1,714 research outputs found
Direct spectroscopic studies of cation translocation by Torpedo acetylcholine receptor on a time scale of physiological relevance.
A detection pipeline for galactic binaries in LISA data
The Galaxy is suspected to contain hundreds of millions of binary white dwarf
systems, a large fraction of which will have sufficiently small orbital period
to emit gravitational radiation in band for space-based gravitational wave
detectors such as the Laser Interferometer Space Antenna (LISA). LISA's main
science goal is the detection of cosmological events (supermassive black hole
mergers, etc.) however the gravitational signal from the galaxy will be the
dominant contribution to the data -- including instrumental noise -- over
approximately two decades in frequency. The catalogue of detectable binary
systems will serve as an unparalleled means of studying the Galaxy.
Furthermore, to maximize the scientific return from the mission, the data must
be "cleansed" of the galactic foreground. We will present an algorithm that can
accurately resolve and subtract >10000 of these sources from simulated data
supplied by the Mock LISA Data Challenge Task Force. Using the time evolution
of the gravitational wave frequency, we will reconstruct the position of the
recovered binaries and show how LISA will sample the entire compact binary
population in the Galaxy.Comment: 12 pages, 8 figure
Time-and-motion tool for the assessment of working time in tuberculosis laboratories: a multicentre study
SETTING: Implementation of novel diagnostic assays in tuberculosis (TB) laboratory diagnosis requires effective management of time and resources. OBJECTIVE: To further develop and assess at multiple centres a time-and-motion (T&M) tool as an objective means for recording the actual time spent on running laboratory assays. DESIGN: Multicentre prospective study conducted in six European Union (EU) reference TB laboratories. RESULTS: A total of 1060 specimens were tested using four laboratory assays. The number of specimens per batch varied from one to 60; a total of 64 recordings were performed. Theoretical hands-on times per specimen (TTPS) in h:min:s for Xpert® MTB/RIF, mycobacterial interspersed repetitive unit-variable number of tandem repeats genotyping, Ziehl-Neelsen staining and manual fluorescence microscopy were respectively 00:33:02 ± 00:12:32, 00:13:34 ± 00:03:11, 00:09:54 ± 00:00:53 and 00:06:23 ± 00:01:36. Variations between laboratories were predominantly linked to the time spent on reporting and administrative procedures. Processing specimens in batches could help save time in highly automated assays (e.g., line-probe) (TTPS 00:14:00 vs. 00:09:45 for batches comprising 7 and 31 specimens, respectively). CONCLUSIONS: The T&M tool can be considered a universal and objective methodology contributing to workload assessment in TB diagnostic laboratories. Comparison of workload between laboratories could help laboratory managers justify their resource and personnel needs for the implementation of novel, time-saving, cost-effective technologies, as well as identify areas for improvement
Early Universe Constraints on Time Variation of Fundamental Constants
We study the time variation of fundamental constants in the early Universe.
Using data from primordial light nuclei abundances, CMB and the 2dFGRS power
spectrum, we put constraints on the time variation of the fine structure
constant , and the Higgs vacuum expectation value leads to a variation
in the electron mass, among other effects. Along the same line, we study the
variation of and the electron mass . In a purely phenomenological
fashion, we derive a relationship between both variations.Comment: 18 pages, 12 figures, accepted for publication in Physical Review
The SWAP EUV Imaging Telescope Part I: Instrument Overview and Pre-Flight Testing
The Sun Watcher with Active Pixels and Image Processing (SWAP) is an EUV
solar telescope on board ESA's Project for Onboard Autonomy 2 (PROBA2) mission
launched on 2 November 2009. SWAP has a spectral bandpass centered on 17.4 nm
and provides images of the low solar corona over a 54x54 arcmin field-of-view
with 3.2 arcsec pixels and an imaging cadence of about two minutes. SWAP is
designed to monitor all space-weather-relevant events and features in the low
solar corona. Given the limited resources of the PROBA2 microsatellite, the
SWAP telescope is designed with various innovative technologies, including an
off-axis optical design and a CMOS-APS detector. This article provides
reference documentation for users of the SWAP image data.Comment: 26 pages, 9 figures, 1 movi
Point-of-care screening for a current Hepatitis C virus infection: influence on uptake of a concomitant offer of HIV screening
Eliminating hepatitis C as a public health threat requires an improved understanding of how to increase testing uptake. We piloted point-of-care testing (POCT) for a current HCV infection in an inner-city Emergency Department (ED) and assessed the influence on uptake of offering concomitant screening for HIV. Over four months, all adults attending ED with minor injuries were first invited to complete an anonymous questionnaire then invited to test in alternating cycles offering HCV POCT or HCV+HIV POCT. Viral RNA was detected in finger-prick blood by GeneXpert. 814/859 (94.8%) questionnaires were returned and 324/814 (39.8%) tests were accepted, comprising 211 HCV tests and 113 HCV+HIV tests. Offering concomitant HIV screening reduced uptake after adjusting for age and previous HCV testing (odds ratio 0.51; 95% confidence interval [CI] 0.38–0.68; p < 0.001). HCV prevalence was 1/324 (0.31%; 95% CI 0.05–1.73); no participant tested positive for HIV. 167/297 (56.2%) POCT participants lived in the most deprived neighbourhoods in England. HCV RNA testing using finger-prick blood was technically feasible. Uptake was moderate and the offer of concomitant HIV screening showed a detrimental impact on acceptability in this low prevalence population. The findings should be confirmed in a variety of other community settings
Investigating the driving mechanisms of coronal mass ejections
The objective of this investigation was to first examine the kinematics of
coronal mass ejections (CMEs) using EUV and coronagraph images, and then to
make a comparison with theoretical models in the hope to identify the driving
mechanisms of the CMEs. We have studied two CMEs which occurred on 2006 Dec. 17
(CME06) and 2007 Dec. 31 (CME07). The models studied in this work were
catastrophe, breakout, and toroidal instability models. We found that after the
eruption, the accelerations of both events exhibited a drop before increasing
again. Our comparisons with the theories suggested that CME06 can be best
described by a hybrid of the catastrophe and breakout models while CME07 is
most consistent with the breakout model.Comment: 9 pages 7 figure
Comparative analyses of Campylobacter concisusstrains reveal the genome of the reference strain BAA-1457 is not representative of the species
<p>Abstract</p> <p>Background</p> <p>Several studies have shown that significant genotypic heterogeneity exists among <it>Campylobacter concisus </it>strains. Recently, the genome of <it>C. concisus </it>UNSWCD, isolated from a patient with Crohn's disease, was sequenced.</p> <p>Results</p> <p>In this study, comparative analyses were performed between strain UNSWCD and BAA-1457, isolated from a patient with acute gastroenteritis. Searches between <it>C. concisus </it>UNSWCD and BAA-1457 showed that 76% of genes were homologues, whereas those between <it>C. jejuni </it>strains showed 90-91% to be homologues, indicating substantial variation exists within these two <it>C. concisus </it>genomes. More specific bidirectional homology searches identified 1593 genes that are shared between these strains, and 115 and 281 genes unique to UNSWCD and BAA-1457, respectively. Significantly, differences in the type of flagellin glycosylation pathways between the two strains were identified and confirmed by PCR. The protein profiles of UNSWCD, BAA-1457 and a further six strains of <it>C. concisus </it>were compared and analyzed bioinformatically, and this differentiated the strains into four clades. BAA-1457 was found to be highly divergent (average similarity: 56.8%) from the other seven strains (mean average similarity ± standard deviation: 64.7 ± 1.7%). Furthermore, searches for homologues of the 1593 proteins found to be common between UNSWCD and BAA-1457 were conducted against all available bacterial genomes, and 18 proteins were found to be unique to <it>C. concisus</it>, of which 6 were predicted to be secreted, and may represent good markers for detection of this species.</p> <p>Conclusions</p> <p>This study has elucidated several features that may be responsible for the heterogeneity that exists among <it>C. concisus </it>strains, and has determined that the strain BAA-1457 is genetically atypical to other <it>C. concisus </it>strains and is not a good candidate reference strain.</p
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