2,353 research outputs found
EUREGIO MRSA-net Twente/Munsterland - a Dutch-German cross-border network for the prevention and control of infections caused by methicillin-resistant Staphylococcus aureus
Binary file ES_Abstracts_Final_ECDC.txt matches
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Formation of Hydrogen, Oxygen, and Hydrogen Peroxide in Electron Irradiated Crystalline Water Ice
Water ice is abundant both astrophysically, for example in molecular clouds,
and in planetary systems. The Kuiper belt objects, many satellites of the outer
solar system, the nuclei of comets and some planetary rings are all known to be
water-rich. Processing of water ice by energetic particles and ultraviolet
photons plays an important role in astrochemistry. To explore the detailed
nature of this processing, we have conducted a systematic laboratory study of
the irradiation of crystalline water ice in an ultrahigh vacuum setup by
energetic electrons holding a linear energy transfer of 4.3 +/- 0.1 keV mm-1.
The irradiated samples were monitored during the experiment both on line and in
situ via mass spectrometry (gas phase) and Fourier transform infrared
spectroscopy (solid state). We observed the production of hydrogen and oxygen,
both molecular and atomic, and of hydrogen peroxide. The likely reaction
mechanisms responsible for these species are discussed. Additional formation
routes were derived from the sublimation profiles of molecular hydrogen (90-140
K), molecular oxygen (147 -151 K) and hydrogen peroxide (170 K). We also
present evidence on the involvement of hydroxyl radicals and possibly oxygen
atoms as building blocks to yield hydrogen peroxide at low temperatures (12 K)
and via a diffusion-controlled mechanism in the warming up phase of the
irradiated sample.Comment: ApJ, March 2006, v639 issue, 43 pages, 7 figure
Energy spectrum of turbulent fluctuations in boundary driven reduced magnetohydrodynamics
The nonlinear dynamics of a bundle of magnetic flux ropes driven by
stationary fluid motions at their endpoints is studied, by performing numerical
simulations of the magnetohydrodynamic (MHD) equations. The development of MHD
turbulence is shown, where the system reaches a state that is characterized by
the ratio between the Alfven time (the time for incompressible MHD waves to
travel along the field lines) and the convective time scale of the driving
motions. This ratio of time scales determines the energy spectra and the
relaxation toward different regimes ranging from weak to strong turbulence. A
connection is made with phenomenological theories for the energy spectra in MHD
turbulence.Comment: Published in Physics of Plasma
Genome landscapes and bacteriophage codon usage
Across all kingdoms of biological life, protein-coding genes exhibit unequal
usage of synonmous codons. Although alternative theories abound, translational
selection has been accepted as an important mechanism that shapes the patterns
of codon usage in prokaryotes and simple eukaryotes. Here we analyze patterns
of codon usage across 74 diverse bacteriophages that infect E. coli, P.
aeruginosa and L. lactis as their primary host. We introduce the concept of a
`genome landscape,' which helps reveal non-trivial, long-range patterns in
codon usage across a genome. We develop a series of randomization tests that
allow us to interrogate the significance of one aspect of codon usage, such a
GC content, while controlling for another aspect, such as adaptation to
host-preferred codons. We find that 33 phage genomes exhibit highly non-random
patterns in their GC3-content, use of host-preferred codons, or both. We show
that the head and tail proteins of these phages exhibit significant bias
towards host-preferred codons, relative to the non-structural phage proteins.
Our results support the hypothesis of translational selection on viral genes
for host-preferred codons, over a broad range of bacteriophages.Comment: 9 Color Figures, 5 Tables, 53 Reference
Turbulent Coronal Heating Mechanisms: Coupling of Dynamics and Thermodynamics
Context. Photospheric motions shuffle the footpoints of the strong axial
magnetic field that threads coronal loops giving rise to turbulent nonlinear
dynamics characterized by the continuous formation and dissipation of
field-aligned current sheets where energy is deposited at small-scales and the
heating occurs. Previous studies show that current sheets thickness is orders
of magnitude smaller than current state of the art observational resolution
(~700 km).
Aim. In order to understand coronal heating and interpret correctly
observations it is crucial to study the thermodynamics of such a system where
energy is deposited at unresolved small-scales.
Methods. Fully compressible three-dimensional magnetohydrodynamic simulations
are carried out to understand the thermodynamics of coronal heating in the
magnetically confined solar corona.
Results. We show that temperature is highly structured at scales below
observational resolution and nonhomogeneously distributed so that only a
fraction of the coronal mass and volume gets heated at each time.
Conclusions. This is a multi-thermal system where hotter and cooler plasma
strands are found one next to the other also at sub-resolution scales and
exhibit a temporal dynamics.Comment: A&A Letter, in pres
Reduction of the nosocomial meticillin-resistant Staphylococcus aureus incidence density by a region-wide search and follow-strategy in forty German hospitals of the EUREGIO, 2009 to 2011
Meticillin-resistant Staphylococcus aureus (MRSA) disseminates between hospitals serving one patient catchment area. Successful prevention and control requires concerted efforts and regional surveillance. Forty hospitals located in the German EUREGIO have established a network for combating MRSA. In 2007 they agreed upon a synchronised strategy for screening of risk patients and a standard for transmissionbased precautions (search and follow). The same year, the hospitals started synchronised MRSA prevention and annually reporting MRSA-data to the public health authorities. The median rate of screening cultures per 100 patients admitted increased from 4.38 in 2007 to 34.4 in 2011 (p<0.0001). Between 2007 and 2011, the overall incidence density of MRSA (0.87 MRSA cases/1,000 patient days vs 1.54; p<0.0001) increased significantly. In contrast, both the incidence density of nosocomial MRSA cases (0.13 nosocomial MRSA cases/1,000 patient days in 2009 vs 0.08 in 2011; p=0.0084) and the MRSA-days-associated nosocomial MRSA rate (5.51 nosocomial MRSA cases/1,000 MRSA days in 2009 vs 3.80 in 2011; p=0.0437) decreased significantly after the second year of the project. We documented adherence to the regional screening strategy resulting in improved detection of MRSA carriers at admission. Subsequently, after two years the nosocomial MRSA-incidence density was reduced. Regional surveillance data, annually provided as benchmarking to the regional hospitals and public health authorities, indicated successful prevention.</p
Equilibrium Sampling From Nonequilibrium Dynamics
We present some applications of an Interacting Particle System (IPS)
methodology to the field of Molecular Dynamics. This IPS method allows several
simulations of a switched random process to keep closer to equilibrium at each
time, thanks to a selection mechanism based on the relative virtual work
induced on the system. It is therefore an efficient improvement of usual
non-equilibrium simulations, which can be used to compute canonical averages,
free energy differences, and typical transitions paths
A New Understanding of the Europa Atmosphere and Limits on Geophysical Activity
Deep extreme ultraviolet spectrograph exposures of the plasma sheet at the orbit of Europa, obtained in 2001 using the Cassini Ultraviolet Imaging Spectrograph experiment, have been analyzed to determine the state of the gas. The results are in basic agreement with earlier results, in particular with Voyager encounter measurements of electron density and temperature. Mass loading rates and lack of detectable neutrals in the plasma sheet, however, are in conflict with earlier determinations of atmospheric composition and density at Europa. A substantial fraction of the plasma species at the Europa orbit are long-lived sulfur ions originating at Io, with ~25% derived from Europa. During the outward radial diffusion process to the Europa orbit, heat deposition forces a significant rise in plasma electron temperature and latitudinal size accompanied with conversion to higher order ions, a clear indication that mass loading from Europa is very low. Analysis of far ultraviolet spectra from exposures on Europa leads to the conclusion that earlier reported atmospheric measurements have been misinterpreted. The results in the present work are also in conflict with a report that energetic neutral particles imaged by the Cassini ion and neutral camera experiment originate at the Europa orbit. An interpretation of persistent energetic proton pitch angle distributions near the Europa orbit as an effect of a significant population of neutral gas is also in conflict with the results of the present work. The general conclusion drawn here is that Europa is geophysically far less active than inferred in previous research, with mass loading of the plasma sheet ≤4.5 x 10^(25) atoms s^(-1) two orders of magnitude below earlier published calculations. Temporal variability in the region joining the Io and Europa orbits, based on the accumulated evidence, is forced by the response of the system to geophysical activity at Io. No evidence for the direct injection of H_2O into the Europa atmosphere or from Europa into the magnetosphere system, as has been observed at Enceladus in the Saturn system, is obtained in the present investigation
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