Showing papers on "Population published in 1976"

A self-assessment questionnaire to determine morningness-eveningness in human circadian rhythms.

Abstract: An English language self-assessment Morningness-Eveningness questionnaire is presented and evaluated against individual differences in the circadian vatiation of oral temperature 48 subjects falling into Morning, Evening and Intermediate type categories regularly took their temperature Circadian peak time were identified from the smoothed temperature curves of each subject Results showed that Morning types and a significantly earlier peak time than Evening types and tended to have a higher daytime temperature and lower post peak temperature The Intermediate type had temperatures between those of the other groups Although no significant differences in sleep lengths were found between the three types, Morning types retired and arose significantly earlier than Evening types Whilst these time significatly correlated with peak time, the questionnaire showed a higher peak time correlation Although sleep habits are an important determinant of peak time there are other contibutory factors, and these appear to be partly covered by the questionnaire Although the questionnaire appears to be valid, further evaluation using a wider subject population is required

Social Indicators of Well-Being: Americans' Perceptions of Life Quality

Abstract: 1: Introduction- Social Indicators- Characteristics of Social Indicators- Quality of Life- Objective and Subjective Indicators- The Research Problem- Research Goals- Usefulness- Basic Concepts and a Conceptual Model- Domains and Criteria- A Conceptual Model- Going Beyond the Model- Dimensional Expansion of the Model- Feedback Loops- Processes That Generate Affective Evaluations- Methods and Data- The Measurement of Affective Evaluations- Data Sources- National-Level Surveys- Local-Level Survey- Summary- 1: Developing Indicators of Perceived Well-Being- 2: Identifying and Mapping Concerns- Research Strategy- Identifying Concerns- Mapping the Concerns- Maps and the Mapping Process- Perceptual Structures-July Respondents- Description of the Structure- Interpretation of Dimensions- Relationships Among Concerns- Perceptual Structures-May and November Respondents- Perceptual Structures-April Respondents- Perceptual Structures-After Equating for Level and Variability of Evaluations- Perceptual Structures-Subgroups of the Population- Men and Women- Four Age Groups- Blacks- Groups with High or Low Status- Selecting and Clustering Concern-Level Measures- Methodology- Clusters- Affective Evaluations Versus Unspecified Feelings- Summary- 3: Measuring Global Well-Being- On the Existence of Global Assessments of Life Quality- The Global Measures and a Typology for Classifying Them- General Assessments of Life-as-a-Whole from an "Absolute" Perspective- Full-Range Measures- Part-Range Measures- More Specific Qualities of Life-as-a-Whole, "Absolute" Perspective- Assessments of Life-as-a-Whole from a Relative Perspective- Assessment of Life-as-a-Whole from the Perspectives of Long- or Short-Term Change- Long-Term Change- Short-Term Change- Supplementary Global Measures- Formal Structure of the Typology- Interrelationships Among Global Measures- Overview of Results- Results from April Respondents- Relationships Among Global Measures- Smallest Space Analysis- Results for Subgroups- Summary of Results from April Respondents- Results from November Respondents- Relationships Among Global Measures- Factor Analysis- Summary of Results from November Respondents- Results from July Respondents- Relationships Among Global Measures- Factor Analysis- Summary- 4: Predicting Global Well-Being: I- Life 3 A Measure of Global Well-Being- Topics to Be Discussed and Overview of Results- Relationships Between Single Concern Measures and Life 3- Multivariate Prediction of Life 3- Models for Predicting Life 3 from Concern Measures- Linearities- Lack of Interactions- Weighting Schemes- Conclusions and Comments About the Prediction Model- Predicting Life 3 Using Different Sets of Concern Measures- Results from May Respondents- Results from November Respondents- Results from April Respondents- Results from July Respondents- Using Classification Variables to Predict Life 3- Results from May Respondents- Results from April Respondents- Lack of Statistical Interactions- Evaluation of Predictive Levels Achieved- May Data- July Data- November and April Data- Prediction of Life 3 in Subgroups of the Population- Summary- 5: Predicting Global Well-Being: II- Plan of the Chapter and Overview of Results- Relationships Between Single Concern Measures and the Global Measures- Type A Global Measures- Type B Global Measures- Type C Global Measures- Type D Global Measures- Type E Global Measures- Type F Global Measures- Type G Global Measures- Comment- Multivariate Prediction of Global Measures- Summary- 6: Evaluating the Measures of Well-Being- Plan of the Chapter and Overview of Results- Estimation of the Validity and Error Components of the Measures- Measurement Theory and Models- Variance Components- Measurement Models- Construct Validity and Measurement Models- Estimates Derived from the July Data- Nature of the July Data- The Measurement Model- The Results- Summary and Comments Regarding July Results- The Reliability of the Life Measures in National Data- Estimates Derived from the May Data- Estimates Derived from the April Data- Estimates Derived from the November Data- Estimates Derived from the October Data- Comparison of Validity Estimates for Different Methods- Distributions Produced by the More Valid Methods- Statistical Results- Conclusions and Comments About Distribution Forms- Overall Evaluations, Additional Criteria, Further Improvements- Category Labeling and Ease of Use- Overall Evaluations- Toward Further Improvements- Relationships Between Measures of Perceived Well-Being and Other Types of Variables- Summary- 7: Exploring the Dynamics of Evaluation- Organization of the Chapter and Summary of Results- Exploration 1: A Statistical Translation Between the Delighted-Terrible Scale and the Faces, Circles, and Ladder Scales- Exploration 2: The D-T Scale Categories and Three More General Levels of Evaluation- Exploration 3: Hypothetical Family Incomes and Affective Evaluations on the D-T Scale- Exploration 4: The Role of Perceptions About the Past and Future in Predicting Present Evaluations- Exploration 5: Six Frames of Reference and Evaluations of Well-Being- Exploration 6: An Implementation of the Domains-by-Criteria Model- The Problem- Design of the Analysis and Measures Employed- Results- Bivariate Relationships- Multivariate Relationships- Conclusions- Exploration 7: Comparisons Between One's Own Well-Being and That of Others- Exploration 8: Judgments of the "Importance" of Concerns- Exploration 9: Searching for People with Distinctive Patterns of Feelings About Well-Being- Summary- 2: Well-Being in the United States: Americans' Perceptions- 8: Americans' Well-Being: Specific Life Concerns- The Nation- The National Government- Local Government- Economic Situation- Community- Services and Facilities- Education- Jobs- Neighborhood- Friends and Associates- Home- Leisure and Leisure-Time Facilities- Family- Self- Interpersonal Relations- Seasonal Changes- Comparisons Among Means- Skewness, Bias, and Spread- Discussion- Summary- 9: Americans' Well-Being: Differences Among Population Groups- Groups Identified- Comparison of General Well-Being in Different Groups- Men and Women- Age Groups- Family Life-Cycle- Socioeconomic Status- Blacks and Whites- Nondifferences- Discussion- Summary- 10: Americans' Well-Being: Life-as-a-Whole- Evaluations of Life-as-a-Whole by the Total Population- General Evaluations of Life-as-a-Whole- Absolute Perspective (Type A and B Measures)- Long-Term Changes in Well-Being (Type E Measures)- Own Well-Being Relative to That of Others (Type D Measures)- More Specific Evaluations of Life-as-a-Whole (Type C Measures)- Satisfaction, Happiness, Worries- Positive Affect, Negative Affect, Affect Balance- Selected Other Qualities of Life-as-a-Whole- Evaluations of Life-as-a-Whole in Population Groups- General Evaluations of Life-as-a-Whole- Absolute Perspective (Type A Measures)- Long-Term Changes in Well-Being (Type E Measures)- Best Week, Worst Week, Short-Term Changes (Measures of Types B and F)- Own Well-Being Relative to That of Others (Type D Measures)- More Specific Evaluations of Life-as-a-Whole (Type C Measures)- Satisfaction- Happiness- Positive and Negative Affect- Affect Balance- Worries- Comments on Defenses, Adaptations, and Coping Mechanisms- Summary- 3: Future Applications- 11: Applications- Organization of the Chapter- Instrument Design- Parameters Affecting Instrument Design- Substantive Interests- Resources- Precision- Methods of Data Collection- Specific Proposals on Instrument Design- Concern-Level Measures- Global Measures- Response Scales- Analysis and Interpretation- Measure Construction and Analysis- Interpretation Perspectives- Summary- Appendixes- Appendix A: Interview and Questionnaire Schedules- Interview Used with May Respondents- Interview Used with November Form 1 Respondents- Interview Used with November Form 2 Respondents- Interview Used with April Respondents- Questionnaire Used with July Respondents- Appendix B: Sampling Designs, Response Rates, Sampling Precision- Appendix C: Clusters of Concern Items- Appendix D: Interrelationships Among Concern Items in May and April Surveys, by Population Subgroups- Appendix E: Factor Analyses of Concern Items from May, November, and April National Surveys- Appendix F: Factor Analysis of Global Measures from the April National Survey- Appendix G: Scan for Interactions Involving Concern Measures and Life 3- Appendix H: Demographic Characteristics of July Respondents- Appendix I: Distributions Produced by the Delighted-Terrible, Faces, and Circles Scales on Five Concerns- Appendix J: Number of Cases Used in Computing Means Shown in Exhibit 71- Appendix L: Formation of Socioeconomic Status Scale- Appendix M: Subgroup Ns and Percentage Distributions- Appendix N: Perceived Well-Being in 1974, 1976- References

Establishment and characterization of a human histiocytic lymphoma cell line (U‐937)

Abstract: A human hematopoietic cell line (U-937) with exceptional characteristics was derived from a patient with generalized histiocytic lymphoma. The morphology of the cell line was identical to that of the tumor cells in the pleural effusion from which the line was derived. Since Epstein-Barr virus (EBV) carrying diploid lymphoblastoid cell lines unrelated to the tumor population often become established in vitro from non-Burkitt lymphoma explants, several parameters were studied to discriminate the U-937 from such lines: morphology in vitro, growth characteristics, cytochemistry, surface receptor pattern, Ig production, lysozyme production, beta2-microglobulin production, presence of EBV genome and karyotype. In all these respects U-937 differed from prototype lymphoblastoid cell lines. The histiocytic origin of the cell line was shown by its capacity for lysozyme production and the strong esterase activity (naphtol AS-D acetate esterase inhibited by NaF) of the cells. It is therefore concluded that the U-937 is a neoplastic, histiocytic cell line.

Single-channel currents recorded from membrane of denervated frog muscle fibres

Abstract: THE ionic channel associated with the acetylcholine (ACh) receptor at the neuromuscular junction of skeletal muscle fibres is probably the best described channel in biological membranes. Nevertheless, the properties of individual channels are still unknown, as previous studies were concerned with average population properties. Macroscopic conductance fluctuations occurring in the presence of ACh were analysed to provide estimates for single channel conductance and mean open times1–3. The values obtained, however, depended on assumptions about the shape of the elementary conductance contribution—for example, that the elementary contribution is a square pulse-like event2. Clearly, it would be of great interest to refine techniques of conductance measurement in order to resolve discrete changes in conductance which are expected to occur when single channels open or close. This has not been possible so far because of excessive extraneous background noise. We report on a more sensitive method of conductance measurement, which, in appropriate conditions, reveals discrete changes in conductance that show many of the features that have been postulated for single ionic channels.

Derivation of specific antibody-producing tissue culture and tumor lines by cell fusion

Abstract: Cell fusion techniques have been used to produce hybrids between myeloma cells and antibody-producing cells. The hybrid lines derived are permanently adapted to grow in tissue culture and are capable of inducing antibody-producing tumors in mice. Spleens from mice immunized against sheep red blood cells (SRBC) were fused to an 8-azaguanine-resistant clone (X63-Ag8) of MOPC 21 myeloma. Over 50% of the derived hybrid lines produce and secrete immunoglobulins different from the MOPC 21 myeloma. About 10% of the hybrid lines exhibit anti-SRBC activity. The high proportion of antibody-producing hybrids suggests that the fusion involves a restricted fraction of the spleen cell population, probably cells committed to antibody production. In order to avoid the presence of the MOPC 21 heavy chain in the specific hybrids, another myeloma cell line (NSI/1-Ag4-1) has been used. This is a nonsecreting variant of the MOPC 21 myeloma which does not express heavy chains. Three anti-SRBC (probably of the mu, gamma2b and gamma1 classes, respectively) and two anti-2,4,6-trinitrophenyl (of the mu class) antibody-producing hybrids have been repeatedly cloned. By random selection and by selection of specific clones according to their lytic activity (clone plaque selection), a number of different lines have been constructed. Such lines express different combinations of the four possible chains of each hybrid line: the myeloma gamma and K chains and the specific antibody heavy and light chains. In three cases (Sp1, Sp2 and Sp7) it is shown that only the specific H and L combination has activity and that the myeloma chains are unable to substitute for them. In most cases lines have been derived which no longer express the MOPC 21 chains but only the specific antibody chains.

Design and analysis of randomized clinical trials requiring prolonged observation of each patient. I. Introduction and design.

Abstract: The Medical Research Council has for some years encouraged collaborative clinical trials in leukaemia and other cancers, reporting the results in the medical literature. One unreported result which deserves such publication is the development of the expertise to design and analyse such trials. This report was prepared by a group of British and American statisticians, but it is intended for people without any statistical expertise. Part I, which appears in this issue, discusses the design of such trials; Part II, which will appear separately in the January 1977 issue of the Journal, gives full instructions for the statistical analysis of such trials by means of life tables and the logrank test, including a worked example, and discusses the interpretation of trial results, including brief reports of 2 particular trials. Both parts of this report are relevant to all clinical trials which study time to death, and wound be equally relevant to clinical trials which study time to other particular classes of untoward event: first stroke, perhaps, or first relapse, metastasis, disease recurrence, thrombosis, transplant rejection, or death from a particular cause. Part I, in this issue, collects together ideas that have mostly already appeared in the medical literature, but Part II, next month, is the first simple account yet published for non-statistical physicians of how to analyse efficiently data from clinical trials of survival duration. Such trials include the majority of all clinical trials of cancer therapy; in cancer trials,however, it may be preferable to use these statistical methods to study time to local recurrence of tumour, or to study time to detectable metastatic spread, in addition to studying total survival. Solid tumours can be staged at diagnosis; if this, or any other available information in some other disease is an important determinant of outcome, it can be used to make the overall logrank test for the whole heterogeneous trial population more sensitive, and more intuitively satisfactory, for it will then only be necessary to compare like with like, and not, by chance, Stage I with Stage III.

Social Structure from Multiple Networks. I. Blockmodels of Roles and Positions

Abstract: Networks of several distinct types of social tie are aggregated by a dual model that partitions a population while simultaneously identifying patterns of relations. Concepts and algorithms are demonstrated in five case studies involving up to 100 persons and up to eight types of tie, over as many as 15 time periods. In each case the model identifies a concrete social structure. Role and position concepts are then identified and interpreted in terms of these new models of concrete social structure. Part II, to be published in the May issue of this Journal (Boorman and White 1976), will show how the operational meaning of role structures in small populations can be generated from the sociometric blockmodels of Part I.

Natural selection and random genetic drift in phenotypic evolution.

Abstract: In discussions of the major features of evolution, Simpson (1953) applied population genetic models to the interpretation of the fossil record Most population genetics theory concentrates on details of the genetic system, such as gene frequencies and recombination rates, which cannot be directly observed or inferred from measurements on polygenic characters Analysis of phenotypic data, particularly fossil material, requires models which are framed as much as possible in phenotypic terms Starting from a simple formula of quantitative genetics, the methods of population genetics are used here to make a theory of the evolution of the average phenotype in a population by natural selection and random genetic drift By analogy with Wright's (1931) adaptive topography for genotypes, Simpson (1953) proposed the concept of adaptive zones for phenotypes This is an intuitive method of visualizing the dynamics of phenotypic evolution in terms of the degree of adaptation of the various phenotypes in a population, it usually being thought that natural selection increases adaptation Such qualitative ideas are used by most evolutionary biologists and the notion of adaptive zones is popular among paleontologists In the present paper, the concept of adaptive zones is clarified by the construction of an adaptive topography for the average phenotype in a population This shows that with constant fitnesses the average phenotype evolves toward the nearest adaptive zone in the phenotype space But if fitnesses are frequency-dependent the average phenotype may evolve away from an adaptive zone A method is developed for estimating the minimum selective mortality necessary to produce an observed rate of evolution In examples of the evolution of tooth characters in Tertiary mammals, these minimum selective mortalities are found to be exceedingly small In his paper on the measurement of rates of evolution, Haldane (1949) stated that "The slowness of the rate of change makes it clear that agencies other than natural selection cannot be neglected because they are extremely slow by laboratory standards or even undetectable during a human lifetime" He briefly discussed mutation pressure Random genetic drift due to finite population size is another such agency The relative importance of natural selection and random genetic drift has been debated since Wright (1931, 1932) proposed that evolution is a stochastic process Fisher (1958), for example, believed that random genetic drift is insignificant in relation to natural selection The debate continues today at a more biochemical level (Lewontin, 1974) In order to objectively evaluate the role of random genetic drift in macro-evolutionary events, it is necessary to use mathematical models to determine the rate of evolution which can occur by repeated samplings of genetic material in a finite population This paper presents a statistical test for the hypothesis of evolution by random genetic drift, contingent on the effective population size In examples from the fossil record, it is found that rates of evolution equal to or greater than those observed have a significant probability of occurring by random genetic drift

Chromosomal subunits in active genes have an altered conformation

Abstract: Ten percent digestion of isolated nuclei by pancreatic deoxyribonuclease I preferentially removes globin DNA sequences from nuclei obtained from chick red blood cells but not from nuclei obtained from fibroblasts, from brain, or from a population of red blood cell precursors. Moreover, the nontranscribed ovalbumin sequences in nuclei isolated from red blood cells and fibroblasts are retained after mild deoxyribonuclease I digestion. This suggests that active genes are preferentially digested by deoxyribonuclease I. In contrast, treatment of red cell nuclei with staphylococcal nuclease results in no preferential digestion of active globin genes. When the 11S monomers obtained after staphylococcal nuclease digestion of nuclei are then digested with deoxyribonuclease I, the active globin genes are again preferentially digested. The results indicate that active genes are probably associated with histones in a subunit conformation in which the associated DNA is particularly sensitive to digestion by deoxyribonuclease I.

An epidemiology of disability among adults in the United States.

Abstract: This paper presents the findings of an epidemiological analysis of disability among adults in the noninstitutionalized continental United States population. Data were collected through interviews with a probability sample of persons 18 and over, yielding 6,493 completed schedules comprising 80.3 percent of the sample. Distinctions were made among concepts and indicators of pathology, impairment, individual performance, and social performance. Central to the analysis were two dimensions of individual performance (physical and emotional) and two dimensions of disability in social performance (work and independent living). A number of socio-demographic characteristics were included in the analysis. The results show the relative contributions of pathology and impairment to performance on the individual level, and the relative contributions of all of these factors on social performance, that is, the two dimensions of disability. Through pathology, impairment, performance at the individual level, and the socio-demographic characteristics, it was possible to account for 38 percent of the variance in work disability and 74 percent of dependence-independence in community living. Further explanations are given for variance in work disability. Estimates of the size of populations reporting varying types and severities of disability are also presented.

Bifurcations and Dynamic Complexity in Simple Ecological Models

Abstract: Many biological populations breed seasonally and have nonoverlapping generations, so that their dynamics are described by first-order difference equations, Nt+1 = F (Nt). In many cases, F(N) as a function of N will have a hump. We show, very generally, that as such a hump steepens, the dynamics goes from a stable point, to a bifurcating hierarchy of stable cycles of period 2n, into a region of chaotic behavior where the population exhibits an apparently random sequence of "outbreaks" followed by "crashes." We give a detailed account of the underlying mathematics of this process and review other situations (in two- and higher dimensional systems, or in differential equation systems) where apparently random dynamics can arise from bifurcation processes. This complicated behavior, in simple deterministic models, can have disturbing implications for the analysis and interpretation of biological data.

Host selection by insect parasitoids

Abstract: Insects that are parasitic only during their immature stages are termed protelean parasites (11). The protelean parasites that attack invertebrates nearly always de­ stroy their hosts. These parasites are often described as parasitoids, a term coined by Reuter (167) to differentiate them from the typical parasites. Parasitoids include a vast number of species of the so-called parasitic Hymenoptera, the Strepsiptera, and a few of the Diptera, primarily in the family Tachinidae. Although there are a few exceptions, insect parasitoids appear as typical parasites during their early developmental stages and later destroy the host to live as free adults. Placing emphasis on the latter aspects of their feeding behavior, Flanders (62) has recently referred to such insects as carniveroids. The evolutionary strategy of the parasitoid­ host relationship is different from that of either the predator or the parasite-host relationship in that the host's future development is of importance only to the parasitoid (226). The adult female parasitoid upon emergence is often in an alien habitat and removed from a host population. She must locate a suitable host in order to propa­ gate. Salt (179) concluded that the parasitoid first seeks a suitable environment. Laing (109) divided the host selection process into environmental and host factors and believed that the parasitoid is guided to a host habitat by chemical and physical parameters. Once a female has located a host habitat, she then searches systemat­ ically. Combining the information of Salt (179) and Flanders (60), Doutt (41) divided the process that results in successful parasitism into four steps: (a) host habitat location, (b) host location, (c) host acceptance, and (d) host suitability. More recently, a fifth step, host regulation, has been added (226) in order to adequately describe the factors necessary for successful parasitism. The first three of these steps can be combined as aspects of the host selection process. The host selection process may consist of only two or three steps in one relationship or of many steps in others. Because of this, there is often some overlap in describing and

Selective activation of mesocortical DA system by stress.

Abstract: IT is now well established that an important system of dopaminergic (DA) neurones innervates various parts of the cerebral cortex in the rat and other species1–3. In contrast to noradrenergic (NA) terminals which are widely distributed in this structure, the DA terminals are mainly confined to deep layers, particularly in the frontal, the cingular and the entorhinal areas4,5. The results of lesion studies demonstrated that the terminal endings in the frontal cortex originate from the A10 group of DA cell bodies localised in the mesencephalon6–8. This group also contains the cell bodies of the classical mesolimbic DA system projecting to the tuberculum olfactorium, the nucleus accumbens, the nucleus of the stria terminalis, and the amydgala9. The DA terminals found in the cingulate and entorhinal areas of cortex may originate mainly from the A9 group of DA neurones6–8. This group gives rise to the well known nigrostriatal DA system which is implicated in extrapyramidal processes. Its degeneration is in part responsible for some of the symptoms seen in Parkinsonian patients. Little is yet known about the functions of the mesocortical and mesolimbic DA pathways. Electrocoagulation or 6-hydroxydopamine (6-OHDA)-induced lesions of the ventral tegmental area, containing the A10 group, produce a syndrome characterised by “locomotor hyperactivity, serious impairment in tests requiring inhibition of a previously learned response, facilitation of approach learning and of active avoidance and hypoemotivity”10,11. Various workers have suggested that the antipsychotic effects of neuroleptics are in part related to the blockade of postsynaptic DA receptors localised in areas innervated by the mesolimbic and mesocortical DA systems12,13. It seems important to establish whether neurones of these two DA systems correspond to an homogeneous population of cells with similar functional characteristics. We have therefore explored this problem in the rat by examining the reactivity of the mesocortical and mesolimbic DA pathways as well as that of nigrostriatal DA system to stress induced by electric foot shocks. Our results suggest that the mesocortical DA system is selectively activated by this stress.

Population Responses to Patchy Environments

Abstract: discon­ tinuities on many scales in time and space. The patterns of these discontinuities produce an environmental patchwork which exerts powerful influences on the distri­ butions of organisms, their interactions, and their adaptations. Consideration of this environmental patch structure is critical to both the theory and management of populations. Despite the obvious heterogeneity of natural sys­ te.ms, most of the models that form the theoretical fabric of population biology and ecology (and that are increasingly conditioning our perception of reality) tell mathe­ matical stories of populations

The maximal expiratory flow-volume curve. Normal standards, variability, and effects of age.

Abstract: From a randomly selected population representative of the white population of Tucson, Ariz, satisfactory flow-volume data were obtained for 3,115 persons Data from the 746 subjects who were totally free of symptoms or history of cardiorespiratory disease and who had never smoked were used in determining "normal" prediction equations for spirometric parameters and maximal expiratory flows The maximal expiratory flow-volume curve showed considerable intersubject variability, but little change in shape of the mean maximal expiratory flow-volume curve was seen with advancing age when the effects of disease, insult, or injury were excluded

Toward a restatement of demographic transition theory.

Abstract: Interpretations of past population movements and expectations about future trends rest primarily on the "demographic transition theory". However over the years there has been a failure to update the theory. Subsequently researchers have tended to obscure the important distinction between the origins of fertility decline and the demographic history of societies experiencing such decline. This paper argues that an inadequate understanding of how birth levels first begin to fall has led to a premature gloom about the success of family planning programs and unnecessary hysteria about the likely long-term size of the human population and to antagonisms between countries at different stages of demographic transition. It is the contention of this paper that there are only two fertility regimes: one in which there is no economic gain to individuals from restricting fertility and one in which there is economic gain from such transition. Furthermore the author posits that the transition of a society from one with economically unrestricted fertility to one with economically restricted fertility is a product of social change. The forces sustaining economically unrestricted fertility are strengthened by economic modernization accompanied by specific types of social change. Three types of societies are discussed: primitive traditional and transitional societies. Lastly the author maintains that unlimited fertility eventually crumbles in transitional societies and such crumbling as well as its preconditions is unrelated to reductions in family size subsequently occurring in transitional societies.

Localization of factors controlling spermatogenesis in the nonfluorescent portion of the human Y chromosome long arm.

Abstract: A deletion of the Y chromosome at the distal portion of band q11 was found in 6 men with normal male habitus but with azoospermia. Five of them were found during a survey of 1170 subfertile males while the sixth was karyotyped because of slight bone abnormalities. These findings, together with a review of the literature, suggest that on the distal portion of the nonfluorescent segment of the long arm of the Y, factors are located controlling spermatogenesis.

Measuring the quality of medical care. A clinical method.

Abstract: We outline the implementation of a new method of measuring the quality of medical care that counts cases of unnecessary disease and disability and unnecessary untimely deaths. First of all, conditions are listed in which the occurrence of a single case of disease or disability or a single untimely death would justify asking, "Why did it happen?" Secondly, we have selected conditions in which critical increases in rates of disease, disability, or untimely death could serve as indexes of the quality of care. Finally, broad categories of illness are noted in which redefinition and intensive study might reveal characteristics that could serve as indexes of health. We describe how these inth of the general population and the effects of economic, political, and other environmental factors upon it, and to evaluate the quality of medical care provided both within and without the hospital to maintain health and to prevent and treat disease.

Serum lipoproteins and coronary heart disease in a population study of Hawaii Japanese men.

Abstract: To ascertain the frequency of defined hyperlipoproteinemia and to investigate the relation between lipoprotein fractions and coronary heart disease, we measured serum lipoprotein cholesterol levels in a population-based sample of Hawaii Japanese men 50 to 72 years old. Type II hyperlipoproteinemia was present in 3 per cent of 1859 men, and Type IV in 26 per cent. Relative risks for coronary heart disease, based on 264 prevalence cases, were found to be 1.8, 1.8 and 0.46, between the upper and lower quartiles of total, beta, and alpha cholesterol, respectively. We found no significant relation between triglyceride and coronary heart disease. The inverse relation of alpha cholesterol of prevalence of coronary heart disease was independent of beta cholesterol, obesity, and other factors. The data suggest the need for further evaluation of the protective effect of the alpha lipoprotein fraction on the development of coronary heart disease.

Cells of origin of entorhinal cortical afferents to the hippocampus and fascia dentata of the rat

Abstract: The pathway from the entorhinal cortical region to the hippocampal formation has previously been shown to be comprised of two sub-systems, one of which projects predominantly to the ipsilateral fascia dentata and regio inferior of the hippocampus proper, and a second which projects bilaterally to regio superior. The goal of the present investigation was to determine if these two pathways might originate from different cell populations within the entorhinal area. The cells of origin of these entorhinal pathways were identified by retrograde labeling with horseradish peroxidase (HRP). Injections which labeled the entorhinal terminal fields in both the fascia dentata and regio superior resulted in the retrograde labeling of two populations of cells in the entorhinal area. Ipsilateral to the injection, HRP reaction product was found in the cells of layer II (predominantly stellate cells) and the cells of layer III (predominantly pyramidal cells). Contralateral to the injections, however, the reaction product was found almost exclusively in the cells of layer III. With selective injections of the entorhinal terminal field in regio superior, only the cells of layer III were labeled, but these were labeled bilaterally. Selective injection of the entorhinal terminal field in the fascia dentata, however, resulted in the labeling of cells of layer II, but not of layer III, and these cells of layer II were labeled almost exclusively ipsilaterally. A very small number of labeled cells in layer II were, however, found contralateral to the injection as well. No labeled cells were found either in the presubiculum or parasubiculum following injections of the hippocampal formation. These cell populations were found capable of retrograde transport of HRP, however, since cells in both presubiculum and parasubiculum were labeled following HRP injections into the contralateral entorhinal area. These results suggest that the projections to the fascia dentata originate from the cells of layer II, while the projections to regio superior originate from the cells of layer III of the entorhinal region proper. The very slight crossed projection from the entorhinal area to the contralateral area dentata probably originates from the small population of cells in layer II which are labeled following HRP injections in the contralateral area dentata.

New principle for the analysis of chemical carcinogenesis

Abstract: THE development of cancer following exposure to chemical carcinogens or to various forms of irradiation is almost invariably slow and prolonged. Although the process can be initiated by a brief exposure to a carcinogenic stimulus, there is no evidence that target cells so altered are cancer cells. Rather, there is abundant indirect evidence from many systems that what is induced is an altered cell or cell population from which malignant neoplasia can gradually develop or evolve1,2. Neoplastic development therefore resembles a chain reaction, triggered by exposure to a carcinogen, in which the links are new populations with altered organisational, structural and biochemical properties. These slowly proliferative new lesions are characteristically focal in distribution, implying that only a small proportion of the original target cell population in any organ or tissue participates. It is not known what the critical property (or properties) is that makes initiated cells so important in carcinogens and the failure to understand and manipulate this early step has been a major impediment to its analysis.

Precursor cells of mechanocytes.

Abstract: Publisher Summary This chapter discusses precursor cells of mechanocytes. Among the cells of connective tissue, precursors of mechanocytes capable of protracted self-maintenance can be identified by the in vitro colony assay method. They behave as clonogenic cells and give rise to diploid strains of fibroblasts capable of sustained passaging. In cases in which reverse grafting in vivo was carried out, it was found that the differentiation features characteristic of mechanocytes of the source tissue are consistently retained by in vitro descendants of clonogenic cells. Thus self-maintained precursors determined to differentiate into definite types of mechanocytes are present in postnatal life. For clones of mechanocytes from hemopoietic organs a distinguishing property may be the type of inductive microenvironment they create. Beside interorganic differences in the microenvironment, intraorganic ones are obviously present. This is evidenced by the persistence of thymus-dependent and thymus independent zones in lymphoid organs and of regions in the spleen where erythroid colonies occur more frequently than myeloid ones. Stem cell existence has been established unambiguously for tissues with extensive cell renewal. Mechanocytes, on the contrary, have a very slow renewal rate. During the life-span the total number of cell divisions mechanocyte precursors undergo is considerably smaller than that of hemopoietic or lymphoid precursor cells. Therefore it is not excluded that structurally the population of progenitors of mechanocytes will appear fundamentally different as compared to the population of hemopoietic cells.

An Analytic Model for Description of Temperature Dependent Rate Phenomena in Arthropods

Abstract: A new description of temperature-dependent, rate phenomena was deduced to describe developmental time and ovipositional data for the McDaniel spider mite, Tetranychus mcdanieli McGregor. The derived equation accounted for asymmetry about optimum temperature and was of particular utility for description of systems operating at or above optimum temperatures. Ovipositional and developmental rate functions were used in a temperature-driven, discrete-time, simulation model describing McDaniel spider mite population dynamics. Temperature dependence of the instantaneous population growth rate was determined by fitting the derived rate-temperature function to data generated through simulation at various fixed temperatures. The functional relationship of important population parameters to temperature provided the mechanism for inclusion of phenological effects on mite populations in a synoptic apple pest management model. Two derived functions were fit to several published rate-temperature data sets. Adequacy of description (as indicated by R2 values) indicated general applicability of both functions for description of temperature-controlled, biological processes. Further, it was concluded that the singular perturbation method of matched asymptotes has potentially wide application in ecology, and an Appendix detailing the application of this method is included.

Genetic Polymorphism in Heterogeneous Environments

Abstract: The discovery in the last decade, using electrophoresis, of large amounts of genetic polymorphism in natural populations has had a tremendous effect on population genetics. Before then it was not clear how many polymorphic loci there were in a population and the single gene overdominance model generally seemed adequate to explain what polymorphism was documented. In an effort to explain the new-found genetic variation, two opposing camps surfaced in the late 1960s and still exist to some extent today. One group, often called neutralists, believes that most allozymic variants have a minimal effect on fitness and are in a population because of a combination of mutation, finite population size, and migration. In other words, in their view, selection plays little or no role in maintaining different electrophoretic alleles. The other group, sometimes known as selectionists, believes that some sort of balancing selection is responsible for the maintenance of the majority of electropho­ retic alleles. "Balancing selection" is a catch all term for any type of selection that can maintain a stable polymorphism. Among the types of balancing selection that are thought to play a significant role in maintaining genetic polymorphisms are the classical overdominance mode, frequency-dependent selection [see (8) for a recent review], differential selection between the two sexes or between different life stages, and variable selection in time and/or space. This last type of balancing selection is examined here in an effort to understand the importance of selection varying in time and/or space in maintaining genetic polymQrphisms. A significant body of literature demonstrates an association between the genetic attributes of a population and some aspect of the environment. Since much of this material has been reviewed elsewhere (2, 16,58, 165), we concentrate on two of the

Physiology of Peripheral Neurons Innervating Otolith Organs of the Squirrel Monkey. I. Response to Static Tilts and to Long-Duration Centrifugal Force

Abstract: 1. The response to static tilts was studied in peripheral otolith neurons in the barbiturate-anesthetized squirrel monkey (Saimiri sciureus). Each unit was characterized by a functional polarization vector, which defines the axis of greatest sensitivity. A circumstantial criterion was used to assign units to the inferior (IN) or superior (SN) vestibular nerves. The former neurons should innervate the sacculus, the latter mainly the utriculus. Confirming pasting experiments, the polarization vectors for SN units lay near the plane of the utricular macula, those for IN units near the plane of the saccular macula. The polarization vectors for IN units were compared in two groups of animals. In one group, the vestibular nerve was intact; in the other, the superior nerve was sectioned. No differences were found and this, together with other observations, demonstrate that the sacculas in mammals functions mainly (if not solely) as an equilibrium organ. 2. The resting discharge of otolith neurons averages some 60 spikes/s, the sensitivity some 30-40 spikes/s-g. IN units tend to have slightly lower sensitivities than do SN units. IN units with upwardly directed (+Z) vectors have substantially higher resting discharges than do units with downwardly directed (-Z) vectors. The +Z units are also characterized by more linear force-response relations. 3. There is a strong positive relation between the resting discharge and sensitivity of units characterized by regular steady-state discharge patterns. A weaker, but statistically significant, relation is demonstrable for irregular units. It is suggested that the relation seen in regular units is the result of the neurons differing from one anothrer in terms of a receptor bias, a transduction gain, or both. Only the mechanism based on transduction gain is thought to be operative among the population of irregular units. 4. Centrifugal-force trapezoids were used to study the response adaptation to prolonged stimulation. Adaptation was more conspicious in irregular units and was characterized by perstimulus response declines and poststimulus secondary responses. For regular units, adaptive properties were similar during excitatory and inhibitory responses. For irregular units, response declines were larger during excitatory stimuli, secondary responses larger following inhibitory stimuli. Typically, response declines were most rapid at the start of the force plateau. A few units, all of them irregular, exhibited a delayed adaptation with response declines beginning only after a constant force had been maintained for 10-20 s. 5. Excitatory responses of regular units are almost always larger than inhibitory responses. This is so during both the dynamic and static portions of force trapezoids. A similar asymmetry is seen in the dynamic response of irregular units; static response asymmetries of the latter units are more variable.

Standardized mortality ratios and the "healthy worker effect": Scratching beneath the surface.

Abstract: The age-standardized mortality ratio (SMR) is a relative index of mortality, expressing the mortality experience of the study population relative to that of a comparison ("standard") population. With the general population as the "standard", the SMR for an occupational population will underestimate the mortality experience of that latter population (since it comprises individuals necessarily healthy enough to be employable --and whose mortality risk is therefore initially lower than the general population average). However, this "healthy worker effect" does not equally to all groups within the study population. Therefore, if one attempts to adjust for this effect, the summary nature of the SMR must be recognized, and allowance must be made for variation in the healthy worker effect between different age groups, different races, different work-status groups, different causes of death, and different elapsed-time periods of observation.

Regulation of HMG-CoA Reductase

Abstract: Publisher Summary This chapter discusses the regulation of HMG-CoA reductase, which catalyzes the rate-limiting reaction of hepatic sterol synthesis. Both mitochondrial and extramitochondrial forms of acetoacetyl-CoA thiolase and the HMG-CoA synthase are present in liver tissue. The reductase activity of cultured mammalian cells or of bacteria is readily assayed in crude homogenates. The HMG-CoA reductase activity may be readily assayed in the post-mitochondrial supernatant fraction obtained by high-speed centrifugation of homogenates of tissues, including liver. The chapter also discusses familial hypercholesterolemia (FH), which is an autosomal, dominant genetic disorder estimated to affect 0.1–0.2% of the population. FH may involve defects in the regulation of both cholesterol synthesis and degradation. The data for adults heterozygous for FH indicate that the rate of cholesterol synthesis in vivo is subnormal. The basic defect in FH may be a low affinity of the cellular plasma membrane for cholesterol. This defect, observed in fibroblasts and leukocytes, leads to an impaired uptake of cholesterol from serum lipoproteins and an enhanced release of cellular cholesterol. If this defect is present in the liver, it could account for the relatively ineffective feedback suppression of cholesterol synthesis.