7,722 research outputs found
Membrane with internal passages to permit fluid flow and an electrochemical cell containing the same
The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface, an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane for purposes of hydration
Mid-infrared sources in the ELAIS Deep X-ray Survey
We present a crossâcorrelation of the European Large Area Infrared Space Observatory (ISO) survey (ELAIS) with the ELAIS Deep Xâray Survey of the N1 and N2 fields. There are seven Chandra point sources with matches in the ELAIS Final Analysis 15âÎŒm catalogue, out of a total of 28 extragalactic ISO sources present in the Chandra fields. Five of these are consistent with active galactic nuclei (AGN) giving an AGN fraction of âŒ19 per cent in the 15âÎŒm flux range 0.8â6âmJy. We have coâadded the hard Xâray fluxes of the individually undetected ISO sources and find a low significance detection consistent with star formation in the remaining population. We combine our point source crossâcorrelation fraction with the XMMâNewton observations of the Lockman Hole and Chandra observations of the Hubble Deep Field North to constrain source count models of the midâinfrared galaxy population. The low dustâenshrouded AGN fraction in ELAIS implied by the number of crossâidentifications between the ELAIS midâinfrared sample and the Chandra point sources is encouraging for the use of midâinfrared surveys to constrain the cosmic star formation history, provided there are not further large undetected populations of Comptonâthick AGN
The ELAIS Deep X-ray Survey
We present initial follow-up results of the ELAIS Deep X-ray Survey which is
being undertaken with the Chandra and XMM-Newton Observatories. 235 X-ray
sources are detected in our two 75 ks ACIS-I observations in the well-studied
ELAIS N1 and N2 areas. 90% of the X-ray sources are identified optically to
R=26 with a median magnitude of R=24. We show that objects which are unresolved
optically (i.e. quasars) follow a correlation between their optical and X-ray
fluxes, whereas galaxies do not. We also find that the quasars with fainter
optical counterparts have harder X-ray spectra, consistent with absorption at
both wavebands. Initial spectroscopic follow-up has revealed a large fraction
of high-luminosity Type 2 quasars. The prospects for studying the evolution of
the host galaxies of X-ray selected Type 2 AGN are considered.Comment: 9 pages, 5 figures, To appear in Proceedings of XXI Moriond
Conference: "Galaxy Clusters and the High Redshift Universe Observed in
X-rays", edited by D. Neumann, F.Durret, & J. Tran Thanh Va
Membrane with supported internal passages
The invention provides an improved proton exchange membrane for use in electrochemical cells having internal passages parallel to the membrane surface comprising permanent tubes preferably placed at the ends of the fluid passages. The invention also provides an apparatus and process for making the membrane, membrane and electrode assemblies fabricated using the membrane, and the application of the membrane and electrode assemblies to a variety of devices, both electrochemical and otherwise. The passages in the membrane extend from one edge of the membrane to another and allow fluid flow through the membrane and give access directly to the membrane
The ELAIS deep X-ray survey - I. Chandra source catalogue and first results
We present an analysis of two deep (75 ks) Chandra observations of the European Large Area Infrared Space Observatory (ISO) Survey (ELAIS) fields N1 and N2 as the first results from the ELAIS deep X-ray survey. This survey is being conducted in well-studied regions with extensive multiwavelength coverage. Here we present the Chandra source catalogues along with an analysis of source counts, hardness ratios and optical classifications. A total of 233 X-ray point sources are detected in addition to two soft extended sources, which are found to be associated with galaxy clusters. An overdensity of sources is found in N1 with 30 per cent more sources than N2, which we attribute to large-scale structure. A similar variance is seen between other deep Chandra surveys. The source count statistics reveal an increasing fraction of hard sources at fainter fluxes. The number of galaxy-like counterparts also increases dramatically towards fainter fluxes, consistent with the emergence of a large population of obscured sources
Clustering of galaxies at 3.6 microns in the Spitzer Wide-area Infrared Extragalactic legacy survey
We investigate the clustering of galaxies selected in the 3.6 micron band of
the Spitzer Wide-area Infrared Extragalactic (SWIRE) legacy survey. The angular
two-point correlation function is calculated for eleven samples with flux
limits of S_3.6 > 4-400 mujy, over an 8 square degree field. The angular
clustering strength is measured at >5-sigma significance at all flux limits,
with amplitudes of A=(0.49-29)\times10^{-3} at one degree, for a power-law
model, A\theta^{-0.8}. We estimate the redshift distributions of the samples
using phenomological models, simulations and photometric redshifts, and so
derive the spatial correlation lengths. We compare our results with the GalICS
(Galaxies In Cosmological Simulations) models of galaxy evolution and with
parameterized models of clustering evolution. The GalICS simulations are
consistent with our angular correlation functions, but fail to match the
spatial clustering inferred from the phenomological models or the photometric
redshifts. We find that the uncertainties in the redshift distributions of our
samples dominate the statistical errors in our estimates of the spatial
clustering. At low redshifts (median z<0.5) the comoving correlation length is
approximately constant, r_0=6.1\pm0.5h^{-1} Mpc, and then decreases with
increasing redshift to a value of 2.9\pm0.3h^{-1} Mpc for the faintest sample,
for which the median redshift is z=1. We suggest that this trend can be
attributed to a decrease in the average galaxy and halo mass in the fainter
flux-limited samples, corresponding to changes in the relative numbers of
early- and late-type galaxies. However, we cannot rule out strong evolution of
the correlation length over 0.5<z<1.Comment: 14 pages, 9 (colour) figures. Published in MNRA
Herschel Multitiered Extragalactic Survey: clusters of dusty galaxies uncovered by Herschel and Planck
The potential for Planck to detect clusters of dusty, star-forming galaxies at z > 1 is tested by examining the Herschel-SPIRE images of Planck Early Release Compact Source Catalog sources lying in fields observed by the Herschel Multitiered Extragalactic Survey. Of the 16 Planck sources that lie in the âŒ90 sq. deg. examined, we find that 12 are associated with single bright Herschel sources. The remaining four are associated with overdensities of Herschel sources, making them candidate clusters of dusty, star-forming galaxies. We use complementary optical/near-IR data for these âclumpsâ to test this idea, and find evidence for the presence of galaxy clusters in all four cases. We use photometric redshifts and red sequence galaxies to estimate the redshifts of these clusters, finding that they range from 0.8 to 2.3. These redshifts imply that the Herschel sources in these clusters, which contribute to the detected Planck flux, are forming stars very rapidly, with typical total cluster star formation rates >1000M ? yr â1 . The high-redshift clusters discovered in these observations are used to constrain the epoch of cluster galaxy formation, finding that the galaxies in our clusters are 1â1.5 Gyr old at z ⌠1â2. Prospects for the discovery of further clusters of dusty galaxies are discussed, using not only all sky Planck surveys, but also deeper, smaller area, Herschel surveys
Observations of the Hubble Deep Field South with the Infrared Space Observatory - II. Associations and star formation rates
We present results from a deep mid-IR survey of the Hubble Deep Field South
(HDF-S) region performed at 7 and 15um with the CAM instrument on board ISO. We
found reliable optical/near-IR associations for 32 of the 35 sources detected
in this field by Oliver et al. (2002, Paper I): eight of them were identified
as stars, one is definitely an AGN, a second seems likely to be an AGN, too,
while the remaining 22 appear to be normal spiral or starburst galaxies. Using
model spectral energy distributions (SEDs) of similar galaxies, we compare
methods for estimating the star formation rates (SFRs) in these objects,
finding that an estimator based on integrated (3-1000um) IR luminosity
reproduces the model SFRs best. Applying this estimator to model fits to the
SEDs of our 22 spiral and starburst galaxies, we find that they are forming
stars at rates of ~1-100 M_sol/yr, with a median value of ~40M_sol/yr, assuming
an Einstein - de Sitter universe with a Hubble constant of 50 km/s/Mpc, and
star formation taking place according to a Salpeter (1955) IMF across the mass
range 0.1-100M_sol. We split the redshift range 0.0<z<0.6 into two equal-volume
bins to compute raw estimates of the star formation rate density contributed by
these sources, assuming the same cosmology and IMF as above and computing
errors based on estimated uncertainties in the SFRs of individual galaxies. We
compare these results with other estimates of the SFR density made with the
same assumptions, showing them to be consistent with the results of Flores et
al. (1999) from their ISO survey of the CFRS 1415+52 field. However, the
relatively small volume of our survey means that our SFR density estimates
suffer from a large sampling variance, implying that our results, by
themselves, do not place tight constraints on the global mean SFR density.Comment: Accepted for MNRAS. 23 pages, 10 figures (Figs. 4&6 included here as
low resolution JPEGS), latex, uses mn,epsfig. Further information and full
resolution versions of Figs 4&6 available at http://astro.ic.ac.uk/hdfs (v2:
full author list added
Development and clinical performance of high throughput loop-mediated isothermal amplification for detection of malaria.
BACKGROUND: Accurate and efficient detection of sub-microscopic malaria infections is crucial for enabling rapid treatment and interruption of transmission. Commercially available malaria LAMP kits have excellent diagnostic performance, though throughput is limited by the need to prepare samples individually. Here, we evaluate the clinical performance of a newly developed high throughput (HTP) sample processing system for use in conjunction with the Eiken malaria LAMP kit. METHODS: The HTP system utilised dried blood spots (DBS) and liquid whole blood (WB), with parallel sample processing of 94 samples per run. The system was evaluated using 699 samples of known infection status pre-determined by gold standard nested PCR. RESULTS: The sensitivity and specificity of WB-HTP-LAMP was 98.6% (95% CI, 95.7-100), and 99.7% (95% CI, 99.2-100); sensitivity of DBS-HTP-LAMP was 97.1% (95% CI, 93.1-100), and specificity 100% against PCR. At parasite densities greater or equal to 2 parasites/ÎŒL, WB and DBS HTP-LAMP showed 100% sensitivity and specificity against PCR. At densities less than 2 p/ÎŒL, WB-HTP-LAMP sensitivity was 88.9% (95% CI, 77.1-100) and specificity was 99.7% (95% CI, 99.2-100); sensitivity and specificity of DBS-HTP-LAMP was 77.8% (95% CI, 54.3-99.5) and 100% respectively. CONCLUSIONS: The HTP-LAMP system is a highly sensitive diagnostic test, with the potential to allow large scale population screening in malaria elimination campaigns
IRAC Imaging of Lockman Hole
IRAC imaging of a 4'7x4'7 area in the Lockman Hole detected over 400 galaxies
in the IRAC 3.6 micron and 4.5 micron bands, 120 in the 5.8 micron, and 80 in
the 8 micron bandin 30 minutes of observing time. Color-color diagrams suggest
that about half of these galaxies are at redshifts 0.6<z<1.3 with about a
quarter at higher redshifts (z>1.3). We also detect IRAC counterparts for 6 of
the 7 SCUBA sources and all 9 XMM sources in this area. The detection of the
counterparts of the SCUBA sources and galaxies at z>1.3 demonstrates the
ability of IRAC to probe the universe at very high redshifts.Comment: 11 pages, 2 figures. accepted by ApJS, Spizter Special Issu
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