303 research outputs found

    Integrated Focal Plane Arrays for Millimeter-wave Astronomy

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    We are developing focal plane arrays of bolometric detectors for sub-millimeter and millimeter-wave astrophysics. We propose a flexible array architecture using arrays of slot antennae coupled via low-loss superconducting Nb transmission line to microstrip filters and antenna-coupled bolometers. By combining imaging and filtering functions with transmission line, we are able to realize unique structures such as a multi-band polarimeter and a planar, dispersive spectrometer. Micro-strip bolometers have significantly smaller active volume than standard detectors with extended absorbers, and can realize higher sensitivity and speed of response. The integrated array has natural immunity to stray radiation or spectral leaks, and minimizes the suspended mass operating at 0.1 - 0.3 K. We also discuss future space-borne spectroscopy and polarimetry applications

    The use of fluorescent probes to characterize conformational changes in the interaction between vitronectin and plasminogen activator inhibitor-1

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    Plasminogen activator inhibitor-1 (PAI-1), the primary inhibitor of tissue-type plasminogen activator and urokinase, is known to convert readily to a latent form by insertion of the reactive center loop into a central β- sheet. Interaction with vitronectin stabilizes PAI-1 and decreases the rate of conversion to the latent form, but conformational effects of vitronectin on the reactive center loop of PAI-1 have not been documented. Mutant forms of PAI-1 were designed with a cysteine substitution at either position P1\u27 or P9 of the reactive center loop. Labeling of the unique cysteine with a sulfhydryl-reactive fluorophore provides a probe that is sensitive to vitronectin binding. Results indicate that the scissile P1-P1\u27 bond of PAI-1 is more solvent exposed upon interaction with vitronectin, whereas the N- terminal portion of the reactive loop does not experience a significant change in its environment. These results were complemented by labeling vitronectin with an arginine-specific coumarin probe which compromises heparin binding but does not interfere with PAI-1 binding to the protein. Dissociation constants of approximately 100 nM are calculated for the vitronectin/PAI-1 interaction from titrations using both fluorescent probes. Furthermore, experiments in which PAI-1 failed to compete with heparin for binding to vitronectin argue for separate binding sites for the two ligands on vitronectin

    Bis(μ-dithieno[3,2-b:2′,3′-d]thio­phene-2,6-dicarboxyl­ato-κ2 O 2:O 6)bis­[bis­(1,10-phenanthroline-κ2 N,N′)cobalt(II)] dimethyl­formamide disolvate

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    The asymmetric unit of the title compound, [Co2(C10H2O4S3)2(C12H8N2)4]·2C3H7NO, contains one half of the formula unit, with the rest generated by inversion. The cobalt ion sits in a slightly distorted octa­hedral environment and is ligated to four N atoms of two 1,10-phenanthroline molecules and to two O atoms of two dithieno[3,2-b:2′,3′-d]thio­phene-2,6-dicarb­oxy­l­ate anions. The anions act as bridges between the CoII centers

    Transition-edge superconducting antenna-coupled bolometer

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    We report test results for a single pixel antenna-coupled bolometric detector. Our device consists of a dual slot microstrip antenna coupled to an Al/Ti/Au voltage-biased transition edge superconducting bolometer (TES). The coupling architecture involves propagating the signal along superconducting microstrip lines and terminating the lines at a normal metal resistor colocated with a TES on a thermally isolated island. The device, which is inherently polarization sensitive, is optimized for 140 GHz band measurements. In the thermal bandwidth of the TES, we measure a noise equivalent power of 2.0 × 10^(-17) W/√Hz in dark tests that agrees with calculated NEP including only contributions from thermal, Johnson and amplifier noise. We do not measure any excess noise at frequencies between 1 and 200 Hz. We measure a thermal conductance G ~5.5 × 10^(-11) W/K. We measure a thermal time constant as low as 437μs at 3μV bias when stimulating the TES directly using an LED

    Stillbirths: Where? When? Why? How to make the data count?

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    Despite increasing attention and investment for maternal, neonatal, and child health, stillbirths remain invisible-not counted in the Millennium Development Goals, nor tracked by the UN, nor in the Global Burden of Disease metrics. At least 2·65 million stillbirths (uncertainty range 2·08 million to 3·79 million) were estimated worldwide in 2008 (≥1000 g birthweight or ≥28 weeks of gestation). 98% of stillbirths occur in low-income and middle-income countries, and numbers vary from 2·0 per 1000 total births in Finland to more than 40 per 1000 total births in Nigeria and Pakistan. Worldwide, 67% of stillbirths occur in rural families, 55% in rural sub-Saharan Africa and south Asia, where skilled birth attendance and caesarean sections are much lower than that for urban births. In total, an estimated 1·19 million (range 0·82 million to 1·97 million) intrapartum stillbirths occur yearly. Most intrapartum stillbirths are associated with obstetric emergencies, whereas antepartum stillbirths are associated with maternal infections and fetal growth restriction. National estimates of causes of stillbirths are scarce, and multiple (>35) classification systems impede international comparison. Immediate data improvements are feasible through household surveys and facility audit, and improvements in vital registration, including specific perinatal certificates and revised International Classification of Disease codes, are needed. A simple, programme-relevant stillbirth classification that can be used with verbal autopsy would provide a basis for comparable national estimates. A new focus on all deaths around the time of birth is crucial to inform programmatic investment

    Brief motivational enhancement intervention to prevent or reduce postpartum alcohol use: a single-blinded, randomized controlled effectiveness trial

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    AIMS: The aim of this study is to assess the effect of brief motivational enhancement intervention postpartum alcohol use. DESIGN: This study is a single-blinded, randomized controlled effectiveness trial in which pregnant women were assigned to receive usual care or up to 5 face-to-face brief motivational enhancement sessions lasting 10-30 minutes each and occurring at study enrollment, 4 and 8 weeks after enrollment, 32 weeks of gestation, and 6 weeks postpartum. SETTING: The setting is in a large, urban, obstetrics clinic. PARTICIPANTS: Participants were women who were \u3e/= 18 years old,gestation, and consumed alcohol during pregnancy. Of 3438 women screened, 330 eligible women were assigned to usual care (n = 165) or intervention (n=165). Due to missing data, we analyzed 125 in the intervention group and 126 in the usual care group. MEASUREMENTS: The measurements were the proportion of women with any alcohol use and the number of drinks per day, reported via follow-up telephone interviews at 4 and 8 weeks after enrollment, 32 weeks of gestation, and 6 weeks, 6 months, and 12 months postpartum. FINDINGS: In random effects models adjusted for confounders, the intervention group was less likely to use any alcohol (odds ratio 0.50; 95% confidence interval [CI], 0.23-1.09; P=0.08) and consumed fewer drinks per day (coefficient -0.11; 95% CI -0.23-0.01; P=0.07) than, the usual care group in the postpartum period but these differences were non-significant. Missing data during the prenatal period prevented us from modeling prenatal alcohol use. CONCLUSIONS: Brief motivational enhancement intervention delivered in an obstetrical outpatient setting did not conclusively decrease alcohol use during the postpartum period
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