bluuebunny/crossref_metadata_2025 huggingface dataset:
Chorismate Mutase, Essentially a Template Enzyme
Authors: Lipscomb W.N. , Chook Y.M.
Published: November 2020

It was a particular pleasure for the senior author to open the scientific sessions which celebrated Oleg Jardetzky’s 65th birthday anniversary. Oleg was a student in my Physical Chemistry course at the University of Minnesota in 1950, and received an M.D, from the Medical School in 1954. At that time he came to my office to ask for a Ph.D. research problem in statistical mechanics of membrane processes, and I suggested that he study instead the NMR quadrupole line broadening of Na+ in solutions of small biologically interesting molecules as they interact with Na+. This research, with John Wertz, is surely an early study of biologically interesting problems using NMR, and I consider it a privilege to have helped to start Oleg on his outstanding career in this area of science. The enzyme chorismate mutase from Bacillus subtilis forms the topic of this chapter, and the method is single crystal X-ray diffraction. It is a very recent study and highlights some questions. Only 127 amino acids are present in the polypeptide chain, and the structure would be a candidate for NMR pulse methods, except that the molecule in the solution and in the crystal is trimeric. (We were told by the biochemists that it was dimeric!) Non-crystallographic symmetry (based on vector distances) was helpful in solving the structure, and I wonder if there is some partly equivalent use of molecular symmetry (based on scalar distances) that would simplify the analysis of the NMR spectrum of the trimer in solution. The second question is how nearly the same are the monomers in the crystallographic unit. In the crystal there are actually 12 monomers (i.e., 4 trimers)in the asymmetric unit of the crystal. When all 12 are superimposed the polypeptide chains are very similar indeed. No doubt the trimerization reduces the distortions of structure below those expected for isolated monomers. The third question relates to the chemical mechanism by which chorismate mutase isomerizes chorismate to prephrenate in a pericyclic reaction, the only pericyclic reaction that is known to be catalyzed by an enzyme.
Clinicians Need Localized Proton MRS of the Brain in the Management of HIV-Related Encephaiopathies
Authors: Cozzone P.J. , Vion-Dury J.
Published: November 2020

The neurological complications of AIDS (neuro AIDS) represent the principal cause of disability and death in HIV-patients (Gray et al., 1993; McArthur, et al., 1993). Several types of lesions affect the brain tissue: direct infection of the nervous tissue by HIV, opportunistic infections (such as toxoplasmosis, cytomegalovirus encephalitis, tuberculosis, progressive rnultifocal encephalopathy....), and lymphomas. The AIDS-related dementia complex (ADC) affects about 60% of patients in the late stage of AIDS. ADC is characterized by the occurrence of sub-cortical dementia with cognitive, behavioral, and motor decline, psychomotor slowing and apathy. ADC is related to the presence of a diffuse encephalopathy leading to a cortical and sub-cortical atrophy, as well as diffuse white-matter lesions. There is a distinct advantage in diagnosing as early as possible the neurological complications (e.g. encephalopathy) of AIDS, since early treatment can improve significantly the quality of life in patients by slowing down or even stopping the neurological and psychological degradation. Neuroimaging techniques, and mainly magnetic resonance imaging (MRI), constitute so far the best diagnostic tools of neuro-AIDS (Kent et al., 1993; Mundinger et al., 1992). In addition, localized magnetic resonance spectroscopy (MRS) of the brain provides a non-invasive exploration of intracerebral metabolism in vivo, and can be performed following a standard MRI examination [for a review see Vion-Dury et al. (1994)]. Several key molecules of brain metabolism can be detected, including N-acetyl-aspartic acid which is thought to be a neuronal marker, choline-containing molecules (involved in phospholipid metabolism), glutamate, glutamine, inositol, phosphocreatine and creatine, and lactate. Recently, significant modifications in the concentration of brain metabolites detected by phosphorus and proton MRS have been described in patients with ADC (Bottomley et al., 1992; Deicken et al., 1991; Menon et al., 1992; Chong et al., 1993; Meyerhoff et al., 1993; Confort-Gouny et al., 1993). In a preliminary study, we have observed that even, if MR images are normal (without atrophy, focal or diffuse lesions) or if the patients are neuroasymptomatic, the values of metabolic parameters measured by MRS are often modified (Vion-Dury et al., 1994).
Nuclear Magnetic Resonance Spectroscopy Studies of Cancer Cell Metabolism
Authors: Kaplan O. , Cohen J.S.
Published: November 2020

Nuclear magnetic resonance spectroscopy (NMR) is a powerful technique that provides information on biochemical status and physiological processes both in-vitro and in-vivo. The metabolism of intact cells and tissues can be studied in a continuous manner, and thus, NMR is a unique non-invasive research tool enabling detection of the metabolic changes as they occur (Cohen et al., 1983; Morris, 1988; Daly and Cohen, 1989). The first NMR study of cellular metabolism was done some 20 years ago, when Moon and Richards reported on the diphosphoglyceric acid (DPG) and pH shifts in erythrocytes (Moon, and Richards, 1973). NMR studies of metabolism of tumor cells were initiated by Navon et al. who investigated phosphorylated compounds in Ehrlich ascites cells (Navon etal., 1977). The choice of the element and isotope for a specific study of metabolism depends on its NMR properties, and the required data. The proton has the highest NMR sensitivity, and is the most abundant nucleus in biological molecules. However, this may cause difficulties in the interpretation and assignment of the 1H NMR spectrum. Moreover, since metabolic studies are usually performed in aqueous solutions, the huge signal from the water protons should be suppressed. Similarly, the wide signals arising from proteins and membrane components should be suppressed. These problems can be addressed now by several innovative NMR methods (Daniels et al., 1976; van Zijl and Cohen, 1992). The most widely used nucleus in NMR studies of metabolism has been 31p (see reviews Cohen (1988); Kaplan et al. (1992)). Phosphorous NMR spectroscopy can provide data on energy metabolism and substrate utilization, phospholipid pathways, precise intracellular pH, and membrane permeability and ion and water distribution. The spectrum is easy to interpret, but the number of compounds which are detectable is limited. Carbon NMR is also useful for NMR studies of metabolism since it is found in most biological compounds; however, 13C has a natural abundance of only 1.1%, and 13C enrichment is necessary. Other nuclei which are used less often in NMR studies of cellular metabolism are 23Na (Gupta et al., 1984), 19F (Malet-Martino, et al., 1986), and rarely 15N (Legerton et al., 1983) and 39K (Brophy et al., 1983).
Toward a New Protection Paradigm
Authors: van Schaik Carel P. , Kramer Randall A.
Published: November 2020

During the past century, the standard measure for safeguarding the maintenance of biodiversity has been the establishment of protected areas in which consumptive uses by humans are minimized. Over the years, the design of protected areas has evolved from the creation of small refuges for particular species to the protection of entire ecosystems that are large enough to maintain most if not all their component species and that are mutually interconnected wherever possible. While many other, equally important, measures are now being contemplated and implemented (e.g., comprehensive land-use planning, sustainable development), protected areas remain the cornerstone of all conservation strategies aimed at limiting the inevitable reduction of this planet’s biodiversity (e.g., World Conservation Strategy, Caring for the Earth, Global Biodiversity Strategy). Existing protected rain forest areas suffer from an array of problems that reduce their effectiveness in a broad conservation strategy. They cover a scant 5 percent of tropical rain forest habitats (WCMC, 1992)— arguably not enough to forestall species extinction, especially since the proportions of areas protected vary appreciably from region to region. Protected areas are often not sited appropriately, and they are often too small to maintain the full diversity of their communities. They will in future be affected by external forces (Neumann and Machlis, 1989), such as changes in local climates caused by extensive deforestation, pollution, or fires emanating from outside; introduced exotic species; and global climate change, which in parts of the tropics will likely manifest itself as an increase in the frequency of long droughts. Fortunately, these existing and anticipated threats are being addressed in some countries and regions by measures such as integrated land-use planning, redesigning parks, and establishing corridors, although ecologists are concerned that not enough is being done (see chapter 3). These shortcomings of protected area networks are significant and need to be redressed, but human activities currently pose far more serious threats to protected areas.
Introduction—A Bit of History
Authors: Epstein Irving R. , Pojman John A.
Published: November 2020

Oscillations of chemical origin have been present as long as life itself. Every living system contains scores, perhaps hundreds, of chemical oscillators. The systematic study of oscillating chemical reactions and of the broader field of nonlinear chemical dynamics is of considerably more recent origin, however. In this chapter, we present a brief and extremely idiosyncratic overview of some of the history of nonlinear chemical dynamics. In 1828, Fechner described an electrochemical cell that produced an oscillating current, this being the first published report of oscillations in a chemical system. Ostwald observed in 1899 that the rate of chromium dissolution in acid periodically increased and decreased. Because both systems were inhomogeneous, it was believed then, and through much of our own century, that homogeneous oscillating reactions were impossible. Degn wrote in 1972 (p. 302): “It is hard to think of any other question which already occupied chemists in the nineteenth century and still has not received a satisfactory answer.” In that same year, though, answers were coming. How it took so long for the nature of oscillating chemical reactions to be understood and how that understanding eventually came about will be the major focus of this chapter. Although oscillatory behavior can be seen in many chemical systems, we shall concentrate primarily on homogeneous, isothermal reactions in aqueous solution. In later chapters, we shall broaden our horizons a bit. While the study of oscillating reactions did not become well established until the mid-1970s, theoretical discussions go back to at least 1910. We consider here some of the early theoretical and experimental work that led up to the ideas of Prigogine on nonequilibrium thermodynamics and to the experimental and theoretical work of Belousov, Zhabotinsky, Field, Körös, and Noyes, all of whom did much to persuade chemists that chemical oscillations, traveling fronts, and other phenomena that now comprise the repertoire of nonlinear chemical dynamics were deserving of serious study. Alfred Lotka was one of the more interesting characters in the history of science. He wrote a handful of theoretical papers on chemical oscillation during the early decades of this century and authored a monograph (1925) on theoretical biology that is filled with insights that still seem fresh today.
Transport and External Field Effects
Authors: Epstein Irving R. , Pojman John A.
Published: November 2020

Thus far, we have implicitly assumed that chemical species move only by diffusion. In fact, a number of external forces can affect mass transport, with significant and interesting effects on chemical waves. In this chapter, we consider three types of fields: gravitational, electric, and magnetic. These always exist, though their magnitudes are usually very small. As we shall see, small fields can have surprisingly large effects. Gravity is a ubiquitous force that all living and chemical systems experience. People largely ignored the profound effect that living with gravity has upon us until humans spent significant time in space. Bone loss and changes to the vascular systems of astronauts (Nicogossian et al., 1994) are still not well understood. Eliminating the effects of gravity is not easy. Enormous cost and effort have been expended to simulate gravity-free conditions in drop towers, parabolic airplane flights, or in Earth orbit. A simple calculation seems to suggest that gravity should have negligible influence on chemical reactions. The mass of a molecule is on the order of 10-26 kg, which translates into a gravitational force of about 10-25 N. We can compare this with the force of attraction between the electron and the proton in a hydrogen atom, which is of the order 10-8 N. Even allowing for shielding effects, the electrostatic forces that cause chemical bonds to be made and broken will always be many orders of magnitude stronger than gravitational forces. So gravity does not affect the fundamental atomic and molecular interactions, but it can drastically alter the macroscopic transport of heat and matter through convection, or macroscopic fluid motion. Natural convection is the movement of fluid as the result of differences in density, so that denser fluid sinks and less dense fluid rises. This motion is resisted by the viscosity of the medium, which acts like friction does in slowing the motion of solids. The study of convection is an entire area of physics, and we will touch only on a few aspects. The reader is referred to some excellent texts on the subject (Tritton, 1988; Turner, 1979).
Surface Charge
Authors: Zhang X. N. , Zhao A. Z.
Published: November 2020

The surface of soil colloids carries electric charges, and these surface charges are the basic cause for soil to possess a series of surface properties. Soil surface charges affect the chemical properties of the soil through varying the quantity of electric charge and the surface charge density. For example, adsorptions of cations and anions are caused by negative and positive surface charges of the soil, respectively. The amount of ions adsorbed is determined by the quantity of surface charge, whereas the tightness of adsorption is related to charge density. In addition, the migration of ions in soil, the formation of organo-mineral complexes,and the dispersion, flocculation, swelling, and shrinkage are all affected by surface charge properties of the soil. Therefore, surface charge properties have an important bearing on soil structure and plant nutrition. Variable charge soils are characterized by the high content of iron and aluminum oxides. The clay mineralogical composition is dominated by 1:1-type minerals, such as kaolinite. These two factors make the surface charge properties of variable charge soils distinctly different from those of constant charge soils of temperate regions which chiefly containin 2:1-type clay minerals. However, unlike the case for pure variable charge minerals, in variable charge soils there is generally the presence of a certain amount of 2:1-type clay minerals. Therefore, as a mixture of variable charge minerals and constant charge minerals, the surface charge properties of variable charge soils is more complicated. In this chapter, the origin and factors affecting surface charges of the soil as well as the relationship between these charges and soil type will be discussed. Despite the complexity in composition, a soil may be regarded as a mixed system consisting of constant charge surface materials and constant potential surface materials in different ratios (Anderson and Sposito, 1992; Gillman and Uehara, 1980). Examples of the former type such as montmorillonite and vermiculite carry permanent negative charges, while those of the latter type such as iron oxide and aluminum oxide carry variable charges. Commonly found constant charge clay minerals in soils include those layer silicates such as hydrous mica, vermiculite, montmorillonite, and chlorite.
Electrokinetic Properties
Authors: Zhang H.
Published: November 2020

Cations and anions adsorbed by soil particles carrying surface charges are not present totally on the surface of the particles. Actually, in a soil-water system, a portion of adsorbed ions is distributed near the surface, forming an electric double layer at the interface between the solid particle and the liquid phase. When the two phases have a relative movement in an electrical field or are affected by other forces, the system can exhibit certain electrical properties, called electrokinetic properties. Electrokinetic properties of soils are the overall reflection of the distribution of various kinds of ions in the electric double layer of a soil-water system. They are related to both the characteristics of the soil and the nature of ions. For variable charge soils, because they adsorb anions as well as cations and during the adsorption both electrostatic force and specific force are involved, their electrokinetic properties frequently manifest themselves in a complex manner. As shall be seen in the present chapter, the electrokinetic properties of variable charge soils exhibit certain characteristics different from those of constant charge soils, and these characteristics are of significance for further distinguishing soil types among these soils. All the electrokinetic phenomena occurring in any colloid system result from the existence of the electric double layer. The same holds true for soils. Therefore, in this section the theory of the electric double layer along with its relation to various electrokinetic properties will be introduced first, and then the complexities in soil systems in this respect will be examined. When two phases are in contact, owing to the difference in properties, a redistribution of electric charge will occur at the interface between the two phases, leading to the formation of two layers with charges equal in quantity but opposite in sign between the two sides of the interface. This pair of charged layers is called electric double layer. It is a microscopically charged system present in the interfacial region between the two phases. The electric potential may vary at different positions within the system, but the system as a whole is electrically neutral.
Controversy: Backlash Against the Catholic Revival
Authors: Gleason Philip
Published: November 2020

The eruption of anti-Catholic feeling that reached its climax around 1950 is best understood as a backlash against what was regarded as undue Catholic influence in politics, public morality, and general social policy. Although it testified in a negative way to the reality of the Catholic Revival, it came as a shock to Catholics who did not think they had given just cause for complaint. Their predominant reaction was an impassioned rejection of the charges against them. At the same time, however, reasonable Catholics wished to mitigate the existing tensions by removing any grounds for legitimate criticism. Hence a more irenic and accommodationist line of thought developed, which, though based on the natural law, set in motion tendencies not fully consonant with the premises of the the Catholic Revival. To understand how these crosscurrents affected the ideological context of Catholic higher education, we turn first to the anti-Catholic backlash. Suspicion of and hostility toward the Catholic church, which had subsided after the Al Smith campaign of 1928, began to reawaken in the mid-thirties. Political liberals, a group which included secular humanists as well as Protestants and Jews, were the first affected. On the domestic scene, Father Coughlin’s shift to an anti-New Deal position in 1935-36 alerted them to the fascist potentialities of his influence. Over the next few years, their fears were reinforced by his growing extremism on the menace of Communism, his increasingly open anti-Semitism, and the sometimes violent behavior of his “Christian Front” followers, especially in New York City. Internationally, the Spanish Civil War, which broke out in 1936, was the decisive issue. To American liberals, the war was a clear-cut contest between fascism and democracy, and the church had shown its true colors by rallying to the fascists. But most American Catholics, deeply shocked by the widespread desecration of churches and slaughter of priests that marked the early months of the war, saw the struggle as a conflict between Christian civilization and atheistic Communism. They bitterly resented the indifference displayed by American liberals to the persecution of the church in Spain.
Evolutionary Algorithms in Theory and Practice
Authors: Bäck Thomas
Published: November 2020

This book presents a unified view of evolutionary algorithms: the exciting new probabilistic search tools inspired by biological models that have immense potential as practical problem-solvers in a wide variety of settings, academic, commercial, and industrial. In this work, the author compares the three most prominent representatives of evolutionary algorithms: genetic algorithms, evolution strategies, and evolutionary programming. The algorithms are presented within a unified framework, thereby clarifying the similarities and differences of these methods. The author also presents new results regarding the role of mutation and selection in genetic algorithms, showing how mutation seems to be much more important for the performance of genetic algorithms than usually assumed. The interaction of selection and mutation, and the impact of the binary code are further topics of interest. Some of the theoretical results are also confirmed by performing an experiment in meta-evolution on a parallel computer. The meta-algorithm used in this experiment combines components from evolution strategies and genetic algorithms to yield a hybrid capable of handling mixed integer optimization problems. As a detailed description of the algorithms, with practical guidelines for usage and implementation, this work will interest a wide range of researchers in computer science and engineering disciplines, as well as graduate students in these fields.
Virtual Realism
Authors: Heim Michael
Published: November 2020

Virtual reality has introduced what is literally a new dimension of reality to daily life. But it is not without controversy. Indeed, some say that a collision is inevitable between those passionately involved in the computer industry and those increasingly alienated from (and often replaced by) its applications. Opinions range from the cyberpunk attitude of Wired magazine and Bill Gates's commercial optimism to the violent opposition of the Unabomber. Now, with Virtual Realism, readers have a thought-provoking guide to the "cyberspace backlash" debate and the implications of cyberspace for our culture. Michael Heim offers a comprehensive introduction to virtual reality and a provocative commentary on its present and future impact on our lives. Heim describes the fascinating and important industrial and military uses of virtual reality, as well as its artistic and entertainment applications. He argues that we must balance the idealist's enthusiasm for computerized life with the need to ground ourselves more deeply in primary reality. This "uneasy balance" he calls virtual realism.
Operational Constraints in Diagrammatic Reasoning
Authors: Shimojima Atsushi
Published: November 2020

Diagrammatic reasoning is reasoning whose task is partially taken over by operations on diagrams. It consists of two kinds of activities: (i) physical operations, such as drawing and erasing lines, curves, figures, patterns, symbols, through which diagrams come to encode new information (or discard old information), and (ii) extractions of information diagrams, such as interpreting Venn diagrams, statistical graphs, and geographical maps. Given particular tasks of reasoning, different types of diagrams show different degrees of suitedness. For example, Euler diagrams are superior in handling certain problems concerning inclusion and membership among classes and individuals, but they cannot be generally applied to such problems without special provisos. Diagrams make many proofs in geometry shorter and more intuitive, while they take certain precautions of the reasoner’s to be used validly. Tables with particular configurations are better suited than other tables to reason about the train schedule of a station. Different types of geographical maps support different tasks of reasoning about a single mountain area. Mathematicians experience that coming up with the “right” sorts of diagrams is more than half-way to the solution of most complicated problems. Perhaps many of these phenomena are explained with reference to aspect (ii) of diagrammatic reasoning because some types of diagrams lets a reasoner retrieve a kind of information that others do not. or lets the reasoner retrieve it more “easily” than others. In fact, this is the approach that psychologists have traditionally taken. In this chapter, we take a different path and focus on aspect (i) of diagrammatic reasoning. Namely, we look closely at the process in which a reasoner applies operations to diagrams and in which diagrams come to encode new information through these operations. It seems that this process is different in some crucial points from one type of diagrams to another, and that these differences partially explain why some types of diagrams are better suited than others to particular tasks of reasoning.
Diagrams and the Concept of Logical System
Authors: Barwise Jon , Hammer Eric
Published: November 2020

In attempting to analyze the notion of a logical system, there are various approaches that could be taken. One would be to look at the things people have called logical systems and try to develop a natural framework which would encompass most or many of these, and then explore the consequences of the framework, seeing what else falls under the framework and what the consequences of the general notion happen to be. This was basically the approach taken, for example, in Barwise [1974], one of the early attempts to develop such a framework. This approach has much to recommend it, but it also has at least two serious drawbacks. It is too dependent on accidents of history, that is, on what particular systems of logic people happened to have developed. There is at least the theoretical possibility that biases of precedent and fashion have played a significant role in the way things have gone. If so, the abstraction away from practice has the danger of codifying these historicallycontingent biases, making them appear like necessary features of a logical system. The flip side of this problem is that there may well be some unnatural logical systems which contort the framework. But how else could one proceed in an attempt to get a principled notion of logical system? Another approach, the one we take here, is to look at the existing logical systems that people happened to have developed and to try to see what they were up to in more general terms. Our hope is to find some interesting natural phenomenon lurking behind these systems, a “natural kind,” if you will. If there is such a natural phenomenon, it could be used to guide the formulation of an abstract notion of logical system. If a characterization of logical systems could be found using this approach, it would have potentially two significant advantages over the more orthodox approach. First, it would provide a basis from which one could give a principled critique of existing systems claimed to be logical systems. Second, though, it would point out gaps, that is, logical systems which have yet to be developed.
Beyond Hodgkin and Huxley: Calcium and Calcium-Dependent Potassium Currents
Authors: Koch Christof
Published: November 2020

The cornerstone of modern biophysics is the comprehensive analysis by Hodgkin and Huxley (1952a,b,c,d) of the generation and propagation of action potentials in the squid giant axon. The basis of their model is a fast sodium current INa and a delayed potassium current IK (which here we also refer to as IDR)- The last 40 years of research have shown that impulse conduction along axons can be successfully analyzed in terms of one or both of these currents. Nonetheless, their equations do not capture—nor were they intended to capture—a number of important biophysical phenomena, such as adaptation of the firing frequency to long-lasting stimuli or bursting, that is, the generation of two to five spikes within 5-20 msec. Moreover, the transmission of electrical signals within and between neurons involves more than the mere circulation of stereotyped pulses. These impulses must be set up and generated by subthreshold processes. The differences between the firing behavior of most neurons and the squid giant axon reflect the roles of other voltage-dependent ionic conductances than the two described by Hodgkin and Huxley. Over the last two decades, more than several dozen membrane conductances have been characterized (Hagiwara, 1983; Llinás, 1988; Hille, 1992). They differ in principal carrier, voltage, and time dependence, dependence on the presence of intracellular calcium and on their susceptibility to modulation by synaptic inputs and second messengers. Our knowledge of these conductances and the role they play in impulse formation has accelerated rapidly in recent years as a result of various technical innovations such as single-cell isolation, patch clamping, and molecular techniques. We will here describe the most important of these conductances and briefly characterize each one. In order to understand more completely the functional role of these conductances in determining the response of the cell to input, empirical equations that approximate their behavior under physiological conditions must be developed and compared against the physiological preparations. In a remarkable testimony to the power and the generality of the Hodgkin-Huxley approach, the majority of such phenomenological models has used their methodology of describing individual ionic conductances in terms of activating and inactivating particles with first-order kinetics (see Chap. 6).
Chemical Kinetics
Authors: Yung Yuk L. , DeMore William B.
Published: November 2020

It is convenient to distinguish two types of chemistry in the solar system. The first is thermochemical chemistry driven by the thermal energy of the atmosphere. This type of chemistry is important, for example, in the interior of the giant planets where pressures and temperatures exceed 1000 bar and 1000 K, respectively. The second type is disequilibrium chemistry, driven by an external energy source, of which solar radiation is the most important in the solar system. Chemical reactions between stable molecules are very slow at pressures less than 1 bar in planetary atmospheres. Sunlight is the ultimate source of greater chemical activity in the middle and upper atmospheres of planets. As shown in chapter 2, the absorption of solar ultraviolet radiation by atmospheric gases leads to the production of radical species (e.g., atoms, ions, excited molecules) that are extremely reactive. The bulk of atmospheric chemistry involves the reaction between the radicals themselves and between the radicals and stable molecules. In this chapter we briefly survey the chemical kinetics that are important for understanding the chemistry of planetary atmospheres.
Windows into the Earth
Authors: Smith Robert B. , Siegel Lee J.
Published: November 2020

Millions of years ago, the North American continent was dragged over the world's largest continental hotspot, a huge column of hot and molten rock rising from the Earth's interior that traced a 50-mile wide, 500-mile-long path northeastward across Idaho. Generating cataclysmic volcanic eruptions and large earthquakes, the hotspot helped lift the Yellowstone Plateau to more than 7,000 feet and pushed the northern Rockies to new heights, forming unusually large glaciers to carve the landscape. It also created the jewel of the U.S. national park system: Yellowstone. Meanwhile, forces stretching apart the western U.S. created the mountainous glory of Grand Teton National Park. These two parks, with their majestic mountains, dazzling geysers, and picturesque hot springs, are windows into the Earth's interior, revealing the violent power of the dynamic processes within. Smith and Siegel offer expert guidance through this awe-inspiring terrain, bringing to life the grandeur of these geologic phenomena as they reveal the forces that have shaped--and continue to shape--the greater Yellowstone-Teton region. Over seventy illustrations--including fifty-two in full color--illuminate the breathtaking beauty of the landscape, while two final chapters provide driving tours of the parks to help visitors enjoy and understand the regions wonders. Fascinating and informative, this book affords us a striking new perspective on Earth's creative forces.
Fixed Points-Contractive Functions
Authors: Sikorski Krzysztof A.
Published: November 2020

Fixed point computation has been an intensive research area since 1967 when Scarf introduced simplicial algorithm to approximate fixed points. Several algorithms have been invented since then, including restart and homotopy methods. Most of these were designed to approximate fixed points of general maps and used the residual error criterion. In this chapter we consider the absolute and/or relative error criteria for contractive univariate and multivariate functions. The departure of our analysis is the classical Banach fixed point theorem. Namely, we consider a function f : D →D, where D is a closed subset of a Banach space B. We assume that f is contractive with a factor q < 1, i.e., . . . ||f(x) – f(y)|| ≤ q ||x-y||, for all x,y ∈ D. Then, there exists a unique ∝ = ∝ (f) ∈ D such that ∝ is a fixed point of f, ∝ = f (∝)
Complexity
Authors: Pool Robert
Published: November 2020

Things used to be so simple. In the old days, a thousand generations ago or so, human technology wasn’t much more complicated than the twigs stripped of leaves that some chimpanzees use to fish in anthills. A large bone for a club, a pointed stick for digging, a sharp rock to scrape animal skins—such were mankind’s only tools for most of its history. Even after the appearance of more sophisticated, multipiece devices—the bow and arrow, the potter’s wheel, the ox-drawn cart—nothing was difficult to understand or decipher. The logic of a tool was clear upon inspection, or perhaps after a little experimentation. No longer. No single person can comprehend the entire workings of, say, a Boeing 747. Not its pilot, not its maintenance chief, not any of the thousands of engineers who worked upon its design. The aircraft contains six million individual parts assembled into hundreds of components and systems, each with a role to play in getting the 165-ton behemoth from Singapore to San Francisco or Sidney to Saskatoon. There are structural components such as the wings and the six sections that are joined together to form the fuselage. There are the four 21,000-horsepower Pratt & Whitney engines. The landing gear. The radar and navigation systems. The instrumentation and controls. The maintenance computers. The fire-fighting system. The emergency oxygen in case the cabin loses pressure. Understanding how and why just one subassembly works demands years of study, and even so, the comprehension never seems as palpable, as tangible, as real as the feel for flight one gets by building a few hundred paper airplanes and launching them across the schoolyard. Such complexity makes modern technology fundamentally different from anything that has gone before. Large, complex systems such as commercial airliners and nuclear power plants require large, complex organizations for their design, construction, and operation. This opens up the technology to a variety of social and organizational influences, such as the business factors described in chapter 3. More importantly, complex systems are not completely predictable.
Introduction
Authors: Kukulska-Hulme Agnes
Published: November 2020

When asked about the purpose of human language, most people would instinctively reply that its main purpose is communication. Most of us take for granted our ability to communicate easily through language. It would be natural for us, as computer users, to expect the same degree of ease when we interact with systems and user manuals. But even computer professionals and other experienced users are often baffled by the explanations that appear in so-called “help” facilities; perplexed by the meanings of words in menu options, on toolbars, and buttons; and hampered in information retrieval by having to use terms that do not readily express their needs. Words on the computer screen can create a barrier to communication, yet users who turn to help files or documentation are frequently disappointed. Times columnist Lynne Truss speaks for many when, at the end of yet another unrewarding session on her computer, she declared: “I have even stopped looking at those files titled ‘Read This,’ because it’s sad but true; I have never yet opened one whose contents I could understand” (1996). Often, a frustrated cry of “I don’t understand the options on the screen” leads many users to just “try it and see what happens,” with potentially disastrous or time-wasting consequences. “I don’t understand the manuals” is another typical refrain, which provides an excellent reason for not reading them. It has been said so often (e.g., Smith 1992), that alternative ways of informing or teaching users are now being promoted; for instance, video training. This mode of delivery can make information more palatable, but it does not eliminate the problems created by confusing use of language in the user interface. The difficulties experienced by both professional and casual or new users are not inevitable; they are not something to be accepted as a feature of computer systems, manuals, and on-line documentation. Something can be done to improve the way that language is presented and used in these contexts. This book provides the necessary communicative framework as well as practical recommendations to make it possible to significantly improve user interface and documentation design.
Berlin, 1991 Dialectical Dilemmas in the Universities: West Side Story, East Side Story
Authors: Rodden John G.
Published: November 2020

Western Berlin, October 3, 1991. Tag der Einheit: “Unity Day.” The first anniversary celebrating German reunification. Or perhaps “marking” reunification is a more accurate term. No jubilant talk of a New Germany, no flag-waving nearby. My forehead pressed against the cool glass of the third-storey living-room window, I watch a half-dozen skinheads swagger in the street below. “Asylanten Raus!” (“Asylum Seekers Out!”) they chant. “Deutschland den Deutschen!” (“Germany for the Germans!”). Black jeans, jackboots, bomber jackets stabbed with Waffen SS insignias. Dirty blond hair clipped close on the sides, Hitler-style, with a single long forelock. Punk turned political with a vengeance. Waving swastikas, shouting the inevitable yet overwhelming “Sieg Heil!” they’re heading toward the Breitscheidplatz, West Berlin’s central square. Behind me, the Thursday evening news. The sparkle of holiday fireworks gives way to the explosion of terror sweeping across the country. Shelters for asylum seekers torched in Karlsruhe in the southwest and Dusseldorf in the northwest. On the island of Rügen, in the Baltic, a dormitory for refugees razed and incinerated; two Lebanese children severely burned. A hostel for foreigners firebombed in Bremen. “. . . at least 16 racist assaults within 48 hours, bringing the number of attacks to 1,387 since the beginning of the year: the worst outbreak of violence since Hitler’s Germany.” The right-wing German People’s Party, which has just captured an alarming six seats in Bremen’s local elections, does not denounce the violence; its spokesman instead urges immediate restrictions on immigration. A conservative minister pitches Prime Minister Kohl’s proposal to push through a constitutional amendment curbing Germany’s liberal provisions for asylum, which have already opened the doors to more than 1.3 million foreigners since 1989. An interview with historian Golo Mann: “It’s 1933 again.” But dinner is ready. Wolfgang, 44, a wissenschaftlicher Assistent (lecturer) in sociology at the Free University of Berlin, joins me at the window. He takes a long drag of his cigarette. “The Hitler Youth of the ’90s,” Wolfgang says. “German Unity!?! Who knows what this ‘new Germany’ will lead to?” He turns his back on the receding parade of young faschos.
Soil Biology and Microbiology
Authors: Juo Anthony S. R. , Franzluebbers Kathrin
Published: November 2020

Soil organisms are fauna and flora that spend all or part of their life in the soil. They play a vital role in the maintenance of soil fertility through processes such as the accumulation of soil organic matter, soil aggregation, and the mineralization of organic matter which releases nutrients available to higher plants. Moreover, many antibiotics are produced from microorganisms isolated from soils. Soil fauna include macrofauna (> 2 mm in width, such as mice, earthworms, termites, and millipedes), through mesofauna (0.2-2 mm, such as collembola and mites), to microfauna (<0.2 mm, such as nematodes and protozoa). Soil flora include macroflora (such as the roots of higher plants), and microflora (such as algae, fungi, actinomycetes, and bacteria). The activities of soil fauna and flora are intimately related in what ecologists call a food chain or, more accurately, a food web. Higher plants play the role of primary producers by using water and energy from the sun, and carbon from atmospheric carbon dioxide to make organic molecules and living tissues. Soil organisms that eat live plants, such as mice or termites, are called herbivores. Most soil organisms, however, use the debris of dead tissues left by plants and animals (detritus) as their source of food, and are called detritivores. Soil organisms that consume live animals, such as centipedes, mites, spiders, or nematodes, are predators and are called carnivores. Some organisms that live off, but do not consume, other organisms are called parasites. Mycrophytic feeders are organisms that use microflora as their source of food, and include certain collembola, mites, termites, nematodes, and protozoa. The actions of soil fauna in the food web are both physical and chemical, while those of the microflora are mostly biochemical. The actions of mesofauna and macrofauna enhance the activities of the microflora in several ways. First, the chewing action fragments the litter to expose the more easily decomposed cell contents for microbial digestion. Second, the fragmented plant tissues are thoroughly mixed with microorganisms in the animal gut, where conditions are ideal for microbial action. Third, the mobile animals carry microorganisms with them and help them to disperse and find new food sources.
Remediation Research in the Jornada Basin: Past and Future
Authors: Herrick Jeffrey E. , Havstad Kris M.
Published: November 2020

Land degradation in most of the Chihuahuan Desert is characterized by a shift from grass- to shrub-dominated plant communities (Ballín Cortés 1987; Grover and Musick 1990; Fredrickson et al. 1998; see also chapter 10). This shift is associated with increased soil resource redistribution and spatial variability at the plant-interspace scale (Schlesinger et al. 1990; see also chapter 6). Earlier descriptions focused more specifically on the loss of plant species, such as black grama (Bouteloua eriopoda), which were palatable to livestock (Nelson 1934). In 1958, it was estimated that one section (3.2 km2) of black grama grassland could support 18 animal units yearlong, while a similar area dominated by mesquite (Prosopis glandulosa) dunes could support just three animal units (Jornada Experimental Range Staff 1958; see also chapter 13). It was recognized that overgrazing facilitated the increase of less palatable species, including shrubs. Consequently, the objectives of the first organized rangeland research in the Southwest were to identify proper techniques to restore grasslands that had been overgrazed (Jardine and Hurtt 1917; Havstad 1996). Today, we recognize the importance of multiple, interacting factors in addition to overgrazing, and research is more broadly focused on the recovery of ecosystem functions necessary to support multiple ecosystem services. This chapter details this extensive history of research to identify and develop technologies to revegetate, restore, reclaim, rehabilitate, or more generally remediate degraded rangelands. The Society for Ecological Restoration considers that “an ecosystem has recovered when it contains sufficient biotic and abiotic resources to continue its development without assistance or subsidy. It will demonstrate resilience to normal ranges of environmental stress and disturbance. It will interact with contiguous ecosystems in terms of biotic and abiotic flows and cultural interactions” (Society for Ecological Restoration Science and Policy Working Group 2002). Although restoration of perennial grasslands is often cited as the ultimate objective of management intervention in the Southwest, we recognize that in many if not most cases complete restoration of a preexisting plant and animal community is impossible, even if we had perfect knowledge of all of the elements they contained. We also recognize that many of the historic management interventions discussed herein had more limited objectives.
Applications of Remotely Sensed Data from the Jornada Basin
Authors: Rango Albert , Ritchie Jerry
Published: November 2020

Like other rangelands, little application of remote sensing data for measurement and monitoring has taken place within the Jornada Basin. Although remote sensing data in the form of aerial photographs were acquired as far back as 1935 over portions of the Jornada Basin, little reliance was placed on these data. With the launch of Earth resources satellites in 1972, a variety of sensors have been available to collect remote sensing data. These sensors are typically satellite-based but can be used from other platforms including ground-based towers and hand-held apparatus, low-altitude aircraft, and high-altitude aircraft with various resolutions (now as good as 0.61 m) and spectral capabilities. A multispectral, multispatial, and multitemporal remote sensing approach would be ideal for extrapolating ground-based point and plot knowledge to large areas or landscape units viewed from satellite-based platforms. This chapter details development and applications of long-term remotely sensed data sets that are used in concert with other long-term data to provide more comprehensive knowledge for management of rangeland across this basin and as a template for their use for rangeland management in other regions. In concert with the ongoing Jornada Basin research program of ground measurements, in 1995 we began to collect remotely sensed data from ground, airborne, and satellite platforms to provide spatial and temporal data on the physical and biological state of basin rangeland. Data on distribution and reflectance of vegetation were measured on the ground along preestablished transects with detailed vegetation surveys (cover, composition, and height); with hand-held and yoke-mounted spectral and thermal radiometers; from aircraft flown at different elevations with spectral and thermal radiometers, infrared thermal radiometers, multispectral video, digital imagers, and laser altimeters; and from space with Landsat Thematic Mapper (TM), IKONOS, QuickBird, Terra/Aqua, and other satellite-based sensors. These different platforms (ground, aircraft, and satellite) allow evaluation of landscape patterns and states at different scales. One general use of these measurements will be to quantify the hydrologic budget and plant response to changes in components in the water and energy balance at different scales and to evaluate techniques of scaling data.