bluuebunny/crossref_metadata_2025 huggingface dataset:
Underground nesting in the megapodes
Authors: Booth D T , Jones D N
Published: November 2023

The Family Megapodiidae is distributed throughout the islands of the Indo Australian region east of Wallace’s Line including New Guinea, Australia and the Philippines, as well as on numerous islands in the southern Pacific as far east as Tonga (Joneset al. 1995). Megapodes appear never to have been present on the mainland or larger islands of south-east Asia (such as Java, Sumatra and most of Borneo) but are present on the Nicobar and Andaman Islands in the Bay of Bengal (see Dekker 1989). At present 22 species are recognised (Joneset al. 1995). Recent paleontological data suggests, however, that an additional 23-33 species were exterminated soon after the arrival of humans in the island chains of southern Oceania over the last few millennia (Steadman 1999).
Statistical Mechanics
Authors: Wark J S , Glazer A M
Published: November 2023

Statistical mechanics is the science of predicting the observable properties of a multiple bodied system by studying the statistics of the behaviour of its individual constituents, whether they are atoms, molecules, photons, etc. It provides the link between macroscopic and microscopic states, and as such has the potential to be one of the most satisfying parts of an undergraduate science course - linking in an elegant manner the quantum world with everyday observations of systems containing large numbers of particles. This excellent text is designed to introduce the fundamentals of the subject of statistical mechanics at a level suitable for students who meet the subject for the first time. The treatment given here is designed to give the student a feeling for the topic of statistical mechanics without being held back by the need to understand complex mathematics. The text is concise and concentrates on the understanding of fundamental aspects. Numerous questions with worked solutions are given throughout.
Photons and Phonons
Authors: Wark J S , Glazer A M
Published: November 2023

Having discussed the statistical mechanics of a gas of fermions, let us now turn our attention to bosons. Recall that bosons are integer-spin particles which have symmetric wave functions upon exchange, and there is no restriction on the number occupying the same state.
The End is in Sight
Authors: Wark J S , Glazer A M
Published: November 2023

You can see that we are now integrating over a 6-dimensional space whose axes are Px,Py,Pz, x, y, z. This space is referred to as ‘phase space’. In order to describe the particle we need to specify six coordinates, three for momentum, and three for position in our 6-dimensional phase space.
Freshwater-Swamp Forests
Authors: Whitten Tony , Damanik Sengli J , Anwar Janzanul , Hisyam Nazaruddin
Published: November 2023

Freshwater-swamp forest and related vegetation grow on soils where there is occasional inundation of mineral-1ich fresh water of pH 6 and above and where the water level fluctuates so that periodic drying of the soil surface occurs. The floods may originate from rain or from river water backing up in response to high tides. The major physical differences between this and peatswamp forest are the lack of deep peat (a few centimetres thickness is sometimes found but this seems to have little effect on tree species composition), and the sources of water being rivers and rain water (Whitmore 1984). Although freshwater-swamp forest normally forms on riverine alluvium, it can also be expected, under natural conditions, to form on alluvium deposited by larger lakes where wave action prevents the formation of peat, such as in ‘Lake’ Bento, Kerinci.
The Use of Cooling Deactivation to Reveal the Neural Bases of Lesion-induced Plasticity in the Developing and Mature Cerebral Cortex
Authors: Payne Bertram R , Lomber Stephen G
Published: November 2023

Cerebral lesions often produce specific deficits in neural performance and behavior. However, they are also characterized by a subsequent attenuation in the severity of the deficits. According to Kolb and Whishaw (1995) factors described as contributing to recovery of function include regeneration of connections to the area that was previously innervated, sprouting of fibers to innervate new targets structures, denervation supersensitivity to application of the same stimulus, disinhibition of potential compensatory zones and the activation of so-called “silent synapses.” Moreover, functional recovery is more likely for complex behaviors that are composed of many components, and it is more pronounced after incomplete lesions. However, recovery is severely limited for neural functions that are highly localized. For example, a lesion of primary motor cortex induces paralysis of voluntary movement and a lesion of primary visual cortex abolishes conscious vision.
Anthropological Perspectives on the Study of Ancient Disease
Authors: Ubelaker Douglas H
Published: November 2023

Recent concern about emerging infectious diseases that threaten human populations has focused new attention on the complex factors involved. Fischer and Klose’s (1996) edited volume on infectious dis eases stresses the importance of historical perspective in the understanding of disease emergence. Within that volume, Wilson (1996) describes factors that can be involved in the disease process such as migration, environmental shifts, changes in land use, socioeconomic factors, technological aspects, medical treatment, demographic factors, population vulnerability, formation of new habitats, and microbial evolution. These factors are not only key to our understanding of the emergence of new diseases in contemporary populations, but also to the past human disease experience. Our interpretations of past human disease depend not only on research capable of identifing the organisms involved but also our understanding of conditions such as those that contribute to the emergence and human impact of disease.
The function χ, entropies, and representation of nonlinear functions
Authors: Perthame Benoît
Published: November 2023

In this chapter we consider a general problem. Let the sequence (u  n(x))n∈ℕ be bounded in L ∞(ℝd ). After extraction of a subsequence, we may always assume that it converges in L∞ − w* to a function u∊ L∞(ℝd ). Consider now smooth functions S ℝ → ℝ. In general it is impossible to represent the weak limit of the family S(u  n) in terms of u only (see the example in Section 2.4). Such a description, for all functions S, cannot be achieved by a function of the single variable x ∊ ℝd and a higher-dimensional object is needed. Here, we present a simple method to describe these limits. It makes use of a particular indicator function, called the χ function, which will be used in a fundamental way for the kinetic formulation of scalar conservation laws in later chapters and which is a (d + 1)-dimensional object. The presentation below is an alternative approach to the so-called Young measures which are closely related objects.
Free electron lasers (FELs)
Authors: Margaritondo Giorgio
Published: November 2023

Synchrotron sources emit radiation with properties similar to lasers—for example, the undulators produce collimated, monochromatic and (partly) coherent light. On the other hand, the working principles of synchrotrons are different from those of lasers.
Ana Lysis Of Microstructure
Authors: Bhattacharya Kaushik
Published: November 2023

We understood why martensitic materials form microstructure in Chapter 6 and we studied some interesting examples in Chapter 7. In the process, we developed a description of microstructure and a method for constructing it. Using these, we can construct as many different examples as we wish. However, this constructive method is inherently limited.
Geometrical Ly Linear Theory
Authors: Bhattacharya Kaushik
Published: November 2023

The theory we have discussed so far is difficult for two inherent reasons. The first is the properties of the material itself. The phase transformation leads to a multi-well energy and thus the behaviour of the material is physically extremely non- linear. The second is geometry. When we compose two deformations, i.e., perform one deformation following another, we have to multiply the deformation gradients instead of adding them. A simple example of this is rigid rotations.
Supersymmetry: Theory, Experiment, and Cosmology
Authors: Binétruy P
Published: November 2023

This book describes the basic concepts of supersymmetric theories. It is aimed at theorists, experimentalists and cosmologists interested in supersymmetry, and its content is correspondingly divided into three distinct tracks of study. The topics covered include a discussion of the motivation for supersymmetry in fundamental physics, a description of the minimal supersymmetric model as well as models of grand unification and string models, a presentation of the main scenarios for supersymmetry breaking, including the concepts and results of dynamical breaking. On the astrophysics/cosmology side, the book includes discussions of supersymmetric dark matter candidates, inflation, dark energy, and the cosmological constant problem. Some very basic knowledge of quantum field theory is needed and extensive appendices (in particular an introduction to the Standard Model of fundamental interactions) allow the reader to refresh and complete their notions.
Transporting UCN
Authors: Ignatovich V K , Pontecorvo G B
Published: November 2023

This chapter deals in the main with neutron guides, and only at the very end will the issue be touched upon of honeutrons are transported in a sealed vessel. Neutron guides serve to extract the neutrons from the reactor core to the experimental hall, beyond the biological shield, and to separate low-energy neutrons from the direct beam. The intensity of the UCN themselves, however, is then attenuated. Obviously the attenuation is more significant when the walls of the neutron guide are rougher and more contaminated by hydrogen and when the vacuum inside it is poor. As far as the vacuum is concerned, operating experience is in quite good agreement with theoretical expectations and reveals that, at pressures lower than 10−3 mm Hg, residual gases actually do not hinder the passage of the UCN. Nevertheless, the vacuum is quite controllable. The contamination of the walls, however, and the degree of roughness are much more difficult to control.
Magnetism in Disorder
Authors: Hicks Trevor J
Published: November 2023

This book addresses aspects of neutron scattering associated with magnetic systems in disorder. These systems range in complexity from an isolated defect in a ferromagnet to materials such as amorphous spin glass materials which have massive disorder in terms of both atomic arrangement and magnetism. The primary focus of the text is neutron scattering but the author draws a connection with other probes of magnetic systems whenever appropriate. Topics covered include: the relationship between the neutron cross section and the magnetization and susceptibility of magnetic materials; polarized neutron techniques; and properties of dilute ferromagnetic alloys, spin glasses, and amorphous magnets.
Theoretical foundation
Authors: Schülke Winfried
Published: November 2023

At many points in this book, we have referred to basic relations in order to interpret certain aspects of inelastic X-ray scattering experiments, without deriving the corresponding equations by starting from basic principles. We have chosen this way of presenting the evidences drawn from inelastic scattering experiments because otherwise the reader might be too much discouraged by the necessary mathematical formalism. On the other hand, a more theoretically interested reader, of course, will have missed a unifying concept that binds together all the different branches of the field. Therefore, it is the aim of this chapter to add such a theoretical foundation as a supplement.
Motor co-ordination
Authors: Holland Owen , McFarland David
Published: November 2023

The nervous system is responsible for controlling behaviour and, to a certain extent, for controlling the animal’s internal environment. This control is exercised by commands to muscles and glands. Muscles are made up of complex protein molecules that are capable of contraction and relaxation. Nerve endings connect with muscles by means of synapses similar to those by which neurones connect with each other. The nerve impulses arriving at the neuromuscular junction set up electrical potentials, which cause the muscle to contract. Muscular relaxation results from lack of stimulation. When the muscle contracts it becomes shorter, provided it is not prevented from doing so by being fixed at each end. A muscle can lengthen
Additional Topics in Mechanics
Authors: Wasserman Robert H
Published: November 2023

We will continue to compare the Hamiltonian and Lagrangian formulations of mechanics, and get particular results when we think of configuration space as a pseudo-Riemannian manifold. We will then touch on the important ideas of momentum mappings and conservation laws, and finally on the Hamilton-Jacobi theory for solving the Hamilton canonical equations.
Einstein Spacetimes
Authors: Wasserman Robert H
Published: November 2023

In this chapter, we will construct Einstein’s cosmological models as represented by his field equations, eqs. (22.17) and (22.27). We will include some motivation and justification for these models and one interesting general consequence.
A little more about the physics of quasicrystals
Authors: Janot C
Published: November 2023

Quasicrystals pose a fundamental challenge to our understanding of the physical properties of condensed matter. As we have repeatedly stated, they lack the translational periodic order present in classical crystals. But they lack also the randomness present in truly disordered systems. They have, however, perfectly ordered structures that should generate proper selection rules for the formulation of their physical behaviour. Apparently, no one has so far succeeded in using this order, even within model descriptions such as the Penrose tiling scheme.
Statistical mechanics
Authors: Binney J J , Dowrick N J , Fisher A J , Newman M E J
Published: November 2023

Statistical mechanics is the art of predicting the behaviour of a system with a large number of degrees of freedom, given the laws governing its microscopic behaviour. It divides naturally into two parts. The first is the more fundamental. It tries to answer general questions concerning the behaviour of systems with many degrees of freedom, such as how order can arise from the apparent chaos of the microscopic behaviour, and how time-symmetric microscopic laws can give rise to the time asymmetry observed in the macroscopic world. The second part of statistical mechanics is concerned with using the results of this analysis to determine the behaviour of specific systems. This is what we will be doing in this book. Statistical mechanics will be used as a tool to study critical phenomena in particular systems.
Mean-field theory
Authors: Binney J J , Dowrick N J , Fisher A J , Newman M E J
Published: November 2023

In the previous chapter we saw that it is possible to make a great deal of progress in the study of particular models by real-space renormalization methods. These methods are very elegant and can explain why critical exponents arise and how they are related to each other. However, they are also very specific: it requires considerable ingenuity to invent an accurate (and tractable) real-space scaling transformation for any given model, and even when one has succeeded it is not normally very helpful in tackling the next problem.
The renormalization group
Authors: Binney J J , Dowrick N J , Fisher A J , Newman M E J
Published: November 2023

We are part of the way towards understanding the Landau-Ginzburg model in the critical regime. We have been able to calculate two critical exponents, one of which describes the system at T = Tc and the other at T ≠ Tc. If we are prepared to accept the scaling laws for which we found experimental evidence in Chapter 1, and theoretical evidence in Chapter 5, we can stop there; all four remaining critical exponents follow. However, this is rather unsatisfactory. In Chapter 5 we saw that the scaling relations can be deduced from the properties of the critical fixed point that is reached by repeatedly reblocking and rescaling the system; it would be good to provide a similarly general derivation in the context of the Landau-Ginzburg model.
The lower critical dimension
Authors: Binney J J , Dowrick N J , Fisher A J , Newman M E J
Published: November 2023

In §§3.2 and 3.3 we saw that both the Ising model and the spherical model have a lower critical dimension, dLC: the highest dimension at and below which the model is incapable of displaying long-range order. In §3.2 we understood physically why this was so for the Ising model: the size and thus the energy of an interface between two domains of n mutually aligned spins decreases with the dimension d, and when d is diminished to the entropy increase associated with increasing the number of such domains outweighs the energetic cost of extra interfaces, no matter how low the temperature is (providing it exceeds zero). In this chapter we study this phenomenon, especially the dependence of dLC on the dimensionality D of the order parameter ϕ, in the context of the Landau-Ginzburg model.
Storage and handling of liquefied gases
Authors: White Guy K , Meeson Philip J
Published: November 2023

It is a question of taste or age whether you use the term ‘dewar’ or not for storage vessels made of various materials and of various shapes. Whatever the case we should remember the seminal contribution of Sir James Dewar in 1898 with his evacuated and silvered glass vessel. This allowed him to produce a visible quantity of liquid hydrogen for the first time. It still seems appropriate to call glass cryogen containers ‘dewars’ but for metal and plastic containers it is a matter of choice. Efficient long-term storage has always been important for liquid oxygen on the industrial scale. Now this extends to other gases which are either industrially important or used in lengthy measurements. Important factors in storage are the difference in temperature of the cryogen and its surroundings as well as the latent heat of vaporization.
Below 0.3 K
Authors: White Guy K , Meeson Philip J
Published: November 2023

The lighter isotope of helium, 3He, has the lowest boiling point of any liquid, being 3.19 K. As described in Chapter 7, by reducing the vapour pressure temperatures below this may be realized by simple evaporative cooling. With the best available pumps in use this temperature is close to 0.25 K. Clearly rather different cooling techniques must be used below this. There are two main types of refrigerator in use in this regime: the dilution refrigerator and the adiabatic demagnetization refrigerator using nuclear magnetic moments. The latter remains primarily of research laboratory construction due to its limited commercial viability. In contrast the construction of dilution refrigerators has moved progressively from the research laboratory to the commercial arena, to the extent that only specialists researching the optimal operation of such machines would now consider building their own device. There are other types of refrigerator in use in this temperature regime, mostly for specific or unusual needs and of often largely historical interest. These are dealt with at the end of this chapter. We shall concentrate for the most part on how to make use of a dilution refrigerator, and on the construction and use of adiabatic demagnetization refrigerators.
Other techniques
Authors: White Guy K , Meeson Philip J
Published: November 2023

The earlier chapters should have made obvious the importance of high vacua in reaching and maintaining low temperatures. The present chapter discusses the main types of vacuum pumps, vacuum gauges and sealing techniques. More details of their role in small and large systems-cryogenic and otherwise-can be found in the many textbooks on vacuum technology (e.g. Dushman 1962; Yarwood 1967; Holland et al. 1974; Roth 1982). At low temperatures, the cryogen itself is a source of pumping-cryopumping. However, low temperatures present another problem, namely the brittle nature of the seals which are used at normal temperatures. Many rubber gasket or rubber O-ring seals are no longer practicable for vacuum-tight assemblies at low temperatures, witness the Challenger disaster. In Section 10.3 of this chapter a brief account is given of soft-metal O-ring seals and some low-melting-point solders which are useful in making vacuumtight joints which can be cooled and can also be ‘broken’ and remade fairly readily. Some other type of vacuum seals and cements as well as the use of metal-glass seals at low temperatures are described later in the chapter.
Order and disorder in spin systems
Authors: Krauth Werner
Published: November 2023

In this chapter, we approach the statistical mechanics and computational physics of the rising model, which has inspired generations of physicists. This archetypal physical system undergoes an order-disorder phase transition. The rising model shares this transition and many other properties with more complicated models which cannot be analyzed so well. The first focus of this chapter is on enumeration, which applies to the rising model because of its finite number of configurations, even though this number grows exponentially with the lattice size. We shall enumerate the spin configurations, and also the loop configurations of the rising model’s high-temperature expansion, which can be summed for very large and even infinite lattices, leading to Onsager’s analytic solution in two dimensions.
Entropic forces
Authors: Krauth Werner
Published: November 2023

In the present chapter, we revisit classical entropic models, where all configurations have the same probability. This sight is familiar from the hard-core systems of Chapter 2, where we struggled with the foundations of statistical mechanics, and reached a basic understanding of molecular dynamics and Monte Carlo algorithms. At present, we are more in terested in describing entropic forces, which dominate many effects in soft condensed matter (the physics of biological systems, colloids, and polymers) and are also of fundamental interest in the context of order disorder transitions in quantum mechanical electronic systems. The chapter begins with a complete mathematical and algorithmic solution of the problem of one-dimensional hard spheres (the “random clothes-pins” model) and leads us to a discussion of the Asakura-Oosawa depletion interaction, one of the fundamental forces in nature, at least in the realm of biological systems, colloids, and polymers.
The evolutionary psychology of human physical attraction and attractiveness
Authors: Thornhill Randy , Gangestad Steven W
Published: November 2023

Human physical attractiveness research recently has become a topic surrounded by fanfare, both in the public realm and the scientific circle. Findings about the topic, discovered from hypotheses inspired by the evolutionary approach, have been showcased in numerous television productions worldwide, and in other media channels. The media attention reveals that many people are interested in their preoccupation with looks and the findings are providing them access to its basis, both the physical traits assessed and the evolutionary function of aesthetic judgments. Moreover, the findings promise to place attractiveness research among the major success stories of cognitive science.
Combined Operations
Authors: Brown Andrew
Published: November 2023

In 1941 the BBC began a weekly radio programme called the Brains Trust. It was to prove popular and uplifting to a nation straining to resist the Nazis. The undoubted star was ‘Professor’ Cyril load, the head of Birkbeck’s philosophy department, but not in fact a professor of the University. To give himself time to answer a question, he would invariably start with the gambit, ‘It all depends what you mean by. . .’ Bernal was another regular member of the Trust, and was valued, amongst other qualities, as being a match for the populist load. The Brains Trust on 7th December 1941 comprised load, Bernal, Cyril Connolly (the essayist), a clergyman and a naval commander. Sage was in his element. The first question about the Aurora Borealis, from a twelve-year-old boy, was naturally his to answer. The next, ‘What service does the speculator on the Stock Exchange render to the community?’ found no takers and so Bernal offered an opinion. After giving a textbook economics answer on competitive markets arriving at the ideal value of a security ‘by a mystical concourse of wills’, he went on to say that he did not believe a word of it: the speculator was either gambling or attempting to corner the market.
The Physical Basis Of Life
Authors: Brown Andrew
Published: November 2023

Even in the darkest days of World War Two, the BBC adhered to Lord Reith’s maxim of informing, educating and entertaining the public. In March 1942, as part of a series ‘Science lifts the veil’, Sir William Bragg interviewed Sage about ‘The problem of the origin of life’. It had been Bragg who arranged for Bernal to give a series of lectures on ‘The molecular architecture of biological systems’ at the Royal Institution in 1938, and the broadcast was to some extent a summary of those talks. Bernal again referred to the gap between the molecular world studied by biochemists and the larger objects that could be seen under the microscope – the gap in which most structures important for life exist. In addition to the ultracentrifuge and X-ray diffraction, there was by 1942 a new tool for exploring the gap: the electron microscope. Bernal explained how the Tobacco Mosaic Virus (TMV) that he studied by X-ray diffraction had now been visualized directly by electron microscopy (he tactfully omitted to mention that this work took place in Berlin).
Mathematical Models in Applied Mechanics
Authors: Tayler A B
Published: November 2023

This textbook demonstrates the power of mathematics in solving practical, scientific, and technical problems through mathematical modelling techniques. It has been designed specifically for final year undergraduate and graduate students, and springs from the author's extensive teaching experience. The text is combined with twenty-one carefully ordered problems taken from real situations, and students are encouraged to develop the skill of constructing their own models of new situations.
Wave Motion
Authors: Tayler A B
Published: November 2023

This equation is the result of resolving the forces and mass acceleration on a small element of the string in the ydirection.
Diffusion
Authors: Tayler A B
Published: November 2023

In the two preceding chapters we have examined problems which were hyperbolic and elliptic, where for a second-order equation either two or no characteristic directions exist at each point respectively.
Biodiversity and ecosystem functioning: the emergence of a synthetic ecological framework
Authors: Naeem s. , Loreau M , lnchausti P
Published: November 2023

Earth’s biota is not a passive epiphenomenon of Earth’s physical conditions and geochemical processes. Through the collective metabolic and growth activities of its trillions of organisms, Earth’s biota moves hundreds of thousands of tons of elements and compounds between the hydrosphere, atmosphere, and lithosphere every year. It is this bio geochemical activity that determines soil fertility, air and water quality, and the habitability of eco systems, biomes, and ultimately the Earth itself (Lovelock 1979; Butcher et al. 1992; Schlesinger 1997). Indeed, biogeochernistry makes Earth a unique planet in the solar system (Ernst 2000).
Plant diversity and composition: effects on productivity and nutrient dynamics of experimental grasslands
Authors: Tilman D , Knops J , Wedin D , Reich P
Published: November 2023

There are few times in science when as many novel hypotheses are developed as when new results challenge an existing paradigm. Such was the case when, by 1997, recent studies suggested links between diversity and ecosystem processes (e.g. Frank and McNaughton 1991; McNaughton 1993; Dodd et al. 1994; Naeem et al. 1994a, 1995; Tilman and Downing 1994; Tilman et al. 1996, 1997a; Hooper and Vitousek 1997; Naeem and Li 1997). Some of the major conclusions of the preceding two decades-its paradigms-had been that diversity was controlled by disturbance and productivity, and that ecosystem functioning was controlled by the traits of the dominant resident species.
Multi-trophic dynamics and ecosystem processes
Authors: Raffaelli D , Putten W H van der , Persson L , Wardle D A , Petchey O L , Koricheva J , Heijden M van der , Mikola J , Kennedy T
Published: November 2023

It is axiomatic in ecology that the dynamics of one set of species cannot be understood without reference to the dynamics of other species and processes. For instance, biodiversity loss within a trophic level is likely to impact on species at other levels, whether directly through changes in competitive and consumer-resource interactions, or indirectly via changes in ecosystem processes (Fig. 13.1). Such interactions imply that predicting the consequences of biodiversity loss for ecosystem processes will be difficult, especially when, as is often the case, there are simultaneous reductions in diversity at more than one trophic level.
Species diversity, functional diversity, and ecosystem functioning
Authors: Hooper D U , Solan M , Symstad A , áz S Di , Gessner M O , Buchmann N , Degrange V , Grime P , Hulot F , Mermillod-Blondin F , Roy J , Spehn E , Peer L van
Published: November 2023

Experiments assessing the effects of biodiversity on ecosystem functioning initially aimed at establishing whether such relationships exist (e.g. Naeem et al. 1995; Tilman et al. 1996; Jonsson and Malmqvist 2000; Engelhardt and Ritchie 2001). These phenomenological studies were useful for helping to identify patterns and articulate further questions. However, using species richness as a simple mea sure of biotic diversity, as they did, had no explicit explanatory power: ecosystem level processes are affected by the functional characteristics of organ isms involved, rather than by taxonomic identity (Odum 1969; Pugh 1980; Grime 1988).
Measurement of Nuclear Moments
Authors: Castel B , Towner I S
Published: November 2023

Methods of measuring nuclear moments in most cases depend on the interaction of the nuclear moment with either an applied external magnetic field or with internal atomic or molecular fields. As a consequence the experimental investigation determines a product of the moment and the magnetic field strength at the nucleus. Thus the extraction of one part, say the nuclear moment, requires detailed knowledge of the counterpart in the product, the field strength. When the field at the nucleus is an externally applied field then there is little uncertainty in knowing its strength and the moment is determined with good accuracy. The nuclear magnetic resonance technique, to be discussed in Section 2.2, is an example of such a case.
Isovector Electric GRs
Authors: Harakeh M N , van der Woude A
Published: November 2023

In this chapter an overview will be presented of the isovector GRs built on the ground state of nuclei, the giant dipole resonance being the oldest and best known one. Macroscopically these resonances can be understood as out-of- phase vibrations of neutrons against protons (polarisation modes). They are characterised by the quantum numbers ΔT = 1, ΔS = 0 and ΔL = 0, 1, As discussed in Chapter 3, ΔT = 1, ΔS = 0 transitions can be excited either by γabsorption (or emission) and inelastic hadron scattering with ΔT3 = 0 or by specific charge-exchange reactions with ΔT3 = ±1. Compared with isoscalar transitions, the new feature is that isovector excitations, which involve the isospin operator τ, when induced in a nucleus with a ground-state isospin (T, T3)  -≠- 0, give rise to an (isospin) splitting of the observed strength. This is schematically indicated in Fig. 5.1.
Enzyme Inhibitors as Drugs: From Design to the Clinic
Authors: Luscombe D K , Tucker M , Pepper C J , Nicholls P J , Sandler M , Smith H J
Published: November 2023

Characterization of the biochemical pathways involved in many of the physiological activities which take place within the cell, and their relevance to disease processes, has resulted in the development of a number of clinically useful drugs which owe their effectiveness to the ability to inhibit a specific enzyme. This particular approach to the development of new therapeutic agents has gathered momentum over the past decade, not least because it offers a means of increasing the selectivity of a substance for a particular target site. It should be stressed that, once an enzyme system involved in disease has been identified, the design of a suitable inhibitor is a lengthy procedure. It is likely to be at least 10 years before a substance identified as a potentially useful enzyme inhibitor in the laboratory will reach the clinic and establish itself as a useful therapeutic agent. During this period, steps are taken to ensure that a drug is designed which will not only elicit the desired clinical response, but will be relatively free of sideeffects and lack toxicity. The aim of this chapter is to provide the reader with an overview of many of the factors that have to be considered when developing a drug for clinical use. Attention is focused on factors influencing drug absorption, distribution, and elimination, the problems associated with drug stereoisomerism, and finally a brief outline of the toxicity tests that are required to demonstrate drug safety.
Computer-aided Molecular Design of Enzyme Inhibitors
Authors: Slater A M , Timms D , Wilkinson A J
Published: November 2023

Historically, inhibitors of enzymes have been discovered by random screening or designed by analogy with elements of the enzyme ‘s catalytic pathway. Thus inhibitors based on substrates, transition states, and products have been produced by a procedure that relies on an understanding of the enzyme mechanism, together with some innovative chemical thinking. Molecular modelling techniques can significantly enhance this process, and in addition they provide the opportunity to aid the discovery of completely novel inhibitors.

In most instances, the chemist starts with a lead compound discovered via the more conventional methodology referred to above. If the inhibitor is required to function as a drug, there will usually be a need to modify this compound to achieve a desired profile of some form. This may involve attempts to find a compound of higher intrinsic inhibitory potency or increased selectivity. Additionally, physical and chemical properties may need modification to attain compounds that are, for example, orally active or which have better in vivo activity or reduced toxic side-effects.
Wave Properties of the Neutron and Types of Interaction
Authors: Alexandrov Yu. A , Drozdova T F
Published: November 2023

The discovery of the neutron in 1932 has undoubtedly had the most profound consequences. With this discovery began the era of nuclear physics in which quick advances gave birth in the middle of this century to nuclear technology and modern particle physics. Since then much has been learned about the neutron. Its interaction with nuclei is rather well studied (the construction of nuclear reactors would be impossible without this). The mass, spin, and magnetic moment of the neutron have been determined, and the knowledge of these, as well as the absence of an electric charge, have made the neutron a most convenient tool for research, for example, in condensed matter physics. Recent studies have made it possible to develop an idea of the neutron’s structure, in which the neutron appears as a particle of complex structure: at least its behaviour on interaction with matter differs from that of a point-like particle.
The Neutron and Gravity
Authors: Alexandrov Yu. A , Drozdova T F
Published: November 2023

The general assertion that acceleration due to gravity is a universal constant for all matter has been supported by the extremely precise measurements of Eötvös et al. and more recently by the substantially improved measurements of Roll et al.and then of Braginski and Panov.The latter established that there was no difference in the ratios of gravitational to inertial mass for aluminium and platinum to within 0.9 × 10-12 (at the 95 per cent confidence level). By comparing the free fall of microscopic PbCl (neutron-proton ratio R = 1.45) and copper (R = 1.19) it may be concluded that neutrons and protons in nuclei experience the same gravitational accelerations to within about 2 × 10-9  g  f. A measurement by Esterman et al.[68] demonstrated an identical gravitational acceleration of free caesium and potassium atoms in atomic beams. The universality of the acceleration due to gravity was confirmed by the measurements reported by Witte born and Fairbank[69] on the observation of the free fall of electrons and by the well-known experiments with photons performed by Pound and Rebka.
Electric Dipole Moment of the Neutron
Authors: Alexandrov Yu. A , Drozdova T F
Published: November 2023

The existence of the electric dipole moment (EDM) of elementary particles (particularly of the neutron) is associated with their symmetry properties. The discovery of parity violation has aroused a special interest in discrete transformations: charge conjugation (C), inversion of coordinates (P), and time reversal (T). Detailed reviews on the problem are given in Refs 218 and 219. A charge conjugation operation means the replacement of all particles by their antiparticles. A charged or a not truly neutral particle transforms into another, for example an electron into a positron. A truly neutral particle (e.g. a photon or a n° meson) transforms into itself. Each transformation implies a quantum mechanical quantity, which either reverses or preserves its sign. The charge conjugation reverses the sign of the charge (electronic, baryonic, leptonic) of the particle (Q → −Q), magnetic moment (μ → −μ), magnetic field strength (H → −H), and electric field strength (ℰ → −ℰ), but preserves the sign of the momentum (p → p) and spin (σ → σ). An experimentally observed particle-antiparticle symmetry reveals itself in the requirement of the invariant of physical laws under charge conjugation (C): if a certain physical process occurs in nature, the physical process in which the particles have been replaced by antiparticles occurs with the same probability (the law of C parity conservation). Up to 1956 the above formulated law was believed to hold for any interactions of any physical objects. In 1956 the breakdown of invariance under charge conjugation in weak interactions was discovered. For example, the free neutrino was found to be polarized in the opposite direction to its momentum and antineutrino in the direction of the momentum. The charge conjugation operation applied to the neutrino (or antineutrino) leads to a situation having no place in nature.
Lattice vibrations in semiconductors
Authors: Balkanski M , Wallis R F
Published: November 2023

An important source of deviations from periodicity in a crystal is the displacement of an atom from its equilibrium position. These deviations arise naturally from the thermal energy of the atoms. If the crystal is in a stable configuration, the displacement of an atom leads to a force that tends to restore the atom to its equilibrium position. However, the kinetic energy of the atom causes it to overshoot the latter. As a result the atom vibrates about its equilibrium position. The forces of interaction between atoms couple the atomic vibrations together, giving rise to lattice vibrations.
Heterostructures: electronic states
Authors: Balkanski M , Wallis R F
Published: November 2023

In the preceding three chapters we have considered junctions formed by taking a single semiconductor and doping adjacent parts of the sample with two different types of impurities, one acceptor and the other donor. We now consider junctions in which the p- and n-type parts are different semiconductors. These junctions have some properties that are similar to those of homojunctions, but other properties that are quite unique.
Optical properties of heterostructures
Authors: Balkanski M , Wallis R F
Published: November 2023

For bulk semiconductors the determination of the optical absorption coefficient is relatively simple: one measures the attenuation of a light beam passing through a sample of suitable thickness. In the case of quasi-two-dimensional structures the measurement is complicated by the high anisotropy of these systems and their very small thicknesses.
Unitary Groups
Authors: Stancu Fl
Published: November 2023

Unitary groups have extensive applications in physics. They describe intrinsic properties of quantum particles or collective degrees of freedom in composite systems. For example, the group SU(3) was used by Elliott to explain rotational levels of deformed nuclei (Elliott 1958, Elliott and Harvey 1963; for a review, see Hecht 1964).
The beginnings and the writing of the Principia
Authors: Chandrasekhar S
Published: November 2023

Some acquaintance, with the antecedents of the less than two years-from the late autumn of 1684 to the early summer of 1686-in which Newton composed the entire Principia, is essential to a proper appreciation of the range and variety of the topics that are treated in it in depth and with rare perception. The literature on this ‘pre-Principia’ period is vast; but it is mostly not relevant to the purposes of this book as stated in the Prologue. And consistent with those purposes, the account that follows is a bare record of events that are not disputed.
On the motion of particles under centripetal attraction: an introduction to Newton’s treatment
Authors: Chandrasekhar S
Published: November 2023

Newton’s treatment of Kepler’s laws of planetary motion is among the most celebrated parts of the Principia. To appreciate the novelty and the originality of Newton’s treatment, one must have in mind, for comparison, a more conventional treatment to which one is accustomed. Besides, it is important to have a treatment of elliptical motion under the inverse-square law of attraction that is readily adapted to obtaining the equations governing the perturbations of ellipitic motion based on the ‘variation of the constants’. For as Tisserand* has stated, Newton undoubtedly had in his possession these variational equations for this treatment of lunar perturbations.
The method of the variation of the elements of a Kepler orbit and Newton’s lunar theory: An introduction to Propositions LXV-LXIX
Authors: Chandrasekhar S
Published: November 2023

As we have stated in the introduction to Chapter 12, Tisserand was of the opinion that Newton had derived for himself the equations expressing the variations with time of the elements of the Kepler orbit under the action of an external force ff —elements that would otherwise have been constants; and that Proposition LXVI and its 22 corollaries provide the principal basis for this inference (see Chapter 14). To make Propositions LXV-LXIX more readily understandable, we shall give in this chapter, in the spirit of the Principia, an elementary self-contained account of the method of the variation of the elements and its application to the perturbations of the Moon. The present chapter is in effect a continuation of Chapter 4 whose notations we shall follow.
‘The superb theorems’
Authors: Chandrasekhar S
Published: November 2023

In Chapter 1, we have already described the antecedents of Newton’s discovery of the theorem that was later to be described as ‘superb’ by J. W. L. Glaisher. Therefore, on this occasion, we shall, as the saying goes ‘cut the cackle and come to the bosses’. We shall begin with an explanation which Newton provides later: By the surfaces of which I here imagine the solids composed, I do not mean surfaces purely mathematical, but orbs so extremely thin, that their thickness is as nothing; that is, the evanescent orbs of which the sphere will at last consist, when the number of the orbs is increased, and their thickness diminished without end. In like manner, by the points of which lines, surfaces, and solids are said to be composed, are to be understood equal particles, whose magnitude is perfectly inconsiderable.
Prolegomenon
Authors: Chandrasekhar S
Published: November 2023

In the preceding books I have laid down the principles of philosophy; principles not philosophical but mathematical: such, namely, as we may build our reasonings upon in philosophical inquiries. as To this purpose the philosophers say that Nature does nothing in vain, and more is in vain when less will serve; for Nature is pleased with simplicity, and affects not the pomp of superfluous causes. As to respiration in a man and in a beast; the descent of stones in Europe and in America; the light of our culinary fire and of the Sun; the reflection of light in the Earth, and in the planets.
On comets
Authors: Chandrasekhar S
Published: November 2023

The seven Lemmas, IV-X, and the three Propositions, XL-XLII, devoted to comets and occupying 43 pages (439-481) in the original 1713 second edition of the Principia are quite exceptional: basic matters are treated in the normal tenor of the Principia in Lemmas V-X and in the three propositions in barely ten pages; the remaining 33 pages are concerned with the results of numerical computations of cometary orbits and the physics of comets.
The physics of fluids
Authors: Guyon Etienne , Hulin Jean-Pierre , Petit Luc , Mitescu Catalin D
Published: November 2023

From a microscopic viewpoint, the study of the physics of fluids can be considered as a branch of thermodynamics. In a classical thermodynamic approach, we study the equilibrium states of pure substances-solids, liquids, and gases-and the changes of state between these several phases.
Laminar boundary layers
Authors: Guyon Etienne , Hulin Jean-Pierre , Petit Luc , Mitescu Catalin D
Published: November 2023

The concept of a boundary layer is crucial to the understanding of the flow around an obstacle at large Reynolds numbers. Far from the object, as long as the incident flow is not turbulent. the terms corresponding to viscous forces, in the Navier-Stokes equation, are negligible; the flow velocity profile is then effectively that of an ideal fluid.
From the finite to the infinite
Authors: Sutton Adrian P
Published: November 2023

In this section we shall consider a series of hypothetical molecules consisting of chains of between two and an infinite number of hydrogen atoms. One aim is to show that the quantum mechanical description of bonding in an infinite linear chain is essentially no different from what we have already discussed in Chapter 2 for a diatomic molecule. In this way we hope to convince you that solids may be thought of as infinite molecules, but, of course, in three dimensions. Another aim is to set up the machinery that we need to discuss an infinite periodic system, such as k-space, Bloch functions, Brillouin zones, the Fermi energy, and so on. Once we have done that then moving onto a three-dimensional perfect crystal is more complicated, but no new ideas are needed.