrobiologyBacterial Culture.Swabs from lung lesions(cases)and from macroscopically normal lung tissue of the right diaphragmatic lobe(controls)were taken under ster-ile conditions,plated on blood agar plates(blood agar base CM55;Oxoid,Basingstoke,UK;with5%calf blood)and incubated aerobically in a sealed plastic bag at37 C for18e24h.All samples were cross-inoc-ulated with a v-factor producing Acinetobacter calcoaece-ticus.Bacterial isolates were identiﬁed using standard methods for phenotypic characterization as previously described(Barrow and Feltham,1993).Growth of P. multocida was evaluated semi-quantitatively according to the number of bacterial colonies on the primary plates:(+)weak growth with1e25colonies,(++) dense growth with25e300colonies or(+++) marked growth with>300colonies.Streptococcus spp. were differentiated by pulsed-ﬁeld gel electrophoresis and strains representing different genotypes were identiﬁed by sequencing16S rRNA(Chadﬁeld et al., 2004).All v-factor-dependent cultures were also sub-jected to16S rRNA sequencing to obtain aﬁnal iden-tiﬁcation.Mixed cultures demonstrating less than25 colonies were regarded as contamination. Mycoplasma and Virus Detection by Polymerase Chain Reac-tion.Tissue samples from lung lesions(cases)and macroscopically normal lung tissue(controls)were frozen atÀ20 C and investigated by multiplex poly-merase chain reaction(PCR;PulmotestÒ,Landesla-bor Schleswig-Holstein,Food,Veterinary and Environmental Diagnostic Institute of Schleswig-Holstein,Neumu nster,Germany),according to the method described by Palzer et al.(2007).Pathogens detected by the multiplex PCR were:SIV(inﬂuenza A),PRRSV(both European and US type),PCV2, PRCV,porcine cytomegalovirus(PCMV),M.hyop-neumoniae and Mycoplasma hyorhinis.StatisticsData were analyzed statistically by Chi-square test or by Fisher’s exact test when a small sample size necessi-tated this.The analysis of number of pathogens in rela-tion to lesion duration was carried out as a Poisson regression.The degree of association was estimated by Spearman-rho factor.All analyses were done with SAS version9.1(SAS Institute,Inc.,Cary,North Car-olina)with signiﬁcance of P<0.05.Statistical analysis was not carried out on groups that included less than nine pigs and for this reason the results for PRRSV Eu-ropean and US types were pooled.When looking for as-sociations between pathogens or combination of pathogens and lesion duration,type of exudate or histo-pathological diagnosis,we tested against the remaining cases of CBP,excluding the control animals.ResultsGross PathologyThe gross lesions of all lungs in the case group(n¼148) were consistent with cranioventral,lobular broncho-pneumonia(Fig.2a).Mucopurulent,purulent or seromucous exudates were found in7%(11/148) acute,18%(26/148)subacute and75%(111/148) chronic cases of CBP,respectively.Focal or multifocal ﬁbrotic pleurisy of the diaphragm lobes,without any relation to the pneumonic lesions,was present in 36%(54/148)of these animals.Except for13% (8/60)of the control pigs,which had chronic focal pleurisy,none of the controls had gross lesions.No gross lesions were detected in the lymph nodes in ani-mals from either group.Lymph node scores for the cases of CBP were:score0,3%(4/146);score1,66% (96/146);and score2,32%(46/146)and for the con-trol pigs:score0,62%(34/55);score1,35%(19/55); and score2,4%(2/55).A signiﬁcant association was present between lymph node enlargement and CBP (P<0.001).When the lymph node scores were compared with the lesion duration(data not shown), no signiﬁcant association was found(P¼0.16).(g)Mixed exudates showing cellular inﬁltrate with both neutrophils and mononuclear cells in subacute mixed bronchopneumonia (SMBP).HE.Bar,25m m.(h)Marked hyperplasia of type II pneumocytes.More than50%of the alveolar surface is lined by type II pneumocytes.IHC.Bar,25m m.Porcine Respiratory Disease Complex123Fig.2.Porcine lung tissue with different lesions.(a)Gross appearance of chronic CBP.Inset shows lung tissue with a bronchial pattern ofpulmonary consolidation.(b)Suppurative bronchiolitis and concurrent epithelial hyperplasia (E).HE.Bar,25m m.(c)Oedem-atous ﬂooding of alveoli.HE.Bar,50m m.(d)Thickening of alveolar septa by collagenous (blue)tissue.Masson’s trichrome.Bar,50m m.(e)Alveolar polyp-like structures,P1with a ﬁbrinous core and P2with cellular inﬁltrate.Both are covered by type I and type II pneumocytes as shown by immunohistochemical labelling for cytokeratin expression.Bar,25m m.(f)Alveolar polyp-like structure (P)with a collagenous core (blue).Masson’s trichrome.Bar,15m m.(g)Focal necrotic encapsulated tissue with central mineralization (M).HE.Bar,100m m.(h)Mild thickening of alveolar septa from a pig in the control group.HE.Bar,50m m.124M.S.Hansen et al .HistopathologyBased on the histopathological examination,the lungs in the case group(n¼148)were divided into acute (7%,10/148),subacute(16%,24/148)or chronic (77%,114/148)cases of bronchopneumonia(BP). The histopathological diagnosis(deﬁnitive diagnosis) for all of the acute cases(n¼10)was suppurative BP (ASBP).The subacute cases(n¼24)were subdivided into suppurative BP(SSBP)(67%,16/24),mixed BP (SMBP)(25%,6/24)or non-suppurative BP(SNBP) (8%,2/24),and the chronic cases(n¼114)were sub-divided into suppurative BP(CSBP)(46%,52/114), mixed BP(CMBP)(32%,37/114)or non-suppura-tive BP(CNBP)(22%,25/114).The main histopath-ologicalﬁndings are summarized in Table1. Microscopical lesions were found in the alveoli of all lungs with CBP.The majority also had lesions af-fecting bronchioles and/or alveolar ducts,often to-gether with lesions in the interlobular connective tissue.Bronchitis and bronchiolitis were mainly sup-purative,with concurrent epithelial hyperplasia in the subacute and chronic cases(Fig.2b).In cases of bronchiolitis,destruction of the epithelial lining in the bronchioles was observed in17%(1/6),50% (4/8)and37%(11/30)of the acute,subacute and chronic cases of CBP,respectively.The mainﬁnding in the alveoli was inﬁltration of inﬂammatory cells (neutrophils,lymphocytes and plasma cells),reﬂect-ing the duration of the inﬂammatory response, whereas macrophages were identiﬁed at all stages. Oedematousﬂooding was a commonﬁnding in the al-veoli in acute,subacute and chronic cases of CBP, with the degree of oedema being more pronounced in acute stages(Fig.2c).Varying degrees of thicken-ing of the alveolar septa,mainly by collagenous tissue, were seen in25%(37/148),of cases of CBP(Fig.2d). Alveolar polyp-like structures were seen in acute, subacute and chronic bronchopneumonia,whereas bronchiolar polyps only occurred in subacute and chronic lesions.Alveolar polyp-like structures with aﬁbrinous core could be observed in both acute and chronic cases,whereas polyps consisting of collagen were not present in acute cases(Fig.2e,f).The major ﬁndings in the interlobular connective tissues were oedema,diffuse lymphocyte inﬁltration and/orﬁbro-plasia.Otherﬁndings included hypertrophy of the muscles around bronchioles and alveolar ducts and hyperplasia of type II pneumocytes.Occasionalﬁnd-ings were vasculitis,thrombosis and areas of necrosis with or without mineralization(Fig.2g).Not all combinations of these lesions were seen in the lung sections.The lungs from three animals,diag-nosed as acute(n¼1)or subacute(n¼2)according to gross pathology,were deﬁnitely diagnosed as chronic on the basis of histopathology.Microscopical lungTable1Histopathologicalﬁndings in the lungs from control animals and cases of CBPControl CBP*(n¼60)Acute(n¼10)Subacute(n¼24)Chronic(n¼114)n%n%n%n% Bronchitis123303121412 Bronchiolitis126608333026 Bronchiolar polyps0e0e282118 BALT hyperplasia†04168440281412+15256604172623++470e16675246+++0e0e0e1211++++0e0e28109 Alveolar oedema1288018756759 Fibrin exudation into alveoli0e550729109 Type II pneumocyte hyperplasia353307294035 Thickening of alveolar septa16271108332825 Alveolar polyp-like structures0e2209383026 Smooth-muscle hyperplasia231103133127 Interstitial oedema2377010423430 Interstitialﬁbroplasia231105213430 Necrotic foci0e0e1487*Cases of CBP were grouped as acute,subacute or chronic based on histological evaluation.†Hyperplasia of the BALT was scored as absent(0),mild(+),moderate(++),marked(+++)or extensive(++++).Porcine Respiratory Disease Complex125lesions were seen in50%(30/60)of the control animals and no difference was observed between the samples from the diaphragmatic and the cranioventral lobes. Theﬁndings in these animals mainly included focal or multifocal thickening of alveolar septa(Fig.2h) and/or mild BALT hyperplasia(Table1). MicrobiologyA total of12potential pathogens(ﬁve bacterial spe-cies,ﬁve viruses and two Mycoplasma spp.)were de-tected and these are listed in Table2.In general, the frequencies of the pathogens were higher in the case group compared with controls,except for PCMV,which was more frequent in the controls (though not signiﬁcant).PRCV was not detected in any of the pigs.Staphylococcus aureus,[H.]parasuis,A.pleuropneumoniae and SIV-A were only detected in one toﬁve animals.S.aureus,[H.]parasuis,A.pleuro-pneumoniae,PRRSV European and US type were only found in the cases of CBP.When comparing cases and controls according to pathogens(Table 2),all grades of P.multocida(P<0.001e P¼0.004), M.hyopneumoniae(P<0.001)and M.hyorhinis (P<0.001)were found more frequently in the cases of CBP.Furthermore,theﬁnding of mixed cultures and sterile samples was more frequent in the control group than in the case group(P<0.001).Signiﬁcant associations were observed between eight pairs of pathogens among the diseased animals and between two pathogens in the control group(Table3).A total of63different combinations of pathogens were present,many of which were only found in a sin-gle animal(n¼34;data not shown).Among the casesTable2Bacterial culture and multiplex PCR for viruses and MycoplasmaPigs with CBP(n¼148)Control animals(n¼60)P value*Acute Subacute ChronicASBP (n¼10)SSBP(n¼16)SMBP(n¼6)SNBP(n¼2)CSBP(n¼52)CMBP(n¼37)CNBP(n¼25)n%n%n%n%n%n%n%n%Bacterial cultureP.multocida†+0e2131170e484116‡240e0.004 ++2205‡313‡5015051025312120.004 +++77085011715031601849104012<0.001 S.suis0x e4252330e713822624610NS S.aureus0e0e0e1500e0e0e0e NS [H.]parasuis0e0e0e0e2425140e NS A.pleuropneumoniae0e0e0e0e120e0e0e NS Mixed culture2200e0e0e0e4110e2745<0.001 Sterile0e0e0e0e510384162542<0.001 Multiplex PCRPCV21010014886100210050963710024965693NS PRRSVEU type1103190e0e2413140e NS US type0e0e0e0e120e0e0e NS PCMV3303191170e15297196242643NS SIV-A0e0e0e0e0e251412NS M.hyopneumoniae10100159461001505198359524962137<0.001 M.hyorhinis9901381610021004179308117682235<0.001Numbers and percentage of positive animals are listed for the148pigs with CBP in relation to diagnosis.ASBP,acute suppurative bronchopneumonia(BP);SSBP,subacute suppurative BP;SMBP,subacute mixed BP;SNBP,subacute non-suppurative BP;CSBP,chronic suppurative BP;CNBP,chronic non-suppurative BP;CMBP,chronic mixed BP.PRRSV(EU type,European type;US type, North American type);SIV-A,swine inﬂuenza virus type A;NS,not signiﬁcant;PCV2,porcine circovirus type2;PCMV,porcine cytomegalo-virus.*P values for differences between cases and controls were calculated by either the Chi-square or Fischer’s exact test as appropriate.†Growth of P.multocida was graded as weak growth(+),dense growth(++)or marked growth(+++).‡The frequency of each pathogen detected in the diagnosis group was tested against the remaining cases of CBP by the Chi-square or Fischer’s exact test.Signiﬁcant associations are marked by‘‡’.126M.S.Hansen et al.of CBP and the control animals there were51and23 different combinations of pathogens,respectively. The10most frequent combinations are presented in Table4.Some combinations were seen in either dis-eased or healthy animals.The three most frequent combinations,only isolated from cases of CBP,were combinations1,6and10(Table4).Likewise,the two most frequent combinations,only seen among the control animals,were mixed culture and PCV2, and PCV2as a solitary pathogen.Associations between Microbiological and Histopathological FindingsWhen testing associations of selected histological le-sions(bronchiolar polyps,BALT hyperplasia,ﬁbrin exudation into alveoli,hyperplasia of type II pneu-mocytes,thickening of alveolar septa,alveolar polyp-like structures,necrotic foci)within the case group,and subsequently within lesion duration groups,to pathogens,signiﬁcant results were ob-tained for the following:in chronic cases with bron-chiolar polyps,P.multocida(+++)was isolated more frequently(P¼0.016);BALT hyperplasia (grade++to++++)was associated with PCMV in chronic cases(P<0.001);ﬁbrin exudation into alveoli was associated with the isolation of P.mul-tocida(++)(P¼0.018);thickening of alveolar septa was never seen when P.multocida(+)was isolated (P¼0.013).Furthermore,in78%(7/9)of cases with necrotic foci,P.multocida(+++)was present, although with an association of only borderline signif-icance(P¼0.062).No association between histologi-cal lesions and pathogens was found in the control group.Table2presents the frequencies of single patho-gens,divided according to the diagnosis groups. P.multocida was,as the only pathogen,isolated more frequently from the following groups:P.multocida (++)and SSBP(P¼0.054);P.multocida(++) and SMBP(P¼0.037);and P.multocida(+)and CNBP(P¼0.043).S.suis was not isolated from any case of ASBP(P¼0.021).Signiﬁcant associations were not seen when comparing single pathogens and type of exudate(suppurative,mixed and non-suppu-rative)or lesion duration(acute,subacute and chronic).In Fig.3the number of pathogens detected in each pig is listed for the lesion duration groups and the con-trol group.At least one pathogen was detected in all lung samples(cases and controls).Detection of a singleTable3Signiﬁcant associations between pairs of pathogens Associated pathogens P value*Spearman-rho factor Animals with CBP(n¼148)PCV2and P.multocida(+)†0.0170.067 PCV2and S.suis0.0210.088 PCV2and M.hyopneumoniae0.012À0.038 PCV2and PRRSV0.0130.048 PCV2and PCMV0.0250.104P.multocida(++)and M.hyorhinis0.0500.157S.suis and M.hyopneumoniae0.0220.097 PRRSV and M.hyopneumoniae0.0140.052 Control animals(n¼60)PCV2and S.suis0.0320.105*P values were tested by the Fischer’s exact test and the degree of association was calculated by the Spearman-rho factor-test.†Weak growth of P.multocida on the plate(+).Table4The10most frequent combinations of pathogensamong cases of CBP and control animalsCombination number12345678910 Mixed cultureÂP.multocida+ÂP.multocida++ÂP.multocida+++ÂÂÂS.suisÂPCMVÂÂÂPCV2ÂÂÂÂÂÂÂÂÂÂM.hyopneumoniaeÂÂÂÂÂÂÂM.hyorhinisÂÂÂÂÂÂFrequency of combination(n¼)*CBPAcute3e3†1e1e e e e Subacute4133e e e e e1 Chronic3398618e e34 Controls e4118e972eGrowth of P.multocida deﬁned as weak(+),dense(++)or marked (+++).*Number of animals with a given combination of pathogens.†Signiﬁcantassociation.Fig.3.The frequency of pathogen count detected in controlanimals(n¼60)and in animals with CBP of acute(n¼10),subacute(n¼24)or chronic(n¼114)type. Porcine Respiratory Disease Complex127pathogen(PCV2)occurred in seven animals,all from the control group.The majority of pigs in the control group had a signiﬁcantly lower number of pathogens, while cases of CBP had increased counts(P<0.001). Between lesion duration groups there was a tendency to a lower count in the chronic cases compared with acute and subacute cases;however,this difference was not signiﬁcant.When comparing the10most frequent combina-tions of pathogens and lesion duration groups(Table 4)the only signiﬁcant association was combination number3,which was seen more frequently in the acute cases(30%,3/10)(P¼0.044)than in the sub-acute(13%,3/24)and chronic cases(7%,8/114). There were no signiﬁcant associations when compar-ing these combinations of pathogens with types of ex-udate or histopathological diagnosis(data not shown).DiscussionPneumonia can be classiﬁed as embolic,broncho-pneumonia and interstitial or bronchointerstitial (Caswell and Williams,2007)based on the morpho-logical pattern observed in experimental studies and/or infections with single pathogens.The present study of naturally occurring pneumonia recorded a range of pneumonic lesions,but the predominant pattern was bronchopneumonia associated with thickening of the alveolar septa.In some animals chronic lesions were accompanied by acute lesions, which may represent the healing of acute pneumonic lesions or the presence of two different disease inci-dents.These cases of bronchopneumonia were also characterized microscopically according to the esti-mated duration of the disease process(i.e.as acute, subacute or chronic).Few previous studies have fo-cused on the histopathologicalﬁndings in porcine lungs with naturally occurring PRDC(Harms et al., 2002),whereas many studies describe naturally oc-curring gross lesions or the histopathology of experi-mental coinfections.The pigs examined by Harms et al.(2002)had clinical signs of respiratory disease and therefore the lesions observed in that study were more severe than in the pigs of the present investigation.The results of the present study show that the histo-pathology of PRDC is complex,as nearly all pulmo-nary reaction patterns can co-exist.Thickened alveolar septa were observed in pigs from both control and case groups,indicating that thisﬁnding is not en-tirely related to bronchopneumonia.This lesion may therefore be regarded as a pulmonary response to en-vironmental factors associated with swine production (e.g.dust and ammonia).Furthermore,thickening of alveolar septa was not associated with the presence of speciﬁc pathogens.Type II pneumocyte hyperplasia occurred more frequently in pigs with CBP compared with controls;however,the lesion did not appear to be associated with the duration of disease,since it was present in all diagnosis groups.In addition to the bronchiolar polyps in the pigs with pneumonic le-sions,there were also structures that resembled alveo-lar polyps,(i.e.they protruded from the epithelial surface in the alveoli and were covered by epithe-lium).Three different forms of alveolar polyp-like structures were identiﬁed(ﬁbrinous,cell-inﬁltratedﬁ-brinous and collagenous)and these probably repre-sented different stages of the same initial lesion. Alveolar polyp-like structures have not been described previously in pigs and their signiﬁcance is undetermined.Most authors deﬁne PRDC as a multifactorial re-spiratory disease involving several pathogens(Harms et al.,2002;Kim et al.,2003;Opriessnig et al.,2007; Fachinger et al.,2008),whereas Thacker(2006)spec-iﬁes PRDC as enzootic pneumonia(i.e.infection with Mycoplasma spp.and opportunistic bacteria)aggra-vated by respiratory viruses.Except for14animals, Mycoplasma spp.,bacteria and respiratory viruses were identiﬁed in all cases of CBP in the present study. This pathogen proﬁle,combined with the pathologi-calﬁndings,is in accordance with the diagnosis of PRDC,although it is not possible to determine the or-der of infection.Based on the pathogen combination,‘classical’enzootic pneumonia was only present inﬁve animals with CBP,which indicates that PRDC is more prevalent in Danishﬁnishing pigs compared with enzootic pneumonia.This probably corresponds to theﬁndings in other countries,where a mixture of Mycoplasma spp.,bacteria and viruses are identiﬁed in the majority of porcine pneumonias(Harms et al., 2002;Kim et al.,2003;Palzer et al.,2007).Twelve different pathogens were obtained from the lungs and the spectrum of pathogens correlated with observations made in other countries(Chiou et al., 2004;Palzer et al.,2008).The following potential pathogens(Thacker,2001;Liljegren et al.,2003) were only present in the case group:S.aureus,[H.]par-asuis,A.pleuropneumonia and PRRSV(European and US type).Therefore,these agents might represent more aggressive pathogens in cases of PRDC,al-though the difference in frequency between cases and controls was not signiﬁcant.The diversity and number of pathogens were higher among the diseased animals compared with the control group,supporting the deﬁnition of PRDC as a multifactorial disease (Harms et al.,2002),which should be considered when diagnosing and treating cases of PRDC and in prophylactic strategies.The observed tendency128M.S.Hansen et al.。

现代大学英语精读1unit6课文翻译

现代大学英语精读1unit6课文翻译第六单元青香蕉1.尽管这种事情在任何地方都可能发生，但我与青香蕉的邂逅却源自于巴西腹地一条险峻的山路上。

我那老式吉普车正吃力地穿过景色优美的乡村，这时，水箱突然漏水了，而离我最近的汽车修理站也还要十英里。

发动机过热迫使我在临近的村庄停了下来。

村里有一个小商店和分布在四处的几座房子。

有村民围过来看，三股细细的热水柱从水箱外壳上的小孔喷出来。

“这容易解决，”一个人说到。

他让一个小男孩跑去拿些青香蕉来。

这个人还拍了拍我的肩膀，安慰我问题会解决的。

“青香蕉。

”他笑了，其余的人都这么说着。

2.我和他们闲聊起来，心里却一直在想他们用这青香蕉怎么能修补好水箱。

毫无疑问，提问会暴露我的无知，因此我开始赞叹眼前美丽的乡村景色。

耸立在我们周围巨大的岩石群，很像里约热内卢著名的糖面包山。

“看见那边那块高高的岩石了吗？”那人指着一块特别高而且细长的黑色石柱问我，“那块岩石标志着世界的中心。

”3.我看着他，想知道他是否在和我开玩笑，但他却表情严肃，反过来认真地审视着我，似乎想确定我是否领会了他那句话的深刻含义。

这种情况要求我必须表现出认同。

他点头说：“绝对是中心。

这儿的人都知道。

”4.这时，小男孩抱着青香蕉回来了。

那个男子把其中一根掰成两半，将其断口处按在水箱的外壳上。

香蕉遇到炙热的金属融成了胶，立刻就堵住了漏洞。

面对如此情景，我惊呆了，我当时的表情一定是傻傻的，所有的人都笑了起来。

他们把我的水箱装满水，又让我带上一些香蕉，以防沿途中水箱再出问题。

路上，我又用了一次青香蕉，一个小时后，我开着车到达了目的地。

当地的一修理工笑着问我：“谁教你用青香蕉的？”我告诉了他那个村子的名字。

“他们有没有指给你看标志世界中心的那块岩石?”他问道。

我告诉他，他们指给我看了。

“我祖父就是那儿的人，”他说，“那的确是中心。

一直以来这儿的人都知道。

”5.作为美国教育的产物，除了把青香蕉当作还没长熟的水果，我从来就没注意过它。

全新版大学英语综合教程4课文原文及翻译

dluohS .noisiced laicurc a htiw decaf won saw eH .yrotciv evisiced on now d ah noelopaN .yrotirretnaissuR otni rehtraf taerter ot elba niaga erew snaissuR eht teY .edis hcae no daed dnasuohtnet revo tfel taht elttab a ni ksnelomS ta deg agne seim ra naissuR dna hcnerF eht tsuguA nI 5 。

来下顿停而慢缓输运草粮于由快很入直驱长的它但舍不追紧军大。

居民和稼庄毁焚途沿撤东路一们他反相。

抗抵起奋不并人国俄是的惊吃他令。

生发有没迟迟胜速决速的着盼期仑破拿。

国俄入进河曼涅过渡军大的仑破拿久不.senilylppus gnivom - wols yb nwod deggob emaceb noos hcram ecn avda sti tub dewollof ym rA dnarGehT .tnew yeht sa semoh dna sporc rieht gninrub drawtsae detaerter yeht daetsnI .thgif dna dnatsot desufer sn aissuR eht esirprus sih oT .deneppah reven detcepxe noelopaN taht yrotciv evisicedkciuq ehT .aissuR otni reviR nameN eht desso rc ymra snoelopaN sdrawretfa yltrohS 4 。

国俄下攻内期星个5在要言预信自满充功成到马对仑破拿。

军大为称被队军支这。

良精备装强力战作练训好良过受兵士些这。

光纤通信简介翻译级英文原文

�处好列下有输传的号信电用使�言而用应信通的宽带低对相和离距短于对。反相好正线输传的号信电输传和这�扰干的讯串生产会不也行并纤光条数使即时输传离距长在是点优个一另的纤光�缆光成换求要被都缆电多很。力能息信带携的高较有身本且输传行并率功�扰干号信他其和流电的上地有没它�耗损的小常非有纤光是点优的要主最。离距输传的长较有以可缆电于对相者或度宽带频的高较有求要常通纤光择选统系为 �衡权行进题问点几就要需输传行进缆铜用利是还输传纤光用利是择选在
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高考英语一轮复习UNIT1SCIENCEANDSCIENTISTS课件新人教版选择性必修第二册

6．He read many professional books, which laid a _s_o_li_d_ (坚实的) foundation for his career.
7．My main reason for _s_u_b_s_c_ri_b_i_n_g_ (订阅) to New Scientist is to keep abreast of advances in science.
8．Taking adventures to admire nature's r_a_w_ (未经处理的) beauty has always been part of human desire.
9．Children have so far been largely spared from the most _s_e_v_er_e_ (十分严重的) symptoms of the disease.
10．Such a development represents a gradual _s_h_i_ft_ (转换) from the old view of many that face masks were only needed by medical staff and the sick.
Ⅱ.词汇派生 1．The baby had an ear __in_f_e_c_ti_o_n_ (infect). 2．I have times when I feel _f_r_u_s_tr_a_te_d__ (frustrate) and wish I could get away. 3．Fedora, leader of the study, is also excited about these new _f_in_d_i_n_g_s_ (find). 4．I have to say in her __d_e_fe_n_s_e_/d_e_f_e_n_c_e_ (defend) that she knew nothing about it beforehand. 5．The __th_i_n_k_e_r,__who developed stronger critical _t_h_in_k_i_n_g_ skills, refused to accept the idea without a second _t_h_o_u_g_h_t ．(think)

SCI 知识(阿牛upload)

SCI知识SCI是美国《科学引文索引》的英文简称，其全称为：Sci ence Citation Index,，创刊于1961年，它是根据现代情报学家加菲尔德(Engene Garfield) 19 5 3年提出的引文思想而创立的。

时至今日加菲尔德仍是SCI主编之一。

SCI是由ISI（Institute for Sci entific Information Inc.）美国科学情报所出版。

现为双月刊。

ISI除了出版SCI外，还有联机型数据库SCI SEARCH。

ISTP （Index to Sci entific ＆Technical Proceeding）也由其出版。

SCI是一部国际性的检索刊物，包括有：自然科学、生物、医学、农业、技术和行为科学等，主要侧重基础科学。

所选用的刊物来源于94个类、40多个国家、SO多种文字，这些国家主要有美国、英国、荷兰、德国、俄罗斯、法国、日本、加拿大等，也收录一定数量的中国刊物。

SCI选择期刊比较科学，它运用引文数据分析和同行评估相结合的方法，充分考虑了期刊的学术价值，在选用的 3 400余种期刊里包含了国际上较为重要的期刊。

它所择取的80万条论文，可以说是集各学科之精萃。

因而，它成为国际公认的反映基础学科研究水准的代表性工具。

并将其收录的科技论文数量的多寡，看做是一个国家的基础科学研究水平及其科技实力指标之一。

SCI检索系统历来成为世界学术界密切注视的中心，争相角逐的焦点，世界公认的文献统计源。

然而，SCI就其本身而言，最重要的功能是帮助科技人员获取最需要的文献信息。

这也是编辑该部索引的主要意图。

SCI最大的优点是引文功能，在这里读者能很快地了解到某一作者的某篇论文是否被他人引用过，通过引文次数可以了解某一学科的发展过程。

另外，使用SCI还可以了解到科学技术发展的最新信息，如：有没有关于某一课题的评论？某一理论有没有被证实，某方面的工作有没有被扩展，某一方法有没有被改善，某一提法是否成立，某一概念是否具有创新性等等。

sci 引用原句

sci 引用原句标题：科学家发现地球上最古老的化石1. 标题：科学家在澳大利亚发现了一种距今约38亿年的古老微生物的化石引用句：The scientists have discovered fossilized microorganisms in Australia that date back approximately 3.8 billion years.2. 标题：科学家在南非发现了一种距今约37亿年的古老微生物的化石引用句：Researchers have found fossilized microorganisms in South Africa that date back approximately 3.7 billion years.3. 标题：地质学家在加拿大发现了一种距今约34亿年的古老藻类化石引用句：Geologists have discovered fossilized algae in Canada that date back approximately 3.4 billion years.4. 标题：古生物学家在中国发现了一种距今约32亿年的古老生物的化石引用句：Paleontologists have found fossilized organisms in China that date back approximately 3.2 billion years.5. 标题：科学家在格陵兰岛发现了一种距今约31亿年的古老微生物的化石引用句：Scientists have discovered fossilized microorganisms on Greenland that date back approximately 3.1 billion years.6. 标题：地质学家在阿拉伯联合酋长国发现了一种距今约29亿年的古老藻类化石引用句：Geologists have discovered fossilized algae in the United Arab Emirates that date back approximately 2.9 billion years.7. 标题：古生物学家在印度发现了一种距今约27亿年的古老生物的化石引用句：Paleontologists have found fossilized organisms in India that date back approximately 2.7 billion years.8. 标题：科学家在俄罗斯发现了一种距今约26亿年的古老微生物的化石引用句：Scientists have discovered fossilized microorganisms in Russia that date back approximately 2.6 billion years.9. 标题：地质学家在美国发现了一种距今约24亿年的古老藻类化石引用句：Geologists have discovered fossilized algae in the United States that date back approximately 2.4 billion years.10. 标题：古生物学家在澳大利亚发现了一种距今约22亿年的古老生物的化石引用句：Paleontologists have found fossilized organisms in Australia that date back approximately 2.2 billion years.。

6月英语六级深度阅读第原文

6月英语六级深度阅读第原文2012年6月英语六级深度阅读第二篇原文For most of the 20th century, Asia asked itself what it could learn from the modern, innovatingWest. Now the question must be reversed. What can the West's overly indebted andsluggish(经济滞涨的) nationslearn from a flourishing Asia?Just a few decades ago, Asia's two giants were stagnating(停滞不前) under faulty economicideologies. However, once China began embracing free—market reforms in the 1980s, followedby India in the 1990s, both countries achieved rapid growth. Crucially, as they opened up theirmarkets, they balanced market economy with sensible government direction. As the Indianeconomist Amartya Sen has wisely said, "The invisible hand of the market has often reliedheavily on the visible hand of government.”Contrast this middle path with America and Europe, which have each gone ideologically over—board in their own ways. Since the 1980s, America has been increasingly clinging to theideology of uncontrolled free markets and dismissing the role of government—followingRonald Regan's idea that "government is not the solution to our problem; government is theproblem. "of course, when the markets came crashing down in 2007, it was decisivegovernment intervention that saved the day. Despite this fact, many Americans are stillstrongly opposed to "big government."If Americans could only free themselves from their antigovernment doctrine, they would beginto see that the U.S.'s problems are not insoluble. A few sensible federal measures could putthe country back on the right path. A simple consumption tax of, say, 5 percent would make asignificant dent in the country's huge government deficit without damaging productivity. Asmall gasoline tax would help wean America from its dependence on oil imports and createincentives forgreen energy development. In the same way, a significant reduction of wastefulagricultural subsidies and other earmarks could also lower the deficit. But in order to capitalizeon these common—sense solutions, Americans will have to put aside their own attachment tothe rhetoric of smaller government and less regulation. American politicians will have todevelop the courage to follow what is taught in all American public—policy schools: that thereare good taxes and bad taxes. Asian countries have embraced this wisdom, and have builtsound long—term fiscal policies as a result.Meanwhile, Europe has fallen prey to a differentideological trap: the belief that European governments would always have infinite resourcesand could continue borrowing as if there were no tomorrow. Unlike the Americans, who felt thatthe markets knew best, the Europeans failed to anticipate how the markets would react totheir incessant borrowing. Today, the EU is in firefighting mode to stave off sovereigncollapse. In concert with the IMF, it has created a $580 billion fund to bail out Europe'stroubled economies. This will buy the EU time, but it will not solve the bloc's larger problem.57. What has contributed to the rapid economic growth in China and India?A) Copying western—style economic behaviorB) Heavy reliance on the hand of governmentC) Timely reform of government at all levelsD) Free market plus government intervention58. What does Ronald Reagan mean by saying "government is the problem" (line4,para.3)A) many social evils are caused by wrong government policiesB)many social problems arise from government's inefficiency.C)government action is key to solving economic problemsD)government regulation hinders economic development59. What stopped the American economy from collapsing in 2007?A) self—regulatory repair mechanisms of the free marketB) Cooperation between the government and businessesC) Abandonment of big government by the publicD) Effective measures adopted by the government60. What is the author's suggestion to the American public in face of the public governmentdeficit?A) They urge the government to revise its existing public policiesB) They develop green energy to avoid dependence on oil importC) They give up the idea of smaller government and less regulationD) They put up with the inevitable sharp increase of different taxes61. What's the problem with the European Union?A) Conservative ideologyB) Shrinking marketC) Lack of resourcesD)Excessive borrowing。

Superradiance and Instability of Black Holes

a rXiv:0711.4184v2[he p-th]18D ec27KEK-Cosmo-1Superradiance and Instability of Black Holes Hideo Kodama ∗)Cosmophysics Group,IPNS,KEK and the Graduate University of Advanced Studies,1-1Oho,Tsukuba 305-0801,Japan Abstract We discuss the relation between the superradiance phenomenon and the insta-bility of rotating black holes in higher dimensions.In particular,we point out that the superradiant instability of a massless scalar ﬁeld around a simply rotating Kerr-adS black hole implies the gravitational instability of that black hole for tensor-type perturbations.§1.IntroductionThe stability of black holes has a crucial importance when we study their formation and fate in Nature.It also has an intimate relation with the cosmic censorship hypothesis.For these reasons,this problem has been studied for a long time,and uniqueness and perturbative stability were established for most asymptoticallyﬂat black holes in the four-dimensional Einstein-Maxwell system except for the Kerr-Newman black hole.1),2)When we go beyond this classical system,we encounter various new situations.One such extension is to consider systems containing other types of matter.Very interesting examples are the Einstein-Skyrme system and the Einstein-Yang-Mills system.These systems have three families of static asymptoticallyﬂat spherically symmetric solutions;a soliton family, a hairy black hole family and the vacuum one.These all families of solutions ware shown to be stable numerically for the Einstein-Skyrme system while for the EYM system,the colored black holes and the soliton solutions were shown to be unstable(see Ref.3)for review). Hence,in the latter case,the uniqueness theorem holds practically.Another extension motivated by recent progresses in uniﬁed theories is to consider higher-dimensional black holes.In the static AF Einstein-Maxwell system,the uniqueness theorem still holds in higher dimensions.Further,in the vacuum case,the Schwarzschild-Tangherlini solution was shown to be stable4)by using the extension of the Regge-Wheeler and Zerilli equations to higher dimensions,5)although the stability of the charged static black hole was proved only for D=5analytically6)and for6≤D≤11numerically.7)If we consider non-asymptoticallyﬂat systems,however,the situation changes.The most notorious is the Gregory-Laﬂamme instability of black string and branes.8)–10)A Gregory-Laﬂamme type instability is also predicted to occur around the rotation axis of rapidly rotating Myers-Perry black holes11)(cf.Ref.12))Non-vanishing cosmological constant also introduces subtleties.In four dimensions(D= 4),static adS/dS black holes and their charged extensions can be shown to be perturbatively stable.4),6)The perturbative stability can be also proved for static dS black holes in D=5 and6analytically4)and7≤D≤11numerically7)for the neutral case and in D=5 analytically6)and6≤D≤11numerically7)for the charged case.This suggests that the introduction of a positive cosmological constant does not aﬀect the stability property of a black hole.In contrast,the stability property of adS black holes is not certain in D≥5, except for topological black holes with zero or negative mass13)Finally,we encounter surprising new and rich phenomena when we study rotating black holes in higher dimensions.In particular,the discoveries of various black ring solutions14)has revealed the fact that rotating black holes are far from unique inﬁve dimensions and possiblyin other higher dimensions.This fact should,however,be taken with care because only stable solutions will be realised in Nature,at least asﬁnal states.In fact,many people seem to suspect that black ring solutions would suﬀer from a Gregory-Laﬂamme type instability.Unfortunately,however,no exact analysis of perturbative stability has been done for most rotating black objects in higher dimensions so far.One exception is the Kerr-adS black hole.In four andﬁve dimensions,this black hole were conjectured to be stable for slow rotation|a|ℓ<r2h and unstable for rapid rotation violating this condition,15)where a is the angular momentum parameter,r h is the horizon radius andℓis the curvature radius of the asymptotic adS spacetime.In four dimensions,this conjecture was proved to hold numerical in some limiting cases by Cardoso,Dias and Yoshida.16),17)This instability is understood to be caused by superradiance.As is well-known,the superradiance is the phenomenon that the amplitude of a bosonicﬁeld wave incidental to a Kerr black hole is ampliﬁed after reﬂection for some range of frequencies.18)Press and Teukolsky19)pointed out that this superradiance provokes an instability if a Kerr black hole is surrounded by a reﬂective mirror wall.20),21)Later on,it was suggested that this superradiance instability would occur even without such a wall if we consider a massive scalarﬁeld,because the barrier of its eﬀective potential plays the role of the mirror,22) although the growth rate of this instability is too small to be eﬀective in the real world except for the black hole of the Planck mass scale.23)–26)This mechanics was used to explain the instability of aﬁve-dimensional spinning black string solution27),28)and to predict the instability of large doubly rotating black rings.29)The most peculiar feature of asymptotically adS spacetimes is its global non-hyperbolicity. This is caused by the fact that the spatial inﬁnity is causally at aﬁnite distance and forms a time-like boundary.Due to this feature,a scalarﬁeld around a rotating black hole in an adS spacetime may suﬀer from a superradiance instability even theﬁeld is massless.This is the instability pointed as by Hawking and Reall.In this paper,we show that we can utilise this argument on the superradiance instability of a massless scalarﬁeld to study the gravitational stability of Kerr-adS black holes.§2.Superradiance of Asymptotically Flat Black HolesWeﬁrst outline the derivation of the superradiance condition for asymptoticallyﬂat rotating black holes in a form that does not depend on spacetime dimension or horizon topology.Fig.1.Global structure of DOC of an asymptoticallyﬂat black hole2.1.Symmetry and Asymptotic Structure of SpacetimeFor an asymptoticallyﬂat black hole spacetime,the DOC M is simply connected and globally hyperbolic,and its boundary consists of four components corresponding to the future and past inﬁnities and the future and past horizons:30)–32)∂M=H+∪H−∪I+∪I−(see Fig.1).In the present paper,we only consider a stationary rotating black hole with analytic metric.Then,from the rigidity theorem,33)there exist commuting rotational Killing vectors ηi(i=1,···,N)with N≥1in addition to the time translation Killing vectorξ.Let (y p)=(t,ϕi)be coordinates in orbits of(ξp)=(ξ,ηi)such thatξp y q=δq p,and x a be coordinates labeling orbits such thatξp x a=0.Then,the spacetime metric can be writtends2=g pq(x)χpχq+q ab(x)dx a dx b,(2.1) whereχp is a1-form written asχp=dy p+A p a(x)dx a.At inﬁnity,this metric approaches the Minkowski spacetime and has the asymptotic formds2=−f(r)dt2+dr2r D−2 ,(2.2)where D is the spacetime dimension,dΩ2n is the metric of unit Euclidean n-sphere S n,andf(r)is f(r)=1−2M/r D−3.In contrast,the spacetime is largely deformed due to rotation near the horizon.In higherdimensions,the rotation is characterised by the(multi-component)angular velocityΩi h ofthe horizon,which is deﬁned through the expression k=ξ+Ωi hηi for each null geodesicgenerator k of the horizon H+∪H−in terms of the Killing vectors.This angular velocity can be determined from the metric in the following way.First,because k is a null vector,theangular velocity of the horizonΩi h satisﬁes g tt+2g tiΩi h+g ijΩi hΩjh=0.Since k is the uniquenull direction in the(N+1)-plane spanned byξandηi,this equation must have a singlesolution for(Ωi h)as a vector.Hence,Ωi h can be expressed asΩi h=Ω|i horizon(Ωi:=−g ij g tj), and the horizon location is determined by¯∆:=−g tt+g ij g ti g tj=0.In order to deﬁne a regular coordinate system around the horizon,we introduce a new variable˜ϕi that is constant along the null geodesic generators:k˜ϕi=0,ηj˜ϕi=δi j.These conditions determine˜ϕi as˜ϕi=ϕi−Ωi h t,upto a constant independent of t andϕi.By introducing an appropriate function r which is equal to r h on the horizon,we can rewrite the metric near the horizon asΣ2∆ds2=−dr2+q AB(r,z)dz A dz B,(2.3)∆where˜χi=d˜ϕi+A i−Ωi h A t,∆is a function only of r,andΣ2andΓare regular functions around the horizon such that¯∆=Σ2∆/Γand g rr=Σ2/∆.We can show thatΓis equal to a constantΓ0on the horizon from the zeroth-law of black holes because it is related to the∆′(r h).Then,in terms of the coordinates surface gravityκof the black hole by2κ=Γ−1/2(u+,˜ϕ,r,z i)where u+=t+r∗with r∗:= rΓ1/20dr/∆,we can put the metric in a form that is regular around the future horizon.Similarly,if we use u−=t−r∗in place of u+,we obtain a regular coordinate system around the past horizon.2.2.ScalarﬁeldsLet us consider a massless free scalarﬁeld with charge q that satisﬁes the Klein-Gordon equation DµDµφ=0with Dµ=∂µ−iqAµ.For any complex solutionsφ1andφ2,the Klein-Gordon product deﬁned byI(φ1,φ2):=−i Σ ¯φ1Dµφ2−(¯Dµ¯φ1)φ2 dΣµ(2.4) is independent of the Cauchy surfaceΣin a global hyperbolic domain of the spacetime. 2.2.1.Asymptotic behavior at inﬁnityFrom the isometry,we can expand the massless scalarﬁeldφinto eigenmodes with respect toξandηasφ=ˆφ(r,z)e−iωt+im·ϕ,where m·ϕ=m iϕi with m i being a set of integers.The amplitude of each eigenmodeˆφbehaves at inﬁnity asˆφ≈12.2.2.Boundary condition at the horizonNear the future(or past)horizon,the coordinates(u+,˜ϕi,r,z A)are regular.In terms of these coordinates,the eigenmode is writtenφ=ˆφ(r,z)e iω∗r∗e−iω∗u++im·˜ϕ,(2.6)whereω∗=ω−m iΩi h.Here,from the asymptotic behavior of the equation forˆφnear the horizon,ˆφbehaves asˆφ(r,z)≈C(z)e−iω∗r∗+D(z)e+iω∗r∗near the horizon.This becomes purely ingoing at horizon if D=0andˆφ(r,z)≈C(z)e−iω∗r∗.(2.7)2.2.3.SuperradianceLet us consider Cauchy surfacesΣthat extend to spatial inﬁnity and have the common inner boundary at the bifurcating n-manifold H+∩H−.If we take the past limit of such surfaces,they approachesΣ−=H−∪I−.Hence,assuming that there exists no bounded state around the black hole,the KG product in this limit can be simply given by the contribution from I−,I I−=i dv S n dΩn lim r→∞r n(¯φ↔∂vφ)= m dω4πω |Aω,m|2 ,(2.8) where v=t+r∗and |A|2 :=2π S n/S1d n−1z√e−iω(t−r∗)at I+,r n/2(2.9)Ce−iω∗u++im·˜ϕat H+.The contribution from I+to the KG product,I I+,is given by replacing A by B in the above expression forΣ−.To obtain IΣ,we have to add to this the contribution from H++given byI H+=i du+ B d˜ϕd n−1z√ρq|C|2,andΦh is the electric potential of the horizon with respect to inﬁnity.Since the KG product is independent of the choice of a Cauchy surface with theﬁxed boundary,we obtain I I−=I I++I H+,which generally impliesω |Aω,m|2 =ω |Bω,m|2 +(ω∗−qΦh) |Cω,m|2 B(2.11) Hence,the transmission and reﬂection coeﬃcients for the free massless scalarﬁeld are givenby1=Tω,m+Rω,m;Tω,m=ω∗−qΦh|Aω,m|2 ,Rω,m=|Bω,m|2perbolic and its boundary consist of the past and future horizons and the spatial inﬁnity:∂M=H+∪H−∪I.Second,although the spacetime can have the same symmetry struc-ture as the asymptoticallyﬂat black holes,the time translation Killing vectorξis not unique in the asymptotically adS case,in contrast to the AF case.This is because the norm of the static time-like Killing∂t of the exact adS spacetime diverges in proportion to r2at inﬁnity, while the norm ofηi behaves in the same way.Hence,in a rotational spacetime,any linear combinationξ+c iηi has the equal right as the Killing vector to deﬁne the time translation. This freedom introduces an ambiguity in the deﬁnition of the angular velocity of a black hole given above.Apart from this point,the structure around horizon for an adS black hole is the same as that for an AF black hole.3.2.Superradiance?The features of an asymptotically adS black hole spacetime pointed out above make the argument of superradiance quite delicate.First,if we consider a hypersurfaceΣshown by the dashed line in Fig.2and take the limit such thatΣapproach the boundary of the DOC, theﬂux conservation law for a scalarﬁeld can be writtenI H++I I=I H−=0.(3.1)In order to estimate I I,we need to know the asymptotic behaviour of theﬁeld.For a massless scalarﬁeld satisfying the KG equation,the leading part of the asymptotic behaviour does not depend on the properties of a black hole at the center and is the same as that in the exact adS spacetime.Forφ∝e−iωt,it is given byφ≈E0+E1/r D−1.Hence,if we require that theﬁeld conﬁguration has aﬁnite energy,we have to select the boundary condition φ∼1/r D−1at r∼∞.For this boundary condition,we haveI I=−i dt d D−2Ωlim r→∞r D−2(1+r2/ℓ2)¯φ↔∂rφ=0.(3.2) Hence,we are left with the funny condition(ω−mΩh−qΦ) |C2ω,m| B/T N=0.(3.3) Clearly,the condition obtained above does not seem to be giving any information on superradiance.In fact,if we repeat the same argument for a rotating black hole inside a mirror box,we would obtain the same result.In this black hole bomb case,however,we know that instability occurs for modes with frequencies satisfying the standard superradiance condition(2.13).21)Since theﬂux conservation law also holds in this case with instability, what is wrong with the above argument is the neglect of the contribution from the volumeintegral atﬁnite distances.In the black hole bomb case,the energy extracted from the black hole is deposited in a region between the black hole and the mirror,and the contribution to the KG product from that region grows with instability.In the adS black hole case,a similar phenomenon may happen.3.3.Globally Timelike Killing VectorHawking and Reall pointed out that the freedom in the choice of a timelike Killing vector has a very signiﬁcant implication to the stability problem of an adS-Kerr black hole and the relevance of superradiance to it.Their argument goes as follows.First,if there is a Killing vectorξthat is timelike everywhere outside the horizon,one can construct the conserved energy integral∂t Σ(t)dΣnµξνTµν=0,(3.4) where nµis the normal vector to the Cauchy surfaceΣ(t).Here,if the matter satisﬁes the dominant energy condition,andξis timelike everywhere,the integrant nµξνTµνis non-negative everywhere.Hence,any instability of the exponential growth type cannot occur.In a stationary black hole spacetime,any Killing vector is spacelike or null on horizon because all Killing vectors are tangential to the horizon.Hence,a Killing vector that is timelike outside the horizon,if it exists,should be identical to the Killing vector k that is parallel to the null geodesic generator of the horizon.Therefore,the problem is when k is timelike everywhere outside the horizon.For example,the Kerr-adS solution in arbitrary dimensions was recently found by Gib-bons,L¨u,Page and Pope.34)This solution is parametrised by the mass M,the multi-component angular momentum a1,···,a N′and the cosmological constant parameterλ=−1/ℓ2,where N′=[(D+1)/2]−1.It is easy to show that k is timelike at inﬁnity if and only ifℓ2Ωi h2≤1⇔ℓ2a2i≤r4h(i=1,···,N′).(3.5) However,it is in general diﬃcult to see whether k·k<0everywhere outside the horizon under this condition,Some exceptions are the case of theﬁve-dimensional Kerr-adS solution discussed by Hawking and Reall15)and the case in which the angular momentum components vanishes except for one component,say a1=a,a2=···=a N′=0.At least in these special cases, matterﬁelds satisfying the dominant energy condition are stable if the condition(3.5)holds, from the above argument by Hawking and Reall.Of course,this does not immediately implies that the black hole is gravitationally stable as well.§4.Instability of AdS-Kerr Black HolesA reduction of the Einstein equations for gravitational perturbations to a Teukolsky type equation is possible for an adS-Kerr black hole in four dimensions.35)With the help of this formulation,it was shown that the four-dimensional adS-Kerr black holes are really unstable at least in the limit r h/ℓ≪1for modes satisfying the superradiance condition ω−mΩh<0.17)Although it is not imposed explicitly,the conditionℓΩh>1is practically satisﬁed under the superradiance condition because the real part of the eigen frequencyωfor unstable modes are discrete and its minimum value is approximately(m+2)/ℓfor m>0.In dimensions greater than4,however,no such reduction is available for gravitational perturbations of adS-Kerr black holes.One exception is the simply rotating black hole with a1=a,a2=···=a N′=0.The metric for such a black hole has U(1)×SO(n+1)symmetry with n=D−4in addition to the time translation invariance and can be written asds2=g ab(x)dx a dx b+S(x)2dΩ2n,(4.1)where dΩ2n is the metric of the Euclidean sphere S n.Hence,we can classify perturbations into scalar,vector and tensor types according to their transformation properties as tensors on S n.36)In particular,for n≥3,i.e.,for D≥7,non-trivial tensor perturbations can exist, and the expansion coeﬃcient H T of their amplitudes with respect to the tensor harmonics satisﬁes the hyperbolic equation on the four-dimensional spacetime with the metric ds24= g ab(x)dx a dx b,2H T−n S2H T=0,(4.2) where D a is the covariant derivative with respect to the metric ds24,2=D a D a and l is an integer greater than1labeling the tensor harmonics.A very interesting feature of this equation is that it is identical to the equation for spherical harmonic expansion coeﬃcients of a massless scalarﬁeld in the same spacetime. Thus,the stability issue of the black hole for tensor perturbations can be reduced to the same issue for a free massless scalarﬁeld.In particular,from Hawking and Reall’s argument,we can immediately conclude that the black hole is stable for tensor perturbations ifℓ2a2≤r4h.We can directly check this by writing the energy integral explicitly.In the coordinates in which the metric can be writtends2=−∆rCsin2θdφ 2+∆θsin2θC dφ 2+ρ2∆θdθ2+r2cos2θdΩ2n,(4.3)r/r h10020001062x1063x1064x106UFig.3.Plots of the eﬀective potential U for D =7,ℓ2a 2/r 4h=0.9∼26,a 2/ℓ2=0.99,m =2×104,x =−0.99.the following energy integral is conserved:H (H T ):= ∞r h dr 1−1dx∆r r 2+a 2|∂x Φ|2+Fr 2+a 2|Φ|2 ,where x =cos(2θ),H T =r −n/2(r 2+a 2)−1/2(1+x )−(n −1)/4Φ(t,r,x )e im ˜ϕ,and F >0.We can show that both U 0and U 1are positive deﬁnite outside the horizon if ℓ2a 2<r 4h .In this case,then,all terms in the energy integral is positive deﬁnite,and no exponentialgrowth of Φis possible.In contrast,for ℓ2a 2>r 4h ,U 1becomes negative in some region.Hence,the eﬀective potential U =∆(U 0+m 2U 1)/F becomes negative in the same region for a suﬃciently large value of m ,as is illustrated in Fig.3.Since m does not appear inside U 0or U 1or in other places in the energy integral,this negative dip of the potential becomes deeper and deeper without bound as m increases.Hence,it is quite likely that this type ofblack hole is unstable for ℓ2a 2>r 4h as in the four-dimensional case.A similar result was obtained for the special Kerr-adS black hole with a 1=···=a N =a in 2N +1dimensional spacetime by Kunduri,Lucietti and Reall.12)§5.DiscussionIn this paper,we have pointed out that for simply rotating Kerr-adS black holes,its stability for tensor-type perturbations is equivalent to that of a massless scalar ﬁeld around these black holes.From this it follows that those black holes are stable for tensor perturba-tions for slow rotation ℓ2a 2≤r 4h .Further,it also strongly suggests that they are unstable dueto superradiance for rapidly rotating case.It will be interesting to check this by numericalcalculations utilising the fact that the scalarﬁeld equation is separable in these background. It will be also interesting to calculate the instability growth time and see whether it blows up in the vanishing cosmological constant limit.AcknowledgementsThe author thanks Akihiro Ishibashi for useful discussions.This work is partly supported by Grants-in-Aid for Scientiﬁc Research from JSPS(No.18540265).References1)Heusler,M.:Black Hole Uniqueness Theorems(Cambridge Univ.Press,1996).2)Kodama,H.:J.Korean Phys.Soc.45,S68–76(2004).3)Volkov,M.S.and Gal’tsov,D.V.:Phys.Reports319,1–83(1999).4)Ishibashi,A.and Kodama,H.:Prog.Theor.Phys.110,901–919(2003).5)Kodama,H.and Ishibashi,A.:Prog.Theor.Phys.110,701–722(2003).6)Kodama,H.and Ishibashi,A.:Prog.Theor.Phys.111,29–73(2003).7)Konoplya,R.and Zhidenko,A.:Nucl.Phys.B777,182–202(2007).8)Gregory,R.and Laﬂamme,R.:Phys.Rev.Lett.70,2837–2840(1993).9)Seahra,S.,Clarkson,C.and Maartens,R.:Phys.Rev.Lett.94,121302(2005).10)Kudoh,H.:Phys.Rev.D73,104034(2006).11)Emparan,R.and Myers,R.C.:JHEP0309,025(2003).12)Kunduri,H.,Lucietti,J.and Reall,H.:Phys.Rev.D74,084021(2006).13)Birmingham,D.and Mokhtari,S.:hep-th/07092388(2007).14)Emparan,R.and Reall,H.:Class.Quantum Grav.23,R169(2006).15)Hawking,S.and Reall,H.:Phys.Rev.D61,024014(1999).16)Cardoso,V.and Dias,O.:Phys.Rev.D70,084011(2004).17)Cardoso,V.,Dias,O.and Yoshida,S.:Phys.Rev.D74,044008(2006).18)Chandrasekhar,S.(Clarendon Press,1983).19)Press,W.and Teukolsky,S.:Nature238,211(1972).20)Zel’dovich,Y.:Sov.Phys.JETP Lett.14,180(1971).21)Cardoso,V.,Dias,O.,Lemos,J.and Yoshida,S.:Phys.Rev.D70,044039(2004).22)Damour,T.,Deruelle,N.and Ruﬃni,R.:Nuovo Cimento Lett.15,257(1976).23)Zouros,T.and Eardley,D.:Ann.Phys.118,139(1979).24)Detweiler,S.:Phys.Rev.D22,2323(1980).25)Furuhashi,H.and Nambu,Y.:Prog.Theor.Phys.112,983–95(2004).26)Dolan,S.:gr-qc/07052880(2007).27)Marolf,D.and Palmer,B.:Phys.Rev.D70,084045(2004).28)Cardoso,V.and Yoshida,S.:JHEP0507,009(2005).29)Dias,O.:Phys.Rev.D73,124035(2006).30)Hawking,S.and Ellis,G.:The Large Scale Structure of Space-time(Cambridge Univ.Press,1973).31)Chru´s ciel,P.T.and Wald,R.M.:Class.Quantum Grav.11,L147–152(1994).32)Galloway,G.J.:Class.Quantum Grav.12,L99–L101(1995).33)Holland,S.,Ishibashi,A.and Wald,R.:Comm.Math.Phys.271,699–722(2007).34)Gibbons,G.W.,L¨u,H.,Page,D.N.and Pope,C.N.:J.Geom.Phys.53,49–73(2005).35)Giammatteo,M.and Moss,I.:Class.Quantum Grav.22,1803–24(2005).36)Kodama,H.,Ishibashi,A.and Seto,O.:Phys.Rev.D62,064022(2000).。

SCI文献翻译DOC

The locust genome provides insight into swarmformation and long-distance flight蝗虫的基因组对集群和长途飞行提供了见解Locusts are one of the world’s most destructive agricultur al pests and represent a useful model system in entomology. Here we present a draft 6.5 Gb genome sequence of Locusta migratoria, which is the largest animal genome sequenced so far. Our findings indicate that the large genome size of L. migratoriais likely to be because of transposable element proliferation combined with slow rates of loss for these elements. Methylome and transcriptome analyses reveal complex regulatory mechanisms involved in microtubule dynamic-mediated synapse plasticity during phase change. We find significant expansion of gene families associated with energy consumption and detoxification, consistent with long-distance flight capacity and phytophagy. We report hundreds of potential insecticide target genes, including cys-loop ligand-gated ion channels, G-protein-coupled receptors and lethal genes. The L. migratoria genome sequence offers new insights into the biology and sustainable management of this pest species, and will promote its wide use as a model system.蝗虫是一个世界上最具破坏性的农业害虫,并且在昆虫学中代表一个有用的模式系统。

科学引文索引

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sci刊物名称及卷首语

sci刊物名称及卷首语SCI是指科学引文索引（Science Citation Index），它是一种学术文献检索工具，由美国科学信息研究所（Institute for Scientific Information，ISI）创建。

SCI收录了全球各领域的科学期刊，并对每篇文章进行索引和引用分析。

SCI刊物的名称有很多，以下是一些常见的SCI刊物及其卷首语的例子：1. Nature（自然）卷首语：“进入到本期的Nature刊物将是一系列富有创造力和刺激性的研究和新闻报道，涵盖了自然科学领域的各个方面。

”2. Science（科学）卷首语：“Science（科学）是一本多学科的科学期刊，旨在发布最新的研究成果和科学评论，以推动科学的进展。

”3. Cell（细胞）卷首语：“Cell（细胞）是一本综合性的生物学期刊，致力于发布高质量和创新性的细胞生物学研究成果。

”4. Physical Review Letters（物理评论快报）卷首语：“Physical Review Lett ers（物理评论快报）是一本涵盖广泛的物理学期刊，发布关于所有物理学领域的重要研究的快报。

”5. Proceedings of the National Academy of Sciences（美国国家科学院院刊）卷首语：“Proceedings of the National Academy of Sciences（美国国家科学院院刊）是一本多学科的科学期刊，刊发关于自然科学、社会科学和工程领域的研究成果。

”需要注意的是，SCI刊物的卷首语可能会根据各刊物的发展和编辑团队的变动而有所变化。

以上仅为一些常见SCI刊物的卷首语的例子，具体的卷首语请以刊物的官方杂志上发布的为准。

(完整版)《科技英语阅读教程》陈勇版课文翻译

核电与核辐射1986年4月26日，切尔诺贝利核电站的一个反应堆发生爆炸，将相当于400颗广岛原子弹的放射性尘降物散布到整个北半球。

在此之前，科学家对辐射对植物和野生动物的影响几乎一无所知。

这场灾难创造了一个活生生的实验室，尤其是在这个被称为禁区的1100平方英里的区域。

1994年，德州理工大学生物学教授罗纳德·切瑟和罗伯特·贝克是首批获准完全进入该区域的美国科学家之一。

“我们抓了一群田鼠，它们看起来和野草一样健康。

我们对此非常着迷。

”贝克回忆说。

当Baker和Chesser对田鼠的DNA进行测序时，他们没有发现异常的突变率。

他们还注意到狼、猞猁和其他曾经稀有的物种在这片区域游荡，仿佛这里是原子野生动物保护区。

2003年由一组联合国机构建立的切尔诺贝利论坛发表了声明一份关于灾难20周年的报告证实了这一观点，称“环境条件对该地区的生物群落产生了积极影响”，将其转变为“一个独特的生物多样性保护区”。

五年前，贝克和切塞尔在这片区域搜寻田鼠。

Mousseau到切尔诺贝利去数鸟，发现了与之相矛盾的证据。

穆萨乌是南卡罗莱纳大学的生物学教授，他的合作者安德斯·佩普·穆勒现在是巴黎南方大学生态、系统学和进化实验室的研究主任。

他们发现该地区家燕的数量要少得多，而那些存活下来的家燕则遭受着寿命缩短、(雄性)生育能力下降、大脑变小、肿瘤、部分白化病(一种基因突变)以及白内障发病率更高的痛苦。

在过去13年发表的60多篇论文中，Mousseau和Moller指出，暴露在低水平辐射下对该区域的整个生物圈产生了负面影响，从微生物到哺乳动物，从昆虫到鸟类。

包括贝克在内的批评人士对穆萨和穆勒持批评态度。

贝克在2006年与切塞尔合著的《美国科学家》(American Scientist)文章中指出，该区域“实际上已成为一个保护区”，穆萨和穆勒的“令人难以置信的结论只得到了间接证据的支持”。

我们所知道的关于电离辐射对健康影响的几乎所有信息都来自于一项正在进行的对原子弹幸存者的研究，该研究被称为寿命研究，简称LSS。