18,654 research outputs found

    A systematic search for massive young stars in the Galaxy - the RMS survey

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    We have selected red MSX sources (RMS) that have the colours of massive young stellar objects (MYSOs). Our aim is to generate a large, systematically selected sample to address questions such as their luminosity function, lifetimes, clustering and triggering. Other objects such as UCHIIs, PN, PPN and AGB stars have similar IR colours and a large programme of ground-based follow-up observations is underway to identify and eliminate these from the sample of the red MSX sources. These include radio continuum observations, kinematic distances, ground-based mid-IR imaging, near-IR imaging and spectroscopy to distinguish. We report the progress of these campaigns on the 3000 candidates, with initial indications showing that a substantial fraction are indeed massive YSOs.Comment: 3 pages, 4 figures Talk in conference: Milky Way surveys, the structure and evolution of our Galaxy, Boston 200

    Pseudospectral methods for atoms in strong magnetic fields

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    We present a new pseudospectral algorithm for the calculation of the structure of atoms in strong magnetic fields. We have verified this technique for one, two and three-electron atoms in zero magnetic fields against laboratory results and find typically better than one-percent accuracy. We further verify this technique against the state-of-the-art calculations of hydrogen, helium and lithium in strong magnetic fields (up to about 2×1062\times 10^{6} T) and find a similar level of agreement. The key enabling advantages of the algorithm are its simplicity (about 130 lines of commented code) and its speed (about 10210510^2-10^5 times faster than finite-element methods to achieve similar accuracy).Comment: 10 pages, version accepted to MNRA

    Monitoring Methods for Enhanced Aquifer Recharge Projects

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    This paper presents an overview of enhanced aquifer recharge, its current status in New Mexico, and methods that can be used to monitor the movement and quality of recharged water. Despite their growing use in communities throughout the United States and particularly in the arid Western United States, no enhanced aquifer recharge projects have yet been implemented in New Mexico, although several entities are exploring the feasibility of such projects. Concerns about potential impacts to water quality and the potential for disputes over water accounting have been raised by regulatory agencies. Permitting systems for aquifer recharge projects are being established by the New Mexico Office of the State Engineer and the New Mexico Environment Department Ground Water Quality Bureau, but have yet to be implemented. Comprehensive and effective monitoring programs will likely be required for large aquifer recharge projects in New Mexico. Monitoring programs are typically designed to track recharged water along its entire flow path to ensure that it reaches its intended storage location, that it does not adversely affect the quality of existing groundwater or soils, and to determine the amount of recoverable water. For a surface infiltration project, the monitoring program is often more complex than for a direct injection system because instrumentation must be installed within the vadose zone as well as the saturated zone. A variety of methods are available to monitor the movement of water and water quality changes within the vadose zone; the most appropriate method depends on the hydrogeologic characteristics of a given site. Common techniques include neutron logging, using heat as a tracer, tensiometers, porous cup lysimeters, and ground surface imagery techniques

    Determining the WIMP mass using the complementarity between direct and indirect searches and the ILC

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    We study the possibility of identifying dark matter properties from XENON-like 100 kg experiments and the GLAST satellite mission. We show that whereas direct detection experiments will probe efficiently light WIMPs, given a positive detection (at the 10% level for mχ50m_{\chi} \lesssim 50 GeV), GLAST will be able to confirm and even increase the precision in the case of a NFW profile, for a WIMP-nucleon cross-section σχp108\sigma_{\chi-p} \lesssim 10^{-8} pb. We also predict the rate of production of a WIMP in the next generation of colliders (ILC), and compare their sensitivity to the WIMP mass with the XENON and GLAST projects.Comment: 32 pages, new figures and a more detailed statistical analysis. Final version to appear in JCA

    Tubulin cofactors and Arl2 are cage-like chaperones that regulate the soluble αβ-tubulin pool for microtubule dynamics.

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    Microtubule dynamics and polarity stem from the polymerization of αβ-tubulin heterodimers. Five conserved tubulin cofactors/chaperones and the Arl2 GTPase regulate α- and β-tubulin assembly into heterodimers and maintain the soluble tubulin pool in the cytoplasm, but their physical mechanisms are unknown. Here, we reconstitute a core tubulin chaperone consisting of tubulin cofactors TBCD, TBCE, and Arl2, and reveal a cage-like structure for regulating αβ-tubulin. Biochemical assays and electron microscopy structures of multiple intermediates show the sequential binding of αβ-tubulin dimer followed by tubulin cofactor TBCC onto this chaperone, forming a ternary complex in which Arl2 GTP hydrolysis is activated to alter αβ-tubulin conformation. A GTP-state locked Arl2 mutant inhibits ternary complex dissociation in vitro and causes severe defects in microtubule dynamics in vivo. Our studies suggest a revised paradigm for tubulin cofactors and Arl2 functions as a catalytic chaperone that regulates soluble αβ-tubulin assembly and maintenance to support microtubule dynamics

    Histological Examination in Obtaining a Diagnosis in Patients with Lymphadenopathy in Lima, Peru.

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    The differential diagnosis for lymphadenopathy is wide and clinical presentations overlap, making obtaining an accurate diagnosis challenging. We sought to characterize the clinical and radiological characteristics, histological findings, and diagnoses for a cohort of patients with lymphadenopathy of unknown etiology. 121 Peruvian adults with lymphadenopathy underwent lymph node biopsy for microbiological and histopathological evaluation. Mean patient age was 41 years (Interquartile Range 26-52), 56% were males, and 39% were HIV positive. Patients reported fever (31%), weight loss (23%), and headache (22%); HIV infection was associated with fever (P < 0.05) and gastrointestinal symptoms (P < 0.05). Abnormalities were reported in 40% of chest X-rays (N = 101). Physicians suspected TB in 92 patients (76%), lymphoma in 19 patients (16%), and other malignancy in seven patients (5.8%). Histological diagnoses (N = 117) included tuberculosis (34%), hyperplasia (27%), lymphoma (13%), and nonlymphoma malignancy (14%). Hyperplasia was more common (P < 0.001) and lymphoma less common (P = 0.005) among HIV-positive than HIV-negative patients. There was a trend toward reduced frequency of caseous necrosis in samples from HIV-positive than HIV-negative TB patients (67 versus 93%, P = 0.055). The spectrum of diagnoses was broad, and clinical and radiological features correlated poorly with diagnosis. On the basis of clinical features, physicians over-diagnosed TB, and under-diagnosed malignancy. Although this may not be inappropriate in resource-limited settings where TB is the most frequent easily treatable cause of lymphadenopathy, diagnostic delays can be detrimental to patients with malignancy. It is important that patients with lymphadenopathy undergo a full diagnostic work-up including sampling for histological evaluation to obtain an accurate diagnosis

    Was I There? Impact of Platform and Headphones on 360 Video Immersion

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    Virtual reality industries claim that 360 videos are a powerful tool for creating empathy because they are an immersive medium, and wearing headphones is encouraged for the full immersive experience. To investigate these claims, we carried out a 2x2 between subjects lab study (n=40) to explore whether 360 viewing platform (magic window / google cardboard) and headphone use (with / without) have an effect on Film-Immersion for the 360 video Fire Rescue. Our results reveal a significant interaction effect: headphones increased immersion for google cardboard, but decreased immersion for magic window. However, not all dimensions of the immersive experience were affected. This suggests that head-mounted displays increase presence, but do not necessarily lead to more empathy and greater interest in the 360 video. Thematic analysis of interview data suggests contributing factors such as fear of missing out (FOMO). These findings have implications for film makers and researchers of 360 videos

    Fine particulate matter pollution and risk of community-acquired sepsis

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    While air pollution has been associated with health complications, its effect on sepsis risk is unknown. We examined the association between fine particulate matter (PM2.5) air pollution and risk of sepsis hospitalization. We analyzed data from the 30,239 community-dwelling adults in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) cohort linked with satellite-derived measures of PM2.5 data. We defined sepsis as a hospital admission for a serious infection with &ge;2 systemic inflammatory response (SIRS) criteria. We performed incidence density sampling to match sepsis cases with 4 controls by age (&plusmn;5 years), sex, and race. For each matched group we calculated mean daily PM2.5 exposures for short-term (30-day) and long-term (one-year) periods preceding the sepsis event. We used conditional logistic regression to evaluate the association between PM2.5 exposure and sepsis, adjusting for education, income, region, temperature, urbanicity, tobacco and alcohol use, and medical conditions. We matched 1386 sepsis cases with 5544 non-sepsis controls. Mean 30-day PM2.5 exposure levels (Cases 12.44 vs. Controls 12.34 &micro;g/m3; p = 0.28) and mean one-year PM2.5 exposure levels (Cases 12.53 vs. Controls 12.50 &micro;g/m3; p = 0.66) were similar between cases and controls. In adjusted models, there were no associations between 30-day PM2.5 exposure levels and sepsis (4th vs. 1st quartiles OR: 1.06, 95% CI: 0.85&ndash;1.32). Similarly, there were no associations between one-year PM2.5 exposure levels and sepsis risk (4th vs. 1st quartiles OR: 0.96, 95% CI: 0.78&ndash;1.18). In the REGARDS cohort, PM2.5 air pollution exposure was not associated with risk of sepsis
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