bluuebunny/crossref_metadata_2025 huggingface dataset:
The Ecological Foundations of Biodiversity Protection
Authors: MacKinnon Kathy
Published: November 2020

Two thirds of all known species occur in tropical regions, and probably half of all species are confined to tropical rain forests—yet these rain forests are among the most threatened of all natural habitats. Throughout the tropics, rain forests are being destroyed at an alarming rate. It has been estimated that, worldwide, approximately 170,000 square kilometers of rain forests—an area almost as great as Cambodia—are being lost every year (FAO, 1990). Few tropical countries retain more than half of their natural forest cover, and even those that do are witnessing rapid habitat conversion. Figure 3-1 illustrates the decline of primary forest cover on Sumatra during the past 60 years, a picture that is duplicated over much of tropical Asia. The Indonesian archipelago, as a whole, loses at least 9,000 square kilometers of forest each year to logging, land conversion, and shifting agriculture (MoF/FAO, 1991). In some years, the figure is even higher. In 1982 and 1983, for example, severe drought and fires (often deliberately started) damaged 36,000 square kilometers of forest—an area the size of Belgium—in East Kalimantan in Indonesian Borneo (Lennertz and Panzer, 1983) and another 10,000 square kilometers in Sabah (Malingreau et al., 1985). Destruction of tropical habitats leads to the irreversible loss of biological diversity and genetic resources. Conservation of biodiversity will require a concerted effort to provide adequate and effective protection of tropical forests and their native species. The best, easiest, and least expensive way to achieve this goal is to establish networks of protected rain forest areas for in situ conservation of gene pools, species, and ecosystems. Forest destruction is proceeding so fast that this decade is probably the last chance to protect extensive areas of tropical forests; indeed, for some countries it is already too late. While this chapter focuses primarily on tropical Asia, many of the lessons and recommendations apply equally well to the rain forests of Africa and Central and South America. The question of how much protected habitat is enough has long been debated by conservationists and other scientists.
Amphibians and Reptiles
Authors: Alan Pounds J.
Published: November 2020

Anyone who stood on the bridge over the Río Guacimal at Monteverde on a wet-season night in the early 1980s would understand Archie Carr’s sentiments. Nearly 300 male Fleischmann’s Glass Frogs (Hyalinobatrachium fleischmanni) defended territories along a 120-m section of the stream, and their loud, incessant “peeps” filled the air. In the late 1980s, however, this chorus all but fell silent as the number of glass frogs plummeted. The population has not recovered. In 1998, only a single male could be heard from the bridge. The dramatic reduction in glass frogs was part of a larger decline of Monteverde’s amphibians. A sudden crash of populations in 1987 affected species throughout the area and led to the disappearance of many (Pounds 1990, 1991a, 1997, Crump et al. 1992, Pounds and Crump 1994, Pounds and Fogden 1996, Pounds et al. 1997). The disappearance that has drawn the most attention, however, is that of the Golden Toad (Bufo periglenes). This species, known only from elfin cloud forest high on the ridgetops at Monteverde, is famous for its striking appearance and the colorful spectacle of its breeding congregations (Savage 1966, Jacobson 1983, Fogden and Fogden 1984, Jacobson and Vandenberg 1991; see Savage, “Discovery of the Golden Toad,”. Because the Golden Toad had been locally abundant in seemingly undisturbed habitats for at least 17 consecutive years, its sudden disappearance caused great alarm and dismay (Pounds et al. 1997). Interest in this case has intensified with the suggestion that it is part of a global pattern (Barinaga 1990, Blaustein and Wake 1990, 1995, Phillips 1990, 1994, Wyman 1990, Wake 1991, Wake and Morowitz 1991, Sarkar 1996; see Pounds, “Monteverde Salamanders,”). Many similar declines and disappearances have been reported for highland areas of other continents (Corn and Fogleman 1984, Heyer et al. 1988, Osborne 1989, Weygoldt 1989, Czechura and Ingram 1990, La Marca and Reinthaler 1991, Carey 1993, Fellers and Drost 1993, Kagarise Sherman and Morton 1993, Drost and Fellers 1996, Laurance et al.
Mammals
Authors: Timm Robert M. , LaVal Richard K.
Published: November 2020

Costa Rica is one of the most biotically diverse countries on earth, with 4% of known terrestrial plant and animal species in only 0.04% of the world’s land surface. The country’s mammal fauna is equally diverse, with more than 207 species (4.8% of the world’s 4629 species) in an area of 51,022 km2. The majority of the world’s mammal species and Monteverde’s fauna are small (< 0.5 kg), nocturnal, and secretive. We know considerably less about most neotropical mammals and other vertebrates than we do about birds, which are more easily observed and communicate with sounds audible to humans. Although certain species of mammals have been studied in Costa Rica (Janzen 1983a, Timm 1994, Vaughan and Rodríguez 1994), and Monteverde is one of the best-known regions of the country biologically, there has been little work on the ecology, distribution, abundance, altitudinal zonation, systematic relationships, and biogeography of most mammals. Deforestation and other human disturbances have had a significant impact on the native mammals of the region; knowledge of Monteverde’s mammals is vital to understand how habitat changes affect tropical montane mammals. In this chapter, we provide an overview of the mammal fauna of the Monteverde area. We discuss the biology and abundance of some of the area’s species, document how these are changing, and explore conservation issues. Most of the research on mammals at Monteverde has centered on bats or rodents, the two most diverse groups. Much of our knowledge of other species consists of isolated observations. We augment published reports with unpublished observations made by ourselves and colleagues. We also examined most of the Monteverde mammal specimens in museum collections to verify species identifications and to understand better their systematics, ecology, and distribution. We integrate this information into a list of the mammals that occur in the region, document their occurrence in each life zone, and estimate their overall abundance.
Turing Patterns
Authors: Epstein Irving R. , Pojman John A.
Published: November 2020

In the first chapter of this book, we noted the “dark age” of nearly forty years separating the work of Bray and Lotka in the early 1920s and the discovery of the BZ reaction in the late 1950s. Remarkably, the history of nonlinear chemical dynamics contains another gap of almost the same length. In 1952, the British mathematician Alan Turing wrote a paper in which he suggested that chemical reactions with appropriate nonlinear kinetics coupled to diffusion could lead to the formation of stationary patterns of the type encountered in living organisms. It took until 1990 for the first conclusive experimental evidence of Turing patterns to appear (Castets et al., 1990). Turing was a formidable figure (Hodges, 1983). He was responsible for much of the fundamental work that underlies the formal theory of computation, and the notion of a “Turing machine” is essential for anyone who wishes to understand computing and computers. During World War II, Turing was a key figure in the successful effort to break the Axis “Enigma” code, an accomplishment that almost certainly saved many lives and shortened the war in Europe. His 1952 paper, entitled “The Chemical Basis of Morphogenesis” was his only published venture into chemistry, but its impact has been enormous. Recently, this classic paper has been reprinted along with some of Turing's unpublished notes on the origins of phyllotaxis, the arrangement of leaves on the stems of plants (Saunders, 1992). In this chapter, we shall describe the nature of Turing patterns and some of the systems in which they may play a role, explore why they have been so elusive, examine the experimental systems in which they have been demonstrated, and consider other systems and other methods for generating them. Much of our discussion will focus on the chlorite-iodide-malonic acid (CIMA) reaction in which the patterns were first seen. In the study of Turing patterns, the CIMA system and its relatives play much the same role today that the BZ reaction played during the 1960s and 1970s in the study of chemical oscillation.
Pressure and Cold Denaturation of Proteins, Protein-DNA Complexes, and Viruses
Authors: Silva Jerson L. , Da Poian Andrea T.
Published: November 2020

The application of hydrostatic pressure provides a means of appraising interprotein and intraprotein interactions isothermally and makes it possible to sample partially folded conformations. A number of proteins exhibit cold denaturation and cold dissociation. We have used the combined effects of pressure and low temperature to promote dissociation or denaturation of single-chain proteins, oligomers, protein-DNA complexes, and viruses. In this article, we summarize results that have biological relevance. The dissociation and denaturation of the hexameric protein, allophycocyanin, are accomplished only when the temperature is decreased to —10 °C, indicating the entropic character of the folding and association reaction. The folding and dimerization of Arc repressor in the temperature range of 0—20 °C is also favored by a large positive entropy that counteracts an unfavorable positive enthalpy. On binding operator DNA, Arc repressor becomes extremely stable against denaturation. However, the Arc repressor-operator DNA complex is cold denatured at subzero temperatures under pressure. The entropy increases greatly when Arc repressor binds tightly to its operator sequence but not to a nonspecific sequence. The dissociation and denaturation of icosahedral viruses by pressure and low temperature also have been studied. The procapsid shells of bacteriophage P22 only dissociate by pressure at temperatures below 0 °C. On the other hand, the monomeric coat protein is very unstable toward pressure. Cowpea mosaic virus (CPMV) dissociates only in the presence of 1.0 M urea, at 2.5 kbar when the temperature is decreased to — 15°C. At temperatures close to — 20 °C, partial denaturation is obtained even in the absence of urea. The assembly of CPMV is related to large and positive variations or enthalpy and entropy, making the assembly of ribonucleoprotein components an entropy-driven process. We conclude that protein folding, protein association, and protein-DNA recognition seem to need positive entropy to occur. We are facing a puzzle in which a final, apparently more ordered state is achieved, a state that paradoxically has more entropy. In the last 20 years, several studies have described the cold denaturation of proteins (Brandts, 1964; Sturtevant, 1977; Privalov et al., 1986; Griko et al., 1988; Chen & Schellman, 1989, and as reviewed in Privalov, 1990). However, unlike thermal denaturation, cold denaturation is not well understood.
Introduction
Authors: Yu T. R.
Published: November 2020

The constitution and properties of soils have their macroscopic and microscopic aspects. Macroscopically, the profile of a soil consists of several horizons, each containing numerous aggregates and blocks of soil particles of different sizes. These structures are visible to the naked eye. Microscopically, a soil is composed of many kinds of minerals and organic matter interlinked in a complex manner. In addition, a soil is always inhabited by numerous microorganisms which can be observed by modern scientific instruments. To study these various aspects, several branches of soil science, such as soil geography, soil mineralogy, and soil microbiology, have been developed. If examined on a more minute scale, it can be found that most of the chemical reactions in a soil occur at the interface between soil colloidal surface and solution or in the solution adjacent to this interface. This is because these colloidal surfaces carry negative as well as positive charges, thus reacting with ions, protons, and electrons of the solution. The presence of surface charge is the basic cause of the fertility of a soil and is also the principal criterion that distinguishes soil from pure sand. The chief objective of soil chemical research is to deal with the interactions among charged particles (colloids, ions, protons, electrons) and their chemical consequences in soils. As depicted in Fig. 1.1, these charged particles are closely interrelated. The surface charge of soil colloids is the basic reason that a soil possesses a series of chemical properties. At present, considerable knowledge has been accumulated about the permanent charge of soils. On the other hand, our understanding is still at an early stage about the mechanisms and the affecting factors of variable charge. The quantity of surface charge determines the amount of ions that a soil can adsorb, whereas the surface charge density is the determining factor of adsorbing strength for these ions. Because of the complexities in the composition of soils, the distribution of positive and negative charges is uneven on the surface of soil colloidal particles. Insight into the origin and the distribution of these charges should contribute to a sound foundation of the surface chemistry of soils.
Reactions with Hydrogen Ions
Authors: Zhang F. S. , Yu T. R.
Published: November 2020

Hydrogen ion is one kind of cation which possesses many properties common to all cations. Hydrogen ion also has its own characteristic features which are of particular significance for variable charge soils. The interactions between hydrogen ions and the surface of soil particles is the basic cause of the variability of both positive and negative surface charges of variable charge soils. The quantity of hydrogen ions in soils determines the acidity of the soil while the acidity of variable charge soils is among the strongest in all the soils. This strong acidity of variable charge soils affects many other chemical properties of the soil. In this chapter, the basic properties of hydrogen ions will be briefly discussed. Then, the products and the kinetics of the interaction between hydrogen ions and variable charge soils will be treated. The dissociation of hydrogen ions from the surface of soil particles has already been mentioned in Chapter 2. After the dissociation of an electron, a hydrogen atom becomes a proton (H+ ion). The ionization energy of hydrogen atoms is 1310 kj mol-1, whereas those of alkali metals, Li, Na, K, and Cs, are 519, 494, 419 and 377 kj mol-1, respectively. This difference in the ionization energy between hydrogen and alkali metals indicates that protons have a particularly strong affinity for electrons. Therefore, protons are apt to form a covalent bond with other atoms by sharing a pair of electrons, or to form a hydrogen bond. Because of the absence of an electronic shell, a proton has a diameter of the order of 10-13 cm, while other ions with electronic shells generally have a diameter of the order of 10-8 cm. Because a proton is so small, it is quite accessible to its neighboring ions and molecules. Therefore, there is very little steric hindrance when protons participate in chemical reactions. The above-mentioned features of proton are the basis for its particular properties. Free proton in solution is extremely unstable because it is very active. In an aqueous solution it will react with water molecules to form a hydrated proton, H3O+.
Constructing Ourselves: The Beginning of an Evolving Philosophy
Authors: Johnston Marilyn
Published: November 2020

From the beginning of my experience as a teacher in the OC and its private school precursor, the Thoreau School, I was intrigued with the role that an evolving philosophy played in the development and sustenance of the program. The debating and refining of the philosophy stands in sharp contrast to my experience in educational settings before and after my involvement in this school. In other teaching contexts in which I have participated, both in elementary schools and at the university level, philosophies are seldom discussed or made explicit. Philosophical positions are sometimes imposed, other times taken for granted; seldom are they debated. Even less often are philosophical discussions used as the central activity for constructing the program. In the beginning of the program, especially during the Thoreau School years (the private school endeavor that began in 1971 and led into the OC public school in 1977), our very survival depended on articulating a philosophy that would bind us together as a group and entice others to join us. Without a clear philosophy to guide us, we had no mission or purpose. As I worked with the program over 15 years, as both a teacher and parent, I was convinced that a continuing discussion of our philosophical roots and putting this philosophy into practice was our lifeline. I worry about the program over the long term if it loses this sense of debate and introspection. The process of clarifying the philosophy not only developed shared norms and practices and articulated these to others, it was also how we educated ourselves. I was hired by the instigating group of parents to be the first teacher at Thoreau School. The first year I had 21 children from 14 families in a kindergarten-to-sixth-grade classroom, from age 5 to 12 years. The basic characteristics of this first school have survived past the Thoreau School years, over the more than 20 years of the OC program's existence as a public school. This was to be a parent co-operative program that encouraged children, parents, and teachers to collaboratively design the program and the curriculum.
Seeing the Big Picture
Authors: Bartlet Leslee
Published: November 2020

When someone walks into our community of learners for the first time, his or her initial impression is often one of chaos. How can you tell what anyone is doing? Why are those children under the table? Who is watching the ones in the hall? The range of activity may include a lone reader curled high in a loft, an animated group involved in a dice game, or several students in elaborate costume refining the dialogue of their latest play. A visitor may also be hard put to identify the teacher among the four or five adults scattered throughout the room. That suited gentleman on his knees by the computers? The guy in jeans and T-shirt at a table, laughing with five children over a storybook? The woman in a flowing skirt sitting cross-legged on the floor, surrounded by young mathematicians intently measuring their row of brightly colored cubes? All look equally engaged with the students—no one is sitting at the desk in the corner! If the visitor pauses more than a moment or two, however, at least one of the adults (and, most likely, several children) will excuse him- or herself from the group and approach the newcomer: While from the outside it may seem impossible to detect much of anything, once you're in the know—on the inside—the slightest variation in activity is immediately apparent. All well-run classrooms, regardless of educational philosophy, have a highly developed internal structure that is invisible to the uninitiated, consisting of the philosophy and practices that help participants determine expectations for themselves and others. These are the “cultural” guidelines—surrounding subject matter, group discussions, playtime, and so on—that allow students to settle into a familiar pattern and free them to explore their learning. This internal structure determines how children learn with their teacher, each other, the parents, and the materials they use in the classroom. It's the structure that sets up boundaries for communication, outlining when and how students relate to one another during the day.
Setting the Scene: Coordinating a Classroom Community
Authors: Polson Donene
Published: November 2020

Throughout my years at the OC, first as a parent and then also as a teacher, I have given a lot of thought to the structure and coordination of the classroom, which supports parents, children, and teachers in creating a community of learners. I had enrolled my children in the OC because I liked the idea of students, teachers, and parents all working together as a community to help children learn. After spending a great deal of time as a co-oper, I returned to the university to earn a degree in elementary education and then added the role of teacher to my established parent role in the OC. In a community of learners, a tremendous amount of work is done behind the scenes—extensive coordination, planning, and structure allow the daily learning and activities to flow smoothly. It is like a ballet, where the performers move so gracefully, flowing to their positions and cooperating with such beauty that it looks deceptively simple. Yet we know it is preparation, planning, refining, and cooperation that allow the production to run so smoothly. In the OC, the coordination is based on backstage efforts among the adults of each classroom, teamwork among children and adults, and daily and weekly routines around which children’s, co-opers’, and teachers’ activities are organized. Although the teacher plays a unique role, coordination and planning are shared among all participants and extend beyond individual classrooms to the OC program as a whole. . . . Backstage Coordinating among Adults in the Classroom . . . A key support for coordinating the classroom community is the collaboration among adults. Before the school year begins, parents and the teacher hold a meeting at a family’s home to prepare for the upcoming year, getting acquainted and establishing weekly co-oper schedules and curriculum areas for the parents’ contributions to the classroom teaching. As teacher, I figure out how to coordinate the co-opers’ schedules, interests, and talents from their work, hobbies, and outside activities to create a balanced weekly structure that becomes the framework for the children’s activities.
Creating Curriculum with Children
Authors: Turkanis Carolyn Goodman
Published: November 2020

Children are natural learners, curious and inquisitive, wondering why and who and how. They thrive in an environment that allows curriculum to emerge naturally, with support from other children, co-oping parents, and teachers, around their needs and interests. They are quick to express opinions, offer suggestions, and invent projects. They are an incredible natural resource, and in a community of learners, they contribute to meaningful, exciting curriculum. In a community of learners, everyone has a part to play in supporting the learning process. Children help plan and develop curriculum and are expected to be active participants and responsible learners. Parents support projects and activities with ideas and guest speakers; they teach and present curriculum. The teacher supports both children and parents in their planning, organizes and facilitates all the learning involved, and is ultimately accountable for curriculum development and content. Each role is valuable and part of the whole—more than the sum of the parts. Curriculum can be built by the community together, making use of children’s interests and experience as a key impetus. Such curriculum builds on individual and collective interests to weave together instructional interactions that support and inspire learning by: . . . • Seizing the moment to build on interesting ideas that emerge in classroom discussion . . . . . . • Recognizing that children have their own learning agendas that can provide motivation and the “way in” to learning about all kinds of other curriculum areas . . . . . . • Supporting units of study that often emerge as a group process, as people become interested in each others’ interests and build on each others’ expertise . . . . . . • Using resources of all kinds (with little reliance on textbooks) . . . After exploring these points, I will discuss how the classroom structure and the teacher help create such an emerging curriculum, and the question of what the children learn. Curriculum is all around us, just waiting to happen. This is frequently referred to as “teaching to the moment,” or “seizing the moment.”
Kindergarten, Again
Authors: Bartlett Howard
Published: November 2020

Just because I was going back to kindergarten at the age of 42 was no reason to be nervous. After all, I had breezed through kindergarten 37 years earlier, or so my mother assured me with a warm smile as she leaned in the bathroom doorway watching me shave. “So you’re going co-oping,” my mother said. I stopped my razor at the end of its dull and somewhat painful passage up the length of my neck. I replied with a tentative yes. “What does a co-oper do?” My newly widowed mother had moved out of New England during the summer to help with the raising of our son, Bartie. She was a Yankee down to the depths of her crusty soul, suspicious, sure of what she knew, forever ready to take on the world with a mixture of honesty and determination that left little room for doubt that she would do her best to stick around forever to ensure that her own would have a safe passage through the world. “Co-opers help out in the classroom,” I replied, rinsing my razor under a brief stream of water. I knew that my reply was too short. My mother already should have known. My wife, Leslee, had been teaching in the OC for 10 years. I had written many letters home explaining the philosophy of placing the child at the center of the learning experience. “Help out? How do you help out?” Mother shifted restlessly in the doorway. I knew her well. She was concerned that this unusual school might not be good enough for her grandson. Questions she already knew the answers to were her own way of being nervous. Like all the first-time parents, she was letting a piece of herself go that morning. A school with no desks, no grades: How could she be sure that her grandson would get the basics? The idea of communication and understanding before competition sounds good. Childhood is a journey, not a race. That sounded good, too. But still... “We come up with learning centers or activities, or we help students problem solve when there is a dispute. Or we might go through stories children have just written and help them ‘book spell’ the words they spelled their own way.
Constraints and Opportunities
Authors: Yarmolinsky Adam
Published: November 2020

Liberal education has always proved a challenge to deliver systematically, if only because by its very nature it is difficult to specify. In the United States, institutions that seek to offer liberal education on the threshold of a new century operate under new or, at least, significantly more chafing constraints. This article examines some of these constraints and suggests ways in which they can be relieved or accommodated. The principle constraints discussed here are those of shrinking material resources, expanding and accelerating expectations, and increasing heterogeneity across the student body. In the face of these constraints, academic institutions from small liberal arts colleges to large research universities are no better able than other institutions to adapt themselves to changing circumstances—and perhaps a little bit less so. Resource constraints stem from internal and external causes. The internal causes, I will argue, are the result of an economic anomaly. It is not possible for the direct delivery of liberal education to become significantly more efficient in the same way that other economic processes do, at least in part because liberal education is not something that can be "delivered": thus, there is a productivity lag behind other sectors in the economy. The institution cannot fully compensate for this lag by making improvements in the efficiency of other activities (e.g., computing or building maintenance). The external causes, in the public sector, arise from the insistent demands for other uses of public funds, combined with continued popular resistance to tax levels comparable to those of other industrial democracies. In the private sector, the external cause is the declining capacity (or willingness) of families and individual payers to meet even a partial share of the cost of liberal education. Other constraints result from expanding and accelerating expectations as students and their families demand that they be prepared for specific jobs or get a leg up on specific postgraduate professional training. In a sense this is the other side of the coin of employers' broader demand for higher education. As the proportion of jobs requiring undergraduate and graduate degrees has increased, the vocational aspect of higher education has increased accordingly.
World War II and Institutional Shifts
Authors: Gleason Philip
Published: November 2020

World War II set the stage for an era of tremendous growth in American higher education, growth in which the Catholic sector shared fully. Between 1940 and 1960 the number of Catholic colleges and universities increased by one-fifth (from 193 to 231), faculties grew by about 85 percent (from 13,142 to 24,255), and enrollments almost doubled that percentage, zooming from just under 162,000 to just over 426,000, an increase of 164 percent. Sheer growth was thus the most basic of the institutional developments that took place in this era, but it presented itself more as a series of crises than as a process of continuous accretion. The first crisis, brought on by the wartime draft and the attraction of highpaying jobs in defense industries, imperiled the very existence of the colleges by depleting their pool of potential students. Then came the overwhelming surge of postwar veterans that almost swamped the system. And just as educators were regaining their balance from that onslaught, the outbreak of the Korean War threatened to start the cycle all over again. Korea proved to be a mere dimple compared with World War II, but steady growth did not really begin until 1953.
The End of an Era
Authors: Gleason Philip
Published: November 2020

The coming together of the racial crisis, bitter internal divisions over the Vietnam War, campus upheavals, political radicalism associated with the New Left, the growth of the counterculture, and the emergence of new forms of feminism made the 1960s an epoch of revolutionary change for all Americans. But for American Catholics the profound religious reorientation associated with the Second Vatican Council multiplied the disruptive effect of all the other forces of change. This clashing of the tectonic plates of culture produced nothing less than a spiritual earthquake in the American church. Although the dust has still not fully settled, it was clear from an early date that the old ideological structure of Catholic higher education, which was already under severe strain, had been swept away entirely. As institutions, most Catholic colleges and universities weathered the storm. But institutional survival in the midst of ideological collapse left them uncertain of their identity. That situation still prevails. To explore it fully would require another book. Our task now is to review the emergence of the problem, sketch its general outlines, and point out why it marks the end of an era in the history of Catholic higher education. For a number of reasons, freedom became the central theme in American Catholic higher education in the early 1960s. As the most basic of American values, it was, of course, immensely attractive to the socially assimilated generation of younger Catholics for whom John F. Kennedy’s election and Pope John XXIII’s aggiornamento vindicated the hopes of the earlier Americanists, whose travails Catholic historians had so recently explored. Moreover, the contemporaneous demand by African Americans for “Freedom Now” linked freedom to the religious idealism of the Reverend Martin Luther King, Jr.’s non-violent crusade for civil rights. Freedom was, in addition, the polar opposite of the rigidity, formalism, and authoritarianism that had become so distasteful to American Catholic intellectuals; by contrast, it meshed beautifully with their growing insistence on the importance of individual subjectivity.
City Walls
Authors: Sperber Daniel
Published: November 2020

References to a variety of topics relating to city walls appear not infrequently in Rabbinic sources. This is by no means surprising, since quite a number of Palestinian Roman (and Byzantine) cities were walled. Such was the case with Caesarea, Beit Shean, Jerusalem, Gaza, Ashkelon, Akko, Neopolis, Tiberias, Emmaus, Beit Guvrin, and Ashdod. The importance attributed to such walls is clearly expressed in the following parable in Mechilta Yitro, 5, ed. Horowitz-Rabin p. 219: . . .A certain person entered the city. He said to them (the citizens): I will rule over you. They said to him: Have you done anything for our good that you should rule over us? (i.e., that we should accept you as our ruler)? What did he do? He built them a wall, and brought them water [into the city] (See discussion below). . . . Some of these walled cities are portrayed in the mosaic Medva (Medeba) map of the late sixth century C.E. We shall begin our survey with what is known about financing the building and upkeep of city walls. We ended the last chapter with a reference to the discussion in Baba Batra on walls and their upkeep.
Multivariate AR Processes
Authors: Polyak Ilya
Published: November 2020

This chapter is devoted to different computational aspects of multivariate modeling. An algorithm for fitting such models with sequential increasing of the order is given. Several examples of approximation of multiple climatological time series by first-order AR models are considered. It is emphasized that such modeling can be used not only for forecasting, but also for the analysis of the parameter matrix as a matrix of the interactions and feedbacks of the observed processes. Some problems in identifying stochastic climate models are also discussed. It is shown that formulation of climatology problems within the strict frameworks of fundamental theory will facilitate natural progress along with the development of these methods.
Reconstructing the Crime
Authors: Verschuur Gerrit L.
Published: November 2020

Just what happened to the dinosaurs? In the mind’s eye, travel back to the Cretaceous period, 65 million years ago. First, land in a region of the world that will someday be called Oklahoma. You are in the era of dinosaurs, although there are no longer as many species about, worldwide, as there were ten million or so years before. In all, 23 species roam their individual parts of the planet. It is their lack of spatial diversity that will make them vulnerable to the catastrophe that is about to befall the earth. So imagine you are there, together with triceratops, stegosaurus, velociraptors, and tyrannosaurus rex. Mostly they live off the land, and some of them live off each other. On this day none of the animals on earth can possibly have any awareness that they are about to disappear. Such a luxury will only be granted to a conscious species that has learned to explore the universe. For those who survive the initial impact explosion and its immediate consequences, the coming months will mark a terrible example of one of Cuvier’s “brief periods of terror.” In rapid succession, all life will be subject to a holocaust of staggering proportion, horrendous blast waves, searing winds, showers of molten matter from the sky, earthquakes, a terrible darkness that will cut out sunlight for a year, and freezing weather that will last a decade. The ozone layer will be destroyed, and acid rain will make life intolerable for species that survived the first few months after the impact. You are there and you have been observing an odd phenomenon in the sky. For thousands of years a great comet has loomed, repeatedly lighting up the heavens with its glorious tail and then fading away to reappear a few years later. Long ago it was seen to break into fragments, each of which was a spectacular sight in its own right. Sometimes one of those fragments seemed to loom ever so close to the earth. For thousands of years, spectacular meteor showers have been seen whenever the earth passed through the tail of one of those comets, and sometimes dust drifted down into the atmosphere and disturbed the climate.
Words, The Magic Kingdom
Authors: Wiener Harvey S.
Published: November 2020

When Alice faces the extraordinary Wonderland notions of saying what you mean and meaning what you say, she confronts language's great potential and disappointment. Words should, but do not always, mean what they say; and we who use them do not always produce what we mean. If only we could point to a direct correspondence between each word and only one exact meaning! Reading would simplify in a flash. Ah, but what we might gain in exactness and dazzling clarity, surely we would lose in flexibility, nuance, suggestiveness, and contextual richness. It's good that words have such a wide range of meanings and uses; as such they enrich our capabilities as earths highest life forms and its most competent communicators. Knowing the possibilities of language, understanding the many qualities of words and how our language depends on them, can enhance your child's attempts to determine meaning from print. In the long climb up the mountain to word mastery, a major feature of language that you can help your youngster understand is that words often mean more than they say. Certainly, words have denotative meanings. That is, words have exact definitions that you could check easily in a dictionary. A jeep is a heavy-duty, four-wheeled vehicle. A communist is someone who believes in a social and political system characterized by common ownership and labor organized for the common good. A frigate is a high-speed, medium-sized war vessel of the 17th, 18th, and 19th centuries. Yet each of these words has connotative meanings as well. What a word connotes is what it suggests or implies beyond its actual meaning—including the associations and feelings aroused by the word. A jeep is more than a motor vehicle with four-wheel drive; its connection with the military and rugged outdoor life suggests certain associations—rough riding, speed, even danger perhaps. Your son or daughter might like to ride to school in a jeep just for the fun of it, but you'd have 'been puzzled (to say nothing of your parents!) if your date for the senior prom honked the jeep horn outside your front door when he arrived to pick you up.
Indirect Factors Contributing to Extinction
Authors: Moll Don , Moll Edward O.
Published: November 2020

Damming and sand mining are examples of factors that indirectly damage or destroy populations of river turtles. Direct factors such as human exploitation are typically more obvious causes of population decline and often serve as stimuli to incite conservation action by a concerned public or government. While direct factors typically kill animals outright or at least remove them from the gene pool, indirect factors can surreptitiously reduce their chances for survival by altering habitat or reducing food supplies. As such, they may decimate a population before it becomes obvious that something is wrong. Though less conspicuous than the direct causes, indirect factors are at least of equal importance in determining the ultimate survival of a species. Table 6.1 summarizes the types of indirect factors affecting selected species. Two important types of indirect factors, habitat alteration and species introduction, are discussed below. Habitat alteration implies any change in an animal’s environment, but herein we will consider human or anthropogenic alterations. Anthropogenic habitat changes are not necessarily harmful to every type of turtle. Riverine specialists are more vulnerable to such changes than are eurytopic generalists that occupy a variety of lotic and lentic habitats. Generalists are by their nature adaptable and thus are less likely to be harmed by changing conditions. A study by D. Moll (1980) on the Illinois River illustrates this principle well. The original environment of the Illinois River has been greatly altered as a result of clearing and draining land for agriculture, dumping of municipal sewage (particularly by the Chicago Sanitary District), and the construction of a series of locks and dams by the Corps of engineers to facilitate barge traffic. Moll found that while these alterations had reduced or eliminated populations of Blanding’s turtles, yellow mud turtles and smooth softshells, generalist species such as the common slider, false map turtles, spiny softshells and common snapping turtles were thriving in the altered environment (see also Mills et al, 1966; Bellrose et al., 1977). Similarly, Anderson (1965) reported that commercial fishermen of the Mississippi and Missouri Rivers noted increases in softshells (spiny?) and snappers in areas having moderate sewage pollution.
Peircean Graphs for Prepositional Logic
Authors: Hammer Eric
Published: November 2020

The contributions of C.S. Peirce to the early history of prepositional and predicate logic are well known. Much less well known, however, is Peirce’s subsequent work (for more than ten years) on diagrammatic versions of prepositional and predicate logic. This work was considered by Peirce himself to be his most important contribution to logic. From his experience with chemistry and other parts of science, Peirce had become convinced that logic needed a more visually perspicuous notation, a notation that displayed the compound structure of propositions the way chemical diagrams displayed the compound structure of molecules. Peirce’s graphs for prepositional sentences are built up from sentence letters by the operations of enclosing a graph within a closed figure (interpreted as its negation) and juxtaposing two or more graphs on separate parts of the page (interpreted as their conjunction). For example, a graph like would be interpreted as “If A and B, then C” or “It is false that A and B and not-CV’ A graph such as would be read as “If A then B, but not C.” This chapter gives a modern analysis of Peirce’s diagrammatic version of the propositional calculus from the ground up. In particular, it is an investigation of just what is involved in formulating precisely the syntax, semantics, and proof theory of Peirce’s graphical approach to propositional logic. The project is interesting for several reasons. First, given Peirce’s importance in the history of .logic and his own opinion of the value of his work on graphs, it seems of historical interest to see to what his suggestions amounted. Second, Peirce’s work has gained a following in the computer science community, due especially to the work of Sowa [1984], whose system of conceptual graphs is modeled after Peirce’s work on diagrammatic approaches to prepositional and predicate logic. Third, in reconstructing Peirce’s graphical system we will confront a number of features characteristic of “visual” or “diagrammatic” inference, that is, inference that employs various forms of graphical representations in addition to, or in place of, sentences.
Synaptic Interactions in a Passive Dendritic Tree
Authors: Koch Christof
Published: November 2020

Nerve cells are the targets of many thousands of excitatory and inhibitory synapses. An extreme case are the Purkinje cells in the primate cerebellum, which receive between one and two hundred thousand synapses onto dendritic spines from an equal number of parallel fibers (Braitenberg and Atwood, 1958; Llinas and Walton, 1998). In fact, this structure has a crystalline-like quality to it, with each parallel fiber making exactly one synapse onto a spine of a Purkinje cell. For neocortical pyramidal cells, the total number of afferent synapses is about an order of magnitude lower (Larkman, 1991). These numbers need to be compared against the connectivity in the central processing unit (CPU) of modern computers, where the gate of a typical transistor usually receives input from one, two, or three other transistors or connects to one, two, or three other transistor gates. The large number of synapses converging onto a single cell provide the nervous system with a rich substratum for implementing a very large class of linear and nonlinear neuronal operations. As we discussed in the introductory chapter, it is only these latter ones, such as multiplication or a threshold operation, which are responsible for “computing” in the nontrivial sense of information processing. It therefore becomes crucial to study the nature of the interaction among two or more synaptic inputs located in the dendritic tree. Here, we restrict ourselves to passive dendritic trees, that is, to dendrites that do not contain voltage-dependent membrane conductances. While such an assumption seemed reasonable 20 or even 10 years ago, we now know that the dendritic trees of many, if not most, cells contain significant nonlinearities, including the ability to generate fast or slow all-or-none electrical events, so-called dendritic spikes. Indeed, truly passive dendrites may be the exception rather than the rule in the nervous In Sec. 1.5, we studied this interaction for the membrane patch model. With the addition of the dendritic tree, the nervous system has many more degrees of freedom to make use of, and the strength of the interaction depends on the relative spatial positioning, as we will see now. That this can be put to good use by the nervous system is shown by the following experimental observation and simple model.
Simplified Models of Individual Neurons
Authors: Koch Christof
Published: November 2020

In the previous thirteen chapters, we met and described, sometimes in excruciating detail, the constitutive elements making up the neuronal hardware: dendrites, synapses, voltagedependent conductances, axons, spines and calcium. We saw how, different from electronic circuits in which only very few levels of organization exist, the nervous systems has many tightly interlocking levels of organization that codepend on each other in crucial ways. It is now time to put some of these elements together into a functioning whole, a single nerve cell. With such a single nerve cell model in hand, we can ask functional questions, such as: at what time scale does it operate, what sort of operations can it carry out, and how good is it at encoding information. We begin this Herculean task by (1) completely neglecting the dendritic tree and (2) replacing the conductance-based description of the spiking process (e.g., the Hodgkin- Huxley equations) by one of two canonical descriptions. These two steps dramatically reduce the complexity of the problem of characterizing the electrical behavior of neurons. Instead of having to solve coupled, nonlinear partial differential equations, we are left with a single ordinary differential equation. Such simplifications allow us to formally treat networks of large numbers of interconnected neurons, as exemplified in the neural network literature, and to simulate their dynamics. Understanding any complex system always entails choosing a level of description that retains key properties of the system while removing those nonessential for the purpose at hand. The study of brains is no exception to this. Numerous simplified single-cell models have been proposed over the years, yet most of them can be reduced to just one of two forms. These can be distinguished by the form of their output: spike or pulse models generate discrete, all-or-none impulses.