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Demographic Effects (demographic + effects)
Selected AbstractsCOMMENT: THE DECLINE OF JAPAN'S SAVING RATE AND DEMOGRAPHIC EFFECTSTHE JAPANESE ECONOMIC REVIEW, Issue 2 2006ETSURO SHIOJI No abstract is available for this article. [source] Identifying Welfare Effects from Subjective QuestionsECONOMICA, Issue 271 2001Martin Ravallion We argue that the welfare inferences drawn from answers to subjective,qualitative survey questions are clouded by concerns over the structure of measurement errors and how latent psychological factors influence observed respondent characteristics. We propose a panel data model that allows more robust tests and we estimate the model on a high-quality survey for Russia. We find significant income effects on an individual's subjective economic welfare. Demographic effects are weak at given income per capita. Ill-health and becoming unemployed lower welfare at given current income, although the unemployment effect is not robust, and returning to work does not restore welfare without an income gain. [source] Age,period,cohort modelling of alcohol volume and heavy drinking days in the US National Alcohol Surveys: divergence in younger and older adult trendsADDICTION, Issue 1 2009William C. Kerr ABSTRACT Aims The decomposition of trends in alcohol volume and heavy drinking days into age, period, cohort and demographic effects offers an important perspective on the dynamics of change in alcohol use patterns in the United States. Design The present study utilizes data from six National Alcohol Surveys conducted over the 26-year period between 1979 and 2005. Setting United States. Measurements Alcohol volume and the number of days when five or more and eight or more drinks were consumed were derived from overall and beverage-specific graduated frequency questions. Results Trend analyses show that while mean values of drinking measures have continued to decline for those aged 26 and older, there has been a substantial increase in both alcohol volume and 5+ days among those aged 18,25 years. Age,period,cohort models indicate a potential positive cohort effect among those born after 1975. However, an alternative interpretation of an age,cohort interaction where drinking falls off more steeply in the late 20s than was the case in the oldest surveys cannot be ruled out. For women only, the 1956,60 birth cohort appears to drink more heavily than those born just before or after. Models also indicate the importance of income, ethnicity, education and marital status in determining these alcohol measures. Conclusions Increased heavy drinking among young adults in recent surveys presents a significant challenge for alcohol policy and may indicate a sustained increase in future US alcohol consumption. [source] Causes and consequences of adaptive seasonal sex ratio variation in house sparrowsJOURNAL OF ANIMAL ECOLOGY, Issue 5 2006ARILD HUSBY Summary 1Here we examine how sex ratio variation in house sparrow broods interacts with other demographic traits and parental characteristics to improve the understanding of adaptive significance and demographic effects on variation in sex ratio. 2The sex ratio in complete broods did not deviate significantly from parity (54·9% males). 3There was sex-specific seasonal variation in the probability of recruitment. Male nestlings that hatched late in the breeding season had larger probability of surviving than early hatched males. 4An adaptive adjustment of sex ratio should favour production of an excess of males late in the breeding season. Accordingly, the proportion of male offspring increased throughout the breeding season. 5A significant nonlinear relationship was present between sex ratio and age of the female. However, there was no relationship between parental phenotype and standardized hatch day that could explain the observed seasonal change in sex ratio. 6The sex-specific number of offspring recruited by a pair to subsequent generations was closely related to the brood sex ratio. 7These results indicate an adaptive adjustment of sex ratio to seasonal variation in environmental conditions that affects the offspring fitness of the two sexes differently. Our results also suggest that such a sex ratio variation can strongly influence the demography and structural composition of small passerine populations. [source] Approaches for testing herbivore effects on plant population dynamicsJOURNAL OF APPLIED ECOLOGY, Issue 5 2006STACEY L. HALPERN Summary 1As plant invasions pose one of the greatest threats to biodiversity, it is critical to improve both our understanding of invasiveness and strategies for control. Much research into plant invasions and their management, including biological control, assumes strong demographic effects by natural enemies, including herbivores. However, the importance of natural enemies in the regulation of plant populations remains controversial: some ecologists contend that they rarely affect plant populations, and others that they can strongly limit plant population sizes. 2We briefly review the conflicting views and suggest that new approaches to gather and analyse data are needed before the effects of natural enemies on plant populations can be fully characterized. 3We outline experimental and analytical approaches that incorporate density dependence into population models and thus provide a more complete test of the long-term effects of natural enemies on plant populations. We also introduce new methods for obtaining stochastic estimates of equilibrium density, which will provide a key test of enemy effects on plant population size. 4Synthesis and applications. Designing effective strategies for invasive plant management requires information about the factors that limit plant population size. Together, the experiments and analyses we describe measure more clearly how natural enemies influence plant population dynamics. They will provide an important tool in evaluating the role of enemy release in plant invasions and for predicting the potential success of biological control. Such information should help to prioritize strategies that are most likely to control invasive plants effectively and will contribute to risk assessment when considering the release of non-native natural enemies as biological control agents. [source] Household meat demand in Greece: A demand systems approach using microdataAGRIBUSINESS : AN INTERNATIONAL JOURNAL, Issue 1 2003Panagiotis Lazaridis This article examines meat consumption patterns of households in Greece using data from family budget surveys. For that purpose the linear approximate Almost Ideal Demond System was employed to investigate the economics and demographic effects on the demand for four types of meat. Prices were adjusted for quality, and the demographic translation method was used to incorporate the demographic variables. Finally, the two-stage generalized Heckman procedure was employed to take into account censoring of the dependent variables. [EconLit citations: Q11, D12.] © 2003 Wiley Periodicals, Inc. Agribusiness 19: 43,59, 2003. [source] Interspecific seed discounting and the fertility cost of hybridization in an endangered speciesNEW PHYTOLOGIST, Issue 1 2008Kevin S. Burgess Summary ,,Hybrid fertilizations can have negative demographic effects on taxa by usurping ovules that would otherwise give rise to nonhybrid offspring. The consequent reduction in conspecific matings may be exaggerated in rare taxa and constitutes a fertility cost that has rarely been quantified. ,,Here, the effect of interspecific mating was estimated on the fecundity of locally rare red mulberry (Morus rubra), which hybridizes with introduced white mulberry (Morus alba) and red ¥ white hybrids. First, the asymmetry in pollen production among red, white and hybrid mulberry in two sympatric populations was quantified. The fertility cost of hybridization was then assessed experimentally by estimating seed production and rates of interspecific mating in red mulberry trees from plots where white and hybrid mulberry trees were selectively removed. ,,On average, the percentage of mulberry pollen per plot produced by red mulberry (8%) was significantly lower than the mean for white and hybrid mulberry combined (92%). Experimentally removing white and hybrid mulberry increased the siring fertility of red mulberry by 14% but produced no change in seed set. ,,Results indicate that seeds of red mulberry, ordinarily sired by conspecific pollen, are being discounted through fertilization of ovules by heterospecific pollen, which may contribute to local decline of red mulberry. [source] Biological condition of adult migrants and nonmigrants in Wroc,aw, PolandAMERICAN JOURNAL OF HUMAN BIOLOGY, Issue 2 2008Alicja Szklarska Human migration and its economic, social, and demographic effects can lead to health consequences for individuals and populations. In the present study, we estimated differences in health status between migrant (those who had come to Wroc,aw at the age of ,16 years) and nonmigrant (those who had lived in Wroc,aw since birth or had come with their parents) inhabitants of Wroc,aw, Poland. Three hundred and sixty seven males and 496 females aged 40 and 50 underwent medical examination, and were asked to fill out a questionnaire comprising social, demographic, and life style information. Health status was assessed by blood pressure, heart rate, fasting lipid profile, glucose, height, and measures of fatness (BMI, WHR, sum of skinfolds). Comparisons were made based on Borkan's and Norris's profiles. Student's t -test showed significant differences in diastolic blood pressure, heart rate, total cholesterol, and glucose levels between two groups of males, in favor of migrants. Male migrants were also significantly taller than their peers born in Wroc,aw. In females, migrants had significantly lower blood pressure and heart rate than nonmigrants. In interpreting the results two possible, not mutually exclusive, mechanisms are proposed: selective spatial mobility, and changes toward healthier life style as an adaptation to new urban environment. Am. J. Hum. Biol., 2008. © 2007 Wiley-Liss, Inc. [source] Movement and survival parameters of translocated and resident swift foxes Vulpes veloxANIMAL CONSERVATION, Issue 3 2003Axel Moehrenschlager Conservation programmes increasingly involve the translocation of animals to reinforce failing populations or establish new ones. To help guide translocation programmes of swift foxes (Vulpes velox) or other imperilled species, we aimed to discern factors affecting translocation success among reintroduced swift foxes in Canada. Post-release movements characterized three stages. In the initial acclimation phase, foxes moved erratically and quickly distanced themselves from release sites. During the establishment phase, distances from the release site did not change significantly but daily movements were more wide-ranging than those of concurrently tracked, resident swift foxes. In the final settlement phase, movements of translocated foxes reflected those of resident individuals. Radio-telemetry showed that survival and reproductive success were highest for swift foxes with small dispersal distances, suggesting that measures should be taken to acclimatize animals to release sites. Since females had lower survival rates than males, translocations should also use a greater proportion of females to establish balanced sex ratios in the population. Translocated juveniles dispersed less far but survived and reproduced as well as translocated adults, suggesting that juveniles can be used to establish translocated foxes in small, protected areas, while minimizing demographic effects on source populations. The fact that survival rates and litter sizes of translocated foxes were similar to those of resident animals indicates that translocation can be an effective reintroduction tool for this endangered species, and possibly other foxes. [source] | |||||||||||||