8,654 research outputs found
The negative acute phase response of serum transthyretin following Streptococcus suis infection in the pig
Peer reviewedPublisher PD
SU(2)-invariant spin-1/2 Hamiltonians with RVB and other valence bond phases
We construct a family of rotationally invariant, local, S=1/2 Klein
Hamiltonians on various lattices that exhibit ground state manifolds spanned by
nearest-neighbor valence bond states. We show that with selected perturbations
such models can be driven into phases modeled by well understood quantum dimer
models on the corresponding lattices. Specifically, we show that the
perturbation procedure is arbitrarily well controlled by a new parameter which
is the extent of decoration of the reference lattice. This strategy leads to
Hamiltonians that exhibit i) RVB phases in two dimensions, ii) U(1) RVB
phases with a gapless ``photon'' in three dimensions, and iii) a Cantor
deconfined region in two dimensions. We also construct two models on the
pyrochlore lattice, one model exhibiting a RVB phase and the other a U(1)
RVB phase.Comment: 16 pages, 15 figures; 1 figure and some references added; some minor
typos fixe
Integrable versus Non-Integrable Spin Chain Impurity Models
Recent renormalization group studies of impurities in spin-1/2 chains appear
to be inconsistent with Bethe ansatz results for a special integrable model. We
study this system in more detail around the integrable point in parameter space
and argue that this integrable impurity model corresponds to a non-generic
multi-critical point. Using previous results on impurities in half-integer spin
chains, a consistent renormalization group flow and phase diagram is proposed.Comment: 20 pages 11 figures obtainable from authors, REVTEX 3.
Evidence from Identified Particles for Active Quark and Gluon Degrees of Freedom
Measurements of intermediate pT (1.5 < pT < 5.0 GeV/c) identified particle
distributions in heavy ion collisions at SPS and RHIC energies display striking
dependencies on the number of constituent quarks in the corresponding hadron.
One finds that elliptic flow at intermediate pT follows a constituent quark
scaling law as predicted by models of hadron formation through coalescence. In
addition, baryon production is also found to increase with event multiplicity
much faster than meson production. The rate of increase is similar for all
baryons, and seemingly independent of mass. This indicates that the number of
constituent quarks determines the multiplicity dependence of identified hadron
production at intermediate pT. We review these measurements and interpret the
experimental findings.Comment: 8 pages, 5 figures, proceedings for SQM2006 conference in Los Angele
The Stellar Content of Obscured Galactic Giant HII Regions V: G333.1--0.4
We present high angular resolution near--infrared images of the obscured
Galactic Giant HII (GHII) region G333.1--0.4 in which we detect an OB star
cluster. For G333.1--0.4, we find OB stars and other massive objects in very
early evolutionary stages, possibly still accreting. We obtained --band
spectra of three stars; two show O type photospheric features, while the third
has no photospheric features but does show CO 2.3 m band--head emission.
This object is at least as hot as an early B type star based on its intrinsic
luminosity and is surrounded by a circumstellar disc/envelope which produces
near infrared excess emission. A number of other relatively bright cluster
members also display excess emission in the --band, indicative of
disks/envelopes around young massive stars. Based upon the O star photometry
and spectroscopy, the distance to the cluster is 2.6 0.4 kpc, similar to
a recently derived kinematic (near side) value. The slope of the --band
luminosity function is similar to those found in other young clusters. The mass
function slope is more uncertain, and we find - for stars with M M where the upper an lower limits are
calculated independently for different assumptions regarding the excess
emission of the individual massive stars. The number of Lyman continuum photons
derived from the contribution of all massive stars in the cluster is 0.2
. The
integrated cluster mass is 1.0
.Comment: 31 pages, including 12 figures and 3 tables. Accepted for publication
in the A
Higher Flow Harmonics in Heavy Ion Collisions from STAR
We report STAR measurements relating to higher flow harmonics including the
centrality dependence of two- and four-particle cumulants for harmonics 1 to 6.
Two-particle correlation functions vs. \Delta\eta and \Delta\phi are presented
for pT and number correlations. We find the power spectra (Fourier Transforms
of the correlation functions) for central collisions drop quickly for higher
harmonics. The \Delta\eta dependence of v3{2}2 and the pT and centrality
dependence of v2 and v3 are studied. Trends are conistent with expectations
from models including hot-spots in the initial energy density and an expansion
phase. We also present v3 and v2{2}2 - v2{4}2 vs. \surdsNN .Comment: 8 pages. Conference proceedings for Quark Matter 201
Teleportation of continuous quantum variables
A particularly startling discovery by Bennett et al. is the possibility for teleportation of a quantum state, whereby an unknown state of a spin-1/2 particle is transported by Alice from a sending station to Bob at a receiving terminal by conveying 2 bits of classical information. Beyond the context of dichotomic variables, Vaidman has analyzed teleportation of the wave function of a one-dimensional particle in a beautiful variation of the original EPR paradox. Here we extend Vaidman's analysis to incorporate finite (nonsingular) degrees of correlation among the relevant particles
Tunable few electron quantum dots in InAs nanowires
Quantum dots realized in InAs are versatile systems to study the effect of
spin-orbit interaction on the spin coherence, as well as the possibility to
manipulate single spins using an electric field. We present transport
measurements on quantum dots realized in InAs nanowires. Lithographically
defined top-gates are used to locally deplete the nanowire and to form
tunneling barriers. By using three gates, we can form either single quantum
dots, or two quantum dots in series along the nanowire. Measurements of the
stability diagrams for both cases show that this method is suitable for
producing high quality quantum dots in InAs.Comment: 8 pages, 4 figure
Density Matrix Renormalization Group Study of One-Dimensional Acoustic Phonons
We study the application of the density matrix renormalization group (DMRG)
to systems with one-dimensional acoustic phonons. We show how the use of a
local oscillator basis circumvents the difficulties with the long-range
interactions generated in real space using the normal phonon basis. When
applied to a harmonic atomic chain, we find excellent agreement with the exact
solution even when using a modest number of oscillator and block states (a few
times ten). We discuss the use of this algorithm in more complex cases and
point out its value when other techniques are deficient.Comment: 12 pages. To be published in PRB rapid co
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