bluuebunny/crossref_metadata_2025 huggingface dataset:
s-p bonding-a case study in silicon
Authors: Sutton Adrian P
Published: November 2023

In this chapter we shall enlarge the basis set that we assume for each atom to include p electrons. It is necessary to do this in order to understand the cohesion of many elements of the periodic table and their compounds. In Chapter 9 we shall consider bonding caused by interactions between d states. By surveying the elements of the periodic table we see that s-p bonding occurs among the valence electrons of the elements of groups I-VII. The elements of the first three groups have closed packed metallic structures, i.e. f.c.c., h.c.p., and b.c.c. As we go down the elements of group IV from C to Si, Ge, Sn, and Pb, the stable crystal structures change from three-fold coordination in graphite, to four-fold coordination in the diamond cubic structure in Si and Ge, to 12-fold coordination in f.c.c. Pb. In group V (apart from N which forms diatomic molecules) the pnictides take structures based on the stacking of three-fold coordinated buckled layers of atoms. In group VI the chalcogenides take structures based on two-fold coordinated helical chains. The group VII halogens crystallize as diatomic molecules (and thus with a coordination number of 1) which are held together by weak van der Waals interactions. Thus, s-p bonding in the elements gives rise to a wide variety of crystal structures and coordination numbers.
Properties of free electron metals
Authors: Sutton Adrian P
Published: November 2023

We noted in the previous chapter that Drude’s free electron model of a metal failed in one principal aspect: it regarded the electrons as classical particles obeying Maxwell-Boltzmann statistics. Sommerfeld’s free electron model recognized that the electrons obey quantum mechanical laws. Owing to the electron spin of 1/2, electrons are fermions and they obey Fermi-Dirac statistics. Each quantum state of the system can be occupied by at most two electrons, one with spin up and the other with spin down.
Recent developments and future prospects
Authors: Duke Philip John
Published: November 2023

Synchrotron radiation is a highly versatile research tool which provides electromagnetic radiation over a wide range of wavelengths. It is highly collimated. When an undulator is the source, the radiation, especially in the X-ray region, is of unparalleled brightness. In this concluding chapter we indicate how synchrotron radiation sources are being developed at the present time. These developments are being driven by the requirements of the synchrotron radiation users themselves.
Introduction And Summary
Authors: Asner Fred M
Published: November 2023

The present book on Superconducting High Field Magnets contains 13 chapters. It is intended to cover the relevant interdisciplinary fields of applied physics with the aim of transmitting to the professional reader the vast theoretical work and experimental data which should help him to design, build and operate superconducting magnets and magnet systems. Chapter 2, ‘Basic features of superconductivity,’ starts with the experimental discovery of the phenome by K. Ones and analyses the intriguing fundamental experiment of Meissner and Ochsenfeld, which triggered vast theoretical and experimental activity with the aim of understanding and explaining superconductivity. The two-fluid thermodynamic theory and the intuitive but non-rigorous approach of the London brothers are presented, and this leads to the rigorous BCS theory, fully explaining the phenomenon. Basic parameters like critical magnetic fields and temperature, superconducting screening current, elementary quantized fluxoid, penetration depth and pinning forces are dealt with and the particular cases of Type I and Type II superconductors are given. High temperature superconductors are not dealt with.
Magnetization And Ac Losses In Superconductors
Authors: Asner Fred M
Published: November 2023

Magnetization losses in superconducting filaments and other losses in superconductive wires, composites and cables in time-varying magnetic fields are of considerable importance to magnet design. Important theoretical and experimental investigations in this domain had been performed since the understanding of hard Type II superconductors due to the work of Bean and Kim (see chapter 2), Anderson et al. [1], which led to the development of the two main technical superconductors and and of other potential candidates, to be treated in Chapter 5.In the early 1970s high energy particle accelerators with superconductive dipole and quadrupole magnets and with duty cycles close to those of accelerators equipped with classical magnets were investigated; rise times of∼ 1 s and duty cycles of a few Hz had been assumed. Loss calculations have shown that such ‘fast’ cycled machines would require more elaborate composites and cables and higher performance cooling systems compared to quasi-de operated superconducting accelerators. It has been a fortunate coincidence that a parallel evolution pointed towards such an operation. Slow, long duration beam extraction and spilling techniques had been developed leading to cycles with longer flat tops of several minutes. When the advantages of particle colliders over fixed target machines became more and more evident [2,3,4] with flat tops extending to several hours or days, this mode of operation was also beneficial for the development of adequate superconducting de magnets.
Mechanical Computations And Design Principles For Superconducting Magnets
Authors: Asner Fred M
Published: November 2023

A sound and thorough mechanical design kf high field superconducting magnets is of prime importance for their successful operation. In the early days of magnet development the computational and design effort was mainly concentrated on the analysis and realization of suitable field configurations, while the mechanical problems had been treated in a rather marginal way. The poor test results, failures, and premature quenches experienced with these early magnets indicated the need for a thorough understanding, analysis, and solution of the mechanical problems as well.
Penning Trap Mass Spectrometer
Authors: Bollen G , Kluge H -J
Published: November 2023

It has been proved that Penning traps are efficient tools for high-accuracy mass determinations. With these devices the mass ratios of a number of stable or long-lived light particles, as for example electron and positron, electron and proton, proton and antiproton, helium-3 and tritium or the molecules N2 and CO, have been determined with unsurpassed accuracy.
Nuclear Stability, Hadron, And Cluster Emission
Authors: Poenaru Dorin N , Greiner Walter
Published: November 2023

The present chapter is devoted to the problem of nuclear stability against various spontaneous decay modes, in which a parent nucleus A, Zin its ground state is split into nuclei A1, Z1 and A2, Z2 in a way that conserves the hadron numbers A — A{ + A2, Z — Z\ + Z2.
Low-Dimensional Semiconductors
Authors: Kelly M J
Published: November 2023

This text is a first attempt to pull together the whole of semiconductor science and technology since 1970 in so far as semiconductor multilayers are concerned. Material, technology, physics and device issues are described with approximately equal emphasis, and form a single coherant point of view. The subject matter is the concern of over half of today's active semiconductor scientists and technologists, the remainder working on bulk semiconductors and devices. It is now routine to design and the prepare semiconductor multilayers at a time, with independent control over the dropping and composition in each layer. In turn these multilayers can be patterned with features that as a small as a few atomic layers in lateral extent. The resulting structures open up many new ares of exciting solid state and quantum physics. They have also led to whole new generations of electronic and optoelectronic devices whose superior performance relates back to the multilayer structures. The principles established in the field have several decades to go, advancing towards the ultimate of materials engineering, the design and preparation of solids atom by atom. The book should appeal equally to physicists, electronic engineers and materials scientists.
Silicon and silicon hetero junctions
Authors: Kelly M J
Published: November 2023

Si dominates the electronics industry, being associated with more than 90 per cent of the added value in components and subsystems (Sze 1988), and if it were a direct-gap material as required for optical applications, the 111-V and other semiconductors would have remained curiosities. Compared with all other semiconductor materials, Si substrates come in large areas. They have high mechanical stability, modest electrical insulation, and a good thermal conductivity. The ease of forming a thin stable high-resistance thermally grown oxide which is capable of withstanding high electric fields and of being patterned by a variety of methods is also a strong advantage. However, the extra speed of carriers in 111-V materials, the negative differential mobility of GaAs at high fields, and light emission from direct-gap 111-V materials (as light-emitting diodes and as laser diodes) has given semiconductors other than Si a chance. A further advantage, peculiar to GaAs, is that very-high-resistance substrates are available, and this property is maintained during the thermal, chemical, and other cycles associated with microwave device fabrication. During equivalent processing of Si a low level of mobile carriers is introduced into the substrate, and their response to rapidly changing electric fields introduces an extra reactive impedance to the microwave signals and degrades the performances of devices at high frequencies. The advent of hetero junctions has continued to give high-performance 111-V devices a lead over their Si counterparts where there is direct competition (as in high-speed microwave and low-density logic applications). This advantage was further helped by the availability of lattice-matched combinations of materials. The technology of hetero junctions has made possible new generations of devices and new device functions in 111-V materials. With time, the incorporation of strain has been mastered, and some effects of strain, particularly on the hole band structure, have been deliberately exploited to give superior device performance.
Theoretical developments in static light scattering from polymers
Authors: Benmouna Mustapha , Reed Wayne F
Published: November 2023

The theory of light scattering was first put forward by Lord Rayleigh, in a series of papers in which he discussed the case of particles with a small size compared to the wavelength of the incident light. Debye extended this theory to large particles, including the effects of intramolecular interference between waves scattered by different parts of the same molecule. In particular, he derived the form factor of a flexible Gaussian chain in the absence of excluded volume interaction (see eqn (1.17)). This expression is extremely useful for analysing scattering data from polymers. Rayleigh-Debye theory was extended by Zimm, who calculated the scattering intensity of a dilute polymer solution in good solvent conditions in which the excluded volume interaction is important.
Low angle light scattering and its applications
Authors: allamace Francesco M , Micali Norberto
Published: November 2023

The length scale ranging from some hundreds of Angstroms to micrometers is relevant in many different research areas of physics, chemistry and biology, and in particular in the interdisciplinary field of complex systems. The characteristic properties of these latter systems, i.e. polymers, polymer solutions, gels, charged colloids, microemulsions, micelles, liquid crystals, proteins, DNA solutions, living cells, etc., reflect structures or superstructures (cluster networks built up by precise aggregation phenomena) that fall in a length interval termed the mesoscopic region. In addition, many of these systems arrange themselves in extended networks with self-similar long-ranged structures characterized by scaling laws. A more complete understanding of such systems can be obtained by exploring many orders of magnitude in length.
The Equivalent Linear Sigma Model
Authors: Ripka Georges
Published: November 2023

The aim of this chapter is to transform the Nambu Jona-Lasinio action into the action of an equivalent linear sigma model. The equivalence holds when the cutoff which regulates the quark loop is large compared to the constituent quark masses. We shall find in fact that the cut-off is only about twice the constituent quark mass. In spite of this, the equivalent sigma model is a convenient way to understand the physics contained in the model and to make simple and realistic estimates of the model parameters. However, the equivalent sigma model hides many of the shortcomings of the model such as, for example, its inability to confine the quarks. The real physical content as well as the limitations of the Nambu Jona-Lasinio model become apparent when correlation functions and solitons are calculated (see chapters 7 and 9). This chapter also serves as a pedagogical introduction to some of the basic techniques used in the meson sector.
Correlation Functions In The Nambu Jona-Lasinio Model
Authors: Ripka Georges
Published: November 2023

The reader is advised to go through the calculations in chapter 5 if he wishes to familiarize himself with the techniques applied in this chapter. Reviews of the calculation of correlation functions in the Nambu Jona-Lasinio model can be found in [29, 52). In [98], euclidean correlation functions are compared with 'experimental' ones deduced from data by dispersion relations. We follow the methods developed in [30].
Overview Of Results In The Meson Sector
Authors: Ripka Georges
Published: November 2023

There are several reviews of chiral quark models, such as the Nambu Jona-Lasinio model, applied to the meson sector [29, 52, 115, 116, 117, 118] as well as innumerable applications. Each one stresses a different approach to the subject, although they all boil down to similar calculations. This chapter is an introduction to the vast literature on the subject, and further references appear in the text. We choose a limited number of observables and we expose the physical meaning of the calculations as well as the inevitable problems which are encountered.
Further Chiral Quark Models
Authors: Ripka Georges
Published: November 2023

The Nambu Jona-Lasinio is but one of several models which describe quarks interacting with chiral fields. In this chapter we review and compare other models which have been extensively used. They all have in common a quark loop term which describes quarks interacting with a chiral field.
The pressure of light
Authors: Akhmanov S A , Nikitin S YU
Published: November 2023

The momentum of an optical wave. Measurement of the pressure of light and Lebedev’s experiments. The pressure exerted by light on the classical atom. The angular momentum of an optical wave. The photon. Optical cooling.
The laser
Authors: Akhmanov S A , Nikitin S YU
Published: November 2023

Quantum properties of atoms and Bohr’s postulates. Optical quanta. Spontaneous and stimulated emission in a quantum-mechanical system. The operational principle and design of a laser. The characteristics of laser radiation. The generation of ultra-short pulses.
The diffraction of paraxial beams
Authors: Akhmanov S A , Nikitin S YU
Published: November 2023

Fresnel’s approximation in diffraction theory. Fresnel’s integrals and Cornu’s spiral. Fresnel diffraction by unidimensional structures. Fresnel diffraction by two-dimensional structures. The parabolic equation and quasi-optical approximation. Solution of the parabolic equation. The propagation and diffraction of a Gaussian beam. The focusing of a Gaussian beam. The application criterion for quasi-optical approximation.
Ice Models
Authors: Newman M E J , Barkema G T
Published: November 2023

Most of the models we have studied in the preceding chapters of this book have been variations of the using model. Although using models are the most important and best-studied class of models in statistical mechanics, it is useful for us to study other classes as well, since there are many concepts in the design of Monte Carlo algorithms which only arise when we look at other models. In this chapter we introduce the so-called ice models, which, as the name suggests, model some of the thermodynamic properties of ice, though they do so only in a rather primitive fashion. Ice models are similar to using models in that the microscopic variables making up the model are discrete quantities having just two possible values, positioned on a lattice. However, unlike the models of the previous chapters, these variables are now located on the bonds of the lattice, rather than the sites, and, as we shall see, this, in combination with some other features of ice models, makes for some interesting challenges in the design of Monte Carlo algorithms.
The Repton Model
Authors: Newman M E J , Barkema G T
Published: November 2023

In the preceding chapters of this book we have given a number of examples illustrating the use of creatively designed Monte Carlo algorithms to answer questions about problems in statistical physics. In this chapter we will apply the same techniques to a problem of great importance in biophysics, the problem of polymer electrophoresis. We will study the problem, as we have the others in the book, by simulation of a simplified model which captures the essence of the processes involved. This model is called the “repton model” and, as we shall see, it is very similar in spirit to the models we are familiar with from statistical physics. This should come as no great surprise; the demarcation of science into the separate disciplines of physics, biology, chemistry and so forth is, after all, an artifact of our own creation, and has little to do with the science involved. Indeed, it is the wide applicability of the ideas of physics to problems which traditionally have been classified as biophysics or genetics or biochemistry, which has led an increasing number of physicists to desert their conventional fields of study for other equally fertile ground.
Electronic Theory for Nonlinear Magneto-Optics
Authors: Hübner W
Published: November 2023

This effect reflects the symmetry of the surface structure and surface magnetism and has been proposed as an ultrafast spectroscopic probe for the investigation of two-dimensional mag netism.12-14 NOLIMOKE is very well suited for a direct investigation of surface structures and electronic and magnetic properties. Thus, two-dimensional ferro magnetic structures at surfaces, at interfaces, in thin magnetic films and in multilayers can he studied.
Sample preparation, sample environment and radiological safety
Authors: Willis B T M , Carlile C J
Published: November 2023

Because the neutron is electrically neutral, it penetrates most substances readily. The exceptions are hydrogenous materials and strongly absorbing materials, such as cadmium, gadolinium and boron. This penetrability not only means that the true internal microscopic behaviour of a solid or liquid can be probed but also that a sample under study can be held within bulky sample environments (e.g. cryostats, furnaces, pressure cells or reaction vessels) and, with properly collimated beam geometries, still give good quality data. For this reason neutrons are capable of exploring a wide range of thermodynamic variables. Temperatures from mK to thousands of degrees centigrade; pressures from mbars to Mbars; magnetic fields of 15 Tesla or higher; chemical reaction processes involving reaction vessels at elevated temperatures with gas overpressures; and kinetic processes such as extrusion, flow and shear: all these variables are accessible to neutron scattering.
Magnetohydrodynamic description of plasma
Authors: Dendy R O
Published: November 2023

So far, we have based our study of plasmas on the single particle dynamics of the constituent electrons and ions. We have used these dynamics as the basis for a dielectric description of the plasma. This approach has been very effective. The understanding of any physical system is aided by knowledge of its normal modes, and the dielectric approach has enabled us to formulate the normal modes of plasmas over a very wide range of frequencies. In Section 3.4, we studied normal modes with phase velocity VA defined by eqn (3.82), whose frequencies w lie well below the lowest characteristic single particle frequency, the ion cyclotron frequency Wei· Two features of these modes suggest that an alternative approach to low frequency plasma behaviour might be fruitful.
Hopping Conduction And Related Phenomena
Authors: Kamimura Hiroshi , Aoki Hideo
Published: November 2023

Hopping conduction is a well-known mode of conduction in various classes of less conductive materials. We have mentioned in Chapter 3 that hopping conduction is observed in doped semiconductors for low donor concentrations. By hopping is meant a conduction process in which localized electrons jump quantum mechanically from states to states.
Interacting electrons in the quantum Hall regime—the fractional quantum Hall effect
Authors: Kamimura Hiroshi , Aoki Hideo
Published: November 2023

We have seen that the application of a strong magnetic field makes the one onebody electronic states very singular in the two-dimensional (2D) electron system. When electron-electron interactions commence, the ground state of the system becomes a novel quantum state, which is another manifestation of the peculiarities of 2D systems in magnetic fields. The first indication of the drastic quantization was found experimentally when Tsui and coworkers (Tsui et al. 1982b) observed a strange phenomenon in the quantized Hall effect in a GaAs-AlGaA,s system in 1982 (Fig. 10.1).
Dynamical Properties Of Smectics And Columnar Phases
Authors: Gennes P G De , Prost J
Published: November 2023

In Chapter 5 we saw that the long-wavelength, low-frequency behaviour of nematics could be described by a continuum theory. Here we consider the equivalent approach for smectics and columnar phases. We use the general framework constructed by Martin, Parodi, and Pershan [1] since it allows the use of the same presentation for all systems. The hydrodynamics of smectics was first discussed in reference 2 and of columnar phases in reference 3 (reference 4 for the biaxial case).
Electrostatic interaction between different parts of an MIS structure and its influence on charge carrier transport
Authors: Dobrovolsky V N , Litovchenko V G
Published: November 2023

When electric current flows through the bulk of a uniform semiconductor, the electric charges involved are not linked by any electrostatic interaction with the charges outside the semiconductor and they are uniformly distributed in the bulk. Quite a different situation takes places in MIS structures. Here the carriers in the subsurface layer of the semiconductor are linked by an electrostatic interaction with the charges at the gate, and this effect changes the charge carrier concentration along the direction of current flow in the semiconductor, the longitudinal component of the field strength, and gives rise to a diffusion component in the current. In the case of the inversion channel of an MIS transistor, in addition to the electrostatic interaction between the semiconductor and the gate, another interaction between the inversion channel and the depletion layer must be taken into account, because it also causes such effects.
Polymers in Solution
Authors: Cloizeaux Jacques des , Jannink Gerard
Published: November 2023

The result of a collaboration between a theoretician and an experimentalist, this book is devoted to the static properties of flexible polymers in solution. It presents the vast progress made by both theory and experiment in recent years. Despite the variety in the chemical composition and physical properties of long polymer chains, when in solution they show a universality in their behaviour. On the experimental side, the use of photon and neutron scattering has led to a better understanding, while the use of computer simulation has also produced interesting results. This work is the result of a collaboration between a theoretician and an experimentalist, who have both worked for many years on polymer solutions.
General Description of Long Chains, Universality, Critical Phenomena, and Scaling Laws
Authors: Cloizeaux Jacques des , Jannink Gerard
Published: November 2023

The application of universality principles and the use of scaling laws in physics, particularly in the field of polymers has been developing gradually, say from I 950 to I 980. These notions have been introduced In order to describe random scale¬ invariant systems, whose importance had been recognized earlier. The manner in which this problem arose, appears clearly in the following text, taken from the introduction to the book The Aroms by Jean Perrin (1913).
Mathematical Models of Chains: Sta Tic Proper Ties
Authors: Cloizeaux Jacques des , Jannink Gerard
Published: November 2023

Though the static properties of polymers in solution are now quite well-known, only a small fraction of them has been proved in a perfectly rigorous manner. We owe the main results, concerning numbers of chains to the British mathematician Hammersley who studied the problem around 1960, and some refinements are due to Kesten (1963). These are summarized below in a modified form.
Standard Continuous Model and Perturbation Calculations
Authors: Cloizeaux Jacques des , Jannink Gerard
Published: November 2023

The interactions existing between segments of the same polymer or different polymers modify the properties of the system in a manner which can be treated by perturbation. The perturbation expansions that are used to study polymer solutions are generalizations of the Ursell-Mayer-Yvon expansions which apply to gas theory. This technique has been developed from 1972 onwards, especially in the United States and in Japan. The expansions start from a model. The most simple and common one is the famous continuous model which will be described in this chapter in great detail.
Partially Attractive Chains: Theoretical Results
Authors: Cloizeaux Jacques des , Jannink Gerard
Published: November 2023

When the temperature of a polymer solution diminishes, the attractive longrange forces become more efficient than the hard-core repulsive forces. At a temperature TFrecognized by Paul Flory in 1942, attractions and repulsions compensate. In this case, for a temperature slightly smaller than TF, the solution separates into two phases and this phenomenon is called demixtion.
Introduction
Authors: Chakrabarti Bikas K , Gilles Benguigui L
Published: November 2023

If one applies tensile stress on a solid, the solid elongates and gets strained. The stress (σ) - strain (ε) relation is linear for small stresses (Hooke’s law) after which nonlinearity appears, in some cases. Finally at a critical stress εf, depending on the material, amount of disorder and the specimen size etc., the solid breaks into pieces; fracture occurs. In the case of brittle solids, the fracture occurs immediately after the Hookean linear region, and consequently the linear elastic theory can be applied to study the essentially nonlinear and irreversible static fracture properties of brittle solids (Lawn and Wilshaw 1975, Thomson 1986, Evans and Zok 1986).
The Centre for Reviews and Dissemination
Authors: Sowden Amanda , Glanville Julie
Published: November 2023

In this chapter we outline the role of the Centre for Reviews and Dissemination (CRD) in providing evidence about the effects of interventions not only in health care but also in public health. In particular, we discuss certain methodological challenges posed by the complexity of public health interventions for the process of systematic review of evidence. We also highlight the general underdeveloped nature of the evidence base on the effectiveness and cost-effectiveness of public health inventions and the need for investment in rigorous evaluation to address this gap.
The Centre For Evidence-Based Public Health Policy: part of the ESRC Evidence Network
Authors: Petticrew M , Whitehead M , Bambra C , Egan M , Graham H , Macintyre S , McDermott E
Published: November 2023

The belief that health-care decisions should be informed by rigorous scientific reviews of the existing evidence is now relatively uncontentious. Interest in such ‘evidence-based’ approaches to decision-making has also spread rapidly beyond the world of health care to many other aspects of social policy, and we can now find references to evidence-based housing, policing, probation, social policy, transport, education defence, and social virtual centre, which began work in 2001, is a collaboration between researchers at three locations.
Social beliefs about gender differences
Authors: Breakwell Glynis M
Published: November 2023

The notion of ‘social beliefs’ is fraught with ambiguity. It has a siren quality which lures the brave into efforts after definition and comparisons with other problematic concepts such as attitudes, public opinion, social cognitions, social representations, conceptual schemata, or ideology.

Suffice it to say that for the purpose of this paper it is assumed that social beliefs are commonly held interpretations of socially important phenomena. They are what some others in this volume have termed ‘widespread beliefs’.

Any socially important phenomenon will have more than one set of social beliefs encircling it, since more than one group of interests will attach to it. Social beliefs are created within an intergroup context. They come into being because a group wishes to delineate the meaning or establish the ‘facts’ about a phenomenon. This erection of meaning and interpretation is self-serving, it will suit the interests and purposes of the group concerned. Each group has its own set of social beliefs organized into systems which justify its action, specify its identity, and serve its interests. Consequently, the greater the number of groups for whom a social phenomenon is relevant, the greater will be the variety and complexity of the social beliefs surrounding it. This becomes patently obvious in examining social beliefs about gender differences.
Medial premotor cortex (SMA) (area 6)
Authors: Passingham Richard
Published: November 2023

The previous chapter considered voluntary movements made in response to some prompt. The monkey pulls the lever when the red light appears; the patient salutes when the examiner commands. In both cases the act that is appropriate depends on the context, and the context is some event in the world. We may say that the individual ‘reacts’.
Ventral prefrontal cortex (areas 11, 12, 13, and 14)
Authors: Passingham Richard
Published: November 2023

There are few if any connections to the superior colliculi from the ventral convexity and orbital surface (Catsman-Berrevoets et al. 1979; Pries 1984). The ventral cortex connects instead to the amygdala and hypothalamus. Electrical stimulation of the postero-medial orbital cortex (areas B and 14) (Fig. 6.3, p.125) produces a variety of autonomic responses in monkeys (Kaada 1960). These include changes in blood pressure, decreased gastric motility, pupillary dilatation, piloerection, and alterations in respiration.
Basal ganglia
Authors: Passingham Richard
Published: November 2023

It might be thought that if the animal is to make the correct choice, the prefrontal cortex must access the limb mechanisms of motor cortex. If that was so, we might expect lesions of the motor cortex itself to impair performance on these tasks, but we know that they do not. Pribrnm et al. 0 955) studied two monkeys with radical bilateral ablations of motor cortex. The monkeys were not trained until they were much recovered. They learned the DR task in 210 and 270 trials: the mean for .’35 unoperated monkeys that had been tested in the same laboratory was 375 t1ials.
Thought and voluntary action
Authors: Passingham Richard
Published: November 2023

H is time to forget monkeys and their search for peanuts. There are other goals in life. This chapter takes us from the selection of pictures in the laboratory to Lhc choice of shops and restaurants in everyday life. In many laboratory tests, patients are required to choose between items. Like the monkeys, the subjects search for the correct item in an external array. It may be a picture or word, as on the subject-ordered task (Petrides and Milner 1982), or a card in a particular location, as on the spatial associative task (Petrides 1985).
Music and consumer behaviour
Authors: North Adrian C , Hargreaves David J
Published: November 2023

The commercial and industrial uses of music (see Bruner 1990; Gardner 1985a) account for billions of dollars worldwide, involved with such diverse activities as honouring royalty payments for using music in TV advertisements, installing music systems in shops, or promoting new pop music records and CDs. Given the frequency with which people are exposed to music on the radio or in shops or television advertisements, it is possible to argue that such commercial uses constitute one of the principal sources of our everyday exposure to music in the Western world. This remains the case despite the existence of pressure groups such as Pipedown in the UK, and arguments that commercial uses of music may have negative effects (e.g. Englis and Pennell 1994), be less appropriate than silence (Olsen 1994), and at times constitute noise pollution (cf. Hopkins 1994).
Theory of mind and autism: a fifteen year review
Authors: Baron-Cohen Simon
Published: November 2023

There is a danger when something gets discussed too much, its importance gets overlooked. ‘Theory of mind’ as a topic in developmental psychology may be facing that danger. Fifteen years ago, the topic was relatively under-researched, and its arrival into science opened a floodgate of research, much of which has been summarized in a number of influential books (Astington 1994; Astington et al. 1988; Baron-Cohen 1995; Baron-Cohen et al. 19936; Mitchell and Lewis 1995; Moore and Dunham 1996; Perner 1991; Wellman 1990; Whiten 1991). Fifteen years later, the field is that much more mature, and many of the relevant findings from normal development are summarized in the chapter by Wellman, this volume (Chapter 2). But readers should be on their guard not to consider the topic any less important today: a theory of mind remains one of the quintessential abilities that makes us human (Whiten 1993). By theory of mind we mean being able to infer the full range of mental states (beliefs, desires, intentions, imagination, emotions, etc.) that cause action. In brief, to be able to reflect on the contents of one’s own and other’s minds.
Introduction
Authors: Rolls Edmund T
Published: November 2023

What motivates us to work for particular rewards such as food when we are hungry, or water when we are thirsty? How do these motivational control systems operate to ensure that we eat approximately the correct amount of food to maintain our body weight or to replenish our thirst? What factors account for the over-eating and obesity which some humans show? The issues of what motivation is, and how it is controlled, are introduced in this chapter.
Pharmacology and neurochemistry of reward, and neural output systems for reward
Authors: Rolls Edmund T
Published: November 2023

It is well established that pharmacological manipulations of the catecholamine transmitters in the brain (dopamine and noradrenaline) alter self-stimulation rate (see Rolls 1975). For example, amphetamine, which enhances the release of dopamine and noradrenaline from axon terminals at synapses, increases hypothalamic self-stimulation rate. Drugs which reduce catecholamine levels (e.g. a-methyl-p-tyrosine) or which block catecholamine receptors (e.g. the ‘neuroleptic’ or ‘anti-psychotic’ drugs chlorpromazine, haloperidol, and spiroperidol) reduce self-stimulation rates. These catecholamine systems have been teased apart, and it is now clear that dopamine and not noradrenaline is involved in brain-stimulation reward (Section 6.2), but that dopamine is involved in brain-stimulation reward at only some sites (Section 6.3.1).
When Food Kills
Authors: Pennington T Hugh
Published: November 2023

The 'food scare' concept took on new meaning in 1996, which opened with variant CJD emerging as the human form of BSE, and closed with Britain's worst E.coli O157 outbreak in central Scotland. As people died, so did trust in government and science. This book tells the story of these events, what led up to them, and what has happened since. It breaks new ground by dissecting these tragedies alongside catastrophes like Aberfan, Piper Alpha, Chernobyl, and the worst ever railway accidents in Ireland and Britain (Armagh and Quintinshill), as well as classical outbreaks of botulism, typhoid, E.coli O157 and Salmonella food poisoning. Britain's ability to win Nobel prizes marches with a propensity to have disasters. The book explains why, demonstrating failures in policy making, failures in the application of science, and failing inspectorates. A unique feature of this book is its breadth since it covers history, politics and law as well as science. It also makes some fascinating connections, like those between 1930's nuclear physics, E.coli, and molecular biology, and the links between manslaughter in 19th century mental hospitals, syphilis, the Nobel Prize, and the prospects for successfully treating variant CJD. Royal murderers, vaccine research in Auschwitz and Buchenwald, and the race to develop the atom bomb appear as well. For the general reader its non-technical but authoritative account of the science behind these tragedies, its critical appraisal of how the government responded to them, its coverage of public inquiries and its analysis of risk will be informative and stimulating. Scientists will find its approach to the prion theory and the origins of BSE challenging and controversial. Policy makers will find not only diagnoses of what went wrong in the past, but remedies ror the future.
Adaptive FEM
Authors: Ram-Mohan L Ramdas
Published: November 2023

The discretization of the physical region and the representation of the wave function by piecewise polynomials generate errors both of which are intrinsic to the finite element procedure. Since its inception, it has been recognized that a successful application of the finite element method (FEM) requires estimating these errors and developing approaches to minimize them. In Chapters 1-3, it was shown that the FEM is a variational method in which better results can be obtained by the use of more elements and also through the use of higher order interpolation functions. However, no attempt was made to optimize the methods so as to provide a systematic approach for improving the results. We had implicitly assumed that the refinements in the FEM lead to convergence towards the exact results. In this chapter, we provide error estimates for the finite element solutions, derive convergence properties of the FEM, and develop schemes for automating the optimization procedure. There are several approaches to improving results obtained from the FEM, and here we will describe their essentials.
Applications in atomic physics
Authors: Ram-Mohan L Ramdas
Published: November 2023

An externally applied perturbation can provide information about the structure of energy levels in a quantum mechanical system. The investigation of the effect of an external magnetic field on the energy levels of the hydrogen atom, the simplest of atoms, has fascinated each generation of theoretical physicists in the last century. There is a long history in the literature of attempts at solving this problem by perturbative and variational methods.-s The problem is of such interest because of its relevance to astronomy and astrophysics, atomic physics, solid state spectroscopy, and the more recent exploration of quantum chaos exhibited by hydrogenic states with large Rydberg number n.
Quantum wires
Authors: Ram-Mohan L Ramdas
Published: November 2023

The ability to confine electrons spatially in a controlled way in layered semiconductor hetero structures has led to the observation of remarkable new optical and transport properties in such structures. Consequences of 1 D confinement in planar layered structures and the resultant quantized energy levels have been explored in great detail over the past two decades. In 1980, Sakaki considered theoretically the consequences of growing hetero structures which would confine electrons in two dimensions, the 2D quantum well or the quantum well wire (QWW). Since then, control over growth at an atomic level has allowed the construction of such hetero structures. As in 1D confinement, the principal effect is to profoundly change the energy spectra of electrons which in turn influence the optical and transport properties of the composite material.
The boundary element method
Authors: Ram-Mohan L Ramdas
Published: November 2023

The boundary element method (BEM) is based on an integral equation formulation for the solution of differential equations. As we have seen in the context of the finite element method (FEM), analytical methods become cumbersome when the geometrical shape of the physical domain is complex or when the boundary conditions (BCs) for the physical property being calculated are complicated. If there are inhomogeneous terms in the differential equation, they lead to a "particular integral" which is difficult to evaluate in a direct analytical manner. In general, inhomogeneous terms in the differential equation are treated by the method of Green’s function. A somewhat lengthy, but self-contained, exposition in Appendix C introduces the essential ideas of the Green’s function technique. We show below that by using Green’s theorem of vector calculus we can convert the differential equation under consideration into an integral equation on the boundary of the physical region. The discretization of the boundary integral leads to self-consistency conditions for the solution at the boundary. Once the solution at the boundary is obtained, the construction of the solution in the interior region proceeds in a straightforward manner. Thus the BEM employs the discretization of only the boundary, and not the interior of the physical region. This is a distinct advantage over the FEM, in which the entire physical region is discretized, which in turn leads to fairly large global matrices. The "reduction in dimensionality" associated with the BEM gives rise to global matrices of much fewer dimensions.
Public health infrastructure and knowledge
Authors: Powles John , Comim Flavia
Published: November 2023

One of the most striking features of mortality decline during the twentieth century was its decreasing dependence on national income levels. As the century progressed, populations were able to attain ever-higher life expectancy at given levels of real income, gaining from “shifting the curve” relating income to life expectancy, rather than from “moving along the curve” (World Bank 1993, p. 34).
Global public goods for health: From theory to policy
Authors: Smith Richard D , Beaglehole Robert , Woodward, David , Drager Nick
Published: November 2023

As indicated in the foreword to this book, writing on global public goods (GPGs) has been mostly broad-based and multi sectoral; consideration of GPGs with specific respect to health has been brief and largely focused on medical technologies. This book brings together a series of papers exploring whether, and how best, the GPG concept may be used to advance global health, and especially the health of poor populations and countries, in a broader sense.
Quantum Transport and Chaos in Billiards
Authors: Nakamura Katsuhiro , Harayama Takahisa
Published: November 2023

Let us start with a planar quantum dot with 2-d lead wires as shown in Fig. 2.1. How does quantum mechanics treat the quantum phenomenon of electrical conductance through the dot? The attached lead wires are rectangular and semi-infinite with their width finite in the direction perpendicular (transverse) to the leads. Due to the transverse confinement, the eigenstates of an electron in the leads are finite in number and their eigenenergies are discrete.
Motion of a Billiard Ball
Authors: Nakamura Katsuhiro , Harayama Takahisa
Published: November 2023

The billiard ball here means a point particle with no internal degrees of freedom like the spinning motion. We assume that each collision of a particle with the walls is perfectly elastic and is accompanied by no energy dissipation. From this it follows that whenever a particle collides with the walls, it obeys the law of reflection that the angle of incidence is equal to that of reflection. Suppose a reference particle starts under a given initial condition (for its position and direction of velocity vector), while its partner starts with the same magnitude of velocity vector under a slightly different initial condition.
Introduction to Monte-Carlo Methods for Transport and Diffusion Equations
Authors: Lapeyre B , Pardoux É , Sentis R
Published: November 2023

Monte-Carlo methods is the generic term given to numerical methods that use sampling of random numbers. This text is aimed at graduate students in mathematics, physics, engineering, economics, finance, and the biosciences that are interested in using Monte-Carlo methods for the resolution of partial differential equations, transport equations, the Boltzmann equation and the parabolic equations of diffusion. It includes applied examples, particularly in mathematical finance, along with discussion of the limits of the methods and description of specific techniques used in practice for each example. This is the sixth volume in the Oxford Texts in Applied and Engineering Mathematics series, which includes texts based on taught courses that explain the mathematical or computational techniques required for the resolution of fundamental applied problems, from the undergraduate through to the graduate level. Other books in the series include: Jordan & Smith: Nonlinear Ordinary Differential Equations: An introduction to Dynamical Systems; Sobey: Introduction to Interactive Boundary Layer Theory; Scott: Nonlinear Science: Emergence and Dynamics of Coherent Structures; Tayler: Mathematical Models in Applied Mechanics; Ram-Mohan: Finite Element and Boundary Element Applications in Quantum Mechanics; Elishakoff and Ren: Finite Element Methods for Structures with Large Stochastic Variations.
The Monte-Carlo method for diffusion equations
Authors: Lapeyre B , Pardoux É , Sentis R
Published: November 2023

In this chapter, we shall first give the probabilistic interpretation of the heat equation due to Brownian motion. This plays a role comparable to characteristic curves that allows us to express the solution of an advection equation of the form:

b being a function of x. We then show that the results obtained for the Laplacian can be generalized to second-order operators with variable coefficients, the Brownian motion being, in this case, replaced by a diffusion process. We then describe in broad outline the Monte-Carlo algorithms that are used to solve parabolic and elliptic equations numerically.
Hamiltonian Dynamics
Authors: Zaslavsky George M
Published: November 2023

A wide class of physical phenomena can be described by Hamiltonian equations. This class includes particles, fields, classical and quantum objects, and it makes up a significant part of our knowledge of the basics of dynamics in nature. Hamiltonian dynamics is very different from, for example, dissipative dynamics, and its analysis uses specific tools that cannot be applied in other cases. Discovery of chaotic dynamics is a result of discovering new features in Hamiltonian dynamics and new types of solutions of the dynamical equations.
Physical Models of Chaos
Authors: Zaslavsky George M
Published: November 2023

All physical classical models are described by differential or integro-differential equations and the discrete time systems can be considered as simplified versions of these equations.
Weak Chaos and Symmetry
Authors: Zaslavsky George M
Published: November 2023

Chaotic dynamics per se means a strong instability of trajectories and their exponential separation from each other. Nevertheless, the area occupied by chaotic trajectories can be very small, even exponentially small, comparing to the whole phase space.