753 research outputs found
Imaging Sources with Fast and Slow Emission Components
We investigate two-proton correlation functions for reactions in which fast
dynamical and slow evaporative proton emission are both present. In such cases,
the width of the correlation peak provides the most reliable information about
the source size of the fast dynamical component. The maximum of the correlation
function is sensitive to the relative yields from the slow and fast emission
components. Numerically inverting the correlation function allows one to
accurately disentangle fast dynamical from slow evaporative emission and
extract details of the shape of the two-proton source.Comment: 13 pages, 4 figure
Collective flow in central Au-Au collisions at 150, 250 and 400 A MeV
Radial collective flow and thermalization are studied in gold on gold
collisions at 150, 250 and 400 A MeV bombarding energies with a
relativistically covariant formulation of a QMD code. We find that radial flow
and "thermal" energies calculated for all the charged fragments agree
reasonably with the experimental values. The experimental hardware filter at
small angles used in the FOPI experiments at higher energies selects mainly the
thermalized particles.Comment: 4 pages with 4 EPS figures included. Version accepted for publication
in Phys. Rev.
A Cost-Effectiveness Analysis of a Community-Based Health Promotion Intervention for Adults with Mobility Impairments: Living Well with a Disability
This document reports on research conducted by the University of Montana and the University of Kansas for the Office of Disability and Health at the Centers for Disease Control and Prevention. The research project, conducted between August 1,1997 and July 31, 2001, was conducted in four separate but related studies. The research was conducted in eight States. We contracted with nine centers for independent living (CIL) to conduct 34 Living Well with a Disability health promotion workshops and to collect outcome measures. These programs included 246 individuals. In the first study, we evaluated the effectiveness and cost outcomes of the Living Well with a Disability health promotion program for adults with mobility impairments. The results of this study, conducted over 18 months, indicated participants= activity limitation due to secondary conditions was substantially reduced. Responding to items from the BRFSS Quality of Life module, individuals reported gaining more than a full day without physical and mental symptoms following the program
Withdrawal from treatment as an outcome in the Isolde study of COPD
Objectives: To investigate the determinants of patient withdrawal from our study, and the effect
of these withdrawals on the outcome of treatment with inhaled corticosteroids in patients with
COPD.
Design: A double-blind, placebo-controlled, randomized trial.
Setting: Eighteen outpatient centers in the United Kingdom.
Participants: Seven hundred fifty-one patients with stable COPD defined clinically as baseline postbronchodilator FEV1 > 0.8 L and < 85% predicted, FEV1/FVC ratio < 70%, and FEV1 change after albuterol < 10% of predicted.
Intervention: Random assignment of either 500 micrograms bid of inhaled fluticasone propionate (FP)using a spacer device or an identical placebo inhaler. Treatment was continued for 3 years or
until patients withdrew from follow-up.
Measurements and results: Postbronchodilator FEV1 was measured on three occasions before
randomization and every 3 months thereafter. Health status was assessed by the disease-specific
St. George Respiratory Questionnaire (SGRQ) and the modified short-form 36 questionnaire
(SF-36) at baseline and every 6 months. Three hundred thirty-nine patients withdrew, of whom
156 patients received FP. Prescription of frequent courses of oral prednisolone was the most
common reason for withdrawing as specified in the protocol (69 patients in the FP group
withdrew due to respiratory symptoms, compared with 93 patients in the placebo group). This
explained the significantly greater dropout of placebo-treated patients that was most evident
when FEV1 was < 50% predicted. Patients withdrawing had a significantly more rapid decline in health status, measured by both the SGRQ and the SF-36 (p < 0.001). Those withdrawing from the placebo group had a more rapid decline in FEV1 and more exacerbations than the FP-treated
groups. Baseline FEV1 was lower in dropouts than in patients completing the study receiving
placebo, but there was no difference between the respective groups receiving FP.
Conclusions: Patients who withdrew from follow-up were those with the most rapidly deteriorating
health status and lung function. Losing these patients from the final analysis can reduce the
power of a study to achieve its primary end point
System-size dependence of the pion freeze-out volume as a potential signature for the phase transition to a Quark Gluon Plasma
Hanburry-Brown-Twiss (HBT) correlation functions and radii of negatively
charged pions from C+C, Si+Si, Cu+Cu, and In+In at lower RHIC/SPS energies are
calculated with the UrQMD transport model and the CRAB analyzing program. We
find a minimum in the excitation function of the pion freeze-out volume at low
transverse momenta and around GeV which can be related to
the transition from hadronic to string matter (which might be interpreted as a
pre-cursor of the QGP). The existence of the minimum is explained by the
competition of two mechanisms of the particle production, resonance decays and
string formation/fragmentation.Comment: 12 pages, 4 fig
Probing Transport Theories via Two-Proton Source Imaging
Imaging technique is applied to two-proton correlation functions to extract
quantitative information about the space-time properties of the emitting source
and about the fraction of protons that can be attributed to fast emission
mechanisms. These new analysis techniques resolve important ambiguities that
bedeviled prior comparisons between measured correlation functions and those
calculated by transport theory. Quantitative comparisons to transport theory
are presented here. The results of the present analysis differ from those
reported previously for the same reaction systems. The shape of the two-proton
emitting sources are strongly sensitive to the details about the in-medium
nucleon-nucleon cross sections and their density dependence.Comment: 23 pages, 11 figures. Figures are in GIF format. If you need
postscript format, please contact: [email protected]
Space-time evolution and HBT analysis of relativistic heavy ion collisions in a chiral SU(3) x SU(3) model
The space-time dynamics and pion-HBT radii in central heavy ion-collisions at
CERN-SPS and BNL-RHIC are investigated within a hydrodynamic simulation. The
dependence of the dynamics and the HBT-parameters on the EoS is studied with
different parametrisations of a chiral SU(3) sigma-omega model. The
selfconsistent collective expansion includes the effects of effective hadron
masses, generated by the nonstrange and strange scalar condensates. Different
chiral EoS show different types of phase transitions and even a crossover. The
influence of the order of the phase transition and of the difference in the
latent heat on the space-time dynamics and pion-HBT radii is studied. A small
latent heat, i.e. a weak first-order chiral phase transition, or even a smooth
crossover leads to distinctly different HBT predictions than a strong first
order phase transition. A quantitative description of the data, both at SPS
energies as well as at RHIC energies, appears difficult to achieve within the
ideal hydrodynamical approach using the SU(3) chiral EoS. A strong first-order
quasi-adiabatic chiral phase transition seems to be disfavored by the pion-HBT
data from CERN-SPS and BNL-RHIC
Umbilical cord mesenchymal stem cells for COVID-19 acute respiratory distress syndrome: A double-blind, phase 1/2a, randomized controlled trial
Acute respiratory distress syndrome (ARDS) in COVID-19 is associated with high mortality. Mesenchymal stem cells are known to exert immunomodulatory and anti-inflammatory effects and could yield beneficial effects in COVID-19 ARDS. The objective of this study was to determine safety and explore efficacy of umbilical cord mesenchymal stem cell (UC-MSC) infusions in subjects with COVID-19 ARDS. A double-blind, phase 1/2a, randomized, controlled trial was performed. Randomization and stratification by ARDS severity was used to foster balance among groups. All subjects were analyzed under intention to treat design. Twenty-four subjects were randomized 1:1 to either UC-MSC treatment (n = 12) or the control group (n = 12). Subjects in the UC-MSC treatment group received two intravenous infusions (at day 0 and 3) of 100 ± 20 × 106 UC-MSCs; controls received two infusions of vehicle solution. Both groups received best standard of care. Primary endpoint was safety (adverse events [AEs]) within 6 hours; cardiac arrest or death within 24 hours postinfusion). Secondary endpoints included patient survival at 31 days after the first infusion and time to recovery. No difference was observed between groups in infusion-associated AEs. No serious adverse events (SAEs) were observed related to UC-MSC infusions. UC-MSC infusions in COVID-19 ARDS were found to be safe. Inflammatory cytokines were significantly decreased in UC-MSC-treated subjects at day 6. Treatment was associated with significantly improved patient survival (91% vs 42%, P =.015), SAE-free survival (P =.008), and time to recovery (P =.03). UC-MSC infusions are safe and could be beneficial in treating subjects with COVID-19 ARDS
Expanding the genetic and phenotypic spectrum of ACTA2-related vasculopathies in a Dutch cohort
Purpose: Heterozygous pathogenic/likely pathogenic (P/LP) variants in the ACTA2 gene confer a high risk for thoracic aortic aneurysms and aortic dissections. This retrospective multicenter study elucidates the clinical outcome of ACTA2-related vasculopathies. Methods: Index patients and relatives with a P/LP variant in ACTA2 were included. Data were collected through retrospective review of medical records using a standardized questionnaire. Results: A total of 49 individuals from 28 families participated in our study. In total, 20 different ACTA2 variants were detected. Aortic events occurred in 65% of the cases (78.6% index patients and 47.6% relatives). Male sex and hypertension emerged as significantly associated with aortic events. Of 20 individuals, 5 had an aortic diameter of <45 mm (1.77 inches) at the time of the type A dissection. Mean age at first aortic event was 49.0 ± 12.4 years. Severe surgical complications for type A and type B dissection occurred in 25% and 16.7% of the cases and in-hospital mortality rates were 9.5% and 0%, respectively. Conclusion: P/LP ACTA2 variants are associated with an increased risk for an aortic event and age-related penetrance, which emphasizes the importance of early recognition of the disease. Caregivers should be aware of the risk for aortic dissections, even in individuals with aortic diameters within the normal range
K^+ production in the reaction at incident energies from 1 to 2 AGeV
Semi-inclusive triple differential multiplicity distributions of positively
charged kaons have been measured over a wide range in rapidity and transverse
mass for central collisions of Ni with Ni nuclei. The transverse
mass () spectra have been studied as a function of rapidity at a beam
energy 1.93 AGeV. The distributions of K^+ mesons are well described by a
single Boltzmann-type function. The spectral slopes are similar to that of the
protons indicating that rescattering plays a significant role in the
propagation of the kaon. Multiplicity densities have been obtained as a
function of rapidity by extrapolating the Boltzmann-type fits to the measured
distributions over the remaining phase space. The total K^+ meson yield has
been determined at beam energies of 1.06, 1.45, and 1.93 AGeV, and is presented
in comparison to existing data. The low total yield indicates that the K^+
meson can not be explained within a hadro-chemical equilibrium scenario,
therefore indicating that the yield does remain sensitive to effects related to
its production processes such as the equation of state of nuclear matter and/or
modifications to the K^+ dispersion relation.Comment: 24 pages Latex (elsart) 7 PS figures to be submitted to Nucl. Phys
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