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O Stark

Publications and source records attributed to O Stark.

At least 37 records · Page 2Linked to original sources
PubMed1986

Inducing fertility change: a game-theoretic approach.

This paper explores the inducement of fertility change in situations where actual fertility levels do not coincide with socially optimal fertility levels. The motivating example is that of higher than socially optimal levels of fertility in less developed countries (LDCs), but the approach is equally applicable to contexts of lower than socially optimal levels of fertility in developed countries. The paper proposes a prisoner's dilemma characterization of higher than socially optimal levels of fertility in LDCs and offers a resolution of the dilemma, and hence a possible route to fertility-reduction policies, through the generation of mutual altruism. The prisoner's dilemma characterization hinges on the assumption that there is some social sharing of the costs associated with a given level of fertility but less or none with respect to the benefits. The mutual altruism solution depends on representing an agent's preferences as a specific convex combination of his/her and the other agent's original utilities. The unique critical level of such altruism is identified and hence a stopping rule is provided. Several examples from the array of extensions and possible implications of this approach are discussed briefly.

Behavior↗
PubMed1986

Labor migration and risk aversion in less developed countries.

"In this paper we question the pioneering work of Todaro, which states that rural-to-urban labor migration in less developed countries (LDCs) is an individual response to a higher urban expected income. We demonstrate that rural-to-urban labor migration is perfectly rational even if urban expected income is lower than rural income. We achieve this under a set of fairly stringent conditions: an individual decision-making entity, a one-period planning horizon, and global risk aversion. We obtain the result that a small chance of reaping a high reward is sufficient to trigger rural-to-urban labor migration."

Behavior↗
PubMed1986

Antibody response to sheep red blood cells in four substrains of BB rats, some other strains and interstrain F2 hybrids.

Primary and secondary antibody responses to SRBC were assayed in three substrains of dp BB rats, one strain of ndp BB rats, in their parental WOK rats, in highly inbred LEW rats, in two RT1 congenic strains LEW.1A and LEW.1W, and in the recombinant LEW.1WR2 strain. Furthermore, interstrain F1 and F2 hybrids of two dp BB substrains with congenic animals were tested. A significant lowering of the primary antibody response was found in two dp BB substrains and in the recombinant LEW.1WR2 strain. A transient lowering was shown in ndp BB rats. The third dp BB substrain responded well. The observed differences among three dp BB substrains only indicate that the level of antibody response to SRBC cannot be taken as a further marker, besides the RT1uv haplotype, for spontaneous development of the IDDM in BB rats. The observed decrease in the primary antibody response in the RT1 recombinant LEW.1WR2 rats and in one group of interstrain F2 hybrids typing as homozygous RT1uv may have another meaning. They could indicate some immunoregulatory effects of the RT1 haplotype on the supposedly multigenic response to SRBC in rats. No significant differences were found in the secondary antibody responses to SRBC.

Animals↗
PubMed1986

Obesity in 16-year-olds assessed by relative weight and doctors' rating.

Weights and heights at age 16 of 5652 boys and 5280 girls from the National Child Development Study (NCDS) were measured. At this examination, school medical officers rated the boys and girls into one of the following categories: grossly obese, moderately obese, normal, thin or very thin. A comparison is made between doctors' rating and assessment of obesity by relative weight (RW). Obesity was defined as RW greater than 120. Overall 803 (15.2 per cent) girls were rated obese by doctors compared with 469 (8.9 per cent) identified by RW. Only 414 (7.8 per cent) girls were considered obese by both methods. In boys the difference between the two methods was less marked. There were 362 (6.4 per cent) boys rated as obese by doctors, 404 (7.2 per cent) by relative weight and 262 (4.6 per cent) by both methods. The discrepancies demonstrate that one method of assessment cannot replace another. Doctors' rated considerably more girls than boys as obese. Although at this age girls were heavier than boys for a given height, the doctors' rating may also reflect the different attitudes towards obesity in men and women which are prevalent in our society. Without comparison with a more accurate measure of adiposity it is not possible to reach a definite conclusion as to whether clinical assessment, relative weight, or indeed both methods combined are the most suitable for identifying obese adolescents.

Adolescent↗
PubMed1985

Occurrence of antibodies against gene products of the major histocompatibility complex in normal sera of diabetes-prone BB rats.

Natural antibodies were detected in normal sera of diabetes-prone rats of substrain dp BB/DK (19.5%), non-diabetes-prone ndp BB/PhiK (17.8%) and their ancestral randombred strain WOK (2.2-7.5%). These antibodies were haemagglutinins specifically reacting with antigenic products of the RT1.A region, mainly with products of RT1.Aa,d,f haplotypes. The possible causes of this unusual finding are discussed.

Animals↗
PubMed1984

Animal model of the insulin-dependent Diabetes mellitus in BB rats: their RT1u homogeneity and prolonged survival of allogeneic skin grafts.

Two substrains of BB rats spontaneously developing the insulin-dependent diabetes-like syndrome were studied. Both the partially inbred BB/K and randombred BB/DK substrains proved RT1u homozygous. Their ancestral WOK stock was shown to be heterogeneous for the RT1u (f = 0.84) and RT1a (f = 0.16) haplotypes. Regarding the H-loci of the RT1 complex, the RT1 haplotype of BB rats seems not to be a recombinant between RT1u and RT1a from the ancestral WOK stock. The generally lowered immune responsiveness of BB recipients to allogeneic skin grafts might be caused by a mutation event at their RT1u haplotype or by some other "major gene(s)" from their genetic background.

Animals↗
PubMed1984

Results of the local graft-versus-host reaction support the immunogenetic concept of the insulin-dependent Diabetes mellitus in BB rats.

The local GVHR was studied by the popliteal lymph node assay in adult randombred BB/DK rats, their parental WOK rats and their interstrain F1 and BC1 hybrids as well as in the LEW triplet of congenic and recombinant strains. A strong GVHR was observed when BB/DK rats were used as recipients. On the contrary, only weak GVHR were found in most cases with BB/DK donors of lymphoid cells. This lowered graft-versus-host reactivity of BB lymphoid cells provided further evidence for a genetically determined defect of the differentiation process of lymphoid cell subpopulations, most probably caused by the mutant RT1u haplotype in BB rats.

Animals↗
PubMed1984

Incidence of the insulin-dependent Diabetes mellitus in BB rats: their genetic heterogeneity and susceptibility to infection.

Incidence and onset of the IDDM were studied in progeny of different mating types and generations of the partially inbred BB/K and randombred BB/DK substrains. The first two generations of BB/K rats showed a high incidence (75-80%) of IDDM which corresponded to their relative genetic homogeneity (homozygotes for haemoglobin and esterase-1 loci). But the incidence of IDDM did not depend on the type of parental mating, probably due to residual genetic heterogeneity (for two non-RT1 antigens and three biochemical traits). The randombred BB/DK strain showed a relatively low incidence (11.4-16.7%) of IDDM, and its later onset. Mycoplasma infection lowered drastically the IDDM incidence in the 3rd generation of BB/K rats. This infection caused most probably a pronounced distortion of the segregation ratio in the (BB/K x LEW)F2 hybrids. The RT1u haplotype showed a lethal or sublethal effect in the homozygous state. The BB/K substrain became extinct in the 7th generation from mycoplasma infection. Interactions between infection and development of IDDM, its polygenic nature and role of the RT1u variant haplotype are discussed.

Animals↗
PubMed1983

Prevalence of obesity in British children born in 1946 and 1958.

The prevalence of overweight at ages 7 and 11 years and in late adolescence was compared in two nationally representative cohorts of British children born in 1946 and 1958. Overweight was defined as weight that exceeded the standard weight for height, age, and sex by more than 20% (relative weight greater than 120%). The prevalence of overweight among 7 year olds born in 1958 was nearly twice that among those born in 1946. Changes in infant feeding practices, food supply, and level of physical activity might be responsible for this difference. By adolescence the prevalence of obesity in both cohorts had increased but the difference between cohorts had almost disappeared. Around 9% of adolescent girls and 7% of adolescent boys were overweight. If infant feeding practices have an influence on prevalence of overweight at 7 years the data from the two cohorts suggest that such an effect does not persist. In neither cohort was there a significant relation between the prevalence of obesity and social class in boys, but in girls the prevalence was higher among those from the lower socioeconomic groups. Correlation coefficients showing the strength of the relation between relative weights at different ages were remarkably similar for both cohorts. The risk of being obese later in childhood for those who had not been obese at the age of 7 was less than one in 10, whereas for those with a relative weight greater than 130% the risk exceeded six in 10.

Adolescent↗
PubMed1983

Major histocompatibility complex (MHC)-independent differences between diabetes-prone BB rats and their parental Wistar rat strain in some hematologic and metabolic traits.

In connection with the fact that BB rats are homogeneous for haplotype RT1u and their parental Wistar rat stock is heterogenous for haplotypes RT1u and RT1a the influence of the RT1 haplotypes on some hematologic and metabolic traits was studied. The findings indicate marked differences between BB rats and their parental strain independent of haplotype RT1 so that the changed genetic background of the BB rat rather than the haplotype per se seems to be the reason for the differences observed.

Animals↗