An age‐structured model of population dynamics with dominant ages,delayed behavior,and oscillations

An age‐structured model of population dynamics with age‐dominance is proposed and analyzed. Existence and uniqueness of solutions are established as well as the uniqueness and local asymptotic stability of steady‐states. Conditions for convergence to or oscillation about the steady‐state are specified in some cases.     

The strengths and limitations of demography,and the works of W.D. Borrie

This lecture examines the nature of demography and how the work of W.D. Borrie relates to it. The principal topics are: the meaning of ‘demography’, changes in the discipline, the uniqueness of demography, population theories and ideologies, and the writings of W.D. Borrie.     

Categorization in concentration camps as a collective fate: a comparison of homosexuals, Jehovah's Witnesses and political prisoners

Using socio-historical data some critical features of Nazi Concentration Camps are discussed: uniqueness vs. normality; extermination vs. re-education of gay prisoners. The special fate of the Pink Triangle in comparison to other non-Jewish victims is demonstrated. The determinative qualities of life and death conditions in the camps are: the National Socialist interpretation of the prisoner category; the repressive content of social control; the marginalisation in general society. The relative strength of a single influence cannot be separated one from the other.     

Parental Support for Basic Psychological Needs and Happiness: The Importance of Sense of Uniqueness

Past empirical research relying on self-determination theory (SDT) has consistently shown that parental support of basic psychological needs (BPN) is associated with adolescent happiness. Yet, the specific mechanisms accounting for this link are still undetermined. The present study aimed to address this gap in the literature by testing a theoretical model proposing that adolescents’ satisfaction of BPN in life and sense of uniqueness mediate the association of parental support for BPN and happiness. The analyses relied on structural equation modeling and bootstrapping procedures and found support for the model. The theoretical implications of the model for SDT and applied considerations to improve the well-being of adolescents are discussed. Also, suggestions for future research that could further improve our understanding of the dynamic interplay between BPN, sense of uniqueness and happiness are presented.     

中国的生育率下降:世纪末回顾

本文对近半个世纪以来中国生育率的下降进行了简要总结和分析。通过与发展中地区,尤其是亚洲国家的对比,说明了中国生育率下降的特点;通过不同的生育率指标来刻画中国生育率下降过程的独特性;最后简要阐述了中国生育率下降的因素。     

Determining the birth function for an age structured population

This paper deals with an inverse problem in age-structured population dynamics, namely the recovery of the unknown birth function from the additional or overposed data consisting of the total population over a time interval equal to the maximum life span of the species. Conditions on the data are given to guarantee the existence and uniqueness of a solution, and the question of continuous dependence of the birth function on the data is addressed. Some numerical simulations are presented to indicate that one can, in fact, use the methods of the paper to reconstruct the birth function.     

Determining the initial age distribution for an age structured population

"This paper deals with an inverse problem in age-structured population dynamics; the recovery of an unknown initial age distribution. We attempt to recover this function from overposed data which consists of either the total population over a time interval equal to the maximum life span of the species or the age structure of the population at a fixed later time. Existence, uniqueness and continuous dependence of the initial distribution function on the data are addressed. Some numerical simulations are presented to illustrate the feasibility of recovery using the methods of the paper."     

Convergent and Discriminant Validity of the WHOQOL-BREF Using a Multitrait-Multimethod Approach

The WHOQOL-BREF is a commonly used questionnaire in quality of life research. Previous research has shown that the four domains of the WHOQOL-BREF (physical health, psychological health, social relationships, and environmental health) are highly related. Whether these high correlations reflected the true relations across the domains or the influence of common method effect; however, is still unknown. This study examines the convergent and discriminant validity of the four domains of the WHOQOL-BREF by using the multitrait-multimethod (MTMM) approach to control the method effect. Two different samples, with a total of 186 and 201 adults, respectively, were used in the present study. Each participant filled out the WHOQOL-BREF questionnaires using four different scaling methods (Likert-type scale, visual analogue scale, pie scale, and partner rating). The covariance matrix of the MTMM result was analyzed with confirmatory factor analysis modeling. Two models were applied, including the correlated traits-correlated uniqueness (CTCU) model and the uncorrelated traits-correlated uniqueness (UTCU) model. Results showed that the CTCU model fit the data better than did the UTCU model, suggesting that the variables tapping the four domains of the WHOQOL-BREF have excellent convergent validity; the four domains have moderate correlations, indicating that the four domains are related but not identical.     

Validation Theory and Research for a Population-Level Measure of Children’s Development,Wellbeing, and School Readiness

This paper delineates general validity and research questions that are underlying an ongoing program of research pertaining to the Early Development Instrument (EDI, Janus and Offord 2007), a population-level measure, on which teachers rate kindergarten children’s developmental outcomes in the social, emotional, physical, cognitive, and communicative domains. It describes the large-scale research projects that are using the EDI to measure children’s developmental outcomes for entire populations (e.g., provinces, cities). Given the uniqueness of the EDI’s use as monitoring tool, or social indicator, for children’s developmental health at an early age, we spell out the opportunities and challenges that these projects provide with regard to validation research. The article sets the stage for the special issue, as it is dedicated to showcase the different aspects of the conceptual, theoretical, and empirical validation research as well as the collaborative community-based projects that are currently being undertaken with respect to the EDI.     

Determining the birth function for an age structured population

This paper deals with an inverse problem in age‐structured population dynamics, namely the recovery of the unknown birth function from the additional or overposed data consisting of the total population over a time interval equal to the maximum life span of the species. Conditions on the data are given to guarantee the existence and uniqueness of a solution, and the question of continuous dependence of the birth function on the data is addressed. Some numerical simulations are presented to indicate that one can in fact use the methods of the paper to reconstruct the birth function.     

城市贫困女性权益缺失的制度经济学分析

以国企下岗女工为主体,结合多方面的数据资料以及我国市场经济转轨时期的特殊情况,从劳动力市场、社会网络、社会保障三个方面考察这一群体的权益缺失,并进一步运用新制度经济学的相关理论阐述这些权益的缺失是如何导致她们最终陷入贫困的。对城市贫困女性的忽视会导致对我国家庭稳定与经济发展的危害,应该得到应有的关注。     

The construction and validation of the homopositivity scale: an instrument measuring endorsement of positive stereotypes about gay men

Social scientists appear to focus on negative beliefs about, and attitudes toward, gay men and lesbian women. This emphasis, though understandable in view of the widespread oppression of gay and lesbian individuals, is somewhat myopic because it ignores what might be referred to as the positive dimension of stereotypes. Although such a concept may appear oxymoronic, it is widely recognized that individuals may endorse a mixture of positive and negative stereotypes toward stigmatized groups such as African Americans and women. The purpose of the current series of studies (Study 1, N = 212; Study 2, N = 105) was to devise an instrument measuring endorsement of positive stereotypes about gay men (Homopositivity Scale; HPS). Two versions of the HPS (of varying length) were evaluated, with scale scores on both appearing to be internally consistent and factorially distinct from scales measuring negative stereotypes and prejudices about gay men. These studies also suggest that females are more likely than males to endorse positive stereotypes about gay men, and that such endorsement is negatively associated with need for uniqueness and need for cognition, and positively associated with media contact and benevolent sexism. The limitations of the two studies are outlined and the importance of assessing positive stereotypes about gay men in conjunction with oft-examined homonegativity is discussed.     

A two-sex age-structured population model: well posedness

"In this paper we consider a two-sex population model proposed by Hoppenstead. We do not assume any special form of the mating function. We address the problem of existence and uniqueness of continuous and classical solutions. We give sufficient conditions for continuous solutions to exist globally and we show that they have in fact a directional derivative in the direction of the characteristic lines and satisfy the equations of the model with the directional derivative replacing the partial derivatives. The existence of classical solutions is established with mild assumptions on the vital rates." (EXCERPT)     

Factorial Validity and Invariance of the Rosenberg Self-Esteem Scale Among Portuguese Youngsters

The purpose of the present study was to examine the reliability, factorial validity and measurement invariance (across gender, age and physical activity participation) of a Portuguese version of the Rosenberg Self-Esteem Scale (RSES). The sample consisted of 1,763 Portuguese youngsters (731 male and 1,032 female) with ages between 15 and 20 years. Reliability estimate for the one-factor solution was .845, although some proposed RSES’s underlying dimensions were lower than .70. Confirmatory factor analysis revealed that the best-fitting model was a single self-esteem factor, plus simultaneous correlated uniqueness for positively and negatively worded items. Multigroup analysis supported measurement invariance across age and physical activity participation, and partial metric invariance across gender, as three items failed to show metric equivalence. These results provide evidence that RSES has excellent psychometric properties and it is a valid self-esteem measure to be used among Portuguese youngsters.     

The Population Education Transition Curve: Education Gradients Across Population Exposure to New Health Risks

The salutary effect of formal education on health-risk behaviors and mortality is extensively documented: ceteris paribus, greater educational attainment leads to healthier lives and longevity. Even though the epidemiological evidence has strongly indicated formal education as a leading “social vaccine,” there is intermittent reporting of counter-education gradients for health-risk behavior and associated outcomes for certain populations during specific periods. How can education have both beneficial and harmful effects on health, and under which contexts do particular effects emerge? It is useful to conceptualize the influence of education as a process sensitive to the nature, timing of entry, and uniqueness of a new pleasurable and desirable lifestyle and/or product (such as smoking) with initially unclear health risks for populations. Developed herein is a hypothesis that the education gradient comprises multiple potent pathways (material, psychological, cognitive) by which health-risk behaviors are influenced, and that there can be circumstances under which pathways act in opposite directions or are differentially suppressed and enhanced. We propose the population education transition (PET) curve as a unifying functional form to predict shifting education gradients across the onset and course of a population’s exposure to new health risks and their associated consequences. Then, we estimate PET curves for cases with prior epidemiological evidence of heterogeneous education gradients with health-risk behaviors related to mass-produced cigarettes in China and the United States; saturated fats, sugar, and processed food diets in Latin America; and HIV infection in sub-Saharan Africa. Each offers speculation on interactions between environmental factors during population exposure and education pathways to health-risk behaviors that could be responsible for the temporal dynamics of PET curves. Past epidemiological studies reporting either negative or positive education gradients may not represent contradictory findings as much as come from analyses unintentionally limited to just one part of the PET process. Last, the PET curve formulation offers richer nuances about educational pathways, macro-historical population dynamics, and the fundamental cause of disease paradigm.     

Optimal life-cycle fertility in a Barro-Becker economy

Parenthood postponement is a key demographic trend of the last three decades. In order to rationalize that stylized fact, we extend the canonical model by Barro and Becker (Econometrica 57:481–501, 1989) to include two—instead of one—reproduction periods. We examine how the cost structure of early and late children in terms of time and goods affects the optimal fertility timing. Then, we identify conditions that guarantee the existence and uniqueness of a stationary equilibrium with a stationary cohort size. Finally, we examine how the model can rationalize the observed postponement of births, and we highlight two plausible causes: (1) a general rise in the cost of children in terms of goods and (2) a decline in the degree of family altruism.     

A Critical Examination of the Environmental Mastery Scale

The Psychological well being Inventory (PWBI) is a multidimensional instrument that has enjoyed widespread use in a variety of research initiatives, from small-scale studies to national surveys. Recent empirical investigation of the measure has raised questions about its validity. This study examines the factorial validity of the Environmental Mastery Scale of the PWBI, a construct that receives much attention in mental health research. The results of a confirmatory factor analysis did not support the unidimensional factor structure of the measure. Correlated uniqueness models were also examined, which did not reveal evidence of a method effect. There are problems with the measure at the item level, which also raises significant questions about the underlying theory of its parent measure. This research uses data from the Wisconsin Longitudinal Study (WLS) of the University of Wisconsin-Madison. Since 1991, the WLS has been supported principally by the National Institute on Aging (AG-9775 and AG-21079), with additional support from the Vilas Estate Trust, the National Science Foundation, the Spencer Foundation, and the Graduate School of the University of Wisconsin-Madison. A public use file of data from the Wisconsin Longitudinal Study is available from the Wisconsin Longitudinal Study, University of Wisconsin-Madison, 1180 Observatory Drive, Madison, Wisconsin 53706 and at http://www.ssc.wisc.edu/wls/data/. The opinions expressed herein are those of the authors.     

Explaining cross-national differences in marriage, cohabitation, and divorce in Europe, 1990-2000

European countries differ considerably in their marriage patterns. The study presented in this paper describes these differences for the 1990s and attempts to explain them from a macro-level perspective. We find that different indicators of marriage (i.e., marriage rate, age at marriage, divorce rate, and prevalence of unmarried cohabitation) cannot be seen as indicators of an underlying concept such as the 'strength of marriage'. Multivariate ordinary least squares (OLS) regression analyses are estimated with countries as units and panel regression models are estimated in which annual time series for multiple countries are pooled. Using these models, we find that popular explanations of trends in the indicators - explanations that focus on gender roles, secularization, unemployment, and educational expansion - are also important for understanding differences among countries. We also find evidence for the role of historical continuity and societal disintegration in understanding cross-national differences.