843 research outputs found
Radiometric observations at 20.6, 31.65, and 90.0 GHz: Continuing studies
Ground based radiometer measurements at 20.6, 31.65, and 90.0 GHz were analyzed to provide attenuation statistics, thus extending the data base of previous NAPEX studies. Using data from colocated radiosondes, comparisons of measurements and calculations of brightness temperatures are presented. The oxygen absorption model of Rosenkranz and the water vapor absorption models of Liebe and of Waters are used. Data from July 1987 at San Nicolas Island, California and from December 1987, August and November 1988 at Denver, Colorado, are included. Joint attenuation statistics at 20.6 and 31.65 GHz are presented for two locations of the Colorado Research Network for December 1987 and August 1988
Brightness temperature and attenuation statistics at 20.6 and 31.65 GHz
Attenuation and brightness temperature statistics at 20.6 and 31.65 GHz are analyzed for a year's worth of data. The data were collected in 1988 at Denver and Platteville, Colorado. The locations are separated by 49 km. Single-station statistics are derived for the entire year. Quality control procedures are discussed and examples of their application are given
Conformal anomaly from gauge fields without gauge fixing
We show how the Weyl anomaly generated by gauge fields, can be computed from
manifestly gauge invariant and diffeomorphism invariant exact renormalization
group equations, without having to fix the gauge at any stage. Regularisation
is provided by covariant higher derivatives and by embedding the Maxwell field
into a spontaneously broken supergauge theory. We first provide a
realisation that leaves behind two versions of the original gauge field,
and then construct a manifestly supergauge invariant flow equation
which leaves behind only the original Maxwell field in the spontaneously broken
regime.Comment: 24 page
Exploration of bivalent ligands targeting putative mu opioid receptor and chemokine receptor CCR5 dimerization
Modern antiretroviral therapies have provided HIV-1 infected patients longer lifespans and better quality of life. However, several neurological complications are now being seen in these patients due to HIV-1 associated injury of neurons by infected microglia and astrocytes. In addition, these effects can be further exacerbated with opiate use and abuse. One possible mechanism for such potentiation effects of opiates is the interaction of the mu opioid receptor (MOR) with the chemokine receptor CCR5 (CCR5), a known HIV-1 co-receptor, to form MOR-CCR5 heterodimer. In an attempt to understand this putative interaction and its relevance to neuroAIDS, we designed and synthesized a series of bivalent ligands targeting the putative CCR5-MOR heterodimer. To understand how these bivalent ligands may interact with the heterodimer, biological studies including calcium mobilization inhibition, binding affinity, HIV-1 invasion, and cell fusion assays were applied. In particular, HIV-1 infection assays using human peripheral blood mononuclear cells, macrophages, and astrocytes revealed a notable synergy in activity for one particular bivalent ligand. Further, a molecular model of the putative CCR5-MOR heterodimer was constructed, docked with the bivalent ligand, and molecular dynamics simulations of the complex was performed in a membrane-water system to help understand the biological observation
Capillary pressure of van der Waals liquid nanodrops
The dependence of the surface tension on a nanodrop radius is important for
the new-phase formation process. It is demonstrated that the famous Tolman
formula is not unique and the size-dependence of the surface tension can
distinct for different systems. The analysis is based on a relationship between
the surface tension and disjoining pressure in nanodrops. It is shown that the
van der Waals interactions do not affect the new-phase formation thermodynamics
since the effect of the disjoining pressure and size-dependent component of the
surface tension cancel each other.Comment: The paper is dedicated to the 80th anniversary of A.I. Rusano
Nucleation of Quark--Gluon Plasma from Hadronic Matter
The energy densities achieved during central collisions of large nuclei at
Brookhaven's AGS may be high enough to allow the formation of quark--gluon
plasma. Calculations based on relativistic nucleation theory suggest that rare
events, perhaps one in every 10 or 10, undergo the phase transition.
Experimental ramifications may include an enhancement in the ratio of pions to
baryons, a reduction in the ratio of deuterons to protons, and a larger source
size as seen by hadron interferometry.Comment: 22 pages, 7 figures available upon request, NUC--MINN--94/5--
The Spatial and Emission Properties of the Large [O III] Emission Nebula Near M31
Drechsler et al. (2023) reported the unexpected discovery of a 1.5 degree
long [O III] emission nebula 1.2 degrees southeast of the M31 nucleus. Here we
present additional images of this large emission structure, called SDSO, along
with radial velocity and flux measurements from low-dispersion spectra.
Independent sets of [O III] images show SDSO to be composed of broad streaks of
diffuse emission aligned NE-SW. Deep H images reveal no strong
coincident emission suggesting a high [O III]/H ratio. We also find no
other [O III] emission nebulosity as bright as SDSO within several degrees of
M31 and no filamentary H emission connected to SDSO. Optical spectra
taken along the arc's northern limb reveal [O III] 4959,5007
emissions matching the location and extent seen in our [O III] images. The
heliocentric velocity of this [O III] nebulosity is km s
with a peak surface brightness of erg s
cm arcsec (0.55 Rayleigh). We discuss SDSO as a possible
unrecognized supernova remnant, a large and unusually nearby planetary nebula,
a stellar bow shock nebula, or an interaction of M31's outer halo gas with
high-velocity circumgalactic gas. We conclude that galactic origins for SDSO
are unlikely and favor instead an extragalactic M31 halo--circumgalactic cloud
interaction scenario, despite the nebula's low radial velocity. We then
describe new observations that may help resolve the true nature and origin of
this large nebulosity so close to M31 in the sky.Comment: 21 pages, 12 figure
Feasibility of trial procedures for a randomised controlled trial of a community based group exercise intervention for falls prevention for visually impaired older people: the VIOLET study
Background Visually impaired older people (VIOP) have a higher risk of falling than their sighted peers, and are likely to avoid physical activity. The aim was to adapt the existing Falls Management Exercise (FaME) programme for VIOP, delivered in the community, and to investigate the feasibility of conducting a definitive randomised controlled trial (RCT) of this adapted intervention. Methods Two-centre randomised mixed methods pilot trial and economic evaluation of the adapted group-based FaME programme for VIOP versus usual care. A one hour exercise programme ran weekly over 12 weeks at the study sites (Newcastle and Glasgow), delivered by third sector (voluntary and community) organisations. Participants were advised to exercise at home for an additional two hours over the week. Those randomised to the usual activities group received no intervention. Outcome measures were completed at baseline, 12 and 24 weeks. The potential primary outcome was the Short Form Falls Efficacy Scale – International (SFES-I). Participants’ adherence was assessed by reviewing attendance records and self-reported compliance to the home exercises. Adherence with the course content (fidelity) by instructors was assessed by a researcher. Adverse events were collected in a weekly phone call. Results Eighteen participants, drawn from community-living VIOP were screened; 68 met the inclusion criteria; 64 participants were randomised with 33 allocated to the intervention and 31 to the usual activities arm. 94% of participants provided data at the 12 week visit and 92% at 24 weeks. Adherence was high. The intervention was found to be safe with 76% attending nine or more classes. Median time for home exercise was 50 min per week. There was little or no evidence that fear of falling, balance and falls risk, physical activity, emotional, attitudinal or quality of life outcomes differed between trial arms at follow-up. Conclusions The intervention, FaME, was implemented successfully for VIOP and all progression criteria for a main trial were met. The lack of difference between groups on fear of falling was unsurprising given it was a pilot study but there may have been other contributory factors including suboptimal exercise dose and apparent low risk of falls in participants. These issues need addressing for a future trial
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