bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spin echoes and thermodynamics
Authors: Waugh J S 
Published: November 2023

Abstract
The spin echo [1] is still striking to those who see it for the first time, as it probably was to Hahn. A nuclear magnetization, having disappeared in a free induction decay (FID), spontaneously reappears as a giant fluctuation. While the phenomenon is easily understood from a mechanical point of view, it seems to verge on a violation of the second law of thermodynamics. It is this problem, about which Hahn [2] and others [3] have written, that we approach here again from what is at least partly a fresh perspective. Our point of view will be that echoesdo violate the second law. After having defended this case we will discuss briefly how the problem can be avoided by appropriate statement of purely macroscopic thermodynamic principles.
Spin choreography
Authors: Freeman R 
Published: November 2023

Abstract
Very soon after the initial discovery of nuclear magnetic resonance, E. L. Hahn performed an experiment that, in conceptual originality and elegance, transcended all that had preceded it-the spin echo experiment [1]. Here was an idea to inspire the young scientists reading about NMR for the first time. Not only could oneworkwith these strange new entities called spins, but alsomanipulatethem like a conjuror with a pack of cards. In its original form, experiment was conceptually easier to follow, resembling the opening and closing of a ‘fan’ of vectors confined to the transverse(x-y)plane of the rotating frame. Note that the description of the conventional continuous wave NMR experiments of the time scarcely required this level of sophistication, relying on the steady state solutions of the Bloch equations. To understand spin echoes, one was forced to come to grips with homogeneous and inhomogeneous line broadening, transformation into the rotating frame of reference, and the concept of ‘spin isochromats’. This was a term coined by Abragam [3]. The sample is considered to be made up of a mosaic of volume elements, each small enough that the variation of the applied field intensity across that element could be neglected, but with neighbouring elements in slightly different applied fields due to the spatial inhomogeneity. Each element has a nuclear magnetization with a characteristic precession frequency; this is an isochromat. The total sample magnetization is the resultant of all these isochromatic magnetization vectors. Because the isochromats have different intrinsic frequencies this resultant can change as individual isochromats fan out or come back into alignment. This has proved a valuable idea for describing spin echo experiments.
Deuteron multiple echoes
Authors: Conradi M S , Fedders P A , Norberg R E 
Published: November 2023

Abstract
Deuteron multiple echoes have been observed for HD and o - D2molecules trapped in the presence of large static electric field gradients. The multiple echoes are of the variety described by Solomon [ 1], Butterworth [2], Mehring and Kanert [ 3] , and Boden [4,5] and are resolved from the 2r solid echo because of the presence of a relatively large intramolecular dipolar interaction colinear with the intramolecular quadrupole coupling. The deuteron multiple echoes are uniquely molecule-specific and have been observed for HD and o - D2molecules trapped in amorphous silicon [5-10] and germanium [ 11] as well as adsorbed on MgO surfaces [12] . The occurrence of the multiple echoes, and their manipulation by proton double resonance, provides a nice example of spin dynamics in exceedingly simple systems and a unique opportunity to measure the average field gradient at a surface.
Imaging by nuclear magnetic resonance*
Authors: Mansfield P 
Published: November 2023

Abstract
The subject of nuclear magnetic resonance (NMR) is well known to physicists, and especially chemists and biologists, as an analytical technique for the study of inter- and intra-molecular interactions [1,2]. For those unfamiliar with recent developments, therefore, it is perhaps surprising to learn that NMR techniques have over the last 10 years or so been adapted and refined by a number of groups, thus making possible, through the study of externally imposed macroscopic spin interactions, the observation and measurement of morphology of macroscopic objects. The aim in traditional NMR experiments is to observe the specimen in as uniform a magnetic field as possible (high resolution). In this case all magnetically active spins within the sample resonate at approximately the same Larmor resonance angular frequencyw,given byw=‘YB,where‘Yis a constant for a particular spin species and is called the gyromagnetic ratio, andB is the magnitude of the applied static magnetic field B. The small deviations in frequency measured in such high resolution experiments are minor perturbations of the spin energy levels which come about through electronic screening of the nucleus (chemical shift), and/or indirect nuclear (hyperfine) interactions via the overlap of electronic shells of neighbouring nuclei. In a solid there is additionally the nuclear dipole-dipole interaction which usually dominates in size over the previously mentioned interactions by an order of magnitude or so. For protons, the chemical shift and hyperfine interactions are usually very small indeed. In a medium resolution magnet, therefore, the proton resonance absorption line shape for many common materials is broadened or smeared into a symmetric structureless line which completely masks the smaller interactions. This is the case for most of the mobile protons in biological tissue. However, at high enough fields, there is a measurable chemical shift difference between water and fat.
Clinical imaging
Authors: Crooks L E , Rothschild P 
Published: November 2023

Abstract
The advent of diagnostic magnetic resonance imaging (MRI) appears to have occurred in a startlingly short time, but what was actually abrupt is only the perception by physicians of this technology’s impact on the way diagnoses are performed. The theoretical basis and demonstration of NMR is a development of the late 1940s and, in condensed matter, resulted in the 1952 Noble prize for physics to Edward Purcell and Felix Bloch. The understanding of the nucleus (which led to the conception of NMR), discovery of superconductivity (an important component of magnets used for MRI), and basic work leading to present computers were all developments of the early 1900s incorporated together in the 1960s. Then NMR systems combined these three items for spectroscopy investigations with ever improving performance. Clinical MRI also owes much to the development of computed tomography (CT): first, it established the precedent that an expensive device could have a place in routine diagnosis; second, most, if not all, of the companies that build CT scanners found themselves with unused plant and personnel capacity when regulation slowed the growth of CT below their expectations. With the advent of MRI, some companies saw a natural outlet for their excess capacity. In addition, the companies that fared poorly in CT hoped for a chance to make up their losses by aggressively pursuing MR, while successful CT manufacturers felt the need to go into MR to protect their market positions. These factors resulted in unprecedented expenditures for an untested product by traditionally conservative companies that typically allow the marketplace to be tested by small entrants, which they then try to buy or displace.
Quantum beat echoes
Authors: Hashi T , Fukuda Y , Tanigawa M 
Published: November 2023

Abstract
The spin echo [1 ] discovered by Erwin Hahn in 1950 is one of the most sophisticated phenomena in physics. It demonstrates the fact that the decay of coherence due to the inhomogeneous broadening can be recovered by an ingenious ‘effective time reversal’ technique. Since then, the research on coherent transients has been developed in the field of pulsed magnetic resonance [2]. The advent of the laser stimulated the studies in the optical region. Optical analogues of most of the coherent transients in magnetic resonance have been realized [ 3] except for those in solids, whose mechanisms are based on the spin temperature hypothesis [4] . Thus coherent interactions between radiation and atoms have been extensively studied and the techniques developed have been effectively used in a variety of fields. In the studies of so-called two-level problems the coherence is generated by a direct excitation of the relevant transitions by radiofrequency (r.f.), microwave, or laser fields.
General constraints on naked singularity formation
Authors: Joshi Pankaj S 
Published: November 2023

Abstract
In the previous chapter, we showed that strong curvature naked singularities arise in a variety of situations involving dust, perfect fluid, and radiation collapse for self-similar as well as non-self-similar space-times. These are dynamical situations representing a gravitational collapse scenario and the matter content of the space-time is reasonable in that the energy conditions implying the positivity of energy are satisfied and widely used equations of state arc obeyed. Hence, these collapse scenarios must be taken into account for any possible formulation of the cosmic censorship hypothesis. In fact, in order to arrive at any provable formulation of the censorship hypothesis, or otherwise to assess the reasonability of these examples, it appears necessary to examine possible constraints which must be obeyed by naked singularities occurring in the general theory of relativity.
Global upper limits in cosmology
Authors: Joshi Pankaj S 
Published: November 2023

Abstract
In this chapter, we apply the global concepts developed in Chapters 4 and 5 to deduce certain general upper limits in cosmology. Specifically, our aim is to allow for perturbations from the assumed homogeneity of the universe and to deduce in this general scenario the upper bounds on the age of the universe as well as limits on the elementary particle masses which were produced copiously during the early phases of the universe and which may be filling the universe today.
phase transitions and criticality
Authors: Dixon J M , Tuszynski J A , Clarkson P A 
Published: November 2023

Abstract
I would claim that the most important advances in this area (condensed matter physics) come about by the emergence of qualitatively new concepts at the intermediate or macroscopic levels-concepts which, one hopes, will be compatible with one’s information about the microscopic constituents, but which are in no sense logically dependent on it. These new concepts . . . have in common. . . that they provide a new way of classifying a seemingly intractable mass of information of selecting the important variables from the innumerable possible variables which one can identify in a macroscopic system.
The method of coherent structures (MCS)
Authors: Dixon J M , Tuszynski J A , Clarkson P A 
Published: November 2023

Abstract
I disagree with most physicists at the present time just on this point [of removing divergent diagrams). I cannot tolerate departing from the standard rules of mathematics. Of course, the proper inference from this work is that the basic equations are not right. There must be some drastic change introduced into them so that no infinities occur in the theory at all and so that we can carry out the solution of the equations sensibly, according to ordinary rules and without being bothered by difficulties. This requirement will necessitate some really drastic changes: simple changes will not do, just because the Heisenberg equations of motion in the present theory are all so satisfactory. I feel that the change required will be just about as drastic as the passage from the Bohr orbit theory to the quantum mechanics.
Chaos and one-dimensional maps
Authors: Holton David , May* Robert M 
Published: November 2023

Abstract
In our everyday experience we frequently encounter processes which exhibit chaotic or apparently random behaviour: the constantly changing weather pattern, the flow of a turbulent stream, or the fluctuations in the population of a species. These are dramatic examples of systems which display complicated and seemingly indeterminate behaviour. However, these are precisely the kinds of systems which hold most fascination and which we wish most to be able to rationalize, to model, and, using estimates based on the model, to predict future behaviour. The traditional view of the complexity of nature is that there is little hope of unravelling the underlying reasons for randomness. The elements of cause and effect are believed to be so intricate and the interactions so complicated, appearing on so many spatial and temporal scales, that the net result is that the many influences act incoherently and statistically, to yield an unfathomable mess.
Models of chaos from natural selection
Authors: Holton David , May Robert M 
Published: November 2023

Abstract
In experimental philosophy we are able to look upon propositions obtained by general induction from phenomena as accurately or very nearly true ... till such time as other phenomena occur, by which time they may be accurate or liable to exceptions. The principles of general induction upon which Newton formulated the celestial mechanical equations of motion began the interpretation of dynamics in terms of mathematics. This early development spawned infinitesimal mathematics or calculus. A complete understanding of the solutions of these equations of motion, however, has remained out of reach.
Distinguishing chaos from noise
Authors: Holton David , May Robert M 
Published: November 2023

Abstract
A central theme to dynamical systems is the recognition that simple deterministic mechanisms can generate random-looking data. However, can random-looking data, derived from an experiment, be attributable to a simple deterministic mechanism? There are several sources of difficulty in attributing a random time series from a natural system to a deterministic source. The randomness may be a result of errors inherent in making the measurement, for example, in sampling errors in estimating sizes. Also, there may be fluctuations derived from unpredictable environmental changes; this is perhaps most insidious, since it suggests the system is strongly coupled to the environment and hence inherently of high dimension. Another difficulty could be that the system is intrinsically of high or infinite dimension with interactions on many temporal and spatial scales. This being the case, we can no longer hope for a low-dimensional dynamical description.
Ion Traps
Authors: Ghosh Pradip K 
Published: November 2023

Abstract
The author provides, in nine chapters, a compact and up-to-date coverage of the entire range of applications of the two most important ion traps: the Paul('radiofrequency') trap and the Penning('dc) trap. The book begins with full details of the ion confinement principles of both these traps; this is followed by a presentation of the basic experimental techniques, including details of a few actual traps. There is then a chapter on the methods of ion cooling, now an essential integral part of all trap-based experiments. The next four chapters provide a comprehensive coverage of applications in four major areas, broadly classified as: atomic physics, frequency standards, collision studies, and analytical mass spectrometry. The text is appended by a set of more than 600 fully titled chronologically arranged references which mirror the growth of the field as well as providing a comprehensive guide to original research papers. The text should be useful to students both at the senior undergraduate and beginning graduate level as a general reader for professionals in atomic physics, chemical physics, mass spectometry and related fields.
Ion Traps In Atomic Physics
Authors: Ghosh Pradip K 
Published: November 2023

Abstract
In this chapter we present applications of ion traps to: (i) determination of the g-value of an electron from electron spin resonance experiments on a single electron, (ii) observation of quantum jumps in a single trapped ion, (iii) an experimental test of the quantum Zeno effect, (iv) a precision test of the linearity of quantum mechanics, (v) a range of studies on one-component microplasmas, (vi) optical spectroscopy of molecular ions, (vii) precision mass measurement of stable isotopes, (viii) precision mass measurement of radioactive isotopes, (ix) trapping and precision mass measurement of antimatter, specifically of antiprotons, (x) lifetime measurement of neutron undergoing beta decay, and (xi) atomic physics of highly charged ions.
Biology
Authors: Kimsey Lynn S , Bohart Richard M 
Published: November 2023

Abstract
The biology of only a small percentage of chrysidid species has been investigated, and even these cases deal mostly with the identity of the host. All known chrysidids are parasites and their presence nearly always results in the death of the host. Therefore they fall into the categories of parasitoids or cleptoparasites. The latter name is appropriate when provisions by the adult host for its larva are ‘stolen’ and consumed. Bethylids, the sister-group of the chrysidids, are parasitic on moth and beetle larvae. Chrysidids may feed on both of these, but only in a secondary way.
Subfamily Amiseginae
Authors: Kimsey Lynn S , Bohart Richard M 
Published: November 2023

Abstract
The Amiseginae are small cryptic wasps, found low in vegetation or in leaf litter. They can be recognized by the five external abdominal segments in males and four in females, as well as the flat or concave face, slender mandibles, and needle-like ovipositor. These wasps are infrequently collected but this is more a reflection of collecting techniques than of actual abundance. The highest species diversity occurs between latitudes 30° north and 30° south. Amisegines are parasites of phasmatid walking stick eggs.
Subfamily Loboscelidiinae
Authors: Kimsey Lynn S , Bohart Richard M 
Published: November 2023

Abstract
These unusual and aberrant looking wasps are rarely collected and as a consequence are not well known. They can be recognized immediately by the oddly shaped head, antennae inserted high on the face, large tegulae, and abdomen with five external segments in males and four in females. Loboscelidiines occur in the Indoaustralian Region. The structure of the mandibles and ovipositor suggests that these wasps are also parasites of walking stick eggs.
Re-introducing birds: lessons to be learned for mammals
Authors: Ounsted M L 
Published: November 2023

Abstract
The criteria for bird re-introductions are likely to be similar to those for mammals. To date, though some bird re-introductions are considerd a useful conservation tool in the broadest sense, bird re-introduction has rarely been shown to have achieved its primary aim of re-establishing a self-sustaining population in the wild. With birds, the behavioural and anatomical implications of flight severely restrict the control and monitoring of individual re-introduced birds. The behavioural characteristics of species even within one taxonomic group vary greatly and limit the suitability of species for re-introduction. Eggs facilitate the artificial propagation of many species. Since eggs are easy to transport, hatched chicks may more easily acclimatize to new environments and the likelihood of disease transfer can be reduced.
Veterinary considerations in re-introduction and translocation projects
Authors: Woodford M H , Kock R A 
Published: November 2023

Abstract
Wildlife management is a rapidly developing science and relocation of wild species for reinforcement of a population or re-introduction is becoming a popular conservation technique. However, when wild animals are moved from one place to another, inherent disease risks are evident. These risks can be assessed in advance and minimized if appropriate and timely veterinary precautions are taken.
Training for life after release: simian primates as examples
Authors: BOX Hilary O 
Published: November 2023

Abstract
Using simian primates as an example, the paper outlines the variety of skills required to adjust adequately to a natural environment after release from captive conditions. Specific examples are given from wild-born individuals which have been rehabilitated by release programmes after periods in captivity. Examples are also taken from programmes of environmental enrichment in captivity which encourage natural behaviour in various species of primates that have been bred in captivity, and thus maximize the chances that their subsequent re-introduction into the wild will succeed. In addition, a number of issues are raised with reference to differences among species in their behavioural and physiological responsiveness to changes in their environments. It is argued that these issues are an important source of hypotheses in the development of training programmes for species with different predispositions, as in their social organization.
Costs of a re-introduction and criteria for success: accounting and accountability in the Golden Lion Tamarin Conservation Program
Authors: Kleiman Devra G , Beck Benjamin B , Dietz James M , Dietz Lou Ann 
Published: November 2023

Abstract
In this paper, we review the separate components of the Golden Lion Tamarin Conservation Program, including field studies, education, habitat preservation and restoration and re-introduction. We summarize the history of the captive population and provide an estimate of the annual cost of maintaining the captive population at 550 animals in 100 institutions. We then develop estimates of the ‘costs’ of the re¬ introduction programme, including salaries of Brazilian and US personnel, construction costs, animal and human facilities, vehicles and transportation and supplies and equipment. By considering the number of tamarins surviving as a result of the re¬ introduction and the total costs, we estimate that one surviving re-introduced golden lion tamarin has cost approximately $22,000 to date.
We then evaluate the other benefits of the programme, including the effects of the re-introduction on habitat preservation and augmentation as well as education in conservation, ecology and wildlife management, locally, nationally and inter¬ nationally.
Viable population strategies for re introduction programmes
Authors: Foose Thomas J 
Published: November 2023

Abstract
Re-introduction programmes should be based on viable population strategies because of stochastic risks to the small population that will characterize most taxa for which re-introduction is attempted. These strategies will entail metapopulations incorporating both captive and wild subpopulations which will need to be interactively managed for mutual support and survival. Even when re-introductions have to be opportunistic, they should occur within the strategic framework of a metapopulation survival masterplan.
The red wolf as a model for carnivore re-introductions
Authors: Moore Donald E , Smith Roland 
Published: November 2023

Abstract
The unique red wolf became extinct in the wild in the 1970s because of 100 years of human encroachment, destruction of bottomland forest and coastal marsh habitat, persecution and predator control activities. In 1973, a Red Wolf Captive Breeding Program was established by the US Fish and Wildlife Service and Point Defiance Zoo in Tacoma, Washington. Today there are about 125 red wolves in captivity in zoological parks and national wildlife refuges. The US Fish and Wildlife Service, in co-operation with the AAZPA SSP Propagation Group, released captive-born red wolves into National Wildlife Refuges in the south-eastern United States, beginning in September 1987.