437 research outputs found
An X-ray investigation of the NGC 346 field in the SMC (3): XMM-Newton data
We present new XMM-Newton results on the field around the NGC346 star cluster
in the SMC. This continues and extends previously published work on Chandra
observations of the same field. The two XMM-Newton observations were obtained,
respectively, six months before and six months after the previously published
Chandra data. Of the 51 X-ray sources detected with XMM-Newton, 29 were already
detected with Chandra. Comparing the properties of these X-ray sources in each
of our three datasets has enabled us to investigate their variability on times
scales of a year. Changes in the flux levels and/or spectral properties were
observed for 21 of these sources. In addition, we discovered long-term
variations in the X-ray properties of the peculiar system HD5980, a luminous
blue variable star, that is likely to be a colliding wind binary system, which
displayed the largest luminosity during the first XMM-Newton observation.Comment: 19 pages, 5 figures (in gif), accepted by ApJ, also available from
http://vela.astro.ulg.ac.be/Preprints/P89/index.htm
The Dilemma of Using Sward Height as a Management Tool for Intensively Grazed Sheep Pasture in Spring
Sward height is often used as a tool for both animal and pasture management, especially when continuously grazing pasture. For example, sward height has been used to define the conditions for optimal feed intake of multiple-bearing ewes, both before and after lambing (Everett-Hincks et al.2005; Morris and Kenyon 2004). Sward height is easily applied by the grazier and so becomes an effective tool. However, changes in the leaf distribution and relative species makeup of the sward both seasonally (Thomson et al. 2001) and in response to grazing management (Webby and Pengelly 1986) mean that the amount of pasture per unit height will change. When these changes occur a dilemma is presented to the grazier. How do they manage the trade-off between a simple indicator for management decisions and the lost opportunity of harvesting pasture mass that may be accumulating below the assigned sward height?
This paper presents data from an experiment that investigated the impacts of defoliation strategies on sward of differing starting masses, with defoliation management based on height rather than mass. The paper quantifies the accumulation of herbage below defoliation height and highlights the dilemma of using sward height as a management tool when aiming to maximise the utilisation of our pasture resource
Dark ice in a warming world: advances and challenges in the study of Greenland Ice Sheet's biological darkening
The surface of the Greenland Ice Sheet is darkening, which accelerates its surface melt. The role of glacier ice algae in reducing surface albedo is widely recognised but not well quantified and the feedbacks between the algae and the weathering crust remain poorly understood. In this letter, we summarise recent advances in the study of the biological darkening of the Greenland Ice Sheet and highlight three key research priorities that are required to better understand and forecast algal-driven melt: (i) identifying the controls on glacier ice algal growth and mortality, (ii) quantifying the spatio-temporal variability in glacier ice algal biomass and processes involved in cell redistribution and (iii) determining the albedo feedbacks between algal biomass and weathering crust characteristics. Addressing these key research priorities will allow us to better understand the supraglacial ice-algal system and to develop an integrated model incorporating the algal and physical controls on ice surface albedo
Another intermediate mass black hole in a starburst galaxy?: The luminous X-ray source in NGC 3628 reappears
In a 52 ks-long Chandra ACIS-S observation of the nearby starburst galaxy NGC
3628, obtained to study the starburst-driven outflow from this galaxy, we have
detected a very luminous (L_X = 1.1e40 erg/s in the 0.3-8.0 keV energy band)
point source located at least 20 arcsec (~970 pc) from the nucleus of the
galaxy. No radio, optical or near-IR counterpart to this source has been found.
This is most probably the reappearance of the strongly-variable
X-ray-luminous source discovered by Dahlem et al (1995), which faded by a
factor >27 between December 1991 and March 1994 (at which point it had faded
below the detection limit in a ROSAT HRI observation). This source is clearly a
member of an enigmatic class of X-ray sources that are considerably more
luminous than conventional X-ray binaries but less luminous than AGN, and which
are not found at the dynamical center of the host galaxy.
The Chandra spectrum is best-fit by an absorbed power law model with a photon
index of Gamma = 1.8+/-0.2, similar to that seen in Galactic BH binary
candidates in their hard state. Bremsstrahlung models or multi-color disk
models (the favored spectral model for objects in this class based on ASCA
observations) can provide statistically acceptable fits only if the data at
energies E > 5 keV is ignored. This is one of the first X-ray spectra of such
an object that is unambiguously that of the source alone, free from the
spectral contamination by X-ray emission from the rest of the galaxy that
affects previous spectral studies of these objects using ASCA.Comment: Accepted for publication in the Ap
The BILAG-2004 index is associated with development of new damage in SLE
OBJECTIVE: To determine whether BILAG-2004 index is associated with the development of damage in a cohort of SLE patients. Mortality and development of damage were examined.METHODS: This was a multicentre longitudinal study. Patients were recruited within 12 months of achieving 4th ACR classification criterion for SLE. Data were collected on disease activity, damage, SLE-specific drug exposure, cardiovascular risk factors, antiphospholipid syndrome status and death at every visit. This study ran from 1st January 2005 to 31st December 2017. Descriptive statistics were used to analyse mortality and development of new damage. Poisson regression was used to examine potential explanatory variables for development of new damage.RESULTS: 273 SLE patients were recruited with total follow-up of 1767 patient-years (median 73.4 months). There were 6348 assessments with disease activity scores available for analysis. During follow-up, 13 deaths and 114 new damage items (in 83 patients) occurred. The incidence rate for development of damage was higher in the first 3 years before stabilising at a lower rate. Overall rate for damage accrual was 61.1 per 1000 person-years (95% CI : 50.6, 73.8). Analysis showed that active disease scores according to BILAG-2004 index (systems scores of A or B, counts of systems with A and BILAG-2004 numerical score) were associated with development of new damage. Low disease activity (LDA) states (BILAG-2004 LDA and BILAG Systems Tally (BST) persistent LDA) were inversely associated with development of damage.CONCLUSIONS: BILAG-2004 index is associated with new damage. BILAG-2004 LDA and BST persistent LDA can be considered as treatment targets.</p
Internal and external cooling methods and their effect on body temperature, thermal perception and dexterity
© 2018 The Authors. Published by PLOS. This is an open access article available under a Creative Commons licence.
The published version can be accessed at the following link on the publisher’s website: https://doi.org/10.1371/journal.pone.0191416© 2018 Maley et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Objective The present study aimed to compare a range of cooling methods possibly utilised by occupational workers, focusing on their effect on body temperature, perception and manual dexterity. Methods Ten male participants completed eight trials involving 30 min of seated rest followed by 30 min of cooling or control of no cooling (CON) (34C, 58% relative humidity). The cooling methods utilised were: ice cooling vest (CV0), phase change cooling vest melting at 14C (CV14), evaporative cooling vest (CVEV), arm immersion in 10C water (AI), portable water-perfused suit (WPS), heliox inhalation (HE) and ice slushy ingestion (SL). Immediately before and after cooling, participants were assessed for fine (Purdue pegboard task) and gross (grip and pinch strength) manual dexterity. Rectal and skin temperature, as well as thermal sensation and comfort, were monitored throughout. Results Compared with CON, SL was the only method to reduce rectal temperature (P = 0.012). All externally applied cooling methods reduced skin temperature (P0.05). Conclusion The present study observed that ice ingestion or ice applied to the skin produced the greatest effect on rectal and skin temperature, respectively. AI should not be utilised if workers require subsequent fine manual dexterity. These results will help inform future studies investigating appropriate pre-cooling methods for the occupational worker.This project is financially supported by the US Government through the Technical Support Working Group within the Combating Terrorism Technical Support Office.Published versio
Functional distinctiveness of major plant lineages
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106060/1/jec12208.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/106060/2/jec12208-sup-0001-Supp_Info.pd
The SCUBA HAlf Degree Extragalactic Survey – III. Identification of radio and mid-infrared counterparts to submillimetre galaxies
Determining an accurate position for a submillimetre (submm) galaxy (SMG) is the crucial step that enables us to move from the basic properties of an SMG sample – source counts and 2D clustering – to an assessment of their detailed, multiwavelength properties, their contribution to the history of cosmic star formation and their links with present-day galaxy populations. In this paper, we identify robust radio and/or infrared (IR) counterparts, and hence accurate positions, for over two-thirds of the SCUBA HAlf-Degree Extragalactic Survey (SHADES) Source Catalogue, presenting optical, 24-μm and radio images of each SMG. Observed trends in identification rate have given no strong rationale for pruning the sample. Uncertainties in submm position are found to be consistent with theoretical expectations, with no evidence for significant additional sources of error. Employing the submm/radio redshift indicator, via a parametrization appropriate for radio-identified SMGs with spectroscopic redshifts, yields a median redshift of 2.8 for the radio-identified subset of SHADES, somewhat higher than the median spectroscopic redshift. We present a diagnostic colour–colour plot, exploiting Spitzer photometry, in which we identify regions commensurate with SMGs at very high redshift. Finally, we find that significantly more SMGs have multiple robust counterparts than would be expected by chance, indicative of physical associations. These multiple systems are most common amongst the brightest SMGs and are typically separated by 2–6 arcsec, ~15–50/ sin i kpc at z∼ 2, consistent with early bursts seen in merger simulations
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