bluuebunny/crossref_metadata_2025 huggingface dataset:
Africa: Soldiers, Sexually Transmitted Diseases, and War
Authors: Smallman-Raynor Matthew , Cliff Andrew
Published: November 2020

As we observed in Chapter 4, from time immemorial, sexually transmitted diseases (STDs) have been a scourge of military personnel and of the wars in which they were deployed. So, in her excellent historical review, Venereal Diseases in the Major Armies and Navies of the World, Josephine Hinrichsen (1944, 1945a, 1945b) traces the military problem of female prostitution—and, by implication, the associated spread of STDs—to the great army camps of classical Greece and Rome. In more recent times, the Italian War of Charles VIII (1494–5) provides one of the most dramatic instances of the intersection of armies, STDs, and war—the pan-European dissemination of venereal syphilis by the disbanded mercenary troops of France, Germany, and Italy (see Sect. 2.3.3). Thereafter, epidemics of syphilis and other venereal diseases followed wave-like on wars in Europe and elsewhere (Prinzing, 1916: 18). In Sweden, the syphilis epidemics of 1762 and 1792 were sparked by military returnees from the Seven Years’ (1756–63) and the Russo-Swedish (1788–90) Wars. In the nineteenth century, the Russo-Turkish Wars (1806–12, 1828–9) contributed materially to the spread of the disease in the Balkans (Hinrichsen, 1944). Elsewhere, in World War II (1939–45), the high-level transmission of gonorrhoea, chancroid, and syphilis among Allied personnel in the Burma–India, Africa–Middle East, and Mediterranean Theatres provides a twentieth-century example of the war-related problem of STDs (Sternberg et al., 1960). As Berg (1984: 90) notes, the historical concern of the military wth STDs was eminently a practical one. Prior to the era of antibiotics (penicillin was first used in the military treatment of syphilis and gonorrhoea in 1943), STDs were associated with extended periods of hospital treatment with correspondingly high economic and medical manpower costs to the armed forces. Some impression of the dimensions of the STD problem for one army (US Army) and war (World War I) can be gained from Table 10.1. During a 21-month period of military engagement, April 1917–December 1918, three STDs (chancroid, gonorrhoea, and syphilis) accounted for over 6.8 million days of lost service in the US Army.
Proximity, Organization, and Culture
Authors: Gertler Meric S.
Published: November 2020

Since the late 1980s a growing number of geographers and other social scientists have chronicled the apparent rise of post-Fordist economic systems (Scott and Storper 1987; Schoenberger 1988; Harvey 1989; Storper and Walker 1989; Boyer 1990; Storper 1997). These systems are said to employ a flexible approach to production reflected in employment relations, the organization of work within firms, and the broader social division of labour (Cooke and Morgan 1998). To some, the heart of this transformation lies in the rise of a new set offerees of production (Walker 1994). In particular, they point to a new set of flexible process technologies whose programmable properties offer producers prospects of great versatility, limited downtime, unparalleled precision, and superior quality. The same technologies are said to hold the potential to unleash the creative potential of workers, and to compel manufacturers to establish a new regime of co-operation on the shopfloor (Florida 1991). Despite the popularity of such arguments, their unqualified acceptance has not been universal. A critical literature has arisen which, among other things, questions the pervasiveness of such practices, especially in locations outside the paradigmatic flexible production regions (Gertler 1988; 1992; Sayer 1989; Pudup 1992). The evidence reviewed in Ch. 2 attests that, while rates of adoption of flexible technologies such as computerized numerical control (CNC) are reasonably high amongst manufacturers in countries such as the United States, Great Britain, and Canada, many firms in these countries have experienced considerable difficulty in trying to implement such technologies effectively (Jaikumar 1986; Beatty 1987; Meurer, Sobel, and Wolfe 1987; Kelley and Brooks 1988; Turnbull 1989; Oakey and O’Farrell 1992). Furthermore, the discussion in Ch. 2 also shows that there is an apparent regularity to the geography of technology adoption difficulty that is highly suggestive of its roots. Many of these implementation difficulties seem to arise in older, mature industrial regions, where manufacturing firms are far removed from the major production sites of the new flexible production technologies. Increasingly, the leading producers of these process technologies are to be found in such countries as Germany, Japan, and Italy, while once-dominant American machinery producers have seen their market shares drop significantly, both at home and abroad (Graham 1993).
Introduction: The Power of Water
Authors: Swyngedouw Erik
Published: November 2020

Water is indispensable ‘stuff’ for maintaining the metabolism, not only of our human bodies, but also of the wider social fabric. The very sustainability of cities and the practices of everyday life that constitute ‘the urban’ are predicated upon and conditioned by the supply, circulation, and elimination of water. The complex web of the ‘Metabolisms of Cities’ (Wolman 1965: 179) relies on the perpetual circulation of water into, through, and out of the city. Without an uninterrupted flow of water, the maelstrom of city life and the mesmerizing collage of interwoven practices that constitute the very essence of urbanity are hard to imagine. It is difficult, if not impossible, for most of us to even think about living without water for drinking, washing, bathing, cooking, or cleaning for more than a few hours. Indeed, like food, water is both a biological necessity and a key economic commodity, as well as being the source of an intricate and rich cultural and symbolic power (see Bachelard 1942). But while the supply of food, clothing, and durable goods can be handled through local, decentralized, individual initiative, the supply of water is routinely— although by no means necessarily or exclusively—organized by means of large bureaucratic and engineering control systems, collective intervention and action, and centralized decision-making systems (see Wittfogel 1957;Worster 1985; Lorrain 1997; Donahue and Johnston 1998). Such centralized and hierarchical systems, whether privately or publicly owned, enable monopoly control and, given the commodity character of water, permit the extraction of monopoly profits in addition to the powerful social and political control that goes with monopolistic control over vital goods. Contrary to the rural realm where—at least under non-arid conditions—water of a reasonable quality is easily and often readily available, urban water supply and access relies on the perpetual transformation, mastering, and harnessing of ‘natural’water. Urban water is necessarily transformed, ‘metabolized’ water, not only in terms of its physico-chemical characteristics, but also in terms of its social characteristics and its symbolic and cultural meanings.
Economic Geography
Authors: Harrington James W. , Barnes Trevor J.
Published: November 2020

To read the comparable chapter on economic geography in Geography in America is to recall a world, and a way of viewing that world, that seems remote. For one thing, that chapter was called Industrial Geography. There were good reasons why industrial geography was so prominent in the last report. The 1970s and 1980s were a period of fundamental industrial change in Western economies involving deindustrialization and lay-offs, restructuring of methods of production, the emergence of new manufacturing and service sectors, and new forms of international economic organization supported by innovations in telecommunications, transportation, and corporate organization and management. All those substantive issues remain important, and in some cases central, to present economic geographical research. Changed, though, is the conceptualization of those issues. In particular, newer approaches tend to blur the boundary between the economic part of economic geography, and other social, cultural, and political geographical practices. Some have labeled this move “the cultural turn” (Crang 1997; Thrift and Olds 1996; Barnes 1996b), but this description is too narrow because more than just the cultural is at stake. Rather, the very idea of the economic is being reconceived. The economic is no longer conceptualized as sovereign, isolated, and an entity unto itself, but porous and dependent, bleeding into other spheres as they bleed into it. To use Karl Polyani’s (1944) term, which is often deployed in this literature, the economy is “embedded” within broader processes. There are at least two reasons for the reconceptualization of the economic by economic geographers. One is internal to the academy, and is bound up with a broader intellectual shift in the social sciences and humanities that is increasingly suspicious of essentialized entities such as “the economy” (Barnes 1996a; Gibson-Graham 1996; Lee and Wills 1997). A second source of change is the actual geography of economic activities. The economic geographical landscape of the 1990s seems quite different from the one written about in the last report, and thereby demands a new theoretical vocabulary in which to be represented. In the last report, for example, there was no mention of Fordism or post-Fordism, flexibility or economies of scope, localities or local modes of regulation, growth coalitions or territorial complexes, or glocalization or even globalization.
Military Geography
Authors: Palka Eugene J.
Published: November 2020

In the benchmark publication American Geography: Inventory and Prospect (1954), Joseph Russell reported that military geography had long been recognized as a legitimate subfield in American geography. Despite the occasional controversy surrounding the subfield since his assessment (Association of American Geographers 1972; Lacoste 1973), and the general period of drought it experienced within American academic geography during the Vietnam era, military geography displays unquestionable resilience at the dawn of the twenty-first century. The subfield links geography and military science, and in one respect is a type of applied geography, employing the knowledge, methods, techniques, and concepts of the discipline to military affairs, places, and regions. In another sense, military geography can be approached from an historical perspective (Davies 1946; Meigs 1961; Winters 1998), with emphasis on the impact of physical or human geographic conditions on the outcomes of decisive battles, campaigns, or wars. In either case, military geography continues to keep pace with technological developments and seeks to apply geographic information, principles, and tools to military situations or problems during peacetime or war. Throughout the twentieth century, professional and academic geographers made enormous contributions to the US Military’s understanding of distant places and cultures. The vast collection of Area Handbooks found in most university libraries, serves as testament to the significant effort by geographers during wartime. Although some of the work remains hidden by security classification, a casual glance at Munn’s (1980) summary of the roles of geographers within the Department of Defense (DOD) enables one to appreciate the discipline’s far-reaching impact on military affairs. The value of military geography within a theater of war can hardly be disputed. The subfield has also been important during peacetime, however, providing an important forum for the continuing discourse among geographers, military planners, political officials, and government agencies, as each relies upon geographic tools and information to address a wide range of problems within the national security and defense arenas. Despite the subdiscipline’s well-established tenure, the Military Geography Specialty Group is in its infancy. The time-lag is attributable to the subfield’s tumultuous experience during the Vietnam era and the associated demise that ensued.
Geography of Africa
Authors: Kalipeni Ezekiel , Oppong Joseph R.
Published: November 2020

This chapter reviews the state of North American geographical research on Africa in the 1990s. During the 1980s research on Africa dwelt on the many crises, some real and some imagined, usually sensationalized by the media, such as the collapse of the state in Sierra Leone, Liberia, Somalia, and Rwanda and the economic shocks of structural adjustment programs. The 1990s witnessed momentous positive changes. For example, apartheid ended in South Africa and emerging democratic systems replaced dictatorial regimes in Malawi and Zambia. Persuaded that Africa had made progress on many fronts largely due to self-generated advances, some scholars began to highlight the positive new developments (Gaile and Ferguson 1996). Due to space limitations, selecting works to include in this review has been difficult. In many instances we stayed within five cited works (first authorship) for anyone scholar to ensure focus on the most important works and to achieve a sense of balance in the works cited. Thus, research reviewed in this chapter should be treated as a sample of the variety and quality of North American geographical work on Africa. One major challenge was where to draw the boundary between “geography,” “not quite geography,” and “by North American authors” versus others. In these days of globalized research paradigms, geography has benefited tremendously from interchanging ideas with other social and natural science disciplines. Thus, separating North American geographic research in the 1990s from other groundbreaking works that profoundly influence the discipline of geography is difficult. For example, while the empirical subject matter included agriculture, health, gender, and development issues, the related theoretical paradigm often included representation, discourse, resistance, and indigenous development within broader frameworks influenced by the ideas of social science scholars such as Foucault (1970, 1977, 1980), Said (1978), Sen (1981, 1990), and Scott (1977, 1987). This chapter engages these debates. Building upon T. J. Bassett’s (1989) review of research in the 1980s, the chapter develops a typology for the growing research on African issues and related theoretical orientations (Table 36.1). The reviewed works fall into the three main subdisciplines of geography—human geography (by far the most dominant), physical geography now commonly referred to as earth systems science or global change studies, and geographic information systems (GIS).
American Indian Geography
Authors: Rundstrom Robert , Deur Douglas
Published: November 2020

Contemporary geographical research concerning North America’s native peoples is most conspicuous for its remarkably diverse set of subjects, methods, and epistemological stances. Indeed, it would be hard to find another AAG specialty group whose members do research in as many corners of the natural and social sciences and humanities. Some perspectives developed quite recently, while others emanate from a century of prior research by geographers, especially Carl Sauer and his students. We think these observations important enough to require opening our review with a description, albeit a painfully brief one, of the historical context for the current scene. In the early twentieth century, as now, there was a great deal of cross-fertilization between anthropology and geography. Deterministic thinking associated with environmentalist theory (e.g. Hans 1925; Huntington 1919; Semple 1903) elicited many critical responses from both fields. For example, the geographer-turned-anthropologist Franz Boas and his students sought to illuminate the full complexity of Native American life, producing a vast corpus of empirical studies. Many addressed geographical topics, including Native North American place-names, environmental knowledge, and resource use. These works were frequently termed “ethnogeographies” (e.g. Barrett 1908; Boas 1934; Harrington 1916). Others attempted sweeping continental studies of regional variation based on historical and cultural processes (Kroeber 1939; Wissler 1926). The historicist critique of environmentalist theory resonated with a young geographer, Carl Sauer. Sauer (1920) long had interests in American Indian land-use practices, or “land management” in current parlance. Regular interaction with Boas’s students, especially Kroeber and Lowie, coupled with independent development of their own geographical ideas, led Sauer and his students to expand their research on North American Indian cultural geography, including such subjects as settlement patterns (e.g. Sauer and Brand 1930), plant use (e.g. Carter 1945), and resources and material and oral culture (e.g. Kniffen 1939). Sauer, his large number of Ph.D. students, and his student’s students, continued to define this research agenda throughout the twentieth century (e.g. Kniffen et al. 1987; Sauer 1971). The continued relevance of this work was signaled recently by the reissue of two classic texts in new editions (Denevan 1992a; Waterman 1993).
Geographic Perspectives on Women
Authors: Oberhauser Ann M. , Rubinoff Donna
Published: November 2020

Since its inception in the mid-1970s, feminist geography has significantly impacted the discipline. Open nearly any human geography textbook, review course offerings in most of the top geography programs, or examine recent publications by well-known human geographers and you will discover the influence of gender and feminist perspectives. This has not always been the case, however. In the previous volume of Geography in America, the chapter written for the Geographic Perspectives on Women (GPOW) specialty group noted that until recently, geography was written as if “men were representative of the species” (Gruntfest 1989: 673). Many areas of the discipline have gone beyond this approach and are beginning to recognize the role of gender in human spatial behavior. This chapter draws from the foundations of feminist geography that highlight the role of women in geographical analysis before focusing on the multiple voices and variety of perspectives that comprise this area of the discipline. The thematic topics presented in this chapter address feminist analyses of methodology, gender and work, Third World development, cultural geography, identity and difference, and pedagogy. This discussion is by no means exhaustive, but addresses those issues that have been particularly influential during the 1990s. While feminist geographers borrow from, and contribute to, research outside the discipline, this chapter largely focuses on work undertaken by researchers more formally associated with geography. The discussion also includes work by non-American geographers due to the collaborative and international nature of feminist geography that makes it difficult to limit research to one country. The cross-fertilization of ideas and experiences is evident in the growing number of conferences, publications, institutional exchanges, and research endeavors that involve a variety of feminist scholars from multiple disciplines and nationalities. According to the editors of this book, our charge was to write an assessment of feminist geography that is “comprehensive, current, forward-looking, and influential.” The task of writing this chapter has occurred in a participatory and collaborative manner that reflects feminist projects (and produced some lively telephone conversations!). As authors, we represent a diverse group of scholars in terms of our positions in the academy, areas of specialization, and institutional affiliations.
Plagues and Peoples The Long Demographic Cycle, 1250–1670
Authors: Smith Richard , slack paul
Published: November 2020

The following discussion is focused around a consideration of what will be termed a ‘long population cycle’ from the late thirteenth century through to the late seventeenth century. In so far as this consideration is directed towards a society that may be unambiguously categorized as ‘preindustrial’ throughout this era, it is unavoidable that at various stages of the argument it will be necessary to engage with the classical Malthusian model of the relationship between living standards and population growth rates, although some assessment will be made of the role played by epidemic disease in determining both the width and depth of the cycle. In addition an attempt will be made to chart the principal changes to the economy and society relating to shifting numbers and geographical distribution of persons on the land during the extensive phases of demographic decline and recovery. Before engaging with theory and explanations of long-term trends some mundanely empirical steps will be taken so that the broad dimensions of the ‘cycle’ might be established. Empiricism is no straightforward endeavour in the absence of serial census records of any kind, let alone individual census counts for randomly distributed moments, over this extensive fourcentury period. It is at least fortunate that the final 150 years of the cycle yield evidence from parish registers, which in recent years have been exploited by historical demographers in ways that make it possible to establish annual population totals and vital rates from 1541. In attempting to establish population trends and totals before a system of parochial registration of baptisms, marriages, and burials was in place, historians succumb to what Sir Michael Postan (1966: 561) once termed the ‘lure of aggregates’ by engaging in decidedly problematic, although unavoidable, exercises. In this present discussion we are in danger of incurring Postan’s wrath since we employ one central and vital source that relates to demographic conditions in one year only, around which a key argument in this discussion revolves.
Country and Town: The Primary, Secondary, and Tertiary Peopling of England in the Early Modern Period
Authors: Wrigley E. A. , Langton John
Published: November 2020

There are many ways of depicting the constitution of a given society and of defining and measuring the changes within it. They reflect the interests and purposes of the scholars concerned, tempered by the source materials available to them. This chapter reflects the conviction that the occupational structure of a society and the changes therein offer the opportunity to gain an insight into much else about that society and its development. The way in which men and women earned a living reveals much about them and their communities. Though true of all societies, this was perhaps especially true of societies before the industrial revolution. It is instructive to consider why this should be so. At bottom it follows from the fact that occupational structure in pre-industrial societies reflected the hierarchical nature of human needs, which produced some notable and readily observable regularities. The thinking and terminology of the classical economists reflected their appreciation of this point. They frequently referred to what they termed the necessities of life, of which there were four: food, shelter, clothing, and fuel. These they distinguished both from what they characterized as comforts, other material products which were less central to life than the necessities but eagerly sought after when circumstances permitted; and from luxuries, goods or services to which only the affluent could aspire. If circumstances are sufficiently bleak people will favour spending on necessities above all other forms of expenditure, so that a very high proportion of the total spending of the poor will be devoted solely to necessities and above all to food. It was not uncommon for an impoverished household in early modern England to spend as much as three-quarters of its income on food alone and a still higher proportion, of course, on the four necessities taken together. But when income rises the proportion spent on necessities declines. If a poor man’s income suddenly doubles, he and his family will spend more thereafter on food but their expenditure on food will not double.
Yet another constructivization of classical logic
Authors: Baratella Stefano , Berardi Stefano
Published: November 2020

The aim of this paper is to provide a way of extracting the constructive content of a certain family of classical proofs directly from the proofs themselves. The paper itself is written in a purely constructive style. Our work is inspired by the game interpretations of classical logic due to Novikov (1943) and Coquand (1995). These interpretations date back to Gentzen (1969) and Bernays (1970) and were recently studied by Coquand (1995) who made use of technical tools developed by Novikov (1943). We will introduce an interpretation which is a short and compact description of the meaning assigned to classical formulas by Coquand’s interpretation. Contrary to Coquand, we will completely avoid any game terminology, by making use of the intuitionistic notion of continuous computation. A posteriori, our interpretation turns out to be related to Kreisel’s no-counterexample interpretation (Kreisel 1957) but, compared with his, it provides simpler constructive proofs. The reader is referred to Baratella and Berardi (1997) for a number of examples of constructive proofs provided by our interpretation that can be used for a comparison. Indeed, our interpretation is a fragment of Coquand’s that can be easily expanded to a variant of his. However, we claim that our interpretation suffices as long as we are only interested in the constructive meaning of classical formulas (whilst we need Coquand’s if we are interested in computations lying behind the constructive meaning). We will support this claim by proving, as the main result, that our interpretation is intuitionistically complete, in the same way as Coquand’s (Herbelin 1995). That is, we will intuitionistically prove that a formula is derivable in infmitary classical logic if and only if its interpretation holds. Since infinitary classical logic is classically complete, loosely speaking we can restate our result as follows: the classical truth of a classical formula is intuitionistically equivalent to the intuitionistic truth of the constructive interpretation of the formula. We also recall that Godel’s Dialectica interpretation is not intuitionistically complete (see section 7). In this regard, see also Berardi (1997). In addition, we point out that, contrary to the game interpretations, our interpretation is not a sort of reformulation of what is going on in the sequent calculus.
Building up a toolbox for Martin-Löf’s type theory: subset theory
Authors: Sambin Giovanni , Valentini Silvio
Published: November 2020

Beginning in 1970, Per Martin-Löf has developed an intuitionistic type theory (hence-forth type theory for short) as a constructive alternative to the usual foundation of mathematics based on classical set theory. We assume the reader is aware at least of the main peculiarities of type theory, as formulated in Martin-Löf 1984 or Nordström et al. 1990; here we recall some of them to be able to introduce our point of view. The form of type theory is that of a logical calculus, where inference rules to derive judgements are at the same time set-theoretic constructions, because of the “propositions-as-sets” interpretation. The spirit of type theory—expressing our interpretation in a single sentence-—is to adopt those notions and rules which keep total control of the amount of information contained in the different forms of judgement. We now briefly justify this claim. First of all, the judgement asserting the truth of a proposition A, which from an intuitionistic point of view means the existence of a verification of A, in type theory is replaced by the judgement a ∈ A which explicitly exhibits a verification a of A. In fact, it would be unwise, for a constructivist, to throw away the specific verification of A which must be known to be able to assert the existence of a verification! The judgement that A is a set, which from an intuitionistic point of view means that there exists an inductive presentation of A, is treated in type theory in a quite similar way (even if in this case no notation analogous to a ∈ A is used) since the judgement A set in type theory becomes explicit knowledge of the specific inductive presentation of A. In fact, the rules for primitive types and for type constructors are so devised that whenever a judgement A set is proved, it means that one also has complete information on the rules which describe how canonical elements of A are formed. Such a property, which might look like a peculiarity of type theory, is as a matter of fact necessary in order to give a coherent constructive treatment of quantifiers.
An introduction to well-ordering proofs in Martin-Löf’s type theory
Authors: Setzer Anton
Published: November 2020

The proof-theoretic strength α of a theory is the supremum of all ordinals up to which we can prove transfmite induction in that theory. Whereas for classical theories the main problem is to show that α is an upper bound for the strength—this usually means to reduce the theory to a weak theory like primitive recursive arithmetic or Heyting arithmetic extended by transfmite induction up to α, which can be considered to be more constructive than the classical theory itself—for constructive theories this is in most cases not difficult, since we can easily build a term model in a classical theory of known strength. For constructive theories in general the main problem is to show that α is a lower bound: that despite the restricted principles available one has a proof-theoretically strong theory. In this article we will concentrate on the direct method for showing that α is a lower bound, namely well-ordering proofs: to carry out in the theory a sequence of proofs of the well-foundedness of linear orderings of order type αn, such that supn∈ω αn = α. Such proofs can be considered to be the logically most complex proofs which one can carry out in the theory; in most cases, in addition to transfinite induction up to αn for each n, only primitive recursive arithmetic is needed in order to analyze the theory proof-theoretically and in order to prove the same Π02-sentences. Griffor and Rathjen (1994) have used the more indirect method of interpreting theories of known strength in type theory for obtaining lower bounds for the strength of it. Apart from the fact that in the case of one universe and W-type Griffor and Rathjens’ approach did not yield sharp bounds, we believe that the direct method has the advantage of giving a deeper insight into the theory, since one examines the principles of the theory directly without referring to the analysis of another theory, and that the programs obtained by it are of independent interest. In Setzer (1995) and Setzer (1996) we have carried out well-ordering proofs for Martin-Löf’s type theory with W-type and one universe and for the Mahlo universe.
Material progress and immaterial observations: An exhibition of molecules that make life a little easier
Authors: Emsley John
Published: November 2020

You may think of polymers as entirely manufactured and therefore unnatural, but they are often the chemists’ attempts to supplement and improve on the biological polymers that nature produces. Cotton, ivory, leather, linen, paper, rubber, silk, wood and wool are wonderful materials made from the biological polymers that plants and animals produce, and which have evolved to serve such useful ends as providing protective outer layers, insulation, reinforcement, weaponry and so on. Humans learned that with a little modification they could turn these polymers into quite useful articles, such as briefs and briefcases, condoms and tea cosies, tickets and toothpicks. Sometimes we want polymers with features that never evolved in nature, such as non-cracking insulation for electric cable, clothes that can be unpacked after a long voyage and still be without creases, or pans in which to fry eggs without them sticking. For these polymers we have had to look to chemists. Most of the portraits in this Gallery are of these kinds of polymers—materials that do not have natural equivalents. Polymers are rather special kinds of molecules consisting of long chains, usually made up of carbon atoms, to which other atoms, such as hydrogen, fluorine and chlorine, are attached. The older name for polymers is plastics, and you probably know several of them by name— polythene, polystyrene, Teflon, Orion—but these are only a few of the many that now play an important role in our lives. Whatever role polymers play, they cause many of us to adopt quite strong attitudes towards them. A few of us admire them, many of us ignore them, but a growing number despise them and a few abhor them and will avoid them at all costs. To a chemist, this opposition to polymers seems rather strange. By the time you come to the end of this exhibition I hope that visitors with strong views will have seen enough to persuade them to change their mind. Attitudes towards plastics have changed over the past half-century. In the 19305, when cellophane, PVC, polystyrene, Perspex and nylon were launched, plastics were welcomed.
Metrics Spaces for the Matrix Groups
Authors: Grenander Ulf , Miller Michael I.
Published: November 2020

In this chapter the metric space structure of shape is developed. We do this by first studying the action of the matrix groups on the coordinate systems of shape. We begin by reviewing the well-known properties of the finite-dimensional matrix groups, including their properties as smooth Riemannian manifolds, allowing us to develop metric distances between the groupelements. We explore the construction of the metric structure of these diffeomorphisms and develop many of the properties which hold for the finite dimensional matrix groups and subsequently in the infinite dimensional setting as well.
SIMD, Single Instruction Multiple Data
Authors: Petersen Wesley , Arbenz Peter
Published: November 2020

The single instruction, multiple data (SIMD) mode is the simplest method of parallelism and now becoming the most common. In most cases this SIMD mode means the same as vectorization. Ten years ago, ve ctor computers were expensive but reasonably simple to program. Today, encouraged by multimedia applications, vector hardware is now commonly available in Intel Pentium III and Pentium 4 PCs, and Apple/Motorola G-4 machines. In this chapter, we will cover both old and new and find that the old paradigms for programming were simpler because CMOS or ECL memories permitted easy non-unit stride memory access. Most of the ideas are the same, so the simpler programming methodology makes it easy to understand the concepts. As PC and Mac compilers improve, perhaps automatic vectorization will become as effective as on the older non-cache machines. In the meantime, on PCs and Macs we will often need to use intrinsics ([23, 22, 51]). It seems at first that the intrinsics keep a programmer close to the hardware, which is not a bad thing, but this is somewhat misleading. Hardware control in this method of programming is only indirect. Actual register assignments are made by the compiler and may not be quite what the programmer wants. The SSE2 or Altivec programming serves to illustrate a form of instruction level parallelism we wish to emphasize. This form, SIMD or vectorization, has single instructions which operate on multiple data. There are variants on this theme which use templates or macros which consist of multiple instructions carefully scheduled to accomplish the same objective, but are not strictly speaking SIMD, for example see Section 1.2.2.1. Intrinsics are C macros which contain one or more SIMD instructions to execute certain operations on multiple data, usually 4-words/time in our case. Data are explicitly declared mm128 datatypes in the Intel SSE case and vector variables using the G-4 Altivec. Our examples will show you how this works. Four basic concepts are important: Consistent with our notion that examples are the best way to learn, several will be illustrated: • from linear algebra, the Level 1 basic linear algebra subprograms (BLAS) — vector updates (-axpy) — reduction operations and linear searches • recurrence formulae and polynomial evaluations • uniform random number generation.
MIMD, Multiple Instruction, Multiple Data
Authors: Petersen Wesley , Arbenz Peter
Published: November 2020

The Multiple instruction, multiple data (MIMD) programming model usually refers to computing on distributed memory machines with multiple independent processors. Although processors may run independent instruction streams, we are interested in streams that are always portions of a single program. Between processors which share a coherent memory view (within a node), data access is immediate, whereas between nodes data access is effected by message passing. In this book, we use MPI for such message passing. MPI has emerged as a more/less standard message passing system used on both shared memory and distributed memory machines. It is often the case that although the system consists of multiple independent instruction streams, the programming model is not too different from SIMD. Namely, the totality of a program is logically split into many independent tasks each processed by a group (see Appendix D) of processes—but the overall program is effectively single threaded at the beginning, and likewise at the end. The MIMD model, however, is extremely flexible in that no one process is always master and the other processes slaves. A communicator group of processes performs certain tasks, usually with an arbitrary master/slave relationship. One process may be assigned to be master (or root) and coordinates the tasks of others in the group. We emphasize that the assignments of which is root is arbitrary—any processor may be chosen. Frequently, however, this choice is one of convenience—a file server node, for example. Processors and memory are connected by a network, for example, Figure 5.1. In this form, each processor has its own local memory. This is not always the case: The Cray X1, and NEC SX-6 through SX-8 series machines, have common memory within nodes. Within a node, memory coherency is maintained within local caches. Between nodes, it remains the programmer’s responsibility to assure a proper read–update relationship in the shared data. Data updated by one set of processes should not be clobbered by another set until the data are properly used.
Magnetic phenomena
Authors: Newnham Robert E.
Published: November 2020

In this chapter we deal with a number of magnetic properties and their directional dependence: pyromagnetism, magnetic susceptibility, magnetoelectricity, and piezomagnetism. In the course of dealing with these properties, two new ideas are introduced: magnetic symmetry and axial tensors. Moving electric charge generates magnetic fields and magnetization. Macroscopically, an electric current i flowing in a coil of n turns per meter produces a magnetic field H = ni amperes/meter [A/m]. On the atomic scale, magnetization arises from unpaired electron spins and unbalanced electronic orbital motion. The weber [Wb] is the basic unit of magnetic charge m. The force between two magnetic charges m1 and m2 is where r is the separation distance and μ0 (=4π×10−7 H/m) is the permeability of vacuum. In a magnetic field H, magnetic charge experiences a force F = mH [N]. North and south poles (magnetic charges) separated by a distance r create magnetic dipole moments mr [Wb m]. Magnetic dipole moments provide a convenient way of picturing the atomistic origins arising from moving electric charge. Magnetization (I) is the magnetic dipole moment per unit volume and is expressed in units of Wb m/m3 = Wb/m2. The magnetic flux density (B = I + μ0H) is also in Wb/m2 and is analogous to the electric displacement D. All materials respond to magnetic fields, producing a magnetization I = χH, and a magnetic flux density B = μH where χ is the magnetic susceptibility and μ is the magnetic permeability. Both χ and μ are in henries/m (H/m). The permeability μ = χ + μ0 and is analogous to electric permittivity. χ and μ are sometimes expressed as dimensionless quantities (x ̅ and μ ̅ and ) like the dielectric constant, where = x ̅/μ0 and = μ ̅/μ0. Other magnetic properties will be defined later in the chapter. A schematic view of the submicroscopic origins of magnetic phenomena is presented in Fig. 14.1. Most materials are diamagnetic with only a weak magnetic response induced by an applied magnetic field.
Thermal conductivity
Authors: Newnham Robert E.
Published: November 2020

When different portions of a solid are at different temperatures, thermal energy is transported from the warmer to the cooler regions. The thermal conductivity coefficient provides a quantitative measure of the rate at which thermal energy is transported along the thermal gradient. Thermal conductivity coefficients k relate the heat flux h [W/m2] to temperature gradient dT/dZ. In tensor form, The minus sign appears because heat flows from hot to cold. Thermal conductivity is measured in units of W/m K. Four contributions to thermal conductivity are illustrated in Fig. 18.1. The two principal mechanisms are from conduction electrons and from lattice vibration phonons. In transparent solids, especially at high temperature, photon transport can also be important. In porous media, convection currents from gas or liquid molecules can contribute to the thermal conductivity. Thermal conductivity is a polar second rank tensor like electric permittivity, magnetic susceptibility, and electrical resistivity but there is a basic question regarding the symmetry of transport properties such as electrical and thermal conductivity. The symmetry of tensors is partly dictated by geometrical considerations through Neumann’s Principle, and partly through thermodynamic arguments. For triclinic crystals there are nine nonzero conductivity coefficients kij . If the tensor is symmetric then kij = kji, and there are only six independent coefficients to be determined. For the dielectric constant it was shown that Kij = Kji, based on thermostatic energy arguments (Section 9.2). This argument does not hold for transport properties, but there is another principle based on irreversible thermodynamics. Onsager’s Theorem states that for transport properties, involving the flow of charge, heat, or atomic species, then . . . kij = kji. . . . The proof of Onsager’s Theorem depends on statistical mechanics and is beyond the scope of this book. From a practical point of view, Onsager’s Theorem is not very important because most transport experiments are performed on high symmetry metals, semiconductors, and insulators.
Introduction To Quantum Relaxation Processes
Authors: Nitzan Abraham
Published: November 2020

The first question to ask about the phenomenon of relaxation is why it occurs at all. Both the Newton and the Schrödinger equations are symmetrical under time reversal: The Newton equation, dx/dt = v ; dv/dt = −∂V/∂x, implies that particles obeying this law of motion will retrace their trajectory back in time after changing the sign of both the time t and the particle velocities v. The Schrödinger equation, ∂ψ/∂t = −(i/.h) Ĥ ψ, implies that if (ψ (t) is a solution then ψ *(−t) is also one, so that observables which depend on |ψ|2 are symmetric in time. On the other hand, nature clearly evolves asymmetrically as asserted by the second law of thermodynamics. How does this asymmetry arise in a system that obeys temporal symmetry in its time evolution? Readers with background in thermodynamics and statistical mechanics have encountered the intuitive answer: Irreversibility in a system with many degrees of freedom is essentially a manifestation of the system “getting lost in phase space”:Asystem starts from a given state and evolves in time. If the number of accessible states is huge, the probability that the system will find its way back to the initial state in finite time is vanishingly small, so that an observer who monitors properties associated with the initial state will see an irreversible evolution. The question is how is this irreversible behavior manifested through the reversible equations of motion, and how does it show in the quantitative description of the time evolution. This chapter provides an introduction to this subject using the time-dependent Schrödinger equation as a starting point. Chapter 10 discusses more advanced aspects of this problem within the framework of the quantum Liouville equation and the density operator formalism.
The Spin–Boson Model
Authors: Nitzan Abraham
Published: November 2020

In a generic quantum mechanical description of a molecule interacting with its thermal environment, the molecule is represented as a few level system (in the simplest description just two, for example, ground and excited states) and the environment is often modeled as a bath of harmonic oscillators. The resulting theoretical framework is known as the spin–boson model, a term that seems to have emerged in the Kondo problem literature (which deals with the behavior of magnetic impurities in metals) during the 1960s, but is now used in a much broader context. Indeed, it has become one of the central models of theoretical physics, with applications in physics, chemistry, and biology that range far beyond the subject of this book. Transitions between molecular electronic states coupled to nuclear vibrations, environmental phonons, and photon modes of the radiation field fall within this class of problems. The present chapter discusses this model and some of its mathematical implications. The reader may note that some of the subjects discussed in Chapter 9 are reiterated here in this more general framework. In Sections 2.2 and 2.9 we have discussed the dynamics of the two-level system and of the harmonic oscillator, respectively. These exactly soluble models are often used as prototypes of important classes of physical system. The harmonic oscillator is an exact model for a mode of the radiation field and provides good starting points for describing nuclear motions in molecules and in solid environments. It can also describe the short-time dynamics of liquid environments via the instantaneous normal mode approach. In fact, many linear response treatments in both classical and quantum dynamics lead to harmonic oscillator models: Linear response implies that forces responsible for the return of a system to equilibrium depend linearly on the deviation from equilibrium—a harmonic oscillator property! We will see a specific example of this phenomenology in our discussion of dielectric response in Section 16.9.