1,208 research outputs found
Detection of Noble Gas Scintillation Light with Large Area Avalanche Photodiodes (LAAPDs)
Large Area Avalanche Photodiodes (LAAPDs) were used for a series of
systematic measurements of the scintillation light in Ar, Kr, and Xe gas.
Absolute quantum efficiencies are derived. Values for Xe and Kr are consistent
with those given by the manufacturer. For the first time we show that argon
scintillation (128 nm) can be detected at a quantum efficiency above 40%.
Low-pressure argon gas is shown to emit significant amounts of non-UV
radiation. The average energy expenditure for the creation of non-UV photons in
argon gas at this pressure is measured to be below 378 eV.Comment: 16 pages, 7 figure
SOLUTION OF THE COUPLED THERMOMECHANICAL PROBLEM OF HYDRODYNAMICS FOR DESIGNING THE PROPULSION SYSTEM OF MICROSATELLITES
This paper considers the problem of predicting the technical and operating characteristics of the propulsion
system of a microsatellite created by microelectronic technology. The coupled thermomechanical problem of
hydrodynamics has been solved by the ANSYS CFX package. The microengine design has been optimized, the
heating of its case in the operating time of the fuel chamber has been analyzed, and the velocity field distribution
in the microengine nozzle has been determined. The values of the mechanical and temperature deformation
fields for pure silicon and a silicon–SiO2 composite have been found, and the possibility in principle
of operation of the considered device has been shown. The calculation was made on a triangular net
On the Underground Production of High Purity Germanium Detectors
Detectors based on high purity germanium (HPGe) are used in numerous deep underground experiments world-wide aiming at detecting rare events like double beta decay and interactions of dark matter. These detectors require the lowest possible background. A significant part of the background is due to radionuclides produced by cosmic-ray interactions with the germanium crystal. This report gives quantitative data on this activation and discusses the possible solutions. The first solution is to optimise the logistics during the crystal and detector fabrication so that the germanium spends a minimum time above ground. The second solution is to implement one or several (up to 12) production steps underground. The report also makes estimates on the future needs for germanium produced underground and the costs involved.JRC.D.4-Isotope measurement
The Pied Piper of Hamelin and Other Melodramas
Research in and through artistic practic
NusG inhibits RNA polymerase backtracking by stabilizing the minimal transcription bubble
Universally conserved factors from NusG family bind at the upstream fork
junction of transcription elongation complexes and modulate RNA
synthesis in response to translation, processing, and folding of the
nascent RNA. Escherichia coli NusG enhances transcription elongation in vitro by a poorly understood mechanism. Here we report that E. coli
NusG slows Gre factor-stimulated cleavage of the nascent RNA, but does
not measurably change the rates of single nucleotide addition and
translocation by a non-paused RNA polymerase. We demonstrate that NusG
slows RNA cleavage by inhibiting backtracking. This activity is
abolished by mismatches in the upstream DNA and is independent of the
gate and rudder loops, but is partially dependent on the lid loop. Our
comprehensive mapping of the upstream fork junction by base analogue
fluorescence and nucleic acids crosslinking suggests that NusG inhibits
backtracking by stabilizing the minimal transcription bubble.</p
Peptides against autoimmune neurodegeneration
© 2017 Bentham Science Publishers. The mammalian immune system is a nearly perfect defensive system polished by a hundred million years of evolution. Unique flexibility and adaptivity have created a virtually impenetrable barrier to numerous exogenous pathogens that are assaulting us every moment. Unfortunately, triggers that remain mostly enigmatic will sometimes persuade the immune system to retarget against self-antigens. This civil war remains underway, showing no mercy and taking no captives, eventually leading to irreversible pathological changes in the human body. Research that has emerged during the last two decades has given us hope that we may have a chance to overcome autoimmune diseases using a variety of techniques to "reset" the immune system. In this report, we summarize recent advances in utilizing short polypeptides - mostly fragments of autoantigens - in the treatment of autoimmune neurodegeneration
Cosmogenic activation of Germanium and its reduction for low background experiments
Production of Co and Ge from stable isotopes of Germanium by
nuclear active component of cosmic rays is a principal background source for a
new generation of Ge double beta decay experiments like GERDA and
Majorana. The biggest amount of cosmogenic activity is expected to be produced
during transportation of either enriched material or already grown crystal.
In this letter properties and feasibility of a movable iron shield are
discussed. Activation reduction factor of about 10 is predicted by simulations
with SHIELD code for a simple cylindrical configuration. It is sufficient for
GERDA Phase II background requirements. Possibility of further increase of
reduction factor and physical limitations are considered. Importance of
activation reduction during Germanium purification and detector manufacturing
is emphasized.Comment: 10 pages, 3 tables, 6 figure
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