Modeling mortality at old age with time-varying parameters

Several models of old age mortality with time-varying parameters are expressed in a single formula. In these models, the existence of an age threshold above which mortality increases over time and below which mortality decreases over time is problematic. The conditions of appearance of this threshold are expressed and shown on logistic and exponential models with empirical data. The conditions of appearance of the threshold reflect actual situations in developed countries. Richards’ curve avoids the appearance of the threshold with empirical data.     

A log-logistic regression model for a transition rate with a starting threshold

The paper presents a new type of parametric transition rate model that is particularly suitable for studying household and union formation. In such studies, it is often not easy to determine the moment at which individuals actually enter the population at risk - or at least when the risk begins to become socially important. Even in the presence of regulations stipulated by law, one might be interested in studying ‘social’ timetables. We assume that there is a constant rate for any duration and that after a certain threshold point a log-logistic rate is added, with this threshold as its time origin. This can be justified in a behavioural sense by assuming that random and social transitions arise from separate processes. We then apply the model to union formation in Italy and show how threshold and intensity effects generated by theoretical hypotheses can be revealed.     

A new method to control houseflies,Musca domestica, at waste disposal sites

Summary Investigation was carried out from 1976 to 1979 to establish a new control system against the houseflies,Musca domestica, at a sea-filling waste disposal site in Osaka Bay, Japan. Field surveys showed that the garbage was favorble for the fly breeding for 20–30 days after being disposed, while the sewage sludge and the ash from incinerated refuse were unfavorable. Comparing the fly density at the site to the reported cases of the public complaints in the urban area near to the site, a complaint threshold density of the flies at the site was estimated. Then, a control threshold density was assumed from the complaint threshold density and the reproductive rate of the housefly population. Several insecticides, as well as a surface active agent, polyoxyethylene lauryl ether (PEL), were found effective for the temporary suppression of the fly density. Based on the results obtained, the following control system was worked out. 1) Refuse is disposed onto the same area as other inorganic wastes to deteriorate the capacity of breeding sources. 2) The fly density is examined on newly disposed refuse almost everyday by landfill operators. 3) PEL is sprayed when the density slightly exceeds the control threshold density. If the density increases rather higher, insecticide should be used. 4) The disposed refuse is covered with soil or other inorganic wastes on every weekend or every other weekend by 15 cm thickness. Success in both fly control and reduction of the amounts of insecticides sprayed was achieved by a field application of this new control system.     

Population regulation by dispersal over patchy environment;

Summary A mathematical model for the population regulation is presented, which takes into account the environmental heterogeneity and the animal dispersal, and does not contain any direct density effect on reproduction or death processes. Generally speaking, there are two kinds of dispersal, one is the density independent dispersal, the other is the density dependent. It is shown that a population equilibrium can be maintained by the density dependent dispersal or threshold dispersal which occurs only when the population density exceeds a certain threshold level, but that density independent dispersal by itself can not continue to maintain a population equilibrium.     

Continuous and robust measures of the overweight epidemic: 1971–2000

This article considers alternate measures of the overweight epidemic that are more robust to measurement error, continuous in the body-mass index (BMI) at the overweight threshold, and sensitive to changes in the BMI distribution. The measures suggest that prevalence rates may understate the severity of the overweight problem. Since 1971, the prevalence of overweight has increased by 37%, while the distribution-sensitive measure has increased by 173%. Furthermore, although Hispanics have the highest prevalence of overweight, the distribution-sensitive measures reveal that overweight Hispanics exceed the overweight threshold by the smallest proportion (21%), whereas overweight non-Hispanic blacks exceed the threshold by 33%, on average.     

Life expectancy, fertility, and educational investment

In this study, we develop a model of overlapping generations where adults make decisions on consumption, fertility, and their personal education. We show that under the assumption of exogenous mortality, there are multiple steady states with club convergence occurring when mortality is sufficiently high. If mortality is sufficiently low, there will be a unique, stable steady state, and the economy will converge to a “good” steady state irrespective of where it starts from. Under the assumption of endogenous mortality with “threshold effects,” we find that club convergence will occur if the threshold is sufficiently high; conversely, a low threshold can help the economy to steer clear of the underdevelopment trap.     

The threshold hypothesis: evidence from less developed Latin American countries, 1950 to 1980

Historical research among European countries finds large differences in the level of social, economic or demographic development among countries, or regions within countries at the time marital fertility rates began their decline from traditional high levels. This research tests a threshold hypothesis which holds that fertility will decline from traditional high levels if threshold levels of life expectancy and literacy are surpassed. Using a pooled regression analysis of 1950, 1960, 1970 and 1980 crude births rates (CBRs) in 20 less developed Latin American countries, in conjunction with 10-year lagged measures of social, economic and family planning program development, analyses reveal statistically significant effects of passing Beaver's (1975) threshold levels of 1950 literacy, or 1950 life expectancy, that are independent of levels of lagged literacy (or lagged life expectancy), economic and family planning program development, as well as measures that control period effects.     

Wing dimorphism and the migratory syndrome: Correlated traits for migratory tendency in wing dimorphic insects

The hypothesis that the morphological, physiological, and behavioral traits comprising the migratory syndrome in insects are genetically correlated through pleiotropic effects of genes controlling the titre of a common hormonal determinant is explored. Evidence that juvenile hormone (JH) influences the component traits of the migratory syndrome is presented, and thus JH is assumed to be the underlying, common determinant. However, readers are cautioned that this does not imply that JH is solely responsible for these traits, nor is this necessary for the arguments presented. For wing dimorphic taxa, the “correlated traits hypothesis” predicts covariance within wing morphs between JH titre and the proportion winged. Four simple genetic models for wing-morph determination are considered: single-locus with short-winged (SW) dominant; single-locus with long-winged (LW) dominant; polygenic, fixed threshold, shifting distribution; and polygenic, shifting threshold, fixed distribution. In each case, wing morphology is assumed to be a threshold trait with the liability being JH titre at some critical stage of development. All models predict covariation between %LW and the mean JH titre of at least one of the wing morphs, but the form and direction of the relationship depends critically on the genetic model used. The results suggest that we should expect the traits associated with the migratory syndrome, and hence the trade-offs associated with the evolution of wing dimorphism, to be correlated with proportion winged and, in this sense, to be frequency-dependent.     

Measurement of poverty and equity: Some Asean social indicators experience

In ASEAN countries, improvements in measurements of poverty and equity can take several forms. First, some poverty lines should be officially adopted, e.g., a poverty threshold of $300 and a subsistence threshold of $150 (per capita per year, ‘Kravis’ dollars, mid-1970s). Second, target distributive groups should be identified and new indicators, such as a proposed index of ethnic imbalance in Malaysia, could be designed where needed. Third, quick-response well-being surveys, as in the social weather station experiment in the Philippines, could help in both the technical and the social understanding of the state of equity.     

人口年龄结构转变对我国综合要素生产率的影响——基于人力资本的视角

通过人口普查资料重新构建了年龄别人力资本存量。利用28个省份1983—2007年间的面板数据分析了年龄别人力资本对综合要素生产率的影响。发现人力资本对综合要素生产率的贡献存在着阈值效应．只有高存量的年龄别人力资本才会有促进作用。     

Inter- and intra-population variations in diapause attribute of the two-spotted spider mite,Tetranychus urticae Koch, in Japan

Summary Populations of the two-spotted spider mite,Tetranychus urticae Koch collected from various localities and from various host plants in Japan showed wide variations in diapause attribute. Diapause percentages at 18°C/9L15D varied from nearly 100% in the north to 0% in the south-west. At intermediate latitudes the mites showed wide inter-population variations. Populations on herbaceous hosts in vinyl- or glass-houses gave significantly lower incidence of diapause than those on roses and deciduous fruit trees. Presence of winter hosts and better host quality under protected environments seemed to favour non-diapausing mites. The temperature threshold for diapause expression also varied widely among local populations. Northern populations consistently had higher and less variable thresholds than populations at intermediate latitudes with thresholds between 15 and 18°C. Inbred lines derived from a population in Kyoto exhibited a wide variation in diapause percentage at 18°C. These results show that diapause inT. urticae is a quantitative threshold trait and that populations in central Japan consist of a variety of genotypes with different diapause traits. This might provide a genetic source for adaptation to local and temporal variations in environmental conditions.     

Long-Term Trends In Migratory Behavior In A Developing Country: The Case of Mexico

Comparable lifetime migration relationships are estimated for Mexico for 1950, 1960, and 1970. Moreover, migration flows from each state to every other state are separately examined for each year. A number of significant changes over time are evident in the responsiveness of Mexican internal migrants to various socioeconomic stimuli, and appreciable differences are also evident across space. Moreover, a threshold is observed such that up to about 340 miles higher origin earnings deter migration, but beyond this distance higher earnings actually encourage migration.     

人口稀释效应对经济增长异质性的影响——基于人力资本积累、R&D传导的机理分析

将人口增长“稀释效应”嵌入一个四部门水平创新框架,提出一个同时内生化个体经济行为、R&D技术进步与人力资本积累的内生增长模型,推导并刻画了经济收敛于BGP均衡及影响经济增长率的因素,为解释人口增长对经济增长产生不确定影响的“正负符号之争”提供了微观基础分析。边际贡献在于:修正设定知识积累存在非规模效应且人力资本积累存在“稀释效应”,放宽对参数的上限或正负进行先验设定。得出结论:人口增长产生负向“稀释效应”与正向“思想效应”是影响经济增长的微观传导路径,正负效应共同作用门槛值大小的不同决定人口增长与经济增长呈非单调异质性不确定影响,进一步分析了稀释效应与门槛值之间的内在关联,数值模拟量化了参数效应。     

Cross Cultural Application of the WHOQOL-SRPB in the Chinese Community with Diverse Spiritual Affiliations

In order to contribute to providing a methodology to ensure objectivity and transparency in the measurement of multidimensional poverty, this paper proposes a new threshold for the identification of the multidimensional poor which is also applicable to each of the dimensions of poverty, suitable for identifying the severely poor in developed countries. This new methodology is applied to analyse the evolution of material deprivation in Spain during the period of economic crisis, comparing the results with those obtained using other traditional approaches.     

甘肃省分县人均耕地警戒值空间差异分析

耕地警戒值是影响政府土地管理部门加强耕地保护执法力度和国民建立耕地安全意识、参与性保护耕地的重要指标。以甘肃省87个县区为基本单元,计算了人均耕地警戒值、耕地压力指数和耕地盈余/赤字量,通过空间自相关分析和空间聚类,研究了人均耕地警戒值的县际空间分异。结果表明：2009年甘肃省人均耕地警戒值区域差异明显,Moran’s I值为0.3699,呈空间显著集簇分布特征,空间格局存在＂俱乐部趋同＂现象。全省耕地管理划分为3个激励-约束级;耕地盈余量最大的县是武威市凉州区,尚有35个县用于生产食物的耕地面积为赤字。     

人口城镇化背景下的户籍制度变迁--石家庄市户籍制度改革案例分析

石家庄市的户籍制度改革坚持两个基本条件,即收入来源和住房,放开了7种人的入市条件,大大降低了农民进入大城市的门槛,解决了进城农民的户口问题,推进了城镇化速度,为我国户籍制度改革提供了值得借鉴的宝贵经验.这次改革的消极影响并没有人们想象的那么严重,出现的一些问题也将随着各项配套政策的实行得到解决.     

关于人口与自然和谐统一关系的再认识

伴随着人类经济社会的不断发展,人口、资源、环境的可持续问题日益受到人们的关注。马克思、恩格斯自然观对人与自然关系的分析及其所蕴涵的生态哲学思想．为正确认识人口与自然的和谐统一提供了独特的理论视阚。针对我国人口剧增、资源紧缺、环境恶化的严重形势,科学发展现生态文明理论的提出为实现人口与自然和谐统一提供了理论指南。     

Operationalizing De-commodification and De-familization Outcomes via the Relative Poverty Approach: An Application to Western European Countries

This article develops an approach with which to operationalise the outcomes of de-commodification and de-familisation processes. Since the de-commodification and de-familisation concepts share an emphasis on ‘a socially acceptable standard of living for individuals’ with the notion of relative poverty, the income-poverty indicator has been adopted to develop pertinent national rates. In particular, since de-commodification outcomes concern people with a socially acceptable standard of living independently of sale of their labour power, the national proportions of individuals with an equivalised disposable income above the poverty threshold who have stopped working have been accounted for. On the other hand, given that de-familisation outcomes regard individuals with a socially acceptable standard of living aside from family relationships, the national percentages of persons who actually live alone, or simulated as living alone, with an equivalised disposable income above the poverty threshold have been considered. Moreover, exploiting the equivalised disposable income computation, pertinent micro-simulations are developed to capture the role of the state and the family in de-commodification outcomes, and the contribution of the market and the state to de-familisation outcomes. On the basis of the European Union Statistics on Income and Living Conditions, an empirical application of this approach is then provided. Specifically, data for 16 European countries were used to compute the above-mentioned national rates. Furthermore, we checked whether our outcome figures exhibited any correspondence with the country-groups deriving from the classic welfare regime typologies or more in general with the measures resulting from the social policy structure.     

Behavioral processes and egg-laying decisions of the bean weevil, Callosobruchus maculatus

Empirical studies of behavioral processes were designed in a seed beetle, Callosobruchus maculatus, to distinguish between two alternative tactical models, namely, comparison tactics and threshold tactics of seed choice, and also to deduce the behavioral rule of its oviposition decisions. Search sequences and the oviposition process of the female bruchid beetle were observed and recorded. Analyzing data of the search sequence showed that the female bruchid beetle repeatedly encountered seeds randomly and tended to oviposit on a newly encountered seed in an ovposition bout. These results contradict the usual comparison models, which predict that the female will return to choose any one of the previously encountered seeds after sampling. In addition, the oviposition decision (rejection or acceptance of an encountered seed to oviposit) was analyzed with a generalized linear modeling (GLIM) technique. Modeling showed that the probability of accepting a seed with different numbers of eggs on it changed during her egg-laying process. This evidence supports the idea that the female is using a threshold tactic and that her acceptance threshold is being adjusted by experience gained during the egg-laying process. The analysis of statistical modeling also showed that both the time since the last oviposition and the number of eggs which had been laid by the female had a significant effect on the probability of accepting seeds with different numbers of eggs. Therefore, a time measuring system and the physiological state variable, e.g., eggload of the female, should be included in the behavioral rule to explore how the female makes her decision in the egg-laying process and to examine the importance of choice behavior as a component of selection and adaptation. Received: May 8, 1998 / Accepted: September 20, 1999     

Divergence in Age Patterns of Mortality Change Drives International Divergence in Lifespan Inequality

In the past six decades, lifespan inequality has varied greatly within and among countries even while life expectancy has continued to increase. How and why does mortality change generate this diversity? We derive a precise link between changes in age-specific mortality and lifespan inequality, measured as the variance of age at death. Key to this relationship is a young–old threshold age, below and above which mortality decline respectively decreases and increases lifespan inequality. First, we show for Sweden that shifts in the threshold’s location have modified the correlation between changes in life expectancy and lifespan inequality over the last two centuries. Second, we analyze the post–World War II (WWII) trajectories of lifespan inequality in a set of developed countries—Japan, Canada, and the United States—where thresholds centered on retirement age. Our method reveals how divergence in the age pattern of mortality change drives international divergence in lifespan inequality. Most strikingly, early in the 1980s, mortality increases in young U.S. males led to a continuation of high lifespan inequality in the United States; in Canada, however, the decline of inequality continued. In general, our wider international comparisons show that mortality change varied most at young working ages after WWII, particularly for males. We conclude that if mortality continues to stagnate at young ages yet declines steadily at old ages, increases in lifespan inequality will become a common feature of future demographic change.