Socio-economic and health determinants of transitions to adult dependency in South Korea, 2008-2014.

OBJECTIVES: The aim of this study is to identify the determinants of transitions to and possibly back from dependence. STUDY DESIGN: The Korean Longitudinal Study of Aging, 2006-2014. METHODS: The transitions between non-dependence and difficulties in activities of daily living -instrumental (IADL) or not (ADL)-are distinguished between stability, deterioration, death, or recovery in multilevel logistic regressions. RESULTS: Controlling for other covariates, women are more likely to remain without difficulty than men, dependants are more likely out of the labor force or unemployed, city dwellers are more likely dependent. Subjective health helps predict health two years later, as grip power, score of cognition, depression, cardiac and cerebrovascular diseases, and the number of difficulties in IADL (but not in ADL). Dependants with difficulties in IADL reporting no caregiver survive longer but are less likely to recover. Difficulties in ADL overwhelm any other available determinant. The Gompertz-like increase in the death rate with age no longer holds true for ADL dependants. Cardiac and cerebrovascular pathologies and smoking and drinking favor the transition to disability. CONCLUSIONS: Socio-economic and medical factors identify a multifactorial determination of the risk to dependence and changes in dependence status, controlling for each effect and selection bias.

Protected polymorphism in the two-locus haploid model with unpredictable fitnesses.

In an unpredictable environment, the distributions of alleles from which polymorphism can be maintained forever belong to a certain set, the C-viability kernel. Such a set is calculated in the two-locus haploid model, as well as the corresponding fitnesses at any time which make this maintenance possible. The dependence of the C-viability kernel on the set U of admissible fitnesses and on the recombination rate r is studied. Notably, the C-viability kernel varies rapidly in the neighborhood of equal fitness of AB and ab; it becomes empty when ab has a fitness below a certain function, which is delineated, of the recombination rate. The properties of the two-locus model under constraints, out of equilibrium and with unpredictable selection are thus presented.

Population paths implied by the mean number of pairwise nucleotide differences among mitochondrial DNA sequences.

Scenarios, such as populations experiencing a bottleneck or an exponential growth, have been suggested as candidates for explaining the observed differences among mitochondrial DNA sequences in a sample of a given population closed to migrations. Here, population size is considered as capable of varying, and the set of the at least 95% most probable population paths capable of producing the observed mean number of pairwise nucleotide differences is delineated. To do this, the mean and the variance of coalescence times of two genes taken in an n-genes sample with varying population size are expressed. The observed mean coalescence time already echoed a set of population paths due to the variance associated to the coalescent process, but only specific scenarios have been studied, such as the bottleneck or the exponential function. However, mitochondrial DNA data does not reflect a single scenario, after the effect of the variance. These scenarios implied by pairwise nucleotide differences are described through a set-valued function, the 'regulation map', a convenient way to represent temporal population paths.

Variable age at onset in insulin-dependent diabetes mellitus, by the marker-association-segregation-chi 2 method.

The marker-association-segregation-chi 2 (MASC) method with consideration of age, for nonaffected persons, and of age at onset, for affected persons, was applied to a sample of 308 HLA-typed families. Hazard rates modeling the instantaneous risk of catching the disease were estimated under the exponential distribution and with satisfactory goodness of fit. This class of models shows that the hypothesis of the absence of parental imprinting cannot be rejected for insulin-dependent diabetes mellitus.

Capital accumulation, inertia of consumption and norms of reproduction.

"A model of capital accumulation is built in relation with fertility and consumption. Avoiding [the imposition of] a direct analytical relationship between these three variables, the author studies the set of possible evolutions under the constraints imposed by the inertia of habit change. The conflict between the necessity to avoid impoverishment, the desire to increase consumption when possible and the reproduction intensity delineate the set of viable solutions and the set of attitudes leading to capital extinction. This qualitative view of change of behaviors provides an alternative explanation to historical fertility fluctuations outside the usual Easterlin framework." The geographical focus is on Western developed countries, with particular reference to Sweden.

Malthus, Boserup and population viability.

The Malthus-Boserup explanatory framework is revisited from the point of view of viability theory. Instead of imposing a univocal relationship between population pressure and level of knowledge, the way technology will change is not determined, it is only constrained. This leads to regard any situation as associated to a set of reachable futures. When no possibility is left for systems to avoid extinction, systems are no longer viable. Hence, the control-phase space can be divided into regions corresponding to gradual danger or security. This point of view allows the introduction of ideas such as incentives to create or to use new knowledge, gives a role to the threatening power of Malthusian checks, and leaves space for a specific variety of behaviors. The Boserupian theme then appears indirectly, emerging from the constraints imposed by the inertia of technological change.

How reporting delay, duration of follow-up and number of cases affect the estimates of the incubation time of transfusion-associated AIDS cases.

The authors discuss the impact of reporting delay, duration of follow-up, and number of cases in a sample on estimates of the incubation time of transfusion-associated AIDS cases. "This article comes to the conclusion that the accuracy of the incubation time estimate would depend on the sample size rather than on the duration of follow-up." (SUMMARY IN FRE)

[Time series in historical demography]. / Temporalites en demographie historique.

PIP: The author examines the use of time series data in historical research, particularly in historical demography. He explains how mathematical techniques can be used to study the dynamics of historical populations. He also uses demographic data from England and France to show how the relationships among demographic, economic, and climatic events have influenced the course of political events. Specific attention is given to factors affecting fertility in seventeenth-century France. (SUMMARY IN ENG)^ieng

Turbulent dynamics in a XVIIth century population.

"A reconstruction of the population of the Pays de Caux [France] (1589-1700) yields the time series of a fertility behavior indicator....An attempt is made to explain this general temporal structure by using a simulation model based on the autoregulation model (the so-called European Marriage Pattern), putting into play a choice of the spouse function, a fertility function, modalities of marriage and remarriage, under the environmental forcing of the reconstructed mortality conditions. The correspondence between reconstruction and simulation turns out to be quite good....A second simulation with simulated mortality conditions shows a bifurcation point: as the mean frequency of crisis increases, the state of the system leaves the lower level and concentrates more and more in the higher level." (SUMMARY IN FRE)

Predicting the "vagaries" of mortality: the causes of death in Bamako from 1974 to 1985.

"The overall downward trend in African mortality is interrupted by recurring epidemics. This article investigates the nature of those temporary fluctuations, using cause-of-death data drawn from deaths registered in Bamako [Mali] over an 11-year period. The use of time-series analysis produces findings that can be used in three ways: first, to provide a short-term forecasting tool for public health officials; secondly, to clarify the relationship between the cause of death and exogenous mortality factors, particularly climatic and economic; thirdly, to assist in the analysis of synergies between disease and malnutrition, and intra-household transmission as an aggravating factor contributing to the seriousness of a disease."

Increased risk of measles mortality for children with siblings among the Fula Bande, Senegal.

In a survey of the Fula Bande, a rural population of Senegal, deaths and causes of death have been registered during an 8-year period. Measles is responsible for 31% of deaths of children 6 months to 9 years old. Under the mortality conditions of the period studied, a 6-month-old child has a 15% chance of dying from measles at some point. Children with siblings have a higher mortality risk during measles epidemics than children without siblings. Since the risk of infection seems equal in these two groups, the difference is probably due to more severe infection among multiple cases with close contact. In one epidemic where measles cases were registered, case-fatality rates were indeed higher in compounds with several measles cases.