bluuebunny/crossref_metadata_2025 huggingface dataset:
Networks Having Multimodal Chain-Length Distributions
Authors: Erman Burak , Mark James E.
Published: November 2020

As was mentioned in chapter 10, end-linking reactions can be used to make networks of known structures, including those having unusual chain-length distributions. One of the uses of networks having a bimodal distribution is to clarify the dependence of ultimate properties on non-Gaussian effects arising from limited-chain extensibility, as was already pointed out. The following chapter provides more detail on this application, and others. In fact, the effect of network chain-length distribution, is one aspect of rubberlike elasticity that has not been studied very much until recently, because of two primary reasons. On the experimental side, the cross-linking techniques traditionally used to prepare the network structures required for rubberlike elasticity have been random, uncontrolled processes, as was mentioned in chapter 10. Examples are vulcanization (addition of sulfur), peroxide thermolysis (free-radical couplings), and high-energy radiation (free-radical and ionic reactions). All of these techniques are random in the sense that the number of cross-links thus introduced is not known directly, and two units close together in space are joined irrespective of their locations along the chain trajectories. The resulting network chain-length distribution is unimodal and probably very broad. On the theoretical side, it has turned out to be convenient, and even necessary, to assume a distribution of chain lengths that is not only unimodal, but monodisperse! There are a number of reasons for developing techniques to determine or, even better, control network chain-length distributions. One is to check the “weakest link” theory for elastomer rupture, which states that a typical elastomeric network consists of chains with a broad distribution of lengths, and that the shortest of these chains are the “culprits” in causing rupture. This is attributed to the very limited extensibility associated with their shortness that is thought to cause them to break at relatively small deformations and then act as rupture nuclei. Another reason is to determine whether control of chain-length distribution can be used to maximize the ultimate properties of an elastomer. As was described in chapter 10, a variety of model networks can be prepared using the new synthetic techniques that closely control the placements of crosslinks in a network structure.
Different Spatial Scales of Natural Selection and Gene Flow: The Evolution of Behavioral Geographic Variation and Phenotypic Plasticity
Authors: Thompson Daniel B.
Published: November 2020

The environmental variables hypothesized to cause behavioral adaptation are distributed across a wide array of spatial scales, from local variation in factors such as food sources and territorial encounters to regional or continental variation in factors such as seasonality and the presence of predators. Geographic variation in behavior, the topic of this book, is just one of the potential evolutionary responses to environmental variation. Because behavioral divergence among populations generated by disparate natural selection can be counterbalanced by the homogenizing influence of gene flow, adaptive geographic variation can evolve only if the spatial scale of variation in natural selection is greater than the scale of gene flow (Endler 1977, Slatkin 1978). If geographic variation does not evolve because the spatial scale of selection is smaller than the scale of gene flow, populations may instead evolve adaptive phenotypic plasticity (Bradshaw 1965); the expression, by a single genotype, of different fitness-enhancing phenotypes in different environments. Because the same evolutionary processes operating on different spatial scales can generate behavioral geographic variation, behavioral phenotypic plasticity, or geographic variation in phenotypic plasticity, I devote this chapter to development of a hierarchical perspective tor studying environmental variation and behavioral evolution. This perspective emphasizes the shared evolutionary processes and research methodologies common to different levels of spatial variation, such as the balance of gene flow, natural selection, and genetic drift, the relationship between environmental patch size and local adaptation, and the effects of historical contingencies and genetic constraints on behavioral adaptation and phenotypic plasticity. In what follows, I review behavioral research in two unrelated taxa to illustrate the range of possible evolutionary responses to different patterns of environmental variation. First, I discuss different spatial scales of adaptation in the climbing behavior of deer mice (Peromyscus maniculatus) and provide a hierarchical analysis of the effects of natural selection, genetic drift, and gene flow. Second, I discuss diet-induced phenotypic plasticity in the feeding behavior of acridid grasshoppers (Melanoplus femurrubrum and M. sanguinipes) and the evolution of behavioral norms of reaction in response to local spatial and temporal variation in plant environments.
Geographic Variations on Methodological Themes in Comparative Ethology: A Natricine Snake Perspective
Authors: Burghardt Gordon M. , Schwartz James M.
Published: November 2020

The most distinctive and characteristic emphasis of early ethology was also what set it off from other post-Darwinian studies of animal behavior. This was the view that behavior varied among species in the same way as did morphological characters and that behavioral differences were as much a product of the evolutionary drama as were the characters that could be measured in museum collections (Tinbergen 1960, Lorenz 1981, Burghardt 1985, Burghardt and Gittleman 1990, Gittleman and Decker 1994). The logical extensions of this view were that behavioral phenotypes could be used in reconstructing phylogenetic histories, that the evolution of behavioral phenotypes could be studied in the same way as the evolution of other classes of traits, and that many of the behavioral differences among taxa reflected underlying genetic differentiation at both the species (Hinde and Tinbergen 1958) and population (Foster and Cameron 1996) levels. Behavior may also initiate evolutionary changes in other attributes of organisms (Mayr 1960, 1965, Wcislo 1989, Gittleman et al. 1996). Although the role of genes in behavioral determination remained controversial for years (see Gottlieb 1992, de Queiroz and Wimberger 1993 for current critiques), many behavior patterns have proven heritable (Mousseau and Roff 1987; papers in Boake 1994b). Indeed, some complex, “species-typical” behavior patterns are performed normally without opportunity for learning (Lorenz 1965). Such behavior patterns can be expressed early or late in development (Lorenz, 1981). At the other extreme, many complex behavioral phenotypes are learned with only slight, if any, genetically based predisposition to perform particular behavior patterns. Between these extremes is a diversity of interactions between genes and environment, including imprinting and complex developmental trajectories produced by interactions between neural development and experience. Many of the currently interesting and controversial questions in the nature–nurture debate do not center around species-typical behavior patterns. Instead, they concern the nature of genetic differences among individuals and populations in the performance of particular behavior patterns and in the ability to modify their performance with experience. Thus the problem must be conceptualized as one in which the interactions of specific genetic constitutions with specific environmental contexts need to be evaluated.
Geographic Variation in Behavior of a Primate Taxon: Stress Responses as a Proximate Mechanism in the Evolution of Social Behavior
Authors: Boinski Sue
Published: November 2020

Temperament is a complex behavioral trait that describes characteristic patterns of response to environmental, particularly social, conditions and perturbations. Disparities in the tendency to approach or avoid novelty or readiness to engage in aggressive interactions have been documented in comparisons between species (Christian 1970), subspecies (Gonzalez et al. 1981), populations within species (Champoux et al. 1994), inbred lines of laboratory animals (Scott and Fuller 1965), domesticated versus wild populations (Price 1984), and individuals within a species (Benus et al. 1992). Differences in physiological stress response systems (Selye 1937) are commonly identified as an important proximate mechanism underlying these temperament differences (Huntingford and Turner 1987, Kagan et al. 1988). Social systems of animals are perceived as emerging from relationships between individuals (Hinde 1983). Individual interactions, in turn, are hypothesized to reflect individual behavioral strategies which maximize inclusive fitness (Silk 1987). Selection on a physiological system, which can dramatically affect the pattern and outcomes of individual interactions, could produce evolutionary change in social organization and social behavior. Many workers explicitly suggest that temperament differences among primate species are adaptive in many instances, yet admit that the specific ecological and social selection pressures to which the neuroendocrine system is responding are often unclear (Thierry 1985, Clarke et al. 1988, Richard et al. 1989). Species-level comparisons have not offered many testable comparative models, probably because of confounding effects such as large phylogentic distances or uncertain phylogeny, inadequate knowledge of ecological and social conditions in the wild, drift, and convergent evolution. In short, little progress has been made toward understanding the evolution of stress-response patterns in primates. In this chapter I suggest that comparisons of geographically and genetically separated primate populations or subspecies may be an alternative and more successful approach to addressing the evolution of stress responses and the disparate social behaviors that result. Population and geographic comparisons are likely to be profitable for three reasons: (1) comparisons are less likely to be confounded by phylogenetic disparities (Arnold 1992), (2) the factors imposing different selective regimes among localities can perhaps be more readily identified, (3) hypothesis testing may be facilitated because populations suitable for testing a model will be easier to identify than new species.
Comparisons of Cities
Authors: Crouch Dora P.
Published: November 2020

A brief reprise of the geological aspects, organization, physical constraints, and appearance of each city will remind us of their common and unique features. Then we can compare them by groups linked by research questions. Agrigento is built on two ridges of 120 and 320–390 m, setting generous limits not yet filled by the modern city. A plain extends from the lower ridge south to the sea. Vistas were provided along contours and across elevations. Grouping the public buildings on stony ridges, with temples above and below and government structures along the west side, made economic and aesthetic sense. Landslides provide important clues to the nature of the hill the city is built on, and they correlate with occupation of various parts of the site. Additionally, the water system shows unexpected correlation with the families of discontinuities in the stone rather than the surface grid of the streets (Ercoli and Crouch 1998; Crouch 1989). Morgantina stretches along a ridge about 600 m in elevation. The agora most clearly reveals the interface of urban design and geology. Sanctuaries and fountains were the focus during the fifth century B. C. E. In the third century, modest but elegant new architecture (theater, great steps, flanking stoas, fountains, sanctuary) combined with pragmatic engineering as framework and connector between points of observation. Morgantina had one aqueduct, from the springs that later supplied Aidone. The site has numerous springs although some are now dry or give less than 1 l/s. Yet, during the third century B. C. E. when the population was at its maximum, the aquifer was also at maximum, and higher springs were fed from it more amply than at present. Improper management of water resources likely hastened the demise of the town after the Roman conquest. At the turn of the era, the shift from small rural towns to great landed estates as centers of population affected Morgantina strongly. Deforestation of the hills and mountains for fuel and building materials could have resulted in desiccation, with climate change a related factor. Occupation by the Hispanii (Spanish veterans) who replaced the Hellenized Sicilians after 211 B. C. E. coincided with a negative water balance.
1991
Authors: Babbitt Milton
Published: November 2020

I am grateful and flattered to have had my talk . . . included under the ongoing rubric of “A Life of Learning,” but in all accuracy and necessary realism I must be permitted the protective sub-rubric of “A Composer of a Certain Age,” for how might a composer justify his presence before learned representatives of learned bodies, when the very term learned has appeared and disappeared in the history of music only in the most apologetic and fugitive of roles, in such expressions as learned writing or—more specifically— learned, counterpoint, usually with the intimation of the anachronistic, the factitious, and—even—the jejune? There does appear to have been a fleeting moment or so in eighteenth-century France when the term learned was invoked to characterize a “taste” distinguished from the “general.” Apparently, compositions were deemed to be “learned” if it was thought that their understanding demanded some musical knowledge. But this elitist distinction did not, could not, survive the guillotine, and never was to be reheaded, certainly not with the subsequent and continuing triumph of what Goodman has called the Tingle—Immersion theory, which—when applied to music—demands that music be anyone’s anodyne, a non-habit-forming nepenthe. I could dig even deeper historically and dare to remind you that, in the medieval curriculum, music was a member of the quadrivium, but that curriculum, like so many demanding curricula after it, has long since been banished. And, in any case consider the company that music kept in the quadrivium: arithmetic, geometry, and astronomy. If that curriculum had survived, music would be burdened further with guilt by association, because—for reasons apparently more sociological than methodological—there is no characterization that guarantees music more immediate, automatic, and ultimate derogation and dismissal than mathematical, thereby joining learned and, above all, academic. But it is as academics that we join here. ... I trust it does not come as a surprise, or as an unpleasant embarrassment, or as further evidence of the Greshamization of the university, to learn that there are composers in your very midst on your faculties.
Correspondence Analysis In Heavy Mineral Interpretation
Authors: Tourenq J. , Rohrlich V.
Published: November 2020

Correspondence analysis, a non-parametric principal component analysis, has been used to analyze heavy mineral data so that variations between both samples and minerals can be studied simultaneously. Four data sets were selected to demonstrate the method. The first example, modern sediments from the River Nile, illustrates how correspondence analysis brings out extra details in heavy mineral associations. The other examples come from the Plio-Quaternary "Bourbonnais Formation" of the French Massif Central. The first data set demonstrates how the principal factor plane (with axes 1 and 2) highlights relationships between geographical position and the predominant heavy mineral association (metamorphic minerals and zircon), suggesting the paleogeographic source. In the second set, the factor plane of axes 1 and 3 indicates a subdivision of the metamorphic mineral assemblage, suggesting two sources of metamorphic minerals. Finally, outcrop samples were projected onto the factor plane and reveal ancient drainage systems important for the accumulation of the Bourbonnais sands. Statistical methods used in interpreting heavy minerals in sediments range from simple and classical methods, such as calculation of means and standard deviations, to the calculation of correspondences and variances. Use of multivariate methods is increasingly frequent (Maurer, 1983; Stattegger, 1986; 1987; Delaune et al., 1989; Mezzadri and Saccani, 1989) since the first studies of Imbrie and vanAndel (1964). Ordination techniques such as principal component analysis (Harman, 1961) synthesize large amounts of data and extract the most important relationships. We have chosen a non-parametric form of principal component analysis called correspondence analysis. This technique has been used in sedimentology by Chenet and Teil (1979) to investigate deep-sea samples, by Cojan and Teil (1982) and Mercier et al. (1987) to define paleoenvironments, and by Cojan and Beaudoin (1986) to show paleoecological control of deposition in French sedimentary basins. Correspondence analysis has been used successfully to interpret heavy mineral data (Tourenq et al, 1978a, 1978b; Bolin et al, 1982; Tourenq, 1986, 1989; Faulp et al, 1988; Ambroise et al, 1987). We provide examples of different situations where the method can be applied. We will not present the mathematical and statistical procedures involved in correspondence analysis, but refer readers to Benzécri et al.
Automated Correlation Based On Markov Analysis Of Vertical Successions And Walther's Law
Authors: Collins D.R. , Doveton J.H.
Published: November 2020

Walther's Law of Facies (1894) states that facies overlying one another comformably were formed in geographically contiguous environments. This vertical-lateral linkage is the basis for our automated method of stratigraphic correlation. The probabilities of vertical adjacency of different lithologies are estimated by embedded Markov chain analysis of sequences to be correlated. These probabilities are transformed to dissimilarities and used as elements within a dynamic programming sequence comparison. Trajectory tracking of cumulative thicknesses between the two sequences provides an auxiliary criterion to incorporate factors of sedimentation rate and compaction. Stratigraphic correlation is simultaneously simple and complex. The operation is fundamentally one of pattern recognition, whose principles can be grasped easily by any geology student. One source of complexity is caused by the fact that most successions are composed of a relatively small number of distinctive rock types. Within each succession, they are ordered as a linear chain in which loosely repetitive sequences are often perceived as "cycles" or "rhythms." As a result, the correlation between two adjacent successions may be ambiguous, so that several competing alternatives may be equally valid candidates for the "true" correlation. The situation is made still more disma! by the knowledge that erosional events may have removed entire stratigraphic segments and that periods of non-deposition may have caused gaps. In the opinion of Ager (1973), the gap is more important than the record. Even if a "complete" lithology record were available, it is unlikely that the successions in two separate locations would be identical. Lateral facies changes result in differences of lithology within correlative intervals. Equivalence or "similarity" of rock type is not the only criterion used in correlation. Thicknesses are a secondary source of information for correlation decisions. Similarity in thickness of equivalent lithologies between successions often implies a greater likelihood of their correlation. However, exceptions to this rule commonly are observed in the lateral thinnings and thickenings caused by both lateral facies changes and differential compaction. The simpler aspects of correlation suggest that practical automated correlation procedures are both feasible and desirable. Even if programmed decisions cannot be characterized absolutely as "objective," they can at least be made consistent.
Quantitative Genetics In Paleontology: Evolution In Tertiary Ostracoda
Authors: Reyment Richard A. , McKenzie K.G.
Published: November 2020

The applied science of quantitative genetics has a fairly long history in animal husbandry. In its original form, as developed mainly in the hands of D.S. Falconer, there was little obvious connection to the study of evolutionary change in the morphology of fossil species (a summary is given in Falconer, 1981). However, Lande (1976, 1979) derived several generalizations that were aimed at adapting existing theory and method to the study of evolution in the phenotype. The analysis of shape is a subject that has preoccupied quantitative biologists and biometricians for almost all of our present century. Legion are the methodologies that have been put forward, but the first; real solution is quite recent and is due to F.L. Bookstein. A complete account of the history and current state of the art has appeared recently (Bookstein, 1991), and there is a paleontologically oriented summary in Chapter 4 of Reyment (1991). Topics considered in the present brief overview are: 1. Evolution in morphological characters of fossil species related to hypotheses of selection and random genetic drift; 2. Evolution in shape divorced from the effects of size; 3. Erection of a valid hypothesis for the analysis of morphological changes in time. An important conceptual basis for the application of quantitative genetics to evolutionary biology is that of phenotypic plasticity (Schmalhausen, 1949), i.e., the expression of ecophenotypy. It, is a necessary step in an analysis to distinguish between variation arising solely from internal, genetic causes and variation caused by morphological responses to ecological factors. Evolution in the phenotype is most easily approached via consideration of a single distance measure, even though this is not realistic since a meaningful evaluation of an evolutionary sequence on just one character cannot tell us very much. For demonstration purposes we will use a length or distance measured between two diagnostic locations on the organism and study changes by means of models for assessing selection and drift. In the accompanying example we use as our characteristic the height of the carapace of Tertiary ostracodes, that is, the distance between the cardinal angle and the base of the anteroventral rounding.
Amplitude And Phase In Map And Image Enhancement
Authors: Robinson Joseph E.
Published: November 2020

Many geographic information systems (GIS) and computer mapping packages for graphic display provide data enhancement routines that utilize spatial filtering and may even include sample filter operators. With care, spatial filtering or convolving a filter with string or gridded data can be very effective in enhancing digital information. Filtering is intended to highlight specific features, remove unwanted noise or restore an image. The filtered output may be smoothed, it may portray features of a specific size, or it may subject data to mathematical operations. Results depend on the form of the filter operator, Fourier analysis of the filter operator produces frequency and phase diagrams that describe the effect the filter will have on the input data. These diagrams indicate how the component frequencies in the input data will be altered by the filter. Phase relates to the position of contained features, and amplitudes are responsible for feature definition. Derivative filtering may alter both phase and amplitude and completely change the appearance of the output. Spatial filtering can be very effective, however the interpreter must exercise great care selecting suitable filters. Fourier analysis can aid in design of a suitable filter and in the resultant evaluation. Examples herein describe some common three-value filters for string data and three-by-three matrix filters for grid and raster data. Digital spatial filters are arrays of values with the same form and interval as the original numeric data set (e.g., Robinson and Treitel, 1969). Filters may be strings of one-dimensional values, two-dimensional gridded data sets, or even multi-dimensional data. Spatial filters to be used with digital data sets can be designed and evaluated in either the spatial or the frequency domain. Similarly, line, map, and image data can be transformed and viewed in both domains. Fourier analysis is the bridge between the two domains (Cooley and Tukey, 1965; Gentleman and Sande, 1966; Robinson and Cohn, 1979; Sondegard, Robinson and Merriam, 1989). The filtering operation can be carried out in either domain by convolution in the spatial domain or by multiplication in the frequency domain. Convolution is the Fourier transform of multiplication.
An Executable Notation, With Illustrations From Elementary Crystallography
Authors: Mclntyre Donald B.
Published: November 2020

Elementary crystallography is an ideal context for introducing students to mathematical geology. Students meet crystallography early because rocks are made of crystalline minerals. Moreover, morphological crystallography is largely the study of lines and planes in real three-dimensional space, and visualizing the relationships is excellent training for other aspects of geology; many algorithms learned in crystallography (e.g., rotation of arrays) apply also to structural geology and plate tectonics. Sets of lines and planes should be treated as entities, and crystallography is an ideal environment for introducing what Sylvester (1884) called "Universal Algebra or the Algebra of multiple quantity." In modern terminology, we need SIMD (Single Instruction, Multiple Data) or even MIMD. This approach, initiated by W.H. Bond in 1946, dispels the mysticism unnecessarily associated with Miller indices and the reciprocal lattice; edges and face-normals are vectors in the same space. The growth of mathematical notation has been haphazard, new symbols often being introduced before the full significance of the functions they represent had been understood (Cajori, 1951; Mclntyre, 1991b). Iverson introduced a consistent notation in 1960 (e.g., Iverson 1960, 1962, 1980). His language, greatly extended in the executable form called J (Iverson, 1993), is used here. For information on its availability as shareware, see the Appendix. Publications suitable as tutorials in , J are available (e.g., Iverson. 1991; Mclntyre, 1991 a, b; 1992a,b,c; 1993). Crystals are periodic structures consisting of unit cells (parallelepipeds) repeated by translation along axes parallel to the cell edges. These edges define the crystallographic axes. In a crystal of cubic symmetry they are orthogonal and equal in length (Cartesian). Those of a triclinic crystal, on the other hand, are unequal in length and not at right angles. The triclinic system is the general case; others are special cases. The formal description of a crystal gives prominent place to the lengths of the axes (a, b, and c) and the interaxial angles ( α, β, and γ). A canonical form groups these values into a 2 x 3 table (matrix), the first row being the lengths and the second the angles.
Models and representations
Authors: Schenck Douglas , Wilson Peter
Published: November 2020

A model is a representation of something; it is an abstraction. The thing being modeled need not be real — think of plastic models of the starship Enterprise. In this case the thing is imaginary while the model is real. Models are typically built to aid understanding. Also, because they are abstractions that omit inessential details, they are often easier to construct and manipulate than the thing they represent. However, as we shall see, an information model is not necessarily simple, either to create or to manipulate. We distinguish two sorts of model here, namely a conceptual model and a concrete model. Definition 4 A conceptual information model is independent of any particular instantiation form. Definition 5 A concrete model is an information model that is specialized to take account of a particular instantiation method. (This is what is typically known as a data model.) An information (data) model may be instantiated or populated to represent collections of particular ideas, facts or processes. Definition 6 An instantiated model consists of the data that represents instances of the things defined in an information model. We are principally concerned with conceptual information models. A conceptual model is a view about real world information and is itself, therefore, communicable information. The model needs to be organized in such a manner to aid understanding by the recipient, which will essentially be a human as opposed to a computer system; even if the intended recipient is a software system this is still a human artifact. Before examining ways of representing models it is useful to look briefly at some of the methods that we humans use to organize our thoughts. There are some organizing principles and concepts that we seem to use time after time, whether consciously or unconsciously. We tend to group things into categories or classes. Each member of a category has some aspects that are common to other members and some individual aspects. For example, we can talk about vehicles in general with one common aspect being that a vehicle provides a means of transportation. Within the general vehicle class we might split it up into sub-categories of truck, bus and car.
The modeling process
Authors: Schenck Douglas , Wilson Peter
Published: November 2020

Each information model is unique, as is the process of developing that model. In this Chapter we provide some broad guidelines to assist you in creating a quality model. We are basically recommending a policy of progressive refinement when modeling but the actual process usually turns out to be iterative. So, although one might start out with good intentions of using a top-down approach, one often ends up with a mixture of top-down, bottom-up, and middle-out strategies. The recommendations are principally cast in the form of check lists and give a skeleton outline of the process. Chapter 4 provides a complete worked example which puts some flesh on the bones. An information model may be created by a single person, given sufficient knowledge, or preferably and more likely by a team of people. An information model represents some portion of the real world. In order to produce such a model an obvious requirement is knowledge of the particular real world aspects that are of interest. People with this knowledge are called domain experts. The other side of the coin is that knowledge of information modeling is required in order to develop an information model. These people are called modeling experts. Typically, the domain experts are not conversant with information modeling and the modeling experts are not conversant with the subject. Hence the usual need for at least two parties to join forces. Together the domain and modeling experts can produce an information model that satisfies their own requirements. However, an information model is typically meant to be used by a larger audience than just its creators. There is a need to communicate the model to those who may not have the skills and knowledge to create such a model but who do have the background to utilize it. Thus the requirement for a third group to review the model during its formative stages to ensure that it is understandable by the target audience. This is the review team who act somewhat like the editors in a publishing house, or like friendly quality control inspectors.
Parallel Prefix Algorithms On Linked Lists
Authors: Lakshmivarahan S. , Dhall Sudarshan K.
Published: November 2020

This Chapter describes algorithms for computing prefixes/suffixes in parallel when the input data is in the form of a linked list. Developments in this Chapter complement those in Chapter 3. We begin by defining a version of the prefix problem called the list ranking problem. Let < N > = {1,2, • • • , N} and L be a list of size N. For each i ∈ < N >, the node i in L contains two types of information: the value v(i) of node i, and the successor s(i) of node i. Clearly, s(N) = 0. A linked list may conveniently be represented as a directed, labeled graph G(V, E), where V =  and . . . E = { (i, j ) | j = s(i), i, j ∈ V }, and v (i) denotes the value for node i.
Bounding Fan-Out In Parallel Prefix Circuits
Authors: Lakshmivarahan S. , Dhall Sudarshan K.
Published: November 2020

The depth-optimal and (size + depth)-optimal circuits described in Chapters 5 and 6 have the property that they have a constant or fixed fan-in but unbounded fan-out. From practical considerations, it is desirable to construct circuits with bounded fan-out as well. In this Chapter, we first describe general methods for bounding fan-out in circuits, and then demonstrate an application of these techniques to obtain parallel prefix circuits with fixed fan-in and fixed fan-out. However, bounding fan-out increases the size and depth. The principal result of this Chapter is to derive bounds on the increase in the size and depth resulting from fixing the fan-out. A glance at the structure of the d-optimal and (s, d)-optimal circuits defined in Chapters 5 and 6 reveals that these circuits have unbounded fan-out (that is, fan-out is a function of N, the number of inputs). However, in practice, such as, in VLSI implementation, for practical reasons stemming from power, noise, and reliability considerations, the fan-out has to be limited to a small, fixed number, for instance, k (such as 2 or 3). We first describe an optimal method for bounding fan-out and then apply it to prefix circuits. To understand the effect of limiting the fan-out, consider an example of a node a in Figure 1, with fan-out 9. This can be thought of as a 9-ary tree with a as its root, and bi, 1 ≤ i ≤ 9 as the leaves. Suppose that we have to limit the fan-out to 3. That is, we have to replace the 9- ary tree in Figure 1 by a 3-ary tree with a as its root and bi, 1 ≤ i ≤ 9, as the leaves with the constraint that the values of the leaves remain unchanged. One such tree is given in Figure 2. Clearly, restricting the fan-out simultaneously increases the depth and the size of the circuit. In this example, the size is increased by 3 and the depth by 1.
Causing Harm: Epidemiological and Physiological Concepts of Causation
Authors: Schaffner Kenneth F.
Published: November 2020

In this chapter I shall examine the relations between what appear to be two somewhat different concepts of causation that are widely employed in the biomedical sciences. The first type is what I term epidemiological causation. It is characteristically statistical and uses expressions like "increased risk" and "risk factor." The second concept is more like the form of causation we find in both the physical sciences and everyday life, as in expressions such as "the increase in temperature caused the mercury in the thermometer to expand" or "the sonic boom caused my window to break." In the physical and the biological sciences, such claims are typically further analyzed and explained in terms of underlying mechanisms. For example, accounts in the medical literature of cardiovascular diseases associated with the ischemic myocardium typically distinguish between the risk factors and the mechanisms for these disorders (Willerson 1982). Interestingly, both concepts of causation have found their way into the legal arena, the first or epidemiological concept only relatively recently in both case law and federal agency regulatory restrictions. The second, perhaps more typical, notion of causation has turned out to be not so simple on deeper analysis and led Hart and Honoré, among others, to subject the notion to extensive study in their classic book Causation in the Law. In another paper (Schaffner 1987), I examined some of these issues, in particular the epidemiological concept of causation as it might apply to recent DES cases such as Sinddl and Collins. Reflections on the Sindell case and on one of its legal precedents, the Summers v. Tice case, led Judith Jarvis Thomson to introduce a distinction between two types of evidence that might be adduced to support a claim that an agent caused harm to a person. The two types of evidence parallel the distinction between these two concepts of causation, and 1 shall introduce them by means of a particularly striking example originally credited to David Kaye (Kaye 1982).
Plutonium and the Rio Grande
Authors: Graf William L.
Published: November 2020

The first atomic bombs were constructed at the Los Alamos National Laboratory, where lab workers disposed of waste plutonium in nearby canyons leading to the Rio Grande. Today, the environmental consequences are just beginning to be understood as scientists examine the effects created by past mishandling of one of the most toxic chemical wastes known. Written in an engaging, accessible style, Plutonium and the Rio Grande is the first book to offer a complete exploration of this environmental history. It includes an explanation of what plutonium is, how much of it was released by the Los Alamos workers, and how much entered the river system directly from waste disposal and indirectly, as a result of atomic bomb fallout. The book includes extensive appendices, maps, diagrams, and photographs. Environmental managers, ecologists, hydrologists and other river specialists, as well as concerned general readers will find the book readable and informative.
Plutonium in the Rio Grande System
Authors: Graf William L.
Published: November 2020

The water, sediment, landform, and vegetation systems of the Northern Rio Grande provide the environmental framework within which plutonium moves and is stored. Plutonium enters the Northern Rio Grande from two sources: atmospheric fallout and releases from operations of Los Alamos National Laboratory that enter the main stream by transport through Los Alamos Canyon. This chapter describes the nature and timing of plutonium loading in the river’s sediment system as a means of identifying those years when sedimentation is likely to have accumulated those deposits with the highest concentrations of plutonium. This chapter also discusses plutonium in river water, sediments in transit, and sediments deposited along and stored along the channel, as well as the various mean values of plutonium concentrations found in the region of Los Alamos. The review includes plutonium in the regional environments around Los Alamos, including the compartments of river water, active sediments, flood-plain deposits, and reservoir deposits, as well as the plutonium concentrations in the sediments of Los Alamos Canyon. Most of the plutonium in atmospheric fallout is from the testing of nuclear weapons. Five nations have detonated a total of 484 nuclear devices in the atmosphere, 466 with known dates. These explosions have injected plutonium into the general atmospheric circulation, resulting in a global distribution of fallout as the material returns to the surface. There are three types of fallout: local, tropospheric, and stratospheric. Local or early fallout arrives within a day of the detonation and consists of particles 100 to 200 microns in diameter (fine sand) transported in the lower atmosphere and deposited within several hundred kilometers of the site of the explosion. Finer particles travel greater distances and disperse over greater areas. Tropospheric fallout arrives within a month of the detonation and consists of particles less than 100 microns in diameter (mostly silt size), transported in the lower atmosphere. The global atmospheric circulation transports tropospheric fallout around the world in a band about 30 degrees latitude wide, centered on the site of the explosion. Most of the tropospheric fallout delivers plutonium to the earth’s surface in precipitation, with only about 10 percent occurring as dry fall.
Sediment and Plutonium Storage Downstream from Cochiti
Authors: Graf William L.
Published: November 2020

Downstream from White Rock Canyon and the reaches discussed in Chapter 9, the Rio Grande takes on a different character because of the presence of Cochiti Dam at the lower end of the canyon. From that point downstream, the river’s present appearance and behavior reflect the influence of the dam, which was closed in 1973. Although the channel has become narrower throughout the length of the Rio Grande since the 1930s, this change is most pronounced south of Cochiti Dam. Downstream from the Los Lunas representative reach (which ends near Bernardo), the character of the Rio Grande changes radically. Immediately below Bernardo, the Rio Puerco joins the main river, bringing with it a huge load of sediment. The Rio Grande Valley becomes much wider below Bernardo, and the twentieth-century narrowing of the channel, aided by engineering works, is even more pronounced than in upstream areas, and the vegetation community is dominated by tamarisk. The final three representative reaches discussed in this chapter share the features of great valley width, extensive channel changes, and widespread impacts of engineering works. The Peña Blanca reach, a 5-km channel section, represents conditions common along 40 km of the Northern Rio Grande between Cochiti Pueblo (site of Cochiti Dam) and the confluence with the Jemez River. The river passes Peña Blanca, a settlement based on irrigated agriculture dating from the early nineteenth century. The reach is typical of the conditions in a portion of the river where the flood plain is several times the width of the channel and where the channel has been exceedingly unstable. The reach is also instructive concerning the results of levee construction (in 1953) and dam closure (in 1973). The behavior of the channel in the Pena Blanca reach between the early 1940s and about 1990 has consistently included locational instability and progressive adjustment from a broad-braided configuration to a narrow, straighter alignment. In the 1940s, the channel was wide and unstable, with numerous major and minor threads, but the gradual reduction in water yield and radical reduction in the annual flood peaks resulted in the progressive isolation and closure of secondary channels.
Marketization
Authors: Lehmann Scott
Published: November 2020

As noted toward the end of the previous chapter, the very existence of collective values or citizen interests adds to doubts that privatizing federal lands would better satisfy our desires. But it may also be argued that we are better for having such concerns and, accordingly, that privatization would not be in our interest, inasmuch as it would eliminate opportunities for developing them. Joseph Sax observes that “at a moral and ethical level, collective values can be judged just as personal preferences can be,” though he refrains from judging them. In discussing the desire to be a part of some larger enterprise, he speaks the language of social psychology, not ethics: “there is a great deal of evidence to suggest that one of our strongest urges is to identify ourselves with a source of moral or communal authority, and to subordinate our autonomy to it; that we draw strength from values external to our purely personal convictions; and that we draw values from collective solidarity.” Yet Sax clearly thinks that instead of denying this part of “human nature,” we should arrange for its constructive fulfillment. And he evidently thinks that giving people the opportunity to join with others of like mind and debate the use of public lands in a broadly democratic system does so. Mark Sagoff’s views are similar: other things equal, it's good for people to develop and pursue common ends. As something of a Kantian, he thinks of communal action as at once constrained and called for by respect for persons. The constraint is partially embodied in certain basic rights that communal action must not violate; for example, death threats made by Idaho ranchers against USFS personnel in a controversy over grazing are clearly out of bounds. But Sagoff would argue that respect for persons demands more than merely securing the person and other property of each individual. For it is in the roles they assume that individuals develop the interests and values that give them a sense of who they are, that define them as persons, that give direction and purpose to their lives.
Generalized Computational Systems
Authors: Giunti Marco
Published: November 2020

The definition of a computational system that I proposed in chapter 1 (definition 3) employs the concept of Turing computability. In this chapter, however, I will show that this concept is not absolute, but instead depends on the relational structure of the support on which Turing machines operate. Ordinary Turing machines operate on a linear tape divided into a countably infinite number of adjacent squares. But one can also think of Turing machines that operate on different supports. For example, we can let a Turing machine work on an infinite checkerboard or, more generally, on some n-dimensional infinite array. I call an arbitrary support on which a Turing machine can operate a pattern field. Depending on the pattern field F we choose, we in fact obtain different concepts of computability. At the end of this chapter (section 6), I will thus propose a new definition of a computational system (a computational system on pattern field F) that takes into account the relativity of the concept of Turing computability. If F is a doubly infinite tape, however, computational systems on F reduce to computational systems. Turing (1965) presented his machines as an idealization of a human being that transforms symbols by means of a specified set of rules. Turing based his analysis on four hypotheses: 1. The capacity to recognize, transform, and memorize symbols and rules is finite. It thus follows that any transformation of a complex symbol must always be reduced to a series of simpler transformations. These operations on elementary symbols are of three types: recognizing a symbol, replacing a symbol, and shifting the attention to a symbol that is contiguous to the symbol which has been considered earlier. 2. The series of elementary operations that are in fact executed is determined by three factors: first, the subject’s mental state at a given time; second, the symbol which the subject considers at that time; third, a rule chosen from a finite number of alternatives.