783 research outputs found
COVID-19 and Opioid Use in Appalachian Kentucky: Challenges and Silver Linings
Appalachian Kentucky is currently fighting two public health emergencies â COVID-19 and the opioid epidemic â leaving the area strapped for resources to care for these ongoing crises. During this time, people who use opioids (PWUO) have increased vulnerability to fatal overdoses and drug-related harms (e.g., HIV). Disruption of already limited services posed by COVID-19 could have an especially detrimental impact on the health of PWUO. Though the COVID-19 pandemic is jeopardizing hard-won progress in fighting the opioid epidemic, innovations in state policy and service delivery brought about by the pandemic may improve the health of PWUO long-term if they are retained
Renormalization Group Equation and QCD Coupling Constant in the Presence of SU(3) Chromo-Electric Field
We solve renormalization group equation in QCD in the presence of SU(3)
constant chromo-electric field E^a with arbitrary color index a=1,2,...8 and
find that the QCD coupling constant \alpha_s depends on two independent
casimir/gauge invariants C_1=[E^aE^a] and C_2=[d_{abc}E^aE^bE^c]^2 instead of
one gauge invariant C_1=[E^aE^a]. The \beta function is derived from the
one-loop effective action. This coupling constant may be useful to study hadron
formation from color flux tubes/strings at high energy colliders and to study
quark-gluon plasma formation at RHIC and LHC.Comment: 13 pages latex, 4 eps figs, Eur. Phys. J.
Schwinger Mechanism for Gluon Pair Production in the Presence of Arbitrary Time Dependent Chromo-Electric Field
We study Schwinger mechanism for gluon pair production in the presence of
arbitrary time-dependent chromo-electric background field with
arbitrary color index =1,2,...8 in SU(3) by directly evaluating the path
integral. We obtain an exact expression for the probability of non-perturbative
gluon pair production per unit time per unit volume and per unit transverse
momentum from arbitrary . We show that the
tadpole (or single gluon) effective action does not contribute to the
non-perturbative gluon pair production rate . We find
that the exact result for non-perturbative gluon pair production is independent
of all the time derivatives where
and has the same functional dependence on two casimir invariants
and as the constant
chromo-electric field result with the replacement: . This
result may be relevant to study the production of a non-perturbative
quark-gluon plasma at RHIC and LHC.Comment: 13 pages latex, Published in European Physical Journal
Influence of grain-refiner addition on the morphology of fe-bearing intermetallics in a semi-solid processed Al-Mg-Si alloy
© The Minerals, Metals & Materials Society and ASM International 2013The three-dimensional morphologies of the Fe-bearing intermetallics in a semisolid-processed Al-Mg-Si alloy were examined after extracting the intermetallics. α -AlFeSi and ÎČ-AlFeSi are the major Fe-bearing intermetallics. Addition of Al-Ti-B grain refiner typically promotes ÎČ-AlFeSi formation. ÎČ-AlFeSi was observed with a flat, plate-like morphology with angular edges in the alloy with and without grain refiner, whereas α -AlFeSi was observed as "flower"-like morphology in the alloy with grain refiner. © 2013 The Minerals, Metals & Materials Society and ASM International
Confidentiality considerations for use of social-spatial data on the social determinants of health: Sexual and reproductive health case study
Understanding whether and how the places where people live, work, and play are associated with health behaviors and health is essential to understanding the social determinants of health. However, social-spatial data which link a person and their attributes to a geographic location (e.g., home address) create potential confidentiality risks. Despite the growing body of literature describing approaches to protect individual confidentiality when utilizing social-spatial data, peer-reviewed manuscripts displaying identifiable individual point data or quasi-identifiers (attributes associated with the individual or disease that narrow identification) in maps persist, suggesting that knowledge has not been effectively translated into public health research practices. Using sexual and reproductive health as a case study, we explore the extent to which maps appearing in recent peer-reviewed publications risk participant confidentiality. Our scoping review of sexual and reproductive health literature published and indexed in PubMed between January 1, 2013 and September 1, 2015 identified 45 manuscripts displaying participant data in maps as points or small-population geographic units, spanning 26 journals and representing studies conducted in 20 countries. Notably, 56% (13/23) of publications presenting point data on maps either did not describe approaches used to mask data or masked data inadequately. Furthermore, 18% (4/22) of publications displaying data using small-population geographic units included at least two quasi-identifiers. These findings highlight the need for heightened education for researchers, reviewers, and editorial teams. We aim to provide readers with a primer on key confidentiality considerations when utilizing linked social-spatial data for visualizing results. Given the widespread availability of place-based data and the ease of creating maps, it is critically important to raise awareness on when social-spatial data constitute protected health information, best practices for masking geographic identifiers, and methods of balancing disclosure risk and scientific utility. We conclude with recommendations to support the preservation of confidentiality when disseminating results
Dynamics of coupled bosonic systems with applications to preheating
Coupled, multi-field models of inflation can provide several attractive
features unavailable in the case of a single inflaton field. These models have
a rich dynamical structure resulting from the interaction of the fields and
their associated fluctuations. We present a formalism to study the
nonequilibrium dynamics of coupled scalar fields. This formalism solves the
problem of renormalizing interacting models in a transparent way using
dimensional regularization. The evolution is generated by a renormalized
effective Lagrangian which incorporates the dynamics of the mean fields and
their associated fluctuations at one-loop order. We apply our method to two
problems of physical interest: (i) a simple two-field model which exemplifies
applications to reheating in inflation, and (ii) a supersymmetric hybrid
inflation model. This second case is interesting because inflation terminates
via a smooth phase transition which gives rise to a spinodal instability in one
of the fields. We study the evolution of the zero mode of the fields and the
energy density transfer to the fluctuations from the mean fields. We conclude
that back reaction effects can be significant over a wide parameter range. In
particular for the supersymmetric hybrid model we find that particle production
can be suppressed due to these effects.Comment: 23 pages, 16 eps-figures, minor changes in the text, references
added, accepted for publication in PR
Out-of-equilibrium evolution of scalar fields in FRW cosmology: renormalization and numerical simulations
We present a renormalized computational framework for the evolution of a
self-interacting scalar field (inflaton) and its quantum fluctuations in an FRW
background geometry. We include a coupling of the field to the Ricci scalar
with a general coupling parameter . We take into account the classical and
quantum back reactions, i.e., we consider the the dynamical evolution of the
cosmic scale factor. We perform, in the one-loop and in the large-N
approximation, the renormalization of the equation of motion for the inflaton
field, and of its energy momentum tensor. Our formalism is based on a
perturbative expansion for the mode functions, and uses dimensional
regularization. The renormalization procedure is manifestly covariant and the
counter terms are independent of the initial state. Some shortcomings in the
renormalization of the energy-momentum tensor in an earlier publication are
corrected. We avoid the occurence of initial singularities by constructing a
suitable class of initial states. The formalism is implemented numerically and
we present some results for the evolution in the post-inflationary preheating
era.Comment: 44 pages, uses latexsym, 6 pages with 11 figures in a .ps fil
Public Housing Relocations and Partnership Dynamics in Areas With High Prevalences of Sexually Transmitted Infections
We investigated the implications of one structural interventionâpublic housing relocationsâfor partnership dynamics among individuals living areas with high sexually transmitted infection (STI) prevalence. High-prevalence areas fuel STI endemicity and are perpetuated by spatially assortative partnerships
Nonequilibrium evolution in scalar O(N) models with spontaneous symmetry breaking
We consider the out-of-equilibrium evolution of a classical condensate field
and its quantum fluctuations for a scalar O(N) model with spontaneously broken
symmetry. In contrast to previous studies we do not consider the large N limit,
but the case of finite N, including N=1, i.e., plain theory.
The instabilities encountered in the one-loop approximation are prevented, as
in the large-N limit, by back reaction of the fluctuations on themselves, or,
equivalently, by including a resummation of bubble diagrams.
For this resummation and its renormalization we use formulations developed
recently based on the effective action formalism of Cornwall, Jackiw and
Tomboulis. The formulation of renormalized equations for finite N derived here
represents a useful tool for simulations with realistic models. Here we
concentrate on the phase structure of such models. We observe the transition
between the spontaneously broken and the symmetric phase at low and high energy
densities, respectively. This shows that the typical structures expected in
thermal equilibrium are encountered in nonequilibrium dynamics even at early
times, i.e., before an efficient rescattering can lead to thermalization.Comment: 31 pages, 19 Figures, LaTeX; extended discussion on the basis of:
fluctuations, eff. potential, correlations, analytic calculation of
parametric resonance for "pion"_and_ "sigma" field
- âŠ