bluuebunny/crossref_metadata_2025 huggingface dataset:
Multi-Fluid Transport/Reaction Models with Application in the Modeling of Weakly Ionized Plasma Dynamics
Authors: Beris Antony N. , Edwards Brian J.
Published: November 2020

The industrial use of low-ambient-temperature, weakly ionized plasmas as a reaction environment is growing rapidly. This is primarily evident in the manufacturing technologies of advanced materials, such as the ones used in micro-electronic devices [Jensen, 1987]. The advantages of the plasma environment are due primarily to the presence of high energy electrons which allow high energy chemistry to take place at low ambient temperatures. An example is the successful plasma-enhanced chemical vapor deposition of silicon nitride at temperatures as low as 250-350°C versus temperatures in the range of 700-900°C required for thermal deposition [Reif, 1984]. Thus emerges a need for modeling of the reaction chemistry and the transport phenomena within complex, multicomponent, charged-particle systems, under the influence of externally-imposed electric and magnetic fields. The present chapter addresses this need within the framework of a multi-fluid reactive continuum [Woods, 1975, ch. 9]. Multi-fluid continuum descriptions have arisen as a natural generalization of multicomponent systems in order to account for the absence of momentum and/or energy equilibria between different species populations within the same system [Enz, 1974; Woods, 1975, ch. 9]. The key underlying assumption is that of interpenetrating continua: each one of the mutually interacting, constituent subsystems is characterized as a separate continuum with its own (macroscopic) state variables. Hidden within this assumption is the local equilibrium hypothesis, not between different subsystems—that would have resulted in the more traditional multicomponent description—but within each subsystem in order for the description of each subsystem using (equilibrium) state variables to be meaningful. This is both an asset and a liability of the multi-fluid approach: an asset, because the whole framework of equilibrium thermodynamics is still applicable at the subsystem level, resulting, among other things, in a description requiring only a few well-defined macroscopic state variables; a liability, because it places very stringent requirements on the type of systems to which this theory can be applied. The multi-fluid approach is valid only for phenomena with characteristic time scales much larger than the time scale for each subsystem to reach internal (local) thermodynamic equilibrium.
Appendixes
Authors: Furbish David Jon
Published: November 2020

Definitions and formulae used at various points in the text to manipulate vectors are listed below. Additional useful formulae, including geometrical and physical interpretations complementary to those provided in this text, can be found in standard texts on vector analysis and in mathematical handbooks. The Standard Mathematical Tables published by CRC Press (Boca Raton, Florida) is a particularly handy resource, and most college-level calculus texts cover introductory vector analysis as part of the material intended for a third-semester course. Appendix A in Bird, Stewart, and Lightfoot (1960) is a very good summary of vector and tensor notation presented in the context of fluid mechanics. Section 17.1.1 begins with several basic definitions of vector quantities that generally apply to any orthogonal coordinate system. The notation for unit vectors in Cartesian coordinates, i, j, and k, are used in this section, but it is understood that this notation may be directly replaced with symbols for unit vectors associated with other orthogonal coordinates. Section 17.1.2 then covers differential operations for Cartesian coordinates. Although the notation used for these differential operations in Cartesian coordinates is the same as that for other coordinate systems, the actual operations connoted by the notation are different, and must be defined separately (Appendix 17.2). Let S and T denote scalar functions, and let U, V, and W denote vectors. If U = 〈U1, U2, U3〉, then . . . U = U1i + U2j + U3k . . . . . . (17.1) . . .
Evolution and Cognitive Development
Authors: Siegler Robert S.
Published: November 2020

The central argument of this chapter is that concepts that have helped biologists understand the evolution of species can also help cognitive developmentalists understand the growth of children’s thinking. This argument rests on four main points, corresponding to the four main sections of the chapter. The first point is that current theories of cognitive development are limited by lack of understanding of change mechanisms. The second point is that the problem of explaining the evolution of species has important commonalities with the problem of explaining changes in children’s thinking. The third point is that explanations emphasizing variation, self-regulation, adaptive change, and inheritance have proved useful in understanding biological evolution. The fourth point is that these same concepts are implicitly present in a number of the most promising mechanisms that have been proposed to account for cognitive-developmental change, and that it may be generally useful to try to understand cognitive-developmental change in terms of them. The rest of this chapter elaborates these themes. At present, there is no dominant theory of cognitive development. The limitations of the major theories in the area—Piagetian, neo-Piagetian, Vygotskian, information processing, social learning, ethological, and neo-nativistic—are sufficiently large and apparent that none of them can claim the adherence of anything like a majority of investigators. In all likelihood, the greatest number of developmentalists see themselves as eclectic, borrowing concepts from many theories, but not being entirely comfortable with any one of them. After reviewing current theories of development, Miller (1993) concluded that they share three weaknesses: overly narrow scope, uncertain ecological validity, and inadequate accounts of developmental mechanisms. Of these, the inadequate accounts of developmental mechanisms seems the fundamental limitation. A better understanding of mechanisms would contribute to overcoming the other two problems; it would expand the range of phenomena that could be understood as products of the same underlying mechanisms, and these would likely include everyday as well as laboratory phenomena. The converse does not seem likely: The vast accumulation of data we already possess has generated only limited progress in understanding mechanisms, and it is difficult to see how a broader range of data and/or more ecologically valid data would change the situation much.
Living within Limits
Authors: Hardin Garrett
Published: November 2020

We fail to mandate economic sanity, writes Garrett Hardin, "because our brains are addled by...compassion." With such startling assertions, Hardin has cut a swathe through the field of ecology for decades, winning a reputation as a fearless and original thinker. A prominent biologist, ecological philosopher, and keen student of human population control, Hardin now offers the finest summation of his work to date, with an eloquent argument for accepting the limits of the earth's resources--and the hard choices we must make to live within them. In Living Within Limits, Hardin focuses on the neglected problem of overpopulation, making a forceful case for dramatically changing the way we live in and manage our world. Our world itself, he writes, is in the dilemma of the lifeboat: it can only hold a certain number of people before it sinks--not everyone can be saved. The old idea of progress and limitless growth misses the point that the earth (and each part of it) has a limited carrying capacity; sentimentality should not cloud our ability to take necessary steps to limit population. But Hardin refutes the notion that goodwill and voluntary restraints will be enough. Instead, nations where population is growing must suffer the consequences alone. Too often, he writes, we operate on the faulty principle of shared costs matched with private profits. In Hardin's famous essay, "The Tragedy of the Commons," he showed how a village common pasture suffers from overgrazing because each villager puts as many cattle on it as possible--since the costs of grazing are shared by everyone, but the profits go to the individual. The metaphor applies to global ecology, he argues, making a powerful case for closed borders and an end to immigration from poor nations to rich ones. "The production of human beings is the result of very localized human actions; corrective action must be local....Globalizing the 'population problem' would only ensure that it would never be solved." Hardin does not shrink from the startling implications of his argument, as he criticizes the shipment of food to overpopulated regions and asserts that coercion in population control is inevitable. But he also proposes a free flow of information across boundaries, to allow each state to help itself. "The time-honored practice of pollute and move on is no longer acceptable," Hardin tells us. We now fill the globe, and we have no where else to go. In this powerful book, one of our leading ecological philosophers points out the hard choices we must make--and the solutions we have been afraid to consider.
Uneasy Litter Mates: Population and Progress
Authors: Hardin Garrett
Published: November 2020

In the fifth century B.C., Herodotus reported that there had been a time when a person could walk across North Africa from the Atlantic to the Indian Ocean and be always in the shade of trees. No more: the land was well on the way to becoming the desert we know today. Herodotus generalized: "Man stalks across the landscape, and deserts follow in his footsteps." In the tenth century A.D., a Samanid prince identified four earthly paradises: the regions of Samarkand, southern Persia, southern Iraq, and Damascus. No one who has visited any of these sites now would dream of calling it a paradise. They have been cursed with wars, but warfare is only a secondary cause of their degradation. Throughout history human exploitation of the earth has produced this progression: colonize—destroy—move on. When the Pollyannas write history they focus only on the first of these three actions, the desirable effects of which were most evident during the rapid colonization of the New World. In 1845 a now obscure American journalist coined a deathless phrase when he spoke of "the fulfillment of our manifest destiny to overspread the continent allotted by Providence." "Manifest destiny" is one of those catchphrases we love. We would not welcome the words of a journalist who identified colonization as but a prelude to destruction and abandonment. The restless "moving on" of the human species has depended on always having fresh land to move to. Optimists are not easily frightened by the results, of course: as late as 1980 one Pollyanna brightly explained how all turned out for the best in this best of all possible worlds: "Each year deserts the world over engulf an area the size of Massachusetts. A great deal of land lost is agricultural. . . . Fortunately, however, land is always being replaced or coming under cultivation to make up for land lost." An ecologist—ever guided by the question "And then what?"—would insist on a clarification of the above quotation: Does "always" mean "forever"? If so, it implies that there are no limits to earthly space. It is not surprising that ecologists are not the most popular of people in a growth-oriented economy.
Cowboy Economics versus Spaceship Ecology
Authors: Hardin Garrett
Published: November 2020

Europe-focused histories present the world as it appeared to Europeans and to the cultures derived from that continent. It is said that the New World was discovered in 1492—a statement that would have surprised the Aztecs had they heard it. Adopting for the moment the Eurocentric point of view, we note that whereas before 1492 there were about 24 acres of Europe per European, afterward there were some 120 acres of land per European. The fivefold increase presumes the legitimacy of property gained by conquest. This sudden wealth led to what W. P. Webb called an "age of exuberance." No wonder, as Catton and Riley remarked, "Opportunities thereafter seemed limitless. . . [and] it is not surprising that an optimistic belief in 'progress' developed." The age of exuberance has lasted for over four centuries, but seems to be drawing to a close as the sixth century looms on the horizon. Epicurus proclaimed two important default positions: (1) nothing can be created out of nothing, and (2) no existing thing can be converted into nothingness. These are universally accepted by natural scientists, who view them as conservative statements since they refer to the conservation of things. Are economists conservative, in this sense? The record is mixed. Economists demand that their helpers, the accountants, balance their books exactly; and an economist is likely to tell his beginning students that "There's no such thing as a free lunch." But before the course is far advanced the conservative sense of this incantation seems often to be forgotten. The manmade complexities of the world of finance make it difficult to recognize the underlying conservation of true wealth. Scientists have had an easier time dealing with matter and energy. By 1879 the conservation of these entities had been well established in the natural sciences, but in that year the "single taxer" Henry George (1839-1897) defiantly proclaimed non-conservation in the social sciences (see Box 7-1). Real estate developers and commercial promoters in general still sing George's song.
Limits: A Constrained View
Authors: Hardin Garrett
Published: November 2020

In the real world—beyond pedagogy, beyond hypocrisy—language has two purposes: to facilitate thought, and to prevent it. Seldom does a writer skilled in the arts of persuasion call attention to the second purpose because to do so would be to arouse suspicions of his own verbalizations. Rhetoric—ambiguous, deceptive, delusive rhetoric—stands ever ready to help writers of all persuasions to "throw dust in the jurymen's eyes." Population pundits use this tactic when they entitle an article or book "Standing Room Only." In getting the reader's attention those three words substitute trivia for fundamentals. Before another work with that title is published let's see why "Standing Room Only" is so silly. How much of the earth's land area would now be occupied if the present five billion inhabitants were crowded together on a "standing room only" basis? Taking the space occupied by the average human being, standing up, as three square feet (a rectangle 3 X 1 feet), a square mile could accommodate just a little more than 9 million standees. Five billion people (the population of the earth in 1987) could be accommodated on a mere 556 square miles, just 46 percent of the area of Rhode Island, our smallest state. A perfect square, 24 miles on a side, could accommodate the world's entire population, standing up. Alaska, with an SRO capacity of 5 trillion, could accommodate a thousand times the present world population. Let's look at some more absurd statistics. If all the land area of the earth were covered by SRO patrons, what would be the total population? And how long would it take the present population to reach that figure, if the recent rate of world population increase (1.7 percent per year) could be maintained? The earth's land area (1.48 X 1014 square meters) divided by the area occupied by one person (0.28 square meters) = 5.29 X 1014, or 529 trillion human beings. It would take 5 billion people, increasing at 1.7 percent per year, just 686 years to swell to that number. That time lapse is only 34 percent as great as the total Christian era to date.
The Benign Demographic Transition
Authors: Hardin Garrett
Published: November 2020

The child survival hypothesis is immensely popular with politicians, religious leaders, and executives of organizations engaged in foreign philanthropy, because it justifies the anti-Malthusian and tender-minded belief that reducing infant mortality will automatically bring about a reduction in fertility. The belief easily converts into policy, because saving babies is something we know how to do. Nonetheless, the term child survival hypothesis is not widely known outside professional circles. By contrast, the theory of the "demographic transition" has been extensively popularized over several decades. Its meaning can, however, stand a bit of clarification. The theory was born French: in 1934 Adolphe Landry wrote of the revolution demographique.' A decade later this was translated into the familiar English form. By 1969 a widely used population textbook expressed the common, if not the predominant, opinion of demographers when it identified the theory as "one of the best documented generalizations in the social sciences." Documented it certainly is: the literature is appallingly large. But documented does not mean proved. Ironically (in the words of demographer Michael Teitelbaum), "its explanatory power has come into increasing scientific doubt at the very time that it is achieving its greatest acceptance by nonscientists. In scientific circles, only modest claims are now made for transition theory." That was said in 1975. Ten years later Teitelbaum and Winter put the matter more forcefully: "It is doubtful whether this theory was ever truly a theory at all (that is, a set of hypotheses with predictive force)." Before we look into its predictive abilities we need to find out exactly what the theory asserts. This is not easy because the theory is almost never carefully and rigorously described. We need once more to call upon the art of graphing. Transition theory assumes a finite world. For most of the world, most of the time, both birth rate and death rate have been in the neighborhood of 40 per thousand population per year.5 When the two rates are equal, ZPG (zero population growth) prevails. Despite perennial fluctuations in population size at different locations, the average growth rate of the entire human population for the past million years has been very close to ZPG, namely 0.02 percent per year. At this growth rate the population doubles every 3,500 years—hardly a population explosion!
Major Default Positions of Human Biology
Authors: Hardin Garrett
Published: November 2020

In Chapter 5 it was shown that physics, generally accepted as the very model of a rigorous discipline, cannot escape common-sense assertions that are supported by nothing more than "a conviction of the mind," to use the words of E. T. Whittaker. On this apparently fragile foundation have been erected powerful sciences and fruitful technologies. The biological sciences also rest on the common sense of a few default positions. Human behavior being as variable as it is, human biology must deal with a great mass of data. The classical error of Post hoc ergo propter hoc—"after this, therefore because of this"—lies ever in wait for those who are too trusting of empirical studies. Thus it came about (as we saw in Chapter 16) that the benign demographic transition theory managed to survive for nearly half a century, though it was implausible in principle and unprovable in practice. Tools of investigation can serve pathological goals. Psychiatrists have long recognized the abnormality called "logorrhea"—verbal diarrhea, or diarrhea of the larynx. Statistical analysis can develop into a similar disease. The opaqueness of statistical arguments makes it easy for analysts to "get away with murder." In befuddling the public, logorrhea has been joined by "arithmorrhea," number diarrhea. Statistics, though often wonderfully useful, can also serve as a substitute for thought. The default positions of biology, like those of the physical sciences, place a heavy burden of proof on any assertion that violates common sense. Of course, the default status must be assigned with discriminating care, or serious errors will be made. For a cautionary instance consider these remarks by an early nineteenthcentury critic of Malthus: "Everywhere [man's] length of life, the chances of his existence are nearly the same.... The ratio of our increase, the proportion of our mortality, appear to be amongst the most unalterable laws of our nature; they depend on no accidents; they are not influenced, they cannot be, by any human institution."1 Even the most casual observations of health, length of life, and fertility in various regions of the world should have shown the author that he had chosen his default position unwisely.
Population Control: Natural versus Human
Authors: Hardin Garrett
Published: November 2020

Were we able to talk with other animals, it is extremely unlikely that we should hear them debating the problem of population control. They don't need to debate: nature solves the problem for them. And what is the problem? Simply this: to keep a successful species from being too successful. To keep it from eating itself out of house and home. And the solution? Simply predation and disease, which play the role that human beings might label "providence." As far as the written record reveals, no one recognized the self-elimination of a species as a potential problem for animals until the danger had become suspected among human beings. One of the earliest descriptions of this population problem for other animals was given by the Reverend Joseph Townsend, an English geologist. His key contribution was published in 1786, twelve years before Malthus's celebrated essay (Box 25-1). Townsend was dependent upon others for the outline of his story, and there is some question as to whether the details are historically correct. But the thrust of the story must be true: a single species (goats, in this case) exploiting a resource (plants) cannot, by itself, maintain a stable equilibrium at a comfortable level of living. The animals will either die after eating up all the food, or their numbers will fluctuate painfully. (Details differ, depending on the species and the environment.) Stability and prosperity require that the gift of exponential growth be opposed by some sort of countervailing force (predatory dogs, in Townsend's example). However deplorable predators may be for individuals who happen to be captured and eaten, for the prey population as a whole predators are (over time) a blessing. With millions of different species of animals there are many different particular explanations of how they manage to persist for thousands or millions of years. The species we are most interested in is, of course, Homo sapiens. A meditation on Townsend's account led to a challenging set of questions. "If all this great earth be no more than the Island of Juan Fernandes, and if we are the goats, how can we live "the good life" without a functional equivalent of the dogs? Must we create and sustain our own dogs? Can we do so, consciously? And if we can, what manner of beast will they be?"
Introduction: Apprehending Climate Change
Authors: Fleming James R.
Published: November 2020

Apprehensions have been multiplying rapidly that we are approaching a crisis in our relationship with nature, one that could have potentially catastrophic results for the sustainability of civilization and even the habitability of the planet. Much of the concern is rightfully focused on changes in the atmosphere caused by human activities. Only a century after the discovery of the stratosphere, only five decades after the invention of chlorofluorocarbons (CFCs), and only two decades after atmospheric chemists warned of the destructive nature of chlorine and other compounds, we fear that ozone in the stratosphere is being damaged by human activity. Only a century after the first models of the carbon cycle were developed, only three decades after regular CO2 measurements began at Mauna Loa Observatory, and only two decades after climate modelers first doubled the CO2 in a computerized atmosphere, we fear that the Earth may experience a sudden and possibly catastrophic warming caused by industrial pollution. These and other environmental problems were brought to our attention mainly by scientists and engineers, but the problems belong to us all. Recently, policy-oriented social scientists, public officials, and diplomats have turned their attention to the complex human dimensions of these issues. New interdisciplinary and multidisciplinary collaborations have arisen between scientists and policymakers to examine the extremely challenging issues raised by global change. There has been a rising tide of literature—scholarly works, new journals, textbooks, government documents, treaties, popular accounts—some quite innovative, others derivative and somewhat repetitious. This has resulted in growing public awareness of environmental issues, new understanding of global change science and policy, widespread concerns over environmental risks, and recently formulated plans to intervene in the global environment through various forms of social and behavioral engineering, and possibly geoengineering. Global change is now at the center of an international agenda to understand, predict, protect, and possibly control the global environment. The changing nature of global change—the historical dimension—has not received adequate attention. Most writing addresses current issues in either science or policy; much of it draws on a few authoritative scientific statements such as those by the Intergovernmental Panel on Climate Change (IPCC); almost none of it is informed by historical sensibility.
Climate and Culture in Enlightenment Thought
Authors: Fleming James R.
Published: November 2020

The debate over climate change, both from natural causes and human activity, is not new. Although the Baron C.-L. de Montesquieu is undoubtedly the best known Enlightenment thinker on the topic of climatic determinism, others, notably the Abbé Du Bos, David Hume, and Thomas Jefferson, observed that climatic changes exerted a direct influence on individuals and society and that human agency was directly involved in changing the climate. Climate—from the Greek term klima, meaning slope or inclination—was originally thought to depend only on the height of the Sun above the horizon, a function of the latitude. A second tradition, traceable to Aristotle, linked the quality of the air (and thus the climate) to the vapors and exhalations of a country. The Hippocratic tradition further linked climate to health and national character. As late as 1779, the Encyclopdédie of Denis Diderot and Jean le Rond D’Alembert defined “climat” geographically, as a “portion or zone of the surface of the Earth, enclosed within two circles parallel to the equator,” in which the longest day of the year differs in length on its northern and southern boundaries by some quantity of time, for example one-half hour. The article goes on to mention Montesquieu’s position on “l’influence du climat sur les mœurs, le charactère, et les loix des peuples.” The second definition of climate provided by the Encyclopdédie was medical, identified primarily as the temperature of a region and explicated through its effects on the health and well-being of the inhabitants. The idea that climate influenced culture was derived in part from the writings of ancient and medieval philosophers, geographers, and historians, including the works of Hippocrates, Albertus Magnus, and Jean Bodin. With no established science of climatology, Enlightenment thinkers apprehended climate and its changes primarily in a literary way. They compared the ancient writings to recent weather conditions, linked the rise and fall of creative historical eras to changes in climate, and promoted a brand of climatic determinism based on geographic location and the quality of the air.
Privileged Positions: The Expansion of Observing Systems
Authors: Fleming James R.
Published: November 2020

Earlier, I posed the question of how privileged perspectives are established on the ubiquitous and changeable climate. Enlightenment philosophes based their arguments on the impressions of travelers and colonists. Their perspectives were framed by memory, history, and folklore; their reasoning colored by environmental determinism. Early American writers followed this pattern, adding patriotic hopes to the rhetorical mix. A new approach to the climate issue was developing, however, based on projects that set out to collect large amounts of meteorological data. Thomas Jefferson, who participated vigorously in the great climate debate, was a staunch advocate of widespread, comparative, and long-term meteorological measurements. Inspired by Benjamin Franklin’s suggestion that extensive measurements of the climate would be necessary to resolve the issue, Jefferson advised his correspondents to keep weather diaries and send them to the American Philosophical Society. Throughout his life, Jefferson maintained the belief that human-induced climate change due to settlement would be proved by extensive measurements. He wrote the following to Lewis Beck in 1824: “We want . . . [an index of climate] for all the States, and the work should be repeated once or twice in a century, to show the effect of clearing and culture towards the changes of climate.” In the closing decades of the eighteenth century in Europe, and slightly later in Russia and the United States, serious attempts were made to broaden the geographic coverage of observations, standardize their collection, and publish the results. Individual observers in particular locales dutifully tended to their journals, and networks of cooperative observers gradually extended the meteorological frontiers. Much of the work was state funded and motivated primarily by desires to improve agriculture, answer health-related questions, and provide public storm warnings. Military issues and national pride were also at stake. Most of the projects were motivated, at least in part, by the hope that climatic patterns and their temporal changes would be revealed directly. The development of sytematic data collection networks occurred over several centuries. Its history can be traced to many roots, some more significant than others. Descriptive records of phenomena related to the climate, such as the opening and closing of rivers, the first and last frosts, and the blossoming and harvesting of fruit trees, existed from early times.
Introduction to Lipids
Authors: Hanahan Donald J.
Published: November 2020

Concomitant with the explosive development and progress made in the field of molecular biology, initiated by development and proof of the double helix structure of DNA some 40 years ago, there has been a much more subdued, but equally exciting and important, development in the area of signal transduction (Nishizuka, 1992; Berridge, 1984; Exton, 1990). What makes the latter subject so enchanting to biochemists is the finding that membrane phospholipids are intimately involved in the transduction process. Interestingly, the potential role of phospholipids in the signal transduction pathway was formulated some 40 years ago also. (Perhaps all great discoveries occur in 40 year cycles.) In any event the first hint of any possible involvement of phospholipids in cellular stimulus responses was gained from the work of Hokin and Hokin, which first appeared in 1953. In this classic paper, these investigators reported that treatment of pigeon pancreas slices with acetylcholine or carbamylcholine (cholinergic drugs) resulted not only in the secretion of amylases but also in the turnover of two specific membrane phospholipids, namely, phosphatidylinositol and phosphatidic acid. While the entire process of stimulus response in a mammalian cell is now much more complicated, nevertheless the findings by Hokin and Hokin were of major importance in the maturation of this field. Unfortunately, the impact of the Hokins’ observations was not immmediately felt. At that point in time, phospholipids were viewed mainly as semipermeable membrane structures whose main function was to regulate the ion content of the cell. In addition, another deterrent was the limited information on the chemical structure of the mammalian cell phospholipids. Hence there was a hiatus of many years in which low-profile lipid chemists and biochemists labored to solve the chemical nature of membrane lipids and to deduce their physical arrangement in the cell. Then in 1975, Michell published a key paper (Michell, 1975) in which he noted the importance of the inositol-containing phospholipids in the membrane process known as calcium gating. This paper initiated what can be called the “PI” era, which is still very much alive and well today.
Minor Phospholipids: Platelet activating factor (PAF) and PAF analogs, Lysophosphatidic acid and phosphatidic acid, Phosphatidylglycerol, Cardiolipin, Sphingosine-1-P
Authors: Hanahan Donald J.
Published: November 2020

In the previous chapters, the emphasis was placed on establishing the chemical nature of phospholipids normally found in relatively high concentrations in mammalian cells. The methodology described for identification of these compounds can be applied, perhaps with some minor modifications to the structural characterization of phospholipids found in plants, fish, and bacteria. Interwoven into the fabric of these chapters was the subtle reference to their potential biological role in cellular behavior. As lipid biochemistry has developed over the past several years, there is no doubt that the field of signal transduction has had an enormous impact on phospholipid awareness. As might be expected, the potential for phospholipids or their metabolites to exhibit biological activity loomed large. As will be evident in this chapter, phospholipids can certainly have biological activity and this theme shall be explored in some depth. The title “Minor Phospholipids” is not meant to be belittling, but is only intended to reflect the fact that these phospholipids are present in very low concentrations. In fact, some are considered to be formed only after a cell has been stimulated by an extracellular agonist. As shall be seen, these compounds have considerable biological activity and hence are really of major importance in the cellular metabolic scene. The term platelet activating factor (PAF) was originally applied to a phosphoglyceride capable of activating platelets, leading to their aggregation. In addition, in certain species, there was also discharge of their dense granules (as indicated by serotonin release from the platelets). This nomenclature was unfortunate because it is now well established that many cells can produce this compound and that, likewise, PAF can stimulate many other cells. There are many other compounds, such as thrombin and arachidonic acid, which also can activate platelets. Notwithstanding this problem of nomenclature, there is a widespread (deeply entrenched) usage of this term to indicate a specific type of phospholipid with a particular biological activity. Given the status of this field at the current time, the use of the term PAF will be continued here.
Four-Body Algebraic Theory
Authors: Iachello F. , Levine R. D.
Published: November 2020

In tetratomic molecules, there are three independent vector coordinates, rl, r2, and r3, which we can think of as three bonds. The general algebraic theory tells us that a quantization of these coordinates (and associated momenta) leads to the algebra . . .G = U1(4) ⊗ U2(4) ⊗ U3(4). . . . . . .(5.1). . . As in the previous case of two bonds, discussed in Chapter 4, we introduce boson operators for each bond . . .σ †1, π†1μ , μ = 0, ±1 ,. . . . . .σ †2, π†2μ , μ = 0, ±1 ,. . . . . .σ †3, π†3μ , μ = 0, ±1 ,. . . . . .(5.2). . . together with the corresponding annihilation operators σ1, π1μ, σ2, π2μ, σ3, π3μ. The elements of the algebras Ui(4) are the same as in Table 2.1, except that a bond index i = 1, 2, 3 is attached to them.
Double Generativity and Complete Effective
Authors: Smullyan Raymond M
Published: November 2020

§1. Complete Effective Inseparability. A disjoint pair (A1,A2) is by definition recursively inseparable if no recursive superset of A1 is disjoint from A2. This is equivalent to saying that for any disjoint r.e. supersets ωi and ωj of A1 and A2, the set ωi is not the complement of ωj —in other words, there is a number n outside both ωi and ωj. The disjoint pair (A1,A2) is called effectively inseparable—abbreviated E.I.—if there is a recursive function δ(x, y)—called an E.I. function for (A1, A2)—such that for any numbers i and j such that A1⊆ ωi and A2Í ωj. with ωi being disjoint from ωj, the number d(i , j) is outside both a;,- and ωj. We shall call a disjoint pair (A1, A2) completely E.I. if there is a recursive function δ(x, y)—which we call a complete E.I. function for (A1, A2)—such that for any numbers i and j, if A1⊆ ωi and A2Í ωj, then δ(i , j) Í ωi ↔ d(i , j)Í ωj (in other words, d(i, j) is either inside or outside both sets ωi and ωj.). [If ωi and ωj happen to be disjoint, then, of course, d(i, j) is outside both ωi and ωj, so any complete E.I. function for (A1,A2) is also an E.I. function for (A1,A2) In a later chapter, we will prove the non-trivial fact that if (A1, A2) is E.I. and A1 and A2 are both r.e., then (A1,A2) is completely E.I. [The proof of this uses the result known as the double recursion theorem, which we will study in Chapter 9.] Effective inseparability has been well studied in the literature. Complete effective inseparability will play a more prominent role in this volume—especially in the next few chapters. Proposition 1. (1) If (A1,A2) is completely E.I., then so is (A2,A1) —in fact, if d(x,y) is a complete E.I. function for (A1,A2), then d(y,x) is a complete E.I. function for (A2, A1).
Recursion Theorems
Authors: Smullyan Raymond M
Published: November 2020

We have proved that the complement of every completely productive set (in other words, every generative set) is universal, and this was enough to establish Theorem A of Chapter 6. In Chapter 10 we will prove Myhill’s stronger result that the complement of every productive set is universal. For this proof, we will need the recursion theorem of this chapter. Recursion theorems (which can be stated in many forms) have profound applications in recursive function theory and metamathematics, and we shall devote considerable space to their study. To illustrate their rather startling nature, consider the following mathematical “believe-it-or-not’s”: Which of the following propositions, if true, would surprise you? . . . 1. There is a number n such that ωn = ωn+1.
Three Special Topics
Authors: Smullyan Raymond M
Published: November 2020

The topics of this chapter are of more specialized interest and are not necessary for the results of our final chapter. They will probably be of more interest to the specialist (particularly the results of Section III) than to the general reader. We know from Chapter 2 that if all recursive sets are representable in S, then S is undecidable. We also know from Chapter 4 that if all recursively enumerable sets are representable in S, then S is not only undecidable but generative. We might also ask the question, If all recursive sets are representable in S, is S necessarily generative? Shoenfield [1961] answered this question negatively. He constructed an axiomatizable system in which all recursive sets are representable, and so the system is undecidable, but he showed that the system is not creative. Let us say that all recursive sets are uniformly representable in S if there is a recursive function g(x) such that for any number i, if ωi is a recursive set, then g(i) is the Godel number of a formula which represents ωi in S. We will show that if all recursive sets are uniformly representable in S, then S is generative. We also showed in Chapter 2 that if all recursive sets are definable in S and S is consistent, then the pair (P,R) of its nuclei is recursively inseparable. Under the same hypothesis, is the pair (P,R) necessarily effectively inseparable? The answer is no. In Shoenfield’s system all recursive sets are not only representable, but definable. However, the set P is not creative. Hence the pair (P, R) of nuclei of the system, though recursively inseparable, is not effectively inseparable.
Thermoelasticity
Authors: Erman Burak , Mark James E.
Published: November 2020

The important postulate that intermolecular interactions are independent of extent of deformation leads directly to the conclusion that such interactions cannot contribute to an energy of elastic deformation ΔEel at constant volume. In the earliest theories of rubberlike elasticity, it was additionally assumed that, intramolecular contributions to ΔEel were likewise nil. In this idealization that the total ΔEel is zero, the elastic retractive force exhibited by a deformed polymer network would be entirely entropic in origin. At the molecular level, this would correspond, of course, to assuming all configurations of a network chain to be of exactly the same conformational energy and thus the average configuration to be independent of temperature. Under these circumstances, the dependence of stress on temperature is strikingly simple, as shown, for example, by the equation . . . f* = υkT/V (〈r2〉i/〈r2〉0)(α – α-2) . . . . . . (9.1) . . . that characterizes a polymer network in elongation where, it should be recalled, 〈r2〉i3/2 is proportional to the volume of the network. This additional assumption that 〈r2〉0 is independent of temperature would lead to the prediction that the elastic stress determined at constant volume and elongation α is directly proportional to the absolute temperature. Such network chains would be akin to the particles of an ideal gas, which would obey the equation of state p = nRT(1/V) and thus exhibit a pressure at constant deformation (1/V) likewise directly proportional to the temperature.
Small-Angle Neutron Scattering
Authors: Erman Burak , Mark James E.
Published: November 2020

Small-angle neutron scattering (SANS) experiments from networks were initiated by Benoit and collaborators in the mid-1970s. Currently, SANS is an important major technique used in studying network structure and behavior. Its importance lies in its being a direct method with which observations may be made at the molecular-length scale without the need for a theoretical model for interpreting the data. This feature makes neutron scattering a valuable tool for testing various molecular theories on which current understanding of elastomeric networks is based. The general features of the technique are explained in section 14.1, followed in section 14.2 by a review of relevant experimental work. Section 14.3 then describes different theories of neutron scattering from networks, and compares them with experimental results. The technique of neutron scattering and its application to polymers in the dilute and bulk states, to blends, and to networks are described in several review articles and a book. The reader is referred to this literature for a more comprehensive understanding of the technique and the underlying theory. The neutrons incident on a sample during a typical experiment are from a nuclear reactor. Neutrons leaving the source are first collimated so that they arrive at the sample in the form of plane waves. Figure 14.1 shows such an incident neutron wave on two scattering centers i and j. After interacting with the scattering centers, the neutrons move in various directions. In a neutron scattering experiment, the intensity of the scattered neutron wave is measured as a function of the angle θ shown in the figure, in which the vectors k0 and k are the wave propagation vectors for incident and scattered neutron rays, respectively. In general, the magnitudes of k0 and k differ if there is energy change upon scattering, and in this case the scattering is called inelastic. Inelastic scattering experiments are particularly useful in studying the dynamics of a system, such as relaxation or diffusion.
The Use of Behavioral Ecotypes in the Study of Evolutionary Processes
Authors: Riechert Susan E.
Published: November 2020

Ecotypic variation refers to differences in traits between populations that reflect adaptation to different selection pressures. The origin of the term lies in Turesson’s (1922) observation that population differences in plant growth forms often breed true in a controlled environment. From experiments, Turesson (1922) concluded that much between-population variation in phenotypic traits reflects genotypic adaptation to local conditions. He described the phenomenon as ecotypic variation and the species population exhibiting a particular variant as an ecotype. The meaning of adaptation must be examined if the phenomenon of ecotypic variation is to be understood. Readers should refer to Reeve and Sherman (1993) for an in-depth analysis of the problems surrounding various definitions of this term. Briefly, Antonovics (1987) divided evolutionary studies into two distinct classes: those that consider the influences of past events (phylogenies) and those that consider why certain traits predominate over others in an ongoing selection process. Tinbergen (1963) proposed a similar subdivision. Most definitions of adaptation incorporate these two elements in that they require a history of selective modification of a trait. For instance, Harvey and Pagel (1991) express adaptations in terms of traits derived in their phylogenetic group that have current utilitarian function. However, ecotypic variation refers to trait differences that reflect adaptations to local conditions at one point in time. Phylogenetic constraints need not be examined except in terms of how they might limit adaptation. Therefore, when I refer to adaptation in this chapter, I will be limiting it to “a phenotypic variant that results in the highest fitness among a specified set of variants in a given environment” (Reeve and Sherman 1993). This definition is history-free. It is based on extant competing phenotypes, and thus fitness is of significance only in reference to current alternatives. Although the definition I borrow from Reeve and Sherman (1993) for adaptation does not specify that there be an underlying genetic mechanism, optimization models assume that there is (Charlesworth 1977). Minimally, we wish to know whether sufficient genetic complexity (variability) exists for a predicted optimal solution to be reached.