Equivariant Elliptic Genera

数学专业词汇对照以字母 E 开头eccentric angle 离心角eccentric angle of an ellipse 椭圆的离心角eccentric anomaly 离心角eccentricity 离心率eccentricity of a hyperbola 双曲线的离心率echelon matrix 梯阵econometrics 计量经济学eddy 涡流旋涡edge 边edge connectivity 边连通度edge homomorphism 边缘同态edge of a solid 立体棱edge of regression 回归边缘edge of the wedge theorem 楔的边定理editcyclic markov chain 循环马尔可夫链effective area 有效面积effective convergence 有效收敛effective cross section 有效截面effective differential cross section 有效微分截面effective divisor 非负除数effective interest rate 有效利率effective number of replications 有效重复数effective variance of error 有效误差方差effectively computable function 能行可计算函数efficiency 效率efficiency factor 效率因子efficient estimator 有效估计量efficient point 有效点egyptian numerals 埃及数字eigenelement 特摘素eigenfunction 特寨数eigenspace 本照间eigenvalue 矩阵的特盏eigenvalue problem 特盏问题eigenvector 特镇量eigenvector of linear operator 线性算子的特镇量einstein equation 爱因斯坦方程einstein metric 爱因斯坦度量elastic coefficient 弹性常数elastic constant 弹性常数elastic deformation 弹性变形elastic limit 弹性限度elastic modulus 弹性模数elastic scattering 弹性散射elasticity 弹性elastodynamics 弹性动力学electrodynamics 电动力学electromagnetism 电磁electronic computer 电子计算机electronic data processing machine 电子数据处理机electronics 电子学electrostatics 静电学element 元件element of area 面积元素element of best approximation 最佳逼近元素element of finite order 有限阶元素element of surface 面元素elementary 基本的elementary chain 初等链elementary circuit 基本回路elementary conjunction 基本合取式elementary divisor 初等因子elementary divisor theorem 初等因子定理elementary event 简单事件elementary formula 原始公式elementary function 初等函数elementary geometry 初等几何elementary matrix 初等阵elementary number theory 初等数论elementary operation 初等运算elementary path 有向通路elementary set 初等集elementary subdivision 初等重分elementary symmetric function 初等对称函数elementary theory of numbers 初等数沦elevation 正视图eliminant 结式eliminate 消去elimination 消去elimination by substitution 代入消元法elimination method 消元法elimination of unknowns 未知数消去elimination theorem 消去定理ellipse 椭圆ellipse of deformation 变形椭圆ellipsograph 椭圆规ellipsoid 椭面ellipsoid of inertia 惯性椭球ellipsoid of revolution 回转椭面ellipsoid of rotation 回转椭面ellipsoidal 椭面的ellipsoidal coordinates 椭球面]坐标ellipsoidal harmonics 椭球低函数elliptic catenary 椭圆悬链线elliptic coordinates 椭圆坐标elliptic curve 椭圆曲线elliptic cylinder 椭圆柱elliptic cylinder function 椭圆柱函数elliptic differential operator 椭圆型微分算子elliptic equation 椭圆型微分方程elliptic function 椭圆函数elliptic function of the second kind 第二类椭圆函数elliptic function of the third kind 第三类椭圆函数elliptic geometry 椭圆几何elliptic integral 椭圆积分elliptic irrational function 椭圆无理函数elliptic modular function 椭圆模函数elliptic modular group 椭圆模群elliptic motion 椭圆运动elliptic orbit 椭圆轨道elliptic paraboloid 椭圆抛物面elliptic point 椭圆点elliptic quartic curve 椭圆四次曲线elliptic space 椭圆空间elliptic surface 椭圆曲面elliptic system 椭圆型方程组elliptic type 椭圆型ellipticity 椭圆率elongation 伸长embedding 嵌入embedding operator 嵌入算子embedding theorem 嵌入定理empirical curve 经验曲线empirical distribution curve 经验分布曲线empirical distribution function 经验分布函数empirical formula 经验公式empty mapping 空映射empty relation 零关系empty set 空集end 端end around carry 循环进位end device 输出设备endless 无穷的endomorphism 自同态endomorphism group 自同态群endomorphism ring 自同态环endpoint 端点energetic inequality 能量不等式energy 能量energy barrier 能量障碍energy distribution 能量分布energy integral 能量积分energy level 能级energy method 能量法energy momentum tensor 能量动量张量energy norm 能量范数energy operator 能量算子energy principle 能量原理energy space 能量空间energy surface 能面enlarge 扩大enneagon 九边形enriques surface 讹凯斯面ensemble 总体entire 整个的entire function 整函数entire modular form 整模形式entire rational function 整有理函数entire series 整级数entire transcendental function 整超越函数entrance angle 入射角entropy 熵enumerability 可数性enumerable 可数的enumerable set 可数集enumerate 列举enumeration 列举enumeration data 计数数据enumeration problem 列举问题enumerative geometry 枚举几何envelope 包络线envelope of holomorphy 正则包enveloping algebra 包络代数enveloping ring 包络环enveloping surface 包络面epicycle 周转圆epicycloid 外摆线epicycloidal 圆外旋轮线的epimorphic 满射的epimorphic image 满射像epimorphism 满射epitrochoid 长短辐圆外旋轮线epitrochoidal curve 圆外旋轮曲线epsilon chain 链epsilon function 函数epsilon map 映射epsilon neighborhood 邻域epsilon net 网epsilonnumber 数equal 相等的equal set 相等集equal sign 等号equality 等式equality constraint 等式约束equalization 平衡化;同等化equally possible event 相等可能事件equate 使...相等equation 方程equation of a circle 圆方程equation of a curve 曲线方程equation of continuity 连续方程equation of heat conduction 热传导方程equation of higher order 高阶方程式equation of jacobi 雅可比方程equation of mixed type 混合型方程equation of motion 运动方程equation of state 状态方程equation of the straight line 直线方程equation root 方程的根equation with integral coefficients 整系数方程equatorial coordinates 赤道座标equatorial radius 赤道半径equi asymptotic stability 等度渐近稳定性equi luminosity curve 均匀光度曲线equiangular 等角的equiangular spiral 对数螺线equiareal 保积的equiconjugate diameter 等共轭直径equicontinuity 同等连续性equicontinuous 等度连续的equicontinuous functions 等度连续函数equicontinuous set 等度连续集equiconvergence 同等收敛性equidimensional ideal 纯理想equidistant 等距的equidistant curve 等距曲线equilateral 等边的equilateral cone 等边锥面equilateral hyperbola 等轴双曲线equilateral triangle 等边三角形equilibrium 平衡equilibrium concentration 平衡浓度equilibrium conditions 平衡条件equilibrium constant 平衡常数equilibrium diagram 平衡图equilibrium point 平衡点equilibrium principle 平衡原理equilibrium state 平衡状态equipartition 匀分equipotent 等势的;对等的equipotent set 等势集equipotential 等势的equipotential line 等位线equipotential surface 等位面equivalence 等价equivalence class 等价类equivalence problem 等价问题equivalence relation 等价关系equivalent 等价的equivalent equation 等价方程equivalent fiber bundle in g g 等价纤维丛equivalent form 等价形式equivalent functions 等价函数equivalent knot 等价纽结equivalent mapping 保面积映射equivalent matrix 等价阵equivalent metric 等价度量equivalent neighborhood system 等价邻域系equivalent norm 等价范数equivalent point 等价点equivalent proposition 等值命题equivalent states 等价状态equivalent stochastic process 等价随机过程equivalent terms 等价项equivalent transformation 初等运算equivariant map 等变化映射erasing 擦除ergodic chain 遍历马尔可夫链ergodic hypothesis 遍历假说ergodic markov chain 遍历马尔可夫链ergodic property 遍历性ergodic state 遍历态ergodic theorem 遍历定理ergodic theorem in the mean 平均遍历定理ergodic theory 遍历理论ergodic transformation 遍历变换ergodicity 遍历性error 误差error analysis 误差分析error band 误差范围error coefficient 误差系数error component 误差分量error curve 误差曲线error equation 误差方程error estimation 误差估计error function 误差函数error in the input data 输入数据误差error law 误差律error limit 误差界限error mean square 误差方差error model 误差模型error of estimation 估计误差error of first kind 第一类误差error of measurement 测量误差error of observation 观测误差error of reading 读数误差error of second kind 第二类误差error of the third kind 第三类误差error of truncation 舍位误差error originated from input 输入误差error probability 误差概率error sum of squares 误差平方和error variance 误差方差escribe 旁切escribed 旁切的escribed circle 旁切圆essential 本性的essential boundary condition 本质边界条件essential convergence 本质收敛essential epimorphism 本质满射essential extension 本质开拓essential homomorphism 本质同态essential inferior limit 本质下极限essential infimum 本性下确界essential parameter 本质参数essential point 本质点essential singular kernel 本性奇核essential singularity 本性奇点essential spectrum 本质谱essential strategy 本质策略essential superior limit 本质上极限essential supremum 本性上确界essential undecidability 本质不可判定性essentially bounded 本质有界的essentially convergent sequence 本质收敛序列essentially self adjoint operator 本质自伴算子estimable function 可估计函数estimable hypothesis 可估计假设estimate 估计estimation 估计estimation of error 误差估计estimation of parameter 参数的估计estimation region 估计区域estimation theory 估计论estimator 估计量etale neighborhood 层邻域etale space 层空间etale topology 层拓扑etalon 标准euclid factorization theorem for rational integers 因子分解定理euclid lemma 欧几里得引理euclid parallel postulate 欧几里得平行公设euclidean algorithm 欧几里得算法euclidean domain 欧几里得整环euclidean geometry 欧几里得几何euclidean metric 欧几里得度量euclidean norm 欧几里得范数euclidean plane 欧几里得平面euclidean ring 欧几里得整环euclidean space 欧几里得空间euclidean vector space 欧几里得向量空间euler characteristic 欧拉示性数euler class 欧拉类euler constant 欧拉常数euler criterion 欧拉判别准则euler differential equation 欧拉微分方程euler formula 欧拉公式euler identity 欧拉恒等式euler number 欧拉数euler poincare formula 欧拉庞加莱公式euler poincare relation 欧拉庞加莱公式euler polyhedron theorem 欧拉多面体定理euler polynomial 欧拉多项式euler summation formula 欧拉总和公式eulerian angle 欧拉角evaluate 求...的值evaluation 计算evaluation of functions 函数值计算evaluation of integrals 积分计算even 偶数的even function 偶函数even number 偶数even parity 偶数同位even permutation 偶置换evenness 偶数性event 事件everywhere convergent sequence 处处收敛序列evidence 迷evident 迷的evolute 缩闭线evolute surface 渐屈面evolution 开方evolution equation 发展方程evolvent 渐伸线exact cohomology sequence 正合上同凋列exact differential equation 全微分方程exact division 正合除法exact homotopy sequence 正合同伦序列exact solution 精确解exact square 正合平方exactitude 精确度exactness axiom 正合性公理example 例exceed 超过excenter 外心exceptional curve 例外曲线exceptional jordan algebra 例外约当代数exceptional point 例外点exceptional value 例外值excess 超过excess function 超过函数excess of nine 舍九法exchange 交换exchange integral 交换积分exchange lattice 交换格exchange theorem 交换定理excircle 旁切圆excision 切除excision isomorphism 切除同构exclude 排除exclusion 排除exclusive disjunction 不可兼析取exclusive events 互斥事件exclusive or 不可兼的或executive program 执行程序exist 存在existence 存在existence conditions 存在条件existence of extremum 极值的存在existence theorem 存在定理existence theorem for roots 根的存在性定理existence theorem of implicit function 隐函数的存在性定理existential quantifier 存在量词exogenous variable 局外变量exotic space 异种空间expactation vector 期望值向量expand 展开expansion 展开expansion coefficient 展开系数expansion in series 级数展开expansion in terms of eigenfunction 本寨数展开expansion of a determinant 行列式的展开expansion theorem 展开定理expectation 期望值expected gain 期望增益expected payoff 期望增益expected value 期望值expected value vector 期望值向量experiment 实验experimental 实验的experimental error 实验误差explicit difference scheme 显式差分格式explicit differential equation 显式微分方程explicit function 显函数exponent 指数exponent notation 指数记法exponent of convergence 收敛指数exponential 指数函数exponential curve 指数曲线exponential distribution 指数分布exponential equation 指数方程exponential family 指数族exponential form of complex number 复数的指数形式exponential fourier transformation 指数型傅里叶变换exponential function 指数函数exponential integral 积分指数exponential law 指数定律exponential map 指数映射exponential p adic valuation 指数p 进赋值exponential process 指数过程exponential series 指数级数exponential sum 指数和exponential type 指数型exponential valuation 指数赋值exponentially asymptotic stability 指数式渐近稳定exportation 输出express 表示expression 式exradius 外圆半径extend 扩大extended commutator 广义换位子extended complex plane 扩张平面extended ideal 广义理想extended mean value theorem 广义均值定理extended plane 扩张平面extended point transformation 开拓的点变换extended predicate calculus 广义谓词演算extended riemann hypothesis 广义黎曼假设extended unitary group 广义酉群extension 扩张extension module 扩张模extension of a field 域的扩张extension of the residue field 剩余域的扩张extension principle of propositional logic 命题逻辑的外延性原理extension theorem 扩张定理extensionality 外延extensive quantity 外延量extent 范围exterior 外exterior algebra 外代数exterior angle 外角exterior approximation 外逼近exterior boundary problem 外边界问题exterior derivative 外导数exterior differential 外微分exterior differential form 外微分形式exterior differentiation 外微分法exterior domain 外域exterior interior angles 同位角exterior multiplication 外乘exterior normal 外法线exterior point 外点exterior power 外幂exterior problem 外边界问题exterior product 外积exterior product of tensors 张量的外积external 外部的external composition 外部合成external composition law 外部合成律external direct sum 外直和external division 外分external law of composition 外部合成律external memory 外存储器external program 外部程序external ratio 外分比external store 外存储器externally stable set 控制集externally tangent 外切的extract 开方extraction of a root 开方extraneous root 额外根extrapolate 外推extrapolation 外插extremal 极值曲线;极值的extremal element 极值元素extremal function 极值函数extremal length 极值长度extremal point 极值点extremal property 极值性质extremal surface 极值曲面extreme 外项extreme form 极型extreme point 极值点extreme term 外项extreme value 极值extreme value distribution 极值分布extreme value problem 极值问题extremity 端extremum 极值extremum conditions 极值条件extremum problem with subsidiary condition 附加条件极值问题extremum with a condition 条件极值extremum with a constraint 条件极值。

之阿布丰王创作1. Typical of the grasslanddwellers of the continent is the American antelope, or pronghorn. 1.美洲羚羊,或称叉角羚,是该年夜陆典范的草原植物.2. Of the millions who saw Haley's comet in 1986, how many peoplewill live long enough to see it return in the twenty-first century. 2. 1986年看见哈雷慧星的千百万人傍边,有几多人能够长寿到足以目睹它在二十一世纪的回归呢？3. Anthropologists have discovered that fear, happiness, sadness,and surprise are universally reflected in facial expressions. 3.人类学家们已经发现,恐惧,快乐,哀思和惊奇城市行之于色,这在全人类是共通的.4. Because of its irritating effect on humans, the use of phenol asa general antiseptic has been largely discontinued. 4.由于苯酚对人体带有安慰性作用,它基本上已不再被看成经常使用的防腐剂了.5. In group to remain in existence, a profit-making organizationmust, in the long run, produce something consumers consider useful ordesirable. 5.任何盈利组织若要生存,最终都必需生产出消费者可用或需要的产物.6. The greater the population there is in alocality, the greaterthe need there is for water, transportation, and disposal of refuse. 6.一个处所的人口越多,其对水,交通和垃圾处置的需求就会越年夜. 7. It is more difficult to write simply, directly, and effectivelythan to employ flowery but vague expressions that only obscure one's meaning. 7.简明,直接,有力的写作难于花哨,含混而意义模糊的表达. 8. With modernoffices becoming more mechanized, designersareattempting to personalize them with warmer, less severe interiors. 8.随着现代办公室的日益自动化,设计师们正试图利用较为温暖而不太严肃的内部装饰来使其具有亲切感.9. The difference between libel and slander is thatlibel is printedwhile slander is spoken. 9.诽谤和流言的区别在于前者是书面的,而后者是口头的. 10. The knee is the joints where the thigh bone meets the large boneof the lower leg. 10.膝盖是年夜腿骨和小腿胫的连接处.11. Acids are chemical compounds that, in water solution, have asharp taste, a corrosive action on metals, and the ability to turn certain bluevegetable dyes red. 11.酸是一种化合物,它在溶于水时具有强烈的气味和对金属的腐蚀性,而且能够使某些蓝色植物染料变红. 12. Billie Holiday's reputation as a great jazz-blues singerrestson her ability to give emotional depth to her songs. 12. Billie Holiday's作为一个爵士布鲁斯乐杰出歌手的名声建立在能够赋予歌曲感情深度的能力. 13. Essentially, a theory is an abstract, symbolic representation ofwhat is conceived to be reality. 13.理论在实质上是对认识了的现实的一种笼统和符号化的表达.14. Long before children are able to speak or understanda language,they communicate through facial expressions and by making noises. 14.儿童在能说或能听懂语言之前,很久就会通过面部脸色和靠发出噪声来与人交流了. 15. Thanks to modern irrigation, crops now grow abundantly in areaswhere once nothing but cacti and sagebrush could live. 15.受今世灌溉(技术设施)之赐,农作物在原来只有仙人掌和荞属科植物才华生存的处所旺盛的生长. 16. The development of mechanical timepieces spurred the search formore accurate sundials with which to regulate them. 16.机械计时器的发展促使人们寻求更精确的日晷,以便校准机械计时器. 17. Anthropology is a science in that anthropologists use a rigorousset of methods and techniques to document observations that can be checked byothers. 17.人类学是一门科学,因为人类学家采纳一整套强有力的方法和技术来记录观测结果,而这样记录下来的观测结果是供他人核查的. 18. Fungi are important in the process of decay, which returnsingredients to the soil, enhances soil fertility, and decomposes animal debris. 18.真菌在腐化过程中十分重要,而腐化过程将化学物质回馈于土壤,提高其肥力,并分解植物粪便. 19. When it is struck, a tuning fork produces an almost pure tone,retaining its pitch over a long period of time. 19.音叉被敲击时,发生几乎纯质的音调,其音量经久不衰. 20. Although pecans are most plentiful in the southeastern part ofthe United States, they arefound as far north as Ohio and Illinois.20.虽然美洲山河桃树最集中于美国的西北部可是在北至俄亥俄州及伊利诺州也能看见它们.21.Eliminating problems by transferring the blame to others is often calledscape-goating. 21.用怪罪他人的法子来解决问题通常被称为寻找替罪羊. 22. The chief foods eaten in any country dependlargely on what grows best in its climate and soil. 22.一个国家的主要食物是什么,年夜体取决于什么作物在其天气和土壤条件下生长得最好.23. Over a very large number of trials, theprobability of an event's occurring is equal to the probability that it willnot occur. 23.在年夜量的实验中,某一事件发生的几率即是它不发生的几率. 24. Most substance contractwhen they freeze so thatthe density of a substance'ssolid is higher than the density of its liquid. 24.年夜大都物质遇冷收缩,所以他们的密度在固态时高于液态. 25. The mechanism by which brain cells store memoriesis not clearly understood. 25.年夜脑细胞贮存记忆的机理其实不为人明白. 26. By the middle of the twentieth century, paintersand sculptors in the United States had begun to exert a great worldwideinfluence over art. 26.到了二十一世纪中叶,美国画家和雕塑家开始在世界范围内对艺术发生重年夜影响. 27. In the eastern part of New Jersey lies the city of Elizabeth,a major shipping and manufacturing center. 27.伊丽莎白市,一个重要的航运和制造业中心,坐落于新泽西州的东部. 28. Elizabeth Blackwell, the first woman medicaldoctor in the United States,founded the New York Infirmary, an institution that has always had a completelyfemale medical staff. 28. Elizabeth Blackwell,美国第一个女医生,创立了员工一直为女性纽约诊所.29. Alexander Graham Bell once told his family thathe would rather be remembered as a teacher of the deaf than as the inventor ofthe telephone. 29. Alexander Graham Bell曾告诉家人,他更愿意让后人记住他是聋子的老师,而非德律风的发明者. 30. Because its leaves remain green longafter beingpicked, rosemary became associated with the idea of remembrance. 30.采摘下的迷迭香树叶常绿不衰,因这人们把迷迭香树与怀念联系在一起.31. Although apparently rigid, bones exhibit a degree of elasticitythat enables the skeleton to withstand considerable impact. 31.骨头看起来是脆硬的,但它也有一定的弹性,使得骨骼能够接受相当的冲击. 32. That xenon could not FORM chemical compounds wasonce believed by scientists. 32.科学家曾相信：氙气是不能形成化合物的. 33. Research into the dynamics of storms is directedtoward improving the ability to predict these events and thus to minimizedamage and avoid loss oflife. 33.对风暴乱力学的研究是为了提高风暴预测从而减少损失,防止人员伤亡. 34. The elimination of inflation would ensure thatthe amount of money used in repaying a loan would have the same value as theamount of money borrowed. 34.消除通货膨胀应确保还贷的钱应与所存款的价值相同. 35. Futurism, an early twentieth-century movement inart, rejected all traditions and attempted to glorify contemporary life byemphasizing the machine and motion. 35.未来主义,二十世纪早期的一个艺术思潮.拒绝一切传统,试图通过强调机械和静态来美化生活. 36. One ofthe wildest and most inaccessible parts ofthe United States is the Everglades where wildlife is abundant and largelyprotected. 36. Everglades是美国境内最为荒凉和人迹罕至的地域之一,此处有年夜量的野生动植物而且年夜多受(法律)呵护. 37. Lucretia Mott's influence was so significant thatshe has been credited by someauthorities as the originator of feminism in the United States. 37. Lucretia Mott's的影响巨年夜,所以一些权威部份认定她为美国女权运动的开创人. 38. The activities of the international marketingresearcher are frequently much broader than those of the domestic marketer. 38.国际市场研究者的活动范围经常较国内市场研究者广阔. 39. The continental divide refers to an imaginaryline in the North American Rockies that divides the waters flowing into the Atlantic Ocean from those flowing into the Pacific. 39.年夜陆分水岭是指北美洛矶山脉上的一道想象线,该线把年夜西洋流域和太平洋流域区分开来. 40. Studies of the gravity field of the Earthindicate that its crust and mantle yield when unusual weight is placed on them.40.对地球引力的研究标明,在不寻常的负荷之下地壳和地幔会发生位移.41.The annual worth of Utah'smanufacturing is greater than that of its mining and farming combined. 41.尤它州制造业的年产值年夜于其工业和农业的总和. 42. The wallflower is so called because its weakstems often grow on walls and along stony cliffs for support. 42.墙花之所以叫墙花,是因为其懦弱的枝干经常要靠墙壁或顺石崖生长,以便有所依附. 43. It is the interaction between people, rather thanthe events that occur in their lives, that is the main focus of socialpsychology. 43.社会心理学的主要焦点是人与人之间的交往,而不是他们各自生活中的事件. 44. No social crusade aroused ElizabethWilliams'enthusiasm more than the expansion of educational facilities for immigrants tothe United States. 44.给美国的新移民增加教育设施比任何社会运动都更多的激发了Elizabeth Williams的热情. 45. Quails typically have short rounded wings thatenable them to spring into full flight instantly when disturbed intheir hidingplaces. 45.典范的鹌鹑都长有短而圆的同党,凭此他们可以在受惊时一跃而起,飞离它们的潜藏地. 46. According to anthropologists, the earliestancestors of humans that stood upright resembled chimpanzeesfacially, withsloping foreheads and protruding brows.46.根据人类学家的说法,直立行走的人的开山祖师面部轮廓与黑猩猩相似,额头后倾,眉毛突出. 47. Not until 1866 wasthe fully successfultransatlantic cable finally laid.47.直到1866年第一条横跨年夜西洋的电缆才完全胜利的架通.48. In his writing, John Crowe Ransom describes whathe considers the spiritual barrenness of society brought about by science andtechnology. 48. John Crowe Ransom 在他的著作中描述了他认为是由科学技术给社会带来的精神贫困.49. Children with parents whose guidance isfirm,consistent, and rational are inclined to possess high levels ofself-confidence. 49.父母的教导如果坚定,始终如一和理性,孩子就有可能布满自信.50. The ancient Hopewell people of North America probably cultivated corn and other crops,but hunting and gathering were still of critical importance in their economy. 50.北美远古的Hopewell人很可能种植了玉米和其他农作物,但狩猎和收集对他们的经济贸易仍是至关重要的.51. Using many symbols makes it possible to put alarge amount of inFORMation on a single map. 51.使用多种多样的符号可以在一张舆图里放进年夜量的信息. 52. Anarchism is a term describing a cluster ofdoctrines and attitudes whose principal uniting feature is the beliefthatgovernment is both harmful and unnecessary. 52.无go-vern-ment主义这个词描述的是一堆理论和态度,它们的主要共同点在于相信go-vern-ment是有害的,没有需要的. 53. Probably no man had more effect on the dailylives of most people in the Untied States than did Henry Ford a pioneer inautomobile production. 53.恐怕没有谁对年夜大都美国人的日常生活影响能超越汽车生产的先驱亨利.福特. 54. The use of well-chosen nonsense words makespossible the testing of many basic hypotheses in the field of languagelearning. 54.使用精心挑选的无意义辞汇,可以检验语言学科里许多基本的假定. 55. The history of painting is a fascinating chain ofevents that probably began with the very first pictures ever made. 55.优化历史是由一连串的迷人事件组成,其源头年夜概可以上溯到最早的图画. 56. Perfectly matched pearls, strung into anecklace,bring a far higher price than the same pearls told individually. 56.相互般配的珍珠,串成一条项链,就能卖到比独自售出好很多的价钱. 57. During the eighteenth century, Little Turtle waschief of the Miami tribe whose territory becamewhat is now Indiana and Ohio. 57.十八世纪时,"小乌龟"是迈阿密部落的酋长,该部落的地皮就是今天的印第安那州和俄亥俄州. 58. Among almost seven hundredspecies of bamboo,some are fully grown at less than a foot high, while others can grow three feetin twenty-four hours. 58.在竹子的近七百个品种中,有的全长成还不到一英尺,有的却能在二十四小时内长出三英尺. 59. Before staring on a sea voyage, prudentnavigators learn the sea charts, study the sailing directions, and memorizelighthouse 本地s to prepare themselves for any conditionsthey might encounter. 59.谨慎的航海员在返航前,会研究航向,记录的灯塔的位置,以便对各种可能呈现的情况做到有备无患.60. Of all the economically important plants, palms have been theleast studied. 60.在所有的经济作物中,棕榈树获得的研究最少.61.Buyers and sellers should be aware of new developments in technology can anddoes affect marketing activities. 61.购买者和销售者都应该留意技术的新发展,原因很简单,因为技术能够而且已经影响着营销活动. 62. The application of electronic controls madepossible by the microprocessor and computer storage have multiplied the uses ofthe modern 无效writer. 62.电脑贮存和由于电子微处置机得以实现的电控运用成倍的增加了现代打字机的功能.63. The human skeleton consists of more than twohundredbones bound together by tough and relatively inelastic connectivetissues called ligaments. 63.人类骨骼有二百多块骨头组成,住些骨头石油坚韧而相对缺乏弹性的,被称为韧带的结蒂组连在一起. 64. The pigmentation of a pearl is influenced by the 无效of oyster in which it develops and by the depth, temperature, andthe salt content ofthe water in which the oyster lives. 64.珍珠的色泽受到作为其母体牡蛎种类及牡蛎生活水域的深度,温度和含盐度的制约. 65. Although mockingbirds superbly mimic the songsand calls of many birds, they can nonetheless be quickly identified asmockingbirds by certain aural clues. 65.尽管模仿鸟学很多种鸟的鸣叫声惟妙惟肖,但人类还是能够依其声音上的线索很快识别它们. 66. Not only can walking fish live out of water, butthey can also travel short distances over land. 66.鲇鱼不单可以离开水存活,还可以在岸上短距离移动. 67. Scientists do not know why dinosaurs becameextinct, but some theories postulate that changers in geography, climate, andsea levels were responsible. 67.科学家不知道恐龙为何绝种了,可是一些理论推断是地舆,气候和海平面的变动造成的. 68. The science of horticulture, in which the primaryconcerns are maximum yield and superior quality, utilizes inFORMationderivedfrom other sciences. 68.主要目的在于丰富和优质的农艺学利用了其他科学的知识. 69. Snow aids farmers by keeping heart in the lowerground levels, thereby saving the seeds from freezing. 69.雪对农民是一种帮手,因为它坚持地层土壤的温度,使种子不致冻死.70. Even though the precise qualities of hero in literary words mayvary over time, the basic exemplary function of the hero seems to remainconstant. 70.历代文学作品中的英雄赋性虽各有千秋,但其昭世功力却是恒古不变的. 71. People in prehistoric times created paints bygrinding materials such as plants and clay into power and then adding water. 71.史前的人们制造颜料是将植物和泥土等原料磨成粉末,然后加水. 72. Often very annoying weeds, goldenrods crowd outless hardy plants and act as hosts to many insect pests. 72.hj花通常令人生厌,它挤走不那么顽强的植物,并找来很多害虫. 73. Starting around 7000 B.C., and for the next fourthousand years, much of the Northern Hemisphere experienced temperatures warmerthan at present. 73.年夜约从公元前七千年开始,在四千年傍边,北半球的温度比现在高. 74. When Henry Ford first sought financial backingfor making cars, the very notion of farmers and clerks owning automobileswasconsidered ridiculous. 74.当亨利.福特最初制造汽车为寻求资金支持时,农民和一般职员也能拥有汽车的想法被认为是可笑的. 75. Though once quite large, the populationof thebald eagle across North America hasdrastically declined in the past forty years. 75.北美秃头鹰的数量一度很多,但在近四十年中全北美的秃头鹰数量急剧下降. 76. The beaver chews down trees to get food andmaterial with which to build its home. 76.水獭啃倒树木,以便取食物并获得造窝的资料. 77. Poodles were once used as retrievers in duckhunting, but the American Kennel Club does not consider them sporting dogsbecause they are now primarily kept as pets. 77.长卷毛狗曾被用作猎鸭时叼回猎物的猎犬,可是美国KennelClub却不供认它们为猎犬,因为它们现在年夜大都作为宠物饲养. 78. As a result of whatis now know in physics andchemistry, scientists have been able to make important discoveries in biologyand medicine. 78.物理学和化学的一个功效是使得科学家们能在生物学和医学上获得重年夜发现. 79. The practice of making excellent films based onrather obscure novels has been going on so long in the United Statesas toconstitute a tradition. 79.根据默默无闻的小说制作优秀影片在美国由来已久,已经成为传统.80. Since the consumer considers the best fruit to be that which isthe most attractive, the grower must provide products that satisfy thediscerning eye. 80.因为顾客认为最好的水果应该看起来也是最漂亮的,所以种植者必需提供能满足挑剔眼光的产物.81.Television the most pervasive and persuasive of modern technologies, marked byrapid change and growth,is moving into a new era, an era of extraordinarysophistication and versatility, which promises to reshape our lives and ourworld. 81.电视,这项从迅速变动和生长为标识表记标帜的最普及和最有影响力的现代技术,正在步入一个新时代,一个极为成熟和多样化的时代,这将重塑我们的生活和世界. 82. Television is more than just an electronics; itis a means of expression, as well as a vehicle for communication, and as suchbecomes a powerful tool for reaching other human beings. 82.电视不单仅是一件电器；它是表达的手段和交流的载体并因此成为联系他人的有力工具. 83. Even more shocking is thefact that the numberand rate of imprisonment have more than doubled over the past twenty years, andrecidivism------that is the rate for re-arrest------is more than 60 percent. 83.更让人受惊的事实是监禁的数目和比例在过去的二十年中翻了一番还有余,以及累犯率--即再次拘押的比例--为百分之六十强. 84. His teaching began at the Massachusetts Instituteof Technology, but William Rainey Harper lured him to the new university of Chicago,where he remained officially for exactly a generation and where his students inadvanced composition found him terrifyingly frigid in the classroom butsympathetic and understanding in their personal conferences. 84.他的教书生涯始于麻省理工学院,可是WilliamRainey Harper把他吸引到了新成立的芝加哥年夜学.他在那里正式任职长达整整一代人的时间.他的高级作文课上的学生觉得他在课上古板得可怕,但私下交流却富有同情和理解. 85. The sloth pays suchlittle attention to itspersonal hygiene that green algae grow on its coarse hair and communities of aparasitic moth live in the depths of its coat producingcaterpillars whichgraze on its mouldy hair. Its muscles are such that it is quits incapable ofmoving at a speed of over a kilometer an hour even over the shortest distancesand the swiftest movement it can make is a sweep of its hooked arm. 85.树獭即不讲究卫生,以至于它粗拙的毛发上生出绿苔,成群的寄生蛾生长在它的皮毛深处,酿成毛毛虫,并以它的脏毛为食.她的肌肉不能让他哪怕在很短的距离以内以每小时一公里的速度移动.它能做的最敏捷的举措就是挥一挥它弯曲的胳膊. 86. Artificial flowers are used for scientific aswell as for decorative purposes. They are made from a variety of materials,such as way and glass, so skillfully that they can scarcely be distinguishedfrom natural flowers. 86.人造花卉即可用于科学目的,也可用于装饰目的,它们可以用各种各样的资料制成,臂如蜡和玻璃；其制作如此精巧,几乎可以以假乱真. 87. Three years of research at an abandoned coal minein Argonne, Illinois,have resulted in findings that scientists believe can help reclaim thousands ofmine disposal sites that scar the coal-rich regions of the United States. 87.在伊利诺州Angonne市的一个废弃煤矿的三年研究取得了功效,科学家们相信这些功效可以帮手改造把美国产煤区弄得伤痕累累的数千个旧煤场. 88. When the persuading and the planning for thewestern railroads had finally been completed, the really challenging taskremained: the dangerous, sweaty, backbreaking, brawling business of actuallybuilding the lines. 88.当有关西部铁路的说服和规划工作终于完成后,真正艰难的任务还没有开始；即危险,费劲,需要伤筋动骨和吵喧嚷嚷的建造这些铁路的实际工作. 89. Because of the space crunch, theArt Museum hasbecome increasingly cautious inconsidering acquisitions and donations of art,in some cases passing up opportunities to strengthen is collections. 89.由于空间缺乏,艺术博物馆在考虑购买和接受捐赠的艺术品是越来越慎重,有些情况下放弃其进一步改善收藏的机会.90. The United States Constitution requires that President be anatural-born citizen, thirty-five years of age or older, who has lived in the United Statesfor a minimum of fourteen years. 90.美国宪法要求总统是生于美国外乡的公民,三十五岁以上,而且在美国居住了至少十四年. 91. Arid regions in the southwestern United Stateshave become increasingly inviting playgrounds for the growing number ofrecreation seekers who own vehicles such as motorcycles or powered trail bikesand indulge in hill-climbing contests or in caving new trails in the desert.91.美国西部的穷山恶水正成为玩耍的处所,对越来越多拥有摩托车或越野单车类车辆的,喜欢放纵于爬坡角逐或开辟新的沙漠通道的寻欢作乐者具有不竭增长的吸引力. 92. Stone does decay, and so tools of long ago haveremained when even thebones of the man who made them have disappeared withouttrace. 92.石头不会腐烂,所以以前的(石器)工具能保管下来,虽然它们的制造者已经消失的无影无踪. 93. Insects would make it impossible for us to livein the world;they would devour all our crops and kill our flocks and herds, ifit were not for the protection we get from insect-eating animals. 93.昆虫就将会使我们无法在这个世界上居住；如果我们没有受到以昆虫为食的植物的呵护,昆虫就会吞嚼失落我们所有的庄稼并杀死我们饲养的禽兽. 94. It is true that during their explorations theyoften faced difficulties and dangers of the most perilous nature, equipped in amanner which would make a modern climber shudder at the thought, but they didnot go out of their way to court such excitement. 94.确实,他们在探险中遇到了极具威胁性的困难和危险,而他们的装备会让一个现代爬山者想一想城市浑身战栗.不外他们其实不是刻意去追求安慰的.95. There is only one difference between an old manand a young one: the young man has a glorious future beforehim and old one hasa splendid future behind him: and maybe that is where the rub is. 95.老人和年轻人之间只有一个区别：年轻人的前面有辉煌的未来,老年人残酷的未来却已在它们身后.这也许就是困难之所在. 96. I find young people exciting. They have an air offreedom, and they have not a dreary commitment to mean ambitions orlovecomfort. They are not anxious social climbers, and they have no devotion tomaterial things. 96.我们位年强人振奋.它们带有自由的气息,他们不会为狭隘的野心和贪婪享受而孜孜以求.他们不是焦虑的向上爬的人,他们不会对物质性的工具难舍难分. 97. I am always amazed when I hear people saying thatsport creates goodwill between the nations, and that if only the common peoplesof the world could meet one another at football or cricket, they would have noinclination to meet on the battlefield. 97.每次我听说体育运动能够在国家间建立起友好感情,说世界各地的普通人只要能在足球场或板球场上相遇就会没有兴趣在战场上相遇的话,我都倍感惊讶. 98. It is impossible to say simply for the fun andexercise: as soon as the question of prestige arises, as soon as you feel thatyou and some larger unit will be disgraced if you lose, the most savagecombative instincts are around. 98.没有可能仅仅为了娱乐或熬炼而运动：一旦有了问题,一旦你觉得你输了你和你所属团体会有失体面时,你最野蛮的好斗天性就会被激发出来. 99. It has been found that certain bats emit squeaksand by receiving the echoes, they can locate and steer clear ofobstacles------or locate flying insects on which they feed. This echo-本地in bats is often compared with时间：二O二一年七月二十九日radar, the principle of which issimilar. 99.人们已经发现,某些蝙蝠发出尖叫声并靠接受回响来锁定和防止障碍物--或者找到它们赖以为生的昆虫.蝙蝠这种回响定位法常拿来和原理与之很相近似的雷达相比. 100. As the time and cost of making a clip drop to afew days and a few hundred dollars, engineers may soon be free to let theirimaginations soar without being penalized by expensive failure. 100.随着芯片制造时间和费用降低到了几天和几百美元,工程师们可能很快可以任他们的想象驰骋而不会被昂贵的失败所处分.时间：二O二一年七月二十九日。

a r X i v :081.4733v1[mat h.A G]3J a n28Yang-Mills theory and Tamagawa Numbers:the fascination of unexpected links in mathematics Aravind Asok,Brent Doran and Frances Kirwan February 3,20081Introduction and overview This article is an expanded version of the third author’s presidential address to the London Mathematical Society in November 2005,which was based on work with the other two authors over the preceding year.The title was inspired by Michael Atiyah’s presidential address delivered in 1976[Ati78]in which he said “The aspect of mathematics which fascinates me most is the rich interaction between its different branches,the unexpected links,the surprises.”The unexpected link which is the topic of this article was remarked on by Atiyah himself and his collaborator Raoul Bott in their fundamental 1983pa-per [AB83]on the Yang-Mills equations over Riemann surfaces.In this paper Atiyah and Bott used ideas coming from Yang-Mills theory and equivariant Morse theory to derive inductive formulae for the Betti numbers of the moduli spaces M (n,d )of stable vector bundles of rank n and degree d over a fixed compact Riemann surface C of genus g ≥2,when n and d are coprime.(We will assume throughout this introduction that n and d are coprime integers with n >0.)Equivalent formulae had been obtained earlier by Harder and Narasimhan [HN75]and Desale and Ramanan [DR75]using arithmetic tech-niques and the Weil conjectures.In the latter approach a crucial ingredient was the fact,proved by Weil,that the volume of a certain locally symmetric space attached to SL n with respect to a canonical measure –an invariant known asthe Tamagawa number of SL n –is 1.Atiyah and Bott observed that although the two methods came from very different branches of mathematics,namely arithmetic and physics,there was a formal correspondence between them,with the Tamagawa number of SL n (or equivalently the function field analogue of the Siegel formula)playing,roughly speaking,the rˆo le of the cohomology of the classifying space of the gauge group in the Atiyah-Bott approach.They asked for a deeper understanding of this observation and in particular for a geometric explanation,exploiting the analogy with equivariant cohomology,of the fact that the Tamagawa number of SL n is1.Contributions since then towards such understanding have included work by Bifet,Ghione and Letizia [Bif89,BGL94],providing another inductive procedure1for calculating the Betti numbers of the moduli spaces which is in some sense intermediate between the arithmetic approach and the Yang-Mills approach,and more recently,work by Teleman,Behrend,Dhillon and others on the moduli stack of bundles over C[BDa,BDb,Dhi06,Tel98].The formal correspondence observed by Atiyah and Bott between the induc-tive formulae obtained from the Yang-Mills and arithmetic points of view arises because both depend on stratifications of spaces whose points represent vec-tor bundles over C,with the stratification induced by the“Harder-Narasimhan types”of the bundles.In each case it is the open stratum,corresponding to semistable bundles,which needs to be understood,and the inductive calcula-tion comes from combining a simple description of the other strata(in terms of semistable strata for the corresponding problem with strictly smaller values of n and varying values of d)together with knowledge of the whole space.In the arithmetic approach the space to be stratified is a coset space of the group SL n(A K)associated with the ad`e le ring A K of the functionfield K of a nonsin-gular projective curve over afinitefield.The Tamagawa measure of the whole space is the(countably infinite)sum of the measures of the strata.In the Yang-Mills approach Atiyah and Bott stratify the infinite-dimensional affine space A of unitary connections on afixed C∞bundle of rank n and degree d over C, and they show that the stratification is“equivariantly perfect”with respect to the gauge group,so that the equivariant cohomology algebra of A is isomorphic as a vector space to the sum over the strata of their equivariant cohomology algebras,shifted in degree by their real codimensions.The cohomology of the moduli spaces M(n,d)of bundles over a compact Riemann surface has,of course,more structure than is revealed by its Betti numbers.It has been an object of study for several decades,first when n=2 and then for general n,from many points of view including mathematical physics[AB83,Wit92],matrix divisors[BGL94,Bif89],extended moduli spaces [JW94,HJ94,Jef94],group valued moment maps and quasi-Hamiltonian re-ductions[AMM98,AMW00,AMW01,AMW02,MW99,Mei05]and others [Dhi06,Kir86a,Kir86b,JK98,JKKW06],though the ideas of Atiyah and Bott have been fundamental for much of this progress.Following a long line of work initiated by Grothendieck in the1960s,Bloch and Voevodsky have developed sophisticated versions of cohomology(motivic cohomology,see[Blo86,Voe00,MVW06])for algebraic varieties defined over arbitraryfields.Voevodsky and Morel had a broader vision(see[MV99]):they sought to build a homotopy theory for schemes over afield k where the affine line plays a role analogous to that played by the unit interval in ordinary homotopy theory.In the resulting homotopy category,called the A1or motivic homotopy category,there are two different analogues of the circle:the simplicial circle which is obtained from the affine line by glueing together0and1(represented by the affine nodal cubic curve)and the Tate circle A1−{0}.Corresponding to these two analogues of the circle,a pair of integers index the motivic cohomology groups of a smooth scheme X over afield k,reflecting the fact that these groups form a bigraded ring.Motivic cohomology groups for smooth schemes over k have many properties analogous to ordinary singular cohomology,including an2appropriate form of homotopy invariance,Mayer-Vietoris and Gysin long exact sequences.However,motivic cohomology encodes far more information;for example,in contrast with ordinary singular cohomology,the motivic cohomology of a point Spec k is quite large,with its degree(p,p)part being isomorphic to the p-th Milnor K-group of thefield k(see[MVW06]Chapter4).Furthermore, if X is a smooth k-scheme,the motivic cohomology groups H2p,p(X,Z)are isomorphic to the Chow groups of codimension p cycles on X modulo rational equivalence.The aim of this article is threefold:to announce results,produced in the setting of A1-homotopy theory,on the motivic cohomology(and hence its many realizations)of quotients in the sense of Mumford’s geometric invariant theory or GIT[ADK],generalizing what was known for singular cohomology of GIT quotients;to explain how methods used over the last three decades to study the singular cohomology of the moduli spaces M(n,d)can thence be adapted to study the motivic cohomology of moduli spaces of bundles on a smooth projec-tive curve C over an algebraically closedfield k;and at the same time to extend our understanding of the link between Yang-Mills theory and Tamagawa num-bers remarked on by Atiyah and Bott,by re-examining some of their essentially homotopy theoretic considerations in a more algebraic modern light.This study is based on an adaptation to the setting of motivic cohomology of the inductive methods obtained in the third author’s thesis[Kir84]for calcu-lating the Betti numbers of a GIT quotient[MFK94]of a nonsingular complex projective variety X by a linear action of a complex reductive group G.These methods were themselves inspired by the work of Atiyah and Bott[AB83]and involve applying equivariant Morse theory to the norm-square of an appropriate moment map,which is the analogue of the Yang-Mills functional in[AB83].The associated stratification of X has an alternative purely algebraic description,in-dependent of Morse theory,which is valid much more generally than just over the complex numbers C:the semistable points of X(in the sense of GIT)form an open stratum,and the other strata can be described inductively in terms of the semistable points of nonsingular projective subvarieties of X under appro-priately linearized actions of reductive subgroups of G.In thefinite-dimensional algebro-geometric setting,most of the results of[Kir84]can be adapted to ap-ply to motivic cohomology[ADK].These results can then be used to study the motivic cohomology of moduli spaces of vector bundles over a curve C.Much beautiful work has been done recently on the moduli of bundles over a curve which can be used to extract similar information[dB01,dB02,BDa, Dhi06].Our aim here is to derive this information as an application of a general theory of cohomology of GIT quotients,and to offer some insights gleaned from returning to a mapping space perspective on the moduli space of bundles. OutlineIn§2of this paper we describe the two equivalent inductive procedures for calculating the Betti numbers of M(n,d)provided by the arithmetic and Yang-Mills approaches.The Yang-Mills approach of Atiyah and Bott[AB83],which3uses equivariant Morse theory,has as its basic ingredient a simple description given in[AB83]of the cohomology of the classifying space of the gauge group, while the arithmetic approach of[HN75,DR75]uses Tamagawa measures and reduces to the functionfield version of the Siegel formula,or equivalently to the fact that the Tamagawa number of SL n is1.These two approaches rely on what can be regarded as infinite-dimensional quotient constructions of the moduli spaces M(n,d).A third approach,closely related to that used by Bifet,Ghione and Letizia in[BGL94],involves the construction of the moduli spaces M(n,d)asfinite-dimensional GIT quotients which can be regarded asfinite-dimensional approximations to the Yang-Mills construction.This involves studying spaces of maps into Grassmannians and matrix divisors,and provides an inductive calculation of the Betti numbers of the moduli spaces in terms of the cohomology of symmetric powers of the curve C(this cohomology is well known[Mac62]).Here the inductive formulae can be obtained from equivariant Morse theory as in the Yang-Mills approach,but in thisfinite-dimensional setting the Weil conjectures provide an alternative derivation by using the algebraic description of the Morse strata and counting points on associated varieties defined overfinitefields.In§3we move into the motivic world;our aim is to show that thefinite di-mensional GIT construction of M(n,d)used in the third approach to calculate Betti numbers can also be used to study the motivic cohomology of M(n,d). Thefirst step is to make sense of equivariant motivic cohomology;this is done using a straightforward modification of the Borel construction in topology using work of Morel and Voevodsky.In§4we describe how to adapt the methods of [Kir84]on the cohomology of GIT quotients to the setting of motivic cohomol-ogy,and in§5we apply these to obtain an inductive description of the motivic cohomology groups of M(n,d)in terms of the motivic cohomology of products of symmetric powers of the curve C.In thefinal section§6we leave motivic cohomology and return to the original question of the relationship between Yang-Mills theory and Tamagawa measures. We observe that the inductive procedure for calculating the Betti numbers of M(n,d)which usesfinite-dimensional approximations to the Yang-Mills pic-ture,via maps into Grassmannians and matrix divisors,is directly equivalent to the Yang-Mills approach through a generalization of Segal’s theorem on the topology of spaces of rational functions[Seg79].This theorem makes precise the sense in which the Yang-Mills approach is an infinite-dimensional limit of the corresponding procedure using maps into Grassmannians.In a similar way the arithmetic methods used by Harder and Narasimhan to provide an inductive calculation of the Betti numbers of M(n,d)can be regarded as an infinite-dimensional limit of the alternativefinite-dimensional approach which involves counting points on associated varieties overfinitefields.The Weil conjectures then provide thefinal link in the chain connecting the Yang-Mills and arithmetic viewpoints.4AcknowledgementsThe authors would like to thank Tamas Hausel,Michael McQuillan,James Par-son,Burt Totaro and Akshay Venkatesh for helpful discussions and comments. 2A review of the classical constructionsThe moduli spaces of stable vector bundles on a smooth projective curve C over afield k have different incarnations depending on thefield k.Over afield k with sufficiently many elements,these moduli spaces can be constructed by means of geometric invariant theory.If k=C and we view the complex points of C as a compact Riemann surface,we have a differential geometric construction using an interpretation of stable vector bundles in terms of connections.If k=F q, there is an interpretation of such vector bundles in terms of ad`e les.We review the last two of these constructions in this section.We will discuss the GIT construction in§5.Historically,the computation of the cohomology of these moduli spaces was first achieved using number theory and then using Yang-Mills theory,while algebraic geometry provides a logical bridge between these two contexts.In this section we will review the differential geometric and the arithmetic approaches to computing the cohomology of the moduli spaces.Throughout this section, C will denote a compact Riemann surface or a smooth projective algebraic curve defined over afield k.We abuse notation in this way to emphasize the interchangeability of the different points of view,the object under consideration being clear from its context.2.1Yang-Mills and Riemann surfacesLet C be a compact Riemann surface of genus g.In order to avoid having to consider special cases,we will assume throughout that g is at least2.By convention,holomorphic vector bundles on C will be denoted by calligraphic letters E,F,...and the underlying C∞-complex vector bundles will be denoted by Roman letters E,F,....Furthermore,all bundles will be assumed to be C∞-bundles;thus the term complex vector bundle should be read as C∞-complex vector bundle.Given a complex vector bundle E,the bundle of frames of E is a GL n(C)-principal bundle.This construction defines a bijection between the set of complex vector bundles of rank n on C and the set of GL n(C)-principal bundles(with inverse given by forming the vector bundle associated with the standard n-dimensional representation of GL n).By abuse of terminology,we will use the same notation E for the GL n(C)-principal bundle associated with a complex vector bundle E.Topologically,complex vector bundles offixed rank n on C are classified by homotopy classes of maps to the space BGL n,which is(homotopy equivalent to) the Grassmannian of n-dimensional quotients of an infinite dimensional complex vector space.The degree orfirst Chern class d∈H2(C,Z),which can be identified with Z by pairing with the fundamental class,is also a topological5invariant and the rational numberµ(E)=d/n is called the slope of E.We will also writeµ(E)for the slope of the complex vector bundle E underlying a holomorphic vector bundle E.If E is a holomorphic vector bundle,we call E stable(respectively semistable) if every proper holomorphic subbundle F of E satisfiesµ(F)<µ(E)(respectively µ(F)≤µ(E)).Note that when n and d are coprime,every semistable bundle of rank n and degree d is stable.Let E be afixed complex vector bundle of rank n and degree d over C.The group Aut C(E)of all complex vector bundle automorphisms of E is called the complexified gauge group of E in the Yang-Mills context(see below)and denoted G C.Let C=C(n,d)denote the space of all holomorphic structures on E,and let C s(respectively C ss)be the subset of C consisting of stable(respectively semistable)holomorphic structures on E.Since C is one complex-dimensional, all almost-complex structures on E are automatically integrable,and holomor-phic structures on E are specified by elements of an infinite-dimensional com-plex affine space whose vector space of translations is isomorphic to the space Ω0,1(C,End(E)).The complexified gauge group G C acts on C by bundle au-tomorphisms,and isomorphism classes of holomorphic vector bundles on C are in bijection with G C-orbits in C.In modern terms,we can identify the quotient stack C/G C with the moduli stack of vector bundles on C,but to obtain a well behaved moduli space we restrict ourselves to stable bundles.LetG C acts freely on C s(which equals C ss when n and d are coprime) and the quotient space C s/G denote the quotient of G by this central subgroup;then G.There is a canonical affine linear isomorphism of the space A of unitary connections on the complex vector bundle E with the space C of holomorphic structures on E([AB83]p.570).The Yang-Mills functional on A associates6with any unitary connection A on E the integral over C of the norm square of its curvature F A.Atiyah and Bott apply the ideas of equivariant Morse theory to the Yang-Mills functional on A(or equivalently on C).Recall that the equivariant cohomology H∗G(Y)of a topological space Y on which a group G acts can be defined as the ordinary cohomology of the Borel quotient EG×G Y where EG→BG is the universal G-bundle over the classifying space BG of G.When G acts freely on Y the natural map EG×G Y→Y/G has contractiblefibres and induces an isomorphism H∗(Y/G)∼=H∗G(Y), while when Y is contractible the map EG×G Y→BG induces an isomorphism between H∗G(Y)and H∗(BG).Since C is an affine space it is contractible,and so(C)∼=H∗(B G C).H∗GCThis algebra is easy to describe explicitly:over Q it is freely generated as a polynomial algebra tensored with an exterior algebra by the K¨u nneth compo-nents of the equivariant Chern classes of the universal bundle on C×X and has Poincar´e seriesP t(B G C)def= i≥0t i dim Q H i(B G C,Q)= n j=1(1+t2j−1)2gG C acts freely on C s,the identification of smooth manifolds M(n,d)∼= C s/G C∼=C s/G C)∼=H∗(C s).G CAtiyah and Bott study the cohomology of the moduli space M(n,d)when n and d are coprime(so that C s=C ss)by showing that the restriction map(C ss)is surjective.In order to do this,they consider the H∗G CYang-Mills(or Atiyah-Bott-Shatz)stratification of C;this is a stratification of C byThe Harder-Narasimhan type of E is defined to be the decreasing sequence µ=(µ1,...,µn)of rational numbers in whichµ(gr j(E))=d j/n j appears n j times.The Yang-Mills stratum Cµis then the subset of C consisting of all holomorphic structures of Harder-Narasimhan typeµon E.Since the Harder-Narasimhanfiltration of a holomorphic vector bundle is canonically defined,the assignments E→gr j E induce a map from the space of vector bundles with afixed Harder-Narasimhan type(d1/n1,...,d r/n r)as above to the product of the spaces of bundles of degree d j and rank n j.If we let G C(n j,d j)denote the complexified gauge group of the smooth vector bundle underlying gr j E,the map just defined(together with the K¨u nneth formula) gives an isomorphism:H∗GC (Cµ)∼=rj=1H∗G C(n j,d j)(C ss(n j,d j)).(3)The unique open stratum of the Yang-Mills stratification is C ss,and when n and d are coprime we haveH∗GC(C ss)∼=H∗(B C∗)⊗H∗(M(n,d)).The complexified gauge group G C acts on C=C(n,d)preserving the Yang-Mills stratification.The Yang-Mills strata may be totally ordered so that the closure of a stratum Cµis contained in the union of lower-dimensional strata Cµ′withµ′≥µ.We let Uµdenote the open subset of C obtained by taking the union of all strata Cµ′forµ′≤µ.We can then consider the inclusion of Cµinto Uµand the associated Thom-Gysin sequence:···→H j−2cµG C (Cµ)→H jG C(Uµ)→H jG C(Uµ−Cµ)→···where cµis the codimension of the complement of Uµin C n,d.The Yang-Mills stratification is equivariantly perfect in the sense that these Thom-Gysin sequences break up into short exact sequences0→H j−2cµG C (Cµ)→H jG C(Uµ)→H jG C(Uµ−Cµ)→0.The integer cµcan be computed in terms of ranks and degrees appearing in the Harder-Narasimhan typeµ=(d1/n1,...,d r/n r):cµ= ℓ>j(nℓd j−n j dℓ+nℓn j(g−1)).(4) Atiyah and Bott show that the Yang-Mills stratification is equivariantly perfectby considering the composition of the Thom-Gysin map H j−2cµG C (Cµ)→H jG C(Uµ)with restriction to Cµ,which is multiplication by the equivariant Euler class eµof the normal bundle to Cµin C.They show that eµis not a zero-divisor inH GC (Cµ)and deduce that the Thom-Gysin maps H j−2cµG C(Cµ)→H jG C(Uµ)areall injective.8Choosing splittings of the short exact sequences above then gives the follow-ing direct sum decomposition(of rational vector spaces):H jG C(C,Q)∼= i H j−2cµG C(Cµ,Q).(5)One may derive the inductive formulas obtained by Atiyah and Bott in[AB83] for the equivariant Betti numbers of C ss n,d(and hence when n and d are coprime for the Betti numbers of M(n,d))by combining equations(3),(1)and(5).In terms of the equivariant Poincar´e seriesP G C t(X)def= i≥0t i dim Q H i G C(X,Q)they are given byP G C t(C ss)=P t(B G C)−µ=(d/n,...,d/n)P G C t(Cµ)(6) where P t(B G C)is given by(1)and ifµ=(d1/n1,...,d r/n r))then by(3)wehaveP G C t(Cµ)=rj=1P G C(n j,d j)t(C ss(n j,d j)).The case n=2.Every line bundle over C is stable,and the moduli spaces M(1,d)are topolog-ically tori C g/Z2g;we haveP t(M(1,d))=P t(B(1−t4)(1−t2)2−∞j=0t2(2j+g) (1+t)2gIt follows that when d is oddP t(M(2,d))=(1−t2)P G C(2,d)t (C ss(2,d))=(1+t)2g(1−t4)−t2g(1+t)2g(1−t2)2(1+t2)(8)which is a polynomial of degree6g−6in t if g≥2.2.2Tamagawa numbers and curves overfinitefieldsThe Weil conjecturesThe computation of the Betti numbers of the moduli spaces M(n,d)of bundles of coprime rank n and degree d over a nonsingular complex projective curve C by Atiyah and Bott was preceded by equivalent inductive formulae presented by Harder,Narasimhan,Desale and Ramanan[HN75,DR75].These compu-tations utilize the Weil conjectures,proved by Deligne,and a computation of the Tamagawa number for SL n,perhaps originally due to Siegel,but appearing explicitly in work of Weil[Wei82].Let us briefly review the setting of the Weil conjectures as it serves to motivate“motivic”ideas.Let F q be afinitefield with q elements,where q is a power of a prime p. Suppose that X is afinite type scheme over F q.Following Weil,one defines the zeta function of X as the following formal power series with rational coefficients:Z X(t)=exp(∞r=1|X(F q r)|t r q n t)=±q nEP0(t)P2(t)···P2n(t)10where P0(t)=1−t,P2n(t)=1−q n t and all the other P i(t)are polynomials with integer coefficients that can be writtenP i(t)= (1−αij t)withαij some collection of algebraic integers of norm q i/2.(The closer analogue of the Riemann zeta function isζX(s)=Z X(q−s),whose zeros and poles are on the lines Re s=j/2with j=0,1,...,2n.)Thefirst two statements of the Weil conjectures were verified(for arbitrary n)first by Dwork and later by Artin and Grothendieck using Grothendieck’s theory of´e tale cohomology.The Riemann hypothesis was later established by Deligne[Del80].LetF q obtained by base change.Let F r q denote the geometric Frobenius automorphism of¯X induced by the automorphismα→αq of(indeed projective)over B′and restricts to X over the generic point Spec L of B′.Since the morphism is generically smooth,shrinking B′if necessary we obtain a non-empty open subscheme B of SpecØL and associated morphism X→B which is both smooth and projective and which restricts to X over the generic point Spec L.Given a prime ideal p whose inclusion inØL induces a morphism SpecØL/p∼=Spec F q→B,the image is necessarily a closed point of B.The scheme-theoreticfibre X p of X→B over this closed point is the “reduction modulo p”of X.Being afibre product with Spec F q,it is necessarily an F q-scheme,and by the construction of B it is both smooth and projective. Then the degree of the polynomial P i(t)defined as above for X p is equal to the i-th Betti number of the complex variety X C obtained from X by base change via the given morphismφ∗:Spec C−→Spec L;we will abuse notation and refer to these as Betti numbers of X.Now when C is a smooth projective curve over F q,geometric invariant theory (GIT)can be used to define the moduli space M C(n,d)of stable,rank n, degree d vector bundles over C,at least for large enough q(we will review this construction in section§5).When n and d are coprime,the resulting moduli space M C(n,d)is again a smooth projective variety over F q(or a suitablefinite field extension).It is not hard to see that the topology of the moduli space M(n,d)of stable vector bundles of rank n and degree d over a compact Riemann surface(or nonsingular complex projective curve)depends only on the genus of the Riemann surface,not on its complex structure.Thus,in order to study the cohomology of M(n,d),we can begin with a smooth projective curveπ:C−→B over an open subscheme B of the ring of integers in a numberfield L֒→C.Assuming thatπadmits a section,Seshadri’s extension of GIT to general base schemes (see[Ses77])can be used to construct a moduli space of stable vector bundles of coprime rank and degree over C(see[Mar78]or[Gas97]Th´e or`e me4.3).Given a prime p for which there exists a morphism Spec F q−→B(for q a power of p)whose image we denote by p,base change produces a scheme isomorphic to the moduli scheme of stable bundles over a nonsingular projective curve C p over F q;similarly,using the inclusion of the generic point Spec L֒→B and the given map Spec C−→Spec L,base change produces a scheme isomorphic to the moduli scheme of stable bundles over a nonsingular projective curve over C.Thus the Weil conjectures allow us as above to compute the Betti numbers of M(n,d)from the numbers of points defined over F q r(for r=1,2,...)of M C(n,d)where C=C p(cf.[HN75]pp.239-242).In fact it is technically easier to work with the moduli spaces MΛ(n,d)and M CΛ(n,d)of stable vector bundles of rank n andfixed determinant line bundle Λ(of degree d);when n and d are coprime,calculating the Betti numbers of MΛ(n,d)is equivalent to calculating those of M(n,d)since the determinant map M(n,d)→M(1,d)defined by E→det(E)is afibration withfibre at Λ∈M(1,d)given by MΛ(n,d),and it induces an isomorphismH∗(M(n,d))∼=H∗(MΛ(n,d))⊗H∗(M(1,d)).Here M(1,d)is isomorphic to the Jacobian variety of C,which is an abelian12variety of dimension equal to the genus g of C .In this context,counting the number of F q r –points of M C Λ(n,d )amounts to counting isomorphism classes of stable rank n vector bundles defined over F q r on the curve C with fixed determinant line bundle Λ.Tamagawa NumbersLet C be a smooth projective curve over a finite field F q .Harder,Narasimhan,Desale and Ramanan (see [HN75,DR75])showed how to count the number of F q r -points of the moduli space M C Λ(n,d )of stable rank n degree d vector bundles over C with fixed determinant Λof degree d on C ,when n and d are coprime.In order to do this,they made use of the Tamagawa number of SL n .Let us recall the relationship between the Tamagawa number of SL n and moduli spaces of vector bundles.Suppose K =F q (C )is the function field of C .Recall that the ad`e le ring A K of K is defined as follows.If x is a closed point of C ,denote the local ring at x by O X,x .Denote the completion of the local ring at x by ˆO x and the field of fractions of ˆOx by ˆK x .Then ˆO x is a compact topological ring,and choosing a local parameter determines an isomorphism to F q r [[t ]],where r is a strictly positive integer.Similarly,ˆKx is a locally compact field isomorphic to F q r ((t )).For any finite set S of closed points of C ,we define A S to be the productA S = x ∈S ˆK x × x ∈C −SˆOx ,where on the right hand side,the notation x ∈C −S should be read “x is a closed point of C −S .”Observe that each A S is a locally compact topological ring.The sets S are partially ordered by inclusion and we let A K be the locally compact topological ring obtained by taking the colimit of the rings A S as S varies.Since SL n is defined over Spec Z ,we can consider the set SL n (A K ).This set can be equipped naturally with the structure of a locally compact topological group.Let K be the maximal compact subgroup of SL n (A K )which is the prod-uct x SL n (ˆOx )(again running over closed points of C ).The group SL n (K )can be viewed as a discrete subgroup of SL n (A K ).Let Bun SL n (F q )denote the set of isomorphism classes of vector bundles on C ,defined over F q ,with trivial determinant.The starting point for the relationship between moduli spaces of bundles over C and Tamagawa numbers was Weil’s construction of a canonical bijection:K \SL n (A K )/SL n (K )∼−→Bun SL n (F q ).Briefly,any vector bundle E on C is Zariski locally trivial.Thus,E can be trivialized at the generic point ηof C .Similarly,E can be trivialized over the formal disc Spec ˆOx for any x ∈C .Elements of SL n (A K )can then be identified with collections (E ,ϕη,{ϕx }x ∈C )consisting of a vector bundle E over C with trivial determinant,a trivialization ϕηof E at the generic point,and a trivializa-tion ϕx of E over the formal disc at every closed point x ∈C .Given an element13。

Evolution through either natural selection or genetic drift is dependent on variation at the genetic and mor-phological levels. Processes that influence the genetic structure of populations include mating systems, effective population size, mutation rates and gene flow among populations. We investigated the patterns of population genetic structure of orchids and evaluated if evolutionary processes are more likely at the indi-vidual population level than at the multipopulation/species level. We hypothesized that because orchid populations are frequently small and reproductive success is often skewed, we should observe many orchids with high population genetic substructure suggesting limited gene flow among pop-ulations. If limited gene flow among populations is a common pattern in orchids, then it may well be an important component that affects the likelihood of genetic drift and selection at the local population level. Such changes may lead to differentiation and evolu-tionary diversification.A main component in evolutionary processes is the necessary condition of isolation. The amount of gene flow among local populations will determine whether or not individual populations (demes) can evolve inde-pendently which may lead to cladogenesis. Usually one migrant per generation is sufficient to prevent populations from evolving independently from other populations when effective population sizes are large. Theoretically, if the gene flow rate, Nm (the effective number of migrants per generation; N = effective pop-ulation size, m = migration rate), is larger than two individuals per generation, then it is sufficient to pre-vent local adaptation while gene flow less than one per generation will likely result in population differen-tiation by selection or genetic drift (Merrell 1981, Roughgarden 1996). If Nm lies between one and two, there will be considerable variation in gene frequen-cies among populations (Merrell 1981). Consequently,populations will have similar genetic structure as if mating were panmictic (Nm >2). Alternatively, if gene flow is low (Nm < 1), populations will have different genetic structures that may result in evolutionary change through either adaptation to the local environ-ments via natural selection or through random effects such as genetic drift.Direct observation of gene flow can be viewed by the use of mark and recapture studies (for mobile organisms, or stained pollen) or tracking marker alle-les (paternity analysis) over a short number of genera-tions. Few orchid studies have attempted to directly observe gene flow and thus far only staining or micro-tagging pollinaria have been used (Peakall 1989, Nilsson et al.1992, Folsom 1994, Tremblay 1994, Salguero-Faría & Ackerman 1999). All these studies examined gene flow only within populations. Indirect methods for detecting gene flow are obtained from allele frequencies and are an estimate of the average long-term effect of genetic differentiation by genetic drift. The alleles are assumed to be neutral so that genetic differentiation based on these markers would be a consequence of drift rather than natural selection. Bohomak (1999) concluded that simple population genetic statistics are robust for inferring gene flow among groups of individuals.The most common approach is the degree of popula-tion differentiation at the genetic level using Wright’s F estimates on data obtained through protein elec-trophoresis or various PCR type approaches. The F statistics separate the amount of genetic variation which can be attributed to inbreeding among closely related individuals in a population: FIS is the inbreed-ing coefficient within individuals; FIT is the result of non random mating within a population and the effect of population subdivision; and a third statistic, FST, is the fixation index due to random genetic drift and the lack of panmixia among populations (Wright 1978).THE GENETIC STRUCTURE OF ORCHID POPULATIONSAND ITS EVO L U T I O N A R Y IMPORTA N C ER AYMOND L. T REMBLAY1,3&J AMES D. A CKERMAN21University of Puerto Rico – Humacao, Department of Biology, Humacao, Puerto Rico, 00791, U.S.A.2University of Puerto Rico – Río Piedras, Department of BiologyP.O. Box 23360, San Juan, Puerto Rico, 00931-3360, U.S.A.3Author for correspondence: raymond@LANKESTERIANA 7: 87-92. 2003.LANKESTERIANA SpeciesReferencesNm(W)Gst Calypso bulbosa (L.) Oakes Alexandersson & Ågren 2000 3.200.072Caladenia tentaculata TatePeakall & Beattie 19967.1010.0346Cephalanthera damasonium (Mill.) Druce Scacchi, De Angelis & Corbo 1991--5--5C ephalanthera longifolia (L.) Fritsch Scacchi, De Angelis & Corbo 1991 2.1510.104Cephalanthera rubra (L.) Rich.Scacchi, De Angelis & Corbo 19910.7610.247Cymbidium goeringii Rchb. f.Chung & Chung 1999 2.300.098Cypripedium acaule Ait.Case 19941.2710.164Cypripedium calceolus L.Case 1993, 1994 1.6310.196Cypripedium candidum Muhl. ex Willd.Case 19943.3710.069Cypripedium fasciculatum Kellogg ex S. Watson Aagaard, Harrod & Shea 1999 6.000.04Cypripedium kentuckiense C. F. Reed Case et al.1998 1.1210.182Cypripedium parviflorum Salisb.var. pubescens (Willd.) O. W. Knight Case et al.19981.2810.163Southern populations Wallace & Case 20000.940.209Northern populations1.570.137var. makasin (Farw.) Sheviak 1.000.199var parviflorum 1.430.149species level0.830.232Cypripedium reginae WalterCase 19940.4710.349Dactylorhiza romana (Sebastiani) SoóBullini et al.2001 3.3210.07Dactylorhiza sambucina (L.) SoóBullini et al.20011.3110.16Epidendrum conopseum R. Br.Bush, Kutz & Anderton 19991.4330.149Epipactis helleborine (L.) Crantz Scacchi, Lanzara & De Angelis 19877.310.033European populations Squirrell et al., 20011.0010.2000.241,40.5064North AmericanHollingsworth & Dickson 19970.09042.5310.2400.791Epipactis youngiana Richards & Porter Harris & Abbott 1997 2.4310.093Eulophia sinensis Miq.Sun & Wong 2001---0.00.1331,30.6533Gooyera procera Ker-Gawl.Wong & Sun 19990.22110.5230.3971,30.3863Gymnadenia conopsea (L.) R. Br.Scacchi & De Angelis 19900.28010.471Gymnadenia conopsea (L.) R. Br. conopsea Soliva & Widmer 19992.960.078Gymnadenia conopsea (L.) R. Br.subsp densiflora (Wahl) E.G. Camus & A. Camus Soliva & Widmer 19990.390.391Lepanthes caritensis Tremblay & Ackerman Carromero, Tremblay & Ackerman 1.300.167(unpublished)Lepanthes rupestris Stimson Tremblay & Ackerman 2001 1.840.170Lepanthes rubripetala Stimson Tremblay & Ackerman 20010.620.270Lepanthes eltoroensis Stimson Tremblay & Ackerman 20010.890.220Lepanthes sanguinea Hook.Carromero, Tremblay & Ackerman 1.450.144(unpublished)Table 1. Estimates of gene flow in orchids. Nm(W) = gene flow estimates based on Wright’s statistics; Gst coeff-cient of genic differentiation among populations. 1Nm calculated by the present authors from Gst or Fst using formula on p. 320 of Hartl & Clark (1989). 2Recalculated using previous formula, original Nm value 3.70. 3Calculated from RAPD markers. 4Calculated from cpDNA. 5No genetic differentiation found among populations. 6Calculated according to Weir and Cockerham’s statistics. 7. Estimated using RAPD’s and AMOVA.88Nº 7T REMBLAY&A CKERMAN- Genetic structure of orchid populationsConsequently, if we make the assumption that the genetic markers sampled are neutral or nearly neutral and that the observed level of FST is a measure of the current gene flow among populations (rather than a historical remnant), then we can evaluate the likelihood that populations are effectively isolated. The scale of FST is from 0 (no population subdivision) to 1.0 (com-plete genetic differentiation among populations).We gathered population genetic data for 58 species of terrestrial and epiphytic orchids from temperate and tropical species. The data are biased toward ter-restrial/temperate species (N = 44). We found only three studies of terrestrial/tropical species and ten epi-phytic/tropical. There is also a bias toward certain taxa: Orchis, Cypripedium, Pterostylis and Lepanthes account for nearly half (30) of the 61 records (Table 1), 10 species of O r c h i s, 7 species each of Cypripedium and Pterostylis, 6 species of Lepanthes,3 species of S p i r a n t h e s, Epipactis, Cephalantheraa n d G y m n a d e n i a, 2 species of D a c t y l o r h i z a, Epipactis, Vanilla and Zeuxine, and one species each of Caladenia, Calypso, Cymbidium, Epidendrum, Eulophia, Goodyera, Nigritella, Paphiopedilum, Platanthera, Tipularia, and Tolumnia.89Mayo 2003Gene flow among populations varies among species ranging from a high of 12 effective migrants per gen-eration in Orchis longicornu(Corrias et al. 1991) to lows of less then 0.2 in Zeuxine strateumatica(Sun & Wong 2001). Assembling the species in groups based on their estimates of gene flow, we note that 18 species have less then one migrant per generation, while 19 species have more than two migrants per generation, and 17 of the species have a migration rates between one and two. No genetic differentiation was found among populations for C e p h a l a n t h e r a d a m a s o n i u m(Scacchi, De Angelis & Corbo 1991) and Spiranthes hongkongensis(Sun 1996). Consequently these two species are excluded from further analysis.O r c h i s species typically have high estimates of gene flow among populations (Scacchi, De Angelis & Lanzara 1990, Corrias et al. 1991, Rossi et al. 1992) whereas Lepanthes and Pterostylis species have much lower gene flow estimates (Tremblay & Ackerman 2001, Sharma, Clements & Jones 2000; Sharma et al.2001). However even within a genus variation in gene flow can be extensive (Table 1).Are there phylogenetic associations with gene flow? The data for O r c h i s(mean Nm = 5.7), L e p a n t h e s(mean Nm = 2.1) and P t e r o s t y l i s( m e a n Nm = 1.0) are suggestive, but much more extensive sampling is needed for both temperate and tropical species. Curiously, L e p a n t h e s and O r c h i s have very different population genetic parameters yet both are species-rich genera and are likely in a state of evolu-tionary flux. It seems to us that orchids have taken more than one expressway to diversification. For the group of species which has more than 2 migrants per generation local populations will not evolve indepen-dently, but as a group, consequently local morpholog-ical and genetic differences among groups will be wiped out, and populations will become homoge-neous if gene flow continues at the level. When gene flow is high, selection studies from different popula-tions should be evaluated together (Fig. 1).For populations that have less than one migrant perLANKESTERIANAFigure 1: Distribution of mean (s.e.) gene flow (Nm) among genera of Orchids. Bars without error bars of single datap o i n t s.90Nº 7T REMBLAY&A CKERMAN- Genetic structure of orchid populationsgeneration, local populations can evolve independent-ly, and evolutionary studies should be done at the local level. In small populations, we may expect genetic drift to be present and selection coefficients should be high to counteract the effects of drift.For species with intermediate gene flow it is proba-bly wise to evaluate evolutionary processes at the local and multi-population/species level. We expect variance in migration rates to be large because of the skewed reproductive success among individuals, time periods and populations. Consequently, the outcome of the evolutionary process will likely depend on the amount and variation of the migration events and consistency in migration rates in time. If variance in gene flow through space and time is small, then the genetic dif-ferentiation will be more or less stable. But, for exam-ple, if variance in gene flow is high, with some periods having high gene flow followed by little or no gene flow for an extended period of time, it is possible that through natural selection and genetic drift local popula-tions might differentiate sufficiently for cladogenesis during the period of reduced immigration.Species with less than one migrant per population are basically unique evolutionary units evolving inde-pendently from other local populations. In popula-tions with large Ne (> 50), it is likely that natural selection will dominate evolutionary processes while if Ne is small (< 50) genetic drift and selection can both be responsible for evolution. Consequently for these species, local adaptation to specific environ-mental conditions is possible.This survey of population genetics studies of orchids shows that multiple evolutionary processes have likely been responsible for the remarkable diver-sification in orchids.L ITERATURE C ITEDAagaard J.E., R.J. Harrod & K.L. Shea. 1999. Genetic vari-ation among populations of the rare clustered lady-slip-per orchid (Cypripedium fasciculatum) from Washington State, USA. Nat. Areas J. 19: 234-238Ackerman J.D. & S. Ward. 1999. Genetic variation in a widespread epiphytic orchid: where is the evolutionary potential? Syst. Bot. 24: 282-291.Alexandersson, R. & J. Ågren. 2000. Genetic structure of the nonrewarding bumblebee pollinated Calypso bul-bosa. Heredity 85: 401-409Arduino, P., F. Verra, R. Cianchi, W. Rossi, B. Corrias, & L. Bullini. 1996. Genetic variation and natural hybridization between Orchis laxiflora and O r c h i s palustris(Orchidaceae). Pl. Syst. Evol. 202: 87-109. Arft, A.M. & T.A. Ranker. 1998. Allopolyploid origin and population genetics of the rare orchid Spiranthes diluvi-alis. Am. J. Bot. 85: 110-122.Bohomak, A.J. 1999. Dispersal, gene flow, and population structure. Quart. Rev. Biol. 74: 21-45.Bullini, L., R. Cianchi, P. Arduino, L. De Bonis, M. C. Mosco, A. Verdi, D. Porretta, B. Corrias & W. Rossi. 2001. Molecular evidence for allopolyploid speciation and a single origin of the western Mediterranean orchid Dactylorhiza insularis(Orchidaceae). Biol. J. Lin. Soc. 72: 193-201.Bush, S.T., W.E. Kutz & J.M. Anderton. 1999. RAPD variation in temperate populations of epiphytic orchid Epidendrum conopseum and the epiphytic fern Pleopeltis polypodioides. Selbyana 20: 120-124. Case, M.A. 1993. High levels of allozyme variation within Cypripedium calceolus(Orchidaceae) and low levels of divergence among its varieties. Syst. Bot. 18: 663-677. Case, M.A. 1994. Extensive variation in the levels of genetic diversity and degree of relatedness among five species of Cypripedium(Orchidaceae). Amer. J. Bot. 81: 175-184.Case, M.A., H.T. Mlodozeniec, L.E. Wallace & T.W. Weldy. 1998. Conservation genetics and taxonomic sta-tus of the rare Kentucky Lady’s slipper: C y p r i p e d i u m k e n t u c k i e n s e(Orchidaceae). Amer. J. Bot. 85: 1779-1779.Chung, M.Y. & M.G. Chung. 1999. Allozyme diversity and population structure in Korean populations of Cymbidium goeringii(Orchidaceae). J. Pl. Res. 112: 139-144.Corrias, B., W. Rossi, P. Arduino, R. Cianchi & L. Bullini. 1991. Orchis longicornu Poiret in Sardinia: genetic, morphological and chronological data. Webbia 45: 71-101.Folsom, J.P. 1994. Pollination of a fragrant orchid. Orch. Dig. 58: 83-99.Harris, S.A. & R. J. Abbott. 1997. Isozyme analysis of the reported origin of a new hybrid orchid species, Epipactis y o u n g i a n a(Young’s helleborine), in the British Isles. Heredity 79: 402-407.Hedrén, M., E. Klein & H. Teppner. 2000. Evolution of polyploids in the European orchid genus N i g r i t e l l a: Evidence from allozyme data. Phyton 40: 239-275. Hollingsworth, P.M. & J.H. Dickson. 1997. Genetic varia-tion in rural and urban populations of Epipactis helle-b o r i n e(L.) Crantz. (Orchidaceae) in Britain. Bot. J. Linn. Soc. 123: 321-331.Li, A, Y., B. Luo & S. Ge. 2002. A preliminary study on conservation genetics of an endangered orchid (Paphiopedilum micranthum) from Southwestern China. Bioch. Gen. 40: 195-201.Merrell, D.J. 1981. Ecological Genetics. University of Minnesota Press, Minneapolis, Minnesota.Nielsen, L.R. & H.R. Siegismund. 2000. Interspecific dif-ferentiation and hybridization in V a n i l l a s p e c i e s (Orchidaceae). Heredity 83: 560-567.91Mayo 2003LANKESTERIANANilsson, L.A., E. Rabakonandrianina & B. Pettersson. 1992. Exact tracking of pollen transfer and mating in plants. Nature 360: 666-667.Peakall, R. 1989. A new technique for monitoring pollen flow in orchids. Oecologia 79: 361-365.Peakall, R. & A. J. Beattie. 1996. Ecological and genetic consequences of pollination by sexual deception in the orchid Caladenia tentaculata. Ecology 50: 2207-2220. Rossi, W., B. Corrias, P. Arduino, R. Cianchi & L. Bullini L. 1992. Gene variation and gene flow in Orchis morio (Orchidaceae) from Italy. Pl. Syst. Evol. 179: 43-58. Roughgarden, J. 1996. Theory of population genetics and evolutionary ecology: An Introduction. Prentice Hall, Upper Saddle River, NJ, USA.Salguero-Faría, J.A. & J.D. Ackerman. 1999. A nectar reward: is more better? Biotropica 31: 303-311. Scacchi, R., G. De Angelis & R.M. Corbo. 1991. Effect of the breeding system ion the genetic structure in C e p h a l a n t h e r a spp. (Orchidaceae). Pl. Syst. Evol. 176: 53-61.Scacchi, R., G. De Angelis & P. Lanzara. 1990. Allozyme variation among and within eleven Orchis species (fam. Orchidaceae), with special reference to hybridizing apti-tude. Genetica 81: 143-150.Scacchi, R. and G. De Angelis. 1990. Isoenzyme polymor-phisms in G y m n a e d e n i a[sic] c o n o p s e a and its infer-ences for systematics within this species. Bioch. Syst. Ecol. 17: 25-33.Scacchi, R., P. Lanzara & G. De Angelis. 1987. Study of electrophoretic variability in Epipactis heleborine ( L.) Crantz, E. palustris(L.) Crantz and E. microphylla (Ehrh.) Swartz (fam. Orchidaceae). Genetica 72: 217-224.Sharma, I.K., M.A. Clements & D.L. Jones. 2000. Observations of high genetic variability in the endan-gered Australian terrestrial orchid Pterostylis gibbosa R. Br. (Orchidaceae). Bioch. Syst. Ecol. 28: 651-663. Sharma, I.K., D.L. Jones, A.G. Young & C.J. French. 2001. Genetic diversity and phylogenetic relatedness among six endemic P t e r o s t y l i s species (Orchidaceae; series Grandiflorae) of Western Australia, as revealed by allozyme polymorphisms. Bioch. Syst. Ecol. 29: 697-710.Smith, J.L., K.L. Hunter & R.B. Hunter. 2002. Genetic variation in the terrestrial orchid Tipularia discolor. Southeastern Nat. 1: 17-26Soliva, M. & A. Widmer A. 1999. Genetic and floral divergence among sympatric populations of Gymnadenia conopsea s.l. (Orchidaceae) with different flowering phenology. Int. J. Pl. Sci. 160: 897-905. Squirrell, J., P.M. Hollingsworth, R.M. Bateman, J.H. Dickson, M.H.S. Light, M. MacConaill & M.C. Tebbitt. 2001. Partitioning and diversity of nuclear and organelle markers in native and introduced populations of Epipactis helleborine(Orchidaceae). Amer. J. Bot. 88: 1409-1418.Sun, M. 1996. Effects of Population size, mating system, and evolution origin on genetic diversity in S p i r a n t h e s sinensis and S. hongkongensis. Cons. Biol. 10: 785-795. Sun, M. & K.C. Wong. 2001. Genetic structure of three orchid species with contrasting breeding system using RAPD and allozyme markers. Amer. J. Bot. 88: 2180-2188.Tremblay, R.L. 1994. Frequency and consequences of multi-parental pollinations in a population of Cypripedium calceolus L. var. pubescens(Orchidaceae). Lindleyana 9: 161-167.Tremblay, R.L & J.D. Ackerman. 2001. Gene flow and effective population size in Lepanthes(Orchidaceae): a case for genetic drift. Biol. J. Linn. Soc. 72: 47-62. Wallace, L.A. 2002. Examining the effects of fragmenta-tion on genetic variation in Platanthera leucophaea (Orchidaceae): Inferences from allozyme and random amplified polymorphic DNA markers. Pl. Sp. Biol 17: 37-39.Wallace, L.A. & M. A. Case. 2000. Contrasting diversity between Northern and Southern populations of Cypripedium parviflorum(Orchidaceae): Implications for Pleistocene refugia and taxonomic boundaries. Syst. Bot. 25: 281-296.Wong, K.C. & M. Sun. 1999. Reproductive biology and conservation genetics of Goodyera procera (Orchidaceae). Amer. J. Bot. 86: 1406-1413.Wright, S. 1978. Evolution and the genetics of popula-tions. Vol. 4. Variability within and among natural pop-ulations. Chicago, The University of Chicago Press.Raymond L. Tremblay is an associate professor at the University of Puerto Rico in Humacao and the graduate faculty at UPR- Río Piedras. He obtained his B.Sc. with Honours at Carleton University, Ottawa, Canada in 1990 and his PhD at the University of Puerto Rico in Rio Piedras in 1996. He is presently the chairman of the In situ Orchid Conservation Committee of the Orchid Specialist Group. He is interested in evolutionary and con-servation biology of small populations. Presently his interest revolves in determining the life history characters that limit population growth rate in orchids and evaluating probability of extinction of small orchid populations. James D. Ackerman, Ph.D., is Senior Professor of Biology at the Univesrity of Puerto Rico, Río Piedras. He is an orchidologist, studying pollination an systematics.92Nº 7。

最小臨床重要差異(minimal clinically important difference, MCID) 簡介引言：MCID 的主要功能是協助研究及臨床人員解釋評量分數變化或差異之意義。

研究上，療效的判斷常以是否「統計顯著(statistical significance)」判定之，然而具有統計顯著之差異值，不一定具有「臨床意義(clinical significance)」。

MCID值可作為判斷群組分數改變/差異（組內(within-group)/組間(between-group)）是否具有臨床重要意義的最小閾值，決定評量工具的MCID 值，可協助臨床及研究人員判斷研究結果所造成的差異是否具備「臨床意義」！MCID值的另一用途是判斷評估工具是否具備反應性(responsiveness)(within-group)。

以下舉例說明：1. Fey et al. (Stroke. 2004;35:924-9.) 的研究中，實驗組與對照組病人的前測Barthel index (BI) 中位數分數分別為8分及10分，統計分析顯示二組(between-group)的差異「不顯著」(P=0.21)。

作者宣稱”No significant difference was found.” Davidson et al. (Clin Rehabil. 2005;19:126-37.) 亦發現其研究中實驗與對照二組間的前測差異為3.5分，但不顯著(P=0.18)。

試問2分或3.5分的差異，皆不大嗎？具有「臨床意義」嗎？2. Iwasaki et al. (J Clin Psychiatry. 2005;66:248-52.)發現實驗組病人(within-group)的BI分數由11.3顯著進步至12.6 分(P<0.05)。

作者因而宣稱”xxx improves ADL.”另外Clark et al. (Clin Rehabil. 2003;17:703-12.) 發現"… slightly better functional recovery in the intervention group (mean BI difference1.3) (P < 0.05)."但1.3分的進步量，具有「臨床意義」嗎？3. Hsueh et al. (J Formos Med Assoc. 2001;100:526-32.)發現BI於中風發病90-180天期間具有”low responsiveness (mean change score=0.26, effect sized=0.11, SRM=0.28, p=0.026)”。

吉林柳河县2016高考英语（二轮）阅读理解选练（1）及答案2016高考训练题■…阅读理解。

阅读下列短文，从每题所给的四个选项（A、B、C、D）中，选出最佳选项。

Dear Miss Manners, When an ice cube melts, it creates a puddle （水坑）.When an ice sheet （冰盖）melts, it raises sea levels. It sounds simple，but scientists have debated for decades whether both the Antarctic and Greenland ice sheets actually were shrinking, and how much that melting contributed to rising sea levels.Now, a new study has provided the best evidence of how the polar ice sheets are responding to our warming world. In the study, An international team of scientists looked at 20 years of data in the icc sheets collected by 10 satellite missions. The team's conclusion: The Greenland and Antarctic icc sheets both are losing ice overall. The researchers also found that between 1992 and 2011, meltwater from those shrinking ice sheets caused sea levels to rise by about 11 millimeters.Over the 19 years studied, the Greenland ice sheet lost 2.7 trillion metric tons of ice. The Antarctic ice sheet also shrank by about 1.3 trillion metric tons・ Previously, some scientists disagreed whether the Antarctic sheet, the largest mass of icc in the world, was shrinking or growing or neither.While the Earth is wanning overall, the effect of climate change varies from region to region. Over the last 15 years, for example, scientists have something disagreed over how climate change has affected the polar ice sheets. Many studies found that the sheets lost a lot of ice and that not enough snow fell on the sheets to compensate fdir the loss. But other studies found that the loss of ice was balanced by the gain in snowfall・Richard Alley, a glacier scientist at Penn State University, said that many of those studies looked at different areas, and over different time periods. In addition, the studies didn't all use the satellite data in the same way. Those differences made it difficult to compare the results.The data in the new study matched time periods and areas・ The study also combined measurements from kinds of satellites.12.Why does the author use a common-sense phenomenon as the beginning?A.To present the reason for ice sheet melting・B.To show us the result of a scientific experiment.C.To give a simple example to introduce the topic.D.To present a common daily finding obvious to the readers.13.The researchers reached their conclusion by ____ ・A.analyzing the findings of former studiesB.referring to the data from satellitesC.observing the Antarctic and GreenlandD.making measurements in the Antarctic and Greenland14.What does the underlined phrase ”compensate for11 in paragraph 4 refer to?A.Cut down. B・ Lead to. C. Bring about. D. Make up fdr.15.Which of the following might be the best conclusion for the passage?A.Ice sheets are shrinking due to global warming.B.People are suffering from climate change.C.Rising sea levels makes people live in danger.D.Shrinking ice has nothing to do with sea levels.参考答案12-15、CBDA阅读理解。

广东省2025届普通高中毕业班第一次调研考试英语本试卷共8页，考试用时120分钟，满分120分。

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第二部分阅读（共两节，满分50分）第一节（共15小题；每小题2.5分，满分37.5分）阅读下列短文，从每题所给的A、B、C、D四个选项中选出最佳选项。

ATICKJETS FOR KENSINGTON PALACJE AND UNTOJLJD JLIVESKensington Palace TicketsAn admission ticket includes access to all public areas of the palace and gardens including: Untold Lives exhibition, Victoria:A Royal Childhood, The King's State Apartments and The Queen’s State Apartments.（续表）How to Get Tickets You've Bought OnlineDownload your PDF ticket to your mobile for scanning(扫描) at the entrance or click the link in the email that we’ll send you and print out all your tickets.If you are not able to download your e-tickets using the link in your confirmation email, please show your reference number which begins 42xxxxxxxxx to the ticket desk when you arrive and staff on site will be able to print your tickets for you.21. What can a Kensington Palace ticket be used to do?A. Serve as an identification card.B. Provide discounts for kid tickets.C. Offer free visit to several places.D. Show how to print online tickets.22. How much should a class of 20 pupils and a teacher pay for the entry?A. About ￡21.B. About￡264.C. About ￡404.D. About￡464.23. What is needed when you have your tickets printed on site?A. The cellphone screen.B. The reference number.C. The ticket price table.D. The confirmation email.BAs a college professor, I am required to hold an office hour before my lecture. These office hours are optional and tend to be busier at the beginning and end of a semester(学期).In the middle, they can become quiet. A few years ago I was given a flute(长笛) as a gift, so I decided that I would use my quiet office hours to practice this new instrument. The experience brought unexpected insights into performance anxiety.I held my office hour in the near-empty lecture hall, one hour before the class began. The hall was open to any student who wished to talk with me about coursework or to take a seat and quietly read before the lecture began. I would assemble (组装) my flute, open my lesson book, and begin working on the instrument I had never played before. I also followed online video lesson s－a ll done in front of a few students who would come early to class.I would begin playing l ong tones, closing my eyes and “forgetting” that anyone was in the room with me. I was surprised to find that I felt no anxiety while learning a new instrument in front of others. Had I been playing my main instrument, I would have had more concern about the level of my playing and how my playing was being received. However, in this setting, it was clear that I was an absolute beginner with no expectations of impressing anyone with my mastery. My attention was set on figuring the instrument out. I had no expectations of how I would sound and had little expectations of sounding like anything more than a beginner.There have been many things I have learned from my experiment of learning an instrument in public. Whenever musicians talk with me about their stage fright, I offer them this story.24. What is “an office hour” for?A. The professors to show talents.B. The students to appreciate music.C. The teachers to offer consultation.D. The lecturers to make preparations.25. Why did the author play a flute?A. To pass the time.B. To give a lecture.C. To do a research.D. To attract students.26. What made the author at ease when playing the flute?A. The technique from the video.B. His impressive performance.C. The audience’s active response.D. His concentration on playing.27. Which of the following is a suitable title for the text?A. My Joy of Learning a New ThingB. My Tip on Performing in the PublicC. My Discovery to Ease Stage FrightD. My Office Hour Before Every LessonCAs AI develops, it becomes challenging to distinguish between its content and human-created work. Before compar ing both, it’s good to know about the Perplexity & Burstiness of a text.Perplexity is a measurement used to evaluate the performance of language models in predicting the next word in a group of words. It measures how well the model can estimate the probability of a word occurring based on the previous context. A lower perplexity score indicates better predictability and understanding of the language, while a higher perplexity score suggests a higher degree of uncertainty and less accurate predictions. The human mind is so complex compared to current AI models that human-written text has high perplexity compared to AI-generated text.Examples :High Perplexity: “The teapot sang an opera of hot, wheeling tea, every steamy note a symphony of flavor. ”Low Perplexity: “I poured hot water into the teapot, and a fresh smell filled the room. ”Burstiness refers to the variation in the length and structure of sentences within a piece of content. It measures the degree of diversity and unpredictability in the arrangement of sentences. Human writing often exhibits bursts and lulls (间歇) , with a mix of long and short sentences, while AI-generated content tends to have a more uniform and regular pattern. Higher burstiness indicates greater creativity, spontaneity (自发性) , and engagement in writing, while lower burstiness reflects a more robotic and monotonous (单调的) style. Just like the perplexity score, human-written content usually has a high burstiness score.Examples :High Burstiness: “The alarm screamed. Feet hit the floor. The tea kettle whistled. Steam streamed. Heart pounded. The world, awake. ”Low Burstiness: “In the peaceful morning, the alarm clock’s soft ring greeted a new day. I walked to the kitchen, my steps light and unhurried. The tea kettle whistled its gentle song, a comforting tune that harmonized with the steam’s soft whisper. ”Here, I wrote a passage on the “Importance of l ifelong learning”myself and also asked ChatGPT to do the same to compare better AI-generated and human-written text.28. What do Perplexity & Burstiness probably serve as?A. Complexities of a language.B. Criteria on features of a text.C. Phenomena of language varieties.D. References in generating a text.29. What are the characteristics of an Al-generated text?A. Low perplexity and low burstiness.B. High perplexity and low burstiness.C. Low perplexity and high burstiness.D. High perplexity and high burstiness.30. Which of the writing ways below does the author skip when developing the article?A. Quoting sayings.B. Showing examples.C. Giving definitions.D. Making comparisons.31. What will be probably talked about next?A. Some essays from ChatGPT.B. An illustration for differences.C. An example of the writer’s own.D. Analyses of lifelong learning.DWhen stressed out, many of us turn to junk food like deep-fried food for comfort. But a new research suggests this strategy may backfire. The study found that in animals, a high-fat diet disrupts resident gut bacteria (肠道细菌) , changes behavior and, through a complex pathway connecting the gut to the brain, influences brain chemicals in ways chat fuel anxiety.“Everyone knows that these are not healthy foods, but we tend to think about them strictly in terms of a little weight gain,”said lead author Christopher Lowry, a professor of integrative physiology at CU Boulder. “If you understand that they also impact your brain in a way that can promote anxiety, that makes the risk even higher.”Lowry’s team divided mice into two groups: Half got a standard diet of about 11% fat for nine weeks; the others got a high-fat diet of 45% fat, consisting mostly of fat from animal products. The typical American diet is about 36% fat, according to the Centers for Disease Control and Prevention.When compared to the control group, the group eating a high-fat diet, not surprisingly, gained weight. But the animals also showed significantly less diversity of gut bacteria. Generally speaking, more bacterial diversity is associated with better health, Lowry explained. The high-fat diet group also showed higher expression of three genes（基因）（tph2, htrla, and slc6a4) involved in production and signaling of the brain chemical called serotoni n－particularly in a region of the central part of the brain known as the dorsal raphe nucleus cDRD, which is associated with stress and anxiety. While serotonin is often billed as a “feel-good brain chemical”, Lowry notes that certain subsets of serotonin neurons（神经元）can, when activated, touch off anxiety-like responses in animals. Especially, heightened expression of tph2 in the cDRD has been associated with mood disorders in humans.“To think that just a high-fat diet could change expression of these genes in the brain is extraordinary,” said Lowry.“The high-fat group essentially had a high anxiety state in their brain. ” However, L owry stresses that not all fats are bad, and that healthy fats like those found in fish, nuts and seeds can be good for the brain.32. What is山e new finding?A. Junk food leads to overweight.B. High-fat food brings bad moods.C. Brain chemicals cause anxiety.D. Gut bacteria benefit brain health.33. What does the underlined word “disrupts” in paragraph l mean?A. Upsets.B. Facilitates.C. Loosens.D. Generates.34. How were the mice eating a high-fat diet by contrast with the control group?A. They looked more anxious.B. They lost much more weight.C. They suffered mood disorders.D. They lacked gut bacteria variety.35. What does Lowry agree with?A. Every fat is harmful.B. Fish fat is harmless.C. Stress comes from fat.D. Some fats are good.第二节（共5小题；每小题2.5分，满分12.5分）阅读下面短文，从短文后的选项中选出可以填入空白处的最佳选项。

湖北省新高考协作体2024-2025学年高三上学期11月期中英语试题一、阅读理解If you are planning to start a career in the field of education, science, or culture, then an internship (实习) at UNESCO will be ideal for you.Who can apply?● You have completed your full-time university studies: or● You are studying in a graduate program for a master’s degree.● Applicants in technical assignments must have reached the last year of their studies in a technical institution.What are the requirements?● You must be at least 20 years old.● You should have a good command of either English or Chinese.● You must have an excellent knowledge of office-related software.● You should be able to work well in a team and adapt to an international working environment.● You should possess strong interpersonal and communication skills.What do you need to prepare?● Visa: You should obtain the necessary visas.● Travel: You must arrange and finance your travel to and from the location where you will do your internship.● Medical insurance: You must show proof of a comprehensive health insurance valid in the target country for the entire period of the internship. UNESCO will provide limited insurance coverage up to USD30,000 for the internship period.● Medical certificate: You must provide a medical certificate indicating you are fit to work.● Motivation letter: You should have your motivation letter ready before filling in the application form.Your application will be accessed by UNESCO managers and will stay in our database forsix months. We do not respond to every candidate. If selected, you will be contacted by a manager to attain more details. If you do not receive any update within six months, it means that your application has not been successful. For more information, please contact us on . 1．What requirements should the applicants meet?A．Having international study experience.B．Holding a master’s degree in education.C．Being fluent in either English or French.D．Doing well in interacting and communicating with people.2．What will the applicants not need to prepare?A．A necessary visa for the internship.B．A medical certificate for the internship.C．A personal resume for the internship.D．A motivation letter for the internship.3．Where is this text probably taken from?A．A textbook.B．An official website.C．A travel guide.D．An academic article.Many concepts that are central to the human experience are abstract, such as relationships, ideas. and time — things we can’t directly see or touch. We commonly use concrete language to talk and think about these things, often through metaphors (隐喻).Using metaphors is far more than a poetic device of factual statements. A study conducted at Purchase College found that metaphors can frame people’s perspectives, thereby shaping their reasoning and subsequent actions. For example, describing the effort to stop climate change as a “war” rather thana “race” caused people to feel more urgency about reducing emissions.Another example is the lightbulb (灯泡) metaphor commonly used to describe new ideas, suggesting that new thoughts appear suddenly like a light switch being turned on. However, this metaphor implies that new ideas come effortlessly and are accessible only to a select few geniuses, such as Isaac Newton, who supposedly developed his theory of gravity from a sudden insight about a falling apple. It may lead people to question their capability to generate news ideas, and as a behavioral consequence, people may underestimate the role of hard work and continuouslearning in bringing about change.An alternative way to describe ideas is by comparing new thoughts to seeds that fall on fertile ground and — if cared for — will grow and develop over time. Different from the lightbulb metaphor, the seed metaphor implies an understanding that generating new ideas is a laborious process, which requires time and effort. It also suggests that anybody can be the cultivator of ideas as long as they put their mind to it.The subtle effects of metaphors show how powerful language can be, even though we often don’t realize it. Who’d have thought a simple use of a lightbulb metaphor could profoundly affect how we understand the concept of innovation? Given the nature of our metaphorical minds, it is worth asking: are our metaphors suitable? We owe it to ourselves and others to use metaphors appropriately. These choices — conscious or not — can be constructive or destructive.4．What can we know about metaphors according to the study?A．They may lead to conflicts between people.B．They can shape people’s minds and behavior.C．They make language more poetic and meaningful.D．They contribute to clarify abstract concepts further.5．Why does the author mention Isaac Newton in Paragraph 3?A．Because Isaac Newton invented the lightbulb.B．Because celebrities are more popular with people.C．Because the author means to explain the lightbulb metaphor further.D．Because the author intends to show the lightbulb metaphor is superior to the seed metaphor. 6．What is the distinguishing feature of the seed metaphor?A．It indicates consistent efforts of individuals.B．It emphasizes the importance of natural talent.C．It leads to people’s doubt about their own creativity.D．It undervalues the part of people’s hard work in causing changes.7．What is the purpose of the last paragraph?A．To present the potential limitations of metaphors.B．To reveal the difficulty of understanding metaphors.C．To urge people to reflect on the strengths of metaphors.D．To call on people to use metaphors properly in daily work and life.Paris embraces the Olympic spirit with a burst of creativity, as nearly 30 colorful street art pieces have transformed the city into an open-air gallery. These artworks, capturing scenes such as the dynamic French fencer Ysaora Thibus and the calm boaters on the Seine River, have made a lasting impression on people.Street artists come from different countries. Their pieces not only capture the essence of Parisian life, from the busy coffee shops to the charming bookstores, but also extend to airports in Lille, Lyon, and Marseille. These cities are co-hosting some of the Olympic events. Street art bridges the gap between high culture and everyday life, making art accessible to everyone. It promotes shared appreciation, inspiring conversations in public spaces like subway stations and airports and encouraging interaction among people of different backgrounds.The Olympics follow strict guidelines and show national spirit, while street art is freer and shows many different cultures from the community. Despite their differences, both the Olympic spirit and the world of art share a common platform of values that celebrate the pursuit (追求) of excellence, encouraging individuals to reach their highest potential. Creativity and innovation are central to both, driving artists to create with every brushstroke and athletes to excel in every performance as they both explore new heights of achievement.Art competitions first appeared at the Olympics in 1912 in Stockholm, with medals awarded in five categories: architecture, literature, music, painting and sculpture. However, the International Olympic Committee ended the competitions in the 1948 Games. Now, the spirit of the Olympics is reflected in the street art that brightens every corner of Paris. “Artists are like athletes. They also require a lot of effort and determination.” said JonOne, who is a pioneer of street art. “I respect athletes in basketball and runners. Art is not really a sport, but it should be included in the Olympics. Just surviving as an artist is an Olympic sport.”8．What can be inferred from Paragraph 2?A．All the Olympic events are held in Paris.B．Street art encourages cooperation between artists.C．Street art contributes to strengthening social connection.D．Street artists come to France to participate in the Olympic events.9．What do we know about the Olympics and street art according to the passage?A．They have strict standards to follow.B．They reflect the creativity of communities.C．They don’t attach importance to creativity or innovation.D．They not only have differences but also have common points.10．Which of the following statements will JonOne agree with?A．Athletes are easier to gain success than artists.B．People should integrate art with the Olympic Games.C．Athletes deserve more respect from people than artists.D．Art motivates many Olympic athletes to pursue their full potential.11．What is the best title for the text?A．Street Art Adds Color To the Olympics.B．Street Art Centers Around Olympic Events.C．The Olympics Bring Art Into People’s Daily Life.D．The Olympic Games Globalize Street Artists’ Fame.Some of the world’s most important scientists think the idea of people living on the Mars will come true one day. Stephen Hawking believed that humans must move into space to survive. “Once we spread out into space and establish independent resident areas, our future should be safe.” he said. Robert Zubrin, a rocket scientist, agrees and thinks starting with Mars makes the most sense. He thinks sending people to Mars will allow us to learn a lot — for example, about the ability of humans to live in a very different environment.However, scientists will need to terraform Mars for people to be able to live. Then why and how can we terraform Mars? One of the main goals of terraforming Mars is to warm it up because the average temperature there is about — 60 degrees centigrade. One idea for warming Mars is to build factories there that produce green gases. This could take many centuries. However, it should lead to rainfall and the growth of plants, resulting in more air that people can breathe.Another big concern for scientists is whether humans can move to Mars and still stay healthy in mind and body. As a test, six people lived in a Mars-like environment in Hawaii for a year before “returning to Earth” recently. It was a 1,200-square-foot room that was on the side of avolcano and used the sun for energy. Christian e Heinicke, one of the people who lived there, said that one of the biggest issues was feeling bored. So humans on Mars would always need to keep themselves busy with various activities. Another important finding was that people living together should be able to get along and work together.One particular organization based in Europe is planning to send the first humans to Mars before2030. The organization believes that its project is giving people worldwide the chance to be part of the first human crew ever to live on Mars for good. However, many experts think the project’s cost of USS6 million is too low for it to be successful. The American space agency NASA believes that sending people to Mars would cost about USS100 million, although this estimate is based on bringing them back to Earth, too. Regardless, it seems that humans living on Mars may well happen a lot sooner than most people believe.12．What’s Robert Zubrin’s attitude to humans living on Mars?A．Skeptical.B．Ambiguous.C．Favourable.D．Intolerant. 13．What does the underlined word “terraform” mean?A．Building homes on the planet.B．Transforming the planet into Earth.C．Sending people to the planet from Earth.D．Making the planet’s environment similar to Earth’s.14．Why did scientists conduct a test in Hawaii?A．To learn about the local customs.B．To find ways to terraform Mars.C．To confirm one of their concerns.D．To prove Stephen Hawking’s belief wrong.15．What conclusion can we draw about human living on Mars according to the author?A．Humans’ living on Mars is impossible.B．Humans’ living on Mars is probably practical.C．Humans’ living on Mars will become a reality in 2030．D．Humans’ living on Mars has met with many experts’ challenges.How to Improve Your Study HabitsPerhaps you are an average student with average intelligence. You do well enough in school.16 This is not necessanly the case, however. You can receive better grades if you want to. Yes, even students of average intelligence can be top students without additional work. Here are some tips for you:1．Plan your time carefully. Make a list of your weekly tasks. Then make a schedule or chart of your time. Fill in committed time such as eating, sleeping, meetings, classes, etc. Then decide on good, regular times for studying. 17 As the saying goes: “All work and no play makes Jack a dull boy.” So it’s important to set aside time for relaxation, hobbies, and entertainment as well. Furthermore, it will enable you to plan your activities so that you have adequate time for both work and play.2．Find a good place to study. Choose one place for your study area. It may be a desk or a chair at home or in the school library, but it should be comfortable, and it should not have distractions. When you begin to work, you should be able to concentrate on the subject.3．18 Listening to what the teacher says in class means less work later. Sit where you can see and hear well. Take notes to help you remember what the teacher says.4．Study regularly. Go over your notes as soon as you can after class. Review important points mentioned in class as well as points you remain confused about. If you review your notes and textbook regularly, the material will become more meaningful and you will remember it longer. 195．Develop a good attitude about tests. The purpose of a test is to show what you have learned about a subject. The world won’t end if you don’t pass a test, so don’t worry excessively about a single test. 20 They also let you know what you need to spend more time studying on.A．Raise questions actively.B．Tests provide more than grades.C．Make good use of your time in class.D．But you probably think you will never be a top student.E．Certainly, we shouldn’t let studying occupy all the schedule.F．Those who organize their time carefully can study efficiently.G．Besides, regular review contributes to improved performances on test.二、完形填空During World War II, Duchess Nina Douglas played a vital role in looking after animals.As the war broke out, some departments 21 orders for the mass killing livestock (家畜) to prevent them from being captured by the enemy. Duchess Nina 22 a campaign to save animals and soon became known as the “animal heroine” for her 23 .Duchess Nina worked with farmers and animal owners to relocate animals to 24 areas, such as the Scottish Highlands. She also established a network of 25 who helped to care for animals during the war. She 26 feeding programs, medical care and transportation to make animals safe even during the 27 times. The challenging aspect of her work was the 28 of food, so she established a vegetable garden to 29 nutritious meals for animals. She also 30 to the public for donations of food, and was able to 31 enough resources to keep animals fed.Besides saving domestic animals, she was also a strong 32 for wildlife conservation. She started a center for wild animals, working with local protection groups to protect 33 habitats.Some people saw her efforts as a distraction from the war effort. However, she continued to work 34 for animals. After the war. Duchess Nina’s work was recognized by the government and she got an important 35 for her services to animals.21．A．broke B．obeyed C．issued D．tackled 22．A．joined B．addressed C．sponsored D．launched 23．A．talents B．capacities C．efforts D．assessments 24．A．safe B．rare C．industrial D．urban 25．A．gardeners B．volunteers C．servants D．environmentalists 26．A．encountered B．pursued C．obtained D．organized 27．A．busiest B．proudest C．toughest D．freest 28．A．distribution B．shortage C．consumption D．delivery 29．A．create B．share C．donate D．sustain 30．A．handed out B．tried out C．turned out D．reached out31．A．secure B．pool C．waste D．save 32．A．opponent B．advocate C．addict D．victim 33．A．moral B．formal C．final D．natural 34．A．meaninglessly B．harmlessly C．tirelessly D．aimlessly 35．A．scholarship B．opportunity C．qualification D．award三、语法填空阅读下面短文，在空白处填入1个适当的单词或括号内单词的正确形式。

分子生物学名词解释合集abundance (mRNA丰度)：指每个细胞中mRNA分子的数目。

abundant mRNA(高丰度mRNA)：由少量不同种类mRNA组成，每一种在细胞中出现大量拷贝。

acceptor splicing site (受体剪切位点)：内含子右末端和相邻外显子左末端的边界。

acentric fragment(无着丝粒片段)：(由打断产生的)染色体无着丝粒片段缺少中心粒，从而在细胞分化中被丢失。

active site(活性位点)：蛋白质上一个底物结合的有限区域。

allele(等位基因)：在染色体上占据给定位点基因的不同形式。

allelic exclusion(等位基因排斥)：形容在特殊淋巴细胞中只有一个等位基因来表达编码的免疫球蛋白质。

allosteric control(别构调控)：指蛋白质一个位点上的反应能够影响另一个位点活性的能力。

Alu-equivalent family(Alu 相当序列基因)：哺乳动物基因组上一组序列，它们与人类Alu家族相关。

Alu family (Alu家族)：人类基因组中一系列分散的相关序列，每个约300 bp长。

每个成员其两端有Alu 切割位点(名字的由来)。

α-amanitin(鹅膏覃碱)：是来自毒蘑菇amanita phalloides 二环八肽，能抑制真核RNA聚合酶，特别是聚合酶II 转录。

amber codon (琥珀密码子)：核苷酸三联体uag，引起蛋白质合成终止的三个密码子之一。

amber mutation (琥珀突变)：指代表蛋白质中氨基酸密码子占据的位点上突变成琥珀密码子的任何DNA改变。

amber suppressors (琥珀抑制子)：编码trna的基因突变使其反密码子被改变，从而能识别uag 密码子和之前的密码子。

aminoacyl-tRNA(氨酰-tRNA)：是携带氨基酸的转运RNA，共价连接位在氨基酸的NH2基团和tRNA终止碱基的3￠或者2￠-oh 基团上。