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Showing papers by "University of Chicago published in 1988"


Journal ArticleDOI
TL;DR: In this article, the authors consider the prospects for constructing a neoclassical theory of growth and international trade that is consistent with some of the main features of economic development, and compare three models and compared to evidence.

16,965 citations


Journal ArticleDOI
TL;DR: This article investigated the relationship between management ownership and market valuation of the firm, as measured by Tobin's Q. In a 1980 cross-section of 371 Fortune 500 firms, they found evidence of a significant nonmonotonic relationship.

7,523 citations


Journal ArticleDOI
TL;DR: In this article, the power of dividend yields to forecast stock returns, measured by regression R2, increases with the return horizon, and the authors offer a two-part explanation: high autocorrelation causes the variance of expected returns to grow faster than the return-horizon.

3,811 citations


Journal ArticleDOI
TL;DR: In this article, residential segregation is viewed as a multidimensional phenomenon varying along five distinct axes of measurement: evenness exposure concentration centralization and clustering, and 20 indices of segregation are surveyed and related conceptually to 1 of the five dimensions.
Abstract: This paper conceives of residential segregation as a multidimensional phenomenon varying along 5 distinct axes of measurement: evenness exposure concentration centralization and clustering. 20 indices of segregation are surveyed and related conceptually to 1 of the 5 dimensions. Using data from a large set of US metropolitan areas the indices are intercorrelated and factor analyzed. Orthogonal and oblique rotations produce pattern matrices consistent with the postulated dimensional structure. Based on the factor analyses and other information 1 index was chosen to represent each of the 5 dimensions and these selections were confirmed with a principal components analysis. The paper recommends adopting these indices as standard indicators in future studies of segregation. (authors)

2,833 citations


Journal ArticleDOI
TL;DR: In this paper, a self-reported measure of pubertal status was used to assess the transition from childhood to adolescence in a longitudinal study of 335 young adolescent boys and girls.
Abstract: Puberty is a central process in the complex set of changes that constitutes the transition from childhood to adolescence. Research on the role of pubertal change in this transition has been impeded by the difficulty of assessing puberty in ways acceptable to young adolescents and others involved. Addressing this problem, this paper describes and presents norms for a selfreport measure of pubertal status. The measure was used twice annually over a period of three years in a longitudinal study of 335 young adolescent boys and girls. Data on a longitudinal subsample of 253 subjects are reported. The scale shows good reliability, as indicated by coefficient alpha. In addition, several sources of data suggest that these reports are valid. The availability of such a measure is important for studies, such as those based in schools, in which more direct measures of puberty may not be possible.

2,602 citations


Journal ArticleDOI
16 Sep 1988-Science
TL;DR: The practical need in biological conservation for understanding the interaction of demographic and genetic factors in extinction may provide a focus for fundamental advances at the interface of ecology and evolution.
Abstract: Predicting the extinction of single populations or species requires ecological and evolutionary information. Primary demographic factors affecting population dynamics include social structure, life history variation caused by environmental fluctuation, dispersal in spatially heterogeneous environments, and local extinction and colonization. In small populations, inbreeding can greatly reduce the average individual fitness, and loss of genetic variability from random genetic drift can diminish future adaptability to a changing environment. Theory and empirical examples suggest that demography is usually of more immediate importance than population genetics in determining the minimum viable sizes of wild populations. The practical need in biological conservation for understanding the interaction of demographic and genetic factors in extinction may provide a focus for fundamental advances at the interface of ecology and evolution.

2,282 citations


Journal ArticleDOI
TL;DR: On discute d'une technique alternative aux automates des gaz sur reseau pour etudier des proprietes hydrodynamiques, a savoir la modelisation d'un gaz reticulaire a l'aide d’une equation de Boltzman.
Abstract: We discuss an alternative technique to the lattice-gas automata for the study of hydrodynamic properties, namely, we propose to model the lattice gas with a Boltzmann equation. This approach completely eliminates the statistical noise that plagues the usual lattice-gas simulations and therefore permits simulations that demand much less computer time. It is estimated to be more efficient than the lattice-gas automata for intermediate to low Reynolds number $R\ensuremath{\lesssim}100$.

1,898 citations



Posted Content
TL;DR: In this article, the authors explore Rosenstein-Rodman's (1943) idea that simultaneous industrialization of many sectors of the economy can be profitable for all of them, even when no sector can break even industrializing alone.
Abstract: This paper explores Rosenstein-Rodman's (1943) idea that simultaneous industrialization of many sectors of the economy can be profitable for all of them, even when no sector can break even industrializing alone. We analyze this ides in the context of an imperfectly competitive economy with aggregate demand spillovers, and interpret the big push into industrialization as a move from a bad to a good equilibrium. We show that for two equilibria to exist, it must be the case that an industrializing firm raises the demand for products of other sectors through channels other than the contribution of its own profits to demand. For example, a firm paying high factory wages raises demand in other manufacturing sectors even if it loses money. In a similar vein, a firm investing today in order to produce at low cost tomorrow shifts income and hence demand for other goods into the future and so makes it more attractive for other firms also to invest today. Finally, an investing firm can benefit firms in other sectors if it uses a railroad or other shared infrastructure, and hence helps to defray the fixed cost of building the railroad. All these transmission mechanisms that help generate the big push seem to be of some relevance for less developed countries.

1,729 citations


Posted Content
TL;DR: This paper studied the joint processes of job mobility and wage growth among young men drawn from the Longitudinal Employee-Employer Data and concluded that the process of job changing for young workers, while apparently haphazard, is a critical component of workers' move toward the stable employment relations that characterize mature careers.
Abstract: We study the joint processes of job mobility and wage growth among young men drawn from the Longitudinal Employee-Employer Data. Following individuals at three month intervals from their entry into the labor market, we track career patterns of job changing and the evolution of wages for up to 15 years. Following an initial period of weak attachment to both the labor force and particular employers, careers tend to stabilize in the sense of strong labor force attachment and increasing durability of jobs. During the first 10 years in the labor market, a typical young worker will work for seven employers, which accounts for about two-thirds of the total number of jobs he will hold in his career. The evolution of wages plays a key role in this transition to stable employment: we estimate that wage gains at job changes account for at least a third of early-career wage growth, and that the wage is the key determinant of job changing decisions among young workers. We conclude that the process of job changing for young workers, while apparently haphazard, is a critical component of workers' move toward the stable employment relations that characterize mature careers.

1,450 citations


Journal ArticleDOI
TL;DR: Efforts at classifying multiple types of Ca 2+ channels according to differences in their gating, ionic conductance and pharmacology are summarized.

Journal ArticleDOI
08 Apr 1988-Cell
TL;DR: Sequence analysis of murine Egr-1 cDNA predicts a protein with three DNA binding zinc fingers, and results suggest that EGR1 may function as a transcriptional regulator in diverse biological processes.

Journal ArticleDOI
22 Apr 1988-Science
TL;DR: Theoretical predictions of an "inverted region," where increasing the driving force of the reaction will decrease its rate, have begun to be experimentally confirmed and a predicted nonlinear dependence of ET rates on the polarity of the solvent has also been confirmed.
Abstract: Intramolecular long-distance electron transfer (EI) has been actively studied in recent years in order to test existing theories in a quantitative way and to provide the necessary constants for predicting ET rates from simple structural parameters. Theoretical predictions of an "inverted region," where increasing the driving force of the reaction will decrease its rate, have begun to be experimentally confirmed. A predicted nonlinear dependence of ET rates on the polarity of the solvent has also been confirmed. This work has implications for the design of efficient photochemical charge-separation devices. Other studies have been directed toward determining the distance dependence of ET reactions. Model studies on different series of compounds give similar distance dependences. When different stereochemical structures are compared, it becomes apparent that geometrical factors must be taken into account. Finally, the mechanism of coupling between donor and acceptor in weakly interacting systems has become of major importance. The theoretical and experimental evidence favors a model in which coupling is provided by the interaction with the orbitals of the intervening molecular fragments, although more experimental evidence is needed.

Journal Article
TL;DR: Development of clinical techniques for relating hemodynamic and tensile properties to plaque location, stenosis, and composition should permit pathologists to provide new insights into the bases for the topographic and individual differences in plaque progression and outcome.
Abstract: Atherosclerosis affects the major elastic and muscular arteries, but some vessels are largely spared while others may be markedly diseased. The carotid bifurcation, the coronary arteries, the infrarenal abdominal aorta, and the vessels supplying the lower extremities are at highest risk. The propensity for plaque formation at bifurcations, branchings, and curvatures has led to conjectures that local mechanical factors such as wall shear stress and mural tensile stress potentiate atherogenesis. Recent studies of the human vessels at high risk, and of corresponding models, have provided quantitative evidence that plaques tend to occur where flow velocity and shear stress are reduced and flow departs from a laminar, unidirectional pattern. Such flow characteristics tend to increase the residence time of circulating particles in susceptible regions while particles are cleared rapidly from regions of relatively high wall shear stress and laminar unidirectional flow. The flow patterns associated with plaque localization are most prominent during systole. Long-term consequences are therefore likely to be greatly enhanced by elevated heart rate and may exert a selective effect on the coronary arteries. The point-by-point redistribution of wall tension at regions of geometric transition has not been quantitatively related to plaque localization. Enlargement of arteries as plaques increase in size and the associated modeling of plaque and wall configuration tend to preserve an adequate and regular lumen cross section. Hemodynamic forces appear to determine changes in vessel diameter so as to restore normal levels of wall shear stress, while wall thickness architecture, and composition are closely related to tensile stress. Hemodynamic forces may also be implicated in the symptom-producing destabilization of plaques, especially in relation to wall instabilities near stenoses. The relative roles of wall shear stress, tensile stress, and the metabolism of the artery wall in the progression and complication of atherosclerosis remain to be clarified. Development of clinical techniques for relating hemodynamic and tensile properties to plaque location, stenosis, and composition should permit pathologists to provide new insights into the bases for the topographic and individual differences in plaque progression and outcome.

Journal ArticleDOI
TL;DR: In this paper, an economic analysis of the linkages in fertility rates and capital accumulation across generations is developed considering the determination of fertility and capital consumption in each generation when wage rates and interest rates are parameters to each family and to open economies.
Abstract: An economic analysis of the linkages in fertility rates and capital accumulation across generations is developed considering the determination of fertility and capital accumulation in each generation when wage rates and interest rates are parameters to each family and to open economies. The model is based on the assumption that parents are altruistic toward their children. The utility of parents depends on their own consumption and on the utility of each child and the number of children. By relating the utility of children to their own consumption and to the utility of their children a dynastic utility function was obtained that depends on the consumption and number of descendants in all generations. The term "reformulation" was used because of the emphasis on dynastic utility model of altruism toward children and deriving the budget constraint and utility function of a dynastic family the model was applied to the Great Depression and World War II. The 1st-order conditions to maximize utility imply that fertility in any generation depends positively on the real interest rate and the degree of altruism and negatively on the rate of growth in per capita consumption from 1 generation to the next. Consumption of each descendant depends positively on the net cost of rearing a desdendant. Applying the model it is shown that the analysis is consistent with baby busts during the Depression and the war and with a baby boom after the war. The effects on fertility of child mortality subsidies to (or taxes on) children and social security and other transfer payments to adults were considered. The demand for surviving children rises during the transition to low child mortality but demand for survivors return to its prior level once mortality stabilizes at a low level. Fertility falls in response to declines in international real interest rates and increases in an economys rate of technological progress. Extending the analysis to include life-cycle variations in consumption earnings and utility fertility emerges as a function of expenditures on the subsistence and human capital of children but not of expenditures that simply raise the consumption of children. The path of aggregate consumption in demographic steady states does not depend on interest rates time preference or other determinants of life-cycle variations in consumption.

Posted Content
TL;DR: In this article, market liquidity is modeled as being determined by the demand and supply of immediacy and willingness to bear risk during the time period between the arrival of final buyers and sellers.
Abstract: Market liquidity is modeled as being determined by the demand and supply of immediacy. Exogenous liquidity events coupled with the risk of delayed trade create a demand for immediacy. Market makers supply immediacy by their continuous presence. and willingness to bear risk during the time period between the arrival of final buyers and sellers. In the long run the number of market makers adjusts to equate the supply and demand for immediacy. This determine the equilibrium level of liquidity in the market. The lower is the autocorrelation in rates of return, the higher is the equilibrium level of liquidity.

Journal ArticleDOI
TL;DR: In this article, the authors argue that an answer to an attitude question is the product of a four-stage process: first, respondents interpret the attitude question, determine what attitude the question is about, then they apply these beliefs and feelings in rendering the appropriate judgment, and finally they use this judgment to select a response.
Abstract: We begin this article with the assumption that attitudes are best understood as structures in longterm memory, and we look at the implications of this view for the response process in attitude surveys. More specifically, we assert that an answer to an attitude question is the product of a fourstage process. Respondents first interpret the attitude question, determining what attitude the question is about. They then retrieve relevant beliefs and feelings. Next, they apply these beliefs and feelings in rendering the appropriate judgment. Finally, they use this judgment to select a response. All four of the component processes can be affected by prior items. The prior items can provide a framework for interpreting later questions and can also make some responses appear to be redundant with earlier answers. The prior items can prime some beliefs, making them more accessible to the retrieval process. The prior items can suggest a norm or standard of comparison for making the judgment. Finally, the prior items can create consistency pressures or pressures to appear moderate. Because of the multiple processes involved, context effects are difficult to predict and sometimes difficult to replicate. We attempt to sort out when context is likely to affect later responses and include a list of the variables that affect the size and direction of the effects of context.

Journal ArticleDOI
14 Jul 1988-Nature
TL;DR: In this paper, the authors focus on recent ground-level observations from the Canadian baseline station at Alert (82.5° N, 62.3° W) and from aircraft that show that ozone destruction is occurring under the Arctic surface radiation inversion during March and April as the Sun rises.
Abstract: There is increasing evidence that at polar sunrise sunlight-induced changes in the composition of the lower Arctic atmosphere (0–2 km) are taking place that are important regarding the tropospheric cycles of ozone, bromine, sulphur oxides1, nitrogen oxides2 and possibly iodine3. Here we focus on recent ground-level observations from the Canadian baseline station at Alert (82.5° N, 62.3° W) and from aircraft that show that ozone destruction is occurring under the Arctic surface radiation inversion during March and April as the Sun rises. The destruction might be linked to catalytic reactions of BrOx radicals and the photochemistry of bromoform, which appears to have a biological origin in the Arctic Ocean. This may clarify previously unexplained regular springtime occurrences of ozone depletion at ground level in a 10-year data record at Barrow, Alaska4, as well as peaks in aerosol bromine observed throughout the Arctic in March and April3. Current information does not allow us to offer more than a speculative explanation for the chemical mechanisms leading to these phenomena.

Journal ArticleDOI
TL;DR: This work has considered four models in which the conformal invariance of electromagnetism is broken and the primeval magnetic fields which result can have astrophysically interesting strengths, but are very model-dependent.
Abstract: We study the production of large-scale (∼ Mpc) magnetic fields in inflationary Universe models. In the usual electromagnetic gauge theory, the photon field is conformally invariant and the magnetic fields that are produced during an inflationary epoch are uninterestingly small. We have considered four models in which the conformal invariance of electromagnetism is broken. The primeval magnetic fields which result can have astrophysically interesting strengths, but are very model-dependent.

Journal ArticleDOI
15 Apr 1988-Science
TL;DR: Complementary DNAs (cDNAs) encoding androgen receptors were obtained from human testis and rat ventral prostate cDNA libraries and indicated the presence of a cysteine-rich DNA-binding domain that is highly conserved in all steroid receptors.
Abstract: Complementary DNAs (cDNAs) encoding androgen receptors were obtained from human testis and rat ventral prostate cDNA libraries. The amino acid sequence deduced from the nucleotide sequences of the cDNAs indicated the presence of a cysteine-rich DNA-binding domain that is highly conserved in all steroid receptors. The human cDNA was transcribed and the RNA product was translated in cell-free systems to yield a 76-kilodalton protein. The protein was immunoprecipitable by human autoimmune antibodies to the androgen receptor. The protein bound androgens specifically and with high affinity.

Journal ArticleDOI
01 Jan 1988-Science
TL;DR: N-type calcium channels play a dominant role in the depolarization-evoked release of norepinephrine, and are involved in stimulus-secretion coupling.
Abstract: Multiple types of calcium channels have been found in neurons, but uncertainty remains about which ones are involved in stimulus-secretion coupling Two types of calcium channels in rat sympathetic neurons were described, and their relative importance in controlling norepinephrine release was analyzed N-type and L-type calcium channels differed in voltage dependence, unitary barium conductance, and pharmacology Nitrendipine inhibited activity of L-type channels but not N-type channels Potassium-evoked norepinephrine release was markedly reduced by cadmium and the conesnail peptide toxin omega-Conus geographus toxin VIA, agents that block both N- and L-type channels, but was little affected by nitrendipine at concentrations that strongly reduce calcium influx, as measured by fura-2 Thus N-type calcium channels play a dominant role in the depolarization-evoked release of norepinephrine

Book ChapterDOI
01 Aug 1988
TL;DR: In this paper, a more complete view of what human behavior and experience entail is provided, by observing what people do and what happens to them when they are not confined to the couch or the laboratory, but are involved in their normal lives in real ecological settings.
Abstract: In the ordinary course of events, psychologists observe human action either in clinical settings, where the “patient” is seeking therapeutic redress for some impairment, or in experimental settings, where the confines of the laboratory and the parameters of the experimental design allow only a tiny fraction of potential responses to be manifested. The theoretical models of human action that psychologists have constructed in the past half century reflect this poverty of observational data: They tend to be mechanistic, reductive, and biased in favor of pathology. To provide a more complete view of what human behavior and experience entail, it is necessary to begin observing what people do and what happens to them when they are not confined to the couch or the laboratory, but are involved in their normal lives in real ecological settings. In particular, it is important to observe them in those moments when their lives reach peaks of involvement that produce intense feelings of enjoyment and creativity. Without accounting for these aspects of experience, models of human behavior will remain one-sided and incomplete. The studies of the flow experience included in this volume attempt to provide evidence on which a more realistic model of human behavior can be built. The major psychological trends of this century – including drive theories, psychoanalysis, behaviorism, cognitive psychology, and the contemporary atheoretical neuropharmacological approaches – all share a common epistemology.

Journal Article
TL;DR: Data implicate IFN-gamma as a suppressive factor for the proliferation of the subset of HTL designated Th2, and suggest that the relative amounts of the various lymphokines present during an immune response may direct which T cell types increase in number.
Abstract: A biphasic dose-response curve was observed when the IL-1-dependent HTL clone D10 was exposed to IL-1 plus supernatants from some activated T cell clones but not others. The active component that inhibited proliferation at high concentrations of these supernatants appeared to be IFN-gamma based on the following findings: 1) the biphasic pattern of responsiveness correlated with the presence of IFN-gamma in the supernatants; 2) an anti-IFN-gamma mAb augmented the proliferation of D10 cells to these supernatants; 3) rIFN-gamma inhibited profoundly the response of D10 cells stimulated with rIL-1 plus supernatant from activated D10 cells or with rIL-1 plus rIL-4; 4) the response of D10 cells to rIL-1 plus rIL-2 also was inhibited by rIFN-gamma, although to a lesser extent. The proliferation of an additional Th2 clone stimulated with rIL-1 plus rIL-4 or rIL-2 also was inhibited by rIFN-gamma, implicating IFN-gamma as an inhibitory lymphokine for Th2 cells in general. rIFN-gamma did not affect the proliferation of two Th1 clones, nor did it affect the proliferation of an unconventional HTL clone which produces both IL-4 and IFN-gamma and proliferates in response to IL-2 or IL-4 in an IL-1-independent fashion. The proliferation of D10 cells stimulated by Ag or by immobilized anti-CD3 antibody also was blocked by rIFN-gamma, whereas IL-4 production in response to these stimuli was unaffected, indicating that proliferation and not general cell function was specifically inhibited. Collectively, these data implicate IFN-gamma as a suppressive factor for the proliferation of the subset of HTL designated Th2, and suggest that the relative amounts of the various lymphokines present during an immune response may direct which T cell types increase in number.

Journal ArticleDOI
01 Jul 1988-Science
TL;DR: Estradiol can act directly on osteoblasts by a receptor-mediated mechanism and thereby modulate the extracellular matrix and other proteins involved in the maintenance of skeletal mineralization and remodeling.
Abstract: High specific activity estradiol labeled with iodine-125 was used to detect approximately 200 saturable, high-affinity (dissociation constant approximately equal to 1.0 nM) nuclear binding sites in rat (ROS 17/2.8) and human (HOS TE85) clonal osteoblast-like osteosarcoma cells. Of the steroids tested, only testosterone exhibited significant cross-reactivity with estrogen binding. RNA blot analysis with a complementary DNA probe to the human estrogen receptor revealed putative receptor transcripts of 6 to 6.2 kilobases in both rat and human osteosarcoma cells. Type I procollagen and transforming growth factor-beta messenger RNA levels were enhanced in cultured human osteoblast-like cells treated with 1 nM estradiol. Thus, estrogen can act directly on osteoblasts by a receptor-mediated mechanism and thereby modulate the extracellular matrix and other proteins involved in the maintenance of skeletal mineralization and remodeling.

Journal ArticleDOI
22 Sep 1988-Nature
TL;DR: The crystal structure of the trp repressor/operator complex shows an extensive contact surface, including 24 direct and 6 solvent-mediated hydrogen bonds to the phosphate groups of the DNA as mentioned in this paper.
Abstract: The crystal structure of the trp repressor/operator complex shows an extensive contact surface, including 24 direct and 6 solvent-mediated hydrogen bonds to the phosphate groups of the DNA. There are no direct hydrogen bonds or non-polar contacts to the bases that can explain the repressor's specificity for the operator sequence. Rather, the sequence seems to be recognized indirectly through its effects on the geometry of the phosphate backbone, which in turn permits the formation of a stable interface. Water-mediated polar contacts to the bases also appear to contribute part of the specificity.

Book ChapterDOI
01 Jan 1988
TL;DR: In this article, a robust statistical procedure for estimating population parameters which are insensitive to the effect of outliers is proposed. But the robust procedure does not consider outliers, i.e., observations inconsistent with the assumed model of the random process generating the observations.
Abstract: One of the most vexing of problems in data analysis is the determination of whether or not to discard some observations because they are inconsistent with the rest of the observations and/or the probability distribution assumed to be the underlying distribution of the data. One direction of research activity related to this problem is that of the study of robust statistical procedures (cf. Huber [1981]), primarily procedures for estimating population parameters which are insensitive to the effect of “outliers”, i.e., observations inconsistent with the assumed model of the random process generating the observations. Typically, the robust procedure involves some “trimming” or down-weighting procedure, wherein some fraction of the extreme observations are automatically eliminated or given less weight to guard against the potential effect of outliers.

Journal ArticleDOI
TL;DR: In this article, the authors explore the determinants of corporate takeover methods and their outcomes and price effects and focus on the effect of leverage on the takeover method and outcome and obtain several other results on price effects.

Journal ArticleDOI
15 Apr 1988-Science
TL;DR: Results indicate that IL-1 may be an intrinsic neuromodulator in central nervous system pathways that mediate various metabolic functions of the acute phase reaction, including the body temperature changes that produce the febrile response.
Abstract: Interleukin-1 (IL-1) is a cytokine that mediates the acute phase reaction. Many of the actions of IL-1 involve direct effects on the central nervous system. However, IL-1 has not previously been identified as an intrinsic component within the brain, except in glial cells. An antiserum directed against human IL-1 beta was used to stain the human brain immunohistochemically for IL-1 beta-like immunoreactive neural elements. IL-1 beta-immunoreactive fibers were found innervating the key endocrine and autonomic cell groups that control the central components of the acute phase reaction. These results indicate that IL-1 may be an intrinsic neuromodulator in central nervous system pathways that mediate various metabolic functions of the acute phase reaction, including the body temperature changes that produce the febrile response.

Journal ArticleDOI
TL;DR: In obesity, although hypersecretion of insulin can be documented, the temporal pattern of secretion is largely unaltered, which suggests that the functioning beta cell mass is enhance, but normal regulatory mechanisms influencing secretion are still operative.
Abstract: The pattern of endogenous insulin secretion over a 24-h period, which included three mixed meals, was evaluated in 14 normal volunteers and 15 obese subjects. Insulin secretory rates were calculated from plasma C-peptide levels using individually derived C-peptide kinetic parameters and a validated open two-compartment model of peripheral C-peptide kinetics. Insulin secretion rates were consistently elevated in the obese subjects under basal conditions (11.6 +/- 1.2 vs. 5.4 +/- 0.5 nmol/h) and in the 4 h after breakfast (139 +/- 15 vs. 63 +/- 5 nmol/4 h, P less than 0.001), lunch (152 +/- 16 vs. 67 +/- 5 nmol/4 h, P less than 0.001), and dinner (145 +/- 18 vs. 65 +/- 6 nmol/4 h, P less than 0.001). In the normal subjects, basal insulin secretion represented 50 +/- 2.1% of total 24-h insulin production, insulin secretion returned to baseline between meals, and equal quantities of insulin were secreted in the 4 h after breakfast, lunch, and dinner, despite the fact that subjects consumed half the number of calories at breakfast compared to lunch and dinner. Overall glucose responses were also similar after the three meals. In contrast, the pattern of insulin secretion in obese subjects was largely normal, albeit set at a higher level. However, the insulin secretion rate after meals did not return to baseline, and the secretion rate immediately before lunch (350.5 +/- 81.9 pmol/min) and dinner (373.6 +/- 64.8 pmol/min) was considerably higher than the secretion rate immediately before breakfast (175.5 +/- 18.5 pmol/min). In these overweight subjects, the glucose response after lunch was lower than after dinner. Analysis of individual 24-h insulin secretory profiles in the normal subjects revealed that insulin secretion was pulsatile. On average 11.1 +/- 0.5 pulses were produced in each 24-h period. The most prevalent temporal distribution of postmeal secretory pulses was two pulses after breakfast and three pulses after both lunch and dinner. Insulin secretion was also pulsatile during the period without meal stimuli: 3.9 +/- 0.3 pulses occurred during the period of overnight sampling and in the 3-h period before ingestion of the breakfast meal. In the obese subjects, the number and timing of secretory pulses was similar to those of normal volunteers, although the amplitude of the pulses was significantly greater. In both groups of subjects, greater than 80% of insulin pulses were concomitant with a pulse in glucose concentration in the postmeal period. The concomitancy rate was significantly lower in the interval without the meal stimuli, averaging 47% in both groups. Thus in obesity, although hypersecretion of insulin can be documented, the temporal pattern of secretion i s largely unaltered, which suggests that the functioning beta cell mass is enhance, but normal regulatory mechanisms influencing secretion are still operative.

Journal ArticleDOI
TL;DR: In this article, the authors derive conditions under which the simple majority voting rule for electing controlling management and one share-one vote constitute a socially optimal corporate governance rule and show that other majority rules and/or multiple classes of shares are not socially optimal.