Sharp lines in the absorption edge of EuTe and Pb0.1_{0.1}Eu0.9_{0.9}Te in high magnetic fields

The optical absorption spectra in the region of the \fd transition energies of epitaxial layers of of EuTe and \PbEuTe, grown by molecular beam epitaxy, were studied using circularly polarized light, in the Faraday configuration. Under \sigmam polarization a sharp symmetric absorption line (full width at half-maximum 0.041 eV) emerges at the low energy side of the band-edge absorption, for magnetic fields intensities greater than 6 T. The absorption line shows a huge red shift (35 meV/T) with increasing magnetic fields. The peak position of the absorption line as a function of magnetic field is dominated by the {\em d-f} exchange interaction of the excited electron and the \Euion spins in the lattice. The {\em d-f} exchange interaction energy was estimated to be $J_{df}S=0.15\pm 0.01$ eV. In \PbEuTe the same absorption line is detected, but it is broader, due to alloy disorder, indicating that the excitation is localized within a finite radius. From a comparison of the absorption spectra in EuTe and \PbEuTe the characteristic radius of the excitation is estimated to be $\sim 10$\AA.Comment: Journal of Physics: Condensed Matter (2004, at press

Body fatness and sex steroid hormone concentrations in US men: results from NHANES III

Objective: Obesity is associated with a variety of chronic diseases, including cancer, which may partly be explained by its influence on sex steroid hormone concentrations. Whether different measures of obesity, i.e., body mass index (BMI), waist circumference, and percent body fat were differentially associated with circulating levels of sex steroid hormones was examined in 1,265 men, aged 20-90+years old, attending the morning examination session of the Third National Health and Nutrition Examination Survey (NHANES III). Materials and methods: Serum hormones were measured by immunoassay. Weight, height, and waist circumference were measured by trained staff. Percent body fat was estimated from bioelectrical impedance. Multivariate linear regression was used to estimate associations between body fatness measures and hormone levels. Results: Total and free testosterone and sex hormone binding globulin concentrations decreased, whereas total and free estradiol increased with increasing BMI, waist circumference, and percent body fat (all p trend<0.05). The magnitude of change in these hormones was similar for a one-quartile increase in each body fatness measure. Conclusion: Measured BMI, waist circumference, and percent body fat led to similar inferences about their association with hormone levels in me

Magnetic correlations and quantum criticality in the insulating antiferromagnetic, insulating spin liquid, renormalized Fermi liquid, and metallic antiferromagnetic phases of the Mott system V_2O_3

Magnetic correlations in all four phases of pure and doped vanadium sesquioxide V_2O_3 have been examined by magnetic thermal neutron scattering. While the antiferromagnetic insulator can be accounted for by a Heisenberg localized spin model, the long range order in the antiferromagnetic metal is an incommensurate spin-density-wave, resulting from a Fermi surface nesting instability. Spin dynamics in the strongly correlated metal are dominated by spin fluctuations in the Stoner electron-hole continuum. Furthermore, our results in metallic V_2O_3 represent an unprecedentedly complete characterization of the spin fluctuations near a metallic quantum critical point, and provide quantitative support for the SCR theory for itinerant antiferromagnets in the small moment limit. Dynamic magnetic correlations for energy smaller than k_BT in the paramagnetic insulator carry substantial magnetic spectral weight. However, the correlation length extends only to the nearest neighbor distance. The phase transition to the antiferromagnetic insulator introduces a sudden switching of magnetic correlations to a different spatial periodicity which indicates a sudden change in the underlying spin Hamiltonian. To describe this phase transition and also the unusual short range order in the paramagnetic state, it seems necessary to take into account the orbital degrees of freedom associated with the degenerate d-orbitals at the Fermi level in V_2O_3.Comment: Postscript file, 24 pages, 26 figures, 2 tables, accepted by Phys. Rev.

A common haplotype lowers PU.1 expression in myeloid cells and delays onset of Alzheimer's disease

A genome-wide survival analysis of 14,406 Alzheimer's disease (AD) cases and 25,849 controls identified eight previously reported AD risk loci and 14 novel loci associated with age at onset. Linkage disequilibrium score regression of 220 cell types implicated the regulation of myeloid gene expression in AD risk. The minor allele of rs1057233 (G), within the previously reported CELF1 AD risk locus, showed association with delayed AD onset and lower expression of SPI1 in monocytes and macrophages. SPI1 encodes PU.1, a transcription factor critical for myeloid cell development and function. AD heritability was enriched within the PU.1 cistrome, implicating a myeloid PU.1 target gene network in AD. Finally, experimentally altered PU.1 levels affected the expression of mouse orthologs of many AD risk genes and the phagocytic activity of mouse microglial cells. Our results suggest that lower SPI1 expression reduces AD risk by regulating myeloid gene expression and cell function

Netrins and neogenin promote myotube formation

Differentiation of skeletal myoblasts into multinucleated myotubes is a multistep process orchestrated by several families of transcription factors, including myogenic bHLH and NFAT proteins. The activities of these factors and formation of myotubes are regulated by signal transduction pathways, but few extracellular factors that might initiate such signals have been identified. One exception is a cell surface complex containing promyogenic Ig superfamily members (CDO and BOC) and cadherins. Netrins and their receptors are established regulators of axon guidance, but little is known of their function outside the nervous system. We report here that myoblasts express the secreted factor netrin-3 and its receptor, neogenin. These proteins stimulate myotube formation and enhance myogenic bHLH- and NFAT-dependent transcription. Furthermore, neogenin binds to CDO in a cis fashion, and myoblasts lacking CDO are defective in responding to recombinant netrin. It is proposed that netrin-3 and neogenin may promote myogenic differentiation by an autocrine mechanism as components of a higher order complex of several promyogenic cell surface proteins

Small-for-Gestational Age Prevalence Risk Factors in Central Appalachian States with Mountain-top Mining.

OBJECTIVES: To identify risk factors for small-for-gestational age (SGA) for counties in central Appalachian states (Kentucky (KY), Tennessee (TN), Virginia (VA), and West Virginia (WV)) with varied coal mining activities. MATERIAL AND METHODS: Live birth certificate files (1990-2002) were used for obtaining SGA prevalence rates for mothers based on the coal mining activities of their counties of residence, mountain-top mining (MTM) activities, underground mining activities but no mountain-top mining activity (non-MTM), or having no mining activities (non-mining). Co-variable information, including maternal tobacco use, was also obtained from the live birth certificate. Adjusted odds ratios were obtained using multivariable logistic regression comparing SGA prevalence rates for counties with coal mining activities to those without coal mining activities and comparing SGA prevalence rates for counties with coal mining activities for those with and without mountain-top mining activities. Comparisons were also made among those who had reported tobacco use and those who had not. RESULTS: Both tobacco use prevalence and SGA prevalence were significantly greater for mining counties than for non-mining counties and for MTM counties than for non-MTM counties. Adjustment for tobacco use alone explained 50% of the increased SGA risk for mining counties and 75% of the risk for MTM counties, including demographic pre-natal care co-variables that explained 75% of the increased SGA risk for mining counties and 100% of the risk for MTM. The increased risk of SGA was limited to the third trimester births among tobacco users and independent of the mining activities of their counties of residence. CONCLUSIONS: This study demonstrates that the increased prevalence of SGA among residents of counties with mining activity was primarily explained by the differences in maternal tobacco use prevalence, an effect that itself was gestational-age dependent. Self-reported tobacco use marked the population at the increased risk for SGA in central Appalachian states. Int J Occup Med Environ Health 2018;31(1):11-23

Search for correlation between geomagnetic disturbances and mortality

Statistical evaluation of death rates in the U.S.A. from heart diseases or stroke did not show any correlation with measured geomagnetic pulsations and thus do not support a claimed relationship between geomagnetic activity and mortality rates to low frequency fluctuations of the earth's magnetic field

Arsenic in Drinking Water and Lung Cancer Mortality in the United States: An Analysis Based on US Counties and 30 Years of Observation (1950-1979).

Background. To examine whether the US EPA (2010) lung cancer risk estimate derived from the high arsenic exposures (10-934 µg/L) in southwest Taiwan accurately predicts the US experience from low arsenic exposures (3-59 µg/L). Methods. Analyses have been limited to US counties solely dependent on underground sources for their drinking water supply with median arsenic levels of ≥3 µg/L. Results. Cancer risks (slopes) were found to be indistinguishable from zero for males and females. The addition of arsenic level did not significantly increase the explanatory power of the models. Stratified, or categorical, analysis yielded relative risks that hover about 1.00. The unit risk estimates were nonpositive and not significantly different from zero, and the maximum (95% UCL) unit risk estimates for lung cancer were lower than those in US EPA (2010). Conclusions. These data do not demonstrate an increased risk of lung cancer associated with median drinking water arsenic levels in the range of 3-59 µg/L. The upper-bound estimates of the risks are lower than the risks predicted from the SW Taiwan data and do not support those predictions. These results are consistent with a recent metaregression that indicated no increased lung cancer risk for arsenic exposures below 100-150 µg/L