998 research outputs found
Fermionic Vacuum Energy from a Nielsen-Olesen Vortex
We calculate the vacuum energy of a spinor field in the background of a
Nielsen-Olesen vortex. We use the method of representing the vacuum energy in
terms of the Jost function on the imaginary momentum axis. Renormalization is
carried out using the heat kernel expansion and zeta functional regularization.
With this method well convergent sums and integrals emerge which allow for an
efficient numerical calculation of the vacuum energy in the given case where
the background is not known analytically but only numerically. The vacuum
energy is calculated for several choices of the parameters and it turns out to
give small corrections to the classical energy.Comment: 22 pages, 6 figure
Barred Galaxies in the Coma Cluster
We use ACS data from the HST Treasury survey of the Coma cluster (z~0.02) to
study the properties of barred galaxies in the Coma core, the densest
environment in the nearby Universe. This study provides a complementary data
point for studies of barred galaxies as a function of redshift and environment.
From ~470 cluster members brighter than M_I = -11 mag, we select a sample of
46 disk galaxies (S0--Im) based on visual classification. The sample is
dominated by S0s for which we find an optical bar fraction of 47+/-11% through
ellipse fitting and visual inspection. Among the bars in the core of the Coma
cluster, we do not find any very large (a_bar > 2 kpc) bars. Comparison to
other studies reveals that while the optical bar fraction for S0s shows only a
modest variation across low-to-intermediate density environments (field to
intermediate-density clusters), it can be higher by up to a factor of ~2 in the
very high-density environment of the rich Coma cluster core.Comment: Proceedings of the Bash symposium, to appear in the Astronomical
Society of the Pacific Conference Series, eds. L. Stanford, L. Hao, Y. Mao,
J. Gree
Electromagnetic Casimir densities for a wedge with a coaxial cylindrical shell
Vacuum expectation values of the field square and the energy-momentum tensor
for the electromagnetic field are investigated for the geometry of a wedge with
a coaxal cylindrical boundary. All boundaries are assumed to be perfectly
conducting and both regions inside and outside the shell are considered. By
using the generalized Abel-Plana formula, the vacuum expectation values are
presented in the form of the sum of two terms. The first one corresponds to the
geometry of the wedge without the cylindrical shell and the second term is
induced by the presence of the shell. The vacuum energy density induced by the
shell is negative for the interior region and is positive for the exterior
region. The asymptotic behavior of the vacuum expectation values are
investigated in various limiting cases. It is shown that the vacuum forces
acting on the wedge sides due to the presence of the cylindrical boundary are
always attractive.Comment: 21 pages, 7 figure
Grain boundary pinning and glassy dynamics in stripe phases
We study numerically and analytically the coarsening of stripe phases in two
spatial dimensions, and show that transient configurations do not achieve long
ranged orientational order but rather evolve into glassy configurations with
very slow dynamics. In the absence of thermal fluctuations, defects such as
grain boundaries become pinned in an effective periodic potential that is
induced by the underlying periodicity of the stripe pattern itself. Pinning
arises without quenched disorder from the non-adiabatic coupling between the
slowly varying envelope of the order parameter around a defect, and its fast
variation over the stripe wavelength. The characteristic size of ordered
domains asymptotes to a finite value $R_g \sim \lambda_0\
\epsilon^{-1/2}\exp(|a|/\sqrt{\epsilon})\epsilon\ll 1\lambda_0a$ a constant of order unity. Random fluctuations allow defect motion to
resume until a new characteristic scale is reached, function of the intensity
of the fluctuations. We finally discuss the relationship between defect pinning
and the coarsening laws obtained in the intermediate time regime.Comment: 17 pages, 8 figures. Corrected version with one new figur
Safety and Immunogenicity of a Recombinant Adenovirus Serotype 35-Vectored HIV-1 Vaccine in Adenovirus Serotype 5 Seronegative and Seropositive Individuals.
BACKGROUND: Recombinant adenovirus serotype 5 (rAd5)-vectored HIV-1 vaccines have not prevented HIV-1 infection or disease and pre-existing Ad5 neutralizing antibodies may limit the clinical utility of Ad5 vectors globally. Using a rare Ad serotype vector, such as Ad35, may circumvent these issues, but there are few data on the safety and immunogenicity of rAd35 directly compared to rAd5 following human vaccination.
METHODS: HVTN 077 randomized 192 healthy, HIV-uninfected participants into one of four HIV-1 vaccine/placebo groups: rAd35/rAd5, DNA/rAd5, and DNA/rAd35 in Ad5-seronegative persons; and DNA/rAd35 in Ad5-seropositive persons. All vaccines encoded the HIV-1 EnvA antigen. Antibody and T-cell responses were measured 4 weeks post boost immunization.
RESULTS: All vaccines were generally well tolerated and similarly immunogenic. As compared to rAd5, rAd35 was equally potent in boosting HIV-1-specific humoral and cellular immunity and responses were not significantly attenuated in those with baseline Ad5 seropositivity. Like DNA, rAd35 efficiently primed rAd5 boosting. All vaccine regimens tested elicited cross-clade antibody responses, including Env V1/V2-specific IgG responses.
CONCLUSIONS: Vaccine antigen delivery by rAd35 is well-tolerated and immunogenic as a prime to rAd5 immunization and as a boost to prior DNA immunization with the homologous insert. Further development of rAd35-vectored prime-boost vaccine regimens is warranted
Efficacy of Dupilumab in a Phase 2 Randomized Trial of Adults With Active Eosinophilic Esophagitis.
Eosinophilic esophagitis (EoE) is an allergen-mediated inflammatory disease with no approved treatment in the United States. Dupilumab, a VelocImmune-derived human monoclonal antibody against the interleukin (IL) 4 receptor, inhibits IL4 and IL13 signaling. Dupilumab is effective in the treatment of allergic, atopic, and type 2 diseases, so we assessed its efficacy and safety in patients with EoE.
We performed a phase 2 study of adults with active EoE (2 episodes of dysphagia/week with peak esophageal eosinophil density of 15 or more eosinophils per high-power field), from May 12, 2015, through November 9, 2016, at 14 sites. Participants were randomly assigned to groups that received weekly subcutaneous injections of dupilumab (300 mg, n = 23) or placebo (n = 24) for 12 weeks. The primary endpoint was change from baseline to week 10 in Straumann Dysphagia Instrument (SDI) patient-reported outcome (PRO) score. We also assessed histologic features of EoE (peak esophageal intraepithelial eosinophil count and EoE histologic scores), endoscopically visualized features (endoscopic reference score), esophageal distensibility, and safety.
The mean SDI PRO score was 6.4 when the study began. In the dupilumab group, SDI PRO scores were reduced by a mean value of 3.0 at week 10 compared with a mean reduction of 1.3 in the placebo group (P = .0304). At week 12, dupilumab reduced the peak esophageal intraepithelial eosinophil count by a mean 86.8 eosinophils per high-power field (reduction of 107.1%; P < .0001 vs placebo), the EoE-histologic scoring system (HSS) severity score by 68.3% (P < .0001 vs placebo), and the endoscopic reference score by 1.6 (P = .0006 vs placebo). Dupilumab increased esophageal distensibility by 18% vs placebo (P < .0001). Higher proportions of patients in the dupilumab group developed injection-site erythema (35% vs 8% in the placebo group) and nasopharyngitis (17% vs 4% in the placebo group).
In a phase 2 trial of patients with active EoE, dupilumab reduced dysphagia, histologic features of disease (including eosinophilic infiltration and a marker of type 2 inflammation), and abnormal endoscopic features compared with placebo. Dupilumab increased esophageal distensibility and was generally well tolerated. ClinicalTrials.gov, Number: NCT02379052
A systematic review and recommendations for prom instruments for older people with frailty in emergency care
Introduction
The current service metrics used to evaluate quality in emergency care do not account for specific healthcare outcome goals for older people living with frailty. These have previously been classified under themes of ‘Autonomy’ and ‘Functioning’. There is no person-reported outcome measure (PROM) for older people with frailty and emergency care needs. This study aimed to identify and co-produce recommendations for instruments potentially suitable for use in this population.
Methods
In this systematic review, we searched six databases for PROMs used between 2010 and 2021 by older people living with frailty receiving acute hospital care. Studies were reviewed against predefined eligibility criteria and appraised for quality using the COSMIN Risk of Bias checklist. Data were extracted to map instrument constructs against an existing framework of acute healthcare outcome goals. Instrument face and content validity were assessed by lay collaborators. Recommendations for instruments with potential emergency care suitability were formed through co-production.
Results
Of 9392 unique citations screened, we appraised the full texts of 158 studies. Nine studies were identified, evaluating nine PROMs. Quality of included studies ranged from ‘doubtful’ to ‘very good’. Most instruments had strong evidence for measurement properties. PROMs mainly assessed ‘Functioning’ constructs, with limited coverage of ‘Autonomy’. Five instruments were considered too burdensome for the emergency care setting or too specific for older people living with frailty.
Conclusions
Four PROMs were recommended as potentially suitable for further validation with older people with frailty and emergency care needs: COOP/WONCA charts, EuroQol, McGill Quality of Life (Expanded), and Palliative care Outcome Scale
Phenomenology of flavor-mediated supersymmetry breaking
The phenomenology of a new economical SUSY model that utilizes dynamical SUSY
breaking and gauge-mediation (GM) for the generation of the sparticle spectrum
and the hierarchy of fermion masses is discussed. Similarities between the
communication of SUSY breaking through a messenger sector, and the generation
of flavor using the Froggatt-Nielsen (FN) mechanism are exploited, leading to
the identification of vector-like messenger fields with FN fields, and the
messenger U(1) as a flavor symmetry. An immediate consequence is that the first
and second generation scalars acquire flavor-dependent masses, but do not
violate FCNC bounds since their mass scale, consistent with effective SUSY, is
of order 10 TeV. We define and advocate a minimal flavor-mediated model (MFMM),
recently introduced in the literature, that successfully accommodates the small
flavor-breaking parameters of the standard model using order one couplings and
ratios of flavon field vevs. The mediation of SUSY breaking occurs via two-loop
log-enhanced GM contributions, as well as several one-loop and two-loop
Yukawa-mediated contributions for which we provide analytical expressions. The
MFMM is parameterized by a small set of masses and couplings, with values
restricted by several model constraints and experimental data. The
next-to-lightest sparticle (NLSP) always has a decay length that is larger than
the scale of a detector, and is either the lightest stau or the lightest
neutralino. Similar to ordinary GM models, the best collider search strategies
are, respectively, inclusive production of at least one highly ionizing track,
or events with many taus plus missing energy. In addition, D^0 - \bar{D}^0
mixing is also a generic low energy signal. Finally, the dynamical generation
of the neutrino masses is briefly discussed.Comment: 54 pages, LaTeX, 8 figure
ParadisEO-MOEO: A Software Framework for Evolutionary Multi-Objective Optimization
This chapter presents ParadisEO-MOEO, a white-box object-oriented software framework dedicated to the flexible design of metaheuristics for multi-objective optimization. This paradigm-free software proposes a unified view for major evolutionary multi-objective metaheuristics. It embeds some features and techniques for multi-objective resolution and aims to provide a set of classes allowing to ease and speed up the development of computationally efficient programs. It is based on a clear conceptual distinction between the solution methods and the problems they are intended to solve. This separation confers a maximum design and code reuse. This general-purpose framework provides a broad range of fitness assignment strategies, the most common diversity preservation mechanisms, some elitistrelated features as well as statistical tools. Furthermore, a number of state-of-the-art search methods, including NSGA-II, SPEA2 and IBEA, have been implemented in a user-friendly way, based on the fine-grained ParadisEO-MOEO components
Indirect Dark Matter Detection from Dwarf Satellites: Joint Expectations from Astrophysics and Supersymmetry
We present a general methodology for determining the gamma-ray flux from
annihilation of dark matter particles in Milky Way satellite galaxies, focusing
on two promising satellites as examples: Segue 1 and Draco. We use the
SuperBayeS code to explore the best-fitting regions of the Constrained Minimal
Supersymmetric Standard Model (CMSSM) parameter space, and an independent MCMC
analysis of the dark matter halo properties of the satellites using published
radial velocities. We present a formalism for determining the boost from halo
substructure in these galaxies and show that its value depends strongly on the
extrapolation of the concentration-mass (c(M)) relation for CDM subhalos down
to the minimum possible mass. We show that the preferred region for this
minimum halo mass within the CMSSM with neutralino dark matter is ~10^-9-10^-6
solar masses. For the boost model where the observed power-law c(M) relation is
extrapolated down to the minimum halo mass we find average boosts of about 20,
while the Bullock et al (2001) c(M) model results in boosts of order unity. We
estimate that for the power-law c(M) boost model and photon energies greater
than a GeV, the Fermi space-telescope has about 20% chance of detecting a dark
matter annihilation signal from Draco with signal-to-noise greater than 3 after
about 5 years of observation
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