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Deriving glacier outlines from satellite data has become increasingly popular in the past decade. In particular when glacier outlines are used as a base for change assessment, it is important to know how accurate they are. Calculating the accuracy correctly is challenging, as appropriate reference data (e.g. from higher-resolution sensors) are seldom available. Moreover, after the required manual correction of the raw outlines (e.g. for debris cover), such a comparison would only reveal the accuracy of the analyst rather than of the algorithm applied. Here we compare outlines for clean and debris-covered glaciers, as derived from single and multiple digitizing by different or the same analysts on very high- (1 m) and medium-resolution (30 m) remote-sensing data, against each other and to glacier outlines derived from automated classification of Landsat Thematic Mapper data. Results show a high variability in the interpretation of debris-covered glacier parts, largely independent of the spatial resolution (area differences were up to 30%), and an overall good agreement for clean ice with sufficient contrast to the surrounding terrain (differences ∼5%). The differences of the automatically derived outlines from a reference value are as small as the standard deviation of the manual digitizations from several analysts. Based on these results, we conclude that automated mapping of clean ice is preferable to manual digitization and recommend using the latter method only for required corrections of incorrectly mapped glacier parts (e.g. debris cover, shadow).
A few studies have examined the association between vitamin D and telomere length, and fewer still have examined the relationship in black or male populations. We investigated the cross-sectional association between the vitamin D metabolite 25-hydroxyvitamin D (25(OH)D) concentration in plasma and relative leucocyte telomere length (LTL) in 1154 US radiologic technologists who were 48–93 years old (373 white females, 278 white males, 338 black females, 165 black males). Plasma 25(OH)D concentration was measured by the chemiluminescence immunoassay, and relative LTL was measured by quantitative PCR. Logistic regression was used to obtain OR and 95 % CI for long v. short (based on median) LTL in relation to continuous 25(OH)D, quartiles of 25(OH)D and 25(OH)D deficiency. We found no significant association between continuous 25(OH)D and long LTL in all participants (Ptrend=0·440), nor in white females (Ptrend=0·845), white males (Ptrend=0·636), black females (Ptrend=0·967) or black males (Ptrend=0·484). Vitamin D deficiency (defined as 25(OH)D<30 nmol/l), however, was significantly associated with short LTL in whites (P=0·024), but not in other groups. In this population, we found little evidence to support associations between 25(OH)D and long LTL over the entire range of 25(OH)D in the overall study population or by sex and race.
To observe patient care across hemodialysis facilities enrolled in the National Opportunity to Improve Infection Control in ESRD (end-stage renal disease) (NOTICE) project in order to evaluate adherence to evidence-based practices aimed at prevention of infection.
SETTING AND PARTICIPANTS
Thirty-four hemodialysis facilities were randomly selected from among 772 facilities in 4 end-stage renal disease participating networks. Facility selection was stratified on dialysis organization affiliation, size, socioeconomic status, and urban/rural status.
Trained infection control evaluators used an infection control worksheet to observe 73 distinct infection control practices at the hemodialysis facilities, from October 1, 2011, through January 31, 2012.
There was considerable variation in infection control practices across enrolled facilities. Overall adherence to recommended practices was 68% (range, 45%–92%) across all facilities. Overall adherence to expected hand hygiene practice was 72% (range, 10%–100%). Compliance to hand hygiene before and after procedures was high; however, during procedures hand hygiene compliance averaged 58%. Use of chlorhexidine as the specific agent for exit site care was 19% overall but varied from 0% to 35% by facility type. The 8 checklists varied in the frequency of perfect performance from 0% for meeting every item on the checklist for disinfection practices to 22% on the arteriovenous access practices at initiation.
Our findings suggest that there are many areas for improvement in hand hygiene and other infection prevention practices in end-stage renal disease. These NOTICE project findings will help inform the development of a larger quality improvement initiative at dialysis facilities.
In August 2011, one of the earliest cases of influenza A(H3N2) variant [A(H3N2)v] virus infection was hospitalized with severe illness. To investigate the potential for healthcare-associated transmission of influenza A(H3N2)v, we evaluated both healthcare providers and patient contacts of the case. We found that healthcare-associated transmission was unlikely.
Pulsating pre-main-sequence (PMS) stars afford the earliest opportunity in the lifetime of a star to which the concepts of asteroseismology can be applied. PMS stars should be structurally simpler than their evolved counterparts, thus (hopefully!) making any asteroseismic analysis relatively easier. Unfortunately, this isn't necessarily the case. The majority of these stars (around 80) are δ Scuti pulsators, with a couple of γ Doradus, γ Doradus – δ Scuti hybrids, and slowly pulsating B stars thrown into the mix. The majority of these stars have only been discovered within the last ten years, with the community still uncovering the richness of phenomena associated with these stars, many of which defy traditional asteroseismic analysis.
A systematic asteroseismic analysis of all of the δ Scuti PMS stars was performed in order to get a better handle on the properties of these stars as a group. Some strange results have been found, including one star pulsating up to the theoretical acoustic cut-off frequency of the star, and a number of stars in which the most basic asteroseismic analysis suggests problems with the stars' positions in the Hertzsprung-Russell diagram. From this we get an idea of the\break constraints — or lack thereof — that these results can put on PMS stellar evolution.
The Australian Square Kilometre Array Pathfinder (ASKAP) will give us an unprecedented opportunity to investigate the transient sky at radio wavelengths. In this paper we present VAST, an ASKAP survey for Variables and Slow Transients. VAST will exploit the wide-field survey capabilities of ASKAP to enable the discovery and investigation of variable and transient phenomena from the local to the cosmological, including flare stars, intermittent pulsars, X-ray binaries, magnetars, extreme scattering events, interstellar scintillation, radio supernovae, and orphan afterglows of gamma-ray bursts. In addition, it will allow us to probe unexplored regions of parameter space where new classes of transient sources may be detected. In this paper we review the known radio transient and variable populations and the current results from blind radio surveys. We outline a comprehensive program based on a multi-tiered survey strategy to characterise the radio transient sky through detection and monitoring of transient and variable sources on the ASKAP imaging timescales of 5 s and greater. We also present an analysis of the expected source populations that we will be able to detect with VAST.
The microstructure and microchemistry of a number of melt textured CuInSe2 ingots prepared from a variety of starting charge compositions have been investigated using a combination of TEM, EPMA and Auger spectroscopy. If a stoichiometric starting mixture is used, In-rich and Cu-rich precipitates are found at the first and last to freeze zones of the ingot respectively, accompanied by an intervening mid-portion of inclusion free (although slightly off-stoichiometry) CuInSe2 We have found that in order to achieve an optimum matrix composition, a Cu-rich charge is required; however, this leads to a fine distribution of copper selenide particles throughout the ingot. If the starting charge is In-rich, then the boule contains In-rich precipitates and the matrix composition is In-rich and Cu-deficient. These observations are correlated with the observed electrical characteristics of the boules.