16,350 research outputs found
Phase Coexistence in Driven One Dimensional Transport
We study a one-dimensional totally asymmetric exclusion process with random
particle attachments and detachments in the bulk. The resulting dynamics leads
to unexpected stationary regimes for large but finite systems. Such regimes are
characterized by a phase coexistence of low and high density regions separated
by domain walls. We use a mean-field approach to interpret the numerical
results obtained by Monte-Carlo simulations and we predict the phase diagram of
this non-conserved dynamics in the thermodynamic limit.Comment: 4 pages, 3 figures. Accepted for publication on Phys. Rev. Let
Membrane paradigm and entropy of black holes in the Euclidean action approach
The membrane paradigm approach to black holes fixes in the vicinity of the
event horizon a fictitious surface, the stretched horizon, so that the
spacetime outside remains unchanged and the spacetime inside is vacuum. Using
this powerful method, several black hole properties have been found and
settled, such as the horizon's viscosity, electrical conductivity, resistivity,
as well as other properties. On the other hand the Euclidean action approach to
black hole spacetimes has been very fruitful in understanding black hole
entropy. Combining both the Euclidean action and membrane paradigm approaches a
direct derivation of the black hole entropy is given. In the derivation it is
considered that the only fields present are the gravitational and matter
fields, with no electric field.Comment: 13 page
Renormalised four-point coupling constant in the three-dimensional O(N) model with N=0
We simulate self-avoiding walks on a cubic lattice and determine the second
virial coefficient for walks of different lengths. This allows us to determine
the critical value of the renormalized four-point coupling constant in the
three-dimensional N-vector universality class for N=0. We obtain g* =
1.4005(5), where g is normalized so that the three-dimensional
field-theoretical beta-function behaves as \beta(g) = - g + g^2 for small g. As
a byproduct, we also obtain precise estimates of the interpenetration ratio
Psi*, Psi* = 0.24685(11), and of the exponent \nu, \nu = 0.5876(2).Comment: 16 page
DC-transport properties of ferromagnetic (Ga,Mn)As semiconductors
We study the dc transport properties of (Ga,Mn)As diluted magnetic
semiconductors with Mn concentration varying from 1.5% to 8%. Both diagonal and
Hall components of the conductivity tensor are strongly sensitive to the
magnetic state of these semiconductors. Transport data obtained at low
temperatures are discussed theoretically within a model of band-hole
quasiparticles with a finite spectral width due to elastic scattering from Mn
and compensating defects. The theoretical results are in good agreement with
measured anomalous Hall effect and anisotropic longitudinal magnetoresistance
data. This quantitative understanding of dc magneto-transport effects in
(Ga,Mn)As is unparalleled in itinerant ferromagnetic systems.Comment: 3 pages, 3 figure
Jack polynomials with prescribed symmetry and hole propagator of spin Calogero-Sutherland model
We study the hole propagator of the Calogero-Sutherland model with SU(2)
internal symmetry. We obtain the exact expression for arbitrary non-negative
integer coupling parameter and prove the conjecture proposed by one of
the authors. Our method is based on the theory of the Jack polynomials with a
prescribed symmetry.Comment: 12 pages, REVTEX, 1 eps figur
Edge spin accumulation in semiconductor two-dimensional hole gases
The controlled generation of localized spin densities is a key enabler of
semiconductor spintronics In this work, we study spin Hall effect induced edge
spin accumulation in a two-dimensional hole gas with strong spin orbit
interactions. We argue that it is an intrinsic property, in the sense that it
is independent of the strength of disorder scattering. We show numerically that
the spin polarization near the edge induced by this mechanism can be large, and
that it becomes larger and more strongly localized as the spin-orbit coupling
strength increases, and is independent of the width of the conducting strip
once this exceeds the elastic scattering mean-free-path. Our experiments in
two-dimensional hole gas microdevices confirm this remarkable spin Hall effect
phenomenology. Achieving comparable levels of spin polarization by external
magnetic fields would require laboratory equipment whose physical dimensions
and operating electrical currents are million times larger than those of our
spin Hall effect devices.Comment: 6 pages, 5 figure
Weight Vectors of the Basic A_1^(1)-Module and the Littlewood-Richardson Rule
The basic representation of \A is studied. The weight vectors are
represented in terms of Schur functions. A suitable base of any weight space is
given. Littlewood-Richardson rule appears in the linear relations among weight
vectors.Comment: February 1995, 7pages, Using AMS-Te
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Prevalence of pain flashbacks in post-traumatic stress disorder arising from exposure to multiple traumas or childhood traumatization
Background: Flashbacks are a form of multisensory memory that are experienced with a ‘happening in the present’ quality. Pain flashbacks are a re-experiencing of pain felt at the time of a traumatic event. It is unclear how common pain flashbacks are.
Aims: The current study was designed primarily to assess the prevalence of pain flashbacks in a sample of patients with post-traumatic stress disorder (PTSD).
Methods: We assessed the prevalence of pain flashbacks over a period of two years in patients (n = 166) referred to a psychological trauma service in the UK. Patients underwent a clinical screen for PTSD, and completed a self-report measure of pain flashbacks.
Results: Pain flashbacks were classified as present in 49% of a sample of complex trauma patients meeting criteria for PTSD. Pain flashbacks were positively associated with the extent of pain at the time of trauma.
Conclusions: Pain re-experiencing in PTSD, and its relative absence in non-clinical populations, supports an account of memory in which perceptual details can be re- experienced when memories have been encoded under conditions of extreme stress. It may be possible to conceptualize some cases of unexplained pain as pain flashbacks, or of having a trauma origin
Parafermionic algebras, their modules and cohomologies
We explore the Fock spaces of the parafermionic algebra introduced by H.S.
Green. Each parafermionic Fock space allows for a free minimal resolution by
graded modules of the graded 2-step nilpotent subalgebra of the parafermionic
creation operators. Such a free resolution is constructed with the help of a
classical Kostant's theorem computing Lie algebra cohomologies of the nilpotent
subalgebra with values in the parafermionic Fock space. The Euler-Poincar\'e
characteristics of the parafermionic Fock space free resolution yields some
interesting identities between Schur polynomials. Finally we briefly comment on
parabosonic and general parastatistics Fock spaces.Comment: 10 pages, talk presented at the International Workshop "Lie theory
and its applications in Physics" (17-23 June 2013, Varna, Bulgaria
Drag in paired electron-hole layers
We investigate transresistance effects in electron-hole double layer systems
with an excitonic condensate. Our theory is based on the use of a minimum
dissipation premise to fix the current carried by the condensate. We find that
the drag resistance jumps discontinuously at the condensation temperature and
diverges as the temperature approaches zero.Comment: 12 pages, 1 Figure, .eps file attache
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