115 research outputs found
Norwalk Virus–specific Binding to Oyster Digestive Tissues
Specific binding of virus to oysters can selectively concentrate a human pathogen
From the Circumnuclear Disk in the Galactic Center to thick, obscuring tori of AGNs: modeling the molecular emission of a parsec-scale torus as found in NGC 1068
Galaxie
Porcine Noroviruses Related to Human Noroviruses
Pigs may be reservoirs for human noroviruses, and porcine/human genogroup II recombinants could emerge
The starburst-AGN connection in the merger galaxy Mrk 938: an infrared and X-ray view
Mrk938 is a luminous infrared galaxy in the local Universe believed to be the
remnant of a galaxy merger. It shows a Seyfert 2 nucleus and intense star
formation according to optical spectroscopic observations. We have studied this
galaxy using new Herschel far-IR imaging data in addition to archival X-ray,
UV, optical, near-IR and mid-IR data. Mid- and far-IR data are crucial to
characterise the starburst contribution, allowing us to shed new light on its
nature and to study the coexistence of AGN and starburst activity in the local
Universe. The decomposition of the mid-IR Spitzer spectrum shows that the AGN
bolometric contribution to the mid-IR and total infrared luminosity is small
(Lbol(AGN)/LIR~0.02), which agrees with previous estimations. We have
characterised the physical nature of its strong infrared emission and
constrained it to a relatively compact emitting region of <2kpc. It is in this
obscured region where most of the current star formation activity is taking
place as expected for LIRGs. We have used Herschel imaging data for the first
time to constrain the cold dust emission with unprecedented accuracy. We have
fitted the integrated far-IR spectral energy distribution and derived the
properties of the dust, obtaining a dust mass of 3x10^7Msun. The far-IR is
dominated by emission at 35K, consistent with dust heated by the on-going star
formation activity.Comment: 12 pages, 6 figures, 4 tables, accepted for publication in MNRA
EFSA Panel on Biological Hazards (BIOHAZ); Norovirus (NoV) in oysters: methods, limits and control options
Use of Norovirus Genotype Profiles to Differentiate Origins of Foodborne Outbreaks
Detection should enable containment of viral foodborne infections
Mid-infrared spectroscopy of infrared-luminous galaxies at z~0.5-3
We present results on low-resolution mid-infrared (MIR) spectra of 70
infrared-luminous galaxies obtained with the Infrared Spectrograph (IRS)
onboard Spitzer. We selected sources from the European Large Area Infrared
Survey (ELAIS) with S15 > 0.8 mJy and photometric or spectroscopic z > 1. About
half of the sample are QSOs in the optical, while the remaining sources are
galaxies, comprising both obscured AGN and starbursts. We classify the spectra
using well-known infrared diagnostics, as well as a new one that we propose,
into three types of source: those dominated by an unobscured AGN (QSOs),
obscured AGN, and starburst-dominated sources. Starbursts concentrate at z ~
0.6-1.0 favored by the shift of the 7.7-micron PAH band into the selection 15
micron band, while AGN spread over the 0.5 < z < 3.1 range. Star formation
rates (SFR) are estimated for individual sources from the luminosity of the PAH
features. An estimate of the average PAH luminosity in QSOs and obscured AGN is
obtained from the composite spectrum of all sources with reliable redshifts.
The estimated mean SFR in the QSOs is 50-100 Mo yr^-1, but the implied FIR
luminosity is 3-10 times lower than that obtained from stacking analysis of the
FIR photometry, suggesting destruction of the PAH carriers by energetic photons
from the AGN. The SFR estimated in obscured AGN is 2-3 times higher than in
QSOs of similar MIR luminosity. This discrepancy might not be due to luminosity
effects or selection bias alone, but could instead indicate a connection
between obscuration and star formation. However, the observed correlation
between silicate absorption and the slope of the near- to mid-infrared spectrum
is compatible with the obscuration of the AGN emission in these sources being
produced in a dust torus.Comment: 32 pages, 24 figures, 15 tables, accepted for publication in MNRA
Progress in paleoclimate modeling
International audienceThis paper briefly surveys areas of paleoclimate modeling notable for recent progress. New ideas, including hypotheses giving a pivotal role to sea ice, have revitalized the low-order models used to simulate the time evolution of glacial cycles through the Pleistocene, a prohibitive length of time for comprehensive general circulation models (GCMs). In a recent breakthrough, however, GCMs have succeeded in simulating the onset of glaciations. This occurs at times (most recently, 115 kyr B.P.) when high northern latitudes are cold enough to maintain a snow cover and tropical latitudes are warm, enhancing the moisture source. More generally, the improvement in models has allowed simulations of key periods such as the Last Glacial Maximum and the mid-Holocene that compare more favorably and in more detail with paleoproxy data. These models now simulate ENSO cycles, and some of them have been shown to reproduce the reduction of ENSO activity observed in the early to middle Holocene. Modeling studies have demonstrated that the reduction is a response to the altered orbital configuration at that time. An urgent challenge for paleoclimate modeling is to explain and to simulate the abrupt changes observed during glacial epochs (i.e., Dansgaard-Oescher cycles, Heinrich events, and the Younger Dryas). Efforts have begun to simulate the last millennium. Over this time the forcing due to orbital variations is less important than the radiance changes due to volcanic eruptions and variations in solar output. Simulations of these natural variations test the models relied on for future climate change projections. They provide better estimates of the internal and naturally forced variability at centennial time scales, elucidating how unusual the recent global temperature trends are
Flat-spectrum symmetric objects with ~1 kpc sizes I. The candidates
In order to understand the origin and evolution of radio galaxies, searches
for the youngest such sources have been conducted. Compact-medium symmetric
objects (CSO-MSOs) are thought to be the earliest stages of radio sources, with
possible ages of <10^3 yrs for CSOs (<1 kpc in size) and 10^4-10^5 yrs for MSOs
(1-15 kpc). From a literature selection in heterogeneous surveys, we have
established a sample of 37 confirmed CSOs. In addition, we only found three
confirmed flat-spectrum MSOs in the literature.
The typical CSO resides on a z<0.5 galaxy, has a flat radio spectrum
(a_thin<0.5; S_v proportional to v^-a), is <0.3 kpc in size, has an arm length
ratio <2, and well-aligned (theta<20 deg) opposite lobes with a flux density
ratio <10. In order to populate the 0.3-1 kpc size range (large CSOs) and also
in order to find more flat-spectrum MSOs, we have built a sample of 157 radio
sources with a_{1.40}^{4.85}<0.5 that were resolved with the VLA-A 8.4 GHz. As
first results, we have 'rediscovered' nine of the known CSO/MSOs while
identifying two new ~14 kpc MSOs and two candidate CSO/MSOs (which only lack
redshifts for final classification). We were able to reject 61 of the remaining
144 objects from literature information alone. In the series of papers that
starts with this one we plan to classify the remaining 83 CSO/MSO candidates
(thanks to radio and optical observations) as well as characterize the physical
properties of the (likely) many 0.3-15 kpc flat-spectrum CSO/MSOs to be found.Comment: 19 pages, 14 figures, 6 tables (note that Table 2, in landscape
format, has a separate file); accepted by MNRA
Foodborne norovirus outbreak: the role of an asymptomatic food handler
Background: In July 2005 an outbreak of acute gastroenteritis occurred on a residential summer camp in the province of Barcelona (northeast of Spain). Forty-four people were affected among residents and employees. All of them had in common a meal at lunch time on 13 July (paella, round of beef and fruit). The aim of this study was to investigate a foodborne norovirus outbreak that occurred in the residential summer camp and in which the implication of a food handler was demonstrated by laboratory tests. Methods: A retrospective cohort study was designed. Personal or telephone interview was carried out to collect demographic, clinical and microbiological data of the exposed people, as well as food consumption in the suspected lunch. Food handlers of the mentioned summer camp were interviewed. Ten stool samples were requested from symptomatic exposed residents and the three food handlers that prepared the suspected food. Stools were tested for bacteries and noroviruses. Norovirus was detected using RT-PCR and sequence analysis. Attack rate, relative risks (RR) and its 95% confidence intervals (CI) were calculated to assess the association between food consumption and disease. Results: The global attack rate of the outbreak was 55%. The main symptoms were abdominal pain (90%), nausea (85%), vomiting (70%) and diarrhoea (42.5%). The disease remitted in 24-48 hours. Norovirus was detected in seven faecal samples, one of them was from an asymptomatic food handler who had not eaten the suspected food (round of beef), but cooked and served the lunch. Analysis of the two suspected foods isolated no pathogenic bacteria and detected no viruses. Molecular analysis showed that the viral strain was the same in ill patients and in the asymptomatic food handler (genotype GII.2 Melksham-like). Conclusions: In outbreaks of foodborne disease, the search for viruses in affected patients and all food handlers, even in those that are asymptomatic, is essential. Health education of food handlers with respect to hand washing should be promoted
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