Procedures in the biochemical estimation of age of vertebrates

Summary The most accurate method known to data for estimating age of wild vertebrates involves biochemical assay of eye lens proteins. Laboratory procedures that may be unfamiliar to many ecologists are described in detail. The method is based on precise changes in the amount of insoluble lens protein, and consists of two procedures: obtaining the appropriate lens fraction, and quantitatively analyzing its protein composition. Lenses are homogenized, and the insoluble fraction isolated by centrifugation. Protein content is measured colorimetrically by using the Lowry test. Instructions are given for single and double-beam spectrophotometers.     

Seasonality of coitus and seasonality of birth

Seasonal variation of birth rates has been observed in every population in which it has been studied. Many hypotheses have been advanced to account for the variation, including seasonal variation in frequency of coitus. This relationship is known to be true for other primates, but seasonal variation in coital rate has not been previously documented in man.This paper presents over one hundred woman-years of data on coital rates from about .fifty white, mostly well-educated, premenopausal, married, husband-present volunteers. Seasonal fluctuations were seen in coital rates, of about the same magnitude as seasonal variations in the white birth rates reported for New York City, 1962-64; for the United States, 1963; and for the highest socioeconomic quintile census tracts, Baltimore, 1952-56. However, shifting the birth rates back forty weeks to approximate conception dates revealed no association with the observed coital rates.If the pattern presented has great generality, seasonal variations in births cannot be explained by seasonality of coitus.     

Locational returns to human capital: Minority access to suburban community resources

The suburbanization of racial and ethnic minorities is analyzed in terms of the locational resources provided by their communities of residence. In suburbs in the New York CMSA, non-Hispanic whites and Asians, on average, live in communities with higher average socioeconomic status, while Hispanics and blacks live in the less desirable suburbs. Models predicting suburban socioeconomic status for each racial/ethnic group show that whites and Hispanics receive consistent returns on income, acculturation, and family status. Asians’ locational patterns differ because they are unrelated to measures of acculturation; for blacks, locational outcomes correspond least to any of these human capital characteristics.     

Controlling earth's resources: Markets or socialism?

The important message contained in Garrett Hardin's seminalScience article, "The Tragedy of the Commons," is that in making resource-use decisions individuals see their own narrow interests best and, if not constrained by institutions such as governmental rule or market incentives, will tend to follow those narrow interests. Individuals do not automatically seek to use resources in the long-run best interests of society. This fact of life leads to abuse of resources to which access is not controlled.In this paper, the same insight is applied to the two types of control mechanism cited by Hardin: socialist management and private ownership. Much has been written in the economics literature, especially since "Tragedy" was published, which bears on any comparative analysis of the two systems. Some of these insights are reported here.     

The Influence of Parent and Peer Attachments on Life Satisfaction in Middle Childhood and Early Adolescence

Satisfaction in different life domains wasexamined with respect to parent and peerattachment relationships in middle childhoodand early adolescence. Three hundred threestudents, evenly distributed across sex andgrade (fourth, sixth, and eighth) wereadministered People in My Life, ameasure of attachment relationships, and theMultidimensional Students' LifeSatisfaction Scale. Children and earlyadolescents in this sample generally reportedhigh levels of life satisfaction. Some sex andgrade differences in satisfaction with variouslife domains emerged. Attachments to bothparents and peers predicted life satisfaction,although the influence of these relationshipsvaried as a function of grade level and lifedomain. Findings are reviewed in relation topast research, and implications forprofessional practice are discussed.     

The analysis and measurement of happiness as a sense of well-being

General happiness is philosophically construed as a sense of well-being which in turn has been defined either as a complete and lasting satisfaction with life-as-a-whole or as a preponderance of positive over negative feelings. A factor analysis of thirteen well-being scales shows that these two definitions coalesce into a single general well-being factor which is distinguishable only from an independent stress/worries factor. Further evidence shows that familiar scales of neuroticism, depression and trait anxiety measure the same well-being dimension if only in the negative half-range. So does a list of somatic complaints. Various two-factor models of well-being that treat positive and negative affect as independent processes, or that distinguish between affective and cognitive components, are challenged on the grounds that they depend on the properties of Bradburn's affect scales which are found to be highly dependent on methodological parameters. Attention is drawn here to the role of test method effects and curvilinearities as factors influencing inter-scale correlations and structural models. It is concluded that well-being is a robust, primary dimension of human experience and that happiness research is alive and well in psychology.     

The dimensionality of the urban functional system

This paper suggests that the formulation and testing of hypotheses relating the functional role of cities in a society to other urban structure and process variables might be facilitated by substituting a continuous variable approach to the functional system for the prevailing discrete typologies. Using variables indexing the scope of economic activities in U.S. communities at two points in time, we elaborate a technique for identifying the dimensions underlying an existing typology, and the 56 largest SMSA’s are ranked along these dimensions.     

The difference in unwanted births between blacks and whites

Blacks are more likely than whites to have unwanted births. A common explanation for that difference is that blacks use less effective contraceptive methods, use contraception less effectively, and use contraception less often than whites. Analysis of data from 17 cities in our family planning evaluation project suggested that, among women living in low-income neighborhoods, the black-white difference in unwanted births was not due to (1) blacks reaching desired completed parity at younger ages than whites, (2) differences in age or parity in our black and white samples, (3) black-white differences in current use of physician-administered contraception, or (4) blacks being more likely than whites to adopt physician-administered contraception after having an unwanted birth. Black-white differences which might have contributed to relatively more unwanted births among blacks were (1) blacks desired fewer children, (2) blacks were less likely than whites to use nonphysician-administered methods and more likely than whites to use no contraception, and (3) blacks had higher failure rates than whites subsequent to the adoption of physician-administered methods and when not using those methods. Comparisons are made with the 1965 and 1970 National Fertility Studies, and program implications of the findings discussed.     

Enhancing strength and postocclusive calf blood flow in older people with training with blood-flow restriction

The response of calf-muscle strength, resting blood flow, and postocclusive blood flow (PObf) were investigated after 4 wk of low-load resistance training (LLRT) with and without blood-flow restriction in a matched-leg design. Ten untrained older individuals age 62-73 yr performed unilateral plantar-flexion LLRT at 25% 1-repetition maximum (1RM). One limb was trained with normal blood flow and the other had blood flow restricted using a pressure cuff above the knee. 1RM, isometric maximal voluntary contraction, and isokinetic strength at 0.52 rad/s increased (p < .05) more after LLRT with blood-flow restriction than with normal blood flow. Peak PObf increased (p < .05) after LLRT with blood-flow restriction, compared with no change after LLRT with normal blood flow. These results suggest that 4 wk of LLRT with blood-flow restriction may be beneficial to older individuals to improve strength and blood-flow parameters.