636 research outputs found
Black Hole Remnants and the Information Puzzle
Magnetically charged dilatonic black holes have a perturbatively infinite
ground state degeneracy associated with an infinite volume throat region of the
geometry. A simple argument based on causality is given that these states do
not have a description as ordinary massive particles in a low-energy effective
field theory. Pair production of magnetic black holes in a weak magnetic field
is estimated in a weakly-coupled semiclassical expansion about an instanton and
found to be finite, despite the infinite degeneracy of states. This suggests
that these states may store the information apparently lost in black hole
scattering processes.Comment: 16 pages, revision has 5 figures uuencode
Quantum Black Holes
Static solutions of large- quantum dilaton gravity in dimensions are
analyzed and found to exhibit some unusual behavior. As expected from previous
work, infinite-mass solutions are found describing a black hole in equilibrium
with a bath of Hawking radiation. Surprisingly, the finite mass solutions are
found to approach zero coupling both at the horizon and spatial infinity, with
a ``bounce'' off of strong coupling in between. Several new zero mass solutions
-- candidate quantum vacua -- are also described.Comment: 14 pages + 6 figure
Dynamics of Extremal Black Holes
Particle scattering and radiation by a magnetically charged, dilatonic black
hole is investigated near the extremal limit at which the mass is a constant
times the charge. Near this limit a neighborhood of the horizon of the black
hole is closely approximated by a trivial product of a two-dimensional black
hole with a sphere. This is shown to imply that the scattering of
long-wavelength particles can be described by a (previously analyzed)
two-dimensional effective field theory, and is related to the
formation/evaporation of two-dimensional black holes. The scattering proceeds
via particle capture followed by Hawking re-emission, and naively appears to
violate unitarity. However this conclusion can be altered when the effects of
backreaction are included. Particle-hole scattering is discussed in the light
of a recent analysis of the two-dimensional backreaction problem. It is argued
that the quantum mechanical possibility of scattering off of extremal black
holes implies the potential existence of additional quantum numbers - referred
to as ``quantum whiskers'' - characterizing the black hole.Comment: 31 page
Reduced dimensionality spin-orbit dynamics of CH3 + HCl reversible arrow CH4 Cl on ab initio surfaces
A reduced dimensionality quantum scattering method is extended to the study of spin-orbit nonadiabatic transitions in the CH3 + HCl reversible arrow CH4 + Cl(P-2(J)) reaction. Three two-dimensional potential energy surfaces are developed by fitting a 29 parameter double-Morse function to CCSD(T)/IB//MP2/cc-pV(T+d)Z-dk ab initio data; interaction between surfaces is described by geometry-dependent spin-orbit coupling functions fit to MCSCF/cc-pV(T+d)Z-dk ab initio data. Spectator modes are treated adiabatically via inclusion of curvilinear projected frequencies. The total scattering wave function is expanded in a vibronic basis set and close-coupled equations are solved via R-matrix propagation. Ground state thermal rate constants for forward and reverse reactions agree well with experiment. Multi-surface reaction probabilities, integral cross sections, and initial-state selected branching ratios all highlight the importance of vibrational energy in mediating nonadiabatic transition. Electronically excited state dynamics are seen to play a small but significant role as consistent with experimental conclusions. (C) 2011 American Institute of Physics. [doi:10.1063/1.3592732
The Matrix Theory S-Matrix
The technology required for eikonal scattering amplitude calculations in
Matrix theory is developed. Using the entire supersymmetric completion of the
v^4/r^7 Matrix theory potential we compute the graviton-graviton scattering
amplitude and find agreement with eleven dimensional supergravity at tree
level.Comment: 10 pages, RevTeX, no figure
Quantum Theories of Dilaton Gravity
Quantization of two-dimensional dilaton gravity coupled to conformal matter
is investigated. Working in conformal gauge about a fixed background metric,
the theory may be viewed as a sigma model whose target space is parameterized
by the dilaton and conformal factor . A precise connection is
given between the constraint that the theory be independent of the background
metric and conformal invariance of the resulting sigma model. Although the
action is renormalizable, new coupling constants must be specified at each
order in perturbation theory in order to determine the quantum theory. These
constants may be viewed as initial data for the beta function equations. It is
argued that not all choices of this data correspond to physically sensible
theories of gravity, and physically motivated constraints on the data are
discussed. In particular a recently constructed subclass of initial data which
reduces the full quantum theory to a soluble Liouville-like theory has energies
unbounded from below and thus is unphysical. Possibilities for modifying this
construction so as to avoid this difficulty are briefly discussed.Comment: 20 pages (Major additions made, including 5 pages on the relation
between conformal invariance and background independence.
S-Wave Scattering of Charged Fermions by a Magnetic Black Hole
We argue that, classically, -wave electrons incident on a magnetically
charged black hole are swallowed with probability one: the reflection
coefficient vanishes. However, quantum effects can lead to both electromagnetic
and gravitational backscattering. We show that, for the case of extremal,
magnetically charged, dilatonic black holes and a single flavor of low-energy
charged particles, this backscattering is described by a perturbatively
computable and unitary -matrix, and that the Hawking radiation in these
modes is suppressed near extremality. The interesting and much more difficult
case of several flavors is also discussed.Comment: 9p
The Role of Discrete Emotions in Job Satisfaction: A Meta-Analysis
[Summary] The relationship between emotions and job satisfaction is widely acknowledged via affective events theory (AET). Despite its widespread use, AET was not designed to address why specific emotions might differentially relate to job satisfaction. We utilize appraisal theory of emotion to refine AET and provide this nuanced theorizing. We meta‐analytically test our ideas with 235 samples across 99 883 individuals and 22 600 intra‐individual episodes. We test two approaches—specific emotion experiences (16 discrete emotions) versus general emotion experiences (positive or negative emotions)—and present empirical evidence of their similarities and differences with job satisfaction. Our findings suggest that specific emotions with circumstance‐agency appraisals (e.g., depression and happiness) have the strongest associations with job satisfaction compared to emotions with self‐ and other‐agency appraisals and general emotion experiences. However, more variability is observed for negative emotions and job satisfaction compared to positive emotions. Further, we address and even challenge influential critiques of emotions and job satisfaction via a meta‐analytic test of five moderators—emotion intensity versus frequency, target of emotion, job satisfaction measure, level of analysis, and time referent for emotion and job satisfaction recall. In sum, we advance academic and practitioner understanding of the relationship between emotions and job satisfaction
Dual-Functional Phosphorene Nanocomposite Membranes for the Treatment of Perfluorinated Water: An Investigation of Perfluorooctanoic Acid Removal via Filtration Combined with Ultraviolet Irradiation or Oxygenation
Nanomaterials with tunable properties show promise because of their size-dependent electronic structure and controllable physical properties. The purpose of this research was to develop and validate environmentally safe nanomaterial-based approach for treatment of drinking water including removal and degradation of per- and polyfluorinated chemicals (PFAS). PFAS are surfactant chemicals with broad uses that are now recognized as contaminants with a significant risk to human health. They are commonly used in household and industrial products. They are extremely persistent in the environment because they possess both hydrophobic fluorine-saturated carbon chains and hydrophilic functional groups, along with being oleophobic. Traditional drinking water treatment technologies are usually ineffective for the removal of PFAS from contaminated waters, because they are normally present in exiguous concentrations and have unique properties that make them persistent. Therefore, there is a critical need for safe and efficient remediation methods for PFAS, particularly in drinking water. The proposed novel approach has also a potential application for decreasing PFAS background levels in analytical systems. In this study, nanocomposite membranes composed of sulfonated poly ether ether ketone (SPEEK) and two-dimensional phosphorene were fabricated, and they obtained on average 99% rejection of perfluorooctanoic acid (PFOA) alongside with a 99% removal from the PFOA that accumulated on surface of the membrane. The removal of PFOA accumulated on the membrane surface achieved 99% after the membranes were treated with ultraviolet (UV) photolysis and liquid aerobic oxidation
Differential gene expression between fall- and spring-run Chinook salmon assessed by long serial analysis of gene expression
Author Posting. © American Fisheries Society, 2008. This article is posted here by permission of American Fisheries Society for personal use, not for redistribution. The definitive version was published in Transactions of the American Fisheries Society 137 (2008): 1378–1388, doi:10.1577/T07-222.1.Of all Pacific salmonids, Chinook salmon Oncorhynchus tshawytscha display the greatest variability in return times to freshwater. The molecular mechanisms of these differential return times have not been well described. Current methods, such as long serial analysis of gene expression (LongSAGE) and microarrays, allow gene expression to be analyzed for thousands of genes simultaneously. To investigate whether differential gene expression is observed between fall- and spring-run Chinook salmon from California's Central Valley, LongSAGE libraries were constructed. Three libraries containing between 25,512 and 29,372 sequenced tags (21 base pairs/tag) were generated using messenger RNA from the brains of adult Chinook salmon returning in fall and spring and from one ocean-caught Chinook salmon. Tags were annotated to genes using complementary DNA libraries from Atlantic salmon Salmo salar and rainbow trout O. mykiss. Differentially expressed genes, as estimated by differences in the number of sequence tags, were found in all pairwise comparisons of libraries (freshwater versus saltwater = 40 genes; fall versus spring = 11 genes; and spawning versus nonspawning = 51 genes). The gene for ependymin, an extracellular glycoprotein involved in behavioral plasticity in fish, exhibited the most differential expression among the three groupings. Reverse transcription polymerase chain reaction analysis verified the differential expression of ependymin between the fall- and spring-run samples. These LongSAGE libraries, the first reported for Chinook salmon, provide a window of the transcriptional changes during Chinook salmon return migration to freshwater and spawning and increase the amount of expressed sequence data.This work was supported with a grant from the
California Department of Water Resources awarded to
M.A.B.; J.C.B. received additional funding from the
North Umpqua Foundation, Roseburg, Oregon
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