1,180 research outputs found
Ultraviolet Imaging Polarimetry of the Large Magellanic Cloud. II. Models
Motivated by new sounding-rocket wide-field polarimetric images of the Large
Magellanic Cloud, we have used a three-dimensional Monte Carlo radiation
transfer code to investigate the escape of near-ultraviolet photons from young
stellar associations embedded within a disk of dusty material (i.e. a galaxy).
As photons propagate through the disk, they may be scattered or absorbed by
dust. Scattered photons are polarized and tracked until they escape to be
observed; absorbed photons heat the dust, which radiates isotropically in the
far-infrared, where the galaxy is optically thin. The code produces four output
images: near- UV and far-IR flux, and near-UV images in the linear Stokes
parameters Q and U. From these images we construct simulated UV polarization
maps of the LMC. We use these maps to place constraints on the star + dust
geometry of the LMC and the optical properties of its dust grains. By tuning
the model input parameters to produce maps that match the observed polarization
maps, we derive information about the inclination of the LMC disk to the plane
of the sky, and about the scattering phase function g. We compute a grid of
models with i = 28 deg., 36 deg., and 45 deg., and g = 0.64, 0.70, 0.77, 0.83,
and 0.90. The model which best reproduces the observed polarization maps has i
= 36 +2/-5 degrees and g ~0.7. Because of the low signal-to-noise in the data,
we cannot place firm constraints on the value of g. The highly inclined models
do not match the observed centro-symmetric polarization patterns around bright
OB associations, or the distribution of polarization values. Our models
approximately reproduce the observed ultraviolet photopolarimetry of the
western side of the LMC; however, the output images depend on many input
parameters and are nonunique.Comment: Accepted to AJ. 20 pages, 7 figure
Plasma osteopontin concentrations in preeclampsia - is there an association with endothelial injury?
Background: It has been previously reported that plasma
osteopontin (OPN) concentrations are increased in cardiovascular
disorders. The goal of the present study was to determine plasma
OPN concentrations in healthy pregnant women and preeclamptic
patients, and to investigate their relationship to the clinical
characteristics of the study subjects and to markers of
inflammation [C-reactive protein (CRP)], endothelial activation
[von Willebrand factor antigen (VWF: Ag)] or endothelial injury
(fibronectin), oxidative stress [malondialdehyde (MDA)] and
trophoblast debris (cell-free fetal DNA). Methods: Forty-four
patients with preeclampsia and 44 healthy pregnant women matched
for age and gestational age were involved in this case-control
study. Plasma OPN concentrations were measured with ELISA. Serum
CRP concentrations were determined with an autoanalyzer using
the manufacturer's reagents. Plasma VWF: Ag was quantified by
ELISA, while plasma fibronectin concentrations were measured by
nephelometry. Plasma MDA concentrations were estimated by the
thiobarbituric acid-based colorimetric assay. The amount of
cell-free fetal DNA in maternal plasma was determined by
quantitative real-time PCR analysis of the sex-determining
region Y (SRY) gene. For statistical analyses, non-parametric
methods were applied. Results: Serum levels of CRP, as well as
plasma concentrations of VWF: Ag, fibronectin, MDA and cell-free
fetal DNA were significantly higher in preeclamptic patients
than in healthy pregnant women. There was no significant
difference in plasma OPN concentrations between controls and the
preeclamptic group. However, preeclamptic patients with plasma
fibronectin concentrations in the upper quartile had
significantly higher plasma OPN concentrations than those below
the 75th percentile, as well as healthy pregnant women [median
(interquartile range): 9.38 (8.10-11.99) vs. 7.54 (6.31-9.40)
and 7.40 (6.51-8.80) ng/mL, respectively, p < 0.05 for both].
Furthermore, in preeclamptic patients, plasma OPN concentrations
showed a significant positive linear association with plasma
fibronectin (Spearman R = 0.38, standardized regression
coefficient (beta) = 0.41, p < 0.05 for both). Conclusions:
Plasma OPN concentrations are increased in preeclamptic patients
with extensive endothelial injury. However, further studies are
warranted to explore the relationship between OPN and
endothelial damage. Clin Chem Lab Med 2010;48: 181-7
Nuclear structure and reaction studies at SPIRAL
The SPIRAL facility at GANIL, operational since 2001, is described briefly.
The diverse physics program using the re-accelerated (1.2 to 25 MeV/u) beams
ranging from He to Kr and the instrumentation specially developed for their
exploitation are presented. Results of these studies, using both direct and
compound processes, addressing various questions related to the existence of
exotic states of nuclear matter, evolution of new "magic numbers", tunnelling
of exotic nuclei, neutron correlations, exotic pathways in astrophysical sites
and characterization of the continuum are discussed. The future prospects for
the facility and the path towards SPIRAL2, a next generation ISOL facility, are
also briefly presented.Comment: 48 pages, 27 figures. Accepted for publication in Journal of Physics
An investigation of factors associated with the health and well-being of HIV-infected or HIV-affected older people in rural South Africa
BackgroundDespite the severe impact of HIV in sub-Saharan Africa, the health of older people aged 50+ is often overlooked owing to the dearth of data on the direct and indirect effects of HIV on older people's health status and well-being. The aim of this study was to examine correlates of health and well-being of HIV-infected older people relative to HIV-affected people in rural South Africa, defined as participants with an HIV-infected or death of an adult child due to HIV-related cause. MethodsData were collected within the Africa Centre surveillance area using instruments adapted from the World Health Organization (WHO) Study on global AGEing and adult health (SAGE). A stratified random sample of 422 people aged 50+ participated. We compared the health correlates of HIV-infected to HIV-affected participants using ordered logistic regressions. Health status was measured using three instruments: disability index, quality of life and composite health score. ResultsMedian age of the sample was 60 years (range 50-94). Women HIV-infected (aOR 0.15, 95% confidence interval (CI) 0.08-0.29) and HIV-affected (aOR 0.20, 95% CI 0.08-0.50), were significantly less likely than men to be in good functional ability. Women's adjusted odds of being in good overall health state were similarly lower than men's; while income and household wealth status were stronger correlates of quality of life. HIV-infected participants reported better functional ability, quality of life and overall health state than HIV-affected participants. Discussion and Conclusions The enhanced healthcare received as part of anti-retroviral treatment as well as the considerable resources devoted to HIV care appear to benefit the overall well-being of HIV-infected older people; whereas similar resources have not been devoted to the general health needs of HIV uninfected older people. Given increasing numbers of older people, policy and programme interventions are urgently needed to holistically meet the health and well-being needs of older people beyond the HIV-related care system. <br/
Tips for implementing multigrid methods on domains containing holes
As part of our development of a computer code to perform 3D `constrained
evolution' of Einstein's equations in 3+1 form, we discuss issues regarding the
efficient solution of elliptic equations on domains containing holes (i.e.,
excised regions), via the multigrid method. We consider as a test case the
Poisson equation with a nonlinear term added, as a means of illustrating the
principles involved, and move to a "real world" 3-dimensional problem which is
the solution of the conformally flat Hamiltonian constraint with Dirichlet and
Robin boundary conditions. Using our vertex-centered multigrid code, we
demonstrate globally second-order-accurate solutions of elliptic equations over
domains containing holes, in two and three spatial dimensions. Keys to the
success of this method are the choice of the restriction operator near the
holes and definition of the location of the inner boundary. In some cases (e.g.
two holes in two dimensions), more and more smoothing may be required as the
mesh spacing decreases to zero; however for the resolutions currently of
interest to many numerical relativists, it is feasible to maintain second order
convergence by concentrating smoothing (spatially) where it is needed most.
This paper, and our publicly available source code, are intended to serve as
semi-pedagogical guides for those who may wish to implement similar schemes.Comment: 18 pages, 11 figures, LaTeX. Added clarifications and references re.
scope of paper, mathematical foundations, relevance of work. Accepted for
publication in Classical & Quantum Gravit
Physical characterixation and in vitro biological impact of highly aggregated antibodies separated into size-enriched populations by fluorescence-activated cell sorting
An IgG2 monoclonal antibody (mAb) solution was subjected to stirring, generating high concentrations of nanometer and subvisible particles, which were then successfully size enriched into different size bins by low speed centrifugation or a combination of gravitational sedimentation and Fluorescence-Activated Cell Sorting (FACS). The size-fractionated mAb particles were assessed for their ability to elicit the release of cytokines from a population of donor-derived human peripheral blood mononuclear cells (PBMC) at two phases of the immune response. Fractions enriched in nanometer-sized particles showed a lower response than those enriched in micron-sized particles in this assay. Particles of 5â10 ÎŒm in size displayed elevated cytokine release profiles compared to other size ranges. Stir-stressed mAb particles had amorphous morphology, contained protein with partially altered secondary structure, elevated surface hydrophobicity (compared to controls), and trace levels of elemental fluorine. FACS size-enriched the mAb particle samples, yet did not notably alter the overall morphology or composition of particles as measured by Microflow imaging, Transmission Electron Microscopy, and Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy. The utility and limitations of FACS for size separation of mAb particles and potential of in-vitro PBMC studies to rank order the immunogenic potential of various types of mAb particles is discussed
The synergistic and neuroprotective effects of alcoholâantioxidant treatment on bloodâbrain barrier endothelial cells
Background: Alcohol (EtOH) is reported to adversely affect one of the most crucial roles of the bloodâbrain barrier (BBB), the regulation of its permeability, thereby compromising the stability of the homeostatic environment of the brain. The central component of the BBB, endothelial cells (ECs), regulates BBB transcellular transport, while their paracellular pathways are made virtually impermeable by molecular structures called tight junctions (TJs). These TJs are composed of proteins, such as claudin-5, a protein involved in the regulation of paracellular permeability and of key interest in this study. Methods and Results: The working hypothesis of this study postulated that the high levels of antioxidants (AOs) in the fermented Aspalathus linearis (Rooibos; Rf) tincture may protect the ECs of the BBB against oxidative stress induced by EtOH exposure. Cells were exposed for 24 hours to selected concentrations of EtOH (25 and 100 mM), Rf (containing an antioxidant equivalence of 1.9 nM Aspalathin), and cotreatments of EtOH and Rf. Cell viability, live cell number, and toxicity were analyzed using the trypan blue exclusion assay. RT-qPCR was implemented to quantify claudin-5 transcription. In addition, permeability (Transepithelial Electrical Resistance) of bEnd5 monolayers was measured. The experimental timeline for the above-mentioned parameters was 24 and 48 hours. Conclusions: Our study showed that simultaneous exposure of Rf and EtOH was able to negate the effects of EtOH on cell viability and cell proliferation, but was not able to reverse or reduce the effects of EtOH on claudin-5 transcription and paracellular permeability. Furthermore, a novel finding in this study suggests that very low concentrations of AOs in tinctures such as Rooibos tea could profoundly alter the redox status of brain ECs
Superconductivity in Fullerides
Experimental studies of superconductivity properties of fullerides are
briefly reviewed. Theoretical calculations of the electron-phonon coupling, in
particular for the intramolecular phonons, are discussed extensively. The
calculations are compared with coupling constants deduced from a number of
different experimental techniques. It is discussed why the A_3 C_60 are not
Mott-Hubbard insulators, in spite of the large Coulomb interaction. Estimates
of the Coulomb pseudopotential , describing the effect of the Coulomb
repulsion on the superconductivity, as well as possible electronic mechanisms
for the superconductivity are reviewed. The calculation of various properties
within the Migdal-Eliashberg theory and attempts to go beyond this theory are
described.Comment: 33 pages, latex2e, revtex using rmp style, 15 figures, submitted to
Review of Modern Physics, more information at
http://radix2.mpi-stuttgart.mpg.de/fullerene/fullerene.htm
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Health-related quality of life in patients with a germline BRCA mutation and metastatic pancreatic cancer receiving maintenance olaparib
Background: Patients with metastatic pancreatic cancer often have a detriment in health-related quality of life (HRQoL). In the randomized, double-blind, phase III POLO trial progression-free survival was significantly longer with maintenance olaparib, a poly(ADP-ribose) polymerase inhibitor, than placebo in patients with a germline BRCA1 and/or BRCA2 mutation (gBRCAm) and metastatic pancreatic cancer whose disease had not progressed during first-line platinum-based chemotherapy. The prespecified HRQoL evaluation is reported here. Patients and methods: Patients were randomized to receive maintenance olaparib (300 mg b.i.d.; tablets) or placebo. HRQoL was assessed using the European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire Core 30-item module at baseline, every 4 weeks until disease progression, at discontinuation, and 30 days after last dose. Scores ranged from 0 to 100; a â„10-point change or difference between arms was considered clinically meaningful. Adjusted mean change from baseline was analysed using a mixed model for repeated measures. Time to sustained clinically meaningful deterioration (TSCMD) was analysed using a log-rank test. Results: Of 154 randomized patients, 89 of 92 olaparib-arm and 58 of 62 placebo-arm patients were included in HRQoL analyses. The adjusted mean change in Global Health Status (GHS) score from baseline was <10 points in both arms and there was no significant between-group difference [-2.47; 95% confidence interval (CI) -7.27, 2.33; P = 0.31]. Analysis of physical functioning scores showed a significant between-group difference (-4.45 points; 95% CI -8.75, -0.16; P = 0.04). There was no difference in TSCMD for olaparib versus placebo for GHS [P = 0.25; hazard ratio (HR) 0.72; 95% CI 0.41, 1.27] or physical functioning (P = 0.32; HR 1.38; 95% CI 0.73, 2.63). Conclusions: HRQoL was preserved with maintenance olaparib treatment with no clinically meaningful difference compared with placebo. These results support the observed efficacy benefit of maintenance olaparib in patients with a gBRCAm and metastatic pancreatic cancer. ClincalTrials.gov number: NCT02184195
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