A unified model of particle mass
GRE阅读高分考生分享备考提升诀窍
GRE阅读高分考生分享备考提升诀窍GRE阅读高分考生共享备考有用提升诀窍,我们一起来学习一下吧，下面我就和大家共享，来观赏一下吧。
GRE阅读高分考生共享备考有用提升诀窍GRE阅读练习要掌握时间平常练习GRE阅读，就要从掌握时间开头，这样才能更好的适应考试节奏。
详细来说，阅读复习掐时间读一篇文章，长文章1.5—2分钟，短文章1—1.5分钟，然后以平均每题1分钟的速度解完后面的题。
留意是“平均”,即你只要掌握在比如7题在7分钟内作完即可。
GRE阅读练习要学会时时总结不少人喜爱拿到练习备考材料就埋头苦练，对于自己做错的题目缺很少总结，最终就会消失同类题目一错再错的低效率重复劳动。
学会时时总结，对自己做错的每道题目都分析错误缘由，了解为什么会错，错在哪里。
才能有效提高做题效率，提升阅读水平。
GRE阅读练习要精度重点文章GRE阅读复习的时候，对于有些真题类或比较有代表性的题目文章最好不计时间地认真讨论一遍，主要讨论层次结构,起承转合,语言套路及选项特征等内容，对该类型的文章心中有数，之后遇到同类文章就能快速找出答题点快速解决难题。
GRE阅读练习学会分析题目和解题思路做完每道题，不论作对或作错,想一下此题的解题思路是什么,是否具有多种解题方案,自己距离某种解题方案还有什么缺陷或不足,什么样的方法最适合自己，最短的解题思路又是什么。
对于每道题的五个选项都找出对或错的理由来，肯定要是让自己信服的理由。
可能有人达到肯定高度觉得没必要,太费时,但是有些看来现在很友好的错误项只要稍加变动就会面目全非。
所以肯定要认真看过,找到它的弱点和难点才行。
以上就是一些GRE阅读快速提高的方法和技巧，大家在平常做题时可以善加利用，提高自己的备考效率，早日攻克GRE阅读难关。
GRE阅读练习每日一篇Classical physics defines the vacuum as a state of absence: a vacuum is said to exist in a region of space if there is nothing in it. In the quantum field theories that describe the physics of elementary particles, the vacuum becomes somewhat more complicated. Even in empty space, particles can appear spontaneously as a result of fluctuations of the vacuum. For example, an electron and a positron, or antielectron, can be created out of the void. Particles created in this way have only a fleeting existence; they are annihilated almost as soon as they appear, and their presence can never be detected directly. They are called virtual particles in order to distinguish them from real particles, whose lifetimes are not constrained in the same way, and which can be detected. Thus it is still possible to define that vacuum as a space that has no real particles in it.One might expect that the vacuum would always be the state of lowest possible energy for a given region of space. If an area is initially empty and a real particle is put into it, the total energy, it seems, should be raised by at least the energy equivalent of the mass of the added particle. A surprising result of some recent theoretical investigations is that this assumption is not invariably true. There are conditions under which the introduction of a real particle of finite mass into an empty region of space can reduce the total energy. If the reduction in energy is great enough, an electron and a positron will be spontaneously created. Under these conditions the electron and positron are not a result of vacuum fluctuations but are real particles, which exist indefinitely andcan be detected. In other words, under these conditions the vacuum is an unstable state and can decay into a state of lower energy; i.e., one in which real particles are created.The essential condition for the decay of the vacuum is the presence of an intense electric field. As a result of the decay of the vacuum, the space permeated by such a field can be said to acquire an electric charge, and it can be called a charged vacuum. The particles that materialize in the space make the charge manifest. An electric field of sufficient intensity to create a charged vacuum is likely to be found in only one place: in the immediate vicinity of a superheavy atomic nucleus, one with about twice as many protons as the heaviest natural nuclei known. A nucleus that large cannot be stable, but it might be possible to assemble one next to a vacuum for long enough to observe the decay of the vacuum. Experiments attempting to achieve this are now under way (under way: adv.进行中, 在行进).17. Which of the following titles best describes the passage as a whole?(A) The Vacuum: Its Fluctuations and Decay(B) The Vacuum: Its Creation and Instability(C) The Vacuum: A State of Absence(D) Particles That Materialize in the Vacuum(E) Classical Physics and the Vacuum18. According to the passage, the assumption that the introduction ofa real particle into a vacuum raises the total energy of that region of space has been cast into doubt by which of the following?(A) Findings from laboratory experiments(B) Findings from observational field experiments(C) Accidental observations made during other experiments(D) Discovery of several erroneous propositions in accepted theories(E) Predictions based on theoretical work19. It can be inferred from the passage that scientists are currently making efforts to observe which of the following events?(A) The decay of a vacuum in the presence of virtual particles(B) The decay of a vacuum next to a superheavy atomic nucleus(C) The creation of a superheavy atomic nucleus next to an intense electric field(D) The creation of a virtual electron and a virtual positron as a result of fluctuations of a vacuum(E) The creation of a charged vacuum in which only real electrons can be created in the vacuum’s region of space20. Physicists’ recent investigations of the decay of the vacuum, as described in the passage, most closely resemble which of the following hypothetical events in other disciplines?(A) On the basis of data gathered in a carefully controlled laboratory experiment, a chemist predicts and then demonstrates the physical properties of a newly synthesized polymer.(B) On the basis of manipulations of macroeconomic theory, an economist predicts that, contrary to accepted economic theory, inflation and unemployment will both decline under conditions of rapid economic growth.(C) On the basis of a rereading of the texts of Jane Austen’s novels, a literary critic suggests that, contrary to accepted literary interpretations. Austen’s plots were actually metaphors for political events in early nineteenth-century England.(D) On the basis of data gathered in carefully planned observations of several species of birds, a biologist proposes a modification in the accepted theory of interspecies competition.(E) On the basis of a study of observations incidentally recorded in ethnographers’ descriptions of non-Western societies, an anthropologist proposes a new theory of kinship relations.21. According to the passage, the author considers the reduction of energy in an empty region of space to which a real particle has been added to be(A) a well-known process(B) a frequent occurrence(C) a fleeting aberration(D) an unimportant event(E) an unexpected outcome22. According to the passage, virtual particles differ from real particles in which of the following ways?I. Virtual particles have extremely short lifetimes.II. Virtual particles are created in an intense electric field.III. Virtual particles cannot be detected directly.(A) I only(B) II only(C) III only(D) I and II only(E) I and III only23. The author’s assertions concerning the conditions that lead to the decay of the vacuum would be most weakened if which of the following occurred?(A) Scientists created an electric field next to a vacuum, but found that the electric field was not intense enough to create a charged vacuum.(B) Scientists assembled a superheavy atomic nucleus next to a vacuum, but found that no virtual particles were created in the vacuum’s region of space.(C) Scientists assembled a superheavy atomic nucleus next to a vacuum, but found that they could not then detect any real particles in the vacuum’s region of space.(D) Scientists introduced a virtual electron and a virtual positron into a vacuum’s region of space, but found that the vacuum did not thenfluctuate.(E) Scientists introduced a real electron and a real positron into a vacuum’s region of space, but found that the total energy of the space increased by the energy equivalent of the mass of the particles.Simone de Beauvoir’s work greatly influenced BettyFriedan’s—Indeed, made it possible. Why, then, was it Friedan who became the prophet of women’s emancipation in the United States? Political conditions, as well as a certain anti-intellectual bias, prepared Americans and the American media to better receive Friedan’s deradicalized and highly pragmatic The Feminine Mystique, published in 1963, than Beauvoir’s theoretical reading of women’s situation in The Second Sex. In 1953 when The Second Sex first appeared in translation in the United States, the country had entered the silent, fearful fortress of the anticommunist McCarthy years (1950-1954), and Beauvoir was suspected of Marxist sympathies. Even The Nation, a generally liberal magazine, warned its readers against “certain political leanings” of the author. Open acknowledgement of the existence of women’s oppression was too radical for the United States in the fifties, and Beauvoir’s conclusion, that change in women’s economic condition, though insufficient by itself, “remains the basic factor” in improving women’s situation, was particularly unacceptable.24. According to the passage, one difference between The Feminine Mystique and The Second Sex is that Friedan’s book(A) rejects the idea that women are oppressed(B) provides a primarily theoretical analysis of women’s lives(C) does not reflect the political beliefs of its author(D) suggests that women’s economic condition has no impact ontheir status(E) concentrates on the practical aspects of the questions of women’s emancipation25. The author quotes from The Nation most probably in order to(A) modify an earlier assertion(B) point out a possible exception to her argument(C) illustrate her central point(D) clarify the meaning of a term(E) cite an expert opinion26. It can be inferred from the passage that which of the following is not a factor in the explanation of why The Feminine Mystique was received more positively in the United States than was The Second Sex?(A) By 1963 political conditions in the United States had changed.(B) Friedan’s book was less intellectual and abstract than Beauvoir’s.(C) Readers did not recognize the powerful influence of Beauvoir’s book on Friedan’s ideas.(D) Friedan’s approach to the issue of women’s emancipation was less radical than Beauvoir’s.(E) American readers were more willing to consider the problem of the oppression of women in the sixties than they had been in the fifties.27. According to the passage, Beauvoir’s book asserted that the status of women(A) is the outcome of political oppression(B) is inherently tied to their economic condition(C) can be best improved under a communist government(D) is a theoretical, rather than a pragmatic, issue(E) is a critical area of discussion in Marxist economic theory答案：17-27：AEBBEECECCB。
介绍牛顿1分钟英文作文
介绍牛顿1分钟英文作文Isaac Newton was a renowned English mathematician, physicist, astronomer, and natural philosopher who lived during the 17th century. His contributions to the scientific revolution are considered among the most significant in the history of science. In this essay, we will explore the life and achievements of this remarkable individual.Born on January 4, 1642, in Woolsthorpe Manor, Lincolnshire, England, Newton grew up in a time of great intellectual and scientific advancements. As a young boy, he exhibited a keen interest in the natural world, often tinkering with mechanical devices and conducting experiments. His curiosity and analytical mind would later become the driving force behind his groundbreaking discoveries.One of Newton's most famous contributions was his formulation of the three laws of motion, which laid the foundation for classical mechanics. The first law, also known as the law of inertia, states that an object at rest will remain at rest, and an object in motion will continue to move at a constant velocity unless acted upon by an external force. The second law, which relates the acceleration of an object to the net force acting upon it, is often expressed as theequation F = ma, where F represents the force, m is the mass of the object, and a is the acceleration. The third law, often referred to as the action-reaction law, states that for every action, there is an equal and opposite reaction.In addition to his work on mechanics, Newton made significant contributions to the field of optics. He conducted extensive experiments with light, leading to the development of the reflecting telescope and the understanding of the nature of white light. Newton's work on the spectrum of light and the properties of prisms laid the groundwork for the study of color and the wave-particle duality of light.Another major achievement of Newton was his work in the field of mathematics. He is credited with the development of calculus, a branch of mathematics that deals with the study of rates of change and the accumulation of quantities. Newton's work on calculus, which he developed independently from Gottfried Leibniz, revolutionized the way scientists and mathematicians approached problems involving motion, change, and the behavior of continuous systems.Newton's scientific contributions were not limited to the fields of mechanics, optics, and mathematics. He also made significant advances in the understanding of gravity and the motion of celestialbodies. His law of universal gravitation, which states that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them, provided a unified explanation for the motion of the planets, the tides, and the behavior of falling objects on Earth.Despite his many accomplishments, Newton's life was not without its challenges. He faced periods of poor health, personal struggles, and conflicts with other scientists over the priority of various discoveries. However, his unwavering dedication to his work and his insatiable curiosity kept him driven to push the boundaries of human knowledge.In the later years of his life, Newton held various prestigious positions, including serving as the Master of the Royal Mint and being elected as a member of the Parliament of England. He was also knighted by Queen Anne in 1705, a recognition of his immense contributions to the scientific community.Newton's legacy continues to be felt in the modern world, as his theories and discoveries form the foundation of much of our understanding of the physical universe. His work has inspired countless scientists, engineers, and thinkers, and his influence can be seen in fields ranging from astronomy and physics to economics andcomputer science.In conclusion, Isaac Newton was a true giant of science, whose contributions have had a profound and lasting impact on our understanding of the natural world. His unwavering dedication to the pursuit of knowledge and his ability to make groundbreaking discoveries have cemented his place as one of the most influential figures in the history of science.。
P41
UNIVERSITY OF CAMBRIDGE INTERNATIONAL EXAMINATIONSGeneral Certificate of Education Advanced Level*7303645500*PHYSICS9702/41Paper 4 A2 Structured Questions May/June 20101 hour 45 minutesCandidates answer on the Question Paper.No Additional Materials are required.READ THESE INSTRUCTIONS FIRSTWrite your Centre number, candidate number and name on all the work you hand in.Write in dark blue or black pen.Y ou may use a soft pencil for any diagrams, graphs or rough working.Do not use staples, paper clips, highlighters, glue or correction fluid.DO NOT WRITE IN ANY BARCODES.Answer all questions.Y ou may lose marks if you do not show your working or if you do not use appropriate units.At the end of the examination, fasten all your work securely together.The number of marks is given in brackets [ ] at the end of each question or part question.For Examiner’s Use 1 2 3 4 5 6 7 8 9101112TotalDataspeed of light in free space, c = 3.00 × 108m s–1 permeability of free space, μ0= 4π × 10–7H m–1 permittivity of free space, ε0= 8.85 × 10–12F m–1 elementary charge, e = 1.60 × 10–19 Cthe Planck constant, h = 6.63 × 10–34J s unified atomic mass constant, u = 1.66 × 10–27 kg= 9.11 × 10–31 kgrest mass of electron, me= 1.67 × 10–27 kgrest mass of proton, mpmolar gas constant, R = 8.31 J K–1 mol–1= 6.02 × 1023 mol–1the Avogadro constant, NAthe Boltzmann constant, k = 1.38 × 10–23J K–1 gravitational constant, G = 6.67 × 10–11N m2 kg–2 acceleration of free fall, g = 9.81 m s–2© UCLES 20109702/41/M/J/109702/41/M/J/10© UCLES 2010[Turn overFormulaeuniformly accelerated motion, s = ut + at 2v 2 = u 2 + 2as work done on/by a gas, W = p ⌬Vgravitational potential, φ = – Gmrhydrostatic pressure, p = ρgh pressure of an ideal gas, p =Nm V<c 2>simple harmonic motion, a = – ω2xvelocity of particle in s.h.m., v = v 0 cos ωtv = ± ω √⎯ (x 02 – x 2)electric potential, V =Q 4πε0rcapacitors in series, 1/C = 1/C 1 + 1/C 2 + . . .capacitors in parallel, C = C 1 + C 2 + . . .energy of charged capacitor, W = QV resistors in series, R = R 1 + R 2 + . . .resistors in parallel, 1/R = 1/R 1 + 1/R 2 + . . .alternating current/voltage, x = x 0 sin ωt radioactive decay, x = x 0 exp(–λt )decay constant,λ =0.693t9702/41/M/J/10© UCLES 2010For Examiner’s UseSection AAnswer all the questions in the spaces provided.1 (a) Define the radian . (2)(b) A stone of weight 3.0 N is fixed, using glue, to one end P of a rigid rod CP , as shownin Fig. 1.1.NFig. 1.1The rod is rotated about end C so that the stone moves in a vertical circle of radius 85 cm.The angular speed ω of the rod and stone is gradually increased from zero until the gluesnaps. The glue fixing the stone snaps when the tension in it is 18 N.For the position of the stone at which the glue snaps, (i) on the dotted circle of Fig. 1.1, mark with the letter S the position of the stone, [1] (ii) calculate the angular speed ω of the stone.angular speed = ................................... rad s –1 [4]9702/41/M/J/10© UCLES 2010[Turn overForExaminer’s Use2 (a) Some gas, initially at a temperature of 27.2 °C, is heated so that its temperature risesto 38.8 °C.Calculate, in kelvin, to an appropriate number of decimal places, (i) the initial temperature of the gas,initial temperature = ............................................. K [2](ii) the rise in temperature.rise in temperature = ............................................ K [1](b) The pressure p of an ideal gas is given by the expressionp = 13ρϽc 2Ͼ where ρ is the density of the gas.(i) State the meaning of the symbol Ͻc 2Ͼ................................................................................................................................... (1)(ii) Use the expression to show that the mean kinetic energy <E K > of the atoms of anideal gas is given by the expression<E K > = 32kT .Explain any symbols that you use................................................................................................................................... .................................................................................................................................. .................................................................................................................................. .................................................................................................................................. .. (4)9702/41/M/J/10© UCLES 2010For Examiner’s Use(c) Helium-4 may be assumed to behave as an ideal gas. A cylinder has a constant volume of 7.8 × 103 cm 3 and contains helium-4 gas at apressure of 2.1 × 107 Pa and at a temperature of 290 K.Calculate, for the helium gas,(i) the amount of gas,amount = ......................................... mol [2](ii) the mean kinetic energy of the atoms,mean kinetic energy = .............................................. J [2](iii) the total internal energy.internal energy = .............................................. J [3]9702/41/M/J/10© UCLES 2010[Turn overFor Examiner’s Use3 (a) State what is meant by (i) oscillations ,.................................................................................................................................. (1)(ii) free oscillations,.................................................................................................................................. (1)(iii) simple harmonic motion ................................................................................................................................... .................................................................................................................................. (2)(b) Two inclined planes RA and LA each have the same constant gradient. They meet attheir lower edges, as shown in Fig. 3.1.Fig. 3.1A small ball moves from rest down plane RA and then rises up plane LA. It then moves down plane LA and rises up plane RA to its original height. The motion repeats itself.State and explain whether the motion of the ball is simple harmonic. (2)9702/41/M/J/10© UCLES 2010For Examiner’s Use4 (a) Explain what is meant by the potential energy of a body. (2)(b) Two deuterium (21H) nuclei each have initial kinetic energy E K and are initially separatedby a large distance.The nuclei may be considered to be spheres of diameter 3.8 × 10–15 m with their massesand charges concentrated at their centres.The nuclei move from their initial positions to their final position of just touching, asillustrated in Fig. 4.1.Hinitiallykinetic energy E K21H–15 mat rest finallykinetic energy E K21Fig. 4.1(i) For the two nuclei approaching each other, calculate the total change in1. gravitational potential energy,energy = ............................................ J [3]2. electric potential energy.energy = ............................................ J [3]9702/41/M/J/10© UCLES 2010[Turn overFor Examiner’s Use(ii) Use your answers in (i) to show that the initial kinetic energy E K of each nucleusis 0.19 MeV .[2](iii) The two nuclei may rebound from each other. Suggest one other effect that couldhappen to the two nuclei if the initial kinetic energy of each nucleus is greater than that calculated in (ii)................................................................................................................................... (1)9702/41/M/J/10© UCLES 2010For Examiner’s Use5 (a) A constant current is maintained in a long straight vertical wire. A Hall probe is positioneda distance rfrom the centre of the wire, as shown in Fig. 5.1.Fig. 5.1(i) Explain why, when the Hall probe is rotated about the horizontal axis XY , the Hallvoltage varies between a maximum positive value and a maximum negative value................................................................................................................................... .................................................................................................................................. (2)(ii) The maximum Hall voltage V H is measured at different distances r . Data for V H and the corresponding values of r are shown in Fig. 5.2.V H / V r / cm0.2900.1900.1400.0970.0730.0601.01.52.03.04.05.0Fig. 5.2It is thought that V H and r are related by an expression of the formV H = krwhere k is a constant.ForExaminer’sUse1. W ithout drawing a graph, use data from Fig. 5.2 to suggest whether theexpression is valid. [2]2. A graph showing the variation with 1rof V H is plotted. State the features of the graph that suggest that the expression is valid.........................................................................................................................................................................................................................................................[1] (b) The Hall probe in (a) is now replaced with a small coil of wire connected to a sensitivevoltmeter. The coil is arranged so that its plane is normal to the magnetic field of the wire.(i) State Faraday’s law of electromagnetic induction and hence explain why thevoltmeter indicates a zero reading....................................................................................................................................................................................................................................................................................................................................................................................................... (3)(ii) State three different ways in which an e.m.f. may be induced in the coil.1. ................................................................................................................................................................................................................................................................2. ................................................................................................................................................................................................................................................................3. .............................................................................................................................. (3)For Examiner’s Use6A student is asked to design a circuit by which a direct voltage of peak value 9.0 V is obtained from a 240 V alternating supply.The student uses a transformer that may be considered to be ideal and a bridge rectifier incorporating four ideal diodes.The partially completed circuit diagram is shown in Fig. 6.1.240 V loadFig. 6.1(a) On Fig. 6.1, draw symbols for the four diodes so as to produce the polarity across theload as shown on the diagram. [2] (b) Calculate the rationumber of turns on the secondary coil number of turns on the primary coil. ratio = (3)For Examiner’s Use7Negatively-charged particles are moving through a vacuum in a parallel beam. The particles have speed v . The particles enter a region of uniform magnetic field of flux density 930 μT. Initially, theparticles are travelling at right-angles to the magnetic field. The path of a single particle is shown in Fig. 7.1.uniform magnetic field,flux density 930 μTarc of radius 7.9 cmFig. 7.1The negatively-charged particles follow a curved path of radius 7.9 cm in the magnetic field. A uniform electric field is then applied in the same region as the magnetic field. For an electricfield strength of 12 kV m –1, the particles are undeviated as they pass through the region of the fields.(a) On Fig. 7.1, mark with an arrow the direction of the electric field. [1] (b) Calculate, for the negatively-charged particles,(i) the speed v ,v = ....................................... m s –1 [3](ii) the ratio charge mass .ratio = .................................... C kg –1 [3]For Examiner’s Use8A π0 meson is a sub-atomic particle.A stationary π0 meson, which has mass 2.4 × 10–28 kg, decays to form two γ-ray photons. The nuclear equation for this decay isπ0 γ + γ. (a) Explain why the two γ-ray photons have the same energy...........................................................................................................................................................................................................................................................................................................................................................................................................................[2] (b) Determine, for each γ-ray photon,(i) the energy, in joule,energy = .............................................. J [2](ii) the wavelength, wavelength = ............................................ m [2](iii) the momentum.ForExaminer’sUsemomentum = ........................................... N s [2]For Examiner’s UseSection BAnswer all the questions in the spaces provided.9 The circuit diagram of Fig. 9.1 is an amplifier circuit incorporating an operational amplifier(op-amp).1.5Fig. 9.1(a) (i) On Fig. 9.1, mark, with the letter X, the virtual earth.[1](ii) Explain what is meant by a virtual earth ....................................................................................................................................................................................................................................................................................................................................................................................................... (3)(b) In bright sunlight, the light-dependent resistor (LDR) has resistance 200 Ω.(i) Calculate, for the LDR in bright sunlight, the voltmeter reading. reading = ............................................ V [3]For Examiner’sUse (ii) The sunlight incident on the LDR becomes less bright. State and explain the effect on the voltmeter reading of this decrease in brightness....................................................................................................................................................................................................................................................................................................................................................................................................... (3)For Examiner’s Use 10 (a) Briefly explain the principles of CT scanning. (6)For Examiner’sUse(b)A simple section through a body consists of four voxels, as illustrated in Fig. 10.1.section directionsFig. 10.1An X-ray image of the section is obtained by viewing along each of the directions shown in Fig. 10.1. The detector readings for each direction of viewing are summed to give the pattern of readings shown in Fig. 10.2.25342231Fig. 10.2For any one direction, the total of the detector readings is 16.(i) For the pattern of readings of Fig. 10.2, state the magnitude of the backgroundreading.background reading = (1)(ii) On Fig. 10.1, mark the pattern of pixels for the four-voxel section.[2]For Examiner’s Use 11 Many radio stations now broadcast on FM rather than on AM. In general, FM is broadcast atmuch higher frequencies than AM.(a) Explain what is meant by FM (frequency modulation ).....................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................[2] (b) State two advantages and two disadvantages of FM transmissions when compared withAM transmissions.advantages of FM transmissions1. ...............................................................................................................................................................................................................................................................................2. ............................................................................................................................................................................................................................................................................... disadvantages of FM transmissions1. ...............................................................................................................................................................................................................................................................................2. ..................................................................................................................................... (4)Examiner’sUseCalculate the power of the signal received by the satellite.(a)power = .......................................... W [3](b)The signal received by the satellite is amplified and transmitted back to Earth.(i) Suggest a frequency for the signal that is sent back to Earth.frequency = ...................................... GHz [1] (ii) Give a reason for your answer in (i)................................................................................................................................... (1)Permission to reproduce items where third-party owned material protected by copyright is included has been sought and cleared where possible. Every reasonable effort has been made by the publisher (UCLES) to trace copyright holders, but if any items requiring clearance have unwittingly been included, the publisher will be pleased to make amends at the earliest possible opportunity.University of Cambridge International Examinations is part of the Cambridge Assessment Group. Cambridge Assessment is the brand name of University of Cambridge Local Examinations Syndicate (UCLES), which is itself a department of the University of Cambridge.。
量子纠缠 名言警句大全
量子纠缠名言警句大全1.在爱情中，量子纠缠就是一种永恒的连接。
2.量子纠缠让我们明白，世界的奇妙背后总有着无法想象的联系。
3.纠缠着的两颗量子，即使远隔千山万水，也能瞬间共鸣。
4.时间和空间在纠缠中失去了意义，唯有相互之间的联系是永恒。
5.量子纠缠是一种神秘而美妙的物理现象，让我们见识到宇宙的奥秘。
6.量子纠缠教会我们珍惜每一次相遇，因为那是命运赐予的美好瞬间。
7.纠缠的量子是宇宙中最美丽的情侣，它们的爱会穿越时空的隔阂。
8.量子纠缠让我们明白，即使分开了，心灵之间仍然紧密相连。
9.纠缠不是束缚，而是一种自由，连接着我们内心深处的渴望。
10.在量子纠缠的世界里，没有距离，只有爱与思念。
11.当我们感受到纠缠的存在，就会体会到宇宙的无限可能性。
12.每个人都是宇宙中的一颗量子，我们之间的纠缠让整个世界更加丰富多彩。
13.纠缠让我们相信，爱是唯一永恒的力量，无论经历多少变故。
14.量子纠缠是爱情、友情和亲情的精神象征，无声无息地影响着我们的生活。
15.无法捉摸的量子纠缠带给我们思考，这个世界的存在是如此神秘莫测。
16.纠缠的量子就像两颗心灵间的默契，永远共鸣在宇宙的旋律中。
17.无论多么微小的量子纠缠，都包含着宇宙最深刻的奥秘。
18.纠缠启示我们，真正的连接不在于言语，而是心灵的碰撞和共鸣。
19.在量子纠缠中，没有谁能离开谁，因为我们早已命中注定相逢。
20.量子纠缠是宇宙间最美好的礼物，让我们珍惜每一次奇妙的相遇。
21.“纠缠是量子力学的神秘现象，违背了我们传统的经典观念。
”22.“在纠缠中，两个或多个粒子之间的状态是紧密关联的，无论它们之间的距离有多远。
”23.“爱因斯坦称之为‘鬼魅距离作用’，这种情况下的粒子受到相互影响，无论它们之间有多远。
”24.“‘鬼魅距离作用’是一种超越经典物理学的概念，被认为是宇宙中最神秘的现象之一。
”25.“纠缠可以让我们窥视量子世界的精妙之处，展示了我们对自然界了解的局限性。
著名数学家弗里曼·戴森的演讲译文：鸟和青蛙
Freeman Dyson
ome mathematicians are birds, others are frogs. Birds fly high in the air and survey broad vistas of mathematics out to the far horizon. They delight in concepts that unify our thinking and bring together diverse problems from different parts of the landscape. Frogs live in the mud below and see only the flowers that grow nearby. They delight in the details of particular objects, and they solve problems one at a time. I happen to be a frog, but many of my best friends are birds. The main theme of my talk tonight is this. Mathematics needs both birds and frogs. Mathematics is rich and beautiful because birds give it broad visions and frogs give it intricate details. Mathematics is both great art and important science, because it combines generality of concepts with depth of structures. It is stupid to claim that birds are better than frogs because they see farther, or that frogs are better than birds because they see deeper. The world of mathematics is both broad and deep, and we need birds and frogs working together to explore it. This talk is called the Einstein lecture, and I am grateful to the American Mathematical Society for inviting me to do honor to Albert Einstein. Einstein was not a mathematician, but a physicist who had mixed feelings about mathematics. On the one hand, he had enormous respect for the power of mathematics to describe the workings of nature, and he had an instinct for mathematical beauty which led him onto the right track to find nature’s laws. On the other hand, he had no interest in pure mathematics, and he had no technical
自主移动机器人定位技术研究综述_张弦
·开发与创新·Overview of the Localization Technology of Autonomous Mobile RobotsZHANG Xian ，SU Zhi-Yuan（School of Automation ，Beijing Unversity of Post and Telecommunications ，Beijing 100876，China ）Abstract:Localization technology is one of the most basic and important function in autonomous mobile robot.This paper presents some technologies in the autonomous mobile robot localization,Focused on analyzing the technology based on landmark and probabilistic localization,analyses their advantages and limitations and indicates future research directions.Key words:autonomous mobile robot ；localizaiton ；landmark localization ；probabilistic localization机电产品开发与创新Development ＆Innovation of M achinery ＆E lectrical P roductsVol．23,No．2Mar ．,2010第23卷第2期2010年3月0引言自主导航移动机器人采用非固定路径移动的智能小车，由于具有更大的使用灵活性目前已成为目前机器人技术研究的一个热点。
常用物理英语词汇(全)
常用物理英语词汇(全)力学（Mechanics）1. Force（力）2. Acceleration（加速度）3. Momentum（动量）4. Kinetic Energy（动能）5. Potential Energy（势能）6. Gravity（重力）7. Friction（摩擦力）8. Torque（扭矩）9. Angular Momentum（角动量）10. Work（功）热学（Thermodynamics）11. Temperature（温度）12. Heat（热量）13. Internal Energy（内能）14. Entropy（熵）15. Boyle's Law（波义耳定律）16. Charles's Law（查理定律）17. GayLussac's Law（盖吕萨克定律）18. Ideal Gas Law（理想气体定律）19. First Law of Thermodynamics（热力学第一定律）20. Second Law of Thermodynamics（热力学第二定律）电磁学（Electromagnetism）21. Electric Charge（电荷）22. Electric Field（电场）23. Magnetic Field（磁场）24. Current（电流）25. Voltage（电压）26. Resistance（电阻）27. Capacitance（电容）28. Inductance（电感）29. Ohm's Law（欧姆定律）30. Ampère's Law（安培定律）光学（Optics）31. Light（光）32. Refraction（折射）33. Reflection（反射）34. Diffraction（衍射）35. Interference（干涉）36. Polarization（偏振）37. Lens（透镜）38. Prism（棱镜）39. Spectrum（光谱）40. Wave Optics（波动光学）现代物理（Modern Physics）41. Quantum Mechanics（量子力学）42. Relativity（相对论）43. Photon（光子）44. Electron（电子）45. Proton（质子）46. Neutron（中子）47. Quark（夸克）48. Black Hole（黑洞）49. Higgs Boson（希格斯玻色子）50. String Theory（弦理论）这些词汇仅为物理学中常用术语的一小部分。
Quantum Mechanics
Quantum MechanicsQuantum mechanics, also known as quantum physics, is a fundamental theory in physics that describes the behavior of matter and energy at the smallest scales—typically at the level of atoms and subatomic particles. It is a complex and intriguing field that has revolutionized our understanding of the universe, challenging our classical intuition and providing the foundation for many modern technologies. However, it also presents various conceptual and interpretational challenges that have sparked debates and discussions among physicists and philosophers. One of the central tenets of quantum mechanics is the principle of superposition, which states that particles can exist in multiple states simultaneously until they are measured or observed. This idea is famously illustrated by Schr?dinger's thought experiment involving a cat in a sealed box, which can be both alive and dead at the same time due to the uncertain state of a radioactive atom. While this concept has been supported by numerous experimental observations, it continues to defy our everyday experience and has led to profound philosophical questions about the nature of reality and the role of observation in shaping it. Another key aspect of quantum mechanics is the phenomenon of entanglement, where particles become interconnected in such a way that the state of one particle instantaneously influences the state of another, regardless of the distance between them. This "spooky action at a distance," as Einstein famously referred to it, has been experimentally verified and forms the basis of quantum technologies such as quantum cryptography and quantum computing. However, it challenges our classical notions of locality and raises questions about the nature of causality and the interconnectedness of the universe. The interpretation of quantum mechanics has been a subject of intense debate since its inception. The Copenhagen interpretation, proposed by Niels Bohr and Werner Heisenberg, asserts that the act of measurement collapses the wave function of a particle, determining its definite state. This view emphasizes the role of observation and measurement in defining reality, giving rise to the famous quote, "If you're not confused by quantum mechanics, you haven't really understood it." On the other hand, alternative interpretations such as the many-worlds interpretation and the pilot-wave theory offer different perspectives on the nature of quantum reality, leadingto ongoing discussions about the true nature of the quantum world. From a technological standpoint, quantum mechanics has led to groundbreaking advancements in areas such as computing, cryptography, and precision measurement. Quantum computers, which harness the principles of superposition and entanglement, havethe potential to solve complex problems exponentially faster than classical computers, offering transformative possibilities for fields such as drug discovery, materials science, and cryptography. Quantum cryptography leverages the principles of quantum mechanics to create secure communication channels that aretheoretically immune to eavesdropping, offering unprecedented levels of data security. Furthermore, quantum sensors and atomic clocks based on quantumprinciples have enabled unprecedented levels of precision in measurements, with applications ranging from GPS systems to gravitational wave detection. Despiteits remarkable successes, quantum mechanics continues to pose profound challenges and mysteries. The concept of wave-particle duality, where particles exhibit both wave-like and particle-like behavior, remains a fundamental enigma. The measurement problem, which addresses the nature of wave function collapse and the role of observation, continues to be a subject of philosophical and theoretical inquiry. Furthermore, the quest for a unified theory that reconciles quantum mechanics with general relativity, the other pillar of modern physics, remains a major unsolved problem in theoretical physics. In conclusion, quantum mechanics stands as one of the most profound and enigmatic theories in the history of science, reshaping our understanding of the fundamental nature of reality and opening up new frontiers in technology and philosophy. Its implications reach far beyond the realm of physics, challenging our intuitions and offering new ways of thinking about the nature of the universe. As we continue to explore and grapple with the intricacies of quantum mechanics, we are certain to encounter newinsights and challenges that will further deepen our appreciation of the quantum world.。
杨振宁的事迹英语作文
杨振宁的事迹英语作文Yang Zhenning, a renowned Chinese-American physicist, has left an indelible mark on the scientific community through his groundbreaking contributions and unwavering dedication to the pursuit of knowledge. Born in 1922 in Hefei, China, Yang's journey to becoming one of the most influential physicists of the 20th century was paved with remarkable achievements and a steadfast commitment to the advancement of science.Yang's early life was marked by a keen intellectual curiosity and a thirst for learning. He excelled academically, earning his bachelor's degree from the National Southwestern Associated University in 1942. Driven by his passion for physics, he continued his studies at the University of Chicago, where he obtained his Ph.D. in 1948 under the supervision of the renowned physicist Enrico Fermi.Upon completing his doctoral studies, Yang's career took a momentous turn when he collaborated with his colleague Tsung-Dao Lee on the groundbreaking research that would eventually lead to the discovery of the non-conservation of parity. This revolutionaryfinding, which challenged the long-held assumption of the symmetry of physical laws, earned Yang and Lee the Nobel Prize in Physics in 1957, making them the youngest recipients of the prestigious award at the time.The non-conservation of parity, as demonstrated by Yang and Lee, was a fundamental breakthrough in the field of particle physics. It shattered the prevailing belief that physical laws were invariant under the transformation of spatial coordinates, known as parity. Their work not only expanded our understanding of the fundamental forces governing the universe but also paved the way for further advancements in the field.Following this groundbreaking achievement, Yang continued to make significant contributions to various areas of physics. He made important contributions to the development of gauge theories, which unified the electromagnetic and weak nuclear forces, and played a crucial role in the formulation of the Standard Model of particle physics, a comprehensive framework that describes the fundamental particles and their interactions.Throughout his illustrious career, Yang has been recognized with numerous accolades and honors. In addition to the Nobel Prize, he has received the National Medal of Science, the Oppenheimer Prize, and the Dirac Medal, among other prestigious awards. His work hasbeen widely published in prestigious scientific journals, and he has been a respected figure in the global scientific community.Beyond his scientific achievements, Yang has also been a dedicated educator and mentor to generations of physicists. He has held prestigious academic positions at several renowned institutions, including the Institute for Advanced Study in Princeton, the University of Chicago, and the State University of New York at Stony Brook, where he served as the founding director of the Institute for Theoretical Physics.Yang's impact on the scientific community extends far beyond his own research and discoveries. He has been a tireless advocate for the advancement of science and the promotion of international scientific collaboration. Throughout his career, he has worked tirelessly to bridge the gap between the East and the West, fostering cultural exchange and promoting the exchange of ideas and knowledge.In recognition of his contributions to science and his efforts to promote global scientific cooperation, Yang has been honored with numerous international awards and accolades. He has received the Heineman Prize for Mathematical Physics, the Benjamin Franklin Medal, and the Niels Bohr International Gold Medal, among others.Despite his many accomplishments, Yang has remained humble anddedicated to the pursuit of scientific knowledge. He has inspired generations of physicists and scientists, who continue to build upon his groundbreaking work and strive to push the boundaries of our understanding of the natural world.As we reflect on the life and achievements of Yang Zhenning, we are reminded of the transformative power of scientific inquiry and the profound impact that a single individual can have on the course of human knowledge. Yang's legacy will continue to inspire and guide future generations of scientists, as they seek to unravel the mysteries of the universe and contribute to the advancement of our collective understanding of the natural world.。
Mass
so much is a mystery, even in the modern standard model of elementary particles. By contrast, until recently, neutrinos seemed to be massless, and in the 1950s physicists thought they had worked out why. The key is chirality. In biochemistry, chirality describes the ‘handedness’ of a molecule, which may look different from its mirror image. A simple molecule such as H2O looks the same as its mirror image, but a more complex molecule such as dextrose may not. That certain chiral molecules are important in biology, and their mirror-image molecules are not, is believed to reflect accidents in the evolution of life, rather than any inherent difference between the molecules. Neutrinos have a similar kind of chirality. Elementary particles have an intrinsic quantum-mechanical ‘spin’. Most particles can spin in a right-handed or left-handed sense around their direction of motion, but neutrinos always spin in a left-handed sense (Fig. 2). Like chirality in biology, this property may conceivably have its origins in a chance event, in this case an accident of the Big Bang. Such an intrinsic chirality is impossible for particles with mass (because the direction of spin of a massive particle can be changed by rotating the particle in its rest frame), so physicists concluded that neutrinos must have zero mass. But there is a problem with this argument, and it has to do with antimatter. Every particle of elementary matter has a corresponding antiparticle, with the same mass but opposite electric charge. For example, the antiparticle of the electron, e1 , is the positron, denoted e& . Similarly, the neutrino has an antiparticle: the antineutrino. The antineutrino has the opposite chirality to the neutrino — it always spins in a right-handed sense around its direction of motion (Fig. 2). Apart from their chirality, how can you tell a neutrino from an antineutrino? They are both electrically neutral, so we cannot
有关量子力学的英语作文
有关量子力学的英语作文Quantum Mechanics: The Mysterious World of Particles。
Quantum mechanics is a branch of physics that studies the behavior of particles on a microscopic level. It is a theory that explains the nature of matter and energy at the smallest scale, where classical physics fails to provide an accurate description. The principles of quantum mechanics have revolutionized our understanding of the universe, and have led to the development of many technological advancements.One of the most fundamental principles of quantum mechanics is the wave-particle duality. This principlestates that particles can exhibit both wave-like andparticle-like behavior, depending on the experimental setup. For example, electrons can behave like particles when they are detected by a screen, but like waves when they pass through a double-slit experiment. This duality is not intuitive, and it challenges our classical understanding ofphysics.Another important principle of quantum mechanics is superposition. This principle states that particles can exist in multiple states at the same time until they are observed or measured. For example, an electron can exist in multiple energy states simultaneously until it is measured, and then it collapses into a single state. This concept is central to the idea of quantum computing, which promises to revolutionize computing technology by exploiting the power of superposition and entanglement.Entanglement is another fascinating concept of quantum mechanics. It refers to the phenomenon where two particles can become correlated in such a way that their states are dependent on each other, even when they are separated by vast distances. This concept has been demonstrated in experiments, and it has led to the development of quantum teleportation, which allows the transfer of quantum information between two entangled particles.The principles of quantum mechanics have led to manytechnological advancements, such as transistors, lasers, and MRI machines. Quantum mechanics has also led to the development of new materials, such as superconductors, which have zero resistance to electrical current. Furthermore, quantum mechanics has the potential to revolutionize cryptography, by enabling the creation of unbreakable codes using the principles of entanglement.In conclusion, quantum mechanics is a fascinating and mysterious world that challenges our classical understanding of physics. Its principles have revolutionized our understanding of the universe, and have led to the development of many technological advancements. As we continue to explore the world of quantum mechanics, we are sure to discover new and exciting phenomena that will change our understanding of the universe.。
有关物理的英语作文
有关物理的英语作文Title: Exploring the Wonders of Physics。
Physics is a captivating realm of science that delves into the fundamental principles governing the universe. From the tiniest particles to the vast expanses of space, physics encompasses a broad spectrum of phenomena thatshape our understanding of the world. In this essay, wewill embark on a journey to explore the wonders of physics, delving into its key concepts and their implications.One of the cornerstone principles of physics isNewton's laws of motion. These laws describe the behaviorof objects in motion and have profound implications for fields ranging from engineering to astronomy. The first law, often referred to as the law of inertia, states that an object will remain at rest or in uniform motion unlessacted upon by an external force. This law forms the basisfor our understanding of inertia and the conservation of momentum, crucial concepts in fields like mechanicalengineering and transportation.The second law of motion, often expressed as F = ma, quantifies the relationship between force, mass, and acceleration. This law allows us to predict how objectswill move when subjected to various forces, laying the groundwork for the development of technologies such as automobiles and rockets. The third law, stating that for every action, there is an equal and opposite reaction, underpins our understanding of forces in nature, from the propulsion of spacecraft to the mechanics of sports like swimming and rowing.Another fundamental concept in physics is the theory of relativity, developed by Albert Einstein in the early 20th century. This theory revolutionized our understanding of space, time, and gravity, introducing the concept of spacetime as a unified fabric woven by mass and energy. Special relativity, which deals with the behavior of objects moving at high speeds, led to groundbreaking insights into phenomena such as time dilation and length contraction, challenging our intuitive notions of time andspace.General relativity, on the other hand, describes the force of gravity as the curvature of spacetime caused by mass and energy. This theory has been confirmed through observations of phenomena such as gravitational lensing and the precession of Mercury's orbit, cementing its status as one of the most successful theories in physics. General relativity has also paved the way for technologies such as global positioning systems (GPS), which rely on precise measurements of time dilation to function accurately.Quantum mechanics represents another fascinating frontier in physics, dealing with the behavior of particles at the smallest scales. This branch of physics has led to profound insights into the nature of reality, challenging classical notions of determinism and causality. Quantum mechanics predicts phenomena such as wave-particle duality, where particles exhibit both particle-like and wave-like behavior, and entanglement, where particles become interconnected regardless of distance.The applications of quantum mechanics are far-reaching, with implications for fields such as computing, cryptography, and materials science. Quantum computers, for example, harness the principles of superposition and entanglement to perform complex calculations at speeds far beyond classical computers, promising revolutionary advances in areas like drug discovery and optimization problems.In addition to these foundational principles, physics continues to push the boundaries of our understanding through cutting-edge research in fields such as astrophysics, particle physics, and cosmology. From the discovery of exoplanets orbiting distant stars to the search for elusive dark matter particles, physicists are constantly uncovering new mysteries of the universe and refining our understanding of its underlying laws.In conclusion, physics is a vast and diverse field that encompasses everything from the motion of celestial bodies to the behavior of subatomic particles. Through its foundational principles and groundbreaking discoveries,physics provides us with a deeper understanding of the world around us and opens doors to new technologies and possibilities. As we continue to explore the wonders of physics, we embark on a journey of discovery that promises to expand our horizons and shape the future of humanity.。
翻译
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Cosmic
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Our idea is to consider just this theory ( 4) without the Higgs potential (VHiggs (j j) = 0) but in the presence of the Einstein gravity theory with a conformally coupled scalar eld
On the Cosmological Origin of the Homogeneous Scalar Field in Uni ed Theories
V.N.Pervushin, V.I Smirichinski
Joint Institute for Nuclear Research, 141980, Dubna, Russia.
LG (g; A0 ; j o
To nd minimum of the action with the Lagrangian (5), we express it in terms of the conformal invariant variables, marked by (c), extracting the space-scale factor 6] 1
? cr + 0 +
(14)
The geometrical observables of the Friedmann Universe, in comoving frame of reference, are constructed by using the inverse conformal transformation (7) of the dynamical variables and coordinates, including the Friedmann time interval dtF = a0 d and distance DF = a0 Dc 6, 7]. 2
凯米拉钛白粉说明书
Sachtleben TiO2 has these requirements covered. Sachtleben has an excellent reputation in the white pigment market and is one of the global market leader in TiO2 pigments for packaging inks.
White ink is stored in sealed containers prior to printing and no settling of the pigment is allowed, even at low viscosity. Sachtleben TiO2 grades are stable in different flexible packaging ink formulations and they are inert to most chemicals used in inks.
Good dispersibility is a distinct advantage, as it has a great influence on the production costs and on postdispersion. The maximum particle size allowed in inks, especially in flexo and gravure inks, is ideally below 2 µm. The surface treatments of Sachtleben TiO2 grades are developed to guarantee the best dispersion. This is the foundation for trouble-free printing.
弱相互作用表示
弱相互作用表示The weak interaction, also known as the weak force or weak nuclear force, is one of the four fundamental forces in nature. It is responsible for the phenomenon of beta decay in nuclear physics, where a neutron decays into a proton, an electron, and an antineutrino. The weak force is the force that allows particles to change into different types of particles, a process known as particle decay.弱相互作用是自然界四种基本力之一，也被称为弱力或弱核力。
在核物理学中，它负责贝塔衰变现象，即中子衰变为质子、电子和反中微子。
弱力是一种使粒子转变为不同类型粒子的力量，这一过程被称为粒子衰变。
The weak force is mediated by the W and Z bosons, which are massive particles that carry the weak nuclear force. These bosons are responsible for transmitting the weak force between particles and are essential for understanding the behavior of subatomic particles. The discovery of the W and Z bosons in 1983 confirmed the existence of the weak force and provided further evidence for the Standard Model of particle physics.弱力由W和Z玻色子传递，它们是携带弱核力的大质量粒子。
GPU 在SPH 方法模拟溃坝问题的应用研究
ＣＵＤＡ 线程是设备端运行的基本单位。 线程是 以 Ｇｒｉｄ、 Ｂｌｏｃｋ、 Ｔｈｒｅａｄ 为 层 次 机 构 执 行 的。 每 个 Ｂｌｏｃｋ 由若干个 Ｔｈｒｅａｄ 组成一维、二维或者三维形 式，而每个 Ｇｒｉｄ 则由若干个 Ｂｌｏｃｋ 组成一维、二维或 者三维形式。 在设备端执行的过程中，线程作为最 小执行形式被分派到 Ｂｌｏｃｋ 中，而 Ｂｌｏｃｋ 又被分派到 Ｇｒｉｄ 中，控制器将 Ｂｌｏｃｋ 发送到流多处理器中，进而 将线程发送到流处理器中计算相应指令，执行结束
（２）
经离散 化 后 Ｎ⁃Ｓ 方 程 质 量 守 恒， 动 量 守 恒 的
ＳＰＨ 表达式可写为
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本文选取 Ｍｏｎａｇｈａｎ［１３］ 提出的三次样条函数作
第 ６ 期 杨志国，等：ＧＰＵ 在 ＳＰＨ 方法模拟溃坝问题的应用研究
·６６３·
后完成设备端计算任务，返回主机端。 ２．３ ＳＰＨ 并行模式
本文在 ＳＰＨ 方法的每步迭代过程中，以单线程 控制单个流场粒子，以多线程同时执行的方式计算 不同粒子的相应流场物理量。 线程数量的多少取决 于 ＧＰＵ 硬件的配置，而并行效率则与线程数量和 ＧＰＵ 计算能力有很大的关系。
网络出版时间：２０１４⁃０５⁃１４ １５：４９：４１．
细颗粒物 PM2.5 的简介-英语版
Fine Particulate Matter PM2.5: A Brief IntroductionIn the urban air quality daily or weekly report, respirable and total suspended particulate matter are two kinds of air pollutants which are familiar to people. Respirable particulate matter also called PM10, of which the diameter is greater than 2.5 microns, equal to or less than 10 microns, and can enter human respiratory systems; and total suspended particulate, also known as PM100, is a particle of less than or equal to 100 microns in diameter. PM2.5 with a diameter less than or equal to 2.5 microns which is less than 1/20 of a person's hair in the atmosphere known as a kind of particulate matter which can enters one’s lung. The full name of PM in English is particulate matter.Although PM2.5 is a component of the earth's atmosphere only with a very small quantity, it has an important influence on air quality and visibility. Compared with coarser atmospheric particles, PM2.5 is in a small size, and rich of a lot of toxic and harmful substances which has long residence time and conveying distance in the atmosphere, thus it makes a bigger impact on human health and environmental quality of the atmosphere. The higher the quantity, the more serious the air pollution is. 1. Particle SourceDaily power generation, industrial production, automobile exhaust emissions and other processes related to burning of residues are the main source of PM2.5, which mostly contain heavy metals and other toxic substances.In general, the coarse particulate matter with a diameter of 2.5 microns to 10 microns is mainly from the road dust; PM2.5 is mainly generated by fossil fuel combustion (such as motor vehicle exhaust, coal), and volatile organic compounds.2. Physical DamageMeteorological and medical experts believe that the haze caused by fine particles are even more harmful to human health than sandstorms. Particles with a size of 10 microns or more, will be blocked in the outside of the person's nose; Particulates, diameter between 2.5 and 10 microns, can enter the upper respiratory tract, and part of which will be excreted with the sputum together and held by the villi inside of the nose. Particulates inhaled will penetrate the bronchus, disturbance the gas exchange in the lungs causing diseases such as asthma, bronchitis and cardiovascular and so on. On average, each person will inhale about 10 thousand liters of air, and particulates in the alveolar can be absorbed quickly and directly penetrate into the blood anddistributed all around the body by circulation without the liver detoxication process. It may has serious consequences on those patients with anemia and blood circulation disorders, such as aggravating respiratory disease, caucusing heart diseases like congestive heart failure and coronary artery disease.In short, these particulates can also enter into the blood through the bronchial and alveolar, and among which harmful gases, heavy metals dissolved in the blood are even more harmful to human health. The physiological structure of the human body determines the lack of ability of filtering and blocking PM2.5, while its harm to human health is gradually exposed to us with the progress of medical technology.In EU countries, PM2.5 led to a 8.6 month average decrease in life expectancy. PM2.5 can also be a carrier of viruses and bacteria, promoting the spread of respiratory infections. Now PM2.5 is be listed in the air quality standards by the main developed countries and Japan, Thailand, India. PM2.5 has not been included in China's environmental air quality indicators, thus this is the root cause of the conflict between the U. S. embassy and the official of the government on the data.3 Monitoring SituationThe standard about PM2.5, proposed by the United States in 1997, is mainly for more effective monitoring of small particles which are harmful to humans and appear with increasing industrialization and be omitted in the old standard.By the end of 2010, in addition to the United States and the European Union some countries with PM2.5 listed in the national standard and mandatory restrictions, most countries in the world have not yet carried out the monitoring of the PM2.5, but on the PM10 monitoring.4. Current Situation of ChinaAccording to the evaluation report of urban air quality information disclosure index (AQTI) by Law School in Renmin University of China and Public Environment Research Center (IPE) released in January 2011, Beijing, Shanghai, Guangzhou, Chongqing and other 20 domestic cities generally did not carry out the supervision of fine particles.It worth noting that cities such as London, Paris, New York with frequently and closely supervision on PM2.5, their pollution level is relatively low. At the same time, large cities in the many developing countries such as Mexico City and New Delhi and other cities, also had to carry out the frequently and closely supervision on PM2.5. Beginning in January 1, 2011, the Ministry of environmental protection issued the"Ambient Air PM10 and PM2.5 Weight Determination Method". "Determination" for the first time makes the standard of PM2.5. But in the recently revising of the "ambient air quality standards" by the environmental protection department, PM2.5 is not been included in the mandatory monitoring indicators.On November 10th, 2011, in the seventh regional air quality management international seminar, Vice Minister of environmental protection Zhang Lijun said China's PM2.5 atmospheric environmental quality standards will soon be introduced. Standards will use the data specified in the first transition period by the WHO (WHO) to illustrate the PM2.5 index of pollution hazards.On November 15th, 2011, the famous atmospheric environment experts, Dean of the school of environmental science and engineering of Peking University, Zhang Yuanhang revealed that the World Health Organization has a more loosening standard compared with United States. Even according to the WHO standards, after joining PM2.5, cities meet the air quality standards will fall from 80% now to 20%. “I think this is reason that the Ministry of environmental protection has been unable to determine to list the PM2.5 into the air quality monitoring system”.On December 5th, 2011, deadline of the "Ambient Air Quality Standard" (second draft) to solicit public comment, new standard intends to fully implement in 2016. Beijing, Tianjin, the Yangtze River Delta, the Pearl River Delta region and nine city clusters may be forced to monitor PM2.5 and release data in advance.5. Governance PolicyFor air pollution and climate change, it is necessary to adopt a unified rather than separate coping strategy. Due to there is a common cause of air pollution and climate change to a large extent - mainly caused by the fossil fuel combustion emissions, thus reducing and controlling air pollution should be consistent with reducing greenhouse gas emissions in action.Some studies have pointed out that the increase in atmospheric aerosols reduces the amount of solar radiation reaching the ground, which is contrary to the warming effect of greenhouse gases. 50% of the surface warming caused by greenhouse gases may be offset by the cooling effect of aerosols. Once the removal of aerosols will make the greenhouse gas temperature increases more significantly, which will further increase the pressure on CO2 emission reduction. Air quality and climate change cannot be solved in isolation, they are closely coupled together.A more complex model of earth system and a long term monitoring system forclimate and biogeochemical variables must be developed. This complex earth system model can be used to simulate and predict the important physical, chemical and biological processes and feedback mechanisms in the above two areas, which is a major challenge.If an attempt is made to maintain global warming at a prescribed threshold, it is necessary not only to consider carbon dioxide emissions, but also to consider measures to improve air quality and the consequences of climate change. In order to economically reach the greatest savings and a win-win effect, emissions reducing measure and low carbon strategy for air pollution and climate change should be taken cooperatively. In other words, it should adopt a uniform and not separate scientific research and strategy. Especially, in the future, with the air pollution being continuously controlled and improved, it can greatly reduce the cooling effects of aerosols, which will further increase the future greenhouse gas emission reductions, otherwise global temperatures will increase with a faster speed and quantity. For developing countries like China with rapid economic development, the strategy is particularly important. Because these two problems not only exist at the same time, but also, both rapid grow with the economic growth and energy consumption, leading to serious air pollution and increasing greenhouse gas emissions.In the energy structure and industrial structure adjustment, comprehensive or integrated technology of greenhouse gas and aerosol emissions should be considered in together, making the emissions be reduced and controlled; all forces should be organized to write the first relatively complete list of China's aerosol emission; Further improvement of the greenhouse gas and aerosol observation network should be make, especially the network expanding and encryption of the Aerosol Observation; To provide scientific basis and support for the forecasts of China's medium and long term air pollution and its environment and climate impacts, study on the interaction of aerosol-cloud-climate change with air pollution and climate change should be taken, and the mutual coupling and nested set model system of air pollution mode of climate model (global and regional mode) and should be developed; a risk assessment system for coupled air pollution and climate change should be established, based on the interaction and future scenario prediction, which can provide consequences and severity assessment for the social and economic sectors.。
欧洲药典7.5版
INDEX
To aid users the index includes a reference to the supplement in which the latest version of a text can be found. For example : Amikacin sulfate...............................................7.5-4579 means the monograph Amikacin sulfate can be found on page 4579 of Supplement 7.5. Note that where no reference to a supplement is made, the text can be found in the principal volume.
English index ........................................................................ 4707
Latin index ................................................................................. 4739
EUROPEAN PHARMACOPபைடு நூலகம்EIA 7.5
Index
Numerics 1. General notices ................................................................... 7.5-4453 2.1.1. Droppers...................
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mn = k − n m p
where k is a constant and m P = (hc / G )1 / 2 is the Planck Mass.
(1)
2
First, the value of k in (1) is determined, from which values of n are deduced for the quarks. Non-integer values of n are then presented for the hadrons of zero orbital angular momentum in the JP=1/2+ light baryon octet, the JP=3/2+ light baryon decuplet, the pseudoscalar and vector light meson nonets, for charmed and bottom hadrons of zero orbital angular momentum and for charmonium and bottomium states. Building on the values of quark mass generated by the analysis, hadron mass construction equations are formulated. Finally, particle mass partnerships are identified. All mass measurements referred to in this paper have been taken from the Particle Data Group’s listings, 2002 [13]. The views expressed in this paper are those of the author and not necessarily those of NNC Ltd. 2 The Particle Mass Equation
To determine the value of k in (1), relationships were sought between the quark masses. The Particle Data Group evaluate a range of mass values for each quark, so it was necessary to extract from the ranges a single value of mass for each quark. The mid-range values were taken. The data are presented in Table 1. Table 1 Quark mass evaluations of the Particle Data Group, 2002 [13] Quark up (u) down (d) strange (s) charm (c) bottom (b) top (t) Mass evaluation range 1.5 - 4.5 MeV 5.0 - 8.5 MeV 80 - 155 MeV 1.0 - 1.4 GeV 4.0 - 4.5 GeV 174.3 ± 5.1 GeV Mid-range value 3 MeV 6.75 MeV 117.5 MeV 1.2 GeV 4.25 GeV 174.3 GeV
1
1
Introduction
In the Standard Model of particle physics [1], the Higgs mechanism of spontaneous electro-weak symmetry breaking gives the particles their masses. Precision electroweak measurements [2] suggest that the mass of the Higgs boson is less than a few hundred GeV. But because quantum corrections to the Higgs mass are quadratically divergent in the Standard Model, the Higgs boson can receive a very large radiative mass correction from a higher mass scale, which is inconsistent with the requirement that its mass should be relatively low. This is the ‘hierarchy problem’ of particle physics, equivalent to explaining the immense gulf in mass between the electro-weak scale (~103 GeV) and the GUT scale of ~1016 GeV or the Planck scale of ~1019 GeV. Various approaches have been developed to resolve the hierarchy problem. Among these are supersymmetry [3], technicolour theories [4] and extra-dimensional theories [5-10]. Whatever the solution turns out to be, it should eventually be incorporated into an all-encompassing theory that includes gravity and reconciles it with quantum mechanics [11]. The unification mass of the all-encompassing theory would be of the order of the Planck scale, the natural scale of string theory. According to string theory, the properties of an elementary particle, including its mass, are determined by the resonant pattern of vibration that its internal string executes [12]. The energy of the vibrating string is largely cancelled by quantum mechanical effects to produce the comparatively minute masses of the particles identified to date. The unified model has been built upon the premise that particle masses are related directly to the Planck Mass. The quarks of the Standard Model are conjectured to be the elementary units of the model, occupying levels within a mass spectrum that descends from the Planck Mass in a geometric progression. The mass of the nth level is given by
A unified model of particle mass
Bernard F. Riley NNC Ltd., Birchwood Park, Warrington WA3 6BZ, United Kingdom. bernard.riley@
Abstract The quark masses evaluated by the Particle Data Group are consistent with terms in a geometric progression of mass values descending from the Planck Mass. The common ratio of the sequence is 2/π. The quarks occupy the ‘principal’ levels of the mass spectrum, characterised by a new quantum number, n. Hadrons occupy mass sub-levels, characterised by fractional values of n. The quark masses of the model are used to formulate hadron mass construction equations based on the masses of neutral precursor particles. Hadron mass partnerships occur, in which mass differences arising from differences in spin, isospin and isospin projection are equal to the masses of principal levels. Mass partnerships also occur between the charged leptons and pseudoscalar mesons.