9,903 research outputs found
High dispersive and monolithic 100% efficiency grisms
We present a type of grism, a series combination of transmission grating and
prism, in which we reduce the number of diffraction orders and achieve a
configuration with very high angular dispersion. The grism can be fabricated
from a single dielectric material and requires no metallic or dielectric film
layers for high transmission diffraction efficiency. One can reach 100% in the
-1st transmission diffraction order and the equal damage threshold as the
dielectric bulk material. We realized such an element in fused silica with an
efficiency of more then 99%. The bevel backside reflection is reduced by a
statistical antireflective structure, so we measured an efficiency of the
entire grism of 95% at a single wavelength
Ionization by bulk heating of electrons in capacitive radio frequency atmospheric pressure microplasmas
Electron heating and ionization dynamics in capacitively coupled radio
frequency (RF) atmospheric pressure microplasmas operated in helium are
investigated by Particle in Cell simulations and semi-analytical modeling. A
strong heating of electrons and ionization in the plasma bulk due to high bulk
electric fields are observed at distinct times within the RF period. Based on
the model the electric field is identified to be a drift field caused by a low
electrical conductivity due to the high electron-neutral collision frequency at
atmospheric pressure. Thus, the ionization is mainly caused by ohmic heating in
this "Omega-mode". The phase of strongest bulk electric field and ionization is
affected by the driving voltage amplitude. At high amplitudes, the plasma
density is high, so that the sheath impedance is comparable to the bulk
resistance. Thus, voltage and current are about 45{\deg} out of phase and
maximum ionization is observed during sheath expansion with local maxima at the
sheath edges. At low driving voltages, the plasma density is low and the
discharge becomes more resistive resulting in a smaller phase shift of about
4{\deg}. Thus, maximum ionization occurs later within the RF period with a
maximum in the discharge center. Significant analogies to electronegative low
pressure macroscopic discharges operated in the Drift-Ambipolar mode are found,
where similar mechanisms induced by a high electronegativity instead of a high
collision frequency have been identified
Substrate‐assisted activation and selectivity of the bacterial RavD effector deubiquitinylase
A continuous rating method for preferential voting. The complete case
A method is given for quantitatively rating the social acceptance of
different options which are the matter of a complete preferential vote.
Completeness means that every voter expresses a comparison (a preference or a
tie) about each pair of options. The proposed method is proved to have certain
desirable properties, which include: the continuity of the rates with respect
to the data, a decomposition property that characterizes certain situations
opposite to a tie, the Condorcet-Smith principle, and a property of clone
consistency. One can view this rating method as a complement for the ranking
method introduced in 1997 by Markus Schulze. It is also related to certain
methods of one-dimensional scaling or cluster analysis.Comment: This is part one of a revised version of arxiv:0810.2263. Version 3
is the result of certain modifications, both in the statement of the problem
and in the concluding remarks, that enhance the results of the paper; the
results themselves remain unchange
Hybrid protoneutron stars with the MIT bag model
We study the hadron-quark phase transition in the interior of protoneutron
stars. For the hadronic sector, we use a microscopic equation of state
involving nucleons and hyperons derived within the finite-temperature
Brueckner-Bethe-Goldstone many-body theory, with realistic two-body and
three-body forces. For the description of quark matter, we employ the MIT bag
model both with a constant and a density-dependent bag parameter. We calculate
the structure of protostars with the equation of state comprising both phases
and find maximum masses below 1.6 solar masses. Metastable heavy hybrid
protostars are not found.Comment: 12 pages, 9 figures submitted to Phys. Rev.
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