293 research outputs found
The wavefront of the radio signal emitted by cosmic ray air showers
Analyzing measurements of the LOPES antenna array together with corresponding
CoREAS simulations for more than 300 measured events with energy above
eV and zenith angles smaller than , we find that the radio
wavefront of cosmic-ray air showers is of approximately hyperbolic shape. The
simulations predict a slightly steeper wavefront towards East than towards
West, but this asymmetry is negligible against the measurement uncertainties of
LOPES. At axis distances m, the wavefront can be approximated by
a simple cone. According to the simulations, the cone angle is clearly
correlated with the shower maximum. Thus, we confirm earlier predictions that
arrival time measurements can be used to study the longitudinal shower
development, but now using a realistic wavefront. Moreover, we show that the
hyperbolic wavefront is compatible with our measurement, and we present several
experimental indications that the cone angle is indeed sensitive to the shower
development. Consequently, the wavefront can be used to statistically study the
primary composition of ultra-high energy cosmic rays. At LOPES, the
experimentally achieved precision for the shower maximum is limited by
measurement uncertainties to approximately g/cm. But the simulations
indicate that under better conditions this method might yield an accuracy for
the atmospheric depth of the shower maximum, , better than
g/cm. This would be competitive with the established air-fluorescence
and air-Cherenkov techniques, where the radio technique offers the advantage of
a significantly higher duty-cycle. Finally, the hyperbolic wavefront can be
used to reconstruct the shower geometry more accurately, which potentially
allows a better reconstruction of all other shower parameters, too.Comment: accepted by JCA
Biodegradative mechanism of the brown rot basidiomycete Gloeophyllum trabeum: evidence for an extracellular hydroquinone-driven fenton reaction
AbstractWe have identified key components of the extracellular oxidative system that the brown rot fungus Gloeophyllum trabeum uses to degrade a recalcitrant polymer, polyethylene glycol, via hydrogen abstraction reactions. G. trabeum produced an extracellular metabolite, 2,5-dimethoxy-1,4-benzoquinone, and reduced it to 2,5-dimethoxyhydroquinone. In the presence of 2,5-dimethoxy-1,4-benzoquinone, the fungus also reduced extracellular Fe3+ to Fe2+ and produced extracellular H2O2. Fe3+ reduction and H2O2 formation both resulted from a direct, non-enzymatic reaction between 2,5-dimethoxyhydroquinone and Fe3+. polyethylene glycol depolymerization by G. trabeum required both 2,5-dimethoxy-1,4-benzoquinone and Fe3+ and was completely inhibited by catalase. These results provide evidence that G. trabeum uses a hydroquinone-driven Fenton reaction to cleave polyethylene glycol. We propose that similar reactions account for the ability of G. trabeum to attack lignocellulose
The Influence of Victim Vulnerability and Gender on Police Officersâ Assessment of Intimate Partner Violence Risk
This study investigated the influence of victim vulnerability factors and gender on risk assessment for intimate partner violence (IPV). 867 cases of male and female perpetrated IPV investigated by Swedish police officers using the Brief Spousal Assault Form for the Evaluation of Risk (BSAFER) were examined. For male-to-female IPV, victim vulnerability factors were associated with summary risk judgments and risk management recommendations. For femaleto-male IPV, vulnerability factors were more often omitted, and consistent associations were not found between vulnerability
factors, summary risk judgments, and risk management. Results indicate that B-SAFER victim vulnerability factors can assist in assessing male-to-female IPV risk. Further research is necessary to examine the use of B-SAFER victim vulnerability factors for female-to-male IPV, as results showed victim vulnerability factors to be less relevant to officersâ decision making, particularly their management recommendations. However, several variables external to the B-SAFER, such as the availability of management strategies may account for these findings
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