Towards an in situ, full-power gauge of the focal-volume intensity of petawatt-class lasers.

About 50 years ago, Sarachick and Schappert [Phys. Rev. D. 1, 2738-2752 (1970)] showed that relativistic Thomson scattering leads to wavelength shifts that are proportional to the laser intensity. About 28 years later, Chen et al. [Nature 396, 653-655 (1998)] used these shifts to estimate their laser intensity near 1018 W/cm 2. More recently, there have been several theoretical studies aimed at exploiting nonlinear Thomson scattering as a tool for direct measurement of intensities well into the relativistic regime. We present the first quantitative study of this approach for intensities between 1018 and 1019 W/cm 2. We show that the spectral shifts are in reasonable agreement with estimates of the peak intensity extracted from images of the focal area obtained at reduced power. Finally, we discuss the viability of the approach, its range of usefulness and how it might be extended to gauge intensities well in excess of 1019 W/cm 2.

Effects of the consumption of rice from non-KBD areas and selenium supplementation on the prevention and treatment of paediatric Kaschin-Beck disease: an epidemiological intervention trial in the Qinghai Province.

OBJECTIVE: Based on the aetiological hypothesis of Kaschin-Beck disease (KBD), different interventions were adopted, and the preventive and therapeutic effects of interventions was observed and evaluated in this trial. DESIGN: A total of 358 children from seven villages of Qinghai Province in China were examined, and 280 children aged 6-11 years old were eligible for the trial. The children were divided into three groups that received either no intervention (n = 64), 150 kg/person of rice from non-KBD areas (n = 103) or 7 kg/family of selenium-iodine salt (n = 113) for 12 months. Data were collected and used to calculate the proportion of patients with X-ray lesions, the proportion of new patients and the metaphyseal repair rate. All indicators were analysed with Pearson chi-square or Fisher's exact tests. The registration number of this trial is ChiCTR-PNRC-12002309 (http://www.chictr.org). RESULTS: After interventions, the proportion of patients with X-ray lesions increased dramatically in the control group and decreased significantly in two intervention groups; significant differences were seen between the control group and two intervention groups (P < 0.05). Moreover, significant differences were observed in the proportions of new patients and the metaphyseal repair rates between the control group and two intervention groups (P < 0.05). Additionally, the proportion of new patients was lowest and the metaphyseal repair rate was highest in group B. CONCLUSIONS: The effects of eating rice from non-KBD areas and selenium supplementation on the prevention and treatment of paediatric KBD were notable, the consumption of rice might be the most effective and safest intervention and should be encouraged.

Bayesian modeling of age-specific survival in nesting studies under Dirichlet priors.

There has been much work done in nest survival analysis using the maximum likelihood (ML) method. The ML method suffers from the instability of numerical calculations when models having a large number of unknown parameters are used. A Bayesian approach of model fitting is developed to estimate age-specific survival rates for nesting studies using a large class of prior distributions. The computation is done by Gibbs sampling. Some latent variables are introduced to simplify the full conditional distributions. The method is illustrated using both a real and a simulated data set. Results indicate that Bayesian analysis provides stable and accurate estimates of nest survival rates.

Cell contact-dependent activation of alpha3beta1 integrin modulates endothelial cell responses to thrombospondin-1.

Thrombospondin-1 (TSP1) can inhibit angiogenesis by interacting with endothelial cell CD36 or proteoglycan receptors. We have now identified alpha3beta1 integrin as an additional receptor for TSP1 that modulates angiogenesis and the in vitro behavior of endothelial cells. Recognition of TSP1 and an alpha3beta1 integrin-binding peptide from TSP1 by normal endothelial cells is induced after loss of cell-cell contact or ligation of CD98. Although confluent endothelial cells do not spread on a TSP1 substrate, alpha3beta1 integrin mediates efficient spreading on TSP1 substrates of endothelial cells deprived of cell-cell contact or vascular endothelial cadherin signaling. Activation of this integrin is independent of proliferation, but ligation of the alpha3beta1 integrin modulates endothelial cell proliferation. In solution, both intact TSP1 and the alpha3beta1 integrin-binding peptide from TSP1 inhibit proliferation of sparse endothelial cell cultures independent of their CD36 expression. However, TSP1 or the same peptide immobilized on the substratum promotes their proliferation. The TSP1 peptide, when added in solution, specifically inhibits endothelial cell migration and inhibits angiogenesis in the chick chorioallantoic membrane, whereas a fragment of TSP1 containing this sequence stimulates angiogenesis. Therefore, recognition of immobilized TSP1 by alpha3beta1 integrin may stimulate endothelial cell proliferation and angiogenesis. Peptides that inhibit this interaction are a novel class of angiogenesis inhibitors.

The chicken GATA-6 locus contains multiple control regions that confer distinct patterns of heart region-specific expression in transgenic mouse embryos.

The GATA-6 transcription factor is expressed in cardiogenic cells and during subsequent stages of heart development in diverse vertebrate species. To gain insights into the molecular events that govern this heart-restricted expression, we isolated the chicken GATA-6 gene and used several approaches to screen for associated control regions. Our analysis of two chicken GATA-6/lacZ constructs in transgenic mouse embryos was particularly revealing. One GATA-6/lacZ construct, which has 1.5 kilobase pairs of upstream sequences along with the promoter and first intron, was expressed exclusively in the atrioventricular canal region of the heart. This expression pattern is novel and appears to mark specialized myocardial cells that induce underlying endocardial cells to initiate valve formation. The other GATA-6/lacZ construct, which has an additional 7.7 kilobase pairs of upstream sequences, was expressed in the ventricle and outflow tract in addition to the atrioventricular canal. The failure of these GATA-6 control regions to function as enhancers in transfected cardiac myocyte cultures underscores the importance of using transgenic approaches to elucidate transcriptional controls that function in the developing heart. Although the endogenous GATA-6 gene is expressed throughout the heart, our results indicate that this is effected in a heart region-specific manner.

[Study on genetic polymorphism of isozyme in natural populations of Drosophila virilis].

Using techniques of polyacrylamide slab electrophoresis and agarose electrophoresis, we have detected genetic variation at 6 loci which coding for enzymes in 4 local samples from natural population of Drosophila virilis. We found 50% of the loci detected are polymorphic, depending on the criterion of polymorphism used. An individual is heterozygotes on the average at 27.13% of its loci. The amount of genetic variation fluctuates widely from locus to locus. At Est-alpha, Est-beta, Amy, most of the individuals are heterozygotes. At the other extreme , Mdh, aGpdh, Acph, few individuals are heterozygotes. For Mdh, we have measured the thermostability at 53 degrees C. No more genetic variation was found. We have measured the amount of genetic differentiation between different local populations. The result showed that there is no relationship between geographical distance and genetic distance. The results are discussed in the light of the continuing controversy over selection and natural theories of genetic variation. We think that both selection and stochastic processes must operate simultaneously in most systems.