1,305 research outputs found
A Spitzer Five-Band Analysis of the Jupiter-Sized Planet TrES-1
With an equilibrium temperature of 1200 K, TrES-1 is one of the coolest hot
Jupiters observed by {\Spitzer}. It was also the first planet discovered by any
transit survey and one of the first exoplanets from which thermal emission was
directly observed. We analyzed all {\Spitzer} eclipse and transit data for
TrES-1 and obtained its eclipse depths and brightness temperatures in the 3.6
{\micron} (0.083 % {\pm} 0.024 %, 1270 {\pm} 110 K), 4.5 {\micron} (0.094 %
{\pm} 0.024 %, 1126 {\pm} 90 K), 5.8 {\micron} (0.162 % {\pm} 0.042 %, 1205
{\pm} 130 K), 8.0 {\micron} (0.213 % {\pm} 0.042 %, 1190 {\pm} 130 K), and 16
{\micron} (0.33 % {\pm} 0.12 %, 1270 {\pm} 310 K) bands. The eclipse depths can
be explained, within 1 errors, by a standard atmospheric model with
solar abundance composition in chemical equilibrium, with or without a thermal
inversion. The combined analysis of the transit, eclipse, and radial-velocity
ephemerides gives an eccentricity , consistent
with a circular orbit. Since TrES-1's eclipses have low signal-to-noise ratios,
we implemented optimal photometry and differential-evolution Markov-chain Monte
Carlo (MCMC) algorithms in our Photometry for Orbits, Eclipses, and Transits
(POET) pipeline. Benefits include higher photometric precision and \sim10 times
faster MCMC convergence, with better exploration of the phase space and no
manual parameter tuning.Comment: 17 pages, Accepted for publication in Ap
Integrin-linked kinase localizes to the centrosome and regulates mitotic spindle organization
Integrin-linked kinase (ILK) is a serine-threonine kinase and scaffold protein with well defined roles in focal adhesions in integrin-mediated cell adhesion, spreading, migration, and signaling. Using mass spectrometry–based proteomic approaches, we identify centrosomal and mitotic spindle proteins as interactors of ILK. α- and β-tubulin, ch-TOG (XMAP215), and RUVBL1 associate with ILK and colocalize with it to mitotic centrosomes. Inhibition of ILK activity or expression induces profound apoptosis-independent defects in the organization of the mitotic spindle and DNA segregation. ILK fails to localize to the centrosomes of abnormal spindles in RUVBL1-depleted cells. Additionally, depletion of ILK expression or inhibition of its activity inhibits Aurora A–TACC3/ch-TOG interactions, which are essential for spindle pole organization and mitosis. These data demonstrate a critical and unexpected function for ILK in the organization of centrosomal protein complexes during mitotic spindle assembly and DNA segregation
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Group 2 Innate Lymphoid Cells Are Redundant in Experimental Renal Ischemia-Reperfusion Injury.
Acute kidney injury (AKI) can be fatal and is a well-defined risk factor for the development of chronic kidney disease. Group 2 innate lymphoid cells (ILC2s) are innate producers of type-2 cytokines and are critical regulators of homeostasis in peripheral organs. However, our knowledge of their function in the kidney is relatively limited. Recent evidence suggests that increasing ILC2 numbers by systemic administration of recombinant interleukin (IL)-25 or IL-33 protects against renal injury. Whilst ILC2s can be induced to protect against ischemic- or chemical-induced AKI, the impact of ILC2 deficiency or depletion on the severity of renal injury is unknown. Firstly, the phenotype and location of ILC2s in the kidney was assessed under homeostatic conditions. Kidney ILC2s constitutively expressed high levels of IL-5 and were located in close proximity to the renal vasculature. To test the functional role of ILC2s in the kidney, an experimental model of renal ischemia-reperfusion injury (IRI) was used and the severity of injury was assessed in wild-type, ILC2-reduced, ILC2-deficient, and ILC2-depleted mice. Surprisingly, there were no differences in histopathology, collagen deposition or mRNA expression of injury-associated (Lcn2), inflammatory (Cxcl1, Cxcl2, and Tnf) or extracellular matrix (Col1a1, Fn1) factors following IRI in the absence of ILC2s. These data suggest the absence of ILC2s does not alter the severity of renal injury, suggesting possible redundancy. Therefore, other mechanisms of type 2-mediated immune cell activation likely compensate in the absence of ILC2s. Hence, a loss of ILC2s is unlikely to increase susceptibility to, or severity of AKI
Mitigation of Physical Aging with Mixed Matrix Membranes Based on Cross-Linked PIM-1 Fillers and PIM-1
A low cross-link density (LCD) network-PIM-1, which offers high compatibility with the polymer of intrinsic microporosity PIM-1, is synthesized by a modified PIM-1 polycondensation that combines both a tetrafluoro- and an octafluoro-monomer. To maximize the advantages of utilizing such cross-linked PIM-1 fillers in PIM-1-based mixed matrix membranes (MMMs), a grafting route is used to decorate the LCD-network-PIM-1 (dispersed phase) with PIM-1 chains, to further enhance compatibility with the PIM-1 matrix. Mixed-gas CO2/CH4 (1:1, v/v) separation results over 160 days of membrane aging confirm the success of a relatively short (24 h) grafting reaction in improving the initial CO2 separation performance, as well as hindering the aging of PIM-1/grafted-LCD-network-PIM-1 MMMs. For MMMs based on a 24 h grafting route, all the gas separation data surpass the 2008 Robeson upper bound by a significant margin, and the 160-day aged membranes show only 29% reduction from the initial CO2 permeability, which is substantially less than the equivalent losses of nearly 70% and 48% for PIM-1 and traditionally fabricated MMMs counterparts, respectively. These results demonstrate the potential of network-PIM components for obtaining much more stable gas separation performance over extended periods of time
Intercomparison of Satellite-Derived Snow-Cover Maps
In anticipation of the launch of the Earth Observing System (EOS) Terra, and the PM-1 spacecraft in 1999 and 2000, respectively, efforts are ongoing to determine errors of satellite-derived snow-cover maps. EOS Moderate Resolution Imaging Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer-E (AMSR-E) snow-cover products will be produced. For this study we compare snow maps covering the same study area acquired from different sensors using different snow- mapping algorithms. Four locations are studied: 1) southern Saskatchewan; 2) a part of New England (New Hampshire, Vermont and Massachusetts) and eastern New York; 3) central Idaho and western Montana; and 4) parts of North and South Dakota. Snow maps were produced using a prototype MODIS snow-mapping algorithm used on Landsat Thematic Mapper (TM) scenes of each study area at 30-m and when the TM data were degraded to 1 -km resolution. National Operational Hydrologic Remote Sensing Center (NOHRSC) 1 -km resolution snow maps were also used, as were snow maps derived from 1/2 deg. x 1/2 deg. resolution Special Sensor Microwave Imager (SSM/1) data. A land-cover map derived from the International Geosphere-Biosphere Program (IGBP) land-cover map of North America was also registered to the scenes. The TM, NOHRSC and SSM/I snow maps, and land-cover maps were compared digitally. In most cases, TM-derived maps show less snow cover than the NOHRSC and SSM/I maps because areas of incomplete snow cover in forests (e.g., tree canopies, branches and trunks) are seen in the TM data, but not in the coarser-resolution maps. The snow maps generally agree with respect to the spatial variability of the snow cover. The 30-m resolution TM data provide the most accurate snow maps, and are thus used as the baseline for comparison with the other maps. Comparisons show that the percent change in amount of snow cover relative to the 3 0-m resolution TM maps is lowest using the TM I -km resolution maps, ranging from 0 to 40%. The highest percent change (less than 100%) is found in the New England study area, probably due to the presence of patchy snow cover. A scene with patchy snow cover is more difficult to map accurately than is a scene with a well-defined snowline such as is found on the North and South Dakota scene where the percent change ranged from 0 to 40%. There are also some important differences in the amount of snow mapped using the two different SSM/I algorithms because they utilize different channels
High gas permeability in aged superglassy membranes with nanosized UiO-66-NH2/cPIM-1 network fillers
Superglassy membranes synthesised by polymers of intrinsic microporosity (PIMs) suffer from physical aging and show poor gas permeance over time, especially thin membranes, due to the fast rearrangement of nonequilibrium polymer chains. Herein, we constructed a novel PIM‐1 thin film nanocomposite membrane (TFN) using nanosized UiO‐66−NH2 (≈10 nm)/carboxylated PIM‐1 (cPIM‐1) as the composite filler. Unlike conventional fillers, which interact with the polymer only via the surface, the UiO‐66−NH2/cPIM‐1 forms a stable three‐dimensional (3D) network intertwining with the polymer chains, being very effective to impede chain relaxation, and thus physical aging. Nanosizing of UiO‐66−NH2 was achieved by regulating the nucleation kinetics using carbon quantum dots (CQD) during the synthesis. This led to increased surface area, and hence more functional groups to bond with cPIM‐1 (via hydrogen bonding between −NH2 and −COOH groups), which also improved interfacial compatibility between the 3D network and polymer chains avoiding defect formation. As a result, the novel TFN showed significantly improved performance in gas separation along with reduced aging (i.e. ≈6 % loss in CO2 permeability over 63 days); the aged membranes had a CO2 permeance of 2504 GPU and ideal selectivity values of 37.2 and 23.8 for CO2/N2 and CO2/CH4, respectively
Molecular Mobility and Gas Transport Properties of Mixed Matrix Membranes Based on PIM-1 and a Phosphinine Containing Covalent Organic Framework
Polymers with intrinsic microporosity (PIMs) are gaining attention as gas separation membranes. Nevertheless, they face limitations due to their pronounced physical aging. In this study, a covalent organic framework containing λ5-phosphinine moieties, CPSF-EtO, was incorporated as a nanofiller (concentration range 0–10 wt %) into a PIM-1 matrix forming dense films with a thickness of ca. 100 μm. The aim of the investigation was to investigate possible enhancements of gas transport properties and mitigating effects on physical aging. The incorporation of the nanofiller occurred on an nanoaggregate level with domains up to 100 nm, as observed by T-SEM and confirmed by X-ray scattering. Moreover, the X-ray data show that the structure of the microporous network of the PIM-1 matrix is changed by the nanofiller. As molecular mobility is fundamental for gas transport as well as for physical aging, the study includes dielectric investigations of pure PIM-1 and PIM-1/CPSF-EtO mixed matrix membranes to establish a correlation between the molecular mobility and the gas transport properties. Using the time-lag method, the gas permeability and the permselectivity were determined for N2, O2, CH4, and CO2 for samples with variation in filler content. A significant increase in the permeability of CH4 and CO2 (50% increase compared to pure PIM-1) was observed for a concentration of 5 wt % of the nanofiller. Furthermore, the most pronounced change in the permselectivity was found for the gas pair CO2/N2 at a filler concentration of 7 wt %
Correlates of HIV, HBV, HCV and syphilis infections among prison inmates and officers in Ghana: A national multicenter study
<p>Abstract</p> <p>Background</p> <p>Prisons are known to be high-risk environments for the spread of bloodborne and sexually transmitted infections. Prison officers are considered to have an intermittent exposure potential to bloodborne infectious diseases on the job, however there has been no studies on the prevalence of these infections in prison officers in Ghana.</p> <p>Methods</p> <p>A national multicenter cross-sectional study was undertaken on correlates of human immunodeficiency virus (HIV), hepatitis B virus (HBV), hepatitis C virus (HCV), and syphilis infections in sample of prison inmates and officers from eight of ten regional central prisons in Ghana. A total of 1366 inmates and 445 officers were enrolled between May 2004 and December 2005. Subjects completed personal risk-factor questionnaire and provided blood specimens for unlinked anonymous testing for presence of antibodies to HIV, HCV and <it>Treponema pallidum</it>; and surface antigen of HBV (HBsAg). These data were analyzed using both univariate and multivariate techniques.</p> <p>Results</p> <p>Almost 18% (1336) of 7652 eligible inmates and 21% (445) of 2139 eligible officers in eight study prisons took part. Median ages of inmates and officers were 36.5 years (range 16–84) and 38.1 years (range 25–59), respectively. Among inmates, HIV seroprevalence was 5.9%, syphilis seroprevalence was 16.5%, and 25.5% had HBsAg. Among officers tested, HIV seroprevalence was 4.9%, HCV seroprevalence was 18.7%, syphilis seroprevalence was 7.9%, and 11.7% had HBsAg. Independent determinants for HIV, HBV and syphilis infections among inmates were age between 17–46, being unmarried, being illiterate, female gender, being incarcerated for longer than median time served of 36 months, history of homosexuality, history of intravenous drug use, history of sharing syringes and drug paraphernalia, history of participation in paid sexual activity, and history of sexually transmitted diseases. Independent determinants for HIV, HBV, HCV and syphilis infections among officers were age between 25–46, fale gender, being unmarried, being employed in prison service for longer than median duration of employment of 10 years, and history of sexually transmitted diseases.</p> <p>Conclusion</p> <p>The comparably higher prevalence of HIV, HBV, HCV and syphilis in prison inmates and officers in Ghana suggests probable occupational related transmission. The implementation of infection control practices and risk reduction programs targeted at prison inmates and officers in Ghana is urgently required to address this substantial exposure risk.</p
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