bluuebunny/crossref_metadata_2025 huggingface dataset:
Ceramics
Authors: Herz Norman , Garrison Ervan G.
Published: November 2020

Archaeological ceramics refers to products made primarily of clay and containing variable amounts of lithic and other materials as well. The term ceramic is derived from the Greek keramos, which has been translated as "earthenware" or "burned stuff." Ceramics include products that have been fired, primarily pottery but also brick, tile, glass, plaster, and cement as well. Since pottery is by far the most important archaeologically, and the methods of sampling and study are largely applicable to the others, this chapter is devoted primarily to pottery. Pottery then is the general term used here for artifacts made entirely or largely of clay and hardened by heat. Today, a distinction is sometimes made between pottery, applied to lower-quality ceramic wares, and the higher-grade product porcelain. No such distinction will be made here, so the term pottery alone will be used. Raw material that goes into the making of a pot includes primarily clay, but also varying amounts of temper, which is added to make the material more manageable and to help preserve the worked shape of the pot during firing. Of primary interest in ceramic studies are 1. the nature and the source of the raw materials—clays, temper, and slip (applied surface pigment)—and a reconstruction of the working methods of ancient potters; 2. the physical properties of the raw materials, from their preparation as a clay-temper body through their transformations during manufacture into a final ceramic product; 3. the nature of the chemical and mineral reactions that take place during firing as a clue to the technology available to the potter; and 4. the uses, provenance, and trade of the wares produced. Much of the information needed to answer these questions is available through standard geochemical and petrographic analysis of ceramic artifacts. Insight into the working methods of ancient potters also has been obtained through ethnographic studies of cultures where, because of isolation or conservative traditions or both, ancient methods have been preserved.
A Foundation for Design
Authors: Blum Bruce I.
Published: November 2020

The underlying thesis of this book is that, although computing technology, in its relatively short lifetime, has clearly impacted modern economies and cultures, our understanding of software remains rooted in our experience with precomputer technology. It follows, therefore, that if we wish to take advantage of software’s unique capabilities, we must begin by reassessing our objectives and constraints. with this renewed understanding serving as a framework, we then can explore alternative paradigms. A revised interpretation is necessary, I assert, because there is a ceiling on the returns available by simply improving the present methods. To attain the level of productivity that software makes possible, we need a new normative model that explains how we ought to develop and employ software. Part III identifies one such normative model, called adaptive design, and demonstrates its efficacy. Yet this is not a book about adaptive design; it is about the mismatch between software’s inherent flexibility and the methods now used in software’s construction. If we are to rectify that disjunction, we must abandon our historical assumptions and reexamine the foundations upon which computer science and software engineering rest. The first two parts of the book are devoted to this reappraisal and foundation building. In Part I, the relationships between science and technology were considered. The discussion was not limited to computers and software. It began by examining the two myths that dominated technological thinking at the time the first digital electronic computers were created; resilient myths that sometimes persist in policy making and academic research. The first myth is that the goal of science is to discover immutable truths about the universe, and the second is that technological advancement depends on the application of this scientific knowledge. These two ideas combine to produce an implicit model of progress: As scientific knowledge accumulates, greater technological advances are enabled. The model is hierarchical. Technological progress follows the discovery of scientific knowledge, and, therefore, technology requires a scientific base to prosper.
Activity, Reflection, Context
Authors: Blum Bruce I.
Published: November 2020

we are almost halfway through the book and this part on design ecology, and I have yet to talk about design, no less software engineering. Is this some kind of shaggy dog story? The kind in which the hero climbs mountains in search of the meaning of life only to have the wise man tell him it is, “The wet bird flies at night.” I hope not. Here is the basic thesis of the book. Computers offer unprecedented power in creating new tools (equipment), but to achieve their potential we must reconstruct how they are used (i.e., shift the paradigm). The first half of the book concerns the foundations upon which we may reconstruct a new software engineering. In the middle of this century, of course, there would be no question as to what that foundation should be: science. But, as I have been trying to show, science and our institutions are in a period of fundamental change. For example, consider what Prigogine, winner of the 1977 Nobel Prize for chemistry, has to say. . . . The classical ... view of science was to regard the world as an “object,” to try to describe the physical world as if it were being seen from the outside as an object of analysis to which we do not belong... The deterministic laws of physics, which were at one point the only acceptable laws, today seem like gross simplifications, nearly a caricature of evolution. . . . Even in physics, as in sociology, only various possible “scenarios” can be predicted. But it is for this very reason that we are participating in a fascinating adventure in which, in the words of Niels Bohr, we are “both spectators and actors.” (1980, pp. xv, xvii) . . . Thus, in only four decades we have moved from physicalism, which sought to impose a physics model on psychology, to a questioning of the very nature of physics itself. As Holland, a physicist, describes our present situation, “we are in a period of transition between two great world views—the universal machine of the classicists and the new holistic universe whose details we are only beginning to glimpse.
Optical Propagation in Solids
Authors: Thomas Michael E.
Published: November 2020

This chapter emphasizes the linear optical properties of solids as a function of frequency and temperature. Such information is basic to understanding the performance of optical fibers, lenses, dielectric and metallic mirrors, window materials, thin films, and solid-state photonic devices in general. Optical properties are comprehensively covered in terms of mathematical models of the complex index of refraction based on those discussed in Chapters 4 and 5. Parameters for these models are listed in Appendix 4. A general review of solid-state properties precedes this development because the choice of an optical material requires consideration of thermal, mechanical, chemical, and physical properties as well. This section introduces the classification of optical materials and surveys other material properties that must be considered as part of total optical system design involving solidstate optics. Solid-state materials can be classified in several ways. The following are relevant to optical materials. Three general classes of solids are insulators, semiconductors, and metals. Insulators and semiconductors are used in a variety of ways, such as lenses, windows materials, fibers, and thin films. Semiconductors are used in electrooptic devices and optical detectors. Metals are used as reflectors and high-pass filters in the ultraviolet. This type of classification is a function of the material’s electronic bandgap. Materials with a large room-temperature bandgap (Eg > 3eV) are insulators. Materials with bandgaps between 0 and 3 eV are semiconductors. Metals have no observable bandgap because the conduction and valence bands overlap. Optical properties change drastically from below the bandgap, where the medium is transparent, to above the bandgap, where the medium is highly reflective and opaque. Thus, knowledge of its location is important. Appendix 4 lists the bandgaps of a wide variety of optical materials. To characterize a medium within the region of transparency requires an understanding of the mechanisms of low-level absorption and scattering. These mechanisms are classified as intrinsic or extrinsic. Intrinsic properties are the fundamental properties of a perfect material, caused by lattice vibrations, electronic transitions, and so on, of the atoms composing the material.
Achieving Spoken Communication with Computers
Authors: Smith Ronnie W. , Hipp D. Richard
Published: November 2020

The most sophisticated and efficient means of communication between humans is spoken natural language (NL). It is a rare circumstance when two people choose to communicate via another means when spoken natural language is possible. Ochsman and Chapanis [OC74] conducted a study involving two person teams solving various problems using restricted means of communication such as typewriting and video, typewriting only, handwriting and video, voice and video, voice only, etc. Their conclusion included the following statement. . . . The single most important decision in the design of a telecommunications link should center around the inclusion of a voice channel. In the solution of factual real-world problems, little else seems to make a demonstrable difference . . . Thus, it would seem desirable to develop computer systems that can also communicate with humans via spoken natural language dialog. Furthermore, recent reports from the research community in speech recognition [Adv93] indicate that accuracy levels in speaker-independent continuous speech recognition have reached a threshold where practical applications of spoken natural language are viable. This book addresses the dialog issues that must be resolved in building effective spoken natural language dialog systems—systems where both the human and computer interact via spoken natural language. We present an architecture for dialog processing for which an implementation in the equipment repair domain has been constructed that exhibits a number of behaviors required for efficient human-machine dialog. These behaviors include the following. • Problem solving to achieve a target goal. • The ability to carry out subdialogs to achieve appropriate subgoals and to pass control arbitrarily from one subdialog to another. • The use of a user model to enable useful verbal exchanges and to inhibit unnecessary ones. • The ability to use context dependent expectations to correct speech recognition and track user movement to new subdialogs. • The ability to vary the task/dialog initiative from strongly computer controlled to strongly user controlled or somewhere in between.
Extending the State of the Art
Authors: Smith Ronnie W. , Hipp D. Richard
Published: November 2020

This book has presented a computational model for integrated dialog processing. The primary contributions of this research follow. • A mechanism (the Missing Axiom Theory) for integrating subtheories that each address an independently studied subproblem of dialog processing (i.e. interactive task processing, the role of language, user modeling, and exploiting dialog expectation for contextual interpretation and plan recognition). • A computational theory for variable initiative behavior that enables a system to vary its responses at any given moment according to its level of initiative. • Detailed experimental results from the usage of a spoken natural language dialog system that illustrate the viability of the theory and identify behavioral differences of users as a function of their experience and initiative level. This chapter provides a concluding critique, which identifies areas of ongoing work and offers some advice for readers interested in developing their own spoken natural language dialog systems. This section describes important issues we did not successfully address in this research because either (1) we studied the problem but do not as yet have a satisfactory answer; or (2) it was not necessary to investigate the problem for the current system. Regardless of the reason, incorporating solutions to these problems is needed to strengthen the overall model. In section 4.7.3 we have already discussed the difficulties in determining when and how to change the level of initiative during a dialog as well as the problems in maintaining coherence when such a change occurs. Ongoing work in this area is being conducted by Guinn [Gui93]. His model for setting the initiative is based on the idea of “evaluating which participant is better capable of directing the solution of a goal by an examination of the user models of the two participants.” He provides a formula for estimating the competence of a dialog participant based on a probabilistic model of the participant’s knowledge about the domain. Using this formula, Guinn has conducted extensive experimental simulations testing four different methods of selecting initiative.
Private, Public, Personal: Americans and the Land
Authors: Worster Donald
Published: November 2020

I Sat down the other night to do something I had not done in a long time: read the United States Constitution. Though a short document, only some twelve or thirteen double-columned pages in most printings, it was writing I had not looked at for over a decade. Yet I am an historian of this country. My excuse is that there is not enough time to read most things even once, and twice or more is out of the question. It is a poor excuse; some things we really ought to read more than once in a lifetime—ought to read every year, like Emily Dickinson’s poetry or Henry Thoreau’s book about that pond in Massachusetts. The Constitution is a piece of writing I would recommend reading no more than once a decade. It hasn’t got much of a plot. The language is clear and easy, but lacks eloquence. Its single great virtue is its plain sensibleness, a virtue that has, with many glaring exceptions, stayed with us and become one of our most attractive national qualities. We like to think we are a level-headed people and that this document epitomizes our level-headedness. In a world that often seems to have gone plumb crazy into one fanaticism or another, the Constitution reassures us with its good sense. We can look back to it with relief that our political system was framed by wise, far-sighted people; and unsure today whether we could improve on their wisdom, we usually leave it alone. Now and then we take the document out and actually read it. There is, however, one glaring omission in the Constitution, so immense and damaging that I believe we ought to try to repair it. Nowhere in all the sections, articles, and amendments is there any mention of the American land and our rights and responsibilities pertaining thereto. I find the word “land” appearing only once, and then it refers to rules governing the capture of prisoners “on Land and Water.”
Aldo Leopold and the Search for an Integrated Theory of Environmental Management
Authors: Norton Bryan G.
Published: November 2020

Aldo Leopold led two lives. He was, in the best tradition of Gifford Pinchot, a forester and a coldly analytic scientific resource manager, devoted to maximizing resource productivity. But Leopold was also a romantic, who joined the Forest Service because of his love for the outdoors, a love he never lost or fully subjugated to the economic “ciphers” that so constrain public conservation work. During the last decade of his life, Leopold the romantic fashioned a little book of essays. He chose from the best of his stacks of field journals and his voluminous publications a few short essays, supplemented these with new pieces, polished them, and strung and restrung them like pearls. The manuscript, representing the essence of his long career, was given final acceptance by Oxford University Press only seven days before Leopold’s death, and the essays were published as A Sand County Almanac. The final essay in that book is “The Land Ethic,” which, Leopold said, “sets forth, in more logical terms, some ideas whereby we dissenters rationalize our dissent.” Although he was not primarily an abstract thinker, Leopold, I will assert, has been the most important figure in the history of both environmental management and environmental ethics. This evaluation is based on one reason: Having faced the environmentalists’ dilemma and, having to formulate goals and actions, he articulated a workable, practical philosophy that transcends the dilemma. The story of how he did so is a sketch of his life. Leopold was a forester in the Southwest for fifteen years. He saw the range deteriorate. He saw the main street of Carson City erode into a deep chasm, and he knew, by the early 1920s, that his agency and its Pinchotist philosophy was significantly responsible. But he was as befuddled as anyone else, and grasped at philosophical straws, or any other straws, to articulate in general terms what was going wrong. Leopold had entered the Forest Service at the height of the Hetch Hetchy controversy. He recognized, of course, that there were critics of the service, and he surely had some respect for Muir’s viewpoint.
Chemical Reaction Kinetics in Solution
Authors: Fawcett W. Ronald
Published: November 2020

The kinetics of chemical reactions were first studied in liquid solutions. These experiments involved mixing two liquids and following the change in the concentration of a reactant or product with time. The concentration was monitored by removing a small sample of the solution and stopping the reaction, for example, by rapidly lowering the temperature, or by following a physical property of the system in situ, for example, its color. Although the experiments were initially limited to slow reactions, they established the basic laws governing the rate at which chemical changes occur. The variables considered included the concentrations of the reactants and of the products, the temperature, and the pressure. Thus, the reacting system was examined using the variables normally considered for a system at equilibrium. Most reactions were found to be complex, that is, to be made up of several elementary steps which involved one or two reactants. As the fundamental concepts of chemical kinetics developed, there was a strong interest in studying chemical reactions in the gas phase. At low pressures the reacting molecules in a gaseous solution are far from one another, and the theoretical description of equilibrium thermodynamic properties was well developed. Thus, the kinetic theory of gases and collision processes was applied first to construct a model for chemical reaction kinetics. This was followed by transition state theory and a more detailed understanding of elementary reactions on the basis of quantum mechanics. Eventually, these concepts were applied to reactions in liquid solutions with consideration of the role of the non-reacting medium, that is, the solvent. An important turning point in reaction kinetics was the development of experimental techniques for studying fast reactions in solution. The first of these was based on flow techniques and extended the time range over which chemical changes could be observed from a few seconds down to a few milliseconds. This was followed by the development of a variety of relaxation techniques, including the temperature jump, pressure jump, and electrical field jump methods. In this way, the time for experimental observation was extended below the nanosecond range.
Flexibility and Function of the Excherichia coli trp Represser
Authors: Gryk M.R. , Jardetzky O.
Published: November 2020

The trp repressor from Escherichia coli is a DNA binding protein, which in the presence of the ami no acid tryptophan inhibits the transcription of at least five operons: trpEDCBA, trpR, aroH, mtr, and aroL (Zubay et al., 1972; Rose et al., 1973; Zurawski et al., 1981; Heatwole and Somerville, 1991, 1992). The ligand-free form (aporepressor) shows only weak binding (KD ~ 106 - 107 M) to DNA, independent of the nucleotide sequence (Carey, 1988; Hurlburt and Yanofsky, 1990). The tryptophan containing form (holorepressor) binds preferentially to specific operator sequences with a much higher binding constant (KD ~ 1010 - 1011 M) (Carey, 1988; Chou et al., 1989; Hurlburt and Yanofsky, 1990). The binding of the repressoris thus regulated by tryptophan, which acts as a corepressor (Rose et al., 1973). With a molecular weight of approximately 25kD, the trp repressoris one of the smallest regulatory systems known, which makes it attractive as a prototype for the study of the molecular mechanism of allosteric regulation. In the twelve years since it was isolated and purified (Joachimiak et al., 1983), it has become one of the most extensively studied allosteric systems. Although Perutz has justly pointed out that the trp repressoris not allosteric in a classical sense (Perutz, 1989), in fact, the control site is too close to the DNA binding site to separate direct and indirect (allosteric) effects, the system does manifest an essential feature of all allosteric control mechanisms - a structural change induced by ligand binding. Structures of both the apo- and the holorepressor have been determined both by x-ray diffraction (Zhang et al., 1987; Schevitz et al., 1985; Lawson et al., 1988) and by NMR (Arrowsmith et al., 1991a; Zhao et al., 1993). Structures of the operator DNA have also been reported (Lefèvre et al., 1987; Shakked et al., 1994a,b), and several structures of operator-repressor complexes are available: two crystal structures (Otwinowski et al., 1988, Lawson and Carey, 1993), and a family of NMR solution structures (Zhang et al., 1994).
NMR of Larger Proteins: Approach to the Structural Analyses of Antibody
Authors: Arata Yoji
Published: November 2020

The first 1H NMR spectrum of a protein, bovine pancreatic ribonuclease, reported in 1957 by Saunders et al. was accounted for by Jardetzky and Jardetzky (1957) in terms of the spectra of the constituent ammo acids. Jardetzky and coworkers continued to report a series of important papers describing the potential usefulness of high-resolution NMR (Roberts and Jardetzky, 1970). Modern NMR of proteins began with the classic paper published in 1968 by Markley, Putter, and Jardetzky, who beautifully demonstrated the possibility of using stable-isotope labeling for the structural analyses of proteins in solution (Markley et al., 1968). Five years before the publication of this paper, Jardetzky gave an important lecture in Tokyo, stressing the importance of NMR particularly in combination with deuterium labeling as a potential solution version of X-ray crystallography for the determination of the three-dimensional structure of proteins (Jardetzky, 1965). The impact of Jardetzky’s contribution was great, eventually leading to the now well-established combination of multidimensional NMR and stable-isotope labeling for the determination of the three-dimensional structure of proteins in solution. High-resolution NMR of biological macromolecules takes advantage of the fact that 1H, 13C, and 15N, all of which are spin 1/2 nuclei, possess long relaxation times, which primarily are due to weak dipole-dipole interactions. Thus, phase memory can be retained long enough to extract relevant information on the spin system by fully making use of multidimensional techniques. This makes high-resolution NMR special as a tool for structural analyses at atomic resolution. By contrast, relaxation times are far shorter in the case of visible, ultraviolet, infrared, and Raman spectroscopy, where much stronger interactions are involved. For this reason no structural analyses at atomic resolution are possible using these types of spectroscopy. However, an increase in the molecular weight eventually creates difficulties in achieving sufficient spectral resolution to be able to separate and assign each of the resonances of a protein. This is due to 1) a limitation of the strength of static magnetic field available and more importantly 2) an unavoidable shortening of relaxation times originating from the slow tumbling motion of the protein molecules in solution.
Geothermometry
Authors: Bethke Craig M.
Published: November 2020

Geothermometry is the use of a fluid’s (or, although not discussed here, a rock’s) chemical composition to estimate the temperature at which it equilibrated in the subsurface. The specialty is important, for example, in exploring for and exploiting geothermal fields, characterizing deep groundwater flow systems, and understanding the genesis of ore deposits. Several chemical geothermometers are in widespread use. The silica geothermometer (Fournier and Rowe, 1966) works because the solubilities of the various silica minerals (e.g., quartz and chalcedony, SiO2) increase monotonically with temperature. The concentration of dissolved silica, therefore, defines a unique equilibrium temperature for each silica mineral. The Na-K (White, 1970) and Na-K-Ca (Fournier and Truesdell, 1973) geothermometers take advantage of the fact that the equilibrium points of cation exchange reactions among various minerals (principally, the feldspars) vary with temperature. In applying these methods, it is necessary to make a number of assumptions or corrections (e.g., Fournier, 1977). First, the minerals with which the fluid reacted must be known. Applying the silica geothermometer assuming equilibrium with quartz, for example, would not give the correct result if the fluid’s silica content is controlled by reaction with chalcedony. Second, the fluid must have attained equilibrium with these minerals. Many studies have suggested that equilibrium is commonly approached in geothermal systems, especially for ancient waters at high temperature, but this may not be the case in young sedimentary basins like the Gulf of Mexico basin (Land and Macpherson, 1992). Third, the fluid’s composition must not have been altered by separation of a gas phase, mineral precipitation, or mixing with other fluids. Finally, corrections may be needed to account for the influence of certain dissolved components, including CO2 and Mg++, which affect the equilibrium composition (Paces, 1975; Fournier and Potter, 1979; Giggenbach, 1988). Using geochemical modeling, we can apply chemical geothermometry in a more generalized manner. By utilizing the entire chemical analysis rather than just a portion of it, we avoid some of the restricting assumptions mentioned in the preceding paragraph (see Michard et al., 1981; Michard and Roekens, 1983; and especially Reed and Spycher, 1984). Having constructed a theoretical model of the fluid in question, we can calculate the saturation state of each mineral in the database, noting the temperature at which each is in equilibrium with the fluid.
Previous Approaches to Understanding CASE Tool Integration
Authors: Brown Alan W. , Carney David J. , Morris Edwin J. , Smith Dennis B. , Zarrella Paul F.
Published: November 2020

CASE tools typically support individual users in the automation of some task within a software development process. Used thus, CASE tools have undoubtedly helped many organizations in their efforts to develop better quality software to budget and within predicted time scales. Further, if tool technology matures according to the current expectations of many industry analysts, then CASE tools offer the potential to revolutionize the way in which much of our software is currently developed. However, the success of integrated sets of CASE tools — i.e., CASE environment — is a more complex issue. The potential for success is great, but is dependent on many factors. Perhaps the most urgent need is for an improved indepth understanding of the meaning and role of integration in a CASE environment. This is important because it will form the foundation for many of the tasks that will follow. For example, without a common understanding of inte gration, we will continue to struggle to have the necessary shared concepts and terminology to allow integration products to be described and compared, standard interfaces to CASE environment components to be agreed upon, and objective measures of the effectiveness of integration approaches to be produced. The focus of this chapter is a review of previous approaches toward defining a common understanding of integration in a CASE environment. We begin by examining the conceptual models of integration that have been developed and that help to understand the main concepts being addressed in an integrated CASE environment. We then look at the main architectural approaches that have been used in constructing a CASE environment, concentrating on the integration that is supported by those architectures. The problem of integrating software components to produce a CASE environment is the central focus of this book. It is a problem that has resisted easy solution and offers a highly difficult challenge to the software community. In attempting to resolve some of the complex issues in CASE tool integration, researchers have sought a conceptual framework through which these issues can be more easily understood and communicated between different people.
Control Integration Mechanisms
Authors: Brown Alan W. , Carney David J. , Morris Edwin J. , Smith Dennis B. , Zarrella Paul F.
Published: November 2020

Controlling and coordinating tool interactions in a CASE environment require an approach to tool integration that is sufficiently flexible and adaptable to suit different user needs, as well as simple and efficient. These conditions will ensure that new tools can easily be integrated and that their productivity is not significantly impaired. As discussed in the previous chapter, one traditional approach toward tool integration has been based on data sharing, often through a common database in which all tools deposit their data. While this approach can provide a high level of control and coordination between tools, it also imposes a significant overhead on the tools, both because of poor performance of existing database mechanisms when used in this way, and because of the necessary agreement required between the tools to define a common syntax and semantics for their data (e.g., a common data schema). Another approach to integration has been called the control integration approach. This approach is based on viewing a CASE environment as a collection of services provided by different tools. Actions carried out by a tool are announced to other tools via control signals. The tools receiving such signals can decide if the other tool’s actions require that they take any actions themselves. For example, when an editing tool announces that changes have been made to a source file, a build tool may receive this information and initiate a new system build. In addition, one tool may directly request that another tool perform an action by sending it a control signal. For example, the build tool may request that the source file be compiled by a particular compiler. Hence, the primary means of coordination between tools is through the sending and receiving of control signals. In the rest of this chapter, we examine the notion of control integration in a CASE environment, review a number of existing systems, and analyze those systems to identify their differences and to reveal interesting future directions for this work. The reviewed systems do not represent an exhaustive examination of systems implementing a control integration approach.
Integration of CASE Tools with CM Systems: Lessons Learned
Authors: Brown Alan W. , Carney David J. , Morris Edwin J. , Smith Dennis B. , Zarrella Paul F.
Published: November 2020

The problem of CASE tool integration has several concerns that overlap with those of configuration management (CM), so much so that a discussion of one topic is often difficult to separate from a discussion of the other. To illustrate, we note that when choosing a solution to a problem in configuration management, we often must make choices that involve understanding process requirements, examining the services available (and their semantics), and analyzing implementation constraints. We also note that these activities are done simultaneously with making design trade-off decisions related to the integration of these process, service, and mechanism concepts. These factors are applicable to CM, but are not particular to CM: most of these same issues underlie any set of decisions one makes about combining a set of CASE tools into an integrated environment. However, CM and its relationship to CASE tool integration in general poses a unique set of problems. This is most apparent when we realize that CM is sometimes considered as a service (or set of services) provided by the environment or its framework, sometimes as a service provided by a separate stand-alone tool, and sometimes as an integral aspect of each individual CASE tool. These competing views lead to overlaps in functionality and responsibility between individual tools and the environment’s (or framework’s) CM capabilities. For instance: • A fundamental issue for CM is data redundancy. This results when different tools store the same data in separate repositories. Correspondingly, different data models may make data sharing (a fundamental issue for tool integration) difficult. • Version management (VM) and CM services provided by individual tools are frequently linked with private tool data model and data management services. These VM and CM services are not always delegable — sometimes these services are an intricate part of tool function (e.g., for multi-user support and build). • The VM and CM services provided by individual tools may imply or enforce vendor-specific VM/CM policies, as opposed to the CM policies of the environment.
Vectors
Authors: Oertel Gerhard
Published: November 2020

The reader, even if familiar with vectors, will find it useful to work through this chapter because it introduces notation that will be used throughout this book. We will take vectors to be entities that possess magnitude, orientation, and sense in three-dimensional space. Graphically, we will represent them as arrows with the sense from tail to head, magnitude proportional to the length, and orientation indicated by the angles they form with a given set of reference directions. Two different kinds of symbol will be used to designate vectors algebraically, boldface letters (and the boldface number zero for a vector of zero magnitude), and subscripted letters to be introduced later. The first problems deal with simple vector geometry and its algebraic representation. Multiplying a vector by a scalar affects only its magnitude (length) without changing its direction. Problem 1. State the necessary and sufficient conditions for the three vectors A, B, and C to form a triangle. (Problems 1–9, 12–14, 19–23, and 25 from Sokolnikoff & Redheffer, 1958.) Problem 2. Given the sum S = A + B and the difference D = A – B, find A and B in terms of S and D (a) graphically and (b) algebraically. Problem 3. (a) State the unit vector a with the same direction as a nonzero vector A. (b) Let two nonzero vectors A and B issue from the same point, forming an angle between them; using the result of (a), find a vector that bisects this angle. Problem 4. Using vector methods, show that a line from one of the vertices of a parallelogram to the midpoint of one of the nonadjacent sides trisects one of the diagonals. Two vectors are said to form with each other two distinct products: a scalar, the dot product, and a vector, the cross product.
Insects and Spiders
Authors: Hanson Paul
Published: November 2020

Arthropods (e.g., insects, spiders, mites, crustaceans) are the most diverse group of organisms in the biosphere. Several families of insects (e.g., staphylinid beetles, ichneumonid wasps) contain more species than all vertebrates combined. Most arthropods do not yet have scientific names. Little is known about the life histories of most species. The insects of Costa Rica and neighboring Panama have received more attention than any other tropical region of comparable size, but it is mainly limited to species descriptions and distribution records. I and colleagues who have contributed subsections throughout this chapter draw upon the published studies from Monteverde, but no attempt has been made to list all insect species reported from Monteverde. This chapter differs from others in that some contributors focus on tropical cloud forests in general rather than on only Monteverde. The justification is that for most insects, altitude is the single most important factor determining distribution. Most species show widespread geographic distributions but restricted altitudinal distributions. One intensively sampled cloud forest in Costa Rica is Zurqui de Moravia (1600 m), from which considerable information is drawn for this chapter. We have included most of the insect groups that have been studied in Monteverde: spittlebugs, treehoppers, rove beetles, scarab beetles, longhorn beetles, butterflies, social wasps, ants, and bees. Major orders of insects not included from this chapter are mayflies, cockroaches, termites, earwigs, barklice, thrips, and lacewings. Termites and other social insects are less prominent in cloud forests than in lowland forests. Spiders are the only noninsect arthropods included; the information is from a cloud forest at a similar elevation in Colombia. Cloud forests are defined here as forests higher than 1200 m. Our knowledge of cloud forest arthropods is so fragmentary that generalizations are premature. This chapter provides preliminary information on natural history to stimulate entomologists to consider cloud forests as distinct from lowland rain forests. We include practical information on the conservation of cloud forest arthropods, many of which are vital components of the ecosystem.
Stirring and Mixing Effects
Authors: Epstein Irving R. , Pojman John A.
Published: November 2020

In almost everything that we have discussed so far, we have assumed, explicitly or implicitly, either that the systems we are looking at are perfectly mixed or that they are not mixed at all. In the former case, concentrations are the same everywhere in the system, so that ordinary differential equations for the evolution of the concentrations in time provide an appropriate description for the system. There are no spatial variables; in terms of geometry, the system is effectively zero-dimensional. At the other extreme, we have unstirred systems. Here, concentrations can vary throughout the system, position is a key independent variable, and diffusion plays an essential role, leading to the development of waves and patterns. Geometrically, the system is three-dimensional, though for mathematical convenience, or because one length is very different from the other two, we may be able to approximate it as one- or two-dimensional. In reality, we hardly ever find either extreme—that of perfect mixing or that of pure, unmixed diffusion. In the laboratory, where experiments in beakers or CSTRs are typically stirred at hundreds of revolutions per minute, we shall see that there is overwhelming evidence that, even if efforts are made to improve the mixing efficiency, significant concentration gradients arise and persist. Increasing the stirring rate helps somewhat, but beyond about 2000 rpm, cavitation (the formation of stirring-induced bubbles in the solution) begins to set in. Even close to this limit, mixing is not perfect. In unstirred aqueous systems, as we have seen in Chapter 9, it is difficult to avoid convective mixing. Preventing small amounts of mechanically induced mixing requires considerable effort in isolating the system from external vibrations, even those caused by the occasional truck making a delivery to the laboratory stockroom. It is possible to suppress the effects of convection and mechanical motion in highly viscous media, such as the gels used in the experiments on Turing patterns as discussed in the previous chapter. There, we can finally study a pure reaction-diffusion system. Systems in nature—the oceans, the atmosphere, a living cell—are important examples in which chemical reactions with nonlinear kinetics occur under conditions of imperfect mixing.
Sequence, Salt, Charge, and the Stability of DNA at High Pressure
Authors: Macgregor Jr Robert B. , Wu John Q.
Published: November 2020

The effect of pressure on the helix-coil transition temperature (Tm) is reported for the double-stranded polymers poly(dA)poly(dT), poly[d(A-T)], poly[d(l-C], and poly[d(G-C] and triple-stranded poly(dA)2poly(dT). The Tm increases as a function of pressure, implying a positive volume change for the transition and leading to the conclusion that the molar volume of the coil form is larger than the molar volume of the helix. From the change in Tm as a function of pressure, molar volume changes of the transition (ΔVt) are calculated using the Clapeyron equation and calorimetrically determined enthalpies. For the doublestranded polymers, ΔVt, increases in the order poly[d(l-C] < polyt[d(A-T)] < poly(dA)-poly(dT) < polylcl(G-C)]. The value of ΔVt, for the triple-stranded to single-stranded transition of poly(dA) 2poly(dT) is larger than that of poly[d(G-C)I. The magnitude of ΔVt increases with salt concentration in all cases studied; however, the change of ΔVt with salt concentration depends on the sequence of the DNA and the number of strands involved in the transition. In the model proposed to explain the results, the overall molar volume change of the transition is a function of a negative volume change arising from changes in the electrostatic interactions of the DNA strands, and a positive volume change due to unstacking the bases. The model predicted the direction of the change in the ΔVt for several experiments. The magnitude of AVJ increases with counter ion radius, thus for polyld(A-T)], ΔVt, increases in the series Na+ , K+, Cs+, The ΔVt also increases if the charge on the phosphodiester groups is removed. The kinetics of the formation of double-stranded (dA)19(dT)19 in 50 mM NaCI are slowed approximately 14-fold at 200 MPa relative to atmospheric pressure. The implied volume of activation of +37 ml mol−l in the direction of this change is also in agreement with the proposed model. The stability of double- and triple-stranded DNA helices in water around neutral pH depends on the base composition and sequence, as well as on the ionic strength of the solution. Each of these dependencies also defines how DNA interacts with water.
Electrostatic Adsorption of Anions
Authors: Ji G. L.
Published: November 2020

Electrostatic adsorption of anions is one of the important characteristics of variable charge soils. This is caused by the fundamental feature that these soils carry a large quantity of positive surface charge. However, because these soils carry positive as well as negative surface charges, they may exert both attractive and repulsive forces on anions. Therefore, the situation in the adsorption of anions by these soils may be quite complex. There may also be the occurrence of negative adsorption of anions. Besides, for some anion species both electrostatic force and specific force may be involved during their interactions with variable charge soils. As shall be seen in this chapter, such specific force may be operative even for some anion species such as chloride that are generally considered as solely electrostatic in nature during adsorption. Because of historical reasons, the literature on electrostatic adsorption of anions by soils is very limited. Nevertheless, as shall be seen in this chapter, the topic is of interest in both theory and practice. In the present chapter, adsorption of anions shall be discussed mainly from the viewpoint of electrostatic adsorption. The other type of adsorption, specific adsorption or coordination adsorption, shall be dealt with in Chapter 6. The radius of anions is generally much larger than that of cations. Thus, the charge density on anions would be low. When hydrated, because of the smaller ion-dipole force exerted on water molecules, anions are less hydrated than cations. This can be seen in Table 4.1. The rH/rc ratio for cations ranges from 2.22 to 6.37, while that for anions is smaller than 2 except for F-. The orientation of water molecules around anions, especially in the primary hydration region, is also different from that around cations (Conway, 1981). Because of the small rH/rc ratio, hydration does not induce the change in order of size when anions of the same valency are compared. For example, the crystal radii of Cl-, NO3-, and ClO4- are 0.181, 0.264, and 0.292 nm, respectively, while the hydrated radii of these ions are 0.332, 0.335, and 0.338, respectively.
Lime Potential
Authors: Wang J. H.
Published: November 2020

The properties of hydrogen and aluminum ions have been examined in Chapters 10 and 11. These two ion species are ions that directly induce the acid reaction in soils. In soils devoid of soluble salts, the content of cations is constant and the negative surface charges are saturated by, besides hydrogen and aluminum ions, alkali metal and alkaline earth metal ions. These ions are called base ions. The acidity of a soil is determined chiefly by the ratio of the quantity of hydrogen and aluminum ions to that of base ions. Among these base ions, calcium ions occupy the most important position, because they generally account for 65-80% of the total amount of base ions in variable charge soils. Therefore, calcium is an ion species closely related to the acidity of soils. In addition to the parameter pH that directly reflects the concentration of hydrogen ions, one other desirable way is to find a parameter that can reflect the ratio of the hydrogen ions to the calcium ions. This parameter is the lime potential. Since the introduction of the concept of lime potential 40 years ago, little practical application has been made in soil science, although some further theoretical considerations were advanced in the 1950s and the 1960s. Actually, as shall be seen in this chapter, for strongly acid soils, such as variable charge soils, because the quantity of hydrogen ions is too high and at the same time the quantity of calcium ions is too low, lime potential that can reflect the relative ratio of these two ion species is of significance not only in theory but also in practice. The mathematical expression of lime potential is pH-0.5pCa. Lime potential is a simple function of the chemical potential of calcium hydroxide, lime. Hence it may be called lime potential. The physical meaning of pH-0.5pCa can be derived as follows.