Showing papers on "Population published in 1983"
TL;DR: Measures of directional and stabilizing selection on each of a set of phenotypically correlated characters are derived, retrospective, based on observed changes in the multivariate distribution of characters within a generation, not on the evolutionary response to selection.
Abstract: Natural selection acts on phenotypes, regardless of their genetic basis, and produces immediate phenotypic effects within a generation that can be measured without recourse to principles of heredity or evolution. In contrast, evolutionary response to selection, the genetic change that occurs from one generation to the next, does depend on genetic variation. Animal and plant breeders routinely distinguish phenotypic selection from evolutionary response to selection (Mayo, 1980; Falconer, 1981). Upon making this critical distinction, emphasized by Haldane (1954), precise methods can be formulated for the measurement of phenotypic natural selection. Correlations between characters seriously complicate the measurement of phenotypic selection, because selection on a particular trait produces not only a direct effect on the distribution of that trait in a population, but also produces indirect effects on the distribution of correlated characters. The problem of character correlations has been largely ignored in current methods for measuring natural selection on quantitative traits. Selection has usually been treated as if it acted only on single characters (e.g., Haldane, 1954; Van Valen, 1965a; O'Donald, 1968, 1970; reviewed by Johnson, 1976 Ch. 7). This is obviously a tremendous oversimplification, since natural selection acts on many characters simultaneously and phenotypic correlations between traits are ubiquitous. In an important but neglected paper, Pearson (1903) showed that multivariate statistics could be used to disentangle the direct and indirect effects of selection to determine which traits in a correlated ensemble are the focus of direct selection. Here we extend and generalize Pearson's major results. The purpose of this paper is to derive measures of directional and stabilizing (or disruptive) selection on each of a set of phenotypically correlated characters. The analysis is retrospective, based on observed changes in the multivariate distribution of characters within a generation, not on the evolutionary response to selection. Nevertheless, the measures we propose have a close connection with equations for evolutionary change. Many other commonly used measures of the intensity of selection (such as selective mortality, change in mean fitness, variance in fitness, or estimates of particular forms of fitness functions) have little predictive value in relation to evolutionary change in quantitative traits. To demonstrate the utility of our approach, we analyze selection on four morphological characters in a population of pentatomid bugs during a brief period of high mortality. We also summarize a multivariate selection analysis on nine morphological characters of house sparrows caught in a severe winter storm, using the classic data of Bumpus (1899). Direct observations and measurements of natural selection serve to clarify one of the major factors of evolution. Critiques of the "adaptationist program" (Lewontin, 1978; Gould and Lewontin, 1979) stress that adaptation and selection are often invoked without strong supporting evidence. We suggest quantitative measurements of selection as the best alternative to the fabrication of adaptive scenarios. Our optimism that measurement can replace rhetorical claims for adaptation and selection is founded in the growing success of field workers in their efforts to measure major components of fitness in natural populations (e.g., Thornhill, 1976; Howard, 1979; Downhower and Brown, 1980; Boag and Grant, 1981; Clutton-Brock et
4,990 citations
TL;DR: These studies indicate that the estimates of the average number of nucleotide differences and nucleon diversity have a large variance, and a large part of this variance is due to stochastic factors.
Abstract: With the aim of analyzing and interpreting data on DNA polymorphism obtained by DNA sequencing or restriction enzyme technique, a mathematical theory on the expected evolutionary relationship among DNA sequences (nucleons) sampled is developed under the assumption that the evolutionary change of nucleons is determined solely by mutation and random genetic drift. The statistical property of the number of nucleotide differences between randomly chosen nucleons and that of heterozygosity or nucleon diversity is investigated using this theory. These studies indicate that the estimates of the average number of nucleotide differences and nucleon diversity have a large variance, and a large part of this variance is due to stochastic factors. Therefore, increasing sample size does not help reduce the variance significantly The distribution of sample allele (nucleomorph) frequencies is also studied, and it is shown that a small number of samples are sufficient in order to know the distribution pattern.
3,038 citations
Book•
01 Jan 1983
TL;DR: This book provides an introduction to statistical methods for analysing data in the form of spatial point distributions, described in intuitive terms and illustrated by many applications to real data drawn from the biological and biomedical sciences.
Abstract: A spatial point pattern is a set of data consisting of a map of points These points might represent, for example, cases of a disease in a human or animal population, or trees in a forest, or cells in a microscopic tissue section This book provides an introduction to statistical methods for analysing data in the form of spatial point distributions Theoretical results are described in intuitive terms and statistical methods are illustrated by many applications to real data drawn from the biological and biomedical sciences
2,911 citations
Posted Content•
TL;DR: In this article, the authors explore why organizations tend to be increasingly and inevitably homogeneous in their forms and practices, and suggest that organizational fields are structured into an organizational field by powerful forces that lead them to become similar.
Abstract: Instead of examining why organizations are dissimilar, this study explores why organizations tend to be increasingly and inevitably homogenous in their forms and practices. Organizations in a similar line of work are structured into an organizational field by powerful forces that lead them to become similar. Rather than the causes of rationalization and bureaucratization suggested by Max Weber, including competition and the need for efficiency, institutional similarity is due to the structuration of organizational fields, a process caused largely by the state and the professions, which are the great rationalizers of the late 20th century. In highly structured organizational fields, rational efforts of individuals aggregately lead to structural, cultural, and output homogeneity. Homogenization is best captured by the concept of isomorphism, the process whereby one element in a population resembles others that confront the same environmental conditions. The two types of isomorphism are competitive and institutional. Three processes lead to organizational similarity: (1) coercive isomorphism stemming from political influence and the problem of legitimacy; (2) mimetic isomorphism resulting from uniform responses to uncertainty; and (3) normative isomorphism associated with professionalism. While these isomorphic processes improve organizational transactions, they do not necessarily increase internal efficiency. Twelve hypotheses are offered for further research about which organizational fields will be most homogenous. These hypotheses relate the impact of resource centralization and dependency, goal ambiguity and technical uncertainty, and professionalism and structuration on isomorphic change. Finally, useful implications of the study for theories of organizations and social change are offered. (TNM)
2,879 citations
TL;DR: Fundamental differences between the response of woody plants and graminoids to vertebrate herbivory suggest that the dynamics of browsing systems and grazing systems are qualitatively different.
Abstract: The evolutionary response of plants to herbivory is constrained by the availability of resources in the environment. Woody plants adapted to low-resource environments have intrinsically slow growth rates that limit their capacity to grow rapidly beyond the reach of most browsing mammals. Their low capacity to acquire resources limits their potential for compensatory growth which would otherwise enable them to replace tissue destroyed by browsing. Plants adapted to low-resource environments have responded to browsing by evolving strong constitutive defenses with relatively low ontogenetic plasticity. Because nutrients are often more limiting than light in boreal forests, slowly growing boreal forest trees utilize carbon-based rather than nitrogen-based defenses. More rapidly growing shade-intolerant trees that are adapted to growth in high-resource environments are selected for competitive ability and can grow rapidly beyond the range of most browsing mammals. Moreover, these plants have the carbon and nutrient reserves necessary to replace tissue lost to browsing through compensatory growth. However, because browsing of juvenile plants reduces vertical growth and thus competitive ability, these plants are selected for resistance to browsing during the juvenile growth phase. Consequently, early successional boreal forest trees have responded to browsing by evolving strong defenses during juvenility only. Because severe pruning causes woody plants to revert to a juvenile form, resistance of woody plants to hares increases after severe hare browsing as occurs during hare population outbreaks. This increase in browsing resistance may play a significant role in boreal forest plant-hare interactions. Unlike woody plants, graminoids retain large reserves of carbon and nutrients below ground in both low-resource and high-resource environments and can respond to severe grazing through compensatory growth. These fundamental differences between the response of woody plants and graminoids to vertebrate herbivory suggest that the dynamics of browsing systems and grazing systems are qualitatively different.
2,439 citations
TL;DR: Application of practical diagnostic criteria for standard clinical use should assist in clinical management of nonspecific vaginitis and in further study of the microbiologic and biochemical correlates and the pathogenesis of this mild but quite prevalent disease.
2,273 citations
TL;DR: There is documented evidence that measures of self-maintaining function can be reliably used in clinical evaluations as well as in program evaluations and in planning and that evaluation by these measures helps to identify problems that require treatment or care.
Abstract: The aging of the population of the United States and a concern for the well-being of older people have hastened the emergence of measures of functional health. Among these, measures of basic activities of daily living, mobility, and instrumental activities of daily living have been particularly useful and are now widely available. Many are defined in similar terms and are built into available comprehensive instruments. Although studies of reliability and validity continue to be needed, especially of predictive validity, there is documented evidence that these measures of self-maintaining function can be reliably used in clinical evaluations as well as in program evaluations and in planning. Current scientific evidence indicates that evaluation by these measures helps to identify problems that require treatment or care. Such evaluation also produces useful information about prognosis and is important in monitoring the health and illness of elderly people.
2,083 citations
TL;DR: Improved prediction equations for each sex by age group for 5 spirometric and flow-volume variables are derived and "Normal" limits are proposed that take into consideration the between-subject variability and non-Gaussian distribution of the various measurements.
Abstract: On the basis of their answers to a self-administered questionnaire, 697 nonsmoking healthy subjects were chosen from a randomly selected sample representative of the white non-Mexican-American population of Tucson, Arizona, enrolled in a longitudinal study of respiratory health. For each subject, the first satisfactory set of flow-volume data obtained during the first 3 consecutive surveys was selected for analysis. For forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), the single best value for each subject was selected. Other flow-volume measurements were derived from the single test with the best sum FEV, plus FVC. These data were used to derive improved prediction equations for each sex by age group for 5 spirometric and flow-volume variables. The resulting predicted values demonstrate the effects of development, maturation, and senescence on ventilatory function. "Normal" limits are proposed that take into consideration the between-subject variability and non-Gaussian distribution of the various measurements.
1,911 citations
Journal Article•
TL;DR: The data indicate that the DCFH oxidation assay is quantitatively related to the oxidative metabolic burst of PMNL, and they strongly suggest that the reaction is mediated by H2O2 generated by the PMNL.
Abstract: We have developed a quantitative assay to monitor the oxidative burst (H2O2 production) of polymorphonuclear leukocytes (PMNL) using single cell analysis by flow cytometry, and have examined whether PMNL respond to membrane stimulation with an all-or-none oxidative burst. During incubation with normal neutrophils, dichlorofluorescin diacetate diffused into the cells, was hydrolyzed to 2',7'-dichlorofluorescin (DCFH) and was thereby trapped within the cells. The intracellular DCFH, a nonfluorescent fluorescein analogue, was oxidized to highly fluorescent 2',7'-dichlorofluorescein (DCF) by PMNL stimulated by phorbol myristate acetate (PMA). That the oxidative product was DCF was shown by excitation/emission spectra and by mass spectrometry of the product from PMA-stimulated PMNL. Normal resting and PMA-stimulated PMNL oxidized 6.9 +/- 0.7 and 160 +/- 13 attomoles DCF per cell, respectively, in 15 min. Absence of calcium and magnesium ions and/or addition of 2 mM EDTA did not inhibit DCF formation by PMNL stimulated by 100 ng/ml PMA. Since EDTA prevented aggregation of PMNL (even when stimulated by 100 ng/ml PMA), which would prevent accurate flow cytometric analysis, further experiments were performed with EDTA in the medium. A close correlation between average DCFH oxidation and hexose monophosphate shunt stimulation was demonstrated using cells from patients whose PMNL had oxidative metabolic defects of varying severity. Intracellular DCFH was also oxidized by reagent H2O2 or oxygen derivatives generated by glucose oxidase + glucose or by xanthine oxidase + acetaldehyde; DCFH oxidation by these systems was inhibited by catalase but unchanged by superoxide dismutase. The data indicate that the DCFH oxidation assay is quantitatively related to the oxidative metabolic burst of PMNL, and they strongly suggest that the reaction is mediated by H2O2 generated by the PMNL. Incubation of PMNL with varying concentrations of PMA caused graded responses by all PMNL present; i.e., 1 ng/ml PMA caused a mean response of 34% maximal with a single population of responding PMNL (rather than 66% resting and 34% fully stimulated as predicted by the all-or-none hypothesis). Thus, with these assay conditions, oxidative product formation by PMNL occurs as a graded response to membrane stimulation by PMA.
1,790 citations
TL;DR: Simulations of a monoecious population mating at random showed that a weighted ratio of single-locus estimators performed better than an unweighted average or a least squares estimator in the drift situation.
Abstract: A distance measure for populations diverging by drift only is based on the coancestry coefficient θ, and three estimators of the distance D = - ln (1 - θ) are constructed for multiallelic, multilocus data. Simulations of a monoecious population mating at random showed that a weighted ratio of single-locus estimators performed better than an unweighted average or a least squares estimator. Jackknifing over loci provided satisfactory variance estimates of distance values. In the drift situation, in which mutation is excluded, the weighted estimator of D appears to be a better measure of distance than others that have appeared in the literature.
1,776 citations
TL;DR: In this paper, the main states of India are broadly grouped into two demographic regimes, i.e., northern kinship/low female autonomy and southern kinship /high female autonomy, and the analysis suggests that family social status is probably the most important element in comprehending Indias demographic situation.
Abstract: The main states of India are broadly grouped into 2 demographic regimes. In contrast to states in the north southern states are characterized by lower marital fertility later age at marriage lower infant and child mortality and comparatively low ratios of female to male infant and child mortality. The division between the 2 regimes broadly coincides with the division areas of northern kinship/low female autonomy and southern kinship/high female autonomy. The analysis suggests that family social status is probably the most important element in comprehending Indias demographic situation. Women in the south tend to be more active in the labor force are more likely to take innovative action in adopting fertility control and are more apt to utilize health services for themselves and their children. Changes in India are also compared to those other South Asian countries. (authors modified) (summaries in ENG FRE SPA)
TL;DR: A permanent human cell line, EA .
Abstract: A permanent human cell line, EA . hy 926, has been established that expresses at least one highly differentiated function of vascular endothelium, factor VIII-related antigen. This line was derived by fusing human umbilical vein endothelial cells with the permanent human cell line A549. Hybrid cells that survived in selective medium had more chromosomes than either progenitor cell type and included a marker chromosome from the A549 line. Factor VIII-related antigen can be identified intracellularly in the hybrids by immunofluorescence and accumulates in the culture fluid. Expression of factor VIII-related antigen by these hybrid cells has been maintained for more than 100 cumulative population doublings, including more than 50 passages and three cloning steps. This is evidence that EA . hy 926 represents a permanent line.
TL;DR: Though the structures presented in crystallographic models of macromolecules appear to possess rock-like solidity, real proteins and nucleic acids are not particularly rigid.
Abstract: Though the structures presented in crystallographic models of macromolecules appear to possess rock-like solidity, real proteins and nucleic acids are not particularly rigid. Most structural work to date has centred upon the native state of macromolecules, the most probable macromolecular form. But the native state of a molecule is merely its most abundant form, certainly not its only form. Thermodynamics requires that all other possible structural forms, however improbable, must also exist, albeit with representation corresponding to the factor exp( — Gi/RT) for each state of free energy Gi (see Moelwyn-Hughes, 1961), and one appreciates that each molecule within a population of molecules will in time explore the vast ensemble of possible structural states.
TL;DR: Form II of the Patient Satisfaction Questionnaire (PSQ), a self-administered survey instrument designed for use in general population studies, well represents the content of characteristics of providers and services described most often in the literature and in response to open-ended questions.
Posted Content•
TL;DR: In this paper, the authors model the negative self-characterizations of welfare recipients as a form of social stigma, and use a utility maximization model to predict the impact of welfare programs on the low-income population.
Abstract: Perhaps the most basic assumption of the economic theory of consumer demand is that "more is better than less." Virtually all of the major propositions of consumer theory can, in a certain sense, be derived from the assumption that "goods are good." Interestingly, however, this tenet seems to be violated by the behavior of many individuals in the low-income population, for many turn out to be eligible for a positive welfare benefit but do not in fact join the welfare rolls. For example, it has been estimated that in 1970, only about 69 percent of the families eligible for AFDC (Aid to Families with Dependent Children) participated in the program (see Richard Michel, 1980). The corresponding percentage for AFDC-U, the program for which families with an unemployed male are eligible, was only 43 percent and the participation rate in the Food Stamp Program was only 38 percent (see Maurice McDonald, 1977). This phenomenon has puzzled many investigators because such individuals do not locate on the boundaries of their budget sets. Consequently, most investigators ignore the problem when studying the effects of welfare programs on behavior. In this paper, this seemingly irrational rejection of an increase in income is modeled as resulting from welfare stigma -that is, from disutility arising from participation in a welfare program per se.1 The existence of stigma has been amply documented in the sociological literature (Patrick Horan and Patricia Austin, 1974; Lee Rainwater, 1979), where interviews of recipients have often uncovered feelings of lack of self-respect and " negative self-characterizations" from participation in welfare. Nevertheless, this phenomenon has not been modeled, and many questions consequently remain. When is the disutility of participation strong enough to prevent participation? Shouldn't we expect individuals to weigh the disutility of participation against the potential benefit in their decisions? What is the elasticity of participation with respect to the potential benefit? Also, in a slightly different vein, how are the work disincentives of welfare affected by stigma? These questions have been given scant attention by economists, yet they are crucial for our ability to predict the impact of various welfare programs on the lowincome population. Here these questions are addressed by modeling nonparticipation as a utility-maximizing decision. The model is developed and estimated for the AFDC program.2 The model posits an individual utility function containing not just disposable income, but
Book•
01 Jan 1983
TL;DR: In this article, the authors present a set of model life tables and stable populations with a variety of associated parameters including the age distributions of deaths, which are used for a wide range of demographic analysis and estimation of population statistics.
Abstract: The intention of this volume is to make available to demographers and statisticians extended tabulations that will expedite a wide range of demographic analysis and estimation of population statistics. The tables presented are of 2 principal types: model life tables and stable populations. This volume makes available a set of model life tables somewhat different and more extensive than the United Nations collection and a large number--almost 5000--of stable populations with a variety of associated parameters including the age distributions of deaths. The 3 chapters of the introductory text present a general description of model life tables and stable populations a brief account of the methods of calculation used to construct the tables and illustrative uses of the tables and explanations of the terms and symbols employed. The life tables presented were calculated on the basis of the joint use of data originating from continuous registration and from an enumeration of the population at a given time. A basic collection was obtained containing 326 male and 326 female life tables. The 4 families of life tables presented in this volume are the result of a search for several distinctive patterns in the variation of mortality rates with age. 9 principal sets of correlations were experimented with for each sex: tables before 1870; tables for Russia and certain Balkan areas; tables for selected Central European areas; tables for Scandinavian countries; tables for Spain Portugal and Southern Italy; tables for Switzerland; tables for countries with reliable data and previously not included; tables reflecting mortality when there is an unusually high incidence of tuberculosis; and modern tables based on relatively inaccurate data primarily from Asia Africa and Latin America.
TL;DR: The feasibility of using a shorter version of the Profile of Mood States is examined, indicating the suitability of the short version for estimating the original mood scale scores in this population of cancer patients.
Abstract: The feasibility of using a shorter version of the Profile of Mood States is examined. Eighty-three cancer patients were administered the Profile of Mood States. The scales' internal consistency (coefficient alpha) and the items' face validity were used as criteria for eliminating items. The number of items was reduced from 65 to 37 and the correlation coefficients between the short and original scales were all above .95, indicating the suitability of the short version for estimating the original mood scale scores in this population.
TL;DR: High-voltage electron microscopy after detergent extraction of human epidermal keratinocyte (HK) colonies grown in the defined medium with low and high calcium has revealed specific changes in the intermediate filament network and keratohyalin granules corresponding to changes in cellular differentiation.
TL;DR: By analyzing the hearts of quail-chick chimeras, it was found that neural crest cells at the level of occipital somites 1 to 3 migrate to the region of the aorticopulmonary septum, resulting in common arterial outflow channels or transposition of the great vessels.
Abstract: By analyzing the hearts of quail-chick chimeras, it was found that neural crest cells at the level of occipital somites 1 to 3 migrate to the region of the aorticopulmonary septum. Bilateral removal of this neural crest population prior to migration causes malformation of the aorticopulmonary septum resulting in common arterial outflow channels or transposition of the great vessels.
TL;DR: The association between perceived health ratings ("excellent," "good," "fair," and "poor") and mortality was assessed using the 1965 Human Population Laboratory survey of a random sample of 6928 adults in Alameda County, California, and a subsequent nine-year follow-up.
Abstract: The association between perceived health ratings ("excellent," "good," "fair," and "poor") and mortality was assessed using the 1965 Human Population Laboratory survey of a random sample of 6928 adults in Alameda County, California, and a subsequent nine-year follow-up. Risk of death during this period was significantly associated with perceived health rating in 1965. The age-adjusted relative risk for mortality from all causes for those who perceived their health as poor as compared to excellent was 2.33 for men and 5.10 for women. The association between level of perceived health and mortality persisted in multiple logistic analyses with controls for age, sex, 1965 physical health status, health practices, social network participation, income, education, health relative to age peers, anomy, morale, depression, and happiness.
TL;DR: In this article, the problem of household comparability is abstracted by considering a population of n households, identical in all respects except for their incomes, and the question of ordering social states then becomes one of ranking income distributions over a group of anonymous households or individuals.
Abstract: A large variety of policy questions involve choices between social states and a consequent ordering of the feasible alternatives. When these social states are related to the levels of welfare experienced by individuals or households, two central issues stand out in determining the relative desirability of different social outcomes. One of these is the essentially positive exercise of achieving comparability between households with different characteristics (such as composition or preferences) operating in different environments (for example, facing different price structures). The other concerns the normative judgments implicit in the evaluation of alternative allocations of resourcesthe emphasis placed on inequality between households and the extent to which greater inequality can be compensated by higher average living standards. This paper focuses on the second of these issues, and in doing so we abstract from the problem of household comparability by considering a population of n households, identical in all respects except for their incomes.' The question of ordering social states then becomes one of ranking income distributions over a group of anonymous households or individuals. Borrowing the usual assumptions imposed on consumer preferences, we may suppose that a social ordering of income distributions can be represented by a "welfare function"2
TL;DR: For example, the authors found that Hispanic men have lower average wage rates than white non-Hispanics, due to age and education, geographic location, immigration, language difficulties, and discrimination.
Abstract: H ISPANIC American men have lower average wage rates than white non-Hispanics. In 1975 the average white non-Hispanic male wage-earner in the United States earned $5.97 an hour. Mexican men earned $4.31, 72% as much as white non-Hispanics; Puerto Rican men earned $4.52, 76% as much; and Cuban men earned $5.33, 89% as much as white non-Hispanics. By way of comparison, black men's average wages in 1975 were $4.65, 78% of the white male wage.' Several possible reasons for the Hispanics' lower wages come to mind. Among them are age and education, geographic location, immigration, language difficulties, and discrimination. For example, as shown in table 1, Mexicans and Puerto Ricans are younger, on average, than the white non-Hispanic population, and earnings tend to rise with age. Hispanics have lower average levels of education than white non-Hispanics, and wages are positively associated with education. Many Mexican Americans live in the Southwest, where prices are relatively low. Moreover, Hispanics are more likely to be recent immigrants and to lack fluency in English than white non-Hispanics, and so to be at a disadvantage in the labor market. In addition, there is a widespread belief that Hispanics suffer from employment discrimination, and cannot obtain the wages that their human capital would command if they were non-Hispanic whites. How much of the wage differentials described above are due to each of these factors, and to other inter-group differences in wage-related characteristics? In particular, how much impact does labor market discrimination have on the average Hispanic man's wage and how does this compare with discrimination against blacks? This paper provides answers to these questions. A few other efforts have been made to analyze the relative earnings of Hispanic and white nonHispanic men, using 1960 and 1970 Census data (Fogel, 1966; Poston and Alvirez, 1973; Poston, Alvirez, and Tienda, 1976; Long, 1977; and Gwartney and Long, 1978). We use more recent data from the 1976 Survey of Income and Education. This data set enables us to measure wage rates more accurately and to specify the wage function more completely than does the Census. Unlike previous analysts, in estimating the wage function we take account of possible selectivity bias due to the distinction between average wage offers and average observed wages. Thus, we hope to obtain a more accurate and up-to-date measure of labor market discrimination against Hispanic men. Section II explains the method used to separate the minority-white non-Hispanic wage differential into the portions due to differences in average characteristics and the portion due to differences in unobserved factors and discrimination, taking into account the possibility of selectivity bias in the observed wage sample. Section III describes the data used in the study and the specification of the wage equation. The breakdown of the observed wage differentials into components due to differences in participation in the wage and salary sector, local price levels, average characteristics, and discrimination are presented in section IV. Section V summarizes our findings and discusses their implications for efforts to improve the economic situation of Hispanics in the United States.
TL;DR: Evidence is presented herein from biochemical, physiological, developmental, and genetical sources which indicates that the nucleotypic effects of chromosome doubling are not necessarily negative, and indeed chromosome doubling may "propel" a population in to a new adaptive sphere, and render it capable of occupying habitats beyond the limits of its diploid progenitor.
Abstract: The role of polyploidy per se in the development of evolutionary novelty remains one of the outstanding questions in flowering plant evolution. Since chromosome doubling usually is associated with hybridization, the effects of doubling are difficult to uncouple from those of hybridity and recombination. Synthetic polyploids in crops typically are inferior to their diploid counterparts under conditions to which the diploids are adapted. This observation has suggested to many that chromosome doubling is a hindrance to progressive evolution. Evidence is presented herein from biochemical, physiological, developmental, and genetical sources which indicates that the nucleotypic effects of chromosome doubling are not necessarily negative. Indeed chromosome doubling may "propel" a population in to a new adaptive sphere, and render it capable of occupying habitats beyond the limits of its diploid progenitor. This postulate is consistent with what we know of the ecological tolerances of diploids and related polyplo...
TL;DR: It is suggested that aneurysmal coronary disease does not represent a distinct clinical entity but is, rather, a variant of coronary atherosclerosis.
Abstract: To examine the clinical and historical features and the natural history of aneurysmal coronary disease, we reviewed the registry data of the Coronary Artery Surgery Study (CASS). Nine hundred seventy-eight patients, representing 4.9% of the total registry population, were identified as having aneurysmal disease. No significant differences were noted between aneurysmal and nonaneurysmal coronary disease patients when features such as hypertension, diabetes, lipid abnormalities, family history, cigarette consumption, incidence of documented myocardial infarction, presence and severity of angina, and presence of peripheral vascular disease were examined. In addition, no difference in 5-year medical survival was noted between these two groups. These findings suggest that aneurysmal coronary disease does not represent a distinct clinical entity but is, rather, a variant of coronary atherosclerosis.
TL;DR: It is concluded that the 3-day activity record is a procedure suitable to estimate energy expenditure in population studies and supports the hypothesis that mean energy expenditure per kg of body weight is significantly correlated with physical working capacity expressed per kgof body weight.
TL;DR: The development of an instrument to measure a range of beliefs potentially important as reasons for not committing suicide and the results indicated that the RFL differentiated suicidal from nonsuicidal individuals in both samples are described.
Abstract: University of Washington Catholic University of AmericaStevan Lars Nielsen and John A. ChilesUniversity of WashingtonThe studies presented here describe the development of an instrument to measurea range of beliefs potentially important as reasons for not committing suicide.Sixty-five individuals generated 72 distinct reasons; these were reduced to 48 byfactor analyses performed on two additional samples, and the items were arrangedinto the Reasons for Living Inventory (RFL), which requires a rating of howimportant each reason would be for living if suicide was contemplated. In ad-dition, factor analyses indicated six primary reasons for living: Survival and Cop-ing Beliefs, Responsibility to Family, Child-Related Concerns, Fear of Suicide,Fear of Social Disapproval, and Moral Objections. The RFL was then given totwo additional samples, 197 Seattle shoppers and 175 psychiatric inpatients. Bothsamples were divided into several suicidal (ideators and parasuicides) and non-suicidal groups. Separate multivariate analyses of variance indicated that the RFLdifferentiated suicidal from nonsuicidal individuals in both samples. In the shop-ping-center sample, the Fear of Suicide scale further differentiated between pre-vious ideators and previous parasuicides. In the clinical sample, the Child-RelatedConcerns scales differentiated between current suicide ideators and current para-suicides. In both samples, the Survival and Coping, the Responsibility to Family,and the Child-Related Concerns scales were most useful in differentiating thegroups. Results were maintained when the effect of recent stress was held constant.The frequency of suicidal behavior sug- point in their lifetime; between 53% and 67%gests that it is a phenomenon that cannot be report seriously considering it.ignored. Over 25,000 individuals a year kill The majority of research in the field ofthemselves in the United States (U.S. Vital suicidology, to date, has been directed atStatistics, 1973, 1975), and it is estimated identifying characteristics of suicidal personsthat two to eight times this number, or from to enhance prediction of suicidal behavior50,000 to 200,000 persons a year parasuicide (Beck, Resnick, & Lettieri, 1974; Kreitman,(i.e., intentionally self-injure, behavior usu- 1977;Neuringer, 1974). With few exceptionsally labeled in the U.S. as attempted suicide; (e.g., Goodstein, 1982) almost all of this workBerman, 1975). Linehan and colleagues (Li- has focused on identifying maladaptive at-nehan & Laffaw, in press; Linehan & Nielsen, tributes of suicidal persons. Little attention1981; Linehan, Note 1) found that from 10% has been given the question of whether sui-to 16% of an adult, general population in cidal persons lack important adaptive char-Seattle report attempting suicide at some acteristics present among nonsuicidal indi-viduals, and, if so, what these characteristicsThis research was supported by National Institute might be.Grant MH34486. Focusing on adaptive, life-maintaining
TL;DR: A series of stages in the development of renal changes in diabetes, characterized by early hyperfunction and hypertrophy, are defined, which may be useful both in clinical work and in research activities.
Abstract: Alterations in renal function and structure are found even at the onset of diabetes mellitus. Studies performed over the last decade now allow definition of a series of stages in the development of renal changes in diabetes. Such a classification may be useful both in clinical work and in research activities. Stage 1 is characterized by early hyperfunction and hypertrophy. These changes are found at diagnosis, before insulin treatment. Increased urinary albumin excretion, aggravated during physical exercise, is also a characteristic finding. Changes are at least partly reversible by insulin treatment. Stage 2 develops silently over many years and is characterized by morphologic lesions without signs of clinical disease. However, kidney function tests and morphometry on biopsy specimens reveal changes. The function is characterized by increased GFR. During good diabetes control, albumin excretion is normal; however, physical exercise unmasks changes in albuminuria not demonstrable in the resting situation. During poor diabetes control albumin excretion goes up both at rest and during exercise. A number of patients continue in stage 2 throughout their lives. Stage 3, incipient diabetic nephropathy, is the forerunner of overt diabetic nephropathy. Its main manifestation is abnormally elevated urinary albumin excretion, as measured by radioimmunoassay. A level higher than the values found in normal subjects but lower than in clinical disease is the main characteristic of this stage, which appeared to be between 15 and 300 micrograms/min in the baseline situation. A slow, gradual increase over the years is a prominent feature in this very decisive phase of renal disease in diabetes when blood pressure is rising. The increased rate in albumin excretion is higher in patients with increased blood pressure. GFR is still supranormal and antihypertensive treatment in this phase is under investigation, using the physical exercise test. Stage 4 is overt diabetic nephropathy, the classic entity characterized by persistent proteinuria (greater than 0.5 g/24 h). When the associated high blood pressure is left untreated, renal function (GFR) declines, the mean fall rate being around 1 ml/min/mo. Long-term antihypertensive treatment reduces the fall rate by about 60% and thus postpones uremia considerably. Stage 5 is end-stage renal failure with uremia due to diabetic nephropathy. As many as 25% of the population presently entering the end-stage renal failure programs in the United States are diabetic. Diabetic nephropathy and diabetic vasculopathy constitute a major medical problem in society today.
TL;DR: A formula is derived for determining the number of observations necessary to test the equality of two survival distributions when concomitant information is incorporated, and this formula should be useful in designing clinical trials with a heterogeneous patient population.
Abstract: A formula is derived for determining the number of observations necessary to test the equality of two survival distributions when concomitant information is incorporated. This formula should be useful in designing clinical trials with a heterogeneous patient population. Schoenfeld (1981, Biometrika 68, 316-319) derived the asymptotic power of a class of statistics used to test the equality of two survival distributions. That result is extended to the case where concomitant information is available for each individual and where the proportional-hazards model holds. The loss of efficiency caused by ignoring concomitant variables is also computed.
Journal Article•
TL;DR: The recovery seen in late pregnancy suggests that the women mount a satisfactory immune response to malaria infection, reacquiring their prepregnancy immune status at about the time of delivery.
Abstract: This article summarizes information and specific evidence regarding the epidemiology of malaria in pregnancy in Africa. Malaria infection is more frequent and severe in primigravidae both during pregnancy and at the time of delivery. A study of pregnant women living under holoendemic conditions in western Kenya showed that the peak prevalence of infection in primigravidae (85.7%) and multigravidae (51.7%) occurred at 13-16 weeks gestation. There were a similar number of recoveries in both groups during the 2nd and 3rd trimesters. The loss of immunity in early pregnancy was equivalent to an 11-fold decrease in the rate of recovery from infection. The recovery seen in late pregnancy suggests that the women mount a satisfactory immune response to malaria infection reacquiring their prepregnancy immune status at about the time of delivery. The pattern of infection in pregnancy is comparable to that observed in infants and children. What the child achieves over several years the mother reachieves in 9 months; the pattern is repeated in successive pregnancies. The practical implications of this pattern of malaria in pregnancy are discussed. (authors modified)
TL;DR: Estimates of health technology must be obtained from a behavioral model in which health inputs are themselves choices, which leads to correlations between inputs and health outcomes that cannot be used to derive causal conclusions.
Abstract: The household production literature emphasizes that technical or biological processes condition input selection by households in their production activities, along with prices and income. Exogenous variations in health, to the extent that they are perceived by individuals (heterogeneity), lead to correlations between inputs and health outcomes that cannot be used to derive causal conclusions. Therefore, estimates of health technology must be obtained from a behavioral model in which health inputs are themselves choices. Consistent estimates are reported of the effect of endogenous inputs, such as medical care, smoking, and fertility, on birth weight and fetal growth in the presence of health heterogeneity.