22,350 research outputs found
Implications and Policy Options of California's Reliance on Natural Gas
Examines existing and currently anticipated infrastructure, rising gas prices, and recurring supply problems, and looks at options to alleviate the problem. Part of a series of research reports that examines energy issues facing California
Calculated collision induced absorption spectrum for He-Ar
Calculation of collision induced absorption spectra for helium-argo
Reconstructing the direction of reactor antineutrinos via electron scattering in Gd-doped water Cherenkov detectors
The potential of elastic antineutrino-electron scattering in a Gd-doped water
Cherenkov detector to determine the direction of a nuclear reactor antineutrino
flux was investigated using the recently proposed WATCHMAN antineutrino
experiment as a baseline model. The expected scattering rate was determined
assuming a 13-km standoff from a 3.758-GWt light water nuclear reactor and the
detector response was modeled using a Geant4-based simulation package.
Background was estimated via independent simulations and by scaling published
measurements from similar detectors. Background contributions were estimated
for solar neutrinos, misidentified reactor-based inverse beta decay
interactions, cosmogenic radionuclides, water-borne radon, and gamma rays from
the photomultiplier tubes (PMTs), detector walls, and surrounding rock. We show
that with the use of low background PMTs and sufficient fiducialization,
water-borne radon and cosmogenic radionuclides pose the largest threats to
sensitivity. Directional sensitivity was then analyzed as a function of radon
contamination, detector depth, and detector size. The results provide a list of
experimental conditions that, if satisfied in practice, would enable
antineutrino directional reconstruction at 3 significance in large
Gd-doped water Cherenkov detectors with greater than 10-km standoff from a
nuclear reactor.Comment: 11 pages, 9 figure
Attention bias dynamics and symptom severity during and following CBT for social anxiety disorder
Objective: Threat-related attention bias figures prominently in contemporary accounts of the maintenance of anxiety disorders, yet longitudinal intervention research relating attention bias to anxiety symptom severity is limited. Capitalizing on recent advances in the conceptualization and measurement of attention bias, we aimed to examine the relation between attention bias, indexed using trial-level bias scores (TLBSs) to quantify temporal dynamics reflecting dysregulation of attentional processing of threat (as opposed to aggregated mean bias scores) and social anxiety symptom severity over the course of cognitive-behavioral therapy (CBT) and 1-month follow-up. Method: Adults with social anxiety disorder (N = 39) assigned to either yohimbine-or placebo-augmented CBT completed measures of attention bias and social anxiety symptom severity weekly throughout CBT (5 sessions) and at 1-week and 1-month posttreatment. Results: TLBSs of attention bias temporal dynamics showed stronger psychometric properties than mean aggregated scores and were highly interrelated, in line with within-subject temporal variability fluctuating in time between attentional overengagement and strategic avoidance from threat. Attention bias toward threat and temporal variability in attention bias (i.e., attentional dysregulation), but not attention bias away from threat, significantly reduced over the course of CBT. Cross-lag analyses revealed no evidence of a causal relation between reductions in attentional dysregulation leading to symptom severity reduction, or vice versa. Observed relations did not vary as a function of time. Conclusions: We found no evidence for attentional dysregulation as a causal mechanism for symptom reduction in CBT for social anxiety disorders. Implications for future research are discussed
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Single-shot optical conductivity measurement of dense aluminum plasmas
The optical conductivity of a dense femtosecond laser-heated aluminum plasma heated to 0.1-1.5 eV was measured using frequency-domain interferometry with chirped pulses, permitting simultaneous observation of optical probe reflectivity and probe pulse phase shift. Coupled with published models of bound-electron contributions to the conductivity, these two independent experimental data yielded a direct measurement of both real and imaginary components of the plasma conductivity.DOE National Nuclear Security Administration DE-FC52-03NA00156Physic
Deriving Boltzmann Equations from Kadanoff-Baym Equations in Curved Space-Time
To calculate the baryon asymmetry in the baryogenesis via leptogenesis
scenario one usually uses Boltzmann equations with transition amplitudes
computed in vacuum. However, the hot and dense medium and, potentially, the
expansion of the universe can affect the collision terms and hence the
generated asymmetry. In this paper we derive the Boltzmann equation in the
curved space-time from (first-principle) Kadanoff-Baym equations. As one
expects from general considerations, the derived equations are covariant
generalizations of the corresponding equations in Minkowski space-time. We find
that, after the necessary approximations have been performed, only the
left-hand side of the Boltzmann equation depends on the space-time metric. The
amplitudes in the collision term on the right--hand side are independent of the
metric, which justifies earlier calculations where this has been assumed
implicitly. At tree level, the matrix elements coincide with those computed in
vacuum. However, the loop contributions involve additional integrals over the
the distribution function.Comment: 14 pages, 5 figures, extended discussion of the constraint equations
and the solution for the spectral functio
Extending Feynman's Formalisms for Modelling Human Joint Action Coordination
The recently developed Life-Space-Foam approach to goal-directed human action
deals with individual actor dynamics. This paper applies the model to
characterize the dynamics of co-action by two or more actors. This dynamics is
modelled by: (i) a two-term joint action (including cognitive/motivatonal
potential and kinetic energy), and (ii) its associated adaptive path integral,
representing an infinite--dimensional neural network. Its feedback adaptation
loop has been derived from Bernstein's concepts of sensory corrections loop in
human motor control and Brooks' subsumption architectures in robotics.
Potential applications of the proposed model in human--robot interaction
research are discussed.
Keywords: Psycho--physics, human joint action, path integralsComment: 6 pages, Late
Neutral Pion Production in the Threshold Region
We give an overview of the physics motivation and evolution of the neutral
pion photoproduction measurements in the threshold region conducted in the A2
collaboration at MAMI. The latest two experiments have been performed with the
almost 4-pi Crystal Ball detector. The first was with a linearly polarized
photon beam and unpolarized liquid-hydrogen target. The data analysis is now
complete and the linearly polarized beam asymmetry along with differential
cross sections provide the most stringent test to date of the predictions of
Chiral Perturbation Theory and its energy region of convergence. More recently
a measurement was performed using both circularly polarized photons and a
transversely polarized butanol frozen-spin target, with the goal of extracting
both the target and beam-target asymmetries. From these we intend to extract
pi-N scattering sensitive information for the first time in photo-pion
reactions. This will be used to test isospin conservation and further test
dynamics of chiral symmetry breaking in QCD as calculated at low energies by
Chiral Perturbation Theory.Comment: 8 pages, 5 figures, submitted to EPJ Special Topics as part of the
proceedings of the Conclusive Symposium of Collaborative Research Centre 44
Real structured singular value synthesis using the scaled Popov criterion
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/77238/1/AIAA-21537-608.pd
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