512 research outputs found

    Concentration of submicrometre particles from vehicle emissions near a major road.

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    As part of a program of study to assess the exposure risks related to particulate matter in the outdoor environment, number concentrations of particles from vehicle emissions were measured at increasing distances from a major road. Particles in the size range from 0.015 – 0.697 µm were measured with the Scanning Mobility Particle Sizer (SMPS) and in the size range from 0.5 – 20 µm, with the Aerodynamic Particle Sizer (APS). In addition to number concentration measurements, an approximation of PM2.5 fraction was obtained using a DustTrak (simple photometer). The measurements conducted at distances from the road ranging from 15 to 375 m showed, that for conditions where the wind is blowing directly from the road, the concentration of fine and ultrafine particles decays to around half of the maximum (measured at the closest point to the road) at a distance of approximately 100 - 150 m from the road. For the wind blowing parallel to the road, the reduction to half of the concentration occurs at 50 – 100 m. There is no effect on total particle number concentration at a distance greater than 15 m from the road when the wind is blowing towards the road and away from the sampling points. Total number concentrations of larger particles measured were not significantly higher than the average values for the urban environment, and decrease with distance from the road, reaching about 60% at 150 m from the road for wind from the road. PM2.5 levels also decrease with distance to around 75% for wind from the road and to 65% for wind parallel to the road, at a distance of 375 m

    Anthropometric discriminators of type 2 diabetes among White and Black American adults

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    BACKGROUND: The aim of the present study was to determine the best anthropometric discriminators of type 2 diabetes mellitus (T2DM) among White and Black males and females in a large US sample. METHODS: We used Atherosclerosis Risk in Communities study baseline data (1987–89) from 15 242 participants (1827 with T2DM) aged 45–65 years. Anthropometric measures included a body shape index (ABSI), body adiposity index (BAI), body mass index, waist circumference (WC), waist:height ratio (WHtR), and waist:hip ratio (WHR). All anthropometric measures were standardized to Z-scores. Using logistic regression, odds ratios for T2DM were adjusted for age, physical activity, and family history of T2DM. The Akaike information criterion and receiver operating characteristic C-statistic were used to select the best-fit models. RESULTS: Body mass index, WC, WHtR, and WHR were comparable discriminators of T2DM among White and Black males, and were superior to ABSI and BAI in predicting T2DM (P < 0.0001). Waist circumference, WHtR, and WHR were the best discriminators among White females, whereas WHR was the best discriminator among Black females. The ABSI was the poorest discriminator of T2DM for all race–gender groups except Black females. Anthropometric values distinguishing T2DM cases from non-cases were lower for Black than White adults. CONCLUSIONS: Anthropometric measures that included WC, either alone or relative to height (WHtR) or hip circumference (WHR), were the strongest discriminators of T2DM across race–gender groups. Body mass index was a comparable discriminator to WC, WHtR, and WHR among males, but not females

    Examining the Role of Environment in a Comprehensive Sample of Compact Groups

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    (Abridged) Compact groups, with their high number densities, small velocity dispersions, and an interstellar medium that has not been fully processed, provide a local analog to conditions of galaxy interactions in the earlier universe. The frequent and prolonged gravitational encounters that occur in compact groups affect the evolution of the constituent galaxies in a myriad of ways, for example gas processing and star formation. Recently, a statistically significant "gap" has been discovered mid-infrared IRAC colorspace of compact group galaxies. This gap is not seen in field samples and is a new example of how the compact group environment may affect the evolution of member galaxies. In order to investigate the origin and nature of this gap, we have compiled a sample of 49 compact groups. We find that a statistically significant deficit of galaxies in this gap region of IRAC colorspace is persistant in this sample, lending support to the hypothesis that the compact group environment inhibits moderate SSFRs. We note a curvature in the colorspace distribution, which is fully consistent with increasing dust temperature as the activity in a galaxy increases. This full sample of 49 compact groups allows us to subdivide the data according to physical properties of the groups. An analysis of these subsamples indicates that neither projected physical diameter nor density show a trend in colorspace within the values represented by this sample. We hypothesize that the apparent lack of a trend is due to the relatively small range of properties in this sample. Thus, the relative influence of stochastic effects becomes dominant. We analyze spectral energy distributions of member galaxies as a function of their location in colorspace and find that galaxies in different regions of MIR colorspace contain dust with varying temperatures and/or PAH emission.Comment: 24 pages, 13 figures. Accepted for publication in The Astronomical Journa

    Congruences modulo prime powers of Hecke eigenvalues in level 11

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    We continue the study of strong, weak, and dcdc-weak eigenforms introduced by Chen, Kiming, and Wiese. We completely determine all systems of Hecke eigenvalues of level 11 modulo 128128, showing there are finitely many. This extends results of Hatada and can be considered as evidence for the more general conjecture formulated by the author together with Kiming and Wiese on finiteness of systems of Hecke eigenvalues modulo prime powers at any fixed level. We also discuss the finiteness of systems of Hecke eigenvalues of level 11 modulo 99, reducing the question to the finiteness of a single eigenvalue. Furthermore, we answer the question of comparing weak and dcdc-weak eigenforms and provide the first known examples of non-weak dcdc-weak eigenforms.Comment: 28 pages; Minor revisio

    Mid-Infrared Evidence for Accelerated Evolution in Compact Group Galaxies

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    We find evidence for accelerated evolution in compact group galaxies from the distribution in mid-infrared colorspace of 42 galaxies from 12 Hickson Compact Groups (HCGs) compared to the the distributions of several other samples including the LVL+SINGS galaxies, interacting galaxies, and galaxies from the Coma Cluster. We find that the HCG galaxies are not uniformly distributed in colorspace, as well as quantitative evidence for a gap. Galaxies in the infall region of the Coma cluster also exhibit a non-uniform distribution and a less well defined gap, which may reflect a similarity with the compact group environment. Neither the Coma Center or interacting samples show evidence of a gap, leading us to speculate that the gap is unique to the environment of high galaxy density where gas has not been fully processed or stripped.Comment: To appear in the Proceedings of the Galaxy Wars: Stellar Populations and Star Formation in Interacting Galaxies Conferenc

    Generation of 3D retinal tissue from human pluripotent stem cells using a directed small molecule-based serum-free microwell platform

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    Retinal degenerative diseases are a leading cause of blindness worldwide with debilitating life-long consequences for the affected individuals. Cell therapy is considered a potential future clinical intervention to restore and preserve sight by replacing lost photoreceptors and/or retinal pigment epithelium. Development of protocols to generate retinal tissue from human pluripotent stem cells (hPSC), reliably and at scale, can provide a platform to generate photoreceptors for cell therapy and to model retinal disease in vitro. Here, we describe an improved differentiation platform to generate retinal organoids from hPSC at scale and free from time-consuming manual microdissection steps. The scale up was achieved using an agarose mould platform enabling generation of uniform self-assembled 3D spheres from dissociated hPSC in microwells. Subsequent retinal differentiation was efficiently achieved via a stepwise differentiation protocol using a number of small molecules. To facilitate clinical translation, xeno-free approaches were developed by substituting Matrigel™ and foetal bovine serum with recombinant laminin and human platelet lysate, respectively. Generated retinal organoids exhibited important features reminiscent of retinal tissue including correct site-specific localisation of proteins involved in phototransduction

    Discordance between the predictors of clinical and imaging remission in patients with early rheumatoid arthritis in clinical practice: implications for the use of ultrasound within a treatment to target strategy

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    Objective: To assess the prevalence, relationship between and predictors of clinical and imaging remission in early rheumatoid arthritis (RA), achieved with treat-to-target management in clinical practice. Methods: A prospective observational study was conducted in patients with new-onset RA. The treatment target was remission by disease activity score (DAS28-CRP<2.6). Twelve month outcomes included DAS28-CRP remission, DAS44-CRP remission, ACR/EULAR Boolean remission (BR) and absent or absent/minimal power Doppler activity (PDA) on ultrasound (US) of 26 joints (total PDA score=0 or ≤1, respectively). Logistic regression was conducted to identify baseline predictors of these outcomes. Results: Of 105 patients with complete 12-month data, the rate of DAS28-CRP remission was 43%, DAS44-CRP remission was 39%, BR was 14%, absent PDA was 40% and absent/minimal PDA was 57%. Amongst patients achieving clinical remission defined by DAS28-CRP, DAS44-CRP or BR, absence of PDA was observed in 42%, 44% and 40%, respectively; absent/minimal PDA was detected in 62%, 66% and 67%, respectively. On multivariable analysis, shorter symptom duration, male gender, fewer tender joints and lower disability were associated with the clinical remission definitions. Lack of osteoarthritis predicted absence of PDA and lower total baseline PDA predicted absent/minimal PDA. Conclusion: DAS28-CRP remission and absence of PDA were observed in almost half of patients, but less than a quarter achieved both. Achievement of BR was rare. The low agreement between any of the clinical and imaging outcomes and differences in their predictors highlight the complex interaction between symptoms and synovitis, with implications for treat-to-target management. Long-term follow-up should determine the most appropriate target
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