bluuebunny/crossref_metadata_2025 huggingface dataset:
Transformation and Verification
Authors: Ashcroft E. A. , Faustini A. A. , Jaggannathan R. , Wadge W. W.
Published: November 2020

The ability to verify and reason about programs was one of the main goals behind the design and development of Lucid. In fact, from its very inception Lucid was intended to be not just a programming language, but also a formal system in which program specifications and correctness proofs could be expressed as well. Our goal was a formal programming system in which programs for “realistically” complicated problems could be proved correct with only a realistic amount of effort. The nonprocedural nature of Lucid and its mathematical semantics led naturally to a reasoning technique where properties proved of variables and functions (assertions) are true throughout the where clauses in which the variables and functions are defined, and are not just thought of as being true at particular points where they are “attached” (as would be the case in the usual verification technique for procedural programs). In that respect, Lucid verification is like verification of functional programs. The assertions proved for Lucid, however, have the basic simplicity of the assertions proved in the procedural case, and the proofs are very similar. We will illustrate the differences by using a very simple program for computing integer square roots. We will express it in an imperative language, in a functional language, and in Lucid and show how verification would be performed for each language using the different techniques. In all three techniques, we will use the following terminology from the procedural approach, namely that the precondition is a restriction on the inputs of a program and the postcondition is a desired property of the outputs of the program, assuming that the inputs satisfied the precondition.
Fluid Statics and Buoyancy
Authors: Furbish David Jon
Published: November 2020

Fluid statics concerns the behavior of fluids that possess no linear acceleration within a global (Earth) coordinate system. This includes fluids at rest as well as fluids possessing steady motion such that no net forces exist. Such motions may include steady linear motion within the global coordinate system as well as rotation with constant angular velocity about a fixed vertical axis. In this latter case, centrifugal forces must be balanced by centripetal forces (which arise, for example, from a pressure gradient acting toward the axis of rotation). Moreover, we assert that no relative motion between adjacent fluid elements exists. Fluid motion, if present, is therefore like that of a rigid body. In addition, we neglect molecular motions that lead to mass transport by diffusion. Thus, the idea of a static fluid is a macroscopic one. The developments in this chapter clarify how pressure varies with coordinate position in a static fluid. Both compressible and incompressible fluids are treated. In the simplest case in which the density of a fluid is constant, we will see that pressure varies linearly with vertical position in the fluid according to the hydrostatic equation. In addition, we will consider the possibility that fluid density is not constant. Then, variations in density must be taken into account when computing the pressure at a given position in a fluid column; the pressure arising from the weight of the overlying fluid no longer varies linearly with depth. In the case of an isothermal fluid, whose temperature is constant throughout, any variation in density must arise purely from the compressible behavior of the fluid in response to variations in pressure. In the case where temperature varies with position, fluid density may vary with both pressure and temperature. We will in this regard consider the case of a thermally stratified fluid whose temperature varies only with the vertical coordinate direction. Because fluid statics requires treating how fluid temperature, pressure, and density are related, the developments below make use of thermodynamical principles developed in Chapter 4.
Turbulent Boundary-Layer Shear Flows
Authors: Furbish David Jon
Published: November 2020

Turbulent shear flows next to solid boundaries are one of the most important types of flow in geology. In such flows, turbulence is generated primarily by boundary effects; vorticity originates near a boundary in association with the velocity gradients that arise from the no-slip condition at the boundary. Such gradients provide a ready source of vorticity for eddies and eddy-like structures to develop in response to the destabilizing effects of inertial forces, and then move outward into the adjacent flow. Eddies are also generated within the wakes of bumps that comprise boundary roughness, for example, sediment particles on the bed of a stream channel (Example Problem 11.4.2). As we have seen in Chapter 14, the fluctuating motions of turbulence involve, over any elementary area, fluxes of fluid momentum that are manifest as apparent (Reynolds) stresses. In addition, the complex motions of eddies and eddy-like structures efficiently advect heat and solutes from one place to another within a turbulent flow, and thereby facilitate mixing of heat and solutes throughout the fluid. For similar reasons, turbulent motions are responsible for lofting fine sediment into the fluid column of a stream channel and in the atmosphere. We will concentrate in this chapter on steady unidirectional flows where the mean streamwise velocity varies only in the coordinate direction normal to a boundary and the mean velocity normal to the boundary is zero. We also will adopt a classic treatment of turbulent boundary flow in developing the idea of L. Prandtl’s mixing-length hypothesis, from which we will obtain the logarithmic velocity law, a function that describes how the mean streamwise velocity varies in the coordinate direction normal to a boundary. In developing Prandtl’s hypothesis, we will see that the presence of apparent stresses associated with fluctuating motions leads to the idea of an eddy viscosity or apparent viscosity. Unlike the Newtonian viscosity, the eddy viscosity is a function of the mean velocity, and therefore coordinate position. This means that the eddy viscosity cannot, in general, be removed from stress terms involving spatial derivatives, as we previously did with the Newtonian viscosity in simplifying the Navier–Stokes equations.
Default Status: Making Sense of the World
Authors: Hardin Garrett
Published: November 2020

"There are three kinds of lies," said Benjamin Disraeli, Queen Victoria's favorite prime minister: "lies, damned lies and statistics." Scientists are inclined to argue with this, holding that statistics (properly used) are one of the glories of the scientific method. But since statistics are often not properly used it must be admitted that Disraeli had a point. As used, statistics are often a sort of black magic, accompanied by a disparagement of common sense. That won't do. As the logician Willard Van Orman Quine has said: "Science itself is a continuation of common sense. The scientist is indistinguishable from the common man in his sense of evidence, except that the scientist is more careful.” The physicist John Platt agrees in minimizing the distance between science and common sense: "It may surprise many people to know that the chain of new scientific reasoning in a whole research study is frequently less complex than an everyday business decision or a crossword puzzle or a game of chess. It would have a salutary effect on our attitudes if for twenty-four hours we could cross out the words 'science' and 'scientist' wherever they appear and put in their place the words 'man reasoning.'" Stereotypes of scientists often imply that being scientific means having a perpetually open mind. Not so. A claim that lies too far outside the accepted view of things is often completely ignored by the scientific community. For instance, half a century ago the writer of a letter to the British journal Nature claimed that the average gestation period of different animals, from rabbits to cows, was an integral multiple of the number pi (3.14159 . . .). The evidence was ample, the statistical agreement was good. But, to this day, the scientific community has ignored this claim. No understandable reason was proposed for the association of the two phenomena, and no one has been able to imagine any. It is just too ridiculous. Evidently the scientific mind is not completely open. To what extent is it closed, and how is this partial closure justified? Since population inquiries are beset by statistics, we need to understand the accepted limits of scientific inquiry.
Exponential Growth of Populations
Authors: Hardin Garrett
Published: November 2020

Historians took a long time to appreciate the importance of biological factors in human history. As the French naturalist Jean Henri Fabre (1823-1915) said: "History celebrates the battlefields whereon we meet our death, but scorns to speak of the plowed fields whereby we thrive. It knows the names of the King's bastards, but cannot tell us the origin of wheat." No doubt Fabre's criticism helped in turning the tide against the old-fashioned sort of history. History books now being written are more inclusive, more interesting. Some of them even mention population. A century before Fabre was born, even the fact of population growth was denied by some otherwise well-informed scholars. In 1721 the Baron de Montesquieu asked, in all sincerity, "How does it happen that the world is so thinly peopled in comparison with what it once was?"1 Until the nineteenth century the taking of censuses was a sporadic activity; most of the world, most of the time, lived uncensused. Primitive travel and slow communication made the counting of population over large areas difficult—and perhaps pointless. Without censuses or sampling, general impressions had to serve. When speaking of "the world" as "it once was," the baron, an educated European, no doubt had in mind the last days of the Roman Empire. There is much uncertainty about the size of world population in the olden days, but the following estimates are probably not far off.2 Over a period of about thirteen hundred years, ending in Montesquieu's time, the population of the world increased from some 190 million to about 610 million. This was more than a threefold increase, but an intelligent European could easily be unaware of both the direction and the extent of the change—for several reasons. To begin with, most of the increase in population took place outside Europe. Despite reports like Marco Polo's, to European eyes Europe was the world. Viewing the sparsely inhabited ruins of Rome, eighteenth-century Europeans deduced a decrease in world population. Awareness of long-term growth was made more difficult by erratic (but normal) fluctuations in populations. It was quite common for a region to lose a percent or two of its population during a single year because of disease.
The Demostat
Authors: Hardin Garrett
Published: November 2020

If the Old Testament preacher Koheleth could justly complain that "of the making of many books there is no end," then how much more reason do we have to complain now, some twenty-two centuries later! There are times when we fear that the snowballing "information overload" may be the downfall of civilization. Fortunately there is a counterforce to information overload: theory construction. A good theory compacts a vast body of facts into a few words or equations. For example, before Gregor Mendel published his theory of heredity, some 8,000 pages of scholarly discussion had been produced on the subject. All these documents became useless upon the publication of Mendel's forty-page paper. Today, more than a century later, we can condense Mendel's findings into a single page. The literature on human population growth is enormous. Blessedly, most of it can be safely ignored. A handful of principles enable us to incorporate the meaning of a great mass of data in a few images. The most important of these derive from "control theory," a development of the middle of the twentieth century. A careful reading of Malthus's Essay shows that control theory is implicit in his exposition. In 1948 the mathematician Norbert Weiner published Cybernetics: or, Control and Communication in the Animal and the Machine. This book briefly summarized and greatly extended a diffuse literature on the subject, introducing language that made it possible to talk more effectively about change and resistance to change. Wiener, the son of a classics scholar, derived the name of the science from a Greek word for "governor." Cybernetics deals with the logic of the mechanisms that govern the equilibrating functions of complex machines and animals. The thermostat is a convenient example. In A of Figure 11 -1 we see the graph of the temperature of a thermostated room: an irregular line fluctuating about the set point, the temperature reading at which someone has set the thermostat. As usual, time is oriented on the horizontal axis. Part B displays a collapsed time diagram of the same data: both possible excursions away from the set point are shown as alternate possibilities of the same moment in time. The "closed" nature of the resulting figure symbolizes the restriction of temperature within limits when a thermostat is in control.
The Double C-Double P Game
Authors: Hardin Garrett
Published: November 2020

"Words are wise men's counters—they do but reckon by them; but they are the money of fools." So said Thomas Hobbes in the seventeenth century. Oft-repeated words, ambiguous in meaning, can easily counterfeit for the money of the mind. Free enterprise, laissez-faire, and capitalism are examples. Walter Lippmann, an esteemed commentator in the period between the two world wars, remarked on a gap between rhetoric and behavior:… Most men have shown in their behavior that they wished to impose free capitalism on others and to escape it themselves. Employers have believed in it for their employees, and have appealed to it against factory laws and unionism. But they have not hesitated to call upon the state for protection against foreign competition. . . . There is no reason to think that business men under capitalism have had any consistent conviction of laissez-faire. Their employees have certainly not had it. They have voted for tariffs when they were told their jobs depended upon them. They have voted to close the labor market by restricting immigration. They have voted for labor laws and they have organized unions. Like their employers they have believed in laissez-faire for others…. Most men believe in laissez-faire for others, while seeking to escape it themselves. A half-century after Lippmann, the economist Milton Friedman repeated the criticism: "With some notable exceptions, businessmen favor free enterprise in general but are opposed to it when it comes to themselves." This inconsistency violates the fundamental assumption of ethical theory that moral principles must be symmetrical—sauce for the goose is sauce for the gander. But it is the very nature of egoism to want sauce for the goose only: the morality Ego lives by, if he can get away with it, is asymmetrical. The discovery that social arrangements are often asymmetrical can easily lead to cynicism. One of the myths supporting free enterprise is Emerson's story of the man who built a better mouse trap and thereby became rich as the world "beat a path to his door, though he lived in the depths of the woods." In truth, however, success more often comes by another route: an ingenious man fashions a bifurcation in the accounting system that channels the costs of his enterprise to society, while directing the profits to himself.
Isolation and Identification of Cellular Phospholipids
Authors: Hanahan Donald J.
Published: November 2020

In this chapter, some of the types of methodologies currently in use for isolation and analysis of cellular phospholipids will be outlined. Such techniques can be readily applied to experiments designed to explore the involvement of phospholipids in cellular events, such as stimulus-induced activation. Primary attention will be paid to the human platelet. If you need to justify the choice of human platelets as the cell of choice, a number of highly creditable reasons can be cited. Only three need to be considered at this point. First, the circulating platelet is of paramount importance in hemostasis, and there is convincing evidence that its membrane phospholipids are intimately involved in this process. Second, these cells can serve as excellent targets or model systems for stimulus-induced activation in which the membrane phospholipids play an important role. Third, human platelets can be isolated from whole blood by a simple, convenient centrifugal approach. Human donors are available at a very reasonable cost, and the platelets obtained from a varied spectrum of donors show remarkable consistency. Thus, one can undertake their isolation using the following method and have them available for immediate experimentation. Nonfasting venous blood is drawn (with informed consent) from male or female subjects between the ages of 20 and 40 years, who are considered to be normal and healthy and had not ingested platelet-active medication for at least 10 days prior. Blood is obtained by insertion of a butterfly infusion set (12-in. tubing from Abbott Hospitals, Inc., North Chicago, IL) with a 1-in. x 19-gauge needle into the antecubital vein. A few milliliters of blood is allowed to flow before a 60-ml plastic syringe containing 7.5 ml of an ACD [10.8% citric acid, 2.2% trisodium citrate, and 2% dextrose (w/v)] solution was attached. Four syringes were filled to the 50-ml mark and inverted gently, and the contents were transferred carefully into 50-ml plastic tubes that are then capped. The blood-to-ACD volume ratio is 6:1 (v/v). The tubes are centrifuged at 2000 rpm (830g) in a Sorvall RT 6000 centrifuge at 24°C for 15 min.
Overview and Some Fundamental Information
Authors: Erman Burak , Mark James E.
Published: November 2020

This chapter is a brief overview of the topics treated in the book. It is aimed, in particular, at providing some qualitative information on rubber elasticity theories and their relationships to experimental studies, and at putting this material into context. The following chapter describes in detail the classical theories of rubber elasticity, that is, the phantom and affine network theories. The network chains in the phantom model are assumed not to experience the effects of the surrounding chains and entanglements, and thus to move as “phantoms.” Although this seems to be a very severe approximation, many experimental results are not in startling disagreement with theories based on this highly idealized assumption. These theories associate the total Helmholtz free energy of a deformed network with the sum of the free energies of the individual chains—an important assumption adopted throughout the book. They treat the single chain in its maximum simplicity, as a Gaussian chain, which is a type of “structureless” chain (where the only chemical constitution specified is the number of bonds in the network chain). In this respect, the classical theories focus on ideal networks and, in fact, are also referred to as “kinetic” theories because of their resemblance to ideal gas theories. Chain flexibility and mobility are the essential features of these models, according to which the network chains can experience all possible conformations or spatial arrangements subject to the network’s connectivity. One of the predictions of the classical theories is that the elastic modulus of the network is independent of strain. This results from the assumption that only the entropy at the chain level contributes to the Helmholtz free energy. Experimental evidence, on the other hand, indicates that the modulus decreases significantly with increasing tension or compression, implicating interchain interactions, such as entanglements of some type or other. This has led to the more modern theories of rubber elasticity, such as the constrained-junction or the slip-link theories, which go beyond the single-chain length scale and introduce additional entropy to the Helmholtz free energy at the subchain level.
Bioelastomers
Authors: Erman Burak , Mark James E.
Published: November 2020

There are a variety of biopolymeric materials which exhibit rubberlike elasticity. This is perhaps to be expected when one recalls that most biopolymers are randomly coiled chains with considerable flexibility, and that they are frequently covalently cross-linked or have sufficient numbers of aggregated units to exist in network structures. One very large group of plant materials, the polysaccharides, are in this category, and they do require some elastomeric properties in their functioning. In many of these cases, however, the cross-linking is there primarily for a secondary purpose, such as preventing solubility. When swollen with water or aqueous solutions, such polysaccharides form gels which do exhibit the high deformability and recoverability that are the hallmarks of rubberlike elasticity. Not surprisingly, however, relatively few mechanical property measurements have been carried out to characterize the structures of these gels. The bioelastomers occurring in animals, including vertebrates and mammals, however, are there specifically for their rubberlike elasticity. They are vital, for example, for the functioning of skin, arteries and veins, and much of the lung and heart tissue. Since they are produced by the ribosome “factories” in the body, they are proteins. Thus, the major focus of this chapter is on those proteins specifically designed to function as bioelastomers. It is useful to summarize some general information on bioelastomers that is presented elsewhere. Even with the temporary restriction to bioelastomers which are proteins, there is an almost staggering variety of interesting materials. For example, there is elastin in vertebrates (including mammals) resilin in insects abductin in mollusks, arterial elastomer in octopuses, circulatory and locomotional proteins in cephalopods, and viscid silk in spider webs. Since they are mammals, polymer scientists and engineers who are interested in bioelastomers have focused heavily on elastin! Any materials of this type, however, are worth studying in their own right, to learn more about rubberlike elasticity and biological function. Such studies should also provide guidance on how Nature might be mimicked by synthetic chemists, to produce better nonbiological elastomers.
History, Geology, Engineering, and Archaeology
Authors: Crouch Dora P.
Published: November 2020

For convenience, human knowledge, especially in the German and American educational systems, has been separated into disciplinary packages. Thus chemistry, for instance, is defined by certain analytical actions taken toward certain materials, to answer a particular group of questions. Unfortunately, many topics are not amenable to isolating methodology. Cities, for instance, are so complex that understanding them requires coordinated research by historians of many specialties, by architects and planners, by sociologists and psychologists, and by statisticians and geographers, all of whom also benefit from the insights of scientific disciplines. Planet Earth is even more complicated and calls for every field of expertise to examine it and to synthesize results. Four disciplines that contribute to this study are history, geology, engineering, and archaeology. History may be the most recalcitrant of the humanist disciplines, notorious for partial or complete gaps in understanding and fated to reinvestigate earlier situations and earlier research. History reconstructs contexts in which past reality can be comprehended. Although human knowledge is so variable that no scientific law can sum it up (Wright 1975), we can tell stories that reveal our insights. For every attempt at general history and geography such as that of Herodotus, there are dozens or hundreds of more or less philosophical and dramatic memoirs such as those of Julius Caesar. Sometimes the only surviving data is from dynastic chronologies, for example, I and II Samuel in the Bible. Little of this ancient history involved “research” as we now understand the process (Gabba 1981). Ancient history is still monopolized by philologists, whose first passion is language and who are often out of phase with important methodological developments in history (Ramsey 1890, Ch. 3, History in Classics). Like their ancient predecessors who concentrated on the elite, modern historians of Greco-Roman times may fail to investigate ordinary people. Modern cities are places where people dance, use computers, sing, bathe, and vote. Realization of our diversity of behavior impels us to expand the study of ancient cities to incorporate their similar diversity.
Convection For Northward Interplanetary Field
Authors: Kennel Charles F.
Published: November 2020

Besides common sense, a number of results suggest that we can learn more about the slow “viscous” flow state by studying the magnetosphere during northward interplanetary field conditions. In particular, statistical studies have consistently identified a “residual” state of magnetospheric and ionospheric convection in northward field conditions. The integrated potential across the high latitudeionosphere does not drop below a certain resting value of about 20 kV even when the interplanetary field has been due north for several hours. There appears to be a similar residual component of geomagnetic activity that is independent of the direction of the interplanetary field (Scurry and Russell, 1991). Its correlation with the dynamic pressure of the solar wind strengthens our suspicion that it is related to viscosity. Will we be able to prove the convection in this residual state is driven by viscosity? Does the flow in northward field conditions resemble the underlying irregular flow state of the plasma sheet found at other times? Does the magnetosphere approach the teardrop configuration during prolonged intervals of northward interplanetary field? These are but a few of the questions that whet our interest in convection during northward field conditions. One does not arrive at the state of pure viscous convection immediately after the interplanetary field swings northward. Dungey (1963) was the first of many to argue that a northward magnetosheath field line will reconnect with an open tail lobe field line to create one that is connected to the ionosphere at one end and draped over the dayside magnetopause at the other. The sudden reconfiguration of stress will lead to sunward convection on the newly reconnected field lines. In the ionosphere, this superposes a “reverse” two-cell convection pattern in the central polar cap upon the two “direct” convection cells. If and when the draped reconnected field line finds a partner in the opposite tail lobe with which to reconnect, a newly closed field line will form. Dungey had imagined that the same magnetosheath field line would reconnect simultaneously with both tail lobes, in which case the rate at which open magnetic flux is closed depends upon the rate of tail-lobe reconnection.
The Auroral Substorm
Authors: Kennel Charles F.
Published: November 2020

Around the time the steady convection model was being developed, Akasofu (1964) was arranging ground-based magnetometer and all-sky camera observations of the complex time dependence of nightside auroral activity into the central phenomenological conception of tune-dependent magnetospheric physics—the auroral substorm. In this chapter, we assemble a description of a substorm from modern observations. We will see that observations of electric fields, auroral X rays, cosmic noise absorption, ionospheric density, and geomagnetic micropulsations have also been successfully ordered by the substorm paradigm. At the same time, it will become clear that each individual substorm has its own irreducible individuality, and that our summary description is really a list of effects that anyone thinking about substorms ought to consider. No real substorm will look exactly like the one described here. Spacecraft observations of auroral light, precipitation, currents, and fields from polar orbit have held out high promise for unified understanding of the development of the auroral substorm around the entire oval. Without truly global auroral observations, it would be difficult to establish decisive contact with observations of large-scale convection and the associated changes in magnetospheric configuration. Despite the high promise and the many other successes of spacecraft observations of the aurora, synthetic understanding of the time development of the auroral substorm at all local times, dayside and nightside, evening and dawn, has been slow in emerging, perhaps because a stringent combination of field of view, sensitivity, space and time resolution, and multispectral capability is required. One needs images of the whole oval with sufficient space resolution to identify important arc structures (50-100 km or better) in a temporal sequence that can articulate the evolution of activity on better than the 10-minute time scale on which polar cap convection develops. Only recently has it been possible to observe auroral activity at all local tunes around the auroral oval simultaneously and follow its time development from the beginning of the growth phase until well into the expansion phase. This amplification of the original paradigm is the subject of Sections 12.2 and 12.3.
The Geosynchronous Substorm
Authors: Kennel Charles F.
Published: November 2020

The reconnection model of substorms deals with the large-scale changes in the structure of the magnetosphere and tail as convection intensifies following a sudden increase in the dayside reconnection rate. The model has difficulty making statements relevant to the small scales that characterize auroral onset. However, there has been considerable progress in assembling high-resolution observations of the events in space that now appear to be tightly coupled to the dramatic auroral events that first defined the term substorm. We will call this clear and consistent ensemble the geosynchronous model of substorms, since most of it was first conceived from observations made on geostationary spacecraft. We will also include in this ensemble the recent observations made using the quasigeostationary spacecraft, AMPTE/CCE, and so, by the geosynchronous substorm, we really mean the substorm as it appears on the earth's nightside typically between 6 and, say, 10 RE downtail. The earth’s magnetic field at geosynchronous orbit is about 100 nT, some three times larger than in the tail lobes. Study of quiet field intervals singles out the dependence of the geosynchronous field on solar wind dynamic pressure, since the modulation due to changes in the direction of the interplanetary field is presumably negligible during quiet conditions. The periodic variations in the quiet field depend on local time, season, and orientation of the earth’s dipole axis relative to spacecraft location (McPherron and Barfield, 1980; Rufenach et al., 1992). Superposed on the quiet field are perturbations up to about 50 nT due to several magnetospheric current systems, including the magnetopause current, the ring current, and the cross-tail current; the most striking are due to changes in the cross-tail current system. Observations from geosynchronous orbit were the first to indicate that the nightside magnetic field becomes more “tail-like” during substorm growth phase, and more dipolar during the expansion phase. This simple observation is the foundation on which today’s elaborate geosynchronous substorm model rests. The geosynchronous field becomes progressively more “tail-like” as the cross-tail current system intensifies and/or moves earthward during the substorm growth phase (McPherron et al., 1975; Coleman and McPherron, 1976; McPherron, 1979; Kauffmann, 1987).
The Role of GIS in the Management of Archaeological Data: An Example of Application for the Spanish Administration
Authors: Bosqued Concepción Blasco , Espiago Javier
Published: November 2020

The idea of collecting all archaeological findings and sites of a particular region is at least as old as the first archaeological studies and perhaps prior to the scientific development of the discipline of archaeology itself. However, the first archaeological maps (cartas arqueológicas) had very far different objectives than those of today. The first example of this sort dates from 1818. In Spain, the Law of Archaeological Excavations promotes the elaboration of an exhaustive inventory since 1941, when the first archaeological map of the province of Soria, compiled by Mr. Blas Taracena, appeared, and in 1945, M. Almagro Basch, together with José Colominas and José Serra Ráfols, led the effort to compile the archaeological map of the province of Barcelona and four other provinces. These six archaeological maps of provinces followed the criteria adopted by other European countries like Italy, Switzerland, and Yugoslavia. In each map, the names of all counties were organized alphabetically; within counties, the names of sites and other archaeological findings, either industrial or artistic sites, appeared in chronological order from the Paleolithic to the end of the Hispanic-Visigothic period (eighth century). The scales of these maps varied from 1:50,000 to 1:400,000. Changes produced by the new political map of Spain during the 1980s, together with the transfer of responsibilities, transformed the “official” archaeological maps into archaeological maps for each “autonomic” government of the different provinces. These inventories had a fundamental goal: an exhaustive knowledge of the patrimony for its preservation and its study. They include a profound and methodical process and contain not only all existing literature, but also a complete survey of the field to locate whatever possible, including medieval, modern or contemporary testimonies. The volume of data is so great that a computerized system is necessary, both for the creation of a database and for the need to have a precise cartography that helps to preserve archaeological remains. At the moment, the autonomic governments initiated are in the stage of data collection for these comprehensive maps. In any case, besides these “official” series, other works covering smaller regions exist.
Diffusion in Biological Systems
Authors: Saltzman W. Mark
Published: November 2020

Drug diffusion is an essential mechanism for drug dispersion throughout biological systems. Diffusion is fundamental to the migration of agents in the body and, as we will see in Chapter 9, diffusion can be used as a reliable mechanism for drug delivery. The rate of diffusion (i.e., the diffusion coefficient) depends on the architecture of the diffusing molecule. In the previous chapter a hypothetical solute with a diffusion coefficient of 10-7 cm2/s was used to describe the kinetics of diffusional spread throughout a region. Therapeutic agents have a multitude of sizes and shapes and, hence, diffusion coefficients vary in ways that are not easily predictable. Variability in the properties of agents is not the only difficulty in predicting rates of diffusion. Biological tissues present diverse resistances to molecular diffusion. Resistance to diffusion also depends on architecture: tissue composition, structure, and homogeneity are important variables. This chapter explores the variation in diffusion coefficient for molecules of different size and structure in physiological environments. The first section reviews some of the most important methods used to measure diffusion coefficients, while subsequent sections describe experimental measurements in media of increasing complexity: water, membranes, cells, and tissues. Diffusion coefficients are usually measured by observing changes in solute concentration with time and/or position. In most situations, concentration changes are monitored in laboratory systems of simple geometry; equally simple models (such as the ones developed in Chapter 3) can then be used to determine the diffusion coefficient. However, in biological systems, diffusion almost always occurs in concert with other phenomena that also influence solute concentration, such as bulk motion of fluid or chemical reaction. Therefore, experimental conditions that isolate diffusion—by eliminating or reducing fluid flows, chemical reactions, or metabolism—are often employed. Certain agents are eliminated from a tissue so slowly that the rate of elimination is negligible compared to the rate of dispersion. These molecules can be used as “tracers” to probe mechanisms of dispersion in the tissue, provided that elimination is negligible during the period of measurement. Frequently used tracers include sucrose [1, 2], iodoantipyrene [3], inulin [1], and size-fractionated dextran [3, 4].
Limits to Parallel Computation
Authors: Greenlaw Raymond , Hoover H. James , Ruzzo Walter L.
Published: November 2020

This book provides a comprehensive analysis of the most important topics in parallel computation. It is written so that it may be used as a self-study guide to the field, and researchers in parallel computing will find it a useful reference for many years to come. The first half of the book consists of an introduction to many fundamental issues in parallel computing. The second half provides lists of P-complete- and open problems. These lists will have lasting value to researchers in both industry and academia. The lists of problems, with their corresponding remarks, the thorough index, and the hundreds of references add to the exceptional value of this resource. While the exciting field of parallel computation continues to expand rapidly, this book serves as a guide to research done through 1994 and also describes the fundamental concepts that new workers will need to know in coming years. It is intended for anyone interested in parallel computing, including senior level undergraduate students, graduate students, faculty, and people in industry. As an essential reference, the book will be needed in all academic libraries.
P-Complete Algorithms
Authors: Greenlaw Raymond , Hoover H. James , Ruzzo Walter L.
Published: November 2020

Our focus up to this point has been primarily on problems — either decision, search, or function. In this chapter we shift directions and apply P-completeness theory to the study of algorithms. The theory when extended properly will allow us to make statements about whether or not certain sequential algorithms will parallelize well. The phrase "inherently sequential algorithm" is one that appears frequently in the research literature. The general intent of the phrase is obvious. However, if pressed for details one might come up with several different possible formal meanings. In this chapter we describe one approach that gives the phrase a precise interpretation. The work on P-complete algorithms began with Anderson [12] and was continued by Greenlaw [133, 135]. Much of the discussion contained in this chapter is taken from these references. That a problem is P-complete is evidence it is unlikely to have small space sequential solutions, or unlikely to have fast parallel solutions using a polynomial amount of hardware. Of course, being P-complete also means that the problem does have a polynomial time algorithm. For many P-complete decision problems, this algorithm appears explicitly or implicitly in the statement of the problem. For example, asking whether a vertex is in the lexicographically first maximal clique is essentially asking whether the vertex is in the maximal clique found by the obvious greedy algorithm — the same greedy algorithm that shows the problem is in P. This specification of a particular polynomial time algorithm in addition to the nonalgorithmic properties desired of a solution occurs in most of the search problems in Section A.3, many of the problems of a greedy or lexicographically first nature, and numerous graph problems in Section A.2. These P-completeness results say more about the difficulty of parallelizing the associated sequential algorithm than they do about the intrinsic difficulty of the decision problem. In many cases the particular sequential algorithm does not seem to adapt well to parallelism. Yet it may be the case that a modified version of the problem that avoids mentioning a sequential algorithm does have a highly parallel solution.
Weights Of Evidence Modeling And Weighted Logistic Regression For Mineral Potential Mapping
Authors: Agterberg F.P. , Bonharn-Carter G.F.
Published: November 2020

During the past few years, we have developed a method of weights of evidence modeling for mineral potential mapping (cf. Agterberg, 1989; Bonham- Carter et al., 1990). In this paper, weights of evidence modeling and logistic regression are applied to occurrences of hydrothermal vents on the ocean floor, East Pacific Rise near 21° N. For comparison, logistic regression is also applied to occurrences of gold deposits in Meguma Terrane, Nova Scotia. The volcanic, tectonic, and hydrothermal processes along the central axis of the East Pacific Rise at 21° N were originally studied by Ballard et al. (1981). Their maps were previously taken as the starting point for a pilot project on estimation of the probability of occurrence of polymetallic massive sulfide deposits on the ocean floor (Agterberg and Franklin, 1987). In the earlier work, presence or absence of deposits in relatively large square cells was related to explanatory variables quantified for small square cells (pixels) by means of stepwise multiple regression and logistic regression. In this paper, weights of evidence modeling and weighted logistic regression are applied to the same maps but a geographic information system (Intera- TYDAC SPANS, 1991) was used to create polygons for combinations of maps. These polygons can be classified taking the different classes from each map. Probabilities estimated for the resulting "unique conditions" can be classified and displayed. The vents are correlated with only a few patterns and it is relatively easy to interpret the weights and final probability maps in terms of the underlying volcanic, tectonic, and hydrothermal processes. The vents are situated along the central axis of the rise together with the youngest volcanics. They occur at approximately the same depth below sea level, tend to be associated with pillow flows rather than sheet flows, and with absence of fissures which are more prominent in older volcanics. Contrary to weights of evidence modeling, weighted logistic regression (cf. Agterberg, 1992, for discussion of algorithm) can be applied when the explanatory variables are not conditionally independent. This method was previously applied by Reddy et al. (1991) to volcanogenic massive sulfide deposits in the Snow Lake area of Manitoba.
Executable statements
Authors: Schenck Douglas , Wilson Peter
Published: November 2020

Executable statements define the actions of functions, procedures and rules. They define the logic and actions needed to support the definition of constraints by acting on parameters, local variables and constants. The shortest possible ‘executable’ statement is just a semicolon. It is called a null statement because it does nothing. Such a statement is not useless, however, as you can use a null statement to stake out territory for future use, or perhaps to make the absence of a statement stand out more clearly as in the example following. …IF a = 13 THEN ; -- do nothing ELSE b := 5 ; -- otherwise give b a value END_IF ;... The Alias statement gives a short name (alias) to an identifier that might be long or clumsy to write. The alias exists only in the scope of the alias statement and references to the alias is the same as writing out the identifier out in full. The assignment statement is used to give a value to a local variable or parameter. The type of the expression assigned to the variable must be compatible with the variable or parameter. Some assignments are shown below. The target variable and the expression being assigned to it are assignment compatible if any of the following hold true: • The types are the same. • The expression results in a type which is a subtype of the type declared for the variable being assigned to. • The type of the variable being assigned to is a select type and the expression results in a type which is a member of that select type. The Case statement executes one (or perhaps zero) statement based on the value of an expression. The statement executed is chosen depending on the value of the Selector. The case statement consists of an expression, which is the case selector and a list of alternative actions, each one preceded by a case label. Agreement between the type of the case label and the case selector is required. The first occurring statement having a case label that evaluates to the same value of the case selector is executed.
Theoretical considerations of electron-transfer reactions
Authors: Schmickler Wolfgang
Published: November 2020

Chemical and electrochemical reactions in condensed phases are generally quite complex processes; only outer-sphere electron-transfer reactions are sufficiently simple that we have reached a fair understanding of them in terms of microscopic concepts. In this chapter we give a simple derivation of a semiclassical theory of outer-sphere electron-transfer reactions, which was first systematically developed by Marcus and Hush in a series of papers. A more advanced treatment will be presented in Chapter 19. We begin with qualitative considerations. During the course of an outer-sphere electron-transfer reaction, the reactants get very close, up to a few Ångstroms, to the electrode surface. Electrons can tunnel over such a short distance, and the reaction would be very fast if nothing happened but the transfer of an electron. In fact, outer-sphere reactions are fast, but they have a measurable rate, and an energy of activation of typically 0.2 - 0.4 eV, since electron transfer is accompanied by reorganization processes of atoms and molecules that require thermal activation. While the reacting complex often has the same or similar structure in the oxidized and reduced form, metal-ligand bonds are typically shorter in the complex with the higher charge, which is also more strongly solvated. So the reaction is accompanied by a reorganization of both the complex, or inner sphere, and the solvation sheath, or outer sphere (see Fig. 6.1). These processes require an energy of activation and slow the reaction down. A natural question is: In which temporal order do the reorganization processes and the proper electron transfer take place? The answer is given by the Frank-Condon principle, which in this context, states: First the heavy particles of the inner and outer sphere must assume a suitable intermediate configuration, then the electron is exchanged isoenergetically, and finally the system relaxes to its new equilibrium configuration. A simple illustration is given in Fig. 6.2, where we have drawn potential energy surfaces for the reduced and the oxidized state as a function of two generalized reaction coordinates representing the positions of particles in the inner and outer sphere.