bluuebunny/crossref_metadata_2025 huggingface dataset:
Flow Over Hills
Authors: Kaimal J. C. , Finnigan J. J.
Published: November 2020

We now move on to the next obstacle to understanding how the boundary layer behaves in general through the study of flow over ridges and hills. In Chapter 4 we examined simple changes in surface conditions and showed how their effects extend upwards with increasing downwind distance. The distinguishing features of the flow over those changes were a small perturbation in the pressure field and an internal boundary layer, the depth of which was controlled by turbulent diffusion from the new surface. Here, we confront not a change in surface properties but a change in surface elevation that forces large-scale changes in the pressure field. The response to this forcing is more complicated than any we have tackled so far, but the work of many scientists over the past 25 years gives us a measure of understanding of the processes involved. In addition to extending to hillsides the kind of analyses of wind and turbulence we have already presented, there are new questions that only arise in the context of hill flows. One, with ramifications for large-scale prediction of the weather and climate, is how much drag hills exert on the atmosphere flowing over them. For large hills and mountains this problem is dominated by the behavior of the internal gravity waves initiated by hills; over lower topography, however, it involves a subtle balance between changes in the surface stress distribution and the pressure field. In questions of wind turbine siting, understanding the position and magnitude of accelerations in the mean wind becomes crucial, whereas changes to both the mean wind and turbulence are important when predicting the fate of atmospheric pollutants in hilly terrain or estimating wind loads on buildings. The pattern of airflow around a hill is determined not only by the hill shape but also by its size. A characteristic feature of the atmosphere as a whole is its static stability, extending all the way to the ground at night-time and down to zi during the day. As a result, the vertical movement of air parcels that must occur as the wind flows over a hill is accompanied by a gravitational restoring force.
Becoming a Physician
Authors: Bonner Thomas Neville
Published: November 2020

Written by eminent education scholar Thomas Neville Bonner, Becoming A Physician is a groundbreaking, comprehensive history of Western medical education. The only work of its kind, it covers the United States, Great Britain, France, and Germany. Comparative in focus, the narrative unfolds within the context of social, political, and intellectual transformations that occurred in Europe and North America between the Enlightenment and Nazi Germany. Viewing the late eighteenth century as a watershed in the development of medical education, Bonner begins by describing how earlier practices evolved in the 1800s with the introduction of clinical practices. He then traces the growth of laboratory teaching in the nineteenth century and the twentieth-century preoccupation with establishing a university standard of medical education. Throughout, Bonner pays particular attention to the students, chronicling their daily lives and discussing changes in the medical school population and the various biases-- class, gender, racial, and religious--students and prospective students faced.
Introduction
Authors: Marvin Carolyn
Published: November 2020

New technologies is a historically relative term. We are not the first generation to wonder at the rapid and extraordinary shifts in the dimension of the world and the human relationships it contains as a result of new forms of communication, or to be surprised by the changes those shifts occasion in the regular pattern of our lives. If our own experience is unique in detail, its structure is characteristically modern. It starts with the invention of the telegraph, the first of the electrical communications machines, as significant a break with the past as printing before it. In a historical sense, the computer is no more than an instantaneous telegraph with a prodigious memory, and all the communications inventions in between have simply been elaborations on the telegraph’s original work. In the long transformation that begins with the first application of electricity to communication, the last quarter of the nineteenth century has a special importance for students of modern media history. Five proto-mass media of the twentieth century were invented during this period: the telephone, phonograph, electric light, wireless, and cinema. This period is not the usual starting point for the social history of Anglo-American electric media, which is generally assumed to begin only with the institutional birth of film and broadcasting and the development of large audiences in the twentieth century. The present study modestly attempts to push back those beginnings to the late nineteenth century, when Anglo-American culture was fascinated by the communicative possibilities of the telegraph, the telephone, and the incandescent lamp—choices that may come as a surprise to contemporary sensibilities focused on twentieth-century mass media. For media historians, the phenomenon of twentieth-century electronic mass media lies like a great whale across the terrain of our intellectual concern. Asked to explain what sort of phenomenon it is, most of us will unhesitatingly point to the hundreds of millions of radio and television sets that are bought by consumers and promoted by vast industries. This artifactual notion is pervasive and not much debated, for it seems simple, obvious, and convenient.
Community and Class Order Progress Close to Home
Authors: Marvin Carolyn
Published: November 2020

Much of the literature on electricity in the late nineteenth century can be read as the wishful template of a world that electrical professionals believed they would create, given the opportunity. The world that looked most comfortable to them was less the egalitarian one they professed to desire in their more serf-conscious public moments than one in which the stability of familiar social and class structures would be preserved, with the important exception that other people would come to recognize the wisdom of professional electricians’ values, and might even think, look, and act very much like electricians themselves. With the more general application of electricity throughout society, electricians believed, the world could change only to their advantage. For them, electricity was the transformative agent of social possibility. Through their power over it, it would be a creator of social miracles. Electricity had the vitality of a natural force; they had charge of its control and direction. Experts felt that society had yet to grant them the recognition appropriate to so weighty a social responsibility. They were also concerned about the possibility of this natural force’s getting out of control, particularly their control. Thus, at the same time that electrical professionals were confidently and proudly prophesying Utopian accomplishments through the proper exercise of electrical knowledge, especially at the most abstract levels of discussion about the future of civilization they were also conducting an anxious, less publicized discussion about the possible social catastrophes of electrical metamorphosis. A metamorphosis it surely was, though in the early stages. While electric lights and trolley cars constituted the most visible proof of change in the urban environment, electric telephones had also diffused with impressive rapidity. Early telephone figures are difficult to find and often unreliable. Our best evidence probably reflects only orders of magnitude. Phone figures for the late nineteenth century are rarely broken down into residential and business telephones, or by region, although these were key factors in telephone density and distribution. It is difficult to be sure, after the Bell patents expired in 1893 and the telephone business temporarily opened up to a number of small competitors, how accurate was the reporting of independent telephones.
Disequilibrium 2: Associated Equilibrium States
Authors: Bayly Brian
Published: November 2020

The purpose of this chapter is to consider the question: how much uncertainty, or how coarse an approximation, is involved when we use ideas borrowed from equilibrium thermodynamics and apply them in nonequilibrium situations? To be specific, consider eqn. (3.2): . . . μ1 – μ2 = VB(P1 – P2) . . . When we have in mind two equilibrium states, isolated from each other, one static at pressure P1 and the other static at pressure P2, the equation is a regular part of equilibrium thermodynamics and has a high degree of validity on that account. But when we have in mind a single nonequilibrium state, part of which is almost static at pressure close to P1, and part of which is almost static at pressure close to P2 (and part of which is not so close to static at all), is there really a contrast in chemical potential between one portion of the material and another portion of the same material farther along the system? And if so, can it really be estimated by using eqn. (3.2)? The answers, fortunately, are Yes and Yes. For an example where the nature of the approximation we make can be quite clearly seen, consider the long bar in Figure 4.1. The bar is uniform in composition except for one minor constituent R whose concentration diminishes linearly along the bar from left to right (and for purposes of this example we assume that the activity coefficient A is exactly 1 everywhere so that R's activity and its concentration are the same); the concentration is represented by the sloping line in Figure 4.1b. We arbitrarily select five small portions of the bar for consideration; for any single portion, an average concentration of R can be established, and we can imagine a material that is homogeneous, with that concentration of R at all points. In such a material, the chemical potential of R is perfectly well defined.
Body Modeling
Authors: Badler Norman I. , Phillips Cary B. , Webber Bonnie Lynn
Published: November 2020

In order to manipulate and animate a human figure with computer graphics, a suitable figure must be modeled. This entails constructing a satisfactory surface skin for the overall human body shape, defining a skeletal structure which admits proper joint motions, adding clothing to improve the verisimilitude of analyses (as well as providing an appropriate measure of modesty), sizing body dimensions according to some target individual or population, and providing visualization tools to show physically-relevant body attributes such as torque loads and strength. In computer graphics, the designer gets a wide choice of representations for the surfaces or volumes of objects. We will briefly review current geometric modeling schemes with an emphasis on their relevance to human figures. We classify geometric models into two broad categories: boundary schemes and volumetric schemes. In a boundary representation the surface of the object is approximated by or partitioned into (non-overlapping) 0-, 1-, or 2- dimensional primitives. We will examine in turn those representations relevant to human modeling: points and lines, polygons, and curved surface patches. In a volumetric representation the 3D volume of the object is decomposed into (possibly overlapping) primitive volumes. Under volumetric schemes we discuss voxels, constructive solid geometry, ellipsoids, cylinders, spheres, and potential functions. The simplest surface model is just a collection of 3D points or lines. Surfaces represented by points require a fairly dense distribution of points for accurate modeling. Clouds of points with depth shading were used until the early 1980’s for human models on vector graphics displays. They took advantage of the display’s speed and hierarchical transformations to produce the perceptual depth effect triggered by moving points [Joh76] (for example, [GM86]). A related technique to retain display speed while offering more shape information is to use parallel rings or strips of points. This technique is used in LifeForms™ [Lif91, Cal91]. Artistically positioned “sketch lines” were used in one of the earliest human figure models [Fet82] and subsequently in a Mick Jagger music video, “Hard Woman” from Digital Productions. Polygonal (polyhedral) models are one of the most commonly encountered representations in computer graphics.
Eye Tracking in Advanced Interface Design
Authors: Jacob Robert J. K.
Published: November 2020

The problem of human-computer interaction can be viewed as two powerful information processors (human and computer) attempting to communicate with each other via a narrow-bandwidth, highly constrained interface (Tufte, 1989). To address it, we seek faster, more natural, and more convenient means for users and computers to exchange information. The user’s side is constrained by the nature of human communication organs and abilities; the computer’s is constrained only by input/output devices and interaction techniques that we can invent. Current technology has been stronger in the computer-to-user direction than the user-to-computer, hence today’s user-computer dialogues are rather one-sided, with the bandwidth from the computer to the user far greater than that from user to computer. Using eye movements as a user-to-computer communication medium can help redress this imbalance. This chapter describes the relevant characteristics of the human eye, eye-tracking technology, how to design interaction techniques that incorporate eye movements into the user-computer dialogue in a convenient and natural way, and the relationship between eye-movement interfaces and virtual environments. As with other areas of research and design in human-computer interaction, it is helpful to build on the equipment and skills humans have acquired through evolution and experience and search for ways to apply them to communicating with a computer. Direct manipulation interfaces have enjoyed great success largely because they draw on analogies to existing human skills (pointing, grabbing, moving objects in space), rather than trained behaviors. Similarly, we try to make use of natural eye movements in designing interaction techniques for the eye. Because eye movements are so different from conventional computer inputs, our overall approach in designing interaction techniques is, wherever possible, to obtain information from a user’s natural eye movements while viewing the screen, rather than requiring the user to make specific trained eye movements to actuate the system. This requires careful attention to issues of human design, as will any successful work in virtual environments. The goal is for human-computer interaction to start with studies of the characteristics of human communication channels and skills and then develop devices, interaction techniques, and interfaces that communicate effectively to and from those channels.
Input Devices and Interaction Techniques for Advanced Computing
Authors: Scott Mackenzie I.
Published: November 2020

One enduring trait of computing systems is the presence of the human operator. At the human-computer interface, the nature of computing has witnessed dramatic transformations—from feeding punched cards into a reader to manipulating 3D virtual objects with an input glove. The technology at our fingertips today transcends by orders of magnitude that in the behemoth calculators of the 1940s. Yet technology must co-exist with the human interface of the day. Not surprisingly, themes on keeping pace with advances in technology in the human-computer interface and, hopefully, getting ahead, underlie many chapters in this book. The present chapter is no exception. Input devices and interaction techniques are the human operator’s baton. They set, constrain, and elicit a spectrum of actions and responses, and in a large way inject a personality on the entire human-machine system. In this chapter, we will present and explore the major issues in “input,” focusing on devices, their properties and parameters, and the possibilities for exploiting devices in advanced human-computer interfaces. To place input devices in perspective, we illustrate a classical human-factors interpretation of the human-machine interface (e.g., Chapanis, 1965, p. 20). Figure 11-1 simplifies the human and machine to three components each. The internal states of each interact in a closed-loop system through controls and displays (the machine interface) and motor-sensory behaviour (the human interface). The terms “input” and “output” are, by convention, with respect to the machine; so input devices are inputs to the machine controlled or manipulated by human “outputs.” Traditionally human outputs are our limbs—the hands, arms, legs, feet, or head—but speech and eye motions can also act as human output. Some other human output channels are breath and electrical body signals (important for disabled users). Interaction takes place at the interface (dashed line in Figure 11-1) through an output channel—displays stimulating human senses—and the input channel. In the present chapter, we are primarily interested in controls, or input devices; but, by necessity, the other components in Figure 11-1 will to some extent participate in our discussion.
High-Performance Implementation
Authors: Ashcroft E. A. , Faustini A. A. , Jaggannathan R. , Wadge W. W.
Published: November 2020

In Chapter 1, we saw how Lucid could be used to express solutions to standard problems such as sorting and matrix multiplication. One of the unique characteristics of Lucid is not only that it can be used as a programming language but it can also be used as a “composition” language. That is, instead of using Lucid to specify computations, it can be used to express how computation components (expressed in some other language) can be “glued” together to form a coherent application. By doing so, the resulting application can enjoy some of the practical benefits attributable to Lucid such as high performance through exploitation of implicit parallelism and robustness through software fault tolerance. In this chapter, we discuss one such use of Lucid—as part of a hybrid language to construct parallel applications to be executed on conventional parallel computers. A conventional parallel computer either consists of a number of processors each with local memory interconnected by a network (as in distributed memory architectures) or a number of processors that share memory possibly using an interconnection network (as in shared memory architectures). The past decade has seen the advent of conventional parallel computers starting with the Denelcor HEP evolving to the CM-2 and Intel Hypercube and further evolving to the CM-5, Intel Paragon, Cray T3D, and IBM SP-2. Even networks of workstations (or workstation clusters) are seen as low-cost (“poor man’s”) parallel computers. Programming of conventional parallel computers has proven to be far more challenging than had been expected. Part of the reason is the continued use of low-level, explicitly parallel programming models such as PVM [42], Linda [10]. Two factors have fueled the continuing use of such languages despite their limited success. 1. The need to reuse existing sequential code because the cost of rewriting legacy applications from scratch is considered prohibitive both in economic and technical terms. 2. The need to run on conventional parallel computers that view a “parallel program” at a low level—as consisting of sequential processes that frequently synchronize and communicate with each other using some form of message passing.
Conservation of Energy
Authors: Furbish David Jon
Published: November 2020

We briefly considered in Chapter 6 a geologically important class of flows—buoyancy driven flows—in which thermal effects hold an essential part in creating the forces that induce flow. We also should recall that fluid properties such as viscosity can vary with temperature. As fluids are heat-conducting media, taking into account the thermal energy conditions and heat flow within a fluid therefore is often an essential part of describing a flow field. Thermal energy, however, is not transported merely by conduction; in a moving fluid, thermal energy also is advected from position to position. In addition, recall that the thermal energy of a fluid, according to the first law of thermodynamics, is inextricably coupled with energy in the form of work performed between a fluid element and its surroundings. It is therefore important to consider the mechanical energy of a fluid when describing its thermal conditions. To this end, the developments below concern conservation of energy in both thermal and mechanical forms. Analogous to our treatment of conservation of mass, we will derive equations that describe a condition—conservation of energy—which must be satisfied at each coordinate position in a fluid. An important outcome of our development of expressions for conservation of energy is a set of dynamical equations for the special case of an ideal fluid. In component form, these are referred to as Euler’s equations, and arise from conservation of purely mechanical energy, neglecting thermal forms. (We will derive Euler’s equations again in Chapter 10 using an explicit treatment of the forces involved in fluid motion.) Conservation of energy also applies to flow in porous media; the relevant expressions are similar to those for purely fluid flow, but with several important differences that arise from the two-phase character (solid and fluid) of flow in porous media. In relation to this topic, we also will develop the idea of Hubbert’s potential, and the relation of this potential to piezometric head. This is a cornerstone of the theory of flow in porous media. Our objective is to illustrate how Hubbert’s potential, and head, are obtained from applying the idea of conservation of mechanical energy to a fluid.
Whose Children Are We Talking About?
Authors: Siegler Robert S.
Published: November 2020

My children have never looked much like those described in most theories of cognitive development. I don’t mean that they are generally deviant or that they perform abnormally on conservation or class inclusion tasks. They generally seem more or less normal, and on the few occasions when I have presented tasks from the cognitive developmental literature, they have acted pretty much like the children described in the articles. Where my children are altogether different from the theoretical descriptions is in the variability of their thinking. Cognitive developmental theories generally depict age and thought as proceeding in a 1:1 relation. At an early age, children think in one way; at a later age, they think in another way; at a still later age, they think in a third way. Such descriptions are so pervasive that they begin to feel like reality. Young children are said to form thematic concepts; somewhat older ones to form chain concepts; yet older ones to form true concepts. The reasoning of young children is said to be preoperational; that of somewhat older ones concrete operational; that of yet older ones formal operational. Young children are said to have one theory of mind; somewhat older ones a different, more inclusive theory; yet older ones a more advanced theory still. The story is the same with characterizations of performance on specific tasks. In descriptions of the development of the concept of living things, 3- and 4-yearolds are said to think that anything that moves is alive, 5- to 8-year-olds that animals—and only animals—are alive, and older children that plants as well as animals are alive. In descriptions of the development of addition skill, kindergartners are said to count from one; first through third graders to count from the larger addend; fourth graders and older children to retrieve answers from memory. In descriptions of the development of serial recall strategies, 5-year-olds are said not to rehearse; 8-year-olds to rehearse in a simple way; 11-year-olds to rehearse in a more elaborate way. My children’s thinking has never looked as neat and clean as these 1:1 characterizations of the relation between age and thought.
Joseph Fourier’s Theory of Terrestrial Temperatures
Authors: Fleming James R.
Published: November 2020

The concept of the greenhouse effect has yet to receive adequate historical attention. Although most writing ahout the subject is concerned with current scientific or policy issues, a small but growing fraction of the literature contains at least some historical material, which, as this chapter shows for the case of Joseph Fourier, is largely unreliable. Jean Baptiste Joseph Fourier is best known today for his Fourier series, a widely used mathematical technique in which complex functions can be represented by a series of sines and cosines. He is known among physicists and historians of physics for his book Théorie analytique de la chaleur (1822), an elegant but not very precise work that Lord Kelvin described as “a great mathematical poem.” Most of his contemporaries knew him as an administrator, Egyptologist, and scientist. Fourier’s fortunes rose and fell with the political tides. He was a mathematics teacher, a secret policeman, a political prisoner (twice), governor of Egypt, prefect of Isère and Rhône, friend of Napoleon, baron, outcast, and perpetual member and secretary of the French Academy of Sciences. Most people writing on the history of the greenhouse effect merely cite in passing Fourier’s descriptive memoir of 1827 as the “first” to compare the heating of the Earth’s atmosphere to the action of glass in a greenhouse. There is usually no evidence that they have read Fourier’s original papers or manuscripts (in French) or have searched beyond the obvious secondary sources. Nor are most authors aware that Fourier’s paper, usually cited as 1827, was actually read to the Académie Royale des Sciences in 1824, published that same year in the Annales de Chimie et de Physique, and translated into English in the American Journal of Science in 1837! No one cites Fourier’s earlier references to greenhouses in his magnum opus of 1822 and in his earlier papers. Nor do they identify the subject of terrestrial temperatures as a key motivating factor in all of Fourier’s theoretical and experimental work on heat. Moreover, existing accounts assume far too much continuity in scientific understanding of the greenhouse effect from Fourier to today.
The Climatic Determinism of Ellsworth Huntington
Authors: Fleming James R.
Published: November 2020

The climate work of the unrestrained and undisciplined geographic determinist, eugenicist, and popular writer Ellsworth Huntington (1876–1947) can be categorized into three large themes: the influence of weather and weather changes on workers and students, the influence of climate on world civilizations, and the influence of solar variations on climate change. The first represented a sort of meteorological Taylorism, the second a reprise of enlightenment determinism, and the third a simplistic and wholly unrealistic pseudoscientific theory. Why, then, should we bother with him? One answer was provided by the historian Arnold Toynbee, who was “enormously influenced” by Huntington’s ideas about the relation between human beings and their physical environments. It was Toynbee’s opinion that “[s]tudents of human affairs may agree or disagree with Huntington, but in either case they will be influenced by him, so it is better that they should be aware of him.” Although Huntington’s thought was indeed influential in its time, since then his racial bias and crude determinisms have been largely rejected. Nonetheless, his categorical errors seem destined to be repeated by those who make overly dramatic claims for weather and climatic influences. Ellsworth Huntington was born in Galesburg, Illinois, on September 16, 1876, the third child and eldest son of Henry Strong Huntington, a Congregationalist minister, and Mary Lawrence Herbert. The Huntingtons were proud of their Puritan ancestry, which they traced to 1633. Following the call of the ministry, the family moved to Gorham, Maine, in 1877 and then in 1889 to Milton, Massachusetts, a wealthy suburb of Boston. Ellsworth attended the public high school, where he excelled in athletics and academics. His biographers have called him reclusive, but his brother suggested that perhaps he was humble rather than shy. Huntington passed the Harvard entrance examinations, but family finances precluded his enrollment there. Instead, he attended Beloit College, where he boarded with a maternal aunt, from 1893 to 1897. Following in the footsteps of T. C. Chamberlin (Beloit 1866), Huntington studied both classics and geology, publishing his first article, on local road-making materials, in the Transactions of the Wisconsin Academy of Sciences.
1987
Authors: Schorske Carl E.
Published: November 2020

My first encounter with the world of learning took place, if family account is to be believed, when I entered kindergarten in Scarsdale, New York. To break the ice among the little strangers, my teacher, Miss Howl, asked her pupils to volunteer a song. I gladly offered a German one, called “Morgenrot.” It was a rather gloomy number that I had learned at home, about a soldier fatalistically contemplating his death in battle at dawn. The year was 1919, and America’s hatred of the Hun still ran strong. Miss Howl was outraged at my performance. She took what she called her “little enemy” by the hand and marched him off to the principal’s office. That wise administrator resolved in my interest the problems of politics and the academy. She promoted me at once to the first grade under Mrs. Beyer, a fine teacher who expected me to work but not to sing. Was this episode a portent of my life in the halls of learning? Hardly. But it was my unwitting introduction to the interaction of culture and politics, my later field of scholarly interest. When I taught European intellectual history at Berkeley in the early 1960s,I devoted a portion of my course to the way in which the same cultural materials were put to different uses in different national societies. One day, I gave a lecture on William Morris and Richard Wagner. The intellectual journeys of these two quite dissimilar artist-thinkers involved stops at many of the same cultural stations. Morris began by using Arthurian legend to champion a religion of beauty, then became an enthusiast for Norse mythology and folk art, and ended a socialist. Wagner traversed much the same itinerary as Morris, but in the reverse direction, starting as a social radical, then reworking Nordic sagas, and ending, with the Arthurian hero Parsifal, in a pseudoreligion of art. In the midst of delivering my lecture, I suddenly saw before me a picture from my childhood that I thought to be by Morris.
Correlation Of Geomagnetic Activity With The Solar Wind
Authors: Kennel Charles F.
Published: November 2020

Even if a steady convection state could exist in principle, the magnetosphere will be rarely in it, since the interplanetary magnetic field is hardly ever stationary over the 2-4 hour convection cycle (Rostoker et al., 1988). Indeed, the hourly average north-south component of the interplanetary field retained the same sign for two consecutive hours only 12.2% of the time during solar cycles 20 and 21 (Hapgood et al., 1991). If only for this reason, we cannot avoid dealing with time-dependent convection. In this section, we take up one method of coping with the issue. Correlation studies take advantage of solar wind variability without ever needing to consider the precise nature of the time-dependent response of the magnetosphere. Though laborious, they are a procedurally straightforward way to test the viscous and reconnection models of convection. Geomagnetic activity, the response of geomagnetic field to currents flowing in the ionosphere and in space, has been monitored in an increasingly systematic way since the beginning of the eighteenth century. Today, a worldwide network of ground stations provides continuous records of the magnetic field at many different locations on the earth’s surface. Before computational data displays enabled large quantities of data to be summarized at a glance, the complex multi-station records were combined into single parameters called geomagnetic indices, which were designed to characterize one aspect or another of geomagnetic activity on a global scale. We will refer frequently to the auroral electrojet (AE) index, which was designed by Davis and Sugiura (1966) as a measure of electrojet activity in the auroral zone. The index is derived from the horizontal, northern component of the geomagnetic perturbation field measured at a number of observatories in the northern hemisphere. The number of observing stations contributing to the index is occasionally indicated in parentheses as AE(12) or AE(32), and so on. The maximum and minimum perturbations recorded at any given time at the stations in the AE network are called the AU and AL indices, respectively, for “upper” and “lower.” These provide a measure of the westward and eastward electrojet strengths. The difference between AU and AL is the AE index.
Drug Transport by Fluid Motion
Authors: Saltzman W. Mark
Published: November 2020

The rate of molecular movement by diffusion decreases dramatically with distance, and is generally inadequate for transport over distances greater than 100 μm. The movement of molecules over distances greater than 100 μm occurs in specialized compartments in the body: blood circulates through arteries and veins; interstitial fluid collects in lymphatic vessels before returning to the blood; cerebrospinal fluid (CSF) percolates through the central nervous system (CNS) in the brain ventricles and subarachnoid space. In these systems, molecules move primarily by bulk flow, or convection. Diffusive transport is driven by differences in concentration; convective transport is driven by differences in hydrostatic and osmotic pressure. This chapter introduces the principles of drug distribution by pressure-driven transport. The elaborate network of arteries, capillaries, and veins that carry blood throughout the body are described first in this chapter. Hydrostatic pressure within the blood vasculature drives fluid through the vessel wall (recall Equation 5-28) and into the extravascular space of tissues. Fluid flow through the interstitial space is not well understood, although the importance of interstitial flows in moving drug molecules through tissue is beginning to be appreciated. Engineering approaches for analyzing fluid flows in the interstitium are described in the second section of the chapter. Finally, the specialized systems for returning interstitial fluid to the blood are essential for clearance of molecules from the interstitial space; therefore, the chapter also provides a description of the dynamics of lymph flow in the periphery and CSF production and circulation in the brain. Our bodies appear, from the outside, to be solid masses that are slow to change, but, just beneath the surface, is a torrent of fluid motion. Blood moves at high velocity throughout the body within an interconnected and highly branched network of vessels. The cross-sectional area changes significantly along the network, and blood flow to the periphery emerges from the heart within a single vessel, which branches and rebranches to distribute blood to every tissue and organ.
Introduction
Authors: Greenlaw Raymond , Hoover H. James , Ruzzo Walter L.
Published: November 2020

The subject of this book is best illustrated by the following scenario. Suppose that you are employed in the halls of industry. More than a decade ago your company entered the highly competitive "bandersnatch" market. While other companies thought that bandersnatch design was an intractable problem, and spent millions on supercomputers to search for possible designs, your company had the foresight to employ a few theoretical computer scientists. They discovered that there was a feasible algorithm for designing a bandersnatch directly from its specification. Your company can take an n-word specification of a bandersnatch and, in about n3 steps, can test if the specification is reasonable and design an optimal bandersnatch that meets it. With your algorithm, a typical 15,000 word bandersnatch specification takes about one month to design. Construction only takes a week, so design dominates the bandersnatch building process. Your competitors, on the other hand, do not have a fast algorithm for producing optimal bandersnatch designs. The best that they can do is an exhaustive search through the approximately 2n/150 possible different designs that meet the specification looking for the best one. Since this exhaustive search for the typical size of specification would take a while (say, 1016 years, assuming one design per microsecond) your competitors must be content with the suboptimal designs that they can produce in about the same time as you. At least that was until yesterday. Seeing the value of research, your competition formed a consortium and also invested in computer science. They too have discovered the feasible optimal bandersnatch design algorithm. Since design dominates the production process, your bosses decide that the way to regain your company's competitive advantage is to reduce the design time. They give you the task of dramatically speeding up the design process. Like most modern computer scientists you begin working on the problem by reading the news on the Net. One day an ad catches your eye. Sensing its corporate salvation, your company orders one of the machines. When it arrives you unpack it and discover that its architecture is very simple.
Approximating P-Complete Problems
Authors: Greenlaw Raymond , Hoover H. James , Ruzzo Walter L.
Published: November 2020

Suppose that finding the solution to a problem is P-complete. It is natural to ask if it is any easier to obtain an approximate solution. For decision problems this might mean considering the corresponding combinatorial optimization problem. That is, a problem in which we try to minimize or maximize a given quantity. As one might expect from the theory of NP-completeness, the answer is both yes (for example in the case of Bin Packing, Problem A.4.7) and no (for example in the case of the Lexicographically First Maximal Independent Set Size Problem, see Lemma 10.2.2.). There are several motivations for developing good NC approximation algorithms. First, in all likelihood P-complete problems cannot be solved fast in parallel. Therefore, it may be useful to approximate them quickly in parallel. Second, problems that are P- complete but that can be approximated well seem to be special boundary cases. Perhaps by examining these types of problems more closely we can improve our understanding of parallelism. Third, it is important to build a theoretical foundation for studying and classifying additional approximation problems. Finally, it may be possible to speed up sequential approximation algorithms, of NP-complete problems, using fast parallel approximations. Our goal in this section is to develop the basic theory of parallel approximation algorithms. We begin by showing that certain P-complete problems are not amenable to NC approximation algorithms. Later we present examples of P-complete problems that can be approximated well in parallel. We start by considering the Lexicographically First Maximal Independent Set Problem, introduced in Definition 7.1.1, and proven P-complete in Problem A.2.1. As defined, LFMIS it is not directly amenable to approximation. We can phrase the problem in terms of computing the size of the independent set. Definition 10.2.1 Lexicographically First Maximal Independent Set Size (LFMISsize) Given: An undirected graph G = (V, E) with an ordering on the vertices and an integer k. Problem: Is the size of the lexicographically first maximal independent set of G less than or equal to k ? The following lemma shows that computing just the size of the lexicographically first maximal independent set is P-complete.
Recent Experiences With Prospector II
Authors: McCammon Richard B.
Published: November 2020

Three recent case studies in which Prospector II was used illustrate a variety of constructive responses that contribute to regional mineral resource assessments. The case studies included a group of precious-metal vein deposits in the Quartzville Mining District in Oregon, United States; a stratabound gold-silver deposit in Manitoba, Canada; and an Archean tin deposit from Western Australia. In each case, the objective was to see how Prospector II would classify the deposit in terms of deposit models in the Cox-Singer compendium. The precious-metal vein deposits in the Quartzville Mining District were interpreted by Prospector II to be part of a larger system likely to contain porphyry copper deposits. The stratabound gold-silver deposit in Manitoba fit the description of the Homestake gold deposit model. The Archean tin deposit from Western Australia bore little resemblance to any of the tin deposit models in the Cox-Singer compendium. In recent years, quantitative mineral resource assessments have gained recognition among land managers and national policymakers, who have found that numerical measures of potential mineral values are essential when considering alternative strategies. Such quantitative assessments allow land managers to plan optimum use of public lands and allow national policymakers to assess the need for securing long-term mineral supplies from international sources. In addition, quantitative assessments encourage the discovery and development of new deposits. Significant advances have been made in developing new techniques for the quantitative assessment of metallic mineral resources (Drew et al, 1986; Reed et al., 1989). In large part, these techniques are based on an earlier method of regional mineral resource assessment proposed by Singer (1975) and subsequently applied to areas in Alaska. The technique is based on the size distribution of mineral deposits of specified geologic types and on the probability of deposit occurrence. This approach to the quantitative assessment of undiscovered mineral resources is being applied to many of the mineral resource assessments being carried out by the U.S. Geological Survey (USGS) (Singer and Cox, 1988). Critical in this approach to quantitative assessment is the geologist's ability to relate the geologic environment in an area to specific deposit types.
Characteristic Analysis As An Oil Exploration Tool
Authors: Chaves H. A. F.
Published: November 2020

Characteristic analysis is well known in mineral resources appraisal and has proved useful for petroleum exploration. It also can be used to integrate geological data in sedimentary basin analysis and hydrocarbon assessment, considering geological relationships and uncertainties that result from lack of basic geological knowledge, A generalization of characteristic analysis, using fuzzy-set theory and fuzzy logic, may prove better for quantification of geologic analogues and also for description of reservoir and sedimentary facies. Characteristic analysis is a discrete multivariate procedure for combining and interpreting data; Botbol (1971) originally proposed its application to geology, geochemistry, and geophysics. It has been applied mainly in the search for poorly exposed or concealed mineral deposits by exploring joint occurrences or absences of mineralogical, lithological, and structural attributes (McCammon et al., 1981). It forms part of a systematic approach to resource appraisal and integration of generalized and specific geological knowledge (Chaves, 1988, 1989; Chaves and Lewis, 1989). The technique usually requires some form of discrete sampling to be applicable—generally a spatial discretization of maps into cells or regular grids (Melo, 1988). Characteristic analysis attempts to determine the joint occurrences of various attributes that are favorable for, related to, or indicative of the occurrence of the desired phenomenon or target. In geological applications, the target usually is an economic accumulation of energy or mineral resources. Applying characteristic analysis requires the following steps: 1) the studied area is sampled using a regular square or rectangular grid of cells; 2) in each cell the favorabilities of the variables are expressed in binary or ternary form; 3) a model is chosen that indicates the cells that include the target (Sinding-Larsen et al, 1979); and 4) a combined favorability map of the area is produced that points out possible new targets. The favorability of individual variables is expressed either in binary form— assigning a value of +1 to favorable and a value of 0 to unfavorable or unevaluated variables—or in ternary form if the two states represented by 0 are distinguishable—the value +1 again means favorable, the value —1 means unfavorable, and the value 0 means unevaluated.
Milankovitch Cyclicity In The Stratigraphic Record— A Review
Authors: Kelly S.B. , Cubitt J.M.
Published: November 2020

The Milankovitch or astronomical theory of paleoclimates relates climatic variation to the amount of solar energy available at the Earth's surface. The theory helps explain periodic, climatically related phenomena such as the Pleistocene ice ages. Identification of Milankovitch cyclicity within sediments demonstrates the influence of climate on sedimentation patterns and creates a time frame for the estimation of basin subsidence rates. Spectral analysis of deep sea and ice cores indicates periodic climatic fluctuations during Tertiary and Quaternary times. These fluctuations are strongly cyclical with low frequencies centered at periods around 400 ka and 100 ka together with shorter periodic components of approximately 41 and 21 ka. Lower frequencies reflect eccentricity of the Earth's orbit; 41- and 21-ka components are associated with periodic changes in the tilt of the Earth's axis and the precession of the equinoxes. Astronomically forced glacial eustasy results in distinct stratigraphic units or parasequences of widespread extent. Milankovitch band parasequences occur in both carbonate and clastic shelf systems, including cyclothemic Upper Paleozoic successions of North America. During the 1920's and 30's the Serbian mathematician Milutin Milankovitch studied cyclical variations in three elements of the Earth-Sun geometry: eccentricity, precession, and obliquity, and was able to calculate the Earth's solar radiation history for the past 650 ka (Milankovitch, 1969). Berger (1978, 1980) accurately determined the periodicities of the three orbital variations. Eccentricity—The Earth's orbit around the Sun is an ellipse; this results in the seasons. The eccentricity of the Earth's orbit periodically departs further from a circle and then reverts to almost true circularity. Periodicities are located around 413, 95, 123, and 100 ka. Secondary peaks appear to be located around 50 and 53 ka. There are further important periodicities at 1.23, 2.04, and 3.4 ma (Schwarzacher, 1991). Precession—Precession refers to variation in time of year at which the Earth is nearest the Sun (perihelion). This variation is caused by the Earth wobbling like a top and swiveling on its axis. Periodicities of 23,000, 22,400, 18,980, and 19,610 yr are recognized and often simplified to two periods of 19 and 23 ka. Secondary peaks are also located around 30 and 15 ka.