University of Rochester

About: University of Rochester is a education organization based out in Rochester, New York, United States. It is known for research contribution in the topics: Population & Laser. The organization has 63915 authors who have published 112762 publications receiving 5484122 citations. The organization is also known as: Rochester University.

Intellectual Impairment in Children with Blood Lead Concentrations below 10 μg per Deciliter

Abstract: background Despite dramatic declines in children’s blood lead concentrations and a lowering of the Centers for Disease Control and Prevention’s level of concern to 10 µg per deciliter (0.483 µmol per liter), little is known about children’s neurobehavioral functioning at lead concentrations below this level. methods We measured blood lead concentrations in 172 children at 6, 12, 18, 24, 36, 48, and 60 months of age and administered the Stanford–Binet Intelligence Scale at the ages of 3 and 5 years. The relation between IQ and blood lead concentration was estimated with the use of linear and nonlinear mixed models, with adjustment for maternal IQ, quality of the home environment, and other potential confounders. results The blood lead concentration was inversely and significantly associated with IQ. In the linear model, each increase of 10 µg per deciliter in the lifetime average blood lead concentration was associated with a 4.6-point decrease in IQ (P=0.004), whereas for the subsample of 101 children whose maximal lead concentrations remained below 10 µg per deciliter, the change in IQ associated with a given change in lead concentration was greater. When estimated in a nonlinear model with the full sample, IQ declined by 7.4 points as lifetime average blood lead concentrations increased from 1 to 10 µg per deciliter. conclusions Blood lead concentrations, even those below 10 µg per deciliter, are inversely associated with children’s IQ scores at three and five years of age, and associated declines in IQ are greater at these concentrations than at higher concentrations. These findings suggest that more U.S. children may be adversely affected by environmental lead than previously estimated.

Safety and Immunogenicity of Two RNA-Based Covid-19 Vaccine Candidates.

Abstract: Background Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and the resulting disease, coronavirus disease 2019 (Covid-19), have spread to millions of persons worldw...

The Interaction of Selection and Linkage. I. General Considerations; Heterotic Models.

Abstract: HILE the theory of the genetic changes in a population due to selection is quite well understood for single loci, our theory for multiple-gene characters is in a rudimentary stage. Most of the formulations for multiple-gene characters are simply extensions of single-locus models, extensions which ignore the problem of linkage. There are, however, a few papers in which the role of linkage has been investigated for more or less special cases of selection (KIMURA 1956; LEWONTIN and KOJIMA 1960; BODMER and PARSONS 1962). The results of these investigations were sufficient to show that even for relatively simple cases (two loci, simple symmetrical selective values) linkage might have profound effects on the course of natural selection and, pari passu, natural selection may have major effects on the distribution of coupling and repulsion linkage in a population. The results of the investigations of LEWONTIN and KOJIMA (1960) of the twolocus model can be summarized as follows: (1) If the fitnesses are additive between loci (no epistasis), linkage does not effect the final equilibrium state of the population. (2) If linkage is tighter than the value demanded by the magnitude of the epistasis (the greater the epistasis the greater the value) there may be permanent linkage disequilibrium and alteration of equilibrium gene frequencies. (3) The rate of genetic change with time is affected by the tightness of the linkage. (4) In some cases stable gene frequency equilibria are possible only if linkage is tight enough. Although these conclusions were based only on two-locus model and for selective values of a fairly restricted sort, they point clearly to the importance of taking linkage into account in understanding the changes of gene frequencies in populations. In fact, some experimental results (an example of which will be given below) can be understood only if the interaction of selection and linkage is taken into account, The equations describing the interaction between selection and linkage (see below) do not usually have general literal solutions. It is for this reason that the authors cited above have restricted themselves to relatively simple cases. In view of the interesting findings of those previous papers, however, it is worthwhile to explore the subject more intensively. To do so requires the numerical rather than general literal solutions to the equations, but such numerical solutions apply, obviously, only to the particular parameter values chosen. To make such a nu-

Does Schooling Cause Growth

Abstract: A number of economists find that growth and schooling are highly correlated across countries. A model is examined in which the ability to build on the human capital of one's elders plays an important role in linking growth to schooling. The model is calibrated to quantify the strength of the effect of schooling on growth by using evidence from the labor literature on Mincerian returns to education. The upshot is that the impact of schooling on growth explains less than one-third of the empirical cross-country relationship. The ability of reverse causality to explain this empirical relationship is also investigated.