314 research outputs found
D 3.1 Guidance for scoring levels of risk supplied via hypertext links within each component of the web-based EPPO PRA scheme
The Cosmic-Ray Proton and Helium Spectra measured with the CAPRICE98 balloon experiment
A new measurement of the primary cosmic-ray proton and helium fluxes from 3
to 350 GeV was carried out by the balloon-borne CAPRICE experiment in 1998.
This experimental setup combines different detector techniques and has
excellent particle discrimination capabilities allowing clear particle
identification. Our experiment has the capability to determine accurately
detector selection efficiencies and systematic errors associated with them.
Furthermore, it can check for the first time the energy determined by the
magnet spectrometer by using the Cherenkov angle measured by the RICH detector
well above 20 GeV/n. The analysis of the primary proton and helium components
is described here and the results are compared with other recent measurements
using other magnet spectrometers. The observed energy spectra at the top of the
atmosphere can be represented by (1.27+-0.09)x10^4 E^(-2.75+-0.02) particles
(m^2 GeV sr s)^-1, where E is the kinetic energy, for protons between 20 and
350 GeV and (4.8+-0.8)x10^2 E^(-2.67+-0.06) particles (m^2 GeV nucleon^-1 sr
s)^-1, where E is the kinetic energy per nucleon, for helium nuclei between 15
and 150 GeV nucleon^-1.Comment: To be published on Astroparticle Physics (44 pages, 13 figures, 5
tables
Measurement of the flux of atmospheric muons with the CAPRICE94 apparatus
A new measurement of the momentum spectra of both positive and negative muons
as function of atmospheric depth was made by the balloon-borne experiment
CAPRICE94. The data were collected during ground runs in Lynn Lake on the
19-20th of July 1994 and during the balloon flight on the 8-9th of August 1994.
We present results that cover the momentum intervals 0.3-40 GeV/c for negative
muons and 0.3-2 GeV/c for positive muons, for atmospheric depths from 3.3 to
1000 g/cm**2, respectively. Good agreement is found with previous measurements
for high momenta, while at momenta below 1 GeV/c we find latitude dependent
geomagnetic effects. These measurements are important cross-checks for the
simulations carried out to calculate the atmospheric neutrino fluxes and to
understand the observed atmospheric neutrino anomaly.Comment: 28 pages, 13 Postscript figures, uses revtex.sty, to appear in Phys.
Rev.
Measurements of cosmic-ray electrons and positrons by the Wizard/CAPRICE collaboration
Two recent ballon-borne experiments have been performed by the WiZard/CAPRICE collaboration in order to study the electron and positron components in the cosmic radiation.
On 1994 August 8–9 the CAPRICE94 experiment flew from norther Canada and on 1998 May 28–29 the CAPRICE98 experiment flew from New Mexico, USA at altitudes corresponding to 3.9 and 5.5 g/cm2 of average residual atmosphere respectively. The apparatus were equipped with a Ring Imaging Cherenkov (RICH) detector, a time-of-flight system, a superconducting magnet spectrometer with a tracking system and a 7-radiation-length silicon-tungsten imaging calorimeter. The RICH used in 1994 had a solid NaF radiator while in 1998 the RICH had a C4F10 gaseous radiator.
We report on the electron and positron spectra and positron fraction at the top of the atmosphere from few hundred MeV to 40 GeV measured by these two experiments
The Cosmic-Ray antiproton flux between 3 and 49 GeV
We report on a new measurement of the cosmic ray antiproton spectrum. The
data were collected by the balloon-borne experiment CAPRICE98 which was flown
on 28-29 May 1998 from Fort Sumner, New Mexico, USA. The experiment used the
NMSU-WIZARD/CAPRICE98 balloon-borne magnet spectrometer equipped with a gas
Ring Imaging Cherenkov (RICH) detector, a time-of-flight system, a tracking
device consisting of drift chambers and a superconducting magnet and a
silicon-tungsten calorimeter. The RICH detector was the first ever flown
capable of mass-resolving charge-one particles at energies above 5 GeV.
A total of 31 antiprotons with rigidities between 4 and 50 GV at the
spectrometer were identified with small backgrounds from other particles. The
absolute antiproton energy spectrum was determined in the kinetic energy region
at the top of the atmosphere between 3.2 and 49.1 GeV. We found that the
observed antiproton spectrum and the antiproton-to-proton ratio are consistent
with a pure secondary origin. However, a primary component may not be excluded.Comment: 39 pages, 11 Postscript figures, uses AAS LATEX style; changes in
sections 3.1.1, 3.3, 3.4 and 6, Figure 8 modified, 2 figures added, typos
correcte
A high resolution search for the tensor glueball candidate [xi] (2230) Crystal Barrel Collaboration
We report results of a high resolution search for the tensor glueball candidate ξ(2230) in a p̄p formation experiment. π0π0 and ηη decay channels were measured in a scan of the mass region 2220 MeV to 2240 MeV. No evidence for the existence of ξ(2230) was found. 95% confidence upper limits for the possible existence of ξ are presented
PLoS Pathog
Kaposi's sarcoma herpesvirus (KSHV) encodes a cluster of twelve micro (mi)RNAs, which are abundantly expressed during both latent and lytic infection. Previous studies reported that KSHV is able to inhibit apoptosis during latent infection; we thus tested the involvement of viral miRNAs in this process. We found that both HEK293 epithelial cells and DG75 cells stably expressing KSHV miRNAs were protected from apoptosis. Potential cellular targets that were significantly down-regulated upon KSHV miRNAs expression were identified by microarray profiling. Among them, we validated by luciferase reporter assays, quantitative PCR and western blotting caspase 3 (Casp3), a critical factor for the control of apoptosis. Using site-directed mutagenesis, we found that three KSHV miRNAs, miR-K12-1, 3 and 4-3p, were responsible for the targeting of Casp3. Specific inhibition of these miRNAs in KSHV-infected cells resulted in increased expression levels of endogenous Casp3 and enhanced apoptosis. Altogether, our results suggest that KSHV miRNAs directly participate in the previously reported inhibition of apoptosis by the virus, and are thus likely to play a role in KSHV-induced oncogenesis
A thousand-genome panel retraces the global spread and adaptation of a major fungal crop pathogen
Human activity impacts the evolutionary trajectories of many species worldwide. Global trade of agricultural goods contributes to the dispersal of pathogens reshaping their genetic makeup and providing opportunities for virulence gains. Understanding how pathogens surmount control strategies and cope with new climates is crucial to predicting the future impact of crop pathogens. Here, we address this by assembling a global thousand-genome panel of Zymoseptoria tritici, a major fungal pathogen of wheat reported in all production areas worldwide. We identify the global invasion routes and ongoing genetic exchange of the pathogen among wheat-growing regions. We find that the global expansion was accompanied by increased activity of transposable elements and weakened genomic defenses. Finally, we find significant standing variation for adaptation to new climates encountered during the global spread. Our work shows how large population genomic panels enable deep insights into the evolutionary trajectory of a major crop pathogen
Some reasons why the latent period should not always be considered constant over the course of a plant disease epidemic
The latent period is a crucial life history trait, particularly for polycyclic plant diseases, because it determines how many complete infection cycles could theoretically occur during an epidemic. Experiments in controlled conditions are generally used to assess pathogenicity and host susceptibility, and also provide the opportunity to measure the distribution of latent periods in epidemiological systems. Once estimated for one or several pairs of host–pathogen genotypes, the mean value of this trait is usually considered to be fixed and is often used ‘as is’ in models. This review contends that the latent period can display non-negligible variability over the course of a disease epidemic, and that this variability has multiple sources, some of which have complex, antagonistic impacts. Arguments are developed for four sources of variation challenging the assumption that the latent period remains constant: (i) daily fluctuations in host temperature (or other organ–environment factors); (ii) nature of inoculum; (iii) host stage or age of host tissues; and (iv) intrapopulation competition and selection for aggressiveness traits. The review is focused on the wheat pathogen Zymoseptoria tritici, making use of empirical datasets collected during the first author's research projects and a targeted literature review. Such empirical epidemiological knowledge is potentially important for epidemiological modellers. While some studies have demonstrated that the distribution of latent periods around the mean value has consequences for epidemiological dynamics, it is shown here that it might also be important for modellers to account for changes in this mean value during an epidemic. These results may be critical for improving epidemic forecasting
Some reasons why the latent period should not always be considered constant over the course of a plant disease epidemic
The latent period is a crucial life history trait, particularly for polycyclic plant diseases, because it determines how many complete infection cycles could theoretically occur during an epidemic. Experiments in controlled conditions are generally used to assess pathogenicity and host susceptibility, and also provide the opportunity to measure the distribution of latent periods in epidemiological systems. Once estimated for one or several pairs of host–pathogen genotypes, the mean value of this trait is usually considered to be fixed and is often used ‘as is’ in models. This review contends that the latent period can display non-negligible variability over the course of a disease epidemic, and that this variability has multiple sources, some of which have complex, antagonistic impacts. Arguments are developed for four sources of variation challenging the assumption that the latent period remains constant: (i) daily fluctuations in host temperature (or other organ–environment factors); (ii) nature of inoculum; (iii) host stage or age of host tissues; and (iv) intrapopulation competition and selection for aggressiveness traits. The review is focused on the wheat pathogen Zymoseptoria tritici, making use of empirical datasets collected during the first author's research projects and a targeted literature review. Such empirical epidemiological knowledge is potentially important for epidemiological modellers. While some studies have demonstrated that the distribution of latent periods around the mean value has consequences for epidemiological dynamics, it is shown here that it might also be important for modellers to account for changes in this mean value during an epidemic. These results may be critical for improving epidemic forecasting
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