3,150 research outputs found
Topologically Massive Gauge Theory: A Lorentzian Solution
We obtain a lorentzian solution for the topologically massive non-abelian
gauge theory on AdS space by means of a SU(1, 1) gauge transformation of the
previously found abelian solution. There exists a natural scale of length which
is determined by the inverse topological mass. The topological mass is
proportional to the square of the gauge coupling constant. In the topologically
massive electrodynamics the field strength locally determines the gauge
potential up to a closed 1-form via the (anti-)self-duality equation. We
introduce a transformation of the gauge potential using the dual field strength
which can be identified with an abelian gauge transformation. Then we present
the map from the AdS space to the pseudo-sphere including the topological mass.
This is the lorentzian analog of the Hopf map. This map yields a global
decomposition of the AdS space as a trivial circle bundle over the upper
portion of the pseudo-sphere which is the Hyperboloid model for the Lobachevski
geometry. This leads to a reduction of the abelian field equation onto the
pseudo-sphere using a global section of the solution on the AdS space. Then we
discuss the integration of the field equation using the Archimedes map from the
pseudo-sphere to the cylinder over the ideal Poincare circle. We also present a
brief discussion of the holonomy of the gauge potential and the dual-field
strength on the upper portion of the pseudo-sphere.Comment: 23 pages, 1 postscript figur
The prevalence of autistic traits in a homeless population
Anecdotal evidence suggests that autistic people experience an elevated risk of homelessness, but systematic empirical research on this topic is lacking. As a step towards filling this gap in knowledge, we conducted a preliminary investigation of the prevalence of Diagnostic and Statistical Manual of Mental Disorders (5th ed.) autism symptoms in a group of long-term homeless people. The entire caseload ( N = 106) of a UK homeless outreach team was screened (excluding individuals born outside of the United Kingdom or Republic of Ireland) using an in-depth, semi-structured interview with keyworkers, based on Diagnostic and Statistical Manual of Mental Disorders (5th ed.) diagnostic criteria. This showed adequate inter-rater reliability, as well as evidence of criterion and construct validity. Of the sample, 13 people (12.3%, 95% confidence interval (7.0, 20.4)) screened positive, meeting Diagnostic and Statistical Manual of Mental Disorders (5th ed.) autism criteria by keyworker report. A further nine people (8.5%, 95% confidence interval (4.5, 15.3)) were 'marginal', having autistic traits that were not quite sufficient to meet Diagnostic and Statistical Manual of Mental Disorders (5th ed.) criteria. Those with elevated autistic traits, compared to those without, tended to be more socially isolated and less likely to use substances. This study has provided initial evidence that autistic traits are over-represented among homeless people and that autistic homeless people may show a distinct pattern of characteristics and needs. Further investigation is required to build upon these provisional findings
The SoLid anti-neutrino detector's readout system
The SoLid collaboration have developed an intelligent readout system to
reduce their 3200 silicon photomultiplier detector's data rate by a factor of
10000 whilst maintaining high efficiency for storing data from anti-neutrino
interactions. The system employs an FPGA-level waveform characterisation to
trigger on neutron signals. Following a trigger, data from a space time region
of interest around the neutron will be read out using the IPbus protocol. In
these proceedings the design of the readout system is explained and results
showing the performance of a prototype version of the system are presented
Predicting pharmacy naloxone stocking and dispensing following a statewide standing order, Indiana 2016
BACKGROUND:
While naloxone, the overdose reversal medication, has been available for decades, factors associated with its availability through pharmacies remain unclear. Studies suggest that policy and pharmacist beliefs may impact availability. Indiana passed a standing order law for naloxone in 2015 to increase access to naloxone.
OBJECTIVE:
To identify factors associated with community pharmacy naloxone stocking and dispensing following the enactment of a statewide naloxone standing order.
METHODS:
A 2016 cross-sectional census of Indiana community pharmacists was conducted following a naloxone standing order. Community, pharmacy, and pharmacist characteristics, and pharmacist attitudes about naloxone dispensing, access, and perceptions of the standing order were measured. Modified Poisson and binary logistic regression models attempted to predict naloxone stocking and dispensing, respectively.
RESULTS:
Over half (58.1%) of pharmacies stocked naloxone, yet 23.6% of pharmacists dispensed it. Most (72.5%) pharmacists believed the standing order would increase naloxone stocking, and 66.5% believed it would increase dispensing. Chain pharmacies were 3.2 times as likely to stock naloxone. Naloxone stocking was 1.6 times as likely in pharmacies with more than one full-time pharmacist. Pharmacies where pharmacists received naloxone continuing education in the past two years were 1.3 times as likely to stock naloxone. The attempted dispensing model yielded no improvement over the constant-only model.
CONCLUSIONS:
Pharmacies with larger capacity took advantage of the naloxone standing order. Predictors of pharmacist naloxone dispensing should continue to be explored to maximize naloxone access
Equivalence between different classical treatments of the O(N) nonlinear sigma model and their functional Schrodinger equations
In this work we derive the Hamiltonian formalism of the O(N) non-linear sigma
model in its original version as a second-class constrained field theory and
then as a first-class constrained field theory. We treat the model as a
second-class constrained field theory by two different methods: the
unconstrained and the Dirac second-class formalisms. We show that the
Hamiltonians for all these versions of the model are equivalent. Then, for a
particular factor-ordering choice, we write the functional Schrodinger equation
for each derived Hamiltonian. We show that they are all identical which
justifies our factor-ordering choice and opens the way for a future
quantization of the model via the functional Schrodinger representation.Comment: Revtex version, 17 pages, substantial change
The ultraluminous X-ray source NGC 1313 X-2 - Its optical counterpart and environment
NGC 1313 X-2 is one of the brightest ultraluminous X-ray sources in the sky,
at both X-ray and optical wavelengths; therefore, quite a few studies of
available ESO VLT and HST data have appeared in the literature. Here, we
present our analysis of VLT/FORS1 and HST/ACS photometric data, confirming the
identification of the B ~ 23 mag blue optical counterpart. We show that the
system is part of a poor cluster with an age of 20 Myr, leading to an upper
mass limit of some 12 M_sun for the mass donor. We attribute the different
results with respect to earlier studies to the use of isochrones in the F435W
and F555W HST/ACS photometric system that appear to be incompatible with the
corresponding Johnson B and V isochrones. The counterpart exhibits significant
photometric variability of about 0.2 mag amplitude, both between the two HST
observations and during the one month of monitoring with the VLT. This includes
variability within one night and suggests that the light is dominated by the
accretion disk in the system and not by the mass donor.Comment: 13 pages, 11 figures. Accepted for publication in Astronomy &
Astrophysic
Quantum gravitational optics: the induced phase
The geometrical approximation of the extended Maxwell equation in curved
spacetime incorporating interactions induced by the vacuum polarization effects
is considered. Taking into account these QED interactions and employing the
analogy between eikonal equation in geometrical optics and Hamilton-Jacobi
equation for the particle motion, we study the phase structure of the modified
theory. There is a complicated, local induced phase which is believed to be
responsible for the modification of the classical picture of light ray. The
main features of QGO could be obtained through the study of this induced phase.
We discuss initial principles in conventional and modified geometrical optics
and compare the results.Comment: 10 pages, REVTex forma
Quantum Electrodynamics and the Origins of the Exchange, Dipole-Dipole, and Dzyaloshinsky-Moriya Interactions in Itinerant Fermion Systems
It is shown how the exchange interaction, the dipole-dipole interaction, and
the Dzyaloshinsky-Moriya interaction between electronic spin-density
fluctuations emerge naturally from a field-theoretic framework that couples
electrons to the fluctuating electromagnetic potential. Semi-quantitative
estimates are given to determine when the dipole-dipole interaction, which is
often neglected, needs to be considered, and various applications are
discussed, with an emphasis on weak ferromagnets and on helimagnets.Comment: 12pp, 3 fig
The Peculiar Rotation Curve of NGC 157
We present the results of a new HI, optical, and H-alpha interferometric
study of the nearby spiral galaxy NGC 157. Our combined C- and D-array
observations with the VLA show a large-scale, ring-like structure in the
neutral hydrogen underlying the optical disk, together with an extended, low
surface density component going out to nearly twice the Holmberg radius.
Beginning just inside the edge of the star-forming disk, the line of nodes in
the gas disk commences a 60 degree warp, while at the same time, the rotation
velocity drops by almost half its peak value of 200 km/s, before leveling off
again in the outer parts. While a flat rotation curve in NGC 157 cannot be
ruled out, supportive evidence for an abrupt decline comes from the ionised gas
kinematics, the optical surface photometry, and the global HI profile. A
standard `maximum-disk' mass model predicts comparable amounts of dark and
luminous matter within NGC 157. Alternatively, a model employing a disk
truncated at 2 disk scale lengths could equally well account for the unusual
form of the rotation curve in NGC 157.Comment: 26 pages, 15 figures, LaTeX, uses mn-1.4.sty. Accepted for
publication in MNRA
Non-Markovian entanglement dynamics of quantum continuous variable systems in thermal environments
We study two continuous variable systems (or two harmonic oscillators) and
investigate their entanglement evolution under the influence of non-Markovian
thermal environments. The continuous variable systems could be two modes of
electromagnetic fields or two nanomechanical oscillators in the quantum domain.
We use quantum open system method to derive the non-Markovian master equations
of the reduced density matrix for two different but related models of the
continuous variable systems. The two models both consist of two interacting
harmonic oscillators. In model A, each of the two oscillators is coupled to its
own independent thermal reservoir, while in model B the two oscillators are
coupled to a common reservoir. To quantify the degrees of entanglement for the
bipartite continuous variable systems in Gaussian states, logarithmic
negativity is used. We find that the dynamics of the quantum entanglement is
sensitive to the initial states, the oscillator-oscillator interaction, the
oscillator-environment interaction and the coupling to a common bath or to
different, independent baths.Comment: 10 two-column pages, 8 figures, to appear in Phys. Rev.
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