1,082 research outputs found
Genetic characterization of Yersinia enterocolitica collected from tonsils of slaughtered pigs
From January to March 2009, detection of pathogenic Yersinia enterocolitica was done from 900 tonsils swabs collected from 45 pig batches in one slaughterhouse. 316 Y. enterocolitica isolates were collected and confirmed as pathogenic biotype by biochemical tests. For this study, these strains were genetically characterized on the basis of their virulence genes and their PFGE profiles. Real Time PCR was used to evaluate the presence of genes ail, myfA, and ystA on the genome and the gene yadA on the pYV plasmid. PFGE analysis using XbaI enzyme was also realised
Yersinia enterocolitica prevalence, on fresh pork, poultry and beef meat at retail level, in France
Y. enterocolitica is a zoonotic agent, and the third bacterial cause of human entiritis in Europe. The objective of this study was to assess consumer exposure to the pathogen Y. enterocolitica through meat consumption over a one-year period, in France. In this context, the prevalence of Y. enterocolitica was established on samples of fresh pork, beef and poultry collected at retail level in France. Of the 649 samples, 5.1% (34) were positive for Y. enterocolitica. No significant difference in prevalence between the categories of fresh meat was observed: the prevalence was 5.2 % for pork, 5.2% for beef and 5.9% for poultry meat. However, tongues of pork were highly contaminated by Y. enterocolitica (12.5%) compared to other type of meat
Ultradeep Infrared Array Camera Observations of sub-L* z~7 and z~8 Galaxies in the Hubble Ultra Deep Field: the Contribution of Low-Luminosity Galaxies to the Stellar Mass Density and Reionization
We study the Spitzer Infrared Array Camera (IRAC) mid-infrared (rest-frame
optical) fluxes of 14 newly WFC3/IR-detected z=7 z_{850}-dropout galaxies and 5
z=8 Y_{105}-dropout galaxies. The WFC3/IR depth and spatial resolution allow
accurate removal of contaminating foreground light, enabling reliable flux
measurements at 3.6 micron and 4.5 micron. None of the galaxies are detected to
[3.6]=26.9 (AB, 2 sigma), but a stacking analysis reveals a robust detection
for the z_{850}-dropouts and an upper limit for the Y_{105}-dropouts. We
construct average broadband SEDs using the stacked ACS, WFC3, and IRAC fluxes
and fit stellar population synthesis models to derive mean redshifts, stellar
masses, and ages. For the z_{850}-dropouts, we find z=6.9^{+0.1}_{-0.1},
(U-V)_{rest}=0.4, reddening A_V=0, stellar mass M*=1.2^{+0.3}_{-0.6} x 10^9
M_sun (Salpeter IMF). The best-fit ages ~300Myr, M/L_V=0.2, and
SSFR=1.7Gyr^{-1} are similar to values reported for luminous z=7 galaxies,
indicating the galaxies are smaller but not younger. The sub-L* galaxies
observed here contribute significantly to the stellar mass density and under
favorable conditions may have provided enough photons for sustained
reionization at 7<z<11. In contrast, the z=8.3^{+0.1}_{-0.2} Y_{105}-dropouts
have stellar masses that are uncertain by 1.5 dex due to the near-complete
reliance on far-UV data. Adopting the 2 sigma upper limit on the M/L(z=8), the
stellar mass density to M_{UV,AB} < -18 declines from
rho*(z=7)=3.7^{+1.0}_{-1.8} x 10^6 M_sun Mpc^{-3} to rho*(z=8) < 8 x 10^5 M_sun
Mpc^{-3}, following (1+z)^{-6} over 3<z<8. Lower masses at z=8 would signify
more dramatic evolution, which can be established with deeper IRAC
observations, long before the arrival of the James Webb Space Telescope.Comment: 6 pages, 3 figures, 2 tables, emulateapj, accepted for publication in
ApJ
Beam tests of the gas electron multiplier
We describe the results of systematic measurements, carried out with single and double GEM detectors with printed circuit read-out and having an active area 10x10 cm , both in the laboratory and in a high energy charged particles beam at CERN. Using fast analogue readout electronics, we demonstrate efficiencies for minimum ionizing particles close to 100%, with typical signal/noise ratios above 50 and up to 10 for the single and double GEM configuration, respectively, and a time resolution of 15 ns fwhm. Localization accuracies around 40 mm rms have been obtained for perpendicular tracks, degrading to 200 mm at 20° of incidence to the normal. Operated in a non-flammable gas mixture (argon-carbon dioxide), GEM detectors are robust, light and cheap to manufacture, and offer excellent performances and reliability suited for use in the harsh environments met at high luminosity colliders
On Words with the Zero Palindromic Defect
We study the set of finite words with zero palindromic defect, i.e., words
rich in palindromes. This set is factorial, but not recurrent. We focus on
description of pairs of rich words which cannot occur simultaneously as factors
of a longer rich word
Expanded Search for z~10 Galaxies from HUDF09, ERS, and CANDELS Data: Evidence for Accelerated Evolution at z>8?
We search for z~10 galaxies over ~160 arcmin^2 of WFC3/IR data in the Chandra
Deep Field South, using the public HUDF09, ERS, and CANDELS surveys, that reach
to 5sigma depths ranging from 26.9 to 29.4 in H_160 AB mag. z>~9.5 galaxy
candidates are identified via J_125-H_160>1.2 colors and non-detections in any
band blueward of J_125. Spitzer IRAC photometry is key for separating the
genuine high-z candidates from intermediate redshift (z~2-4) galaxies with
evolved or heavily dust obscured stellar populations. After removing 16 sources
of intermediate brightness (H_160~24-26 mag) with strong IRAC detections, we
only find one plausible z~10 galaxy candidate in the whole data set, previously
reported in Bouwens et al. (2011). The newer data cover a 3x larger area and
provide much stronger constraints on the evolution of the UV luminosity
function (LF). If the evolution of the z~4-8 LFs is extrapolated to z~10, six
z~10 galaxies are expected in our data. The detection of only one source
suggests that the UV LF evolves at an accelerated rate before z~8. The
luminosity density is found to increase by more than an order of magnitude in
only 170 Myr from z~10 to z~8. This increase is >=4x larger than expected from
the lower redshift extrapolation of the UV LF. We are thus likely witnessing
the first rapid build-up of galaxies in the heart of cosmic reionization.
Future deep HST WFC3/IR data, reaching to well beyond 29 mag, can enable a more
robust quantification of the accelerated evolution around z~10.Comment: 13 pages, 11 figures, ApJ resubmitted after referee repor
Relevance of soft modes for order parameter fluctuations in the Two-Dimensional XY model
We analyse the spin wave approximation for the 2D-XY model, directly in
reciprocal space. In this limit the model is diagonal and the normal modes are
statistically independent. Despite this simplicity non-trivial critical
properties are observed and exploited. We confirm that the observed asymmetry
for the probability density function for order parameter fluctuations comes
from the divergence of the mode amplitudes across the Brillouin zone. We show
that the asymmetry is a many body effect despite the importance played by the
zone centre. The precise form of the function is dependent on the details of
the Gibbs measure, giving weight to the idea that an effective Gibbs measure
should exist in non-equilibrium systems, if a similar distribution is observed.Comment: 12 pages, 9 figure
Shopping malls as an environment for rehabilitation: Evaluations and interventions for persons with a disability
UV Luminosity Functions from 132 z~7 and z~8 Lyman-Break Galaxies in the ultra-deep HUDF09 and wide-area ERS WFC3/IR Observations
We identify 73 z~7 and 59 z~8 candidate galaxies in the reionization epoch,
and use this large 26-29.4 AB mag sample of galaxies to derive very deep
luminosity functions to <-18 AB mag and the star formation rate density at z~7
and z~8. The galaxy sample is derived using a sophisticated Lyman-Break
technique on the full two-year WFC3/IR and ACS data available over the HUDF09
(~29.4 AB mag, 5 sigma), two nearby HUDF09 fields (~29 AB mag, 14 arcmin) and
the wider area ERS (~27.5 AB mag) ~40 arcmin**2). The application of strict
optical non-detection criteria ensures the contamination fraction is kept low
(just ~7% in the HUDF). This very low value includes a full assessment of the
contamination from lower redshift sources, photometric scatter, AGN, spurious
sources, low mass stars, and transients (e.g., SNe). From careful modelling of
the selection volumes for each of our search fields we derive luminosity
functions for galaxies at z~7 and z~8 to <-18 AB mag. The faint-end slopes
alpha at z~7 and z~8 are uncertain but very steep at alpha = -2.01+/-0.21 and
alpha=-1.91+/-0.32, respectively. Such steep slopes contrast to the local
alpha<~-1.4 and may even be steeper than that at z~4 where alpha=-1.73+/-0.05.
With such steep slopes (alpha<~-1.7) lower luminosity galaxies dominate the
galaxy luminosity density during the epoch of reionization. The star formation
rate densities derived from these new z~7 and z~8 luminosity functions are
consistent with the trends found at later times (lower redshifts). We find
reasonable consistency, with the SFR densities implied from reported stellar
mass densities, being only ~40% higher at z<7. This suggests that (1) the
stellar mass densities inferred from the Spitzer IRAC photometry are reasonably
accurate and (2) that the IMF at very high redshift may not be very different
from that at later times.Comment: 38 pages, 21 figures, 20 tables, ApJ, accepted for publicatio
ESO Imaging Survey: infrared observations of CDF-S and HDF-S
This paper presents infrared data obtained from observations carried out at
the ESO 3.5m New Technology Telescope (NTT) of the Hubble Deep Field South
(HDF-S) and the Chandra Deep Field South (CDF-S). These data were taken as part
of the ESO Imaging Survey (EIS) program, a public survey conducted by ESO to
promote follow-up observations with the VLT. In the HDF-S field the infrared
observations cover an area of ~53 square arcmin, encompassing the HST WFPC2 and
STIS fields, in the JHKs passbands. The seeing measured in the final stacked
images ranges from 0.79" to 1.22" and the median limiting magnitudes (AB
system, 2" aperture, 5sigma detection limit) are J_AB~23.0, H_AB~22.8 and
K_AB~23.0 mag. Less complete data are also available in JKs for the adjacent
HST NICMOS field. For CDF-S, the infrared observations cover a total area of
\~100 square arcmin, reaching median limiting magnitudes (as defined above) of
J_AB~23.6 and K_AB~22.7 mag. For one CDF-S field H-band data are also
available. This paper describes the observations and presents the results of
new reductions carried out entirely through the un-supervised, high-throughput
EIS Data Reduction System and its associated EIS/MVM C++-based image processing
library developed, over the past 5 years, by the EIS project and now publicly
available. The paper also presents source catalogs extracted from the final
co-added images which are used to evaluate the scientific quality of the survey
products, and hence the performance of the software. This is done comparing the
results obtained in the present work with those obtained by other authors from
independent data and/or reductions carried out with different software packages
and techniques. The final science-grade catalogs and co-added images are
available at CDS.Comment: Accepted for publication in A&A, 13 pages, 12 figures; a full
resolution version of the paper is available from
http://www.astro.ku.dk/~lisbeth/eisdata/papers/4528.pdf ; related catalogs
and images are available through http://www.astro.ku.dk/~lisbeth/eisdata
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