1,048 research outputs found

    Mortality in young adults following in utero and childhood exposure to arsenic in drinking water.

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    BackgroundBeginning in 1958, the city of Antofagasta in northern Chile was exposed to high arsenic concentrations (870 ”g/L) when it switched water sources. The exposure abruptly stopped in 1970 when an arsenic-removal plant commenced operations. A unique exposure scenario like this--with an abrupt start, clear end, and large population (125,000 in 1970), all with essentially the same exposure--is rare in environmental epidemiology. Evidence of increased mortality from lung cancer, bronchiectasis, myocardial infarction, and kidney cancer has been reported among young adults who were in utero or children during the high-exposure period.ObjectiveWe investigated other causes of mortality in Antofagasta among 30- to 49-year-old adults who were in utero or ≀ 18 years of age during the high-exposure period.MethodsWe compared mortality data between Antofagasta and the rest of Chile for people 30-49 years of age during 1989-2000. We estimated expected deaths from mortality rates in all of Chile, excluding Region II where Antofagasta is located, and calculated standardized mortality ratios (SMRs).ResultsWe found evidence of increased mortality from bladder cancer [SMR = 18.1; 95% confidence interval (CI): 11.3, 27.4], laryngeal cancer (SMR = 8.1; 95% CI: 3.5, 16.0), liver cancer (SMR = 2.5; 95% CI: 1.6, 3.7), and chronic renal disease (SMR = 2.0; 95% CI: 1.5, 2.8).ConclusionsTaking together our findings in the present study and previous evidence of increased mortality from other causes of death, we conclude that arsenic in Antofagasta drinking water has resulted in the greatest increases in mortality in adults < 50 years of age ever associated with early-life environmental exposure

    Compression of glycolide-h4 to 6 GPa

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    This study details the structural characterisation of glycolide-h4 as a function of pressure to 6 GPa using neutron powder diffraction on the PEARL instrument at ISIS Neutron and Muon source. Glycolide-h4, rather than its deuterated isotopologue, was used in this study due to the difficulty of deuteration. The low-background afforded by Zirconia-Toughened Alumina (ZTA) anvils nevertheless enabled the collection of data suitable for structural analysis to be obtained to a pressure of 5 GPa. Glycolide-h4 undergoes a reconstructive phase transition at 0.15 GPa to a previously identified, form-II, which is stable to 6 GPa

    Combined micro-Fourier transform infrared (FTIR) spectroscopy and micro-Raman spectroscopy of Proterozoic acritarchs: A new approach to Paleobiology

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    Abstract Micro-scale analytical techniques permit correlation of chemistry with morphology of individual Proterozoic acritarchs (organic-walled microfossils), and thus provide new approaches for elucidating their biological affinities. A combination of micro-Fourier transform infrared (FTIR) spectroscopy and laser micro-Raman spectroscopy was used to investigate the organic structure and composition of individual acritarchs. Well preserved Neoproterozoic acritarchs from the Tanana Formation, Australia (ca. 590-565 Ma), and Mesoproterozoic acritarchs from the Roper Group (1.5-1.4 Ga), Australia, and Ruyang Group, China (1.4-1.3 Ga, age poorly resolved but certainly >1000 Ma and <1625 Ma) have thermal maturities that range from immature to oil window. FTIR spectra of Tanarium conoideum from the Tanana Formation contain intense aliphatic C H stretching bands in the 2900 cm −1 region relative to the C C aromatic ring stretching band at 1600 cm −1 . This FTIR spectrum is consistent with the FTIR spectra obtained from algaenans isolated from extant chlorophyte and eustigmatophyte microalgae. FTIR spectra of Leiosphaeridia sp. from the Tanana Formation contain a less intense aliphatic C H stretching band relative to the C C aromatic ring stretching band. By comparison, the spectra acquired from the Mesoproterozoic acritarchs were dominated by C C aromatic ring stretching bands at 1600 cm −1 relative to moderate-weak CH 3 terminal groups (1345 cm −1 ), C H aliphatic stretching (3000-2700 cm −1 ), and C O (1710 cm −1 ), although some differences in biopolymer composition occurred between species. Curve-fitting of the aliphatic C H x stretching region provides greater insight into the aliphatic structures of the acritarchs. The CH 2 /CH 3 intensity ratio can be used to assess the relative chain length and degree of branching. Organic material in the Tanarium conoideum consists of straight long chain hydrocarbons, while the other acritarchs contain hydrocarbons consisting of short chains that are highly branched. In this study it was found that Raman spectroscopy does not provide additional information about biopolymer composition of Proterozoic acritarchs, but rather offers complementary data regarding the aromaticity and degree of saturation of the macromolecular structure of acritarch cysts

    Thin film solar cell inflatable ultraviolet rigidizable deployment hinge

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    A flexible inflatable hinge includes curable resin for rigidly positioning panels of solar cells about the hinge in which wrap around contacts and flex circuits are disposed for routing power from the solar cells to the power bus further used for grounding the hinge. An indium tin oxide and magnesium fluoride coating is used to prevent static discharge while being transparent to ultraviolet light that cures the embedded resin after deployment for rigidizing the inflatable hinge

    NuSTAR reveals the hidden nature of SS433

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    SS433 is the only Galactic binary system known to accrete at highly super-critical rates, analogous to tidal disruption events, and needed to explain the mass of some high redshift quasars. Probing the inner regions of SS433 in the X-rays is crucial to understanding this system, and super-critical accretion in general, but has not yet been possible due to obscuration. NuSTAR observed SS433 in the hard X-ray band across multiple phases of its super-orbital precession period. Spectral-timing tools have allowed us to confirm that the hard X-ray emission from the inner regions is scattered towards us by the walls of the wind-cone. By comparing to numerical models, we determine an intrinsic X-ray luminosity of >= 3x10^37 erg/s and that, if viewed face on, the apparent luminosity would be > 1x10^39 erg/s, confirming its long-suspected nature as an ultraluminous X-ray source (ULX). A lag due to absorption by Fe XXV/XXVI in outflowing material travelling at least 0.14-0.29c matches absorption lines seen in ULXs and - in future - will allow us to map a super-critical outflow for the first time.Comment: 24 pages, 8 figures, submitted for publicatio

    Development of a Thin-Film Solar Cell Interconnect for the Powersphere Concept

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    Dual junction amorphous silicon (a-Si) solar cells produced on polyimide substrate have been selected as the best candidate to produce a lightweight solar array for the PowerSphere program. The PowerSphere concept features a space-inflatable, geodetic solar array approximately 0.6 meters in diameter and capable of generating about 20W of electrical power. Trade studies of various wiring concepts and connection methods led to an interconnect design with a copper contact that wraps around the edge, to the back of the solar cell. Applying Plasma Vapor Deposited (PVD) copper film to both sides and the edge of the solar cell produces the wrap around contact. This procedure results in a contact pad on the back of the solar cell, which is then laser welded to a flex circuit material. The flex circuit is constructed of copper in a custom designed routing pattern, and then sandwiched in a Kapton insulation layer. The flex circuit then serves as the primary power distribution system between the solar cells and the spacecraft. Flex circuit material is the best candidate for the wiring harness because it allows for low force deployment of the solar cells by the inflatable hinges on the PowerSphere. An additional frame structure, fabricated and assembled by ILC Dover, will reinforce the wrap around contact-flex blanket connection, thus providing a mechanically robust solar cell interconnect for the PowerSphere multifunctional program. The PowerSphere team will use the wraparound contact design approach as the primary solution for solar cell integration and the flex blanket for power distribution
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