下载文档原格式
南方医科大学细胞生物学习题备注：有的章节判定题假设只标注T那么其他题目均为F,同理，只标第理细胞生题学翳学一、单项选择题2.DNA双螺旋模型是美国人J.D.Watson和英国人F.H.C.Crick哪一年提出的（C）3.那两位科学家最先提出了细胞学说（A）A.Shleiden、Schwann、Porkinjie、FlemmingD.Hertwig、Hooke、Click4.最先观看到活细胞的学者是（D）A.BrownRB.FlemmingWC.HookeRD.LeeuwenhoekAE.DarvinC5.最先观看到有丝割裂的学者是（B）A.BrownRB.FlemmingWC.HookeRD.LeeuwenhoekAE.DarvinC二、多项选择题1.以下哪些是今世细胞生物学研究的热点（BCDE）A.细胞器结构B.细胞凋亡C.细胞周期调控D.细胞通信E.肿瘤细胞2.现代的细胞生物学在哪些层次上研究细胞的生命活动（ABE）A.分子水平B.亚细胞水平C.组织水平D.器官水平E.细胞整体水平三、是非题1.细胞最先于1665年由RobertHooke发觉。
（A）2.在十八世纪Hooke和Flemming提出了细胞学说。
（B）3.细胞生物学确实是细胞学。
（B）4.医学细胞生物学研究任务之一确实是探讨疾病的发病机制。
（A）5.医学细胞生物学实质确实是细胞生物学在医学中的应用。
（A）第二章细胞的起源与进化一、单项选择题1.以下有关原核细胞和真核细胞的表达，哪项有误（A）A.原核细胞有细胞壁，真核细胞没有B.原核细胞无完整细胞核，真核细胞有C.原核细胞和真核细胞均有核糖体D.原核细胞无细胞骨架，真核细胞有E.原核细胞无内膜系统，真核细胞有2.以下有关原核细胞的描述那项有误（C）A.原核细胞无内膜系统B.原核细胞无细胞骨架C.原核细胞无核糖体D.原核细胞无细胞核E.原核细胞有单条染色体3．以下细胞中最小的是（D）A.酵母B.肝细胞C.眼虫D.衣原体E.大肠杆菌4.真核细胞核糖体的沉降系数及其大小亚基的沉降系数别离是（A）A.80S，60S，40SB.70S，50S，30SC.80S，50S，30SD.70S，40S，30SE.80S，60S，30S二、多项选择题1.动物细胞与植物细胞的区别(ABCD)A.动物细胞无细胞壁B.动物细胞无液泡C.动物细胞无叶绿体D.动物细胞有中心粒E.动物细胞比植物细胞大2．以下关于真核细胞的描述正确的选项是(ABDE)A.有真正的细胞核B.有多条由DNA和组蛋白组成的染色体C.基因表达的转录和翻译进程同时进行D.细胞体积较大E.膜性细胞器发达3．原核细胞的特点是(ABCDE)A.没有核膜B.DNA为袒露的环状分子，通常没有结合蛋白。
100句。
想学好英语的，一定不要错过。
1. Typical of the grassland dwellers of the continent is the American antelope, or pronghorn.1.美洲羚羊，或称叉角羚，是该大陆典型的草原动物。
2. Of the millions who saw Haley’s comet in 1986, how many people will 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当中，有多少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，悲伤和惊奇都会行之于色，这在全人类是共通的。
4. Because of its irritating effect on humans, the use of phenol as a general antiseptic has been largely discontinued.4.由于苯酚对人体带有刺激性作用，它基本上已不再被当作常用的防腐剂了。
5. In group to remain in existence, a profit-making organization must, in the long run, produce something consumers consider useful or desirable.5.任何盈利组织若要生存，最终都必须生产出消费者可用或需要的产品。
a r X i v :a s t r o -p h /0504501v 1 22 A p r 2005From Little Bangs to the Big BangJohn EllisTheory Division,Physics Department,CERN,CH-1211Geneva 23,Switzerland E-mail:john.ellis@cern.ch CERN-PH-TH/2005-070astro-ph/0504501Abstract.The ‘Little Bangs’made in particle collider experiments reproduce the conditions in the Big Bang when the age of the Universe was a fraction of a second.It is thought that matter was generated,the structures in the Universe were formed and cold dark matter froze out during this very early epoch when the equation of state of the Universe was dominated by the quark-gluon plasma (QGP).Future Little Bangs may reveal the mechanism of matter generation and the nature of cold dark matter.Knowledge of the QGP will be an essential ingredient in quantitative understanding of the very early Universe..1.The Universe is Expanding The expansion of the Universe was first established by Hubble’s discovery that distant galaxies are receding from us,with redshifts proportional to their relative distances from us.Extrapolating the present expansion backwards,there is good evidence that the Universe was once 3000times smaller and hotter than today,provided by the cosmic microwave background (CMB)radiation.This has a thermal distribution and is very isotropic,and is thought to have been released when electrons combined with ions from the primordial electromagnetic plasma to form atoms.The observed small dipole anisotropy is due to the Earth’s motion relative to this cosmic microwave background,and the very small anisotropies found by the COBE satellite are thought to have led to the formation of structures in the Universe,as discussed later [1].Extrapolating further back in time,there is good evidence that the Universe was once a billion times smaller and hotter than today,provided by the abundances of light elements cooked in the Big Bang [2].The Universe contains about 24%by mass of 4He,and somewhat less Deuterium,3He and 7Li.These could only have been cooked by nuclear reactions in the very early Universe,when it was a billion times smaller and hotter than today.The detailed light-element abundances depend on the amount of matter in the Universe,and comparison between observations and calculations suggests that there is not enough matter to stop the present expansion,or even to explain the amount of matter in the galaxies and their clusters.The calculations of the light-element abundances also depend on the number of particle types,and in particular on the number of different neutrino types.This is now known from particle collider experiments to be three [3],with a corresponding number of charged leptons and quark pairs.2.The Very Early Universe and the Quark-Gluon PlasmaWhen the Universe was very young:t →0,also the scale factor a characterizing its size would have been very small:a →0,and the temperature T would have been very large,withcharacteristic relativistic particle energies E ∼T .In normal adiabatic expansion,T ∼1/a ,and,while the energy density of the Universe was dominated by relativistic matter,t ∼1/T 2.The following are some rough orders of magnitude:when the Universe had an age t ∼1second,the temperature was T ∼10,000,000,000degrees,and characteristic thermal energies were E ∼1MeV,comparable with the mass of theelectron.It is clear that one needs particle physics to describe the earlier history of the Universe [1].The very early Universe was presumably filled with primordial quark-gluon plasma (QGP).When the Universe was a few microseconds old,it is thought to have exited from this QGP phase,with the available quarks and gluons combining to make mesons and baryons.The primordial QGP would have had a very low baryon chemical potential µ.Experiments with RHIC reproduce cosmological conditions more closely than did previous SPS experiments,as seen in Fig.1,and the LHC will provide [4]an even closer approximation to the primordial QGP.I shall not discuss here the prospects for discovering quark matter inside dense astrophysical objects such as neutron stars,which would have a much larger baryon chemical potential.TµTc ~ 170 MeV µ ∼ o 922 MeV Figure 1.The phase diagram of hot and dense QCD for different values of the baryon chemical potential µand temperature T [5],illustrating the physics reaches of SPS,RHIC and the ALICE experiment at the LHC [4].To what extent can information about the early Universe cast light on the quark-hadron phase transition?The latest lattice simulations of QCD with two light flavours u,d and one moderately heavy flavour s suggest that there was no strong first-order transition.Instead,there was probably a cross-over between the quark and hadron phases,see,for example,Fig.2[5],during which the smooth expansion of the Universe is unlikely to have been modified substantially.Specifically,it is not thought that this transition would have induced inhomogeneities large enough to have detectable consequences today.3.Open Cosmological QuestionsThe Standard Model of cosmology leaves many important questions unanswered.Why is the Universe so big and old?Measurements by the WMAP satellite,in particular,indicate that its age is about 14,000,000,000years [6].Why is its geometry nearly Euclidean?Recent data indicate that it is almost flat,close to the borderline for eternal expansion.Where did the matter come from?The cosmological nucleosynthesis scenario indicates that there is approximately one proton in the Universe today for every 1,000,000,000photons,and no detectable amount0.81 1.2 1.4 1.6 1.82T/T 000.20.40.60.8µq /T =0.8µq /T =1.0µq /T =0.6µq /T =0.4µq /T =0.2∆(p/T 4)Figure 2.The growth of the QCD pressure with temperature,for different values of the baryon chemical potential µ[5].The rise is quite smooth,indication that there is not a strong first-order phase transition,and probably no dramatic consequences in the early Universe.of antimatter.How did cosmological structures form?If they did indeed form from the ripples observed in the CMB,how did these originate?What is the nature of the invisible dark matter thought to fill the Universe?Its presence is thought to have been essential for the amplification of the primordial perturbations in the CMB.It is clear that one needs particle physics to answer these questions,and that their solutions would have operated in a Universe filled with QGP.4.A Strange Recipe for a UniverseAccording to the ‘Concordance Model’suggested by a multitude of astrophysical and cosmological observations,the total density of the Universe is very close to the critical value:ΩT ot =1.02±0.02,as illustrated in Fig.3[6].The theory of cosmological inflation suggests that the density should be indistinguishable from the critical value,and this is supported by measurements of the CMB.On the other hand,the baryon density is small,as inferred not only from Big-Bang nucleosynthesis but also and independently from the CMB:ΩBaryons ∼few%.The CMB information on these two quantities comes from observations of peaks in the fluctuation spectrum in specific partial waves corresponding to certain angular scales:the position of the first peak is sensitive to ΩT ot ,and the relative heights of subsequent peaks are sensitive to ΩBaryons .The fraction Ωm of the critical density provided by all forms of matter is not very well constrained by the CMB data alone,but is quite tightly constrained by combining them with observations of high-redshift supernovae [7]and/or large-scale structures [8],each of which favours ΩMatter ∼0.3,as also seen in Fig.3.As seen in Fig.4,there is good agreement between BBN calculations and astrophysical observations for the Deuterium and 4He abundances [2].The agreement for 7Li is less striking,though not disastrously bad 1.The good agreement between the corresponding 1It seems unlikely that the low abundance of 7Li observed could have been modified significantly by the decaysFigure3.The density of matterΩm and dark energyΩΛinferred from WMAP and other CMB data(WMAPext),and from combining them with supernova and Hubble Space Telescope data[6].determinations ofΩBaryons obtained from CMB and Big-Bang nucleosynthesis calculations in conventional homogeneous cosmology imposes important constraints on inhomogeneous models of nucleosynthesis.In particular,they exclude the possibility thatΩBaryons might constitute a large fraction ofΩT ot.Significant inhomogeneities might have been generated at the quark-hadron phase transition,if it was stronglyfirst-order[10].Although,as already discussed,lattice calculations suggest that this is rather unlikely,heavy-ion collision experiments must be thefinal arbiter on the nature of the quark-hadron phase transition.5.Generating the Matter in the UniverseAs was pointed out by Sakharov[11],there are three essential requirements for generating the matter in the Universe via microphysics.First,one needs a difference between matter and antimatter interactions,as has been observed in the laboratory in the forms of violations of C and CP in the weak interactions.Secondly,one needs interactions that violate the baryon and lepton numbers,which are present as non-perturbative electroweak interactions and in grand unified theories,but have not yet been seen.Finally,one needs a breakdown of thermal equilibrium, which is possible during a cosmological phase transition,for example at the GUT or electroweak scale,or in the decays of heavy particles,such as a heavy singlet neutrinoνR[12].The issueof heavy particles[9]:it would be valuable to refine the astrophysical determinations.Figure4.Primordial light element abundances as predicted by BBN(light)and WMAP(dark shaded regions)[2],for(a)D/H,(b)the4He abundance Y p and(c)7Li/H[2].then is whether we will be able to calculate the resulting matter density in terms of laboratory measurements.Unfortunately,the Standard Model C and CP violation measured in the quark sector seem unsuitable for baryogenesis,and the electroweak phase transition in the Standard Model would have been second order.However,additional CP violation and afirst-order phase transition in an extended electroweak Higgs sector might have been able to generate the matter density[13],and could be testable at the LHC and/or ILC.An alternative is CP violation in the lepton sector,which could be probed in neutrino oscillation experiments,albeit indirectly, or possibly in the charged-lepton sector,which might be related more directly to the matter density[14].In any case,detailed knowledge of the QGP equation of state would be necessary if one were ever to hope to be able to calculate the baryon-to-entropy ratio with an accuracy of a few percent.6.The Formation of Structures in the UniverseThe structures seen in the Universe-clusters,galaxies,stars and eventually ourselves-are all thought to have developed from primordialfluctuations in the CMB.This idea is supported visually by observations of galaxies,which look smooth at the largest scales at high redshifts, but cluster at smaller scales at low redshifts[15].This scenario requires amplification of the smallfluctuations observed in the CMB,which is possible with massive non-relativistic weakly-interacting particles.On the other hand,relativistic light neutrinos would have escaped from smaller structures,and so are disfavoured as amplifiers.Non-relativistic‘cold dark matter’is preferred,as seen in a comparison of the available data on structures in the Universe with the cosmological Concordance Model[8].The hot news in the observational tests of this scenario has been the recent detection of baryonic ripples from the Big Bang[16],as seen in Fig.5.These are caused by sound waves spreading out from irregularities in the CMB,which show up in the correlation function between structures in the(near-)contemporary Universe as features with a characteristic size.In addition to supporting the scenario of structure formation by amplification of CMBfluctuations, these observations provide measurements of the expansion history and equation of state of the Universe.Figure5.The baryonic‘ripple’in the large-scale correlation function of luminous red galaxies observed in the Sloan Digital Sky Survey of galactic redshifts[16].7.Do Neutrinos Matter?Oscillation experiments tell us that neutrinos have very small but non-zero masses[17,18], and so must make up at least some of the dark matter.As already mentioned,since such light neutrinos move relativistically during the epoch of structure formation,they would have escaped from galaxies and not contributed to their formation,whereas they could have contributed to the formation of clusters.Conversely,the success of the cosmological Concordance Model enables one to set a cosmological upper limit on the sum of light neutrino masses,as seen in Fig.6:Σνmν<0.7eV[6],which is considerably more sensitive than direct laboratory searches.In the future,this cosmological sensitivity might attain the range indicated by atmospheric neutrino data[17].However,even if no dark matter effect of non-zero light neutrino masses is observed,this does not mean that neutrinos have no cosmological role,since unstable heavier neutrinos might have generated matter via the Sakharov mechanism[11].8.Particle Dark Matter CandidatesCandidates for the non-relativistic cold dark matter required to amplify CMBfluctuations include the axion[19],TeV-scale weakly-interacting massive particles(WIMPs)produced thermally in the early Universe,such as the lightest supersymmetric partner of a Standard Model particle(probably the lightest neutralinoχ),the gravitino(which is likely mainly to have been produced in the very early Universe,possibly thermally),and superheavy relic particles that might have been produced non-thermally in the very early Universe[20](such as the‘cryptons’predicted in some string models[21]).9.Supersymmetric Dark MatterSupersymmetry is a very powerful symmetry relating fermionic‘matter’particles to bosonic ‘force’particles[22].Historically,the original motivations for supersymmetry were purely theoretical:its intrinsic beauty,its ability to tame infinities in perturbation theory,etc.The first phenomenological motivation for supersymmetry at some accessible energy was that itFigure6.The likelihood function for the total neutrino densityΩνh2derived by WMAP[6]. The upper limit mν<0.23eV applies if there are three degenerate neutrinos.might also help explain the electroweak mass scale,by stabilizing the hierarchy of mass scales in physics[23].It was later realized also that the lightest supersymmetric particle(LSP)would be stable in many models[24].Moreover,it should weigh below about1000GeV,in order to stabilize the mass hierarchy,in which case its relic density would be similar to that required for cold dark matter[25].As described below,considerable effort is now put into direct laboratory searches for supersymmetry,as well as both direct and indirect astrophysical searches.Here I concentrate on the minimal supersymmetric extension of the Standard Model(MSSM), in which the Standard Model particles acquire superpartners and there are two doublets of Higgs fields.The interactions in the MSSM are completely determined by supersymmetry,but one must postulate a number of soft supersymmetry-breaking parameters,in order to accommodate the mass differences between conventional particles and their superpartners.These parameters include scalar masses m0,gaugino masses m1/2,and trilinear soft couplings A0.It is often assumed that these parameters are universal,so that there is a single m0,a single m1/2,and a single A0parameter at the input GUT scale,a scenario called the constrained MSSM(CMSSM). However,there is no deep theoretical justification for this universality assumption,except in minimal supergravity models.These models also make a prediction for the gravitino mass: m3/2=m0,which is not necessarily the case in the general CMSSM.As already mentioned,the lightest supersymmetric particle is stable in many models,this because of the multiplicative conservation of R parity,which is a combination of spin S,lepton number L and baryon number B:R=(−1)2S−L+3B.It is easy to check that conventional particles have R=+1and sparticles have R=−1.As a result,sparticles are always produced in pairs,heavier sparticles decay into lighter ones,and the lightest supersymmetric particle (LSP)is stable.The LSP cannot have strong or electromagnetic interactions,because these would bind it toconventional matter,creating bound states that would be detectable as anomalous heavy nuclei.Among the possible weakly-interacting scandidates for the LSP,one finds the sneutrino ,which has been excluded by a combination of LEP and direct searches for astrophysical dark matter,the lightest neutralino χ,and the gravitino .There are good prospects for detecting the neutralino or gravitino in collider experiments,and neutralino dark matter may also be detectable either directly or indirectly,but gravitino dark matter would be a nightmare for detection.10.Constraints on SupersymmetryImportant constraints on supersymmetry are imposed by the absences of sparticles at LEP and the Tevatron collider,implying that sleptons and charginos should weigh >100GeV [26],and that squarks and gluinos should weigh >250GeV,respectively.Important indirect constraints are imposed by the LEP lower limit on the mass of the lightest Higgs boson,114GeV [27],and the experimental measurement of b →sγdecay [28],which agrees with the Standard Model.The measurement of the anomalous magnetic moment of the muon,g µ−2,also has the potential to constrain supersymmetry,but the significance of this constraint is uncertain,in the absence of agreement between the e +e −annihilation and τdecay data used to estimate the Standard Model contribution to g µ−2[29].Finally,one of the strongest constraints on the supersymmetric parameter space is that imposed by the density of dark matter inferred from astrophysical and cosmological observations.If this is composed of the lightest neutralino χ,one has 0.094<Ωχh 2<0.129[6],and it cannot in any case be higher than this.For generic domains of the supersymmetric parameter space,this range constrains m 0with an accuracy of a few per cent as a function of m 1/2,as seen in Fig.7[30].m 0 (G e V )m 1/2 (GeV)m 0 (G e V )m 1/2 (GeV)Figure 7.The (m 1/2,m 0)planes for (a)tan β=10and tan β=50with µ>0and A 0=0,assumingm t =175GeV and m b (m b )Figure8.The factor h eff(T)calculated using different equations of state[31].11.The Relic Density and the Quark-Gluon PlasmaThe accurate calculation of the relic density depends not only on the supersymmetric model parameters,but also on the effective Hubble expansion rate as the relic particles annihilate and freeze out of thermal equilibrium[25]:˙n+3Hn=−<σann v>(n2−n2eq).This is,in turn,sensitive to the effective number of particle species:Y0≃ 4521g eff 13d ln h effm N L V S P (G e V )m LVSP (GeV)Figure 9.Scatter plot of the masses of the lightest visible supersymmetric particle (LVSP)and the next-to-lightest visible supersymmetric particle (NLVSP)in the CMSSM.The darker (blue)triangles satisfy all the laboratory,astrophysical and cosmological constraints.For comparison,the dark (red)squares and medium-shaded (green)crosses respect the laboratory constraints,but not those imposed by astrophysics and cosmology.In addition,the (green)crosses represent models which are expected to be visible at the LHC.The very light (yellow)points are those for which direct detection of supersymmetric dark matter might be possible [33].13.Strategies for Detecting Supersymmetric Dark MatterThese include searches for the annihilations of relic particles in the galactic halo:χχ→antiprotons or positrons,annihilations in the galactic centre:χχ→γ+...,annihilations in the core of the Sun or the Earth:χχ→ν+···→µ+···,and scattering on nuclei in the laboratory:χA →chiA .After some initial excitement,recent observations of cosmic-ray antiprotons are consistent with production by primary matter cosmic rays.Moreover,the spectra of annihilation positrons calculated in a number of CMSSM benchmark models [32]seem to fall considerably below the cosmic-ray background [37].Some of the spectra of photons from annihilations in Galactic Centre,as calculated in the same set of CMSSM benchmark scenarios,may rise above the expected cosmic-ray background,albeit with considerable uncertainties due to the unknown enhancement of the cold dark matter density.In particular,the GLAST experiment may have the best chance of detecting energetic annihilation photons [37],as seen in the left panel of Fig.10.Annihilations in the Solar System also offer detection prospects in some of the benchmark scenarios,particularly annihilations inside the Sun,which might be detectable in experiments such as AMANDA,NESTOR,ANTARES and particularly IceCUBE,as seen in the right panel of Fig.10[37].The rates for elastic dark matter scattering cross sections calculated in the CMSSM are typically considerably below the present upper limit imposed by the CDMS II experiment,in both the benchmark scenarios and the global fit to CMSSM parameters based on present data [38].However,if the next generation of direct searches for elastic scattering can reach a sensitivity of 10−10pb,they should be able to detect supersymmetric dark matter in many supersymmetric scenarios.Fig.11compares the cross sections calculated under a relatively optimistic assumption for the relevant hadronic matrix element σπN =64MeV,for choices of CMSSM parameters favoured at the 68%(90%)confidence level in a recent analysis using theFigure 10.Left panel:Spectra of photons from the annihilations of dark matter particles in the core of our galaxy,in different benchmark supersymmetric models [37].Right panel:Signals for muons produced by energetic neutrinos originating from annihilations of dark matter particles in the core of the Sun,in the same benchmark supersymmetric models [37].10-1210-1110-1010-910-810-710-610-50 200 400 600800 1000σ (p b )m χ (GeV)CMSSM, tan β=10, µ>0Σ=64 MeV CDMS II CL=90%CL=68%10-1210-1110-1010-910-810-710-610-5 0 200 400 600 800 1000σ (p b )m χ (GeV)CMSSM, tan β=50, µ>0Σ=64 MeV CDMS II CL=90%CL=68%Figure 11.Scatter plots of the spin-independent elastic-scattering cross section predicted in the CMSSM for (a)tan β=10,µ>0and (b)tan β=50,µ>0,each with σπN =64MeV [38].The predictions for models allowed at the 68%(90%)confidence levels [39]are shown by blue ×signs (green +signs).observables m W ,sin 2θW ,b →sγand g µ−2[39].14.Connections between the Big Bang and Little BangsAstrophysical and cosmological observations during the past few years have established a Concordance Model of cosmology,whose matter content is quite accurately determined.Most of the present energy density of the Universe is in the form of dark vacuum energy,with about 25%in the form of dark matter,and only a few %in the form of conventional baryonic matter.Two of the most basic questions raised by this Concordance Model are the nature of the dark matter and the origin of matter.Only experiments at particle colliders are likely to be able to answer these and other fundamental questions about the early Universe.In particular,experiments at the LHC will recreate quark-gluon plasma conditions similar to those when the Universe was less than a microsecond old[4],and will offer the best prospects for discovering whether the dark matter is composed of supersymmetric particles[40,41].LHC experiments will also cast new light on the cosmological matter-antimattter asymmetry[42].Moreover,discovery of the Higgs boson will take us closer to the possibilities for inflation and dark energy.There are many connections between the Big Bang and the little bangs we create with particle colliders.These connections enable us both to learn particle physics from the Universe,and to use particle physics to understand the Universe.References[1]J.R.Ellis,Lectures given at16th Canberra International Physics Summer School on The New Cosmology,Canberra,Australia,3-14Feb2003,arXiv:astro-ph/0305038;K.A.Olive,TASI lectures on Astroparticle Physics,arXiv:astro-ph/0503065.[2]R.H.Cyburt, B. D.Fields,K. A.Olive and E.Skillman,Astropart.Phys.23(2005)313[arXiv:astro-ph/0408033].[3]LEP Electroweak Working Group,http://lepewwg.web.cern.ch/LEPEWWG/Welcome.html.[4]ALICE Collaboration,http://pcaliweb02.cern.ch/NewAlicePortal/en/Collaboration/index.html.[5] C.R.Allton,S.Ejiri,S.J.Hands,O.Kaczmarek,F.Karsch,ermann and C.Schmidt,Nucl.Phys.Proc.Suppl.141(2005)186[arXiv:hep-lat/0504011].[6] D.N.Spergel et al.[WMAP Collaboration],Astrophys.J.Suppl.148(2003)175[arXiv:astro-ph/0302209].[7] A.G.Riess et al.[Supernova Search Team Collaboration],Astron.J.116(1998)1009[arXiv:astro-ph/9805201];S.Perlmutter et al.[Supernova Cosmology Project Collaboration],Astrophys.J.517(1999)565[arXiv:astro-ph/9812133].[8]N. A.Bahcall,J.P.Ostriker,S.Perlmutter and P.J.Steinhardt,Science284(1999)1481[arXiv:astro-ph/9906463].[9]J.R.Ellis,K.A.Olive and E.Vangioni,arXiv:astro-ph/0503023.[10]K.Jedamzik and J.B.Rehm,Phys.Rev.D64(2001)023510[arXiv:astro-ph/0101292].[11] A.D.Sakharov,Pisma Zh.Eksp.Teor.Fiz.5(1967)32[JETP Lett.5(1967SOPUA,34,392-393.1991UFNAA,161,61-64.1991)24].[12]M.Fukugita and T.Yanagida,Phys.Lett.B174(1986)45.[13]See,for example:M.Carena,M.Quiros,M.Seco and C.E.M.Wagner,Nucl.Phys.B650(2003)24[arXiv:hep-ph/0208043].[14]See,for example:J.R.Ellis and M.Raidal,Nucl.Phys.B643(2002)229[arXiv:hep-ph/0206174].[15]The2dF Galaxy Redshift Survey,.au/2dFGRS/.[16] D.J.Eisenstein et al.,arXiv:astro-ph/0501171;S.Cole et al.[The2dFGRS Collaboration],arXiv:astro-ph/0501174.[17]Y.Fukuda et al.[Super-Kamiokande Collaboration],Phys.Rev.Lett.81(1998)1562[arXiv:hep-ex/9807003].[18]See,for example:Q.R.Ahmad et al.[SNO Collaboration],Phys.Rev.Lett.87(2001)071301[arXiv:nucl-ex/0106015].[19]See,for example:S.Andriamonje et al.[CAST Collaboration],Phys.Rev.Lett.94(2005)121301[arXiv:hep-ex/0411033].[20] D.J.H.Chung,E.W.Kolb and A.Riotto,Phys.Rev.D59(1999)023501[arXiv:hep-ph/9802238].[21]K.Benakli,J.R.Ellis and D.V.Nanopoulos,Phys.Rev.D59(1999)047301[arXiv:hep-ph/9803333].[22]J.Wess and B.Zumino,Nucl.Phys.B70(1974)39.[23]L.Maiani,Proceedings of the1979Gif-sur-Yvette Summer School On Particle Physics,1;G.’t Hooft,inRecent Developments in Gauge Theories,Proceedings of the Nato Advanced Study Institute,Cargese,1979, eds.G.’t Hooft et al.,(Plenum Press,NY,1980);E.Witten,Phys.Lett.B105(1981)267.[24]P.Fayet,Unification of the Fundamental Particle Interactions,eds.S.Ferrara,J.Ellis andP.van Nieuwenhuizen(Plenum,New York,1980),p.587.[25]J.Ellis,J.S.Hagelin,D.V.Nanopoulos,K.A.Olive and M.Srednicki,Nucl.Phys.B238(1984)453;see alsoH.Goldberg,Phys.Rev.Lett.50(1983)1419.[26]The Joint LEP2Supersymmetry Working Group,http://lepsusy.web.cern.ch/lepsusy/.[27]LEP Higgs Working Group for Higgs boson searches,OPAL Collaboration,ALEPH Collaboration,DELPHICollaboration and L3Collaboration,Phys.Lett.B565(2003)61[arXiv:hep-ex/0306033].Search for neutral Higgs bosons at LEP,paper submitted to ICHEP04,Beijing,LHWG-NOTE-2004-01,ALEPH-2004-008,DELPHI-2004-042,L3-NOTE-2820,OPAL-TN-744,http://lephiggs.web.cern.ch/LEPHIGGS/papers/August2004。
病理学试卷及答案一、名词解释（本大题共10小题，每题2分，共20分）1、机化2、梗死3、炎性息肉4、肿瘤的异质性5、小叶性肺炎6、carcinoma in situ7、tuberculoma8、abscess9、thrombosis10、fibroma二、简答题（本大题共2小题，每题5分，共10分）1、简述肿瘤生长的动力学特点。
2、简述血栓栓子的运行途径。
三、问答题（本大题共2小题，共25分）1试述主动脉粥样硬化的病变特点和对机体的影响。
(10分)2试以胃溃疡和胃癌为例，（1）说明良性的病变与恶性肿瘤的鉴别要点；（2）疾病发生发展过程中对机体会产生的哪些影响？（15分）四、汉译英（本大题共1小题，共5分）Inflammation is the physiological response to tissue injury.It is characterized that the generation of inflammatory mediators and movement of fluid and leukocytes from the blood into extravascular tissues.Inflammation is usually classified according to its time course as:acute inflammation and chronic inflammation.五、选择题（本大题共40小题，每题1分，共40分）1、长期营养不良时,首先发生萎缩的组织或器官是A.骨骼肌B.脂肪组织C.肝D.脑E.心肌2、微循环内纤维素性血栓又叫:A.透明全栓B.白色血栓C.红色血栓D.混合血栓E.层状血栓3、引起炎症的因素中最常见的是?A.机械性损伤B.物理性损伤C.化学性损伤D.生物性损伤E.遗传性缺陷4、高血压脑内出血预后最差的部位是A.基底核外侧型B.基底核内侧型C.脑桥出血D.小脑出血E.蛛网膜下腔出血5、鼻咽癌常发生在A.鼻咽后部B.鼻咽顶部C.鼻咽侧壁D.鼻咽前壁E.鼻咽底部6、肺癌最常见的类型是：A.鳞状细胞癌B.高分化腺癌D.疤痕癌E.未分化癌7、肝癌不转移到A淋巴结B.脾脏C.卵巢D.肺E.脑8、关于食管的早期癌，哪项的叙述不正确？A.5年存活率可达90％B.包括原位癌C.包括未侵入固有膜的癌D.包括未侵入粘膜下层的癌E.包括未侵入深肌层的癌9、在我国，慢性萎缩性胃炎好发于：A.胃窦部B.胃大弯C.胃小弯D.贲门E胃底部10、下述哪项不是膀胱移行细胞癌的分级参数指标?A.肿瘤有或无蒂B.有无乳头状结构C.瘤细胞层数D.异型性大小E.是否易复发11、弥漫性硬化性肾小球肾炎最常见的死亡原因是A.心衰C.继发感染D.电解质紊乱E.肾功能衰竭12、淋病是一种()炎症A.急性化脓性B.慢性化脓性C.出血性D.变质性E.浆液卡他性13、结核病的基本病变属于A.急性增生性炎B.纤维素性炎C.化脓性炎D.变质性炎E.以上均不是14、中毒型细菌性痢疾常由下列哪项痢疾杆菌引起A.宋内氏菌或鲍氏菌B.鲍氏菌或志贺氏菌C.志贺氏菌或福氏菌D.福氏菌或宋内氏菌E.志贺氏菌或宋内氏菌15、引起血吸虫病感染的是A.虫卵B.毛蚴C.母胞蚴D.子胞蚴E.尾蚴16、肠阿米巴病最常引起的并发症为:B.脑脓肿C.肝脓肿D.心包炎E.脓胸17、肠阿米巴病最常发生在A.空肠B.回肠C.盲肠和升结肠D.横结肠E.乙状结肠和直肠18、细胞水肿最重要的超微结构特征A.内质网扩张断裂成小泡B.细胞膜内折,水分积聚C.自噬泡增多D.线粒体肿大,嵴变短变少甚至消失E.粗面内质网脱颗粒19、除下列哪一项外,均为一期愈合?A.组织缺损少B.无感染C.适量的肉芽组织D.表皮再生E.过量的疤痕组织20、下述关于肺淤血的记述中,哪一项是错误的?A.肺泡壁毛细血管扩张B.肺泡内中性白细胞和纤维素渗出C.肺泡腔内有水肿液D.可发生漏出性出血E.常可见心力衰竭细胞21、炎症局部的基本病变是A.变质,渗出,增生B.变性,坏死,增生C.血管变化及渗出物形成D.局部物质代谢紊乱E.炎症介质的释放22、肿瘤异型性是指:A.肿瘤外观形态的差异B.肿瘤间质与其起源组织间质分化程度的差异C.肿瘤实质与间质与起源组织分化程度的差异D.肿瘤组织在细胞形态和组织结构上与其起源组织的差异E.肿瘤实质与间质比例的差异23、血管壁玻璃样变常见于：A慢性肾小球肾炎B风湿性心脏病C高血压病D动脉粥样硬化E高血压病及慢性肾小球肾炎24、急性细菌性心内膜炎的瓣膜赘生物中，不具有的成分是：A.大量中性白细胞B.坏死组织C.细菌D.多量肉芽组织E.血小板和纤维索25、动脉瘤是A.一种血管肿瘤B.动脉壁发生的肿瘤C.动脉壁损伤、薄弱、局部扩张、膨出D.动脉内血栓形成E.局部血管痉挛，其周围小血管呈瘤样扩张26、风湿性心肌炎早期的主要病理变化是：A.心肌细胞变性坏死B.间质纤维素样坏死C.Aschoff小体形成D.纤维化及疤痕形成E.中性白细胞灶状浸润27、下列关于风湿性心内膜炎的描述中哪项是正确的？A.瓣膜赘生物牢固相连B.瓣膜赘生物内有细菌C.受累瓣膜易穿孔D.受累瓣膜以三尖瓣为主E.赘生物位于房室瓣的心室面28、大叶性肺炎患者咳铁锈色痰是由于：A.肺肉质变B.肺泡内渗出物的崩解C.肺泡壁的坏死D.肺内小的化脓及出血E.肺泡壁的坏死及渗出物的崩解29、胃癌最多见的肉眼类型是A.弥漫浸润型B.息肉型C.菜花型D.溃疡型E.缩窄型30、阑尾系膜静脉血栓形成多见于下列哪一种阑尾炎？A.急性蜂窝织炎性阑尾炎B.急性单纯性阑尾炎C.急性坏疽性阑尾炎D.慢性阑尾炎E.慢性阑尾炎急性发作31、关于慢性十二指肠溃疡的病变及结局，哪项是错的？A.溃疡直径多在1CM以内B.溃疡部位多在十二指肠球部C.数目通常为单个D.容易复发E.少数可癌变32、门脉性肝硬变病变中哪一项是错误的？A.肝体积缩小，重量减轻B.肝硬度增加呈结节状C.显微镜下见假小叶形成D.肝细胞脂肪变性和坏死E.小胆管慢性炎，增生淤胆33、一位妊娠16周的25岁妇女,子宫有20周龄妊娠大小,突然阴道排出一串葡萄样肿物,她可能患有:A.异位妊娠B.妊娠流产C.水泡状胎块D.绒毛膜癌E.子宫平滑肌瘤34、伤寒病变突出表现在:A.肠系膜淋巴结B.肝C.脾D.胆囊E.回肠下段淋巴组织35、除了哪一项外，下列都是癌前疾病？A.慢性胃溃疡B.慢性萎缩性胃炎C.结肠多发性息肉D.阿米巴性结肠炎E.血吸虫性结肠炎36、下列哪项不是胃溃疡的并发症?A.穿孔B.出血C.恶性贫血D.癌变E.幽门狭窄37、按预后的好坏，何杰金病四型的排列顺序应为A.混合细胞型¾淋巴细胞消减型¾结节硬化型¾淋巴细胞为主型B.淋巴细胞消减型¾混合细胞型¾结节硬化型¾淋巴细胞为主型C.淋巴细胞为主型¾结节硬化型¾淋巴细胞消减型¾混合细胞型D.淋巴细胞为主型¾结节硬化型¾混合细胞型¾淋巴细胞消减型E.淋巴细胞消减型¾淋巴细胞为主型¾结节硬化型¾混合细胞型38、快速进行性肾小球能炎的主要病变特点是A.毛细血管壁纤维素样坏死B.脏层上皮细胞大量增生C.伴明显肾小管坏死D.壁层上皮细胞大量增生E.血管内皮细胞增生39、乳腺癌中最常见的类型是A.导管内癌B.浸润性导管癌C.小叶原位癌D.浸润性小叶癌E.典型髓样癌40、下列哪种表现与甲亢无关?A.体温升高B.存在刺激甲状腺的免疫球蛋白LATSC.食欲增加,体重减轻D.心律失常E.低血压,低血钙,低张力答案一、名词解释（本大题共10小题，每题2分，共20分）1 机化：由肉芽组织取代（1分）坏死及异常组织的过程（1分）。
退耦不是缓慢发⽣的-是区分光⼦是否退耦的界限。
已知碰撞速率与尺度因⼦的关系，只要能找到H 与a 的关系，就可以算出所对应的尺度因⼦的值。
-当前宇宙中物质的质量密度远⼤于辐射的，但由尺度因⼦的演化⽅式知， ，早期宇宙中辐射的质量密度曾经占主导。
-不难想象在宇宙演化的某⼀时刻，物质和辐射的质量密度相等，这⼀时刻所对应的尺度因⼦为，这⾥取了h=0.7. -当时，宇宙的演化由辐射主导，相应的Friedmann ⽅程为：，或，因此辐射主导期的哈勃参数为由，可推出 ， -当时 这说明此时光⼦与电⼦和质⼦均是耦合在⼀起的。
-同理也可算出当时光⼦仍未退耦。
-如果宇宙在其膨胀过程中始终保持完全电离的状态，则可以计算出退耦所对应的尺度因⼦和温度分别为（需要考虑辐射主导向物质主导的转变）. -这⼀估计忽略了⼀个重要的因素，即当温度⾜够低使得电⼦和质⼦可以形成中性的氢原⼦⽽能够将氢原⼦电离的⾼能光⼦已经不多时，由于⾃由电⼦的减少，光⼦将迅速退耦。
所以退耦是在中性原⼦的形成，之后迅速完成的。
重组（recombination ）-我们将温度低到⼤量⾃由电⼦可以与质⼦结合形成稳定的氢原⼦的过程称为重组。
由于⾃由电⼦数的减少，使得也迅速减少从⽽⼩于H ，从⽽达到光⼦退耦的条件。
-可以粗略的估计重组发⽣在CMB 的平均光⼦能量刚好等于氢原⼦的电离能时：，得到 Γ=H Γ=5.187×10−21/s a 3Γ=H ρmat =ρmat ,0a −3ρrad =ρrad ,0a −4a rm =ρrad ,0ρmat ,0=Ωrad ,0Ωmat ,0=4.15×10−5h −20.3≈2.8×10−4a <a rm H 2=8πG 3ρrad H 2H 20=8πG 3H 20ρrad ,0a 4=Ωrad ,0a4H =H 0Ωrad ,0a 2=100h ⋅km ⋅s −1⋅Mpc −1 4.15×10−5h −2a 21Mpc =3×1022m H =2.14×10−20s −1a 2a =10−6H =2.14×10−8s −1≪Γ=5.187×10−3/s a =10−5H =2.14×10−10s −1≪Γ=5.187×10−6/s a ≈0.0254,T ≈100K Γ=n e σe c E mean ≃2.7k B T =13.6eV T rec ≃13.6eV 2.7×8.619×10−5eV /K≈5.84×104K-但这⼀估计忽略了⿊体谱中在平均能量之上还有分布着⼤量⾼能光⼦。
医学细胞生物学第一篇细胞生物学概论第一章绪论一．单项选择题1．利用现代技术和手段从分子、亚细胞和整体水平等不同层次上研究细胞生命活动与其根本规律的科学称( )A．细胞遗传学B．细胞生物学C．细胞病理学D．细胞生理学E．细胞形态学2．细胞学说的创始人是( )A．R·HookB．Schleiden and SchwannC．R·BrownD．W·FlemmingE．C．Darwin3．最早发现细胞并将其命名为“cell〞的学者是( )A．R·HookB．A．LeeuwenhookC．R·BrownD．W·FlemmingE．C．Darwin4．最早观察到活细胞的学者是( ) A．R·HookB．A．LeeuwenhookC．R·BrownD．W·FlemmingE．C·Darwin 5．最早自制显微镜并用于观察细胞的学者是( )A．Schleidenand SchwannB．R·HookandA·LeeuwenhookC．VirchowD．R·BrownE．C．Darwin6．最早发现细胞的遗传物质DNA分子为双螺旋结构的学者是( )A．Schleiden and SchwannB．R·Hookand A·LeeuwenhookC．Watson and CrickD．R·BrownE．C·Darwin二．多项选择题1．现代的细胞生物学在哪些层次上来研究细胞的生命活动( )A．分子水平B．亚细胞水平C．细胞整体水平D．组织水平E．器官水平2．活细胞的根本生命活动有( ) A．生长发育B．分裂增殖C．遗传变异D．衰老E．死亡3．19世纪自然科学的三大发现包括( )A．进化论B．细胞学说C．能量守恒定律D．重演率E．别离律三．填空题1．细胞生物学是从____________、____________和____________等3个水平上研究细胞生命活动的科学。
世界卫生组织关于脑膜炎球菌疫苗的立场文件（2011年11月）依据为各成员国提供卫生政策方面指导意见这一职责，世界卫生组织（WHO）就预防具有全球公共卫生影响的疾病的疫苗及联合疫苗问题，发布一系列定期更新的立场文件。
这些文件着重关注疫苗在大规模免疫规划中的使用，归纳了各相关疾病与疫苗的基本背景信息，并就如何在全世界范围内使用这些疫苗表明了世卫组织目前的立场。
这些文件经外部专家和世卫组织工作人员审阅，并由世卫组织的免疫战略咨询专家组（SAGE）（http://www.who.int/immunization/sage/en/）审核和认可。
这些立场文件主要供各国的公共卫生官员和免疫规划管理人员使用。
对这些立场文件感兴趣的还可能包括一些国际资助机构、疫苗制造厂家、医学界、科学媒体和公众。
本文件反映了脑膜炎球菌疫苗领域的最新进展,为各国在国家免疫接种计划中引进和使用脑膜炎球菌疫苗提供了指导意见。
本文件用于取代2002年10月《疫情周报》公布的关于脑膜炎球菌疫苗的立场文件。
SAGE在2011年4月召开会议，讨论了关于脑膜炎球菌疫苗使用的建议。
该会议提出的证据可参见：http://www.who.int/immunization/sage/previous/en/index.html。
本文件的脚注仅提供了部分核心参考文献。
参考文献清单可从以下网址获取：http://www.who.int/immunization/documents/positionpapers/en/index.html。
通过上述链接及本文的参考文献也可获取分级表，利用这些分级表可以评估支持重要建议的科学证据的质量。
引言流行病学在大多数国家，脑膜炎奈瑟菌（Neisseria meningitidis，脑膜炎双球菌）都已被确认为导致脑膜炎和爆发性败血症的首要原因，并且已构成严重的公共卫生问题。
然而，许多国家（尤其是亚洲国家）的监测数据不完整或缺乏，当前尚无关于本病的全球负担估计。
第一章测试1.The time between fertilization and birth is called ___________.A:perinatal periodB:fetal periodC:germinal periodD:prenatal period答案:D2.What’s the function of mucus?A:To attack the sperm from all directionsB:To block the entrance of the sperm to the woman’s womb for all timeC:Transformed by hormones to from a barrier into a chemical rope ladder for sperm to enter the cervixD:To enable the sperm to burrow into the corona radiata答案:C3.Where does the union of a human egg and sperm usually occur in?A:cervixB:ovaryC:vaginaD:the ampulla of the fallopian tube答案:D4.The head of the sperm contains______________.A:the nucleus and the flagellumB:the nucleus and the acrosomeC:the nuclei and the flagellumD:the nuclei and the acrosome答案:B5.The organelles, which are responsible for giving energy to propel the spermtowards the egg are called______?A:torpedoesB:gametesC:flagellumsD:mitochondria答案:D第二章测试1.Head first presentation, which is also called ______ presentation, is the mostcommonly optimal presentation for easy delivery.A:cardinalB:cephalicC:ischialD:breech答案:B2.Which is not the critical factor determines the process that the baby’s headmake through the pelvis into the world?A:Fetal attitudeB:Fetal sizeC:Fetal canalD:Fetal lie答案:C3._________ plots the typical rate of cervical dilation and fetal descent duringactive labour.A:Friedman’s theoryB:Phillips’ curveC:Friedman’s CurveD:Phi llips’ theory答案:C4.In the first stage of labor, the water might break, which is known as______.A:amniotic cavity breakB:amniotic fluid breakC:amniotic ruptureD:amniotic sac rupture答案:D5.In what phase the cervix will dilate from 3cm to 7cm?A:Latent phaseB:Active labor phaseC:Early labor phaseD:Transition phase答案:B第三章测试1.What causes fetal distress?A:bleedingB:lack of oxygen delivered to babyC:high blood pressureD:breech position答案:A2.When the placenta lies low in the uterus and partially or completely coversthe cervix, _____ occursA:placenta previaB:placenta abruptionC:uterine ruptureD:cord prolapse答案:B3.Which of the following is the reason for C-section deliveriesA:family historyB:being overweightC:preeclampsiaD:preference of the mother答案:C4.Originally, Caesarean section is performed to ____A:for religious purposeB:retrieve the infant from a dead or dying motherC:save the mother’s life答案:AB5.Which of the body parts shapes like a tube.A:placentaB:cervixC:wombD:vagina答案:B6.What is the body part involved with pregnancy?A:placentaB:wombC:cervixD:vagina答案:ABCD第四章测试1.What are the benefits of breastfeeding for mothers?A:giving mothers a convenient and inexpensive way to nourish babies B:helping mothers lose excess body weightC:helping uterus contract after deliveryD:increasing the bond between babies and their mothers答案:ABCD2.Which is not the benefit of breastfeeding for babies?A:providing nutrientsB:providing genetic codesC:reducing baby’s risk of sudden infant death syndromeD:providing antibodies答案:B3.The duration of a feeding is usually on each breast.A:about five minsB:five to ten minsC:fifteen to twenty minsD:ten to fifteen mins答案:D4.When do health professionals recommend beginning breastfeeding?A:when the mother begins producing milkB:when the baby is cryingC:within the first hour of a baby’s lifeD:after the mother has a full rest答案:C5.Breastfeeding, also known as , is the feeding of babies and young childrenwith milk from a woman’s breast.A:milkingB:sucklingC:feedingD:nursing答案:D第五章测试1.Puberty which starts earlier than normal is known as __________?A:bad pubertyB:good pubertyC:precocious pubertyD:normal puberty答案:C2.What is the average age at which girls in the 19th century reached puberty?A:19B:18C:15D:13答案:C3.What is the major landmark of puberty for females ?A:beginning of menstruationB:beginning of growingC:irritabilityD:anxiety答案:A4.The genetic association of timing is strongest between ___________?A:mother and daughterB:father and sonC:Father and daughterD:mother and son答案:A5.From which language does the term puberty derive from?A:FrenchB:GermanC:LatinD:English答案:C第六章测试1.Periods may occasionally start as young as___________ years old and still beconsidered normal.A:7B:10C:8D:6答案:C2.The first period usually begins _____________.A:between10 and 16 years of ageB:between 10 and 12 years of ageC:between 12 and15 years of ageD:between 15 and 16 years of age答案:C3. A menstrual cycle is counted from_____________ to the first day of the nextperiod.A:the last day of the periodB:the second day of the periodC:the first day of the periodD:the last but one day of the period答案:C4.When you menstruate, your body sheds the __________of the uterus (womb).A:liningB:bloodC:hormonesD:eggs答案:A5.Menstruation is a woman’s _____________ bleeding.A:monthlyB:yearlyC:irregularD:weekly答案:A第七章测试1.During menopause, women often experience __________which often stopoccurring after a year or two.A:weight lossB:hot flashesC:diseasesD:growth spurt答案:B2.Menopause which stems from surgery, treatment of a disease, or an illness iscalled ___________.A:medical menopauseB:abnormal menopauseC:induced menopauseD:ill menopause答案:C3.Menopause may also be defined by a decrease in hormone production bythe ____________.A:glandsB:ovariesC:brainD:wombs答案:B4.Menopause is the time in most women’s lives when _______ stoppermanently.A:pregnancyB:menstrual periodsC:hormonesD:growth答案:B5.From which language does the word menopause derive from?A:FrenchB:GermanC:GreekD:English答案:C第八章测试1.At some point in life, often in the 30’s, the tell-tale signs of aging begin to beapparentA:20’sB:30’sC:40’sD:50’s答案:B2.From which moment, each of our cells—and, hence, our tissues and organs—begins a process of aging?A:childhoodB:conceptionC:pubertyD:infancy答案:B3.Of the roughly 150,000 people who die each day across the globe, about_______________ die from age-related causes.A:two thirdsB:two fourthsC:one thirdD:one fourth答案:A4.____________may slow with age, while knowledge of world events and wisdommay expandA:Eating timeB:leisure timeC:sleeping timeD:Reaction time答案:D5.In the broader sense, ageing can refer to single cells within an organismwhich have ceased __________.A:breakingB:seperatingC:workingD:dividing答案:D第九章测试1.Which is not the correct description of cerebral cortex?A:It consists of four lobesB:It is the inner layer of the cerebrumC:It is the seat of complex thoughtD:It is greatly enlarged in human brains答案:B2.The neurons in cerebrum are connected by trillions of connections, or_________.A:axolemmaB:axoplasmC:synapsesD:axon答案:C3.The cerebrum contains about 86 billion nerve cells (neurons) – the ______.A:green matterB:white matterC:gray matterD:black matter答案:C4.The cerebrum makes up _____ percent of the brain’s weight.A:95%B:80%C:85%D:90%答案:C5.The human brain makes up about ____ percent of a human’s body weight.A:1%B:3%C:4%D:2%答案:D第十章测试1.The blood pressure in the _____ is the same as the pressure measured in thearm.A:right ventricleB:left atriumC:right atriumD:left ventricle答案:D2.The right atrium and right ventricle together make up the “right heart”, andthe left atrium and the left ventricle make up the “left heart”. The wall ofmuscle separates the two sides of the heart is _______.A:septumB:tricuspid valveC:bicuspid valveD:semi-lunar valve答案:A3.Which of the following is the strongest chamber?A:left atriumB:right atriumC:right ventricleD:left ventricle答案:D4.Which of the following receives blood from the veins.A:left atriumB:right atriumC:right ventricleD:left ventricle答案:B5.The cardiovascular system consists of ____________.A:veinsB:heartC:arteriesD:kidney答案:ABC第十一章测试1.The respiratory system is divided into two parts:A:left branch; right branchB:upper respiratory branch; lower respiratory branchC:left tract; right tractD:upper respiratory tract; lower respiratory tract答案:D2.The left lung in humans is little bit ________ than the right lung.A:smallerB:upperC:lowerD:bigger答案:A3.The left human lung contains only two lobes.A:3B:5C:2D:4答案:C4.The right human lung has three lobes.A:4B:3C:2D:5答案:B5.The lungs of the humans are filled with about ______ air and _____ tissue.A:90%; 10%B:80%; 10%C:10%; 90%D:50%; 50%答案:A第十二章测试1.Mechanical digestion is the physical process of preparing the food for ________and involves chewing, mixing, churning, and segmentationA:chemical digestionB:propulsionC:defecationD:absorption答案:A2._________ moves food through the alimentary canal and includes bothswallowing and peristalsis.A:IngestionB:SwallowingC:PropulsionD:Digestion答案:C3.___________ is the act of putting food into the mouth.A:EatingB:ChewingC:InputtingD:Ingestion答案:D4.The digestive tract in an adult is about _______ long. Each of the organs shownabove contributes to the digestive process in several unique ways.A:30 metersB:30 feetC:20 feetD:20 meters答案:B5.The organs of the digestive system are located within a tube called the_____________.A:digestive systemB:tracheaC:stomachD:alimentary canal答案:D第十三章测试1.Who are the people at higher risk of influenza?A:those living with chronic conditionsB:pregnant women and young infantsC:those aged 65 and overD:indigenous people over 15答案:ABCD2.Which symptoms indicate that patient should seek immediate medical care?A:severe dehydrationB:breathing difficultiesC:chest painD:bluish skin and lips答案:ABCD3.The complications of influenza include .A:neurological complicationsB:cardiac complicationsC:secondary infectionsD:pneumonia答案:ABCD4.Which is not the typical symptom of influenza?A:runny or stuffy noseB:fatigue an tirednessC:headache and feverD:stomach ache答案:D5.Flu is a contagious respiratory illness caused by influenza viruses thatinfect .A:lungsB:the noseC:the throatD:all of other answer答案:D第十四章测试1.Which is not one of the uncontrollable risk factors of strokes?A:Sleep apneaB:Increasing ageC:Prior strokeD:Gender答案:A2.Which is not one of the controllable risk factors of strokes?A:High cholesterolB:Excessive alcohol intakeC:Physical inactivity and obesityD:Heredity and race答案:D3.How severe the stroke is depends on .A:how seriously the brain has been damagedB:how high the blood pressure isC:how changeable the weather isD:how much of the brain tissue dies答案:D4. A stroke occurs when .A:the brain is seriously damagedB:the blood pressure is extremely highC:the blood supply to the brain is blocked or reducedD:the weather changes frequently答案:C5.Stroke symptoms include .A:sudden trouble seeing in one or both eyesB:sudden confusion, trouble speaking, or understandingC:sudden numbness or weakness of face, arm or legD:sudden trouble walking, dizziness, loss of balance or coordination答案:ABCD第十五章测试1.Which of the following may be a reason of Type 2 diabetes?A:family history of type 2 diabetesB:a poor dietC:overweightD:adequate exercise答案:ABC2.Of all the patients with diabetes, only ____ of the patients have type 1 diabetesand the remaining ____ have type 2 diabetes.A:50%; 50%B:10%; 90%C:20%; 80%D:30%; 70%答案:B3.If you are a woman with type 1 diabetes and your child was born before youwere 25, your child’s risk is _______.A:1 in 4B:1 in 25C:1 in 100D:1 in 17答案:B4.Which of the following are noninsulin dependent diabetes.A:AODMB:NIDDMC:LADAD:IDDM答案:AB5.If a lean boy of 11 is diagnosed with diabetes, it is most likely to be ________.A:NIDDMB:AODMC:LADAD:IDDM答案:D。
Lecture Notes on CMB Theory:From Nucleosynthesis to RecombinationbyWayne Hua r X i v :0802.3688v 1 [a s t r o -p h ] 25 F eb 2008ContentsCMB Theory from Nucleosynthesis to Recombination page1 1Introduction1 2Brief Thermal History12.1Nucleosynthesis and Prediction of the CMB12.2Thermalization and Spectral Distortions42.3Recombination63Temperature Anisotropy from Recombination93.1Anisotropy from Inhomogeneity103.2Acoustic Oscillation Basics133.3Gravito-Acoustic Oscillations183.4Baryonic Effects223.5Matter-Radiation Ratio243.6Damping253.7Information from the Peaks274Polarization Anisotropy from Recombination324.1Statistical Description334.2EB Harmonic Description344.3Thomson Scattering354.4Acoustic Polarization364.5Gravitational Waves375Discussion37iiCMB Theory from Nucleosynthesis to Recombination1IntroductionThese lecture notes comprise an introduction to the well-established physics and phenomenology of the cosmic microwave background(CMB)between big bang nucleosynthesis and recombination.We take our study through recombination since most of the temperature and polarization anisotropy observed in the CMB formed during the recombination epoch when free electrons became bound into hydrogen and helium.The other reason for considering only this restricted range from nucleosynthesis to recombination is that these notes are meant to complement the other lectures of the XIX Canary Island Winter School of Astrophysics.While they are self-contained and complete in and of themselves,they omit important topics that will be covered elsewhere in this volume:namely inflation(Sabino Matarrese), observations(Bruce Partridge),statistical analysis(Licia Verde),secondary anisotropy(Matthias Bartelmann),and non-Gaussianity(Enrique Martinez-Gonzalez).Furthermore the approach taken here of introducing only as much detail as necessary to build physical intuition is more suitable as a general overview rather than a rigorous treatment for training specialists.As such these notes complement the more formal lecture notes for the Trieste school which may anachronistically be viewed as a continuation of these notes in the same notation(Hu 2003).The outline of these notes are as follows.We begin in§2with a brief thermal history of the CMB. We discuss the temperature and polarization anisotropy and acoustic peaks from recombination in §3-4and conclude in§5.We take units throughout with¯h=c=k B=1and illustrate effects in the standard cosmological constant cold dark matter universe with adiabatic inflationary initial conditions(ΛCDM).2Brief Thermal HistoryIn this section,we discuss the major events in the thermal history of the CMB.We begin in§2.1 with the formation of the light elements and the original prediction of relic radiation.We continue in§2.2with the processes that thermalize the CMB into a blackbody.Finally in§2.3,we discuss the recombination epoch where the main sources of temperature and polarization anisotropy lie.2.1Nucleosynthesis and Prediction of the CMBLet us begin our brief thermal history with the relationship between the CMB and the abundance of light elements established at an energy scale of102keV,time scale of a few minutes,temperature123 minutes: nucleosynthesisfew months: thermalizationFig.1.A brief thermal history:nucleosynthesis,thermalization,recombination and reionization.Adapted from Hu and White(2004).of109K and redshift of z∼108−109.This is the epoch of nucleosynthesis,the formation of the light elements.The qualitative features of nucleosynthesis are set by the low baryon-photon number density of our universe.Historically,the sensitivity to this ratio was used by Gamow and collaborators in the late1940’s to predict the existence and estimate the temperature of the CMB.Its modern use is the opposite:with the photon density well measured from the CMB spectrum,the abundance of light elements determines the baryon density.At the high temperature and densities of nucleosynthesis,radiation is rapidly thermalized to a perfect black body and the photon number density is afixed function of the temperature nγ∝T3 (see below).Apart from epochs in which energy from particle annihilation or other processes is dumped into the radiation,the baryon-photon number density ratio remains constant.Likewise nuclear statistical equilibrium,while satisfied,makes the abundance of the light elements of mass number A follow the expectations of a Maxwell-Boltzmann distribution for the phase space occupation numberf A=e−(m A−µA)/T e−p2A/2m A T,(1) where p A is the particle momentum,m A is the rest mass,andµA is the chemical ly their number densityn A≡g A d3pA(2π)3f A=g A(m A T2π)3/2e(µA−m A)/T.(2)Here g A is the degeneracy factor.In equilibrium,the chemical potentials of the various elements are related to those of the proton and neutron byµA=Zµp+(A−Z)µn,(3)CMB Theory from Nucleosynthesis to Recombination3 where Z is the charge or number of ing this relation,the abundance fractionX A≡A n An b=A5/2g A2−A2πTm b3/22ζ(3)ηbγπ2A−1e B A/T X Z p X A−Zn,(4)where X p and X n are the proton and neutron abundance,ζ(3)≈1.202,and n b is the baryon number density.The two controlling quantities are the binding energyB A=Zm p+(A−Z)m n−m A,(5)and the baryon-photon number density ratioηbγ=n b/nγ.That the latter number is of order10−9 in our universe means that light elements form only well after the temperature has dropped below the binding energy of each species.Nuclear statistical equilibrium holds until the reaction rates drop below the expansion rate.At this point,the abundance freezes out and remains constant. Gamow’s back of the envelope estimate(Gamow1948,refined by Alpher and Herman1948)was to consider the neutron capture reaction that forms deuteriumn+p↔d+γ(6)with a binding energy of B2=2.2MeV.Given Eqn.(4)X2=3π24πTm b3/2ηbγζ(3)e B2/T X p X n,(7)a low baryon-photon ratio,and X n≈X p≈1/2for estimation purposes,the critical temperature for deuterium formation is T∼109K.In other words the low baryon-photon ratio means that there are sufficient numbers of photons to dissociate deuterium until well below T∼B2.Note that this condition is only logarithmically sensitive to the exact value of the baryon-photon ratio chosen for the estimate and so the reasoning is not circular.Furthermore,that we observe deuterium at all and not all helium and heavier elements means that the reaction must have frozen out at near this temperature.Given the thermally averaged cross section ofσv ≈4.6×10−20cm3s−1,(8) the freezeout conditionn b σv ≈H≈t−1,(9) and the time-temperature relation t(T=109K)≈180s from the radiation dominated Friedmann equation,we obtain an estimate of the baryon number densityn b(T=109K)∼1.2×1017cm−3.(10) Comparing this density to the an observed current baryon density and requiring that n b∝a−3and T∝a−1yields the current temperature of the thermal background.For example,taking the modern value ofΩb h2≈0.02and n b(a=1)=2.2×10−7cm−3yields the rough estimateT(a=1)≈12K.(11) This value is of the same order of magnitude as the observed CMB temperature2.725K as well as the original estimates(Alpher and Herman1948;Dicke et al.1965).Modern day estimates of the baryon-photon ratio also rely on deuterium(e.g.Tytler et al.2000).We shall see that the CMB has its own internal measure of this ratio from the acoustic peaks.Agreement between the nucleosynthesis4p /T init0.10-0.1-0.22ptonization process.Energy injected into the CMB through heating of the electrons is thermalized by Compton scattering.Under the Kompaneets equation,a y -distortion first forms as low frequency photons gain energy from the electrons.After multiple scatterings the distribution is thermalized to a chemical potential or µ-distortion.Adapted from Hu (1995).and acoustic peak measurements argue that the baryon-photon ratio has not changed appreciably since z ∼108.2.2Thermalization and Spectral DistortionsBetween nucleosynthesis and recombination,processes that create and destroy photons and hence thermalize the CMB fall out of equilibrium.The lack of spectral distortions in the CMB thus constrains any process that injects energy or photons into the plasma after this epoch.In a low baryon-photon ratio universe,the main thermalization process is double,also known as radiative,Compton scatteringe −+γ↔e −+γ+γ.(12)The radiative Compton scattering rate becomes insufficient to maintain a blackbody at a redshift of (Danese and de Zotti 1982)z therm =2.0×106(1−Y p /2)−2/5 Ωbh 20.02 −2/5(13)corresponding to a time scale of order a few months.After this redshift,energy or photon injection appears as a spectral distortion in the spectrum of the CMB.The form of the distortion is determined by Compton scatteringe −+γ↔e −+γ,(14)since it is still sufficiently rapid compared with respect to the expansion while hydrogen remains ionized.Because a blackbody has a definite number density of photons at a given temperature,CMB Theory from Nucleosynthesis to Recombination 5ΔT /T e-0.05-0.1-0.15p /T eFig.3.Low frequency thermalization by bremsstrahlung.Creation and absorption of photons at low frequencies by bremsstrahlung bring a chemical potential distortion back to blackbody at the electron temperature T e between z K and recombination.Adapted from Hu and Silk (1993).energy exchange via Compton scattering alone can only produce a Bose-Einstein spectrum for the photon distribution functionf =1e (E −µ)/T −1(15)with µdetermined by the conserved number density and temperature.The evolution to a Bose-Einstein distribution is determined by solving the Kompaneets equation (Zeldovich and Sunyaev 1969).The Kompaneets equation is Boltzmann equation for Compton scattering in a homogeneous medium.It includes the effects of electron recoil and the second order Doppler shift that exchange energy between the photons and electrons.If energy is injected into the plasma to heat the electrons,Comptonization will try to redistribute the energy to the CMB.Consequently the first step in Comp-tonization is a so called “y distortion”in the spectrum as low energy photons in the Rayleigh Jeans tail of the CMB gain energy from the second order Doppler shift (see Fig.2).After multiple scatterings,the spectrum settles into the Bose-Einstein form with a “µdistor-tion.”The transition occurs when the energy-transfer weighted optical depth approaches unity,i.e.τK (z K )=4 dtn e σT T e /m e =1where n e is the electron density σT is the Thomson cross section,T e is the electron temperature and m e is the electron massz K ≈5.1×104(1−Y p /2)−1/2 Ωbh 20.02 −1/2.(16)Above this redshift energy injection creates a µdistortion,below a y distortion.At very low frequencies,bremsstrahlunge −+p ↔e −+p +γ(17)is still efficient in creating and absorbing photons.In Fig.3we show the how a µ-distortion continues6frequency (cm -1 )GHzerror x 505024681012101520200400600Fig.4.CMB spectrum from FIRAS.No spectral distortions from a blackbody have been discovered to date.to evolve until recombination which brings the low frequency spectrum back to a blackbody but now at the electron temperature.The best limits to date are from COBE FIRAS from intermediate to high frequencies:|µ|<9×10−5and |y |<1.5×10−5at 95%confidence (see Fig 4and Fixsen et al.1996).After subtracting out galactic emission,no spectral distortions of any kind are detected and the spectrum appears to be a perfect blackbody of ¯T=2.725±0.002K (Mather et al.1999).2.3RecombinationWhile the recombination processp +e −↔H +γ,(18)is rapid compared to the expansion,the ionization fraction obeys an equilibrium distribution just like that considered for light elements for nucleosynthesis or the CMB spectrum thermalization.As in the former two processes,the qualitative behavior of recombination is determined by the low baryon-photon ratio of the universe.Taking number densities of the Maxwell-Boltzmann form of Eqn.(2),we obtainn p n e n H ≈e −B/Tm e T 2π 3/2e (µp +µe −µH )/T ,(19)where B =m p +m e −m H =13.6eV is the binding energy and we have set g p =g e =12g H =2.Given the vanishingly small chemical potential of the photons,µp +µe =µH in equilibrium.Next,defining the ionization fraction for a hydrogen only plasman p =n e =x e n b ,n H =n b −n p =(1−x e )n b ,(20)CMB Theory from Nucleosynthesis to Recombination 7Saha 2-levelx e i o n i z a t i o n f r a c t i o n scale factor aredshift z10-410-310-210-1110-310310410210-2Fig.5.Hydrogen recombination in Saha equilibrium vs.the calibrated 2-level calculation of RECFAST.The features before hydrogen recombination are due to helium recombination.we can rewrite Eqn.(19)as the Saha equation n e n pn H n b =x 2e 1−x e =1n b m e T 2π 3/2e −B/T .(21)Recombination occurs at a temperature substantially lower than T =B again because of the low baryon-photon ratio of the universe.We can see this by rewriting the Saha equation in terms of the photon number densityx 2e 1−x e =e −B/kT π1/225/2ηbγζ(3) m e c 2kT 3/2.(22)Because ηbγ∼10−9,the Saha equation implies that the medium only becomes substantially neutral at a temperature of T ≈0.3eV or at a redshift of z ∗∼103.At this point,there are not enough photons in the even in the Wien tail above the binding energy to ionize hydrogen.We plot the Saha solution in Fig.5.Near the epoch of recombination,the recombination rates become insufficient to maintain ionization equilibrium.There is also a small contribution from helium recombination that must be added.The current standard for following the non-equilibrium ionization history is RECFAST (Seager et al.2000)which employs the traditional two-level atom calculation of Peebles (1968)but alters the hydrogen case B recombination rate αB to fit the results of a multilevel atom.More specifically,RECFAST solves a coupled system of equations for the ionization fraction x i in singly ionized hydrogen and helium (i =H,He)dx i d ln a =αB C i n Hp H[s (x max −x i )−x i x e ],(23)where n Hp =(1−Y p )n b is the total hydrogen plus proton number density accounting for the helium8mass fraction Y p,x e≡n e/n Hp= xi is the total ionization fraction,n e is the free electron density,x max is the maximum x i achieved through full ionization,s=βn Hpe−B1s/T b,C−1 i =1+βαB e−B2s/T bΛα+Λ2s1s,β=g rat Tbm e2π3/2,(24)with g rat the ratio of statistical weights,T b the baryon temperature,B L the binding energy of the L th level,Λαthe rate of redshifting out of the Lyman-αline corrected for the energy difference between the2s and2p statesΛα=1π2(B1s−B2p)3e−(B2s−B2p)/T bH(x max−x i)n Hp(25)andΛ2s1s as the rate for the2photon2s−1s transition.For reference,for hydrogen B1s=13.598eV, B2s=B2p=B1s/4,Λ2s1s=8.22458s−1,g rat=1,x max=1.For helium B1s=24.583eV,B2s= 3.967eV,B2p=3.366eV,Λ2s1s=51.3s−1,g rat=4,x max=Y p/[4(1−Y p)].Note that if the recombination rate is faster than the expansion rateαB C i n Hp/H 1,the ion-ization solutions for x i reach the Saha equilibrium dx i/d ln a=0.In this case s(x max−x i)=x i x e orx i=12(x ei+s)2+4sx max−(x ei+s)(26)=x max1−x ei+x maxs1−x ei+2x maxs+...,where x ei=x e−x i is the ionization fraction excluding the species.The recombination of hydrogenic doubly ionized helium is here handled purely through the Saha equation with a binding energy of 1/4the B1s of hydrogen and x max=Y p/[4(1−Y p)].The case B recombination coefficients as a function of T b are given in Seager et al.(2000)as is the strong thermal coupling between T b and T CMB.The multilevel-atom fudge that RECFAST introduces is to replace the hydrogenαB→1.14αB independently of cosmology.While this fudge suffices for current observations,which approach the ∼1%level,the recombination standard will require improvement if CMB anisotropy predictions are to reach an accuracy of0.1%(e.g.Switzer and Hirata2007;Wong et al.2007).The phenomenology of CMB temperature and polarization anisotropy is primarily governed by the redshift of recombination z∗=a−1∗−1when most of the contributions originate.This redshift though carries little dependence on standard cosmological parameters.This insensitivity follows from the fact that recombination proceeds rapidly once B1s/T b has reached a certain threshold as the Saha equation illustrates.Defining the redshift of recombination as the epoch at which the Thomson optical depth during recombination(i.e.excluding reionization)reaches unity,τrec(a∗)=1,afit to the recombination calculation gives(Hu2005)a−1∗≈1089Ωm h20.140.0105Ωb h20.024−0.028,(27)around afiducial model ofΩm h2=0.14andΩb h2=0.024.The universe is known to be reionized at low redshifts due to the lack of a Gunn-Peterson trough in20406080100[ l (l +1)C l /2π ]1/2 (μK)64ºFig.6.From temperature maps to power spectrum.The original temperature fluctuation map (top left)corresponding to a simulation of the power spectrum (top right)can be band filtered to illustrate the power spectrum in three characteristic regimes:the large-scale gravitational regime of COBE,the first acoustic peak where most of the power lies,and the damping tail where fluctuations are dissipated.Adapted from Hu and White (2004).quasar absorption spectra.Moreover,large angle CMB polarization detections (see Fig.19)suggest that this transition back to full ionization occurred around z ∼10leaving an extended neutral period between recombination and reionization.3Temperature Anisotropy from RecombinationSpatial variations in the CMB temperature at recombination are seen as temperature anisotropy by the observer today.The temperature anisotropy of the CMB was first detected in 1992by the COBE DMR instrument (Smoot et al.1992).These corresponded to variations of order ∆T/T ∼10−5across 10◦−90◦on the sky (see Fig.6).Most of the structure in the temperature anisotropy however is associated with acoustic oscillations of the photon-baryon plasma on ∼1◦scales.Throughout the 1990’s constraints on the location of the first peak steadily improved culminating with the determinations of the TOCO (Miller et al.1999),Boomerang,(de Bernardis et al.2000)and Maxima-1(Hanany et al.2000)experiments.Currently from WMAP (Spergel et al.2007)and ground based experiments,we have precise measurements of the first five acoustic peaks (see Fig.7).Primary fluctuations beyond this scale (below ∼10 )are damped by Silk damping (Silk 1968)as verified observationally first by the CBI experiment (Padin et al.2001).In this section,we deconstruct the basic physics behind these phenomena.We begin with the geometric projection of temperature inhomogeneities at recombination onto the sky of the observer in §3.1.We continue with the basic equations of fluid mechanics that govern acoustic phenomena in §3.2.We add gravitational (§3.3),baryonic (§3.4),matter-radiation (§3.5),and dissipational (§3.6)l (l +1)C l /2π (μK )2lFig.7.Temperature power spectrum from recent measurements from WMAP and ACBAR along with the best fit ΛCDM model.The main features of the temperature power spectrum including the first 5acoustic peaks and damping tail have now been measured.Adapted from Reichardt et al.(2008)..effects in the sections that follow.Finally we put these pieces back together to discuss the information content of the acoustic peaks in §3.7.3.1Anisotropy from InhomogeneityGiven that the CMB radiation is blackbody to experimental accuracy (see Fig.4),one can characterize its spatial and angular distribution by its temperature at the position x of the observer in the direction ˆnon the observer’s sky f (ν,ˆn ,x )=[exp(2πν/T (ˆn ;x )−1]−1,(28)where ν=E/2πis the observation frequency.The hypothetical observer could be an electron in the intergalactic medium or the true observer on earth or L2.When the latter is implicitly meant,we will take x =0.We will occasionally suppress the coordinate x when this position is to be understood.For statistically isotropic,Gaussian random temperature fluctuations a harmonic description is more efficient than a real space description.For the angular structure at the position of the observer,the appropriate harmonics are the spherical harmonics.These are the eigenfunctions of the Laplace operator on the sphere and form a complete basis for scalar functions on the skyΘ(ˆn )=T (ˆn )−¯T ¯T = mΘ m Y m (ˆn ).(29)For statistically isotropic fluctuations,the ensemble average of the temperature fluctuations are described by the power spectrumΘ m ∗Θ m =δ δmm C .(30)Moreover,the power spectrum contains all of the statistical information in the field if the fluctuations are Gaussian.Here C is dimensionless but is often shown with units of squared temperature,e.g.µK 2,by multiplying through by the background temperature today ¯T.The correspondence between angular size and amplitude of fluctuations and the power spectrum is shown in Fig.6.Let us begin with the simple approximation that the temperature field at recombination is isotropicn D *recombinationobserverFig.8.From inhomogeneity to anisotropy.Temperature inhomogeneities at recombination are viewed at a distance D ∗as anisotropy on the observer’s sky.but inhomogeneous and the anisotropy viewed at the present is due to the observer seeing different portions of the recombination surface in different directions (see Fig.8).We will develop this picture further in the following sections with gravitational redshifts,dipole or Doppler anisotropic sources,the finite duration of recombination,and polarization.Under this simple instantaneous recombination approximation,the angular temperature fluctuation distribution is simply a projection of the spatial temperature fluctuationΘ(ˆn )=dD Θ(x )δ(D −D ∗),(31)where D = dz/H is the comoving distance and D ∗denotes the distance a CMB photon travels from recombination.Here Θ(x )=(T (x )−¯T)/¯T is the spatial temperature fluctuation at recombi-nation.Note that the cosmological redshift does not appear in the temperature fluctuation since the background and fluctuation redshift alike.The spatial power spectrum at recombination can be likewise be described by its harmonic modes.In a flat geometry,these are Fourier modesΘ(x )= d 3k (2π)3Θ(k )e i k ·x .(32)More generally they are the eigenfunctions of the Laplace operator on the three dimensional space with constant curvature of a general Friedmann-Robertson-Walker metric (see e.g.Hu 2003).For a statistically homogeneous spatial distribution,the two point function is described by the power spectrumΘ(k )∗Θ(k ) =(2π)3δ(k −k )P (k ).(33)These relations tell us that the amplitude of the angular and spatial power spectra are related.A useful way of establishing this relation and quantifying the power in general is to describe the contribution per logarithmic interval to the variance of the respective fields:Θ(x )Θ(x ) = d 3k (2π)P (k )= d ln k k 3P (k )2π≡ d ln k ∆2T (k ).(34)A scale invariant spectrum has equal contribution to the variance per e-fold ∆2T =k 3P (k )/2π2=const.To relate this to the amplitude of the angular power spectrum,we expand equation (31)in Fourier modesΘ(ˆn )= d 3k (2π)3Θ(k )e i k ·D ∗ˆn .(35)The Fourier modes themselves can be expanded in spherical harmonics with the relatione i k D ∗·ˆn =4πm i j (kD ∗)Y ∗ m (ˆk )Y m (ˆn ),(36)where j is the spherical Bessel function.Extracting the multipole moments,we obtainΘ m = d 3k (2π)3Θ(k )4πi j (kD ∗)Y m (k ).(37)We can then relate the angular and spatial two point functions (30)and (33) Θ∗ m Θ m =δ δmm 4π d ln k j 2 (kD ∗)∆2T (k )=δ δmm C .(38)Given a slowly varying,nearly scale invariant spatial power spectrum we can take ∆2T out of the integral and evaluate it at the peak of the Bessel function kD ∗≈ .The remaining integral can be evaluated in closed form ∞0j 2 (x )d ln x =1/[2 ( +1)]yielding the final resultC ≈2π ( +1)∆2T ( /D ∗).(39)Likewise even slowly varying features like the acoustic peaks of §3.2also mainly map to multipolesof ≈kD ∗due to the delta function like behavior of j 2.It is therefore common to plot the angular power spectrum asC ≡( +1)2πC ≈∆2T .(40)It is also common to plot C 1/2 ≈∆T ,the logarithmic contribution to the rms of the field,in units ofµK.Now let us compare this expression to the variance per log interval in multipole space:T (ˆn )T (ˆn ) =m m T ∗ m T m Y ∗ m (ˆn )Y m (ˆn )=C m Y ∗ m (ˆn )Y m (ˆn )= 2 +14πC .(41)For variance contributions from 1,2 +14πC ≈ d ln (2 +1)4πC ≈ d ln ( +1)2πC .(42)Thus C is also approximately the variance per log interval in angular space as well.3.2Acoustic Oscillation BasicsThomson Tight Coupling —To understand the angular pattern of temperature fluctuations seen by the observer today,we must understand the spatial temperature pattern at recombination.That in turn requires an understanding of the dominant physical processes in the plasma before recombination.Thomson scattering of photons offof free electrons is the most important process given its relatively large cross section (averaged over polarization states)σT =8πα23m 2e =6.65×10−25cm 2.(43)The important quantity to consider is the mean free path of a photon given Thomson scattering and a medium with a free electron density n e .Before recombination when the ionization fraction x e ≈1this density is given byn e =(1−Y p )x e n b=1.12×10−5(1−Y p )x e Ωb h 2(1+z )3cm −3.(44)The comoving mean free path λC is given byλ−1C ≡˙τ≡n e σT a ,(45)where the extra factor of a comes from converting physical to comoving coordinates and Y p is the primordial helium mass fraction.We have also represented this mean free path in terms of an scattering absorption coefficient ˙τwhere dots are conformal time η≡ dt/a derivatives and τis the optical depth.Near recombination (z ≈103,x e ≈1)and given Ωb h 2≈0.02,and Y p =0.24,the mean free path isλC ≡1˙τ∼2.5Mpc .(46)This scale is almost two orders of magnitude smaller than the horizon at recombination.On scales λ λC photons are tightly coupled to the electrons by Thomson scattering which in turn are tightly coupled to the baryons by Coulomb interactions.As a consequence,any bulk motion of the photons must be shared by the baryons.In fluid language,the two species have a single bulk velocity v γ=v b and hence no entropy generation or heat conduction occurs.Furthermore,the shear viscosity of the fluid is negligible.Shear viscosity is related to anisotropy in the radiative pressure or stress and rapid scattering isotropizes the photon distribution.This is also the reason why in equation (31)we took the photon distribution to be isotropic but inhomogeneous.We shall see that the fluid motion corrects this by allowing dipole =1anisotropy in the dis-tribution but no higher modes.It is only on scales smaller than the diffusion scale that radiative viscosity ( =2)and heat conduction becomes sufficiently large to dissipates the bulk motions of the plasma (see §3.6).Zeroth Order Approximation —To understand the basic physical picture,let us begin our discussion of acoustic oscillations in the tight coupling regime with a simplified system which we will refine as we progress.First let us ignore the dynamical impact of the baryons on the fluid motion.Given that the baryon and photon velocity are equal and the momentum density of a relativistic fluid is given by (ρ+p )v ,。
