bluuebunny/crossref_metadata_2025 huggingface dataset:
Metal deposition and dissolution
Authors: Schmickler Wolfgang
Published: November 2020

On a liquid metal electrode all surface sites are equivalent, and the deposition of a metal ion from the solution is conceptually simple: The ion loses a part of its solvation sheath, is transferred to the metal surface, and is discharged simultaneously; after a slight rearrangement of the surface atoms it is incorporated into the electrode. The details of the process are little understood, but it seems that the discharge step is generally rate determining, and the Butler-Volmer equation is obeyed if the concentration of the supporting electrolyte is sufficiently high. For example, the formation of lithium and sodium amalgams [1] in nonaqueous solvents according to: . . .Li + + e- ⇌ Li(Hg) Na+ = e- ⇌ Cd(Hg) . . . (10.1) obey the Butler-Volrner equation with transfer coefficients that depend on the solvent. On the other hand, the deposition of multivalent ions may involve several steps. Thus, the formation of zinc amalgam from aqueous solutions, with the overall reaction: . . . zn2+ + 2e- ⇌ Zn (Hg) . . . (10.2) occurs in two steps: First, Zn2+ is reduced to an intermediate Zn+ in an electron transfer step, and then the univalent ion is deposited [2]. In contrast, the surface of a solid metal offers various sites for metal deposition. Figure 10.1 shows a schematic diagram for a crystal surface with a quadratic lattice structure. A single atom sitting on a flat surface plane is denoted as an adatom; several such atoms can form an adatom cluster. A vacancy is formed by a single missing atom; several vacancies can be grouped to vacancy clusters. Steps are particularly important for crystal growth, with kink atoms, or atoms in the halfcrystal position, playing a special role. When a metal is deposited onto such a surface, the vacancies are soon filled. However, the addition of an atom in the kink position creates a new kink site; so at least on an infinite plane the number of kink sites does not change, and the current is maintained by incorporation into these sites. Similarly metal dissolution takes place predominantly at half-crystal positions, since the removal of a kink atom creates a new kink site.
Plutonium and Los Alamos
Authors: Graf William L.
Published: November 2020

The plutonium in the Northern Rio Grande is entirely artificial. Small amounts of plutonium may have formed in exceptionally rich uranium deposits in south-central Africa, but for practical purposes, until its manufacture in 1939, the element did not occur in the earth’s environment. Although the detailed story of the origins of plutonium are beyond the scope of this book, a summary of that history does clarify the issues regarding plutonium in the Northern Rio Grande in the late twentieth century. The purposes of this chapter are to review the origins of plutonium and to examine briefly the nature of that element. Modern nuclear physics, which ultimately led to the production of plutonium, began with the publication of the discovery of X-rays by Wilhelm Conrad Röntgen in 1896. His work showed that the physical world was much more complicated than previously thought and that energy could be emitted from substances. In the same year, Henri Becquerel of Paris showed that uranium emitted radiation, and soon thereafter Marie and Pierre Curie coined the term radioactivity to describe the emissions they recorded from two newly discovered elements, radium (named after its radiative properties) and polonium (named after Marie Curie’s home country of Poland). Between 1898 and 1902, Ernest Rutherford of Cambridge University and, later, McGill University explored processes of radioactive decay that generated free electrons (beta radiation) and bursts of energy (gamma radiation) and discovered that some elements changed their basic properties during the emission. Rutherford termed these changes transmutation and laid the philosophical foundations for understanding atomic structure. The transmutation of elements was a significant addition to the rapidly expanding knowledge about the number and types of elements in the natural world. Between 1894 and 1900, William Ramsey enlarged the periodic table with an entire family of inert gases, and by 1903 more than a dozen radioactive elements were known. By 1903, it was obvious that the decay process explained many observed elemental changes: Americans Bertram B. Boltwood and Herbert N. McCoy showed that radium descended from uranium, and Otto Hahn connected several types of thorium.
Photochemistry of van der Waals Complexes and Small Clusters
Authors: Jouvet C. , Solgadi D.
Published: November 2020

In a chemical reaction, the shape of the potential energy surface (PES) dictates the reaction rate and energy disposal in the products. Not only does the dynamics depend crucially upon the features of the surface, but, ultimately one seeks to influence the course of the reaction by preparing selectively certain regions of the surface. For harpooning reactions, the propensity rules for energy disposal in the products (influence of the entrance kinetic energy, effect of the early or late barrier) have been established by Polanyi (1972) and have been used later as guidelines. Here, the surface may easily be modeled in simple terms using long-range electrostatic interaction in the entrance valley. There was, then, need of an experimental method which allows the possibility of observing directly the characteristic regions of this potential energy surface, but also to investigate precisely the surface in other types of reaction. The study of the reactivity of van der Waals complexes is intended to fulfil this purpose. In classical experiments, the surface is obtained by inversion of the experimental data which are differential cross sections and internal energy distribution of the products. This procedure is difficult and not unambiguous. The first step is to determine the correlation between the entrance channel's parameters (kinetic energy, internal energy, angular momentum) and the final states of the products (kinetic energy, internal energy, angular distribution). This requires a precise control of the entrance channel. Therefore, the goal of many experiments is to reduce the initial states to a small subset, and to measure the energy disposal in the products with the greatest accuracy. This was first achieved by controlling the kinetic energy of the reactants in crossed beam experiments. Later, a certain control of the collision geometry was obtained by orienting the molecules or the atomic orbitals in crossed beam experiments or by using prealigned systems in a van der Waals complex: this subject is discussed in Buelow et al. (1986).
Chinese Nutritional Therapy
Authors: Anderson E. N.
Published: November 2020

Chinese nutritional therapy—the use of food as medicine, to treat illness and physical challenge—provides an ideal ground for studies of how people think about their place in the organic world. Unlike many folk systems of medicine, Chinese nutrition has a long written history. Doctors and food experts have devoted much effort to articulating and systematizing a vast amount of information. Much of the data comes from folk observation—the empirical experience of generations of farmers and workers. In Chinese medicine, humans as total persons confront a world of plants, animals, and minerals that have varied medical functions. The line between food and medicine does not exist; all foods have some medical significance, and many medicinal herbs are eaten in enough quantity to count as foodstuffs. Theoretically, there is an infinite number of possible ways of thinking about food and health. The Chinese have constructed a system that represents empirical experience well; fits with their cosmology (the cosmology we have already seen in the preceding chapter); and fits with their views on the individual and society. It is a system that classifies and arranges a great number of facts—statements that are true by the standards of Western laboratory science as well as Chinese experience. It incorporates these truths into a plausible and logical structure, and ties the whole thing to the network of emotions, personal values, and deeply held beliefs that sustain Chinese society. To put it a bit crudely, the system wouldn’t sell if it didn’t work. But, also, it wouldn’t sell if it didn’t fit with the rest of the Chinese system of thought and feeling. In this chapter, I provide a rather thorough account of the traditional Chinese construction of nutritional knowledge. I then show how and why it is logically compelling, given the assumptions of Chinese logic. Finally, I suggest some ways in which it seems to fit well with the Chinese experience of being a person in society. Cultural ecology concerns itself with all human relationships with the environment. Food is one of the field’s main concerns. Foodways provide good examples of demand-driven systems.
Managing the Rainforest: Maya Agriculture in the Town of the Wild Plums
Authors: Anderson E. N.
Published: November 2020

Noemy Chan, a young Maya woman of Mexico, looked up from her cooking and spied her children switching butterflies out of the air with twigs. She immediately dropped her knife, ran to the yard, picked up the butterflies—and made the children eat them. The lesson was explicit: You kill only for food. In the traditional Maya world of the interior rainforests of Quintana Roo, animals are killed only from pressing need. If they are not to be eaten, they can be killed only if they are eating the crops on which humans depend. Ideally, they are slain only when both motives operate. Early one morning I met a family carrying a dead coati in a bag; they said, “It was eating our corn, so we are going to eat it.” In Noemy’s home town, Chunhuhub, even the sale of game is confined to local marketing to other subsistence farmers. The unfortunate habit of poaching game for sale to cities has not—so far—spread into the bush. Noemy and her husband are well off by Mexican standards—he manages heavy equipment for road construction. They saved their money and built an urban-style concrete block house. It stands empty; they live in a traditional Maya pole-and-thatch hut, of a style used continuously for thousands of years in the area. As they correctly point out, the hut is much cooler, cleaner, less damp, and in every way more efficient than the European-style house. The Maya civilization, one of the greatest of the ancient cultures, is by no means dead. Millions of Maya Indians, speaking two dozen related languages, still live in Central America. They practice traditional corn agriculture and maintain many pre-Columbian rituals. Yet they are no more “survivors” of the “past” than are modern Englishmen who still eat bread and beef and worship in the Church of England. Maya civilization is dynamic, living, changing, and, above all, creative. Tough and independent, its bearers have adapted to the modern world; many are doctors, lawyers, and degree-holding professors. They still speak Maya languages, and usually Spanish as well.
Culture: Ecology in a Wider Context
Authors: Anderson E. N.
Published: November 2020

Culture can be seen as a way out of the limits set by information processing. Culture, at its best, institutionalizes sensible, corrective views—usually through the negotiation of various individuals and groups within society. Unfortunately, at its worst, culture institutionalizes the mistakes, and makes them that much harder to correct. The key question is how particular beliefs about resources become accepted as canonical in particular cultures. In other words, the question is, Why do societies—groups of people with specific social organizations—accept particular beliefs as part of their cultures, their accepted repertoires of learned, shared behaviors and texts? Societies and cultures exist only as emergent phenomena, without the flesh-and-blood reality of individual people, but they have their independent structures and dynamics. However, they cannot act or think— only individuals can do that. Conservation is basically about people, not about resources. It is a problem in resource use, but the real problem is not managing the resources but managing the people. We know, more or less, how to manage the resources—at least how to conserve them. The problem is how to motivate people to do it Motivation is an emotional matter. Knowledge is necessary, but knowledge without emotional drive does not produce action. It produces the detached sage, whose knowledge may be potentially useful but whose actions artconfined to arcane trivia. World Bank expert Michael Cernea has recently observed that “social variables are not just an ‘aspect,’ another side of a basically technical issue, but rather lie at the structural core of environmental problems.” Cernea opposes both psychological and economic reductionism in explaining environment use. He points out that social institutions actually direct the managing; we must look at actors, social contracts, cultural and social authority systems, and rules— more or less what Marx called the “relations of production” and the “social superstructure.” This being the case, environmental economists have recently become acutely conscious of social systems and institutions.
In and Out of Institutions
Authors: Anderson E. N.
Published: November 2020

Institutions, including a society’s structure from kinship to kingship, exist for a purpose. That purpose, as Douglass North points out, is often to lower transaction costs. In other words, they make it easier for people to get together to act. (At least, that is what they are supposed to do; sometimes they make it harder.) Usually they are created to make it easier to do something that people were doing already, but often they are created to satisfy a whole new want. By “institutions,” writers like North understand the rules of society, written or unwritten. The actual organizations are specific instances of institutions informing people and situations; the general principles and laws behind the organizations are the institutions. Other writers, of course, use the word “institutions” to include actual organizations, such as prisons and colleges. The discussion that follows is general enough to avoid conflicts over definitions. It is not intended to provide an adequate account of institutions or of environmental economics. It is intended solely to extend my comments on human information processing, and thereby raise some questions about our current economic interpretations. These questions follow from this book’s central premise that humans are emotional, and that emotion often displaces rational calculation. This is, of course, the point classically made by Max Weber; it keeps being rediscovered by institutional economists like Douglas North. The success of a given society at building institutions thus is related to its success at ecological management. This is obvious when the institutions in question are related to conservation. It is not so obvious, but actually more important, when the institutions are more general in scope and purpose, serving the society at large. The most extreme and spectacular case is that of highly centralized, authoritarian polities. It is safe to say that such polities are always a catastrophe for the environment. The farther control gets from the local people who actually benefit or lose by resource management, and the more control is vested in people remote from the scene, the worse the management. These people are decoupled from the results of their actions.
A Summary, and Some Suggestions
Authors: Anderson E. N.
Published: November 2020

The world’s traditional societies have come to some kind of terms with their environments, or they would not have lasted long enough to become “traditional.” Most of them encode in their moral teachings practical wisdom about the environment and the individual’s duty to treat it with respect. These injunctions are lived; they enter daily practice, as when Noemy Chan makes her children eat the butterflies they thoughtlessly kill. They structure whole landscapes, as South China was structured by feng-shui. They stimulate deep personal involvement with actual plant and animal species, as on the Northwest Coast. The common theme of all these traditional resource management ethics is not spiritual harmony with some disembodied and abstracted Nature, but actual personal and emotional involvement with the actual landscape and its nonhuman inhabitants. People interact with their surroundings. In all cultures, these surroundings become meaningful—not just as sources of food and shelter, but as sources of beauty, power, excitement, and other human values. In those cultures that endure and do not collapse, the meanings of nature are bound up in systems of respect and protection. Often, mutual obligations exist between people and the beings or forces they believe to exist in the wild. From the lived experiences of people in cultures around the world, we can extract a number of general principles for environmental management. We can also, mercifully, learn that we need not go to the extreme lengths of ideological reform proposed by some modern environmentalists. Many societies have lived in balance with their environments without devoting their lives to ecology and without invoking elaborate laws. It is not only easier, but apparently more productive, to persuade people to live by a few simple principles of caring for, and enjoying, the world. No group has yet come up with a perfect plan for managing the environment. However, all societies have something to teach. The great benefit of anthropology is that it can bring together the combined wisdom of people from all times and places. Today, we need all the wisdom we can get, and only by pooling a wide range of human experiences can we survive.
The Harm and Benefit Thesis
Authors: Armor David J.
Published: November 2020

Of all the social science theories that have been applied to school desegregation policy, none has a longer or more important history than the harm and benefit thesis. In its simplest form, the thesis holds that school segregation is harmful to the social, psychological, and educational development of children, both minority and white, and that school desegregation is beneficial for undoing or at least ameliorating the damages from segregation and discrimination. While the harm and benefit thesis began as a purely social science theory, its apparent endorsement by the Supreme Court in Brown gave the thesis an enormous boost, elevating it from academic theory to moral authority. From Brown to the present time, the harm and benefit thesis has played a curious and bifurcated role in the evolution of school desegregation policy. Although it began as a social science theory that had apparently found its way into judicial doctrine, its role in the courts soon parted from its role among educators, social scientists, and civil rights groups. On the judicial front, a number of lower court decisions in the early 1970s stressed the harms of school segregation and the benefits of integration remedies. The Supreme Court itself never again explicitly addressed the harm and benefit thesis after Brown, however, and its judicial relevance diminished over the next three decades as the high Court majority restricted the application of Brown to government-enforced school segregation. For this reason many constitutional scholars have long maintained that the psychological harm finding in Brown is not an essential part of constitutional law. To the extent that a harm thesis can be inferred from current judicial doctrine, then, harm arises only if school (or other) segregation is sanctioned by law or official action. For many other actors on the desegregation stage, however, the harm and benefit thesis has had a far broader applicability. During the periods when the earliest formulations began to appear, such as that by Gunnar Myrdal in 1944 or the famous doll studies of Kenneth and Mamie Clark in the late 1930s, most existing segregation was in fact sanctioned by law, and thus most social science research on this issue of necessity reflected the effects of official segregation.
The Future of Desegregation and Choice
Authors: Armor David J.
Published: November 2020

Like most issues stimulated by the civil rights movement over the past four decades, the tangled web of policy questions associated with school desegregation defies easy resolution. The debate over desegregation policy has touched upon many aspects and levels of human society, including values, law, education, and social theory; therefore, arriving a succinct set of policy conclusions, especially one accompanied by substantial consensus, is unrealistic. The debate cannot and should not be reduced simply to a matter of law, to ideological differences, or to disagreements over social science theories. Any attempt to oversimplify the desegregation issue does injustice to those with the greatest stake in its outcome, namely, the students, parents, and educators who reap its rewards and shoulder its costs. Adding to this complexity is the fact that desegregation issues have shifted so much over time that the important policy questions differ from one decade to the next. During the 1950s, the legal and value debate was over compulsory segregation, and social theorists debated whether separate schools were harmful or beneficial for children. During the 1970s, the legal and value debate shifted to compulsory desegregation and whether the benefits of mandatory busing justified its deep divisiveness and its unintended consequences. During the 1990s the debate has shifted once again, this time in several directions. The federal courts struggle with the conditions under which to grant unitary status (and dismissal) to school districts with court-ordered desegregation plans. Surprisingly, considering the great controversy in the 1970s, school boards in the 1990s debate whether to seek unitary status or, if not under court order, to adopt desegregation plans on their own. Civil rights groups are back in court, not only to oppose unitary status but also to demand even broader remedies than those granted during the 1970s. They have requested metropolitan remedies between cities and suburbs, and they have petitioned for racial parity in classrooms, discipline rates, and even academic achievement. Ironically, some of these latest court challenges have come full circle, invoking the psychological harm thesis of Brown that most legal scholars dismissed as irrelevant to the law.
The Scope of Archaeological Geology
Authors: Herz Norman , Garrison Ervan G.
Published: November 2020

Physical scientists—geologists, chemists, physicists—have tried to solve archaeological problems longer than archaeology has existed as a recognized discipline. Few would argue today that scientists should stay away from archaeology and leave it, as it once was, reserved to the humanities. Nevertheless, the union of science and archaeology, although more and more a happy one, has on past occasions resulted in both minor and not-so-minor disasters. To avert disaster, the scientist must appreciate the problems and materials of the archaeologist, and the archaeologist should be knowledgeable about the virtues and pitfalls of scientific methodologies. One of the earliest not-so-minor disasters that resulted from a scientist playing with unfamiliar historical materials occurred in 1818. In response to a plea from the king of Naples, the king of England sent Sir Humphrey Davy to help with the unrolling of papyrus scrolls. The scrolls had been discovered more than 60 years previously in a villa near Herculaneum. A local friar devised a complicated contraption with which he could separate the papyrus sheets, but extremely slowly. At the rate the scrolls were being unrolled, the king of Naples felt it would take several centuries to get the job done. Europe was clamoring to know the contents of the first classical library ever discovered and had also become impatient with the slow progress of the local Neapolitan talent. Sir Humphrey arrived, complete with his portable lab and chemicals. He started work immediately on the scrolls, armed with all the knowledge of early 19th-century science (to which he had contributed a significant portion). Eleven scrolls were selected, and Davy's rapid chemical method was applied. All eleven were destroyed in the process before any attempt could be made to decipher the inscriptions. Whether he was deliberately sabotaged (an English interpretation) or was unlucky in the choice of scrolls submitted for the experiment will never be known. However, the incident serves as a great object lesson for teaching scientists proper humility in approaching archaeological problems. Archaeologists are largely concerned with the esthetics and function of objects and with the cultural and demographic implications of settlements.
Sediments and Soils
Authors: Herz Norman , Garrison Ervan G.
Published: November 2020

Sediments are not soils. Sediments are layered, unconsolidated materials of lithic and/or organic origin. Soils are mixtures of organic and lithic materials capable of supporting plant growth. Sediments that overlie bedrock and cannot support plant growth are termed regolithic. Soils begin as rocks. If they are eroded or altered by diagenetic processes, they can become paleosols. The study of sediments and soils has great importance for the archaeologist because these materials can tell us about the conditions that led to their formation, thus giving much information on paleoenvironments and climate. Not too long ago, the soils of Holocene archaeological sites and the paleosols of more ancient Pleistocene ones were no more than the annoying material concealing the objects of prime interest. More recently, sediments and soils achieved their own importance as the stuff of archaeological geology. In more narrow definitions of the field, they are generally the only subjects of study. The emphasis of archaeological geology is decidedly not the rock. In this text we define archaeological geology in its broadest context such that the linkages between the geological, sedimentological, and cultural (i.e., archaeological) can be explored in all their depth and texture. Ultimately, the linkage of these aspects of earth science and humanity can be categorized under the term ecology, as first coined by Ernst Haeckel in 1866. Here the interrelationships of all areas of the earth system are sought in order to conceptualize stability and change wherever they occur. Sediments and soils typically occur as strata, which are described by principles of superposition, horizontality, continuity, and succession: Superposition: In a series of layers and interfacial features as originally created, the upper units of stratification are younger and the lower are older, for each must have been deposited on, or created by the removal of, a preexisting layer. Original horizontality: Any layer deposited in an unconsolidated form will tend toward a horizontal position. Strata that are found with tilted surfaces were originally deposited horizontally or lie in conformity with the contours of a preexisting basin of deposition.
Instrumental Analytical Techniques
Authors: Herz Norman , Garrison Ervan G.
Published: November 2020

Instrumental analysis has become a mainstay in the study of provenance of artifacts and their materials. A veritable "alphabet soup" of acronyms shorten the often ponderous names of the large number of techniques available today: XRF (x-ray fluorescence), XRD (x-ray diffraction), NAA (neutron activation analysis), AAS (atomic absorption spectroscopy), PIXE (proton-induced x-ray emission), ICP (inductively coupled plasma spectroscopy), FTTR (Fourier transform infrared spectroscopy), EMP (electron microprobe), RIS (resonance ionization spectroscopy), ESR (electron spin resonance), CL (cathodoluminescence spectroscopy), STM (scanning tunneling microscopy), AFM (atomic force microscopy), NSOM (near-field scanning optical microscopy), and SEM/TEM (scanning/transmission electron microscopy).
Metallic Minerals and Archaeological Geology
Authors: Herz Norman , Garrison Ervan G.
Published: November 2020

Economic geology had its inception in the ancient utilization of rocks and minerals. The first economic materials were nonmetallic and include flint, quartz, diabase, rhyolite, obsidian, jade, and other stones, which were sought for weapons, implements, adornment, and even art. Beginning with the Upper Paleolithic Aurignacian period, clay began to be widely used for simple figurines, then brick and finally pottery. S. H. Ball identifies 13 varieties of minerals—chalcedony, quartz, rock crystal, serpentine, obsidian, pyrite, jasper, steatite, amber, jadite, calcite, amethyst, and fluorspar—as economic within the Paleolithic. Add to this list the use of ochres and mineral paints together with nephrite, sillimanite, and turquoise. In the standard reference on the nonmetallic deposits, "Industrial Minerals and Rocks", 6th edition published in 1994, deposits are classified by use and the minerals and rocks described as commodities. The fourteen use groups include such items as abrasives, constructions materials, and gem materials; the 48 commodities include clay, diamonds, feldspar, etc. Metalliferous minerals as ore deposits are unevenly distributed throughout the world. The formation of a mineral deposit is an episode or series of episodes in the geological history of a region and reflects three broad categories: (1) igneous activity, (2) sedimentary processes, and (3) metamorphism. Table 12.1 summarizes general features of the three categories of mineral deposits. Admixtures of metals are by far the most common form of mineral deposits. Gold, silver, and copper occur either as native metals or admixed with other metals and compounds. Most ore deposits are actually mixtures of metals: silver commonly with lead, zinc with cadmium, iron with copper. Many metallic ore deposits are products of igneous activity. Conditions change in the magma chamber as the principal rock-forming minerals crystallize, temperature falls as the magma cools, pressure is lowered as the magma rises in the crust, and volatiles increase in the magma chamber.
Multipole Expansion and Rigid Inclusions
Authors: Phan-Thien Nhan , Kim Sangtae
Published: November 2020

In the previous chapter, we showed how various integral representations arise in the theory of elasticity. All of these representations can be thought of as a surface distribution of various types of singularity solutions. One can go a step further and consider either a finite pointwise or a continuous line, surface, or volume distribution of some suitable singularity solutions; the points on which the singularity solutions reside may not necessarily coincide with points on the surface of the domain. In fact, one may wish to include in the distribution any solution of the Navier equations, not necessarily singular. Such an approach is known as the method of fundamental solution, or simply the singularity method. It has been well developed in Stokes flow, mostly in relation to slender body motion, but to a lesser extent in the theory of elasticity. The method lacks a rigorous theoretical foundation, but is easy to implement numerically, since there is no singular integral to be considered. In the boundary element literature, it is sometimes known as Trefftz method, or the indirect discrete method (Patterson et al.). In this chapter, we will look at some of the elements of the method, namely, the singularity solutions, the far-field expansion (multipole expansion) and some related topics. In the search for suitable solutions of the Navier equations, we may seek guidance from general representations (i.e., general solutions of the Navier equations); the most well known is the Papkovich-Neuber solution.
Completed Double Layer Boundary Element Method
Authors: Phan-Thien Nhan , Kim Sangtae
Published: November 2020

Despite the linearity of the Navier equations, solutions to complex boundaryvalue problems require substantial computing resources, especially in the so-called exterior problems, where the deformation field in the space between the inclusions to infinity must be calculated. In the traditional spatial methods, such as finite difference, finite element, or finite volume, this space must be discretized, perhaps with the help of "infinite" elements or a truncation scheme at a finite but large distance from the inclusions (Beer and Watson, Zienkiewicz and Morgan). There are two important limitations of spatial methods. The first is the mesh generation problem. To be numerically efficient, we must use unstructured mesh and concentrate our effort on where it is needed. Efficient two-dimensional, unstructured, automatic mesh generation schemes exist-one good example is Jin and Wiberg-but unstructured three-dimensional mesh generation is still an active area of research. The second limitation is much more severe: even a moderately complicated problem requires the use of supercomputers (e.g., Graham et al.). Since we are concerned with the large-scaled simulations of particulate composites, with the aim of furnishing constitutive information for modeling purposes, our system will possibly have tens of thousands of particles, and therefore the spatial methods are out of the question. We have seen how the deformation field can be represented by a boundary integral equations, either by a direct method, which deals directly with primitive variables (displacement and trciction) on the surface of the domain, or by the indirect method, where the unknowns are the fictitious densities on the surface of the domain. When the field point is allowed to reside on the surface of the domain, then a set of boundary integral equations results that relates only to the variables on the boundary (displacement and traction, or fictitious densities), and this is the basis of the boundary element method. The boundary is then discretized, and the integrals are evaluated by suitable quadratures; this then leads to a set of algebraic equations to be solved for the unknown surface variables.
A Case Study
Authors: Blum Bruce I.
Published: November 2020

The purpose of this chapter is to evaluate TEDIUM. Evaluation is similar to correctness in that both are always with respect to some external criteria. what criteria should be used for evaluating an environment that develops and maintains software applications using a new paradigm? Clearly, the criteria of the old paradigm (e.g., lines of code, measures of complexity, effort distributed among phases) are irrelevant. In the early days of medical computing, Barnett playfully suggested the following three criteria for evaluating automated medical systems: . . . will people use it? will people pay for it? will people steal it? . . . At the time, the answers to first two questions frequently were negative, and Barnett’s pragmatic approach was intended to prod the field from theory to practice. TEDIUM is used and paid for, but its techniques have not been transported to other environments (i.e., it has not yet been stolen). I console myself by observing that a lack of recognition need not imply an absence of value. The transfer of ideas often is a product of the marketplace, where acceptance depends more on perception than on quantification. As we have seen throughout this book, there can be vast differences between what we care about and what is measurable. Real projects tend to be large, difficult to structure for comparative studies, and highly dependent on local conditions. In contrast, toy studies are easy to control and analyze, but they seldom scale up or have much creditability. How then should I evaluate TEDIUM? I have tried a number of strategies. I have analyzed small projects in detail, I have reported on standard problems comparing TEDIUM data with published results, I have presented and interpreted summary data taken from large projects, I have extracted evaluation criteria from other sources, and I have examined how TEDIUM alters the software process. All of this was summed up in TEDIUM and the Software Process (1990a).
Optical Propagation in Linear Media
Authors: Thomas Michael E.
Published: November 2020

A typical optical system is composed of three basic components: a source, a detector, and a medium in which the optical energy propagates. Many textbooks cover sources and detectors, but very few cover propagation in a comprehensive way, incorporating the latest progress in theory and experiment concerning the propagating medium. This book fulfills that need. It is the first comprehensive and self-contained book on this topic. It is useful reference book for researchers, and a textbook for courses like Laser Light Propagation, Solid State Optics, and Optical Propagation in the Atmosphere.
Experimental Results
Authors: Smith Ronnie W. , Hipp D. Richard
Published: November 2020

One of the main goals of this research was to develop a computational model that could be implemented and tested. Testing could serve at least two purposes: (1) Demonstrate the viability of the Missing Axiom Theory for dialog processing; and (2) Determine the ways that varying levels of dialog control influence the interaction between user and computer. Consequently, an experiment involving use of the system was constructed to test the effects of different levels of dialog control. The format and results of this experiment are reported in this chapter. The following hypotheses are proposed as performance differences by users as they gain experience and have the initiative. • Task completion time will decrease. • The number of utterances per dialog will decrease. • The percentage of “non-trivial” utterances will increase (a nontrivial utterance is any utterance longer than one word). • The average length of a non-trivial utterance will increase. • The rate of speech (number of utterances per minute) will decrease. These hypotheses are consistent with the intuition that as the user has more initiative, the user will put more thought into the process, reducing the rate of interaction. In addition, it is expected that when the user has more initiative, there would be an attempt to convey more detailed information in each non-trivial utterance. Finally, it is also believed that increased user initiative will be more helpful when the user gains experience and has more knowledge about performing the task independent of computer guidance. Two graduate students in computer science volunteered to use the system. Each subject received about 75 minutes of training on the speech recognizer with the 125 word vocabulary. The subjects then participated in three sessions on differing days. Each session consisted of four different problems where each problem consisted of a single missing wire. The results from these subjects tended to support our hypotheses. However, the experimental control for this testing was not well-defined. The two subjects are involved in AI and NL research and consequently have strong preconceptions about NL systems and what constitutes “proper” behavior toward such systems.
Enhanced Dialog Processing: Verifying Doubtful Inputs
Authors: Smith Ronnie W. , Hipp D. Richard
Published: November 2020

Every natural language parser will sometimes misunderstand its input. Misunderstandings can arise from speech recognition errors or inadequacies in the language grammar, or they may result from an input that is ungrammatical or ambiguous. Whatever their cause, misunderstandings can jeopardize the success of the larger system of which the parser is a component. For this reason, it is important to reduce the number of misunderstandings to a minimum. In a dialog system, it is possible to reduce the number of misunderstandings by requiring the user to verify each utterance. Some speech dialog systems implement verification by requiring the user to speak every utterance twice, or to confirm a word-by-word readback of every utterance. Such verification is effective at reducing errors that result from word misrecognitions, but does nothing to abate misunderstandings that result from other causes. Furthermore, verification of all utterances can be needlessly wearisome to the user, especially if the system is working well. A superior approach is to have the spoken language system verify the deduced meaning of an input only under circumstances where the accuracy of the deduced meaning is seriously in doubt, or correct understanding is essential to the success of the dialog. The verification is accomplished through the use of a verification subdialog—a short sequence of conversational exchanges intended to confirm or reject the hypothesized meaning. The following example of a verification subdialog will suffice to illustrate the idea. . . . computer: What is the LED displaying? user: The same thing. computer: Did you mean to say that the LED is displaying the same thing? user: Yes. . . . As will be further seen below, selective verification via a subdialog results in an unintrusive, human-like exchange between user and machine. A recent enhancement to the Circuit Fix-it Shop dialog system is a subsystem that uses a verification subdialog to verify the meaning of the user’s utterance only when the meaning is in doubt or when accuracy is critical for the success of the dialog. Notable features of this new verification subsystem include the following.
The Nature We Have Lost
Authors: Worster Donald
Published: November 2020

Nostalgia runs all through this society—fortunately, for it may be our only hope of salvation. My own version, which I probably share with a few million others, takes me back to walk in pristine natural places on this continent. I dream of traveling with our second native-born naturalist, William Bartram (his father John was the first), a slightly daft Pennsylvania Quaker who botanized from the Carolinas down into Florida in the early 1770s. I would travel with him, “seduced by ... sublime enchanting scenes of primitive nature,” through aromatic groves of magnolia, sweet gum, cabbage palmetto, loblolly pine, live oak, the roaring of alligators in our ears. I would gaze with Thomas Jefferson through his elegant white-framed windows at Monticello toward the Blue Ridge Mountains, speculating about the prodigious country stretching west. Best of all, I imagine entering that west with Lewis and Clark in 1804–5, standing beside them on Spirit Mound in present-day South Dakota, beholding, as Clark put it in his execrable spelling, “a most butifull landscape; Numerous herds of buffalow were Seen feeding in various directions; the Plain to North N. W. & N.E. extends without interuption as far as Can be seen.” And I think what it must have been like for them warping and poling up the muddy Missouri River, penetrating farther into the vast open country of the unplowed, unfenced prairies when wolves still howled in the night; of heading into “the great unknown,” panting over the unpainted, unmined, unskiied Rocky Mountains and rafting down the uncharted, undammed Columbia to the gray-green drizzly shore of the Pacific Ocean. How much has been lost in our short years as a nation, how much have we to be nostalgic about. In the beginning of white discovery North America must have been a glorious place, brimming with exquisite wild beauty, offering to agriculturists some of the earth's richest soils, incredible stands of trees, booty on booty of mineral wealth. Think for a moment of the infinitude of animals that once teemed but are now diminished or gone. In the most comprehensive, detailed analysis yet offered, Frank Gilbert Roe estimated that forty million bison roamed the continent as late as 1830.
Toward Unity among Environmentalists
Authors: Norton Bryan G.
Published: November 2020

Today, six out of ten Americans describe themselves as "active" environmentalists or as "sympathetic" to the movement's concerns. The movement, in turn, reflects this millions-strong support in its diversity, encompassing a wide spectrum of causes, groups, and sometimes conflicting special interests. For far-sighted activists and policy makers, the question is how this diversity affects the ability to achieve key goals in the battle against pollution, erosion, and out-of-control growth. This insightful book offers an overview of the movement -- its past as well as its present -- and issues the most persuasive call yet for a unified approach to solving environmental problems. Focusing on examples from resource use, pollution control, protection of species and habitats, and land use, the author shows how the dynamics of diversity have actually hindered environmentalists in the past, but also how a convergence of these interests around forward-looking policies can be effected, despite variance in value systems espoused. The book is thus not only an assessment of today's movement, but a blueprint for action that can help pull together many different concerns under a common banner. Anyone interested in environmental issues and active approaches to their solution will find the author's observations both astute and creative.
Final Thoughts
Authors: Hoyt Douglas V. , Shatten Kenneth H.
Published: November 2020

In 1872 Meldrum found an apparent relationship between the number of Indian cyclones and the solar cycle. If valid, this strong relationship has significant social and economic impacts. Shipping disasters might be avoided, agricultural yields predicted, and famines prevented. The implications were so important that Meldrum’s observation inspired several programs to make detailed solar observations. In 1874 the Royal Greenwich Observatory started detailed observations of sunspot areas and positions, a program that continued until 1976. Ironically, in 1976 Jack Eddy published his paper “The Maunder Minimum” that greatly revived interest in sun/climate studies. Yet just when the best sunspot position and area measurements could be made and analyzed with modern spacecraft data, making them more essential than ever, this measurement program ceased. For more than 50 years, Charles Greeley Abbot measured the solar irradiance from mountain tops around the world. Despite his best efforts, removing atmospheric effects from his measurements proved virtually impossible. Separating solar changes from atmospheric changes to find the actual solar behavior proved extremely difficult. Only satellite measurements could fulfill Abbot’s dream of truly accurate solar-irradiance monitoring. Abbot’s dream became reality in 1978 with the launch of the Nimbus-7 satellite. Unfortunately, Abbot died in 1973 at the age of 101. Many controversies and ironies exist in the sun/climate field. One additional irony worth mentioning is the claim by Dove and Maury in the last century that the sun’s radiant output remains constant and therefore plays no role in climate change. What is surprising about these findings is that although their work influenced other scientists, these men were not solar physicists but oceanographers, yet they felt free to define solar behavior. Solar physicists have never been highly confident about the sun’s constancy, since the sun shows some variability wherever it is observed. The first argument points out that the sun’s brightness varies by a few tenths of 1% over the solar cycle, and virtually all present-day climate models suggest that the effects on the Earth will be small. At best, Earth temperature changes will amount to only a few hundredths of a degree and will be difficult to detect.