bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observed Properties Of Liquid 4He Liquid 4
Authors: Glyde Henry R 
Published: November 2023

Abstract
Liquid 4He is the most accessible Bose fluid in nature. Its structure and excitations have therefore been widely investigated using neutron scattering and other techniques, the topic of this chapter. Early measurements are touched on in §9.5 and are superbly reviewed by Woods (1965).A next generation of experiments followed. These measurements, including light scattering and sound transmission measurements, mapped out the basic static and dynamic properties of liquid 4He. This data and its interpretation are authoritatively reviewed by Woods and Cowley (1973). This review, the paper by Cowley and Woods (1971), and the subsequent data by Dietrich et al. (1972) and Graf et al. (1974) provide a complete account of the field up to the mid 1970s. These papers set the stage for the present chapter and are highly recommended.
Excitations In Liquid 3He
Authors: Glyde Henry R 
Published: November 2023

Abstract
In this and the following five chapters we discuss the study of excitations in normal liquid 3He by neutron scattering. Liquid 3He is the prototype, monatomic Fermi liquid in nature. Understanding its fascinating properties is therefore a fundamental issue in quantum physics. This understanding can also be applied to more complicated Fermi liquids such as electrons in metals, superconductivity, and to protons and neutrons in nuclei.
Detectors and spectrometers of UCN
Authors: Ignatovich V K , Pontecorvo G B 
Published: November 2023

Abstract
Detectors of UCN are based on the same principle as conventional neutron counters, namely they contain a substance called the radiator, the nuclei of which absorb neutrons and subsequently decay, emitting charged particles. The charged particles are then registered either by their tracks (track detectors), or by light flashes (scintillation detectors), or with the aid of electric discharges (proportional counters and solid-state detectors).
Why robots
Authors: Holland Owen , McFarland David 
Published: November 2023

Abstract
In this chapter we address the more general questions relating to the use of robots in biological research. Much of the material in this chapter comes from discussions arising at the Artificial Ethology Workshop in 1998.
During the discussions we attempted to answer the following questions:
Although there is clearly a degree of overlap between some of these questions, they provide a useful way of structuring a discussion of the value of robots to biology.
Differentiable Manifolds
Authors: Wasserman Robert H 
Published: November 2023

Abstract
At the beginning of Chapter 7 we mentioned that for the description of physical phenomena we have to generalize the concept of maps between cartesian spaces to those between more general domains and image spaces. We want to keep the domain as general as possible; i.e., with as little structure as possible. This is the perspective that motivates the study of sets on which local coordinates are defined. After general definitions, examples, and a brief discussion of mappings we impose the structures of Sections 7.2 and 7.3 on manifolds.
Mechanics
Authors: Wasserman Robert H 
Published: November 2023

Abstract
Our exposition of geometry in Chapters 15, 16, and 17 consisted of starting with a manifold and superimposing a symmetric tensor field of type (0, 2), or prescribing a covariant derivative for vector fields, and then studying the properties of such abstract structures. A motivation for each generalization and abstraction is that it includes as a special case the classical well-established geometry with which we are familiar.
Symplectic Manifolds
Authors: McDuff Dusa , Salamon Dietmar 
Published: November 2023

Abstract
This is a foundational chapter, and everything in it (except perhaps Section 3.4 on contact structures) is needed to understand later chapters. The first section contains elementary definitions and first examples of symplectic manifolds. The second section is devoted to Darboux’s theorem. Some situations are flexible and there are no nontrivial invariants, while other situations are rigid. In this chapter we deal with ‘soft’ phenomena, the fact that in symplectic geometry there are no local invariants. The classical formulation of this principle is known as Darboux’s theorem: all symplectic forms are locally diffeomorphic. However there are many other related results, such as Moser’s stability theorem and various versions of the symplectic neighbourhood theorem.
Ion excitation: ion beam spectrochemical analysis (IBSCA) and glow discharge optical spectroscopy (GDOS)
Authors: Riviere J C 
Published: November 2023

Abstract
Although these two techniques depend on rather different physical mechanisms, they are discussed together here since the one thing that they have uniquely in common is identification of sputtered species by spectroscopic analysis of light in the visible region. They bear approximately the same relationship to each other as do SSIMS and GDMS, to be the subjects of following chapters.
Lattice dynamics
Authors: Dobbs E R 
Published: November 2023

Abstract
In this chapter we outline the development of a theory of solid helium as a quantum solid, that is, one in which the zero point energy Ezis roughly equal to the static potential energy U0, in contrast to classical solids where Ez≪ U0First, we discuss the important differences between the environment of an atom in a classical solid like argon with those of an helium atom in a quantum solid, although in both cases their interatomic pair potentials can be approximated by the well-known Lennard-Jones (12, 6) potential.
Low-dimensional structures
Authors: Dobbs E R 
Published: November 2023

Abstract
Studies of the adsorption of He on a variety of surfaces, but especially on graphite, have provided a wealth of information on the behaviour of two-dimensional (2D) quantum solids and their interactions with substrates. In this chapter, the establishment of a phase diagram for a monolayer of He from heat capacity measurements is followed by accounts of recent studies of the magnetic and thermal properties of the first, second, and higher layers of He on graphite. Finally, some interactions of 2D He with other substrates are discussed.
The historical and scientific perspective
Authors: White Guy K , Meeson Philip J 
Published: November 2023

Abstract
It is said that survival sharpens the mind. Many low-temperature techniques evolved from this beginning. The eskimos found that a finely divided air-hair mixture provided very effective thermal insulation in the Arctic winter. Likewise the desert arab found multilayers—fabric and airspace—helped him survive the summer. We understand there is also an old Arab saying that ‘light is heat’—their homes provided good radiation protection by having no unshuttered windows! The earliest cooling systems were probably evaporative, letting water slowly seep through ceramics and evaporate in hot dry surroundings. To this day a canvas water bag carried on a car bumper bar or around a camel’s neck is a boon to the summer traveller in hotter climates. A larger version used in the Australian hinterland for a hundred years or more, was a box or whole room covered in hessian cloth and continually kept moist by a capillary-drip system to preserve food. This was locally called the Coolgardie safe by the early gold miners in an arid part of Western Australia. In other climates like Europe or northern America where winters are extreme, the inhabitants cut and stored the winter ice in underground caves or huts which were well insulated with earth and straw or sawdust.
Heat transfer
Authors: White Guy K , Meeson Philip J 
Published: November 2023

Abstract
A determination of the physical properties of materials at temperatures which are different from the surrounding temperature requires thermal isolation of the material from its surroundings; the degree of isolation must be sufficient to meet the demands of temperature control, temperature measurement and, in the case of low-temperature research, the available refrigerating capacity of the coolant. In general, heat may be transferred by conduction, convection, and radiation. In most low-temperature applications, convection is not significant because of the partial evacuation of gas from the interior of the cryostat. Effective heat transfer takes place by conduction through the residual low-pressure gas, conduction through the solids that interconnect the various parts of the cryostat, and by radiation. In addition such factors as Joule heating in electrical leads, eddy current heating, mechanical vibration, absorption or desorption of gases may contribute to the heat transfer.
Temperature control
Authors: White Guy K , Meeson Philip J 
Published: November 2023

Abstract
It is almost always the case in the course of experimentation at low temperatures that the experimenter not only wishes to know the temperature of the sample whose properties are to be measured but also wishes to achieve a particular sample temperature and wishes to hold that desired temperature for some useful length of time. The experimenter will also want to know that the required temperature has been obtained to within some specified accuracy for the duration of any particular measurement. Generally experiments need to be performed over a range of temperatures in order to determine, for instance, whether a sample has some particular power law or exponential dependence of its properties on temperature. Information such as this is often particularly revealing of the physics of the sample. For example, it may be possible to design an experiment to measure the thermal conductivity of some sample in which the absolute value of the thermal conductivity is not well determined because of some unknown factor, such as an irregularly shaped sample. Under such circumstances it is still possible to determine the temperature dependence of the thermal conductivity to a rather high degree of accuracy, because the unknown parameters are precisely constant and may be factored out. Conversely, it is important in such circumstances to make measurements over a sufficiently large range of temperature (given some finite indeterminacy or error bar in any one measurement at any one temperature) to ascertain any supposed power law with sufficient confidence. Finally, we do not wish to see any instability in the temperature being the major contributor to uncertainties or errors in the final value obtained from a measurement.
The evolution of gene regulation: approaches and implications
Authors: Bergman Casey M , Patel Nipam H 
Published: November 2023

Abstract
Since the earliest days of molecular biology, there has been increasing interest in understanding the role of transcriptional regulation in the morphological evolution of higher organisms. This trend owes its origin to the pioneering insight from studies of the lac operon which demonstrated that modern genomes contain DNA sequences devoted solely to the regulation of other genes (Jacob and Monod 1961). These sequences were shown to be closely linked in “cis” to the gene(s) under transcriptional regulation and function as the targets of “trans” acting factors. These cis-regulatory sequences were immediately regarded as being potential targets of functional change exerted by evolutionary forces such as mutation, selection and genetic drift.
Mass extinctions and evolutionary radiations
Authors: Erwin Douglas H 
Published: November 2023

Abstract
Mass extinctions are a critical driving force for evolutionary change. Whether the patterns of extinction are random or selective, they prune the tree of life and the subsequent evolutionary rebounds provide an opportunity for previously minor clades to become dominant, for dramatic reorganizations of ecosystems, and for the appearance of significant evolutionary innovations. Not all mass extinctions trigger such reorganizations, however. Some have relatively little long-term influence on the course of evolution. Yet, however much we may regret the current, human-driven loss of biodiversity, the fossil record clearly demonstrates the evolutionary impact of mass extinctions.
Could there be a Darwinian account of human creativity?
Authors: Dennett Daniel C 
Published: November 2023

Abstract
Weaverbirds create intricate nests; sculptors and other artists and artisans also create intricate, ingenious constructions out of similar materials. The products may look similar, and outwardly the creative processes that create those processes may look similar, but there are surely large and important differences between them. What are they, and how important are they? The weaverbird nestmaking is “instinctual,” and “controlled by the genes” some would say, but we know that this is a crude approximation of a more interesting truth, involving an intricate interplay between genetic variation, long-term developmental and environmental interaction and short-term environmental variation—in opportunities and materials accessible at the time of nest building.
Statistical mechanics and thermodynamics
Authors: Yeomans J M 
Published: November 2023

Abstract
This chapter moves through the large number of reminders and definitions necessary to arrive at the point where we can introduce the idea of universality, one of the most striking features of the theory of critical phenomena and a major justification for the interest in model systems. The first step is to summarize the statistical mechanics used throughout the book. Assuming that this is familiar material the main aim will be to gather together the relevant formulae in a form suitable for reference.
Mean-field theories
Authors: Yeomans J M 
Published: November 2023

Abstract
Very few statistical mechanical models have been solved exactly. In three dimensions not even the nearest neighbour spin-1/2 Ising model is tractable. Therefore it is necessary to resort to approximation methods. One of the most widely used of these is mean-field theory. A systematic way of deriving the mean-field theory for a given microscopic Hamiltonian is to start from the Bogoliubov inequality This gives the best possible approximation to the true free energy for a given choice of Ho because the inequality (4.1) insists that the meanfield free energy cannot fall below the true free energy. (This is analogous to the variational principle in quantum mechanics.) The usual choice for Ho is a free Hamiltonian -one with no interactions-as this enables explicit calculation of the right-hand side of (4.1).
Monte Carlo simulations
Authors: Yeomans J M 
Published: November 2023

Abstract
It could be argued that current physics research can be divided into three areas-theoretical, experimental, and computational. umerical approaches, in which systems are mimicked as accurately as possible using a computer or in which computer models arc set up to provide well-behaved experimental systems are increasingly providing a bridge between theory and experiment. The limitations on what can be clone are set by the computational resources available.
Theoretical Frameworks Relevant for GR Studies
Authors: Harakeh M N , van der Woude A 
Published: November 2023

Abstract
In the first chapter the occurrence of GRs in nuclei was discussed. These can be understood as collective excitations of a quantum many-body system, in this case the nucleus. GRs can be described as the response of the nucleus to a weak external field, such that a linear approximation can be applied. This field can be decomposed into various multipoles and the response can thus be viewed as the sum of the various contributions of the multipole GRs. The definition of GRs stems from the observation of the dominant GR structure in photo-absorption spectra, now known as the isovector giant dipole resonance (IVGDR). However, GRs of various multipolarities are common features of excitation of the nucleus. They occur systematically for all nuclei across the mass table, and their macroscopic properties such as excitation energy and width vary smoothly as a function of the atomic mass number A. Furthermore, they exhaust a large fraction of the transition strengths (sum rules) connected with the multipole transition operators of the external fields responsible for their excitation.
Electric Charge of the Neutron
Authors: Alexandrov Yu. A , Drozdova T F 
Published: November 2023

Abstract
The question of the existence of the electric charge of the neutron is closely connected with the general question: why are the charges of all elementary particles equal to ± Q e, where Q e is the charge of the electron, or to zero?† The neutron is conventionally assumed to be neutral, but it is not theoretically forbidden for it to have a small electric charge, so an experiment on a search for it might be of extreme interest.In the modern theory of elementary particles the laws of conservation, for example of electric, baryonic, and leptonic charges, play an important role. Their validity has been tested experimentally to great precision, and no case of their violation has been observed to date. They are believed to be ‘absolute’, that is to hold for all three types of elementary particle interactions (strong, electromagnetic, and weak). Together with the laws of conservation of energy, momentum, and angular momentum they govern the interaction of elementary particles.
Electromagnetic Structure of the Neutron
Authors: Alexandrov Yu. A , Drozdova T F 
Published: November 2023

Abstract
The urgency to develop ideas of the structure of objects comes from the natural desire to understand the infinite variety and complexity of the visible world as the outcome of an enormous number of possibilities available to a small number of fundamental entities subjected to fundamental laws of behaviour.The atomistic character of the macro world was first proposed by the ancient philosophical school, but physical phenomena and the mechanical, thermal, or other properties of gross matter were only well understood in terms of the atomistic concept after the creation of kinetic theory and statistical mechanics. In the late nineteenth and early twentieth centuries it became clear that atoms themselves were not irreducible but consisted of even smaller objects, that is electrons and nuclei. From this viewpoint one can easily explain the whole variety of phenomena and the dynamics of processes going in an atom: quantized energy levels, scattering of charged and neutral particles, etc. It is correct to some extent to speak about the neutron-proton structure of the nucleus. However, this structure has a more dynamical character than atomic structure. Finally, quite a new situation is encountered in the consideration of the structure of elementary particles: whereas the atom and in large measure the nucleus itself could be considered to be composed of electrons, protons, and neutrons as essentially permanent constituents, for the internal structure of elementary particles one is forced to admit the existence of unobservable virtual particles created from a certain period of time defined by the Heisenberg uncertainty principle and existing only to carry a specific interaction. This radically new approach to the problem has appeared possible only with the development of quantum mechanics.
Neutron-Neutron Scattering
Authors: Alexandrov Yu. A , Drozdova T F 
Published: November 2023

Abstract
The experimental determination of the neutron-neutron scattering length is of interest from the point of view of both the study of nucleon-nucleon interactions and the verification of the hypothesis of isotopic invariance of strong interactions at low energies. Since nuclear reactors at present produce a maximum neutron density of no more than 1011 cm−3, direct measurements of neutron-neutron scattering are still a matter of discussion. All the information currently available on the interaction between two neutrons has been obtained from indirect measurements that are reduced to a study of the effect of the neutron-neutron interaction on the spectrum from the reaction resulting in the formation of three particles. Before considering such experiments let us discuss some aspects of the hypothesis of charge independence of nuclear forces.
The Antineutron
Authors: Alexandrov Yu. A , Drozdova T F 
Published: November 2023

Abstract
An antiparticle was first identified in cosmic rays by Anderson in 1932. It was a positron. However, a quarter of a century was to pass before it was discovered that the Bevatron, which accelerated protons to 6 GeV, produced antiprotons (1955) and antineutrons (1956).Antineutrons were found by Cork et al. [391]
Basic characteristics of semiconductors
Authors: Balkanski M , Wallis R F 
Published: November 2023

Abstract
The history of semiconductors dates back to the nineteenth century. The decrease in resistance of silver sulfide with increasing temperature was noticed by Michael Faraday (1833). Selenium was found to be photo-conducting by W. Smith (1873), and the rectifying properties of lead sulfide were observed by F. Braun (1874). During World War II silicon found application as a rectifier in radar. By far the most important event, however, was the discovery of transistor action in germanium by J. Bardeen and W. H. Brattain in 1948, which ushered in the explosive development of high technology based on semiconductors that continues to the present day.
Electronic energy bands: basic theory
Authors: Balkanski M , Wallis R F 
Published: November 2023

Abstract
Although applications such as rectifiers that we now associate with semi-conductors had been known as far back as the nineteenth century, it was not until after the development of quantum mechanics in the late 1920s that the physical basis for these properties became understood. A. H. Wilson showed in 1931 how the electronic band theory of crystals developed by F. Bloch can be applied to the understanding of semiconductors. Properties such as the negative temperature coefficient of electrical resistivity follow naturally from Wilson’s theory. The key ingredients are the Bloch states which are the eigenstates of an electron moving in the periodic potential of a crystal. The energies of the Bloch states cannot take on all possible values, but are restricted to certain allowed regions or bands separated from one another by forbidden regions or band gaps as shown in Fig. 2.1. The allowed energy bands are analogous to the pass bands of an electric transmission line and are characteristic of any wave propagating through a periodic structure (Brillouin 1953).
Semiconductor statistics
Authors: Balkanski M , Wallis R F 
Published: November 2023

Abstract
In order to calculate properties such as electrical conductivity, it is necessary to know the concentration of electrons in the conduction band and holes in the valence band. These current carriers can arise by thermal or optical excitation of electrons from the valence band to the conduction band, by excitation of carriers from impurity states, or by injection from an outside source. In this chapter we focus on carrier concentrations in a semiconductor in thermal equilibrium.
P-N iunctions in semiconductors
Authors: Balkanski M , Wallis R F 
Published: November 2023

Abstract
We have seen in Chapter 5 that impurities of different types can be introduced into bulk intrinsic semiconductors. If the impurity is the source of free charge carriers that are negatively charged electrons, the material is designated n-type, whereas if the impurity is the source of positively charged holes, the material is designated p-type. In n-type material the principal impurities are donors, and the majority carriers are conduction electrons arising primarily from the ionization of donor atoms. In p-type material, the principal impurities are acceptors, and the majority carriers are holes created by the transfer of electrons from the valence band to acceptor atoms leaving positively charged holes in the valence band. In both types of material at nonzero temperature, conduction electrons and holes arising from the excitation of electrons across the energy gap are also present. The thermally excited holes in n-type material and conduction electrons in p-type material are called minority carriers.