Showing papers by "University of Chicago published in 1980"

Regression Models for Ordinal Data

Abstract: SUMMARY A general class of regression models for ordinal data is developed and discussed. These models utilize the ordinal nature of the data by describing various modes of stochastic ordering and this eliminates the need for assigning scores or otherwise assuming cardinality instead of ordinality. Two models in particular, the proportional odds and the proportional hazards models are likely to be most useful in practice because of the simplicity of their interpretation. These linear models are shown to be multivariate extensions of generalized linear models. Extensions to non-linear models are discussed and it is shown that even here the method of iteratively reweighted least squares converges to the maximum likelihood estimate, a property which greatly simplifies the necessary computation. Applications are discussed with the aid of examples.

Evolution in age-structured populations

Abstract: The populations of many species of animals and plants are age-structured, i.e. the individuals present at any one time were born over a range of different times, and their fertility and survival depend on age. The properties of such populations are important for interpreting experiments and observations on the genetics of populations for animal and plant breeding, and for understanding the evolution of features of life-histories such as senescence and time of reproduction. In this new edition Brian Charlesworth provides a comprehensive review of the basic mathematical theory of the demography and genetics of age-structured populations. The mathematical level of the book is such that it will be accessible to anyone with a knowledge of basic calculus and linear algebra.

Sexual dimorphism, sexual selection, and adaptation in polygenic characters.

Abstract: Conspicuous sexual dimorphism is a feature of many species of higher animals. The genetic basis of variation in metrical characters, including that in sexual dimorphism between families or lines, is usually polygenic (Falconer, 1960; Frankham, 1968b; Wright, 1968, 1977; Bird and Schaffer, 1972; Ehrman and Parsons, 1976). Genetic experiments on mice, birds and Drosophila flies indicate that artificial selection practiced on a character of one sex causes not only a direct response of the character in the selected sex, but also a correlated response of the homologous character, if any, in the opposite sex (Shaklee et al., 1952; Harrison, 1953; Korkman, 1957; Becker et al., 1964; Eisen and Legates, 1966; Frankham, 1968a, 1968b; Eisen and Hanrahan, 1972). Such correlated selective responses are attributable to pleiotropy (and linkage) of genes affecting the characters of both sexes, that is, correlations between the additive effects of genes as expressed in males and females. The genetic correlation between homologous characters of the sexes is often quite high (op. cit.). As will be shown, this greatly restricts the rate of evolution of sexual dimorphism relative to that for the average phenotype of the two sexes. Sexual dimorphism may result from natural and/or sexual selection. Darwin (1874, Part 2) elucidated how natural selection operating differently on males and females arises from their distinctive roles in reproduction, or from competition between the sexes for resources such as food, leading to adaptive sexual dimorphism. He also reasoned that intrasexual contests for mates and intersexual mating preferences exert sexual selection, usually on the males, producing sexual dimorphism which is maladaptive with respect to natural selection. Comparisons within and between closely related species led Darwin to conclude that adult males typically are more modified than adult females or juveniles of either sex, but that females have often acquired male characters by "transference." It was difficult for Darwin to believe that sex-limitation of characters could evolve by selection, but Fisher (1958, Ch. 6) outlined how divergent selection on the two sexes could accumulate genes with different effects in males and females, causing a character at first expressed equally in both sexes to become sexually dimorphic and finally sex-limited. The strength of sexual selection is enhanced by a polygamous mating system, but the possibility of sexual selection in monogamous systems of mating exists due to male competition for early-breeding females, and mate choice exercised by these females (Darwin, 1874; Fisher, 1958; O'Donald, 1977). Systems of mating are often thought to evolve in response to ecological pressures (reviewed by Selander, 1972; Brown, 1975; Emlen and Oring, 1977), although mating preferences may be self-reinforcing (Fisher, 1958; O'Donald, 1967, 1977; Lande, unpubl.). Darwin and Fisher described qualitative methods by which an observed sexual dimorphism could be attributed mainly to either natural or sexual selection. To assign natural selection as the primary cause requires ecological observations that males and females follow different ways of life and employ the dimorphic character(s) adaptively in their distinct modes of survival or reproduction. Darwin presented several such examples, mostly among the lower classes of animals. Selander (1972) 292

The Cost Of Thinking

Abstract: A theory and methodology are developed for explicitly considering the cost of comparing diverse choice alternatives. The theory allows (1) explicit analytical measures of the cost of using various simplified decision strategies, and (2) predictions regarding the distribution of mistakes a consumer is likely to make when reducing decision-making effort.

Negara: The Theatre State in Nineteenth-Century Bali

Abstract: Combining great learning, interpretative originality, analytical sensitivity, and a charismatic prose style, Clifford Geertz has produced a lasting body of work with influence throughout the humanities and social sciences, and remains the foremost anthropologist in America. His 1980 book Negara analyzed the social organization of Bali before it was colonized by the Dutch in 1906. Here Geertz applied his widely influential method of cultural interpretation to the myths, ceremonies, rituals, and symbols of a precolonial state. He found that the nineteenth-century Balinese state defied easy conceptualization by the familiar models of political theory and the standard Western approaches to understanding politics. Negara means 'country' or 'seat of political authority' in Indonesian. In Bali Geertz found negara to be a 'theatre state,' governed by rituals and symbols rather than by force. The Balinese state did not specialize in tyranny, conquest, or effective administration. Instead, it emphasized spectacle. The elaborate ceremonies and productions the state created were 'not means to political ends: they were the ends themselves, they were what the state was for.... Power served pomp, not pomp power.' Geertz argued more forcefully in Negara than in any of his other books for the fundamental importance of the culture of politics to a society. Much of Geertz's previous work--including his world-famous essay on the Balinese cockfight--can be seen as leading up to the full portrait of the 'poetics of power' that Negara so vividly depicts. Review: 'The main purpose of Geertz's study is to delineate the general structure of the Negara by focusing on one particularly well-documented case, that of Bali in the era preceding the Dutch invasion of 1906. The outcome is a fascinating and remarkable book.'--The New York Review of Books

DNA gyrase and the supercoiling of DNA

Abstract: Negative supercoiling of bacterial DNA by DNA gyrase influences all metabolic processes involving DNA and is essential for replication. Gyrase supercoils DNA by a mechanism called sign inversion, whereby a positive supercoil is directly inverted to a negative one by passing a DNA segment through a transient double-strand break. Reversal of this scheme relaxes DNA, and this mechanism also accounts for the ability of gyrase to catenate and uncatenate DNA rings. Each round of supercoiling is driven by a conformational change induced by adenosine triphosphate (ATP) binding: ATP hydrolysis permits fresh cycles. The inhibition of gyrase by two classes of antimicrobials reflects its composition from two reversibly associated subunits. The A subunit is particularly associated with the concerted breakage-and-rejoining of DNA and the B subunit mediates energy transduction. Gyrase is a prototype for a growing class of prokaryotic and eukaryotic topoisomerases that interconvert complex forms by way of transient double-strand breaks.

A rapid method for the regional dissection of the rat brain

Abstract: A method is described for the rapid dissection of seventeen areas of the rat brain. Regions from fresh unfrozen brain tissue are dissected from coronal brain slices obtained with use of a cutting block. This method is applicable to pharmacological and behavioral studies which require the dissection of numerous brains during short time intervals.

Carbonic metamorphism, granulites and crustal growth

Abstract: Stabilization of early crust against melting by high radioactivity and against resorption into the mantle by fast convective overturn requires that water and heat producers were flushed upwards within 50 Myr of accretion. Creation of a refractory base of granulite by metamorphism associated with CO2 vapour explains CO2-rich fluid inclusions in ancient high-grade rocks, minor-element depletions and local phenomena of arrested development of charnockite in Precambrian terrains. The hot-spot and plate-tectonic models of Precambrian crustal evolution lead to different schemes for CO2 delivery to continental roots. New tectonic concepts may be needed to explain carbonic metamorphism and other features of early crustal evolution.

Posterior odds ratios for selected regression hypotheses

Abstract: Bayesian posterior odds ratios for frequently encountered hypotheses about parameters of the normal linear multiple regression model are derived and discussed. For the particular prior distributions utilized, it is found that the posterior odds ratios can be well approximated by functions that are monotonic in usual sampling theoryF statistics. Some implications of this finding and the relation of our work to the pioneering work of Jeffreys and others are considered. Tabulations of odds ratios are provided and discussed.

Arterial foam cells with distinctive immunomorphologic and histochemical features of macrophages.

Abstract: A variable population of fat-filled "foam" cells in diet-induced experimental arterial intimal plaques of rabbits and monkeys were analyzed for several features characteristic of macrophages. These included: 1) surface binding and phagocytosis of antibody-coated or complement-coated erythrocytes to detect specific surface receptors; 2) cytochemical tests and ultrastructural features to evaluate cell function and structure; and 3) rapid adherence to glass, a feature of macrophage activity, to isolate and identify a homogeneous population of fat-filled foam cells from excised and disrupted arterial lesions. Mixed populations of cells grown in culture from explants of lesions were also analyzed and lipid-filled cells were studied in histologic sections of adjacent lesions. Eighty to ninety percent of the easily dislodged glass-adherent cells from lesions had surface receptors for the Fc portion of immunoglobulin G and for the third component of complement. Coated red blood cells were readily phagocytized, but noncoated cells were not. Acid lipase activity was demonstrated in the Fc-receptor-positive cells. These cells were also devoid of ultrastructural features of smooth muscle. Among the cells growing or migrating out of explants, a population of large round foam cells possessed all of the macrophage features found in the glass-adherent cells from lesions and lacked ultrastructural characteristics of smooth muscle. Fusiform lipid vacuolated cells also grew out of the explants but did not exhibit surface receptors, failed to phagocytize coated or noncoated erythrocytes and did not stain for acid lipase activity; these cells showed distinctive morphologic features of smooth muscle. In histologic sections of nearby lesions foam cells that showed macrophage characteristics, ie, acid lipase activity and the presence of lysozymelike antigen, lacked ultrastructural smooth muscle features. Smooth muscle cells in lesion sections often contained lipid but demonstrated no lysozyme or acid lipase activity. The occurrence of a population of cells with several functional and structural features of macrophages among the lipid-laden cells of experimental diet-induced arterial lesions suggests that some foam cells may be derived from monocytes. An alternative explanation, that metabolically altered autochthonous arterial wall cells assume one or more characteristics of mononuclear phagocytes is less likely, since some of the markers used in these experiments are unrelated. Both explanations deserve further careful study.

Bulimia. Its incidence and clinical importance in patients with anorexia nervosa.

Abstract: • Among the various eating patterns encountered in anorexia nervosa, the occurrence of bulimia (rapid consumption of large amounts of food in a short period of time) is a perplexing phenomenon, because its presence contradicts the common belief that patients with anorexia nervosa are always firm in their abstinence from food. We studied the eating habits of 105 hospitalized female patients within the context of a prospective treatment study on anorexia nervosa: 53% had achieved weight loss by consistently fasting, whereas 47% periodically resorted to bulimia. The two groups were contrasted with regard to their developmental and psychosocial history, clinical characteristics, and psychiatric symptomatology. Fasting patients were more introverted, more often denied hunger, and displayed little overt psychic distress. In contrast, bulimic patients were more extroverted, admitted more frequently to a strong appetite and tended to be older. Vomiting was frequent, and kleptomania almost exclusively present in bulimic patients, who manifested greater anxiety, depression, guilt, interpersonal sensitivity, and had more somatic complaints. This association of bulimia with certain personality features and a distinct psychiatric symptomatology suggests that patients with bulimia form a subgroup among patients with anorexia nervosa.

Polynomial approximation of functions in Sobolev spaces

Abstract: Constructive proofs and several generalizations of approximation results of J. H. Bramble and S. R. Hilbert are presented. Using an averaged Taylor series, we represent a function as a polynomial plus a remainder. The remainder can be manipulated in many ways to give different types of bounds. Approximation of functions in fractional order Sobolev spaces is treated as well as the usual integer order spaces and several nonstandard Sobolev-like spaces.

Processing mechanisms in the biosynthesis of proteins.

Abstract: Limited proteolysis is a widely occurring mechanism in protein biosynthesis. Protein precursors can be classified according to their functions, localization within cell compartments, and enzymic cleavage mechanisms. The presecretory proteins represent an important class of very rapidly turning over precursors which play an early role in the sequestration of secretory products and whose cleavage appears to be intimately associated with structures formed at the ribosome-membrane junction during protein synthesis. A model is proposed which predicts that the prepeptide forms a beta-pleated sheet structure with other components of the membrane which results in the transfer of a loop of peptide across the microsomal membrane. Proinsulin is representative of the general class of proproteins that are processed post-translationally within their secretory cells either during the formation and maturation of secretory granules (peptides hormones and neurotransmitters, serum albumins) or during the assembly of macromolecular structures (virus capsules, membrane-associated enzyme complexes). The former group are cleaved by Golgi-associated proteases having tryptic and carboxypeptidase B-like specificity. Some precursors are secreted as such and processed extracellularly either in the circulation or at special sites (procollagens, zymogens, provenoms, vitellogenins).

Chemical Composition of Earth, Venus, and Mercury

Abstract: Model compositions of Earth, Venus, and Mercury are calculated from the premise that planets and chondrites underwent four identical fractionation processes in the solar nebula. Because elements of similar properties stay together in these processes, five constraints suffice to define the composition of a planet: mass of the core, abundance of U, and the ratios K/U, Tl/U, and FeO/(FeO + MgO). Complete abundance tables, and normative mineralogies, are given for all three planets. Review of available data shows only a few gross trends for the inner planets: FeO decreases with heliocentric distance, whereas volatiles are depleted and refractories are enriched in the smaller planets.

“Diamond-like” 3-fold coordinated amorphous carbon

Abstract: Evaporated and sputtered a-C films deposited at L.N. temperature were prepared and studied as a function of annealing using Raman, electron energy loss, and ESR techniques. The reduced Raman spectra of virgin films reflect the one phonon density of states of graphite. Moreover, no evidence for diamond bonding is found from the electron energy loss experiment. Upon annealing, graphitic structural correlations develop within bounded islands of carbon atoms. This picture is consistent with ESR measurements which yield 3 × 1019 spins/cm3 independent of annealing but a resonnance line (g = 2.002 ± .0005) that narrows with annealing. A model based solely on a three-fold coordinated random network structure will be presented to explain the “diamond-like” physical properties of a-C films and their changes with annealing.