1,628 research outputs found

    Maternal urinary bisphenol a during pregnancy and maternal and neonatal thyroid function in the CHAMACOS study.

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    BackgroundBisphenol A (BPA) is widely used in the manufacture of polycarbonate plastic bottles, food and beverage can linings, thermal receipts, and dental sealants. Animal and human studies suggest that BPA may disrupt thyroid function. Although thyroid hormones play a determinant role in human growth and brain development, no studies have investigated relations between BPA exposure and thyroid function in pregnant women or neonates.ObjectiveOur goal was to evaluate whether exposure to BPA during pregnancy is related to thyroid hormone levels in pregnant women and neonates.MethodsWe measured BPA concentration in urine samples collected during the first and second half of pregnancy in 476 women participating in the CHAMACOS (Center for the Health Assessment of Mothers and Children of Salinas) study. We also measured free thyroxine (T4), total T4, and thyroid-stimulating hormone (TSH) in women during pregnancy, and TSH in neonates.ResultsAssociations between the average of the two BPA measurements and maternal thyroid hormone levels were not statistically significant. Of the two BPA measurements, only the one taken closest in time to the TH measurement was significantly associated with a reduction in total T4 (β = -0.13 µg/dL per log2 unit; 95% CI: -0.25, 0.00). The average of the maternal BPA concentrations was associated with reduced TSH in boys (-9.9% per log2 unit; 95% CI: -15.9%, -3.5%) but not in girls. Among boys, the relation was stronger when BPA was measured in the third trimester of pregnancy and decreased with time between BPA and TH measurements.ConclusionResults suggest that exposure to BPA during pregnancy is related to reduced total T4 in pregnant women and decreased TSH in male neonates. Findings may have implications for fetal and neonatal development

    Levels and Determinants of DDT and DDE Exposure in the VHEMBE Cohort.

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    BackgroundAlthough indoor residual spraying (IRS) is an effective tool for malaria control, its use contributes to high insecticide exposure in sprayed communities and raises concerns about possible unintended health effects.ObjectiveThe Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) is a birth cohort study initiated in 2012 to characterize prenatal exposure to IRS insecticides and exposures' impacts on child health and development in rural South Africa.MethodsIn this report, we describe the VHEMBE cohort and dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) serum concentrations measured in VHEMBE mothers when they presented for delivery. In addition, we applied a causal inference framework to estimate the potential reduction in population-level p,p'-DDT and p,p'-DDE serum concentrations under five hypothetical interventions. A total of 751 mothers were enrolled.ResultsSerum concentrations of p,p' isomers of DDT and DDE were above the limit of detection (LOD) in ≥98% of the samples, whereas the o,p' isomers were above the LOD in at least 80% of the samples. Median (interquartile range) p,p'-DDT and p,p'-DDE serum concentrations for VHEMBE cohort participants were 55.3 (19.0-259.3) and 242.2 (91.8-878.7) ng/g-lipid, respectively. Mothers reporting to have lived in a home sprayed with DDT for malaria control had ~5-7 times higher p,p'-DDT and p,p'-DDE serum concentrations than those who never lived in a home sprayed with DDT. Of the five potential interventions tested, we found increasing access to water significantly reduced p,p'-DDT exposure and increasing the frequency of household wet mopping significantly reduced p,p'-DDT and p,p'-DDE exposure.ConclusionOur findings suggest that several intervention approaches may reduce DDT/DDE exposure in pregnant women living in IRS communities. https://doi.org/10.1289/EHP353

    Experimental Investigation into the Radar Anomalies on the Surface of Venus

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    Radar mapping of thc surface of Venus shows areas of high reflectivity (low emissivity) in the Venusian highlands at altitudes between 2.5-4.75 kilometers. The origin of the radar anomalies found in the Venusian highlands remains unclear. Most explanations of the potential causes for these radar anomalies come from theoretical work. Previous studies suggest increased surface roughness or materials with higher dielectric constants as well as surface atmospheric interactions. Several possible candidates of high-dielectric materials are tellurium) ferroelectric materials, and lead or bismuth sulfides. While previous studies have been influential in determining possible sources for the Venus anomalies, only a very few hypotheses have been verified via experimentation. This work intends to experimentally constrain the source of the radar anomalies on Venus. This study proposes to investigate four possible materials that could potentially cause the high reflectivities on the surface of Venus and tests their behavior under simulated Venusian conditions

    Imaging Electron Wave Functions Inside Open Quantum Rings

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    Combining Scanning Gate Microscopy (SGM) experiments and simulations, we demonstrate low temperature imaging of electron probability density Ψ2(x,y)|\Psi|^{2}(x,y) in embedded mesoscopic quantum rings (QRs). The tip-induced conductance modulations share the same temperature dependence as the Aharonov-Bohm effect, indicating that they originate from electron wavefunction interferences. Simulations of both Ψ2(x,y)|\Psi|^{2}(x,y) and SGM conductance maps reproduce the main experimental observations and link fringes in SGM images to Ψ2(x,y)|\Psi|^{2}(x,y).Comment: new titl

    Unveiling the intruder deformed 02+^+_2 state in 34^{34}Si

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    The 02+^+_2 state in 34^{34}Si has been populated at the {\sc Ganil/Lise3} facility through the β\beta-decay of a newly discovered 1+^+ isomer in 34^{34}Al of 26(1) ms half-life. The simultaneous detection of e+ee^+e^- pairs allowed the determination of the excitation energy E(02+^+_2)=2719(3) keV and the half-life T1/2_{1/2}=19.4(7) ns, from which an electric monopole strength of ρ2\rho^2(E0)=13.0(0.9)×103\times10^{-3} was deduced. The 21+^+_1 state is observed to decay both to the 01+^+_1 ground state and to the newly observed 02+^+_2 state (via a 607(2) keV transition) with a ratio R(21+^+_101+/21+\rightarrow0^+_1/2^+_102+\rightarrow0^+_2)=1380(717). Gathering all information, a weak mixing with the 01+^+_1 and a large deformation parameter of β\beta=0.29(4) are found for the 02+^+_2 state, in good agreement with shell model calculations using a new {\sc sdpf-u-mix} interaction allowing \textit{np-nh} excitations across the N=20 shell gap.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter

    Giant slip lengths of a simple fluid at vibrating solid interfaces

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    It has been shown recently [PRL 102, 254503 (2009)] that in the plane-plane configuration a mechanical resonator vibrating close to a rigid wall in a simple fluid can be overdamped to a frozen regime. Here, by solving analytically the Navier Stokes equations with partial slip boundary conditions at the solid fluid interface, we develop a theoretical approach justifying and extending these earlier findings. We show in particular that in the perfect slip regime the above mentioned results are, in the plane-plane configuration, very general and robust with respect to lever geometry considerations. We compare the results with those obtained previously for the sphere moving perpendicularly and close to a plane in a simple fluid and discuss in more details the differences concerning the dependence of the friction forces with the gap distance separating the moving object (i.e., plane or sphere) from the fixed plane. Finally, we show that the submicron fluidic effect reported in the reference above, and discussed further in the present work, can have dramatic implications in the design of nano-electromechanical systems (NEMS).Comment: submitted to PRE (see also PRL 102, 254503 (2009)
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