915 research outputs found
Rabbit haemorrhagic disease: Cross-protection and comparative pathogenicity of GI.2/RHDV2/b and GI.1b/RHDV lagoviruses in a challenge trial
European rabbits (Oryctolagus cuniculus) are severely affected by rabbit haemorrhagic disease (RHD). Caused by a lagovirus, the disease leads to losses in the rabbit industry and has implications for wildlife conservation. Past RHD outbreaks have been caused by GI.1/RHDV genotype viruses. A new virus belonging to the GI.2/RHDV2/b genotype emerged in 2010, quickly spreading and replacing the former in several countries; however, limited data are available on its pathogenicity and epidemiological factors. The present work extends these issues and evaluates cross-protection between both genotypes. Ninety-four and 88 domestic rabbits were challenged with GI.2/RHDV2/b and GI.1b/RHDV variant isolates, respectively. Cross-protection was determined by a second challenge on survivors with the corresponding strain. Mortality by GI.2/RHDV2/b was highly variable due to unknown individual factors, whereas mortality by GI.1b/RHDV was associated with age. Mortality in rabbits < 4 weeks old was 84%, higher than previously reported. Cross-protection was not identical between the two viruses because the ratio of mortality rate ratios for the first and second challenges was 3.80 ± 2.68 times higher for GI.2/RHDV2/b than it was for GI.1b/RHDV. Rabbit susceptibility to GI.2/RHDV2/b varied greatly and appeared to be modulated by the innate functionality of the immune response and/or its prompt activation by other pathogens. GI.1b/RHDV pathogenicity appeared to be associated with undetermined age-related factors. These results suggest that GI.2/RHDV2/b may interact with other pathogens at the population level but does not satisfactorily explain the GI.1b/RHDV virus's quick replacement
Detection of Rabbit Hemorrhagic Disease Virus GI.2/RHDV2/b in the Mediterranean Pine Vole ( Microtus duodecimcostatus) and White-Toothed Shrew ( Crocidura russula)
The European wild rabbit ( Oryctolagus cuniculus) is a key prey species on the Iberian Peninsula, and several predator species that are at risk of extinction are dependent on them as prey. A new rabbit hemorrhagic disease (RHD) virus genotype (GI.2/RHDV2/b) emerged in 2010 and posed a threat to wild rabbit populations. During a survey aimed at investigating RHD epidemiology in wild rabbits, GI.2/RHDV2/b was detected by duplex real-time PCR in carcasses of one Mediterranean pine vole ( Microtus duodecimcostatus) and two white-toothed shrews ( Crocidura russula). Laboratory New Zealand white rabbits that were challenged with inocula obtained from the liver of the small mammals died showing RHD lesions, confirming the infectiousness of the isolates. Phylogenetic analysis of the VP60 gene nucleotide sequences showed complete homology between the isolates from the two small mammal species and a high degree of similarity, but not complete homology, to GI.2/RHDV2/b sequences from wild rabbits. The GI.2/RHDV2/b genotype has not been reported in species outside the order Lagomorpha
The effect of organic acids on the behaviour and biodegradation of 14C-phenanthrene in contaminated soil
The interaction between root exudates and soil microbes has been hypothesised as the primary mechanism for the biodegradation of organic pollutants in the rhizosphere. However, the mechanisms governing this loss process are not completely understood. This study aimed to investigate the effect of two important compounds within root exudates (citric and malic acid) on 14C-phenanthrene desorption and bioaccessibility in soil. Overall results showed that the presence of both citric and malic acid (>100 mmol l−1) enhanced the desorption of 14C-phenanthrene; this appeared to be concentration dependant. Increases in extractability were not reflected in a higher bioaccessibility. Despite enhancing the desorption of 14C-phenanthrene in soil, there is no direct evidence indicating that citric or malic acid have the ability to promote the biodegradation of 14C-phenanthrene from soil. Results from this study provide a novel understanding of the role that substrates, typically found within the rhizosphere due to root exudation, play in the bioaccessibility and biodegradation of hydrocarbons in contaminated soil
The Approach to Ergodicity in Monte Carlo Simulations
The approach to the ergodic limit in Monte Carlo simulations is studied using
both analytic and numerical methods. With the help of a stochastic model, a
metric is defined that enables the examination of a simulation in both the
ergodic and non-ergodic regimes. In the non-ergodic regime, the model implies
how the simulation is expected to approach ergodic behavior analytically, and
the analytically inferred decay law of the metric allows the monitoring of the
onset of ergodic behavior. The metric is related to previously defined measures
developed for molecular dynamics simulations, and the metric enables the
comparison of the relative efficiencies of different Monte Carlo schemes.
Applications to Lennard-Jones 13-particle clusters are shown to match the model
for Metropolis, J-walking and parallel tempering based approaches. The relative
efficiencies of these three Monte Carlo approaches are compared, and the decay
law is shown to be useful in determining needed high temperature parameters in
parallel tempering and J-walking studies of atomic clusters.Comment: 17 Pages, 7 Figure
Quantum feedback with weak measurements
The problem of feedback control of quantum systems by means of weak
measurements is investigated in detail. When weak measurements are made on a
set of identical quantum systems, the single-system density matrix can be
determined to a high degree of accuracy while affecting each system only
slightly. If this information is fed back into the systems by coherent
operations, the single-system density matrix can be made to undergo an
arbitrary nonlinear dynamics, including for example a dynamics governed by a
nonlinear Schr\"odinger equation. We investigate the implications of such
nonlinear quantum dynamics for various problems in quantum control and quantum
information theory, including quantum computation. The nonlinear dynamics
induced by weak quantum feedback could be used to create a novel form of
quantum chaos in which the time evolution of the single-system wave function
depends sensitively on initial conditions.Comment: 11 pages, TeX, replaced to incorporate suggestions of Asher Pere
EUROfusion-theory and advanced simulation coordination (E-TASC): programme and the role of high performance computing
The paper is a written summary of an overview oral presentation given at the 1st Spanish Fusion HPC Workshop that took place on the 27th November 2020 as an online event. Given that over the next few years ITER will move to its operation phase and the European-DEMO design will be significantly advanced, the EUROfusion consortium has initiated a coordination effort in theory and advanced simulation to address some of the challenges of the fusion research in Horizon EUROPE (2021-2027), i.e. the next EU Framework Programme for Research and Technological Development. This initiative has been called E-TASC that stands for EUROfusion-Theory and Advanced Simulation Coordination. The general and guiding principles of E-TASC are summarized in the paper. In addition, an overview of the scientific results obtained in a pilot phase (2019-2020) of E-TASC are provided while highlighting the importance of the required progress in computational methods and HPC techniques. In the initial phase, five pilot theory and simulation tasks were initiated: 1. Towards a validated predictive capability of the L-H transition and pedestal physics; 2. Electron runaway in tokamak disruptions in the presence of massive material injection; 3. Fast code for the calculation of neoclassical toroidal viscosity in stellarators and tokamaks; 4. Development of a neutral gas kinetics modular code; 5. European edge and boundary code for reactor-relevant devices. In this paper we report on recent progress made by each of these projects.</p
Strange particle production in proton-proton collisions at TeV with ALICE at the LHC
The production of mesons containing strange quarks (K, ) and both
singly and doubly strange baryons (, Anti-, and
+Anti-) are measured at central rapidity in pp collisions at
= 0.9 TeV with the ALICE experiment at the LHC. The results are
obtained from the analysis of about 250 k minimum bias events recorded in 2009.
Measurements of yields (dN/dy) and transverse momentum spectra at central
rapidities for inelastic pp collisions are presented. For mesons, we report
yields () of 0.184 0.002 stat. 0.006 syst. for K and
0.021 0.004 stat. 0.003 syst. for . For baryons, we find
= 0.048 0.001 stat. 0.004 syst. for , 0.047
0.002 stat. 0.005 syst. for Anti- and 0.0101 0.0020 stat.
0.0009 syst. for +Anti-. The results are also compared with
predictions for identified particle spectra from QCD-inspired models and
provide a baseline for comparisons with both future pp measurements at higher
energies and heavy-ion collisions.Comment: 33 pages, 21 captioned figures, 10 tables, authors from page 28,
published version, figures at
http://aliceinfo.cern.ch/ArtSubmission/node/387
Suppression of charged particle production at large transverse momentum in central Pb-Pb collisions at TeV
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb
collisions at = 2.76 TeV have been measured by the ALICE
Collaboration at the LHC. The data are presented for central and peripheral
collisions, corresponding to 0-5% and 70-80% of the hadronic Pb-Pb cross
section. The measured charged particle spectra in and GeV/ are compared to the expectation in pp collisions at the same
, scaled by the number of underlying nucleon-nucleon
collisions. The comparison is expressed in terms of the nuclear modification
factor . The result indicates only weak medium effects ( 0.7) in peripheral collisions. In central collisions,
reaches a minimum of about 0.14 at -7GeV/ and increases
significantly at larger . The measured suppression of high- particles is stronger than that observed at lower collision energies,
indicating that a very dense medium is formed in central Pb-Pb collisions at
the LHC.Comment: 15 pages, 5 captioned figures, 3 tables, authors from page 10,
published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/98
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