bluuebunny/crossref_metadata_2025 huggingface dataset:
The PC-User’s Guide to Colossus
Authors: Wells Benjamin
Published: November 2020

Personal computers (PCs) dominate today’s digital landscape. The two-letter name started with the 1981 IBM PC. Desktop machines based on single-chip microprocessors—and thus called microcomputers—were widely used before the IBM PC, but that is the name that has stuck. Many would consider a Packard-Bell tabletop computer of the early 1960s to be the first personal computer. But as far as single-user/operator commercial machines go, there is also the Bendix G15 from the mid-1950s, described in Chapter 9. PC users are likely to have forgotten or never known the atmosphere of early-generation computers. The ‘operating system’ was a schedule for the human staff who mounted large reels of tape, toggled inputs at the long control panel, pushed the load-and-run switch, and stacked punch cards and fanfold sheets of printed output. The numerous operators wore white lab jackets, worked in large air-conditioned spaces, and appeared to be high priests and acolytes in a vocational order. The users were supplicants. Apart from experimental machines at universities—such as MIT’s famed TX-0 (1955–6), which was controlled by the first computer hackers once it moved to the MIT campus in 1958—the users entreated the operators through written requests heading a card deck. Back then, the users as well as the general public stood behind a velvet rope, even a window wall. The operators continued to rule the machine long after users had electronic connection through time-sharing remote terminals. But those who had hacked the small machines like the TX-0 knew that the goal was the direct, immediate access of personal computers. Colossus already had that personal touch. Designed to be used by a single cryptanalyst assisted by one Wren, and later often run by the Wren solo, Colossus was in that sense a personal computer. But just how close was Colossus to being a PC? This chapter compares and contrasts the architecture of Colossus with that of today’s personal computers. An architect designs a building by balancing needs and functions with resources and aesthetics. The availability and cost of components constrain her work. Physical limitations and dynamics of use further impact on it. The building reflects the architect’s imagination and skill.
Mr Newman’s Section
Authors: Copeland Jack , Caughey Catherine
Published: November 2020

When Turing arrived at Bletchley Park, the day after Chamberlain’s announcement of war with Germany, he joined Dilly Knox’s Research Section. The job of the Research Section was to study enemy ciphers and operating procedures, and to devise methods of attack. The techniques invented by this high-powered think-tank were then handed over to other sections where they were used operationally against the enemy traffic. In 1939, Enigma was the focus of research. By the time Tutte joined the Research Section, in mid-1941, Captain Gerry Morgan headed it. Tunny soon became the leading problem. Thanks to Tutte, the Research Section broke the Tunny machine in January 1942, and in July read up-to-date traffic for the first time. Tunny could now be tackled operationally, and a Tunny-breaking section was immediately set up under Major Ralph Tester. Several members of the Research Section moved over to the ‘Testery’. Armed with Turingery and other hand methods, the Testery read nearly every message from July to October 1942—thanks to the insecure 12-letter indicator system (see Chapter 3). In October, however, the 12-letter indicators were replaced by QEP numbers and the Testery, now completely reliant on depths, fell on leaner times (see Chapter 5). The Research Section renewed its efforts against Tunny, looking for a means of wheel setting that did not depend on depths. With the invention of Tutte’s method, Newman was given the job of developing the necessary machinery, and when the Heath Robinson was delivered in June 1943 the ‘Newmanry’ became a separate section. From December 1943 the Newmanry would be responsible for breaking and setting the chi-wheels, and the Testery for breaking and setting the remaining wheels manually. The two sections worked hand-in-glove. Initially Newman’s staff consisted of one cryptographer (Michie), two engineers, and 16 Wrens. Soon a second cryptographer arrived (Good), and after three months of experimentation, two or three messages were being set each week. ‘Cryptographers’, ‘engineers’, and ‘Wrens’ remained the principal staffing categories of the Newmanry throughout the war. By May 1945, there were 26 cryptographers, 28 engineers, and 273 Wrens. During the period June 1943 to July 1944, two Americans joined the cryptographic staff of the Newmanry.
The New World and the Old
Authors: Nasaw David
Published: November 2020

The European visitors had much to marvel at in the New World they visited in the second quarter of the nineteenth century. Not least among the oddities encountered was what appeared to be a new breed of children. Mrs. Trollope, among the first to report on the situation, was not at all pleased with what she found. American children seemed to her a dirty, noisy, misbehaved, undisciplined, disrespectful lot. She confided to her readers that she was not the only gentlewoman who had come to this conclusion: “I have conversed with many American ladies on the total want of discipline and subjection which I observed universally among children of all ages, and I never found any who did not both acknowledge and deplore the truth of the remark.” The “ladies” may have “deplored” their children’s behavior, but most Americans did not. In fact, what seems to have disturbed the visitors even more than the children’s lack of manners was the parents’ lack of concern. Eneas MacKenzie was amazed that children were seated and served their tea with dirty faces, uncombed hair, and “evidently untaught” dispositions. He reported that all members of the American family “from the boy of six years up to the owner ... of the house appeared independent of each other.” A British naval officer reported the following scene he claimed to have overheard in 1837: . . . “Johnny, my dear, come here,” says his mama. “I won’t,’’ cries Johnny. “You must, my love, you are all wet, and you’ll catch cold.” “I won’t,” replies Johnny. “Come, my sweet, and I’ve something for you.” “I won’t.” “Oh! Mr. — , do, pray make Johnny come in.” “Come in, Johnny,” says the father. “I won’t.” “I tell you, come in directly, sir—do you hear?” “I won’t,” replies the urchin, taking to his heels. “A sturdy republican, sir,” says his father to me, smiling at the boy’s resolute disobedience. . . . The young were, it seemed, doing no more, nor less than was expected of them. Their parents seemed pleased at their children’s independence, even to the point of condoning their disobedience.
The Legacy of Reform—the Ideology and the Institution
Authors: Nasaw David
Published: November 2020

There was never the remotest possibility that the reformers could have succeeded in their ultimate objective of enrolling all the children of the community in their common schools. Even if the funds had been forthcoming and generous enough to build schools as grand as palaces, the poor would not have been able to send their children to them—and not because they did not understand the value of an education. As Stephen Thernstrom has written regarding the situation of the poor and working parents of Newburyport, no matter how eloquently Horace Mann might extol the benefits of a common schooling, “education for their children was simply a luxury the family could not afford.” Universal schooling—for the poor as for the prosperous— would not be attained within the reformers’ lifetimes. It was contingent on something the reformers could not produce: the acceptance of child labor regulation by the employers themselves. Without this acceptance—based on the recognition that unregulated child labor was destroying workers before they reached their productive prime—no child labor or compulsory schooling legislation could produce widespread common school enrollment. Universal common school enrollment was further dependent on other factors beyond the capacity of the reformers to effect. In the West and in rural areas of the Northeast, there could be no common schooling at all until the population was dense enough to support a school within commuting distance of each household. In the South, universal schooling was unthinkable as long as slavery was maintained. As we have seen in preceding chapters, while there appeared to be widespread agreement among Americans on the importance of schooling for their children, there was no consensus on the shape that schooling should take. There were differences of opinion over how the schools should be funded; over what form religious instruction should take; and over the qualifications for schoolmasters, the facilities for schoolhouses, the contents and objectives of school books, and the proper language of classroom instruction. In all these areas of dispute, the reformers forced their consensus on local communities not through the power of their arguments so much as through the power of their political coalitions.
New Studies for New Students
Authors: Nasaw David
Published: November 2020

The traditional high school education, by unfitting its graduates “for work with their hands,” encouraging them instead to look beyond the factory for their future employment, had become more of a problem than a solution. Still, despite its faults, it remained the only viable institutional solution to the “youth” and “worker” problems. To eject working-class youth from the institutions best situated to ease them through the perils of adolescence into the responsibilities of adulthood would serve no good purpose. The task confronting the business community and the critics of the high schools was a complex one: they wanted to bring as many “plain people” as possible into the high schools and keep them there through their teens, but in such a way that their expectations for life after graduation would not be inappropriately raised. Industrial schooling appeared to be the solution. Not only would such programs direct students towards realistic and realizable futures, but they would also attract many working class students who, the experts claimed, had been frightened away by the traditional secondary school curriculum. The masses, it was said, were not entering or remaining in the high schools because the high school curriculum had not been adjusted to their special needs. The muckrakers took great delight in calling attention to what they considered the failure of the high schools to move out of the dark ages. The secondary schools' exclusive emphasis on “culture,” it was argued, might have been appropriate to an earlier era, but was most definitely not appropriate to the modern age. “Our medieval high schools: shall we educate children for the 12th or the 20th century?” asked a Saturday Evening Post article somewhat ingenuously in 1912, the conclusion having already been reached that the schools were at least eight centuries behind the times. The critics of the public high schools, especially those from the business world, accepted without question the inability of the “masses” to proceed at the same academic rate as the “classes.” The working-class children were failing because they could not keep up with their middle-class counterparts and, in fact, were totally incapable of learning the same kinds of things.
A “Rising Tide” of Students: the Public Sector
Authors: Nasaw David
Published: November 2020

Like other patriotic institutions, higher education enlisted for service in World War II and re-enlisted for the Cold War. The universities and colleges enthusiastically provided the military and private industry with trained personnel and scientific R&D and the society-at-large with the best unemployment insurance federal money could buy. The G.I.’s, over two million of them, were welcomed into the institutions of higher education, where, as we have seen, they prospered. The schools that accepted them did as well: the money the veterans brought with them enabled the institutions to survive and remain relatively solvent through what could have been a difficult period. Though the G.I. Bill had the effect of bailing out the nation’s colleges and universities, it was originally designed not to aid education as much as to deter unemployment. In this it was most effective. Between 1945 and 1948, with G.I. enrollments close to one million, the unemployment rate stayed below 4 percent. Only in 1949, with veteran enrollment on the decline, did the rate climb back above 5 percent where it remained until the outbreak of another war. Though the postwar buying spree and the diversion of veterans from unemployment lines to college campuses had forestalled a postwar depression, the specter of massive unemployment was not entirely exorcised. The Employment Act of 1946 codified what would become a chief task of the federal government throughout the postwar period: the maintenance of unemployment levels at a rate high enough to provide employers with a reserve army to draw from but not high enough to recreate depression conditions and the possibility of social explosion. Holding unemployment down to a reasonable level through the fifties and sixties was no simple task. The corporations—through automation at home and relocation overseas—displaced workers; the federal government was expected to get them back to work or at least defuse the social discontent and potential economic catastrophe they represented. The unions took little responsibility for the shrinkage in the number of workers.
Busing the Suburbs: Milliken v. Bradley
Authors: Wilkinson J. Harvie
Published: November 2020

Brown v. Board of Education’s twentieth birthday was marked by blacks with mixed emotions. Yes, there had been conspicuous successes. Southern schools were increasingly integrated; Negroes had become more active politically; public facilities now opened to black and white alike; more federal programs attacked black poverty and illiteracy; job opportunities and income levels, though still behind those of whites, had risen appreciably; and, most important, blacks had gained in racial pride and self-respect. Yet something lacked. Few causes had ever had more federal energy thrown behind them than racial equality, yet the job remained undone. And there was uncertainty and suspicion over what the future held. “The question,” wrote Roger Wilkins in May of 1974, “is whether the momentum generated by the activities of the last 20 years . . . will almost automatically lead to racial justice in this country, as some whites seem to think, or whether, as most blacks hold, the largest and hardest job is yet to be done, and whites have quit the game before the first quarter has even ended.” Indeed, the hard part did lie ahead. Metropolitan areas, where by 1970 nearly three-quarters of all blacks lived, still had the most rigidly segregated school systems. And one-third of America’s black population remained desperately impoverished. The legal and economic gains propelling more and more blacks into middle-class ranks were themselves a mixed blessing. “The real danger,” noted black economist Robert Browne, “is that an enormous gap will develop between the blacks who have, and those who don’t. Then we’re on our way to having a permanent black underclass. That would be intolerable.” Brown’s twentieth anniversary came and went with Richard Nixon still President, and still, to blacks, distant and indifferent. His southern strategy dismissed the black vote; his domestic advisor had counseled “benign neglect” of black problems; and his lieutenants dismantled “black” federal programs only barely begun. The Departments of Justice and HEW now whistled white tunes. “By 1971,” contended Gary Orfield, “it was clear that HEW had given up its mission of bringing the nation’s public schools into compliance with constitutional requirements for desegregation.
The Argumen
Authors: Wilkinson J. Harvie
Published: November 2020

At first glance Allan Bakke seemed to be just another ordinary citizen whom landmark litigation was about to cast up from obscurity. The fortuity of other Supreme Court decisions had earlier taken Linda Brown, Clarence Earl Gideon, and Danny Escobedo and made them household names for a spell. Now the Court would do so for Allan Bakke. But, in fact, in at least one significant aspect Bakke was different. For years the focus of the Constitution had been the underside of American life. The Court had reached into shabby schools and mean alleys to succor the lowly, the despised, the dispossessed. One recalls Linda Brown, daughter of a welder on the Rock Island Railroad, standing plain-dressed before the drab edifice that was the segregated Monroe School in Topeka. Or Clarence Earl Gideon, the drunken woebegone from the Florida panhandle whose dogged requests for a lawyer became one of the most significant criminal cases of our century. The Constitution, it was thought, might help those who could not help themselves. But Allan Bakke did not exactly fit the mold. He had blue eyes, blond hair, and Norwegian ancestry, and stood just under six feet tall. Above all, Bakke was a structured, shaped-up person. He struck Dr. Theodore West of the Davis Medical School as “pleasant, mature . . . tall and strong and Teutonic in appearance . . . , a believer in personal health and fitness; he is careful about his diet and vices, runs every day and is generally interested in improving his actuarial statistics.” But another admissions officer thought him “humorless” and “zealous,” like a “character out of a Bergman film.” Bakke was never especially wealthy or advantaged. His was a storybook life of middle-class virtue. His father was a mailman, his mother a teacher. Bakke himself attended the University of Minnesota, majored in mechanical engineering, and earned just under a straight A average. To help finance his education, he joined the Naval Reserve Officers Training Corp., then fought after graduation as a Marine captain in Vietnam.
Acting, University
Authors: Elliott Carol
Published: November 2020

At the beginning of the course, I allow students to make all their own choices about a scene. Who they are. Where they are. In the early part of the course I urge them to be themselves, not to play a seventy-year-old physicist or some character outside themselves. Because they know most about themselves. They will come in with a scene, having made up imaginary circumstances. And then they’ll make choices about how they want the scene to go. I have to be careful that I help them realize the choices they’ve made. It’s so easy for a teacher to say, “God, the scene would be so much better if they had made this choice. If only he would’ve exited on that line instead of the way they ended it.” I have to remind myself that I’m not there to present a scene that I would do but to help them actualize the choices they’ve made and communicate them to an audience. Sometimes I champ at the bit. “Why don’t you do it this way?” I mean by that “my way.” If I do that, then the whole business becomes a matter of pleasing the teacher. I tell them, “If I work on a scene with you and you find me insinuating my ideas into it, just say, ‘Well, Carol, that’s not what we intended.’ “ They have to be able to do that. And then I learn, “Hey, there’s another way to do this thing.” Last week I read an unpublished essay by Peter Elbow [who was also teaching at Bread Loaf] about what he calls “The Doubting and Believing Games.” At one point he’s talking about the fact that most of the time as readers we approach in a very critical way our peers who are presenting their work for our responses in a writing class. He says that perhaps we should try to believe in the work instead of coming at it negatively. We should try to assume the view of the writer when we encounter the text.
Approaching Complexity: Thinking About Evolution
Authors: Eldredge Niles
Published: November 2020

Evolution is a complex affair. The very diversity of definitions of biological evolution illustrates the variety of ways in which we think about the subject. Perhaps still the best general description of evolution is Darwin’s “descent with modification,” simply because it simultaneously brings to mind a pattern—a result—while hinting at an understanding of process, an underlying causative mechanism. Other definitions are less broad and thus fare less well as general descriptors of this thing we call evolution. I have characterized evolution as the proposition that all organisms are descended from a single common ancestor (e.g., Eldredge 1982c, based on a suggestion from N. I. Platnick in a personal communication). This is a serviceable (and testable) construct but one that emphasizes a systematist’s concern for pattern. The utterly different and far more popular notion that evolution is “change in gene frequencies within a population” similarly emphasizes process through focusing on a completely different sort of pattern. Yet neither definition is “wrong.” The “modern synthesis” is a body of thought that grapples with the complexities of evolution. As does any good theory, the synthesis attempts to characterize the overall phenomenon and explain it in the simplest terms that seem appropriate and effective. The bewildering array of evolutionary process theories that had accumulated by the 1920s, where each biological discipline seemed bent upon establishing the primacy of its own phenomena and its own insights into processes, amounted to a net disarray for evolutionary biology. As Simpson wrote in 1944 (p. xv): Not long ago paleontologists felt that a geneticist was a person who shut himself in a room, pulled down the shades, watched small flies disporting themselves in milk bottles, and thought that he was studying nature. A pursuit so removed from the realities of life, they said, had no significance for the true biologist. On the other hand, the geneticists said that paleontology had no further contributions to make to biology, that its only point had been the completed demonstration of the truth of evolution, and that it was a subject too purely descriptive to merit the name “science.”
Public Policy Toward Private Schools: A Focus on Parental Choice
Authors: Hirschoff Mary-Michelle Upson
Published: November 2020

Not since the 1920s has our society faced so much controversy about public policy toward private elementary and secondary schools. Then, the major issue was whether private schools should be allowed to exist as alternatives to public schools. That issue was resolved in Pierce v. Society of Sisters, in which the Supreme Court upheld the right of parents to choose private schooling, and thus foreclosed a public monopoly. Today, our mixed system of private and public elementary and secondary education confronts increasing pressures for both fiscal and regulatory change. Most prominent in public debate are proposals for tuition tax credits and voucher systems and challenges to government regulation of private school teacher qualifications, curriculum, and admission practices (especially as the latter affect racial segregation). Two major public policy issues have replaced the issue of whether private schooling should exist at all: (1) To what extent should government encourage or discourage the choice of private schooling, that is, what balance between public and private schooling should government try to achieve? (2) What differences between private and public schooling should government promote or prohibit? Despite this change in emphasis, todays debates echo those of the 1920s in many respects. Just as the proponents of the 1920s laws restricting private schools feared that those schools would harm efforts to Americanize the children of immigrants, some argue today that private schools exacerbate social, economic, racial, religious, and ethnic divisions within the society and that aiding private schools will increase such undesirable effects. Now, as then, advocates of private schooling rest their arguments on the rights of parents to direct their children's education and on the benefits to society of diversity in schooling. Most dispute claims that private schools increase social stratification to any greater degree than do the public schools or that they are less effective in creating good citizens. One of the major factors that distinguishes today's debates from those of the 1920s is the greater attention paid to the impact of private schools on the quality of education.
Medical Care and Medical Education, 1825–1860
Authors: Rothstein William G.
Published: November 2020

During the early nineteenth century, medical practice became professionalized and medical treatment standardized as medical school training became more popular and medical societies and journals were organized. Dispensary and hospital care increased with the growth in urban populations. Medical students became dissatisfied with the theoretical training in medical schools and turned to private courses from individual physicians and clinical instruction at hospitals and dispensaries. By mid-century, private instruction had become almost as important as medical school training. Because little progress occurred in medical knowledge during the first half of the nineteenth century, the quality of medical care remained low, although it became more standardized due to the greater popularity of medical school training. Diagnosis continued to be unsystematic and superficial. The physical examination consisted of observing the patient’s pulse, skin color, manner of breathing, and the appearance of the urine. Physicians attributed many diseases to heredity and often attached as much credence to the patient’s emotions and surmises as the natural history of the illness. Although the invention of the stethoscope in France in 1819 led to the use of auscultation and percussion, the new diagnostic tools contributed little to medical care in the short run because more accurate diagnoses did not lead to better treatment. Few useful drugs existed in the materia medica and they were often misused. According to Dowling, the United States Pharmacopoeia of 1820 contained only 20 active drugs, including 3 specifics: quinine for malaria, mercury for syphilis, and ipecac for amebic dysentery. Alkaloid chemistry led to the isolation of morphine from opium in 1817 and quinine from cinchona bark in 1820. Morphine was prescribed with a casual indifference to its addictive properties and quinine was widely used in nonmalarial fevers, where it was ineffective and produced dangerous side effects. Strychnine, a poisonous alkaloid isolated in 1818, was popular as a tonic for decades, and colchine, another alkaloid discovered in 1819, was widely used for gout despite its harmful side effects. Purgatives and emetics remained the most widely used drugs, although mineral drugs replaced botanical ones among physicians trained in medical schools because their actions were more drastic and immediate.
The Organization of Medical Schools After 1950
Authors: Rothstein William G.
Published: November 2020

Between 1950 and 1980, state and federal funding made higher education a major component of American society in terms of the number of institutions, students, and faculty members; the range of academic and professional programs; and the capital investment and expenditures. Medical schools also grew from small, narrowly based institutions that educated undergraduate medical students to large academic medical centers that provided a wide range of educational, research, and patientcare activities. The schools changed their internal structures by replacing part-time faculty members with full-time faculty and restricting clinicians' private practices to the medical school. Their independent sources of funding and autonomy affected relations with their parent universities, affiliated health schools, and the community. The most distinctive feature of higher education after mid-century has been its greater accessibility to students. The number of degree-credit enrolled college students increased from 2.7 million in 1949 to 5.9 million in 1965, 11.2 million in 1975, and 12.4 million in 1982. Between 1950 and 1982, the proportion of the 25- to 29-year-old population who had completed four or more years of college rose from 7.7 percent to 21.7 percent, even though the number of persons in that age group increased by two-thirds. The most rapid growth in higher education occurred from the late 1950s to the mid-1970s, when total degree-credit enrollment tripled. From 1975 to the early 1980s, three-fourths of the growth has been due to part-time students. The greater accessibility of higher education has especially benefited those groups of students who had low rates of college attendance at mid-century. The number of women students increased from 0.8 million in 1949 to 6.4 million in 1981, while the number of men increased from 1.9 million to 6.0 million. Between 1950 and 1982, the proportion of blacks 25 to 29 years of age who had completed four or more years of college increased from 2.8 percent to 15.8 percent. In 1979, blacks accounted for 10.5 percent of high school graduates and 10.0 percent of college enrollees. In the same year, hispanics accounted for 4.3 percent of high school graduates and 4.2 percent of college enrollees. Changes have occurred in the academic status of many students.
Plane-Strain Problems
Authors: Kobayashi Shiro , Oh Soo-Ik , Altan Taylan
Published: November 2020

This chapter is concerned with the formulations and solutions for plane plastic flow. In plane plastic flow, velocities of all points occur in planes parallel to a certain plane, say the (x, y) plane, and are independent of the distance from that plane. The Cartesian components of the velocity vector u are ux(x, y), uy(x, y), and uz = 0. For analyzing the deformation of rigid-perfectly plastic and rate-insensitive materials, a mathematically sound slip-line field theory was established (see the books on metal forming listed in Chap. 1). The solution techniques have been well developed, and the collection of slip-line solutions now available is large. Although these slip-line solutions provide valuable insight into deformation modes and forming loads, slip-line field analysis becomes unwieldy for nonsteady-state problems where the field has to be updated as deformation proceeds to account for changes in material boundaries. Furthermore, the neglect of work-hardening, strain-rate, and temperature effects is inappropriate for certain types of problems. Many investigators, notably Oxley and his co-workers, have attempted to account for some of these effects in the construction of slip-line fields. However, by so doing, the problem becomes analytically difficult, and recourse is made to experimental determination of velocity fields, similarly to the visioplasticity method. Some of this work is summarized in Reference [2]. The applications of the finite-element method are particularly effective to the problems for which the slip-line solutions are difficult to obtain. The finite-element formulation specific to plane flow is recapitulated here.
Applications in Mineral Physics and Chemistry
Authors: Tossell John A. , Vaughan David J.
Published: November 2020

In this book we have concentrated up to this point on the experimental and theoretical methods involved in determining the electronic structure of minerals and related materials, and on the applications of these methods to major groups of compounds such as the oxides, silicates, carbonates, borates, and sulfides. It is now appropriate to turn to more general applications in the study of minerals. Three major areas are addressed in this chapter. The first concerns the general field of crystal chemistry and the extent to which calculations can be used (alongside appropriate experiments) to approach such questions as the ionic versus covalent nature of a particular bond, the understanding and prediction of crystal structure of a material of a particular composition at room temperature and pressure (or other conditions, and hence key elements of the phase relations), and the rules and principles governing the crystal structures of solids. The second concerns the behavior of minerals and related materials at high pressures, of interest because of applications to understanding the physics and chemistry of the Earth’s interior. Theoretical studies of phases at high pressure are discussed with particular reference to attempts to understand the materials that are believed to comprise the core and mantle of the Earth. The third addresses examples of application in areas of direct industrial interest, that is, to mineral materials of importance in ion-exchange and absorption, and in catalysis. These three major areas represent applications of the theoretical (and experimental) methods discussed in earlier chapters to problems of importance in mineral and crystal chemistry, in mineral physics and geophysics, and in industrial mineralogy and materials science. They are illustrative of the value of these methods, but are far from being a comprehensive account. diffraction, has led to intimate links between mineralogy and crystal and structural chemistry. Because crystal structure depends upon bonding character (“electronic” structure), it should be possible accurately to predict the crystal (or “geometric” structure) adopted by a particular composition material using quantum-mechanical methods. The extent to which this is possible is discussed below, with reference to the example of the SiO2 polymorphs.
How to Deal with Several Reservoirs
Authors: Walker James C. G.
Published: November 2020

The previous chapter showed how the reverse Euler method can be used to solve numerically an ordinary first-order linear differential equation. Most problems in geochemical dynamics involve systems of coupled equations describing related properties of the environment in a number of different reservoirs. In this chapter I shall show how such coupled systems may be treated. I consider first a steady-state situation that yields a system of coupled linear algebraic equations. Such a system can readily be solved by a method called Gaussian elimination and back substitution. I shall present a subroutine, GAUSS, that implements this method. The more interesting problems tend to be neither steady state nor linear, and the reverse Euler method can be applied to coupled systems of ordinary differential equations. As it happens, the application requires solving a system of linear algebraic equations, and so subroutine GAUSS can be put to work at once to solve a linear system that evolves in time. The solution of nonlinear systems will be taken up in the next chapter. Most simulations of environmental change involve several interacting reservoirs. In this chapter I shall explain how to apply the numerical scheme described in the previous chapter to a system of coupled equations. Figure 3-1, adapted from Broecker and Peng (1982, p. 382), is an example of a coupled system. The figure presents a simple description of the general circulation of the ocean, showing the exchange of water in Sverdrups (1 Sverdrup = 106 m3/sec) among five oceanic reservoirs and also the addition of river water to the surface reservoirs and the removal of an equal volume of water by evaporation. The problem is to calculate the steady-state concentration of dissolved phosphate in the five oceanic reservoirs, assuming that 95 percent of all the phosphate carried into each surface reservoir is consumed by plankton and carried downward in particulate form into the underlying deep reservoir. The remaining 5 percent of the incoming phosphate is carried out of the surface reservoir still in solution.
How to Solve a Nonlinear System
Authors: Walker James C. G.
Published: November 2020

In a linear system the expressions, yp, for rates of change are linear functions of the dependent variables, y. More complicated functions of y do not appear, not even products of the dependent variables like y1 * y2. But most theoretical problems in Earth system science involve nonlinearities. For example, the rate at which a chemical reaction consumes species 1 may be proportional to the product of the concentrations of species 1 and the species 2 with which it is reacting, y1 * y2. In this chapter I shall describe and solve a simple nonlinear system involving the reaction between dissolved oxygen and organic carbon in the deep sea. I shall show how the nonlinear system can be represented by a linear system, provided that changes in the dependent variables are made in sufficiently small increments. Such increments are kept small by stepping forward in time with small steps. The time step can be adjusted automatically during the calculation so as to keep the increments small enough but no smaller than necessary. Steps that are too large cause errors or even instability, and steps that are too small waste time. The representation of a nonlinear system by its linear equivalent (for small increments) calls on algebraic manipulations that can be tedious and a prolific source of mistakes in complicated systems. This algebra can be avoided, however, by letting the computer perform the equivalent manipulations numerically. I shall demonstrate how to do this, finishing the chapter with a program that can solve coupled nonlinear systems directly from the equations for the rates of change of the dependent variables, automatically adjusting the time step to small values when the rates of change are large and to large values when the rates of change are small. Figure 4-1 shows a simple model of the processes that control the oxygen balance of the deep sea. Dissolved oxygen in surface seawater equilibrates with the atmosphere. Downwelling currents carry dissolved oxygen into the deep sea, where most of it reacts (metabolically) with organic matter carried into the deep sea in the form of settling particles of biological origin.
The General Idea Behind Gödel’s Proof
Authors: Smullyan Raymond M.
Published: November 2020

In the next several chapters we will be studying incompleteness proofs for various axiomatizations of arithmetic. Gödel, 1931, carried out his original proof for axiomatic set theory, but the method is equally applicable to axiomatic number theory. The incompleteness of axiomatic number theory is actually a stronger result since it easily yields the incompleteness of axiomatic set theory. Gödel begins his memorable paper with the following startling words. . . . “The development of mathematics in the direction of greater precision has led to large areas of it being formalized, so that proofs can be carried out according to a few mechanical rules. The most comprehensive formal systems to date are, on the one hand, the Principia Mathematica of Whitehead and Russell and, on the other hand, the Zermelo-Fraenkel system of axiomatic set theory. Both systems are so extensive that all methods of proof used in mathematics today can be formalized in them—i.e. can be reduced to a few axioms and rules of inference. It would seem reasonable, therefore, to surmise that these axioms and rules of inference are sufficient to decide all mathematical questions which can be formulated in the system concerned. In what follows it will be shown that this is not the case, but rather that, in both of the cited systems, there exist relatively simple problems of the theory of ordinary whole numbers which cannot be decided on the basis of the axioms.” . . . Gödel then goes on to explain that the situation does not depend on the special nature of the two systems under consideration but holds for an extensive class of mathematical systems. Just what is this “extensive class” of mathematical systems? Various interpretations of this phrase have been given, and Gödel’s theorem has accordingly been generalized in several ways. We will consider many such generalizations in the course of this volume. Curiously enough, one of the generalizations that is most direct and most easily accessible to the general reader is also the one that appears to be the least well known.
The Incompleteness of Peano Arithmetic with Exponentiation
Authors: Smullyan Raymond M.
Published: November 2020

We shall now turn to a formal axiom system which we call Peano Arithmetic with Exponentiation and which we abbreviate “P.E.”. We take certain correct formulas which we call axioms and provide two inference rules that enable us to prove new correct formulas from correct formulas already proved. The axioms will be infinite in number, but each axiom will be of one of nineteen easily recognizable forms; these forms are called axiom schemes. It will be convenient to classify these nineteen axiom schemes into four groups (cf. discussion that follows the display of the schemes). The axioms of Groups I and II are the so-called logical axioms and constitute a neat formalization of first-order logic with identity due to Kalish and Montague [1965], which is based on an earlier system due to Tarski [1965]. The axioms of Groups III and IV are the so-called arithmetic axioms. In displaying these axiom schemes, F, G and H are any formulas, vi and vj are any variables, and t is any term. For example, the first scheme L1 means that for any formulas F and G, the formula (F ⊃ (G ⊃ F)) is to be taken as an axiom; axiom scheme L4 means that for any variable Vi and any formulas F and G, the formula . . . (∀vi (F ⊃ G) ⊃ (∀vi (F ⊃ ∀vi G) . . . is to be taken as an axiom.
The Final Transformation in Massachusetts: Market Pressures, Fiscal Crises, and Business Influences, 1971-1985
Authors: Brint Steven , Karabel Jerome
Published: November 2020

The focus of this chapter is on the shift toward predominantly vocational enrollments in the 1970s, brought on by the combined pressures of market decline, state fiscal crisis, and the political ascendance of conservative business leaders. Nevertheless, it would be misleading to suggest that contrary forces were not in evidence at least in the first few years of the 1970s. The most important of these contrary pressures was the sheer growth of the community college and university systems, which, for a time, encouraged an increase in the absolute numbers of transfers. The community colleges in Massachusetts proved to be at least as attractive in a period of economic retrenchment as they had been in better times. Low-cost, close-to-home two-year colleges were a practical alternative to more expensive higher education. Between 1970 and 1973, the community colleges’ full-time enrollment increased by over one-third, and the other two tiers grew slightly less rapidly. As the system became more vocational in the late 1960s, it also grew. Because of this growth, the absolute number of community college students who transferred to four-year colleges increased, even though the transfer enrollment rates were slowly declining. The number of community college students transferring to the University at Massachusetts at Amherst, for example, increased from just 80 in 1964, when only seven community college campuses were open, to 425 in 1970 and then to 950 in 1972, when twelve campuses were operating at full capacity. In 1973, at the peak of transfer enrollments, 1,165 public two-year college students enrolled at the University of Massachusetts; 680 enrolled in the state colleges; and 525 enrolled in four-year private colleges in Massachusetts.2 Although never more than a small fraction of total community college enrollments, transfer rates did rise dramatically, from approximately 12.5 percent of the sophomore class in 1964 (a rate congenial to the original planners) to nearly 30 percent of the sophomore class in 1973 (Beales 1974). The nationwide decline in the market for college-educated labor in the early 1970s hit Massachusetts with slightly greater force than in other states, being reinforced by a recession in the newly emerging high-technology belt around Boston that was related to the winding down of the war in Southeast Asia.
Arthropoda
Authors: Lowenstam Heinz A. , Weiner Stephen
Published: November 2020

The arthropods are distinguished by having segmented bodies and appendages, as well as hardened external skeletons. Growth is achieved by shedding the exoskeleton and then regenerating a new and larger one. The hardening of the exoskeleton usually occurs by chemical cross-linking (sclerotization) of the macromolecular constituents, mostly proteins and the polysaccharide, α-chitin. The major exception is the class Crustacea. The members of this group harden their skeleton not only by sclerotization, but also by the addition of inorganic minerals. After each molting, the new exoskeleton is remineralized. The result is that many Crustacea, particularly those that live in freshwater or on land where the availability of calcium is limited, have evolved novel and diverse temporary storage sites for mineral (reviewed by Greenaway 1985). From the perspective of biomineralization processes, this adaptation is certainly one of the “highlights” of the Arthropod phylum. Interestingly one taxonomic order within the Crustacea, the Cirripedia or barnacles, does not moult their heavily mineralized cuticles, even though their “organic” exoskeleton does go through periodic molting cycles (Darwin 1854). Table 7.1 lists many of the known reports of biomineralization processes in the Arthropoda. The table is already impressively long. However, as this phylum is by far the largest in the animal kingdom, we have no doubt whatsoever that the true extent of mineralization processes in the Arthropoda is far from having been ascertained. In the insects alone nearly half a million species have been described, and our list comprises just a few documented cases of insects that mineralize. Interestingly, the list of minerals formed by insects includes a number of so-called “organic minerals,” for example, uric acid, crystalline wax, and long chain paraffins. We strongly suspect that many more “organic minerals” have yet to be discovered among the insects.
The World Transformed: A Golden Age for American Universities, 1945–1970
Authors: Freeland Richard M.
Published: November 2020

In the years following World War II, academic leaders in Massachusetts participated in a national debate about the social role of higher education in the era that lay ahead. They also experienced the beginnings of a period of expansion for universities that would continue, more or less uninterrupted, for twenty-five years. Change in this postwar golden age involved an ongoing interaction between ideas and opportunities: the first concerning the public purposes of higher education; the second promising glory for institutions and advancement for academic interest groups. For most of the period, the dominant view—inside and outside of higher education—was that expansion was improving the academy as well as the country, but the turmoil of the late 1960s raised fundamental doubts about the character of postwar change. Although World War II entailed difficulties for universities, their extensive involvement in the military effort stirred a new awareness of the social importance of academic work. This habit of thought extended into the postwar period, as educators, exhilarated by wartime patriotism, looked for new ways to contribute to social problem solving. As they did so, they exhibited a further effect of their recent experience: a tendency to focus on national concerns—as distinct from regional or local ones—far more intensively than they had done before 1940. The country's agenda was long. The human costs of the war, and the even more-frightening possibility of atomic conflict, made the importance of maintaining peace evident. Europe had precipitated two wars in a generation and now lay in ruins. The United States, suddenly the preeminent power of the globe, would have to pioneer in shaping a stable world order. In some, the nation's new international prominence aroused a sense of urgency about discrimination and inequality at home. More broadly, world leadership implied a need to maintain military and economic power and the technological vitality on which they depended. Many educators believed they had important roles to play in all these contexts—through training leaders, forming attitudes, and advancing knowledge. As one college president put it: “Events... have shaken the complacency of many university communities and compelled educators to... make [their] maximum contribution to a decent, well-ordered, free and peaceful society.”