9,498 research outputs found
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
Growth and Investigation of Nd_{1-x}Sm_{x}ScO_{3} and Sm_{1-x}Gd_{x}ScO_{3} Solid-Solution Single Crystals
The pseudo-cubic lattice parameters of rare-earth (RE) scandate, REScO3,
single crystals grown by the Czochralski technique with RE=Dy to Pr lie between
about 3.95 and 4.02 Angstrom. These crystals are the only available perovskite
substrates in this lattice constant range that can withstand virtually any thin
film growth conditions. Two members of this series, PmScO3 and EuScO3, are,
however, not suitable for substrate applications. Because the pseudo-cubic
lattice parameters between neighbouring REScO3 compounds decrease with rising
atomic number of the RE in about 0.01 Angstrom steps, the unsuitability of
PmScO3 (radioactivity) and EuScO3 (incompatibility with Si) causes an
interruption in this lattice spacing sequence. To replace them, solid solutions
of their adjacent rare-earth scandates, i.e., (Nd0.5Sm0.5)ScO3 and
(Sm0.5Gd0.5)ScO3, were grown by the Czochralski method. Their average
pseudo-cubic lattice parameters of 3.9979 Angstrom and 3.9784 Angstrom are very
close to those of PmScO3 and EuScO3, respectively, and they show very low
segregation. These qualities make these solid solutions excellent substitutes
for PmScO3 and EuScO3.Comment: 16 pages, 6 figures, 6 table
A COMPARISON OF HYPOTHETICAL PHONE AND MAIL CONTINGENT VALUATION RESPONSES FOR GREEN PRICING ELECTRICITY PROGRAMS
To date, much of the policy and research debate on contingent valuation mode effects has relied on experiences drawn from other research disciplines. This study provides the first contingent valuation phone-mail comparison that meets current standards for response rates, draws from a general population, is relevant to the valuation of general environmental goods, and allows comparisons with actual sign-ups. Consistent with previous research in other disciplines, social desirability bias is found in responses to subjective questions --thus leading to more environmentally favorable responses on the phone. However, this effect does not carry over to hypothetical participation decisions. Hypothetical bias is found in both modes. Yet, application of calibration methods using debriefing questions provided nearly identical values across modes. As such, neither mode appears to dominate from the perspective of providing more valid estimates of actual participation decisions. The selection of survey mode must be based on other criteria.Environmental Economics and Policy,
Enhanced Detection of Emotional Facial Expressions in Borderline Personality Disorder
Background: Borderline personality disorder (BPD) is commonly proposed to be
characterized by an enhanced sensitivity for emotional stimuli. In the present
study, we investigated whether BPD patients show a superior detection of
emotional facial expressions relative to healthy controls. The detection of
emotional information in the environment represents an important facet of
emotional sensitivity. Sampling and Methods: Twenty patients with BPD were
compared with 25 healthy controls. The participants were presented a rapid,
continuous stream of neutral and randomly inserted emotional facial
expressions and were asked to report the presentation of an emotional facial
stimulus after each trial. Availability of cognitive resources was manipulated
via two different task demands. Results: The participants with BPD performed
significantly better in the detection of positive and negative facial
expressions compared to the healthy controls. False alarm rates did not differ
significantly between the two groups. Conclusions: The BPD participants showed
an enhanced detection of emotional expressions that might be related to the
emotional disturbances they experience. In particular, we will discuss the
role of this superior emotion detection (in combination with previously
reported deficits in the labeling of emotional states) for the understanding
of emotional instability in BPD
The regional impact of Indonesia's fiscal policy on oil and gas: Options for reform
This paper analyzes the regional impact of Indonesia's fuel policy. It discusses how the sharing of oil and gas revenue and taxes on oil and gas between the center and the regions affect sub-national fiscal position and what the regional incidence of the fuel subsidies is. It also analyzes the regional impact of president's recent proposal to discontinue subsidizing vehicle fuel aswell as the proposal to eliminate the fuel subsidies altogether and shows how the regions are affected ty these suggestions
Existence of axially symmetric static solutions of the Einstein-Vlasov system
We prove the existence of static, asymptotically flat non-vacuum spacetimes
with axial symmetry where the matter is modeled as a collisionless gas. The
axially symmetric solutions of the resulting Einstein-Vlasov system are
obtained via the implicit function theorem by perturbing off a suitable
spherically symmetric steady state of the Vlasov-Poisson system.Comment: 32 page
Pion damping width from SU(2) x SU(2) NJL model
Within the framework of the NJL model, we investigate the modification of the
pion damping width in a hot pion gas for temperatures ranging from 0 to 180
MeV. The pion is found to broaden noticeably at T > 60 MeV. Near the chiral
phase transition T ~ 180 MeV, the pion width is saturated and amounts to 70
MeV. The main contribution to the width comes from pion-pion collisions. Other
contributions are found negligibly small.Comment: LaTeX2e, 13 pages, 2 figure
Scalar correlations in a quark plasma and low mass dilepton production
We investigate possible consequences of resonant scalar interactions for
dilepton production from a quark plasma at the chiral phase transition. It is
found that this production mechanism is strongly suppressed compared to the
Born process and has no significance for present experiments.Comment: 7 pages revtex, 2 ps figure
Three Types of Cooling Superfluid Neutron Stars: Theory and Observations
Cooling of neutron stars (NSs) with the cores composed of neutrons, protons,
and electrons is simulated assuming S pairing of neutrons in the NS
crust, and also S pairing of protons and weak P pairing of
neutrons in the NS core, and using realistic density profiles of the superfluid
critical temperatures . The theoretical cooling models of
isolated middle-aged NSs can be divided into three main types. (I) {\it
Low-mass}, {\it slowly cooling} NSs where the direct Urca process of neutrino
emission is either forbidden or almost fully suppressed by the proton
superfluidity. (II) {\it Medium-mass} NSs which show {\it moderate} cooling via
the direct Urca process suppressed by the proton superfluidity. (III) {\it
Massive} NSs which show {\it fast} cooling via the direct Urca process weakly
suppressed by superfluidity. Confronting the theory with observations we treat
RX J0822--43, PSR 1055--52 and RX J1856--3754 as slowly cooling NSs. To explain
these sufficiently warm sources we need a density profile in
the crust with a rather high and flat maximum and sharp wings. We treat 1E
1207--52, RX J0002+62, PSR 0656+14, Vela, and Geminga as moderately cooling
NSs. We can determine their masses for a given model of proton superfluidity,
, and the equation of state in the NS core. No rapidly
cooling NS has been observed so far.Comment: 12 pages, 10 figures, Astron. Astrophys., submitte
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