bluuebunny/crossref_metadata_2025 huggingface dataset:
Preform Design in Metal Forming
Authors: Kobayashi Shiro , Oh Soo-Ik , Altan Taylan
Published: November 2020

Preform design in metal forming refers to the design of an initial shape of the workpiece that, when it has undergone an associated forming process, forms the required product shape with desired property successfully without formation of defects and without excessive waste of materials. A carefully selected preform can contribute significantly to the reduction of the production costs. Preform design problems are encountered in various metal-forming processes, such as closed-die forging, shell nosing, rolling, and sheet-metal forming. Design of an optimal preform shape requires simultaneous determination of optimal process conditions. However, we are here concerned with the determination of the best preform shape under a given set of process conditions. In this chapter, a new method of “backward tracing” is introduced as an alternative approach to the solution of preform design, and the applications of this method to some specific processes are discussed. Similarly to the forward simulation technique, the backward tracing method uses the finite-element method. The forward simulation technique has been discussed in the previous chapters. Backward tracing refers to the prediction of the part configuration at any stage in a deformation process, when the final part geometry and process conditions are given. The concept is illustrated in Fig. 15.1. At time t = t0, the geometrical configuration x0 of a deforming body is represented by a point Q. The point Q is arrived at from the point P, whose configuration is given as x0–1 at t = t0–1, through the displacement field during a time-step Δt, namely, x0 = x0–1 + u0–1 Δt, where u0–1 is the velocity field at t = t0–1. Therefore, the problem is to determine u0–1, based on the information (x0) at point Q. The solution scheme is as follows: taking a loading solution u0 (forward) at Q, a first estimate of P can be made according to P(1) = x0 – u0 Δt.
The Future
Authors: Tossell John A. , Vaughan David J.
Published: November 2020

In this final chapter, an attempt is made to provide an overview of the capabilities of quantum-mechanical methods at the present time, and to highlight the needs for future development and possible future applications of these methods, particularly in areas related to mineral structures, energetics, and spectroscopy. There is also a brief account of some new areas of application, specific directions for future research, and possible developments in the perception and use of quantum-mechanical approaches. The book ends with an epilog on the overall role of “theoretical geochemistry” in the earth and environmental sciences. The local structural characteristics of minerals such as Mg2SiO4, which contain only main-group elements, are reasonably well reproduced by ab initio Hartree-Fock-Roothaan (SCF) cluster calculations at the mediumbasis- set level. Calculations incorporating configuration interaction will inevitably follow and probably lead to somewhat better agreement with experiment. The most pressing needs in this area of study are for the development of systematic procedures for cluster selection and embedding, for a greater understanding of the results at a qualitative level, and for more widespread efficient application of the quantum-chemical results currently available. In the last area, substantial progress has already been made by Lasaga and Gibbs (1987), Sanders et al. (1984), Tsuneyuki et al. (1988), and others, who have used ab initio calculations to generate theoretical force fields which can then be used in molecular-dynamics simulations. If the characteristics of the resultant force fields can be understood at a first-principles level, then it may be possible to understand details of the simulated structures at the same level. Unfortunately, as regards a greater qualitative understanding of the quantum-mechanical calculations, little progress has been made. Rather old qualitative theories describe some aspects of bond-angle variation (Tossell, 1986), but no general model to interpret variations in bond lengths has been developed within either chemistry or geochemistry beyond the model of additive atomic (Slater) or ionic (Shannon and Prewitt) radii. Indeed, global theories of bond-length variations within an ab initio framework seem to be nonexistent. Nonetheless, quantum-chemical studies have shown the presence of intriguing systematics in bond lengths (Gibbs et al., 1987), which had been already noted empirically.
Self-Referential Systems
Authors: Smullyan Raymond M.
Published: November 2020

Self-Referential Systems This chapter is largely a review of the essential ideas behind the proofs of Gödel, Rosser and Löb—only presented in a more abstract setting. We believe that it will tie up these ideas in a helpful and instructive manner. We shall first present these ideas in the form of logic puzzles (much in the manner of Smtdlyan [1987]). Then we shall state the results more generally in terms of abstract systems that we call provability systems. These are closely related to certain axiom systems of modal logic, which we briefly discuss at the end of the chapter. In the puzzles to which we now turn, belief will play the rôle of provability. Instead of considering a mathematical system and the sentences provable in it, we consider a logician (sometimes call a reasoner) and the propositions believed by the reasoner. Apart from the heuristic value, these “epistemic” incompleteness theorems appear to be of some interest to those working in artificial intelligence. We shall pay a visit to the Island of Knights and Knaves, in which knights make only true statements and knaves make only false ones. Each inhabitant is either a knight or a knave. No inhabitant can claim that he is not a knight (since a knight would never make such a false claim and a knave would never make such a true claim). A logician visits this island one day and meets a native. All we are told about the logician is that he is completely accurate in his beliefs—he never believes anything false. The native then makes a certain statement X. It then follows that the logician can never believe that the native is a knight nor can he ever believe that the native is a knave.
Chordata
Authors: Lowenstam Heinz A. , Weiner Stephen
Published: November 2020

In the field of biomineralization the phylum Chordata is the most intensively studied, as one of its subphyla, the Craniata, includes our own species. The Craniata are often referred to as the vertebrates, a term that alludes to the importance of the endoskeleton in denning the essential character of these animals. The phylum Chordata also contains three other subphyla, only one of which has members that form mineralized hard parts. They belong to the Urochordata or tunicates. In fact, mineralization is confined to several families of a single class of urochordates, the Ascidiacea. Table 9.1 is a compilation of the known biogenic minerals formed by members of the Chordata, together with the sites at which they form and their presumed functions. The table includes no less than 17 different minerals, which should dispel any notion that mineralization in the chordates is synonymous with "calcium phosphate" deposition. It is, of course, true that the mineralized skeletal hard parts of most of the Craniata or vertebrates contain a calcium phosphate mineral, usually in the carbonated form called dahllite. However, the vertebrates also form four different carbonate minerals that are most commonly found in the vestibulary apparatus (see Chapter 10). They form three different iron minerals, which includes magnetite found in the navigation system of various vertebrate genera. The Ascidiacea also form a diverse array of minerals. Interestingly, however, their diversity is essentially confined to one class, the Pyuridae, which form no less than six different minerals, including two phosphate minerals. In this chapter we first describe biomineralization processes in the Ascidiacea followed by detailed discussions of mineralization processes in the Chordata or vertebrates. For convenience, the section on vertebrate mineralization is divided according to the major mineralized tissues: bone (dentin), cartilage, and tooth enamel. Mineralization in the vestibulary apparatus is discussed in Chapter 10.
Academic Development and Social Change: Higher Education in Massachusetts before 1945
Authors: Freeland Richard M.
Published: November 2020

In October 1948, James B. Conant, president of Harvard, journeyed from Cambridge across the Charles River to address the fiftieth anniversary convocation of Northeastern University. Though the ceremonies on N.U.’s new Hungtington Avenue campus occurred only two miles from Conant’s offices in Harvard Yard, in academic terms the two settings could not have been separated by a greater distance. Harvard was the nation’s richest and most distinguished institution of higher education, the alma mater of generations of regional and national leaders in government, business, and academia. Northeastern, only recently cut loose from the Y.M.C.A., still struggling to obtain proper facilities, was an obscure, local school offering practical training to working-class students. Indeed, Conant’s appearance at Northeastern eloquently symbolized the variations that existed among institutions that called themselves “universities” in the United States at the end of World War II, and Harvard’s president made these differences the subject of his talk, which he titled “Diversity in American Education.” Conant’s speech was a hymn to institutional variety as an academic characteristic particularly appropriate for a democracy. “There would be a contradiction in terms,” Conant said, “if we had an American system,” in the sense of an organization “logically constructed, well-integrated ... and administered from the top down” like those of continental Europe. The opportunity of individuals from any background to better their positions in this country’s “fluid and free society” would be inhibited by centralization. For Conant, the colleges and universities of Massachusetts illustrated democratic higher education at its best. “We have here in this section of New England,” he observed,...a number of academic organizations designed to provide educational facilities for young men and women... These institutions are diverse in their history and their specific objectives and cover a wide spectrum of educational opportunity. Between us there are but few gaps in the type of advanced instruction we offer. We each have our own mission.. . Taken as a whole [we] represent as diversified a program of post-high school education as can be found in the United States. In celebrating the variability of the nation’s universities, Conant found an ideal way to narrow the embarrassing difference in status between himself and his hosts.
The Institutional Complex and Academic Adaptation, 1945–1980
Authors: Freeland Richard M.
Published: November 2020

Change among universities in Massachusetts during the golden age illustrated the pervasive tendency of academic institutions, linked as they were to historic social divisions, to seek higher status. With essential resources readily available, these campuses converged from disparate prewar positions toward the functions and values of the research university, the dominant model of excellence in the postwar period. The inclination to pursue common goals was circumscribed, however, because the circumstances of change were always specific and resources were never infinite. Local variations in competitive conditions combined with other elements of the institutional complex—academic ideas and organizational dynamics—to channel campus ambitions and preserve elements of diversity. The new conditions of the 1970s further demonstrated the relationship between competition and diversity while testing the durability of initiatives launched in years when growth was easy. With resources now more constrained, universities were compelled to craft their strategies of change more carefully and pay closer attention to their particular strengths and characteristics. Still, campus priorities in the decade following the golden age revealed the extent to which institutional ambitions tend to take precedence over educational ideas. Efforts to pursue the most important reform proposals of the late 1960s and early 1970s were repeatedly subordinated to the protection of institutional interests in the face of new and challenging competitive pressures. In the closing section of Chapter 2, we considered the forces that produced change among universities in the golden age as understood by commentators at the end of the period. These accounts stressed two phenomena: the increased demands of society for academic services and the enlarged power of the academic professions. In the face of these nonacademic and extrainstitutional pressures, it was widely argued, individual universities were largely reactive, more carried by currents they could not control than aggressive in shaping their own futures. The postwar histories of universities in Massachusetts, as we have encountered them in the last four chapters, demonstrated the importance of macrolevel causes of institutional change but also focused attention on the initiative exercised by campus leaders within an academic marketplace still dominated by interinstitutional competition.
Race and Gender in the Shaping of the American Literary Canon A Case Study from the Twenties
Authors: Lauter Paul
Published: November 2020

In its original form this chapter was delivered at a late-1970s forum sponsored by the Commission on the Status of Women in the Profession of the Modern Language Association. It had a kind of underground, mimeographed existence for a few years before seeing print in Feminist Studies in 1983. It has made its way and continues, I think, to be useful for those studying the canon. I have therefore not undertaken to change it. Judith Fetterley has raised one important criticism of the piece. In her fine introduction to Provisions: A Reader From 19th-century American Women (Bloomington: Indiana University Press, 1985, pp. 18–19) she argues that the exclusion of nineteenth-century women writers from the literary canon began far earlier than the 1920s, in fact during the nineteenth century itself. There is significant evidence to support that contention. John Macy’s 1911 volume The Spirit of American Literature, for example, devotes its sixteen chapters to sixteen white men, though his “Preface” expresses admiration for the work of Jewett, Freeman and Wharton, and even passingly for Stowe. Brander Matthews’ similar volume, An Introduction to the Study of American Literature (1896, rev. 1911), focuses fifteen chapters on individual white men and then devotes one to “other writers,” including Whitman and Stowe. These very likely reflected the state of much academic opinion, though volumes like An American Anthology, 1787–1900 (ed., Edmund Clarence Stedman, 1900) and Mildred Cabell Watkins’ young adult primer, American Literature (1894) offer countervailing evidence. And, of course, as I outline in the article, other older academics like Fred Lewis Pattee and Arthur Hobson Quinn offered a far wider version of American letters. Fetterley thus provides what I think is a useful corrective to broad generalizations about academic canons, especially with respect to early and mid-nineteenth-century writers. But the central point, in my view, is that dominantly male academic accounts of the American canon were far less weighty around the turn of the century than they became in and after the 1920s.
Conclusion
Authors: Lamberti Marjorie
Published: November 2020

In the imperial era schoolteachers and left-wing liberals in Prussia viewed the confessional school under the supervision of school inspectors who were clergymen as an anachronism in a modern society. Its survival defied their expectation that demographic mobility and urbanization would increase the confessional mixture of the school enrollments and disproved their contention that the imperatives of national and social integration should make interconfessional schooling the goal of every modern state. Disheartened and demoralized after years of striving in vain to achieve their pedagogic ideal, the leaders of the Prussian Teachers’ Association could not easily admit or accept the reasons for their failure. After the enactment of the school law of 1906, they contrived an explanation—“they wanted to fight Social Democracy through the law”—that obscured their inability to influence public opinion and the programs of the major parties and obviated a more probing investigation of why the political conflicts over the school question stretching over half a century ended with a law that made confessional schooling the rule. The alarm of the governing class over the growth of the Social Democratic party affected the fate of school reform in Prussia far less than the experience of introducing the changes at the height of a religiopolitical conflict that deepened the divisions within the nation. The circumstances in which the interconfessional schools were opened in the 1870s gave them the reputation of being a “Kulturkampf institution” and this unfortunate association of school reform with Kulturkampf politics remained in the consciousness of both Catholics and Protestants for years to come. Although the Ministry of Education under Adalbert Falk formulated a moderate and prudent policy for establishing interconfessional schools gradually with some consideration to the pedagogic benefits of the innovation, the liberals who agitated for the reform and the city officials who introduced it were more radical and were motivated by political objectives as well as by educational interests. The campaign for school reform became entangled in the political battle that zealous Kulturkdmpfer waged against the Catholic church and the Center party. The introduction of interconfessional schooling did not have popular consent.
Components of Industry
Authors: Gordon Robert B. , Malone Patrick M.
Published: November 2020

Industry uses technical and organizational skills, engineering knowledge, and energy to transform natural resources into useful products. (Our definition of industry excludes such late-twentieth-century coinages as “banking industry,” “leisure industry,” and “culture industry.”) When we carry on industry, we alter the landscape by using natural resources, by releasing wastes, and by building workplaces, industrial communities, and transportation systems. The components of industry include the skills and technical knowledge of the participants as well as the landscape and natural resources devoted to industrial activity. We cover the industrial landscape in Part II; in this chapter, we introduce the human and natural resources used by industry. The work skills of artisans, the organizational skills of managers and entrepreneurs, and the engineering skills of designers and innovators have always been as essential as natural resources to industrial success. Although scientific skills had relatively little place in most industrial enterprises until the late nineteenth century, they are now essential to the success of many industries. The skills in consideration here are the mental and physical capacities of individuals to do difficult tasks. These “genuine” skills are not necessarily the same as the “socially constructed” skills that are defined by job descriptions or established as barriers to control entry into a trade or profession. Among work skills, those of artisans are the most poorly re corded and are, consequently, the most difficult for historians to interpret; additionally, artisan’s skills are sometimes ignored, or even denigrated, by authors seeking to describe industrial work in terms of exploitation of workers or to inflate the accomplishments of inventors or entrepreneurs. Some skills that were essential in industrialization, sueh as those used in mining and burning coal, are hardly described in the historical record because they developed gradually and were difficult for observers to perceive. Firing a furnace with coal seems to be a simple, physically demanding task, but it requires judgment and experience to do well in a locomotive, a crucible steelworks, a glasshouse, or other heat-using industries. The stoker’s skill often went unrecognized until attempts were made to transfer technology dependent on burning coal elsewhere.
Work in Factories
Authors: Gordon Robert B. , Malone Patrick M.
Published: November 2020

Factories, and the factory system, are at the heart of the American industrial experience. Since the 1790s, Americans have developed many different types of factories and varieties of work within each of them. It is a terrible mistake to think of factory workers as simply automatons who do some type of mindless, repetitive task, day in and day out. The average American has never been in a factory and knows very little about what actually goes on there. Typically, there are dozens of employee classifications in one of these highly organized and hierarchical workplaces. A person employed in a factory might be a sweeper, vatman, machine operator, machine fixer, machinist, toolmaker, millwright, stockroom supplier, shipper, overseer, foreman, draftsman, electrician, or engineer. Machine operation, only one form of factory work, requires widely varying levels of skill, depending on the type of machine and the pace of production. Some jobs are routine and undemanding, but others challenge the intellect and manual dexterity of even the most skilled and experienced employees. There are tasks to be performed by one person as well as group activities that require extensive social interaction. The work culture of the factory is, and has always been, far more complex and dynamic than an organizational chart would imply. Although factory work frequently included operations done by hand and processes that did not require any motive power, all true factories used some power-driven machinery. Mechanization was a key element in the development of the factory system. Additionally, the owners of many factories followed the principle of uniformity, aiming to make standardized products from parts that were, to some degree, interchangeable. The first American factories, as we have seen in Chapter 8, were textile mills; but soon after Americans began to make yarn in places like the Slater Mill, they were also shifting the manufacture of products such as clocks, firearms, and edge tools from craft shops to factories. In the 1790s, Samuel Slater’s youthful operatives tended a sequence of special-purpose machines powered by a waterwheel.
Induction
Authors: Pollock John L.
Published: November 2020

The objective of this book is to provide an analysis of nomic probability in terms of its conceptual role. This requires an account both of what inferences can be drawn from nomic probabilities, and how nomic probabilities can be evaluated on the basis of nonprobabilistic information. We have an account of. That consists of the acceptance rules and the theory of direct inference. The theory of nonclassical direct inference also provides a partial account of. Some nomic probabilities can be evaluated in terms of others by using nonclassical direct inference. But in order to get this process started in the first place, there must be some other way of evaluating nomic probabilities that does not require any prior contingent knowledge of the values of such probabilities. It seems intuitively clear that that is accomplished by some kind of statistical induction. In statistical induction, we observe a sample of B’s, determine the relative frequency of A’s in that sample, and then estimate prob(A/B) to be approximately equal to that relative frequency. A close kin to statistical induction is enumerative induction, wherein it is observed that all of the B’s in the sample are A’s, and it is concluded that any A would be a B, that is, A ⇒ B. There are two possibilities regarding statistical and enumerative induction. They could be derivable from more basic epistemic principles, or they might be irreducible constituents of the conceptual role of nomic probability and nomic generalizations. These two possibilities reflect what have come to be regarded as two different problems of induction. The traditional problem of induction was that of justifying induction. But most contemporary philosophers have forsaken that for Goodman’s “new riddle of induction”, which I am construing here as the problem of giving an accurate account of correct principles of induction. This change in orientation reflects the view that principles of induction are basic epistemic principles, partly constitutive of rationality, and not reducible to or justifiable on the basis of anything more fundamental. I endorsed the latter view in my [1974], but now I am convinced that it is false.
Advanced Topics: Direct Inference
Authors: Pollock John L.
Published: November 2020

It was argued in Chapter 1 that various kinds of propensities make intuitive sense, but existing propensity theories do little to clarify their nature. We are now in a position to give precise definitions for several different kinds of propensities in terms of nomic probabilities. The characteristics of these propensities can then be deduced from the theory of nomic probability. The technique for defining propensities in terms of nomic probabilities is modeled on the definitions of objective and physical/epistemic definite probabilities proposed in Chapter 4. We often want to know how probable it is that P would be true if Q were true. This is a kind of counterfactual probability, and I will symbolize it as ┌prob(P/Q)┐. Counterfactual conditionals constitute the limiting case of counterfactual probability, in the sense that if (Q > P) obtains then prob(P/Q) = 1. prob(PlQ) is to be distinguished from prob(P/g) and PROB(P/(2), either of which can be regarded as an “indicative” probability that P is true if Q is true. Recall that (Q > P) obtains iff P obtains at every nearest world at which Q obtains. In other words, where M(0 is the set of nearest ^-worlds, (Q > P) obtains iff M(Q) ⊆ |P|. Analogously, prob(P/Q) can be regarded as a measure of the proportion of nearest g-worlds that are also P-worlds. This has the immediate result that if (Q > P) obtains then prob(PIQ) = 1 (but not conversely). This sort of heuristic description of counterfactual probability enables us to investigate its formal properties, but if the notion is to be of any real use we must do more than wave our hands and talk about an unspecified measure on M(Q). We are now in a position to accurately define counterfactual probability. Let CQ be the conjunction of all of the counterfactual consequences of Q, that is, the conjunction of all states of affairs R such that (Q > R) obtains.
The Popular Front on Campus
Authors: Cohen Robert
Published: November 2020

The international threat posed by fascism became the central concern of the student movement during the second half of the Depression decade. For this generation of college students not a year passed without some ominous reminder of the rising strength, belligerence, arid brutality of European fascism. There was Italy’s invasion of Ethiopia in 1935, Hitler’s and Mussolini’s military support of the Spanish fascist revolt in 1936 and 1937, Germany’s anti-Jewish pogrom and conquest of Austria in 1938, and the Nazi invasion of Czechoslavakia and Poland in 1939. These events, along with Japan’s escalating war on China, prodded many student activists to rethink the isolationist assumptions their anti-war movement had popularized on campus in the early 1930s. The increasing aggression of the fascist powers led these activists to worry that the very neutrality that their movement had urged upon the United States to promote peace, instead, bred war by preventing America from orchestrating an international effort to thwart fascist expansionism. This mindset facilitated the rise of a major challenge to isolationism within the student movement, which by 1938 pushed the movement’s largest organizations to abandon their isolationist policies and embrace collective security. The first influential group within the student movement’s leadership which sought to shift the movement away from isolationism was the communists. These radicals had the earliest and clearest vision of the student movement’s need for a more explicitly anti-fascist foreign policy. Their thinking on this matter had been strongly influenced by deliberations of the Seventh World Congress of the Communist International (CI) in August 1935. The CI became concerned about the triumph of Nazism in Germany, its spreading influence in Europe, and the potential threat these developments posed to the U.S.S.R.’s security. The Seventh World Congress therefore urged the formation of broad national coalitions and international collective security arrangements on behalf of a Popular Front against fascism. For communists in the American student movement, this implied the need to turn the movement’s foreign policy away from American neutrality and toward the endorsement of collective efforts among the United States, the Soviet Union, and other anti-fascist states to prevent military aggression by Germany, Italy, and Japan.
Vowels
Authors: Treiman Rebecca
Published: November 2020

In this chapter, I focus on vowel phonemes. Because a study that is strictly based on a distinction between legal and illegal spellings has some serious problems, this chapter employs a more descriptive and qualitative approach. I discuss how the first graders in the study spelled each vowel phoneme of English. What do the children’s spellings reveal about their knowledge of the English writing system and about their knowledge of spoken English? The analyses reported in Chapter 3 uncovered some factors that affect how children spell phonemes. For the children in this study, the most important of these factors was exposure to phoneme-grapheme correspondences in printed words: Children used frequent correspondences more often than infrequent correspondences. Another factor was letter names: Children used correspondences in which the name of the grapheme contained the phoneme more often than correspondences in which the name of the grapheme did not contain the phoneme. A third factor was formal teaching: Children were more often correct on correspondences that were taught in the classroom than on correspondences that were not directly taught. In this chapter, I ask how these and other factors influenced the children’s spelling of specific vowel phonemes. Sometimes, the children’s choices of spellings for vowel phonemes mirrored the choices embodied in the English writing system. The children used the spellings that occur most frequently in English, whether or not these spellings were explicitly taught. In other cases, the children’s choices did not mirror the conventional ones. There are two different ways in which this occurred. First, the children sometimes used a spelling that is illegal in the conventional system; that is, a grapheme that never represents the phoneme. In these cases, something other than knowledge of conventional spelling must explain the “invented” spelling. I ask what the reasons are. In discussing these illegal substitutions, I have chosen, somewhat arbitrarily, a cut-off of 2.5%. Illegal substitutions that occurred at rates of 2.5% or more out of all spellings are singled out for discussion. A second way in which children’s choices sometimes failed to mirror those of conventional English was in overuse of particular spellings.
Between Clinic and Laboratory: Students and Teaching at Midcentury
Authors: Bonner Thomas Neville
Published: November 2020

Despite the gathering momentum for a single standard of medical education, the portals of access to medicine remained remarkably open at the middle of the nineteenth century. From this time forward, governments and professional associations—in the name of science and clinical knowledge and the protection of the public’s health—steadily limited further entrance to medicine to those with extensive preparatory education and the capacity to bear the financial and other burdens of ever longer periods of study. But in 1850, alternative (and cheaper) paths to medicine, such as training in a practical school or learning medicine with a preceptor, were still available in the transatlantic nations. Not only were the écoles secondaires (or écoles préparatoires) and the medical-surgical academies still widely open to those on the European continent without a university-preparatory education, but British and American training schools for general practitioners, offering schooling well below the university level, were also widely available to students and growing at a rapid pace. “The establishment of provincial medical schools,” for those of modest means, declared Joseph Jordan of Manchester in 1854, was an event “of national importance. . . . Indeed there has not been so great a movement [in Britain] since the College of Surgeons was established.” A decade before, probably unknown to Jordan, a New York professor, Martyn Paine, had voiced similar views about America’s rural colleges when he told students that “no institutions [are] more important than the country medical schools, since these are adapted to the means of a large class of students . . . [of] humble attainments.” In both Britain and America, according to Paine’s New York contemporary John Revere, the bulk of practitioners “are generally taken from the humbler conditions in society, and have few opportunities of intellectual improvement.” The social differences between those who followed the university and the practical routes to medicine were nearly as sharp as they had been a halfcentury before. Even when a medical degree was awarded after what was essentially a nonuniversity education, as it was in the United States, Paine distinguished between graduates of country schools, “where lectures and board are low,” and “the aristocrats of our profession, made so through the difference of a few dollars.”
The Second Law of Thermodynamics
Authors: Anderson Greg M. , Crerar David A.
Published: November 2020

We have seen that the first great principle of energy transfers is that energy is conserved. The essence of the second principle or law has to do with energy availability, or with the "directionality" of these transfers (processes). In other words, it is observed that once the constraints on the beginning and ending states are decided upon, processes can only proceed spontaneously in one direction between these states and are never observed to proceed in the other direction unless they are "pushed" with an external energy source. For example, a brick can fall off a table onto the floor. The potential energy it has on the table is converted to kinetic energy and then to a certain amount of heat and mechanical deformation (work) upon impact. According to the first law, the energy expended on impact will exactly equal the energy the brick had on the table. Bricks have never been observed to spontaneously cool themselves, convert this heat energy into kinetic energy, and fly from the floor to the table. Such events could exactly satisfy the first law, which clearly has nothing to say about why they don't happen—just that if they did happen, energy would be conserved. It would obviously be very useful to have a method of predicting which way a given process would go under given conditions. It would open the way towards systematizing chemical and mineral reactions, for one thing. We could start to predict which minerals would form under given metamorphic conditions, for example, and perhaps even predict their compositions, because all such changes are simply processes that can be considered to go from one equilibrium state to another. Possibly the greatest single step forward in the history of the development of thermodynamics was the recognition and definition of a parameter, the entropy, which enables such predictions and systematizations to be made. deduced on the basis of years of experience, and then show through use of the Carnot cycle the logical consequences (such as the existence of the entropy and an absolute scale of temperature).
Heterogeneous and Open Systems
Authors: Anderson Greg M. , Crerar David A.
Published: November 2020

Up to this point, with minor exceptions, we have discussed only closed systems, that is, systems having a fixed composition, and have for the most part not bothered to consider whether the system was homogeneous (one phase) or heterogeneous (more than one phase). We must now explicitly consider the implications of having more than one phase, and of the transfer of matter between phases and into and out of the system. There are two kinds of open systems that concern us, illustrated in Figure 14.1. In the first kind, the open system is simply a separate phase in a system that is closed overall, illustrated in Figure 14.la. The phases are free to change composition by exchange of components in response to changes in the conditions (say P and T) of the closed system. The phases in a crystallizing magrna are examples of open systems in this sense. In the second kind we distinguish the system from an environment, joined by means of a membrane permeable only to certain components (Figure 14. Ib). This enables the system to change composition in response to conditions in the environment, which may be quite different from those in the system. The membrane may be real, as in the case of experimental systems in which hydrogen, having an externally controlled fugacity, diffuses into the system through the platinum walls of the system, or it may be imaginary, as when it is used to help clarify our thinking about metasomatic processes. Of course, if you think carefully about it, the difference between the two cases is not always very clear-cut. For example in the crystallizing magma, quartz and the melt in which it is crystallizing could be considered as the "environment" for the other crystallizing phases, controlling their chemical potential of SiO2. Nevertheless, the distinction is usually clear enough for our purposes. We will first consider open systems in the first sense in the derivation of the phase rule, and then consider cases of "membrane" or "osmotic" equilibria, which is the kind that the term "open system" has generally come to mean in geochemistry.
Solid Solutions
Authors: Anderson Greg M. , Crerar David A.
Published: November 2020

Real solutions of practical interest to Earth scientists do not behave ideally, although some do come fairly close. The problem of course lies in the stringent and unrealistic physical models we have prescribed for ideal solutions. The molecules of a gas do interact with each other, molecular forces within mixed component liquids really are non-uniform, and the different ions substituting for each other in solids are never exactly alike. So why bother defining an ideal solution in the first place if real systems do not behave that way? In fact, the ideal solution is a very useful artifice. It is something simple against which the behaviour of real solutions can be measured and compared. Our most fundamental definition of an ideal solution was With this as our reference, we can define a non-ideal solution as one for which the activity coefficient of each component i differs from unity The activity coefficient is the single quantity that expresses all deviations from non-ideality for each component of a solution. As we shall see, parameters other than the activity coefficient itself are frequently used to describe non-ideal behavior, but these could, if we wished, be related back to (15.1). Note that we say ⋎i, ≠1.0 in general; there are times when ⋎i = 1.0 for specific conditions (one set of T, P, Xi, etc.) even in highly non-ideal systems. This is just coincidental and certainly does not mean that the system is ideal at that particular point—the activity coefficient would have to be unity under all possible conditions for that to be the case.
Radiation
Authors: Kraus Eric B. , Businger Joost A.
Published: November 2020

The earth receives virtually all of its energy from the sun in the form of electromagnetic radiation. This radiation is absorbed, reflected, and scattered by the earth’s surface, the ocean, and the atmosphere. The absorbed radiation is transformed into heat and other forms of energy, and eventually it is returned to space as low-temperature terrestrial radiation. It is clear that radiation is of fundamental importance to atmosphere-ocean interaction. There exists an adequate body of literature on the subject from an introductory treatment by Fleagle and Businger (1980) to specialized monographs by Kondratjev (1969), Liou (1980), and Goody and Yung (1989). Here it will suffice to introduce the basic concepts and focus on the applications to the air-sea interface. Radiation in the atmosphere and ocean comes from all directions simultaneously. The radiation energy per unit time coming from a specific direction and passing through a unit area perpendicular to that direction is called the radiance, I. The irradiance, Fi, or radiant flux density, is the radiant energy that passes through a unit horizontal area per unit time coming from all directions above it. Therefore where θ is the zenith angle and dω is an infinitesimal solid angle. The cos θ reflects the projection of the horizontal unit area into the direction from where I comes. The limits 0 and 2π of the integral reflect the hemisphere of directions above the unit area. When the radiance is independent of direction it is called isotropic. Equation may then be integrated to yield The irradiance from below the unit area is also called exitance and is denoted by Fe. The net irradiance, Fn, is defined by For isotropic radiance, the net irradiance Fn = 0. The fluxes are positive when upward and negative when downward. The interactions between radiation and matter may take various forms. They include refraction, reflection, scattering, diffraction, absorption, and emission. All these interactions are described by the theory of electromagnetic waves (e.g., Panofsky and Phillips, 1962). The full theory will not be developed here, but a number of basic and useful relations will be introduced to describe the characteristics of the interactions mentioned previously.
The Orb
Authors: Gelernter David
Published: November 2020

To use a Mirror world program, you sit down at your computer, which has a large color screen and a connection to the local fiberoptic utility cable. (The screen and the cable are garden-variety technology today.) Or—if you’re willing to put up with a smaller picture and it’s a nice day—you pick up your laptop, tune in Data Radio and head for the hammock. In either case, you flip channels until you find the Mirror world of your choice, and then you see a picture. Capturing the structure and present status of an entire company, university, hospital, city or whatever in a single (obviously elliptical, high-level) sketch is a hard but solvable research problem. The picture changes subtly as you watch, mirroring changes in the world outside. But for most purposes, you don’t merely sit and stare. You zoom in and poke around, like an explorer in a miniature sub. At every level the display is live: it changes as you watch. You move a viewing-frame around the picture with a mouse or equivalent, probably equipped with knobs for zooming. You meet your software agents and other Mirror world visitors along the way. when your agents have developments to report, or when you choose to ask questions or plant new agents, you pop into a sub-screen that displays ordinary text. You can enter a Mirror world through any household computer, but a few extra controls come in handy. Your basic Mirror world computer is equipped with a perspective shifter, a diving mouse, a “history” key (with a time-travel velocity knob right next to it), the all-important “experience” key, and finally an “agent” key. There is the ordinary keyboard besides. (I’m describing hardware gadgets that are similar to what you can buy today at the corner computer store. If you plan to do lots of Mirror worlding, you’ll invest in the Mirror world Value Pack, or whatever; the extra gadgets are tacked onto the computer in the same way your mouse is attached. The “viewpoint shifter” probably looks like a joystick; the diving mouse is the same as any other mouse, but equipped with an altitude-control knob.
Optical Closure: from Theory to Measurement
Authors: Zaneveld J. Ronald V.
Published: November 2020

The intensity and spectrum of the light in the ocean have a major influence on the biological processes. These processes in turn determine the concentrations of much of the suspended and dissolved matter in the ocean, which affect the way in which the light is scattered and absorbed. These relationships can perhaps be most easily illustrated schematically as in Fig. 3-1. At the upper boundary we have the sun and sky radiances and the surface transmission conditions that combine to provide the energy entering through the surface. The ocean itself contains the vertical structure of those optical properties that do not depend on the structure of the light field, but depend only on the properties of the suspended and dissolved materials: the absorption coefficient a(λ,z), the beam attenuation coefficient c(λ,z), and the volume scattering function β(θ,λ,z). These are known as inherent optical properties, because they do not depend on the source radiance field (Preisendorfer, 1976). They are a function only of the suspended and dissolved materials in the water, and of the water itself. How does the vertical structure of the inherent optical properties affect the vertical structure of the radiance field in the ocean itself? This is the problem of radiative transfer in which we try to predict the intensity, direction, and spectrum of the light (spectral radiance) in the ocean, based on a set of given inherent optical properties. Those properties of the light field in the ocean that depend on the radiance are known as the apparent optical properties. Radiance field integrals, such as the vector irradiance, E(λ,z), the scalar irradiance E0(λ,z), and their attenuation coefficients are also apparent optical properties.