74 research outputs found
photoproduction on the proton for photon energies from 0.725 to 2.875 GeV
Differential cross sections for the reaction have been
measured with the CEBAF Large Acceptance Spectrometer (CLAS) and a tagged
photon beam with energies from 0.725 to 2.875 GeV. Where available, the results
obtained here compare well with previously published results for the reaction.
Agreement with the SAID and MAID analyses is found below 1 GeV. The present set
of cross sections has been incorporated into the SAID database, and exploratory
fits have been made up to 2.7 GeV. Resonance couplings have been extracted and
compared to previous determinations. With the addition of these cross sections
to the world data set, significant changes have occurred in the high-energy
behavior of the SAID cross-section predictions and amplitudes.Comment: 18 pages, 10 figure
Differential cross sections and spin density matrix elements for the reaction gamma p -> p omega
High-statistics differential cross sections and spin density matrix elements
for the reaction gamma p -> p omega have been measured using the CLAS at
Jefferson Lab for center-of-mass (CM) energies from threshold up to 2.84 GeV.
Results are reported in 112 10-MeV wide CM energy bins, each subdivided into
cos(theta_CM) bins of width 0.1. These are the most precise and extensive omega
photoproduction measurements to date. A number of prominent structures are
clearly present in the data. Many of these have not previously been observed
due to limited statistics in earlier measurements
Bone Is Not Essential for Osteoclast Activation
Background: The mechanism whereby bone activates resorptive behavior in osteoclasts, the cells that resorb bone, is
unknown. It is known that avb3 ligands are important, because blockade of avb3 receptor signaling inhibits bone resorption, but this might be through inhibition of adhesion or migration rather than resorption itself. Nor is it known whether avb3 ligands are sufficient for resorption the consensus is that bone mineral is essential for the recognition of bone as the substrate appropriate for resorption.
Methodology/Principal Findings: Vitronectin- but not fibronectin-coated coverslips induced murine osteoclasts to secrete tartrate-resistant acid phosphatase, as they do on bone. Osteoclasts incubated on vitronectin, unlike fibronectin, formed podosome belts on glass coverslips, and these were modulated by resorption-regulating cytokines. Podosome belts formed on vitronectin-coated surfaces whether the substrates were rough or smooth, rigid or flexible. We developed a novel approach whereby the substrate-apposed surface of cells can be visualized in the scanning electron microscope. With this approach, supported by transmission electron microscopy, we found that osteoclasts on vitronectin-coated surfaces show ruffled borders and clear zones characteristic of resorbing osteoclasts. Ruffles were obscured by a film if cells were
incubated in the cathepsin inhibitor E64, suggesting that removal of the film represents substrate-degrading behavior.
Analogously, osteoclasts formed resorption-like trails on vitronectin-coated substrates. Like bone resorption, these trails were dependent upon resorbogenic cytokines and were inhibited by E64. Bone mineral induced actin rings and surface excavation only if first coated with vitronectin. Fibronectin could not substitute in any of these activities, despite enabling adhesion and cell spreading.
Conclusions/Significance: Our results show that ligands avb3 are not only necessary but sufficient for the induction of resorptive behavior in osteoclasts; and suggest that bone is recognized through its affinity for these ligands, rather than by its mechanical or topographical attributes, or through a putative ‘mineral receptor’
Integrating an internet-mediated walking program into family medicine clinical practice: a pilot feasibility study
<p>Abstract</p> <p>Background</p> <p>Regular participation in physical activity can prevent many chronic health conditions. Computerized self-management programs are effective clinical tools to support patient participation in physical activity. This pilot study sought to develop and evaluate an online interface for primary care providers to refer patients to an Internet-mediated walking program called Stepping Up to Health (SUH) and to monitor participant progress in the program.</p> <p>Methods</p> <p>In Phase I of the study, we recruited six pairs of physicians and medical assistants from two family practice clinics to assist with the design of a clinical interface. During Phase II, providers used the developed interface to refer patients to a six-week pilot intervention. Provider perspectives were assessed regarding the feasibility of integrating the program into routine care. Assessment tools included quantitative and qualitative data gathered from semi-structured interviews, surveys, and online usage logs.</p> <p>Results</p> <p>In Phase I, 13 providers used SUH and participated in two interviews. Providers emphasized the need for alerts flagging patients who were not doing well and the ability to review participant progress. Additionally, providers asked for summary views of data across all enrolled clinic patients as well as advertising materials for intervention recruitment. In response to this input, an interface was developed containing three pages: 1) a recruitment page, 2) a summary page, and 3) a detailed patient page. In Phase II, providers used the interface to refer 139 patients to SUH and 37 (27%) enrolled in the intervention. Providers rarely used the interface to monitor enrolled patients. Barriers to regular use of the intervention included lack of integration with the medical record system, competing priorities, patient disinterest, and physician unease with exercise referrals. Intention-to-treat analyses showed that patients increased walking by an average of 1493 steps/day from pre- to post-intervention (<it>t </it>= (36) = 4.13, <it>p </it>< 0.01).</p> <p>Conclusions</p> <p>Providers successfully referred patients using the SUH provider interface, but were less willing to monitor patient compliance in the program. Patients who completed the program significantly increased their step counts. Future research is needed to test the effectiveness of integrating SUH with clinical information systems over a longer evaluation period.</p
Scoring method of a Situational Judgment Test:influence on internal consistency reliability, adverse impact and correlation with personality?
textabstractSituational Judgment Tests (SJTs) are increasingly used for medical school selection. Scoring an SJT is more complicated than scoring a knowledge test, because there are no objectively correct answers. The scoring method of an SJT may influence the construct and concurrent validity and the adverse impact with respect to non-traditional students. Previous research has compared only a small number of scoring methods and has not studied the effect of scoring method on internal consistency reliability. This study compared 28 different scoring methods for a rating SJT on internal consistency reliability, adverse impact and correlation with personality. The scoring methods varied on four aspects: the way of controlling for systematic error, and the type of reference group, distance and central tendency statistic. All scoring methods were applied to a previously validated integrity-based SJT, administered to 931 medical school applicants. Internal consistency reliability varied between .33 and .73, which is likely explained by the dependence of coefficient alpha on the total score variance. All scoring methods led to significantly higher scores for the ethnic majority than for the non-Western minorities, with effect sizes ranging from 0.48 to 0.66. Eighteen scoring methods showed a significant small positive correlation with agreeableness. Four scoring methods showed a significant small positive correlation with conscientiousness. The way of controlling for systematic error was the most influential scoring method aspect. These results suggest that the increased use of SJTs for selection into medical school must be accompanied by a thorough examination of the scoring method to be used
Beam-Recoil Polarization Transfer in the Nucleon Resonance Region in the Exclusive and Reactions at CLAS
Beam-recoil transferred polarizations for the exclusive reactions have been measured using the CLAS
spectrometer at Jefferson Laboratory. New measurements have been completed at
beam energies of 4.261 and 5.754 GeV that span a range of momentum transfer
from 0.7 to 5.4 GeV, invariant energy from 1.6 to 2.6 GeV, and
the full center-of-mass angular range of the meson. These new data add to
the existing CLAS measurements at 2.567 GeV, and provide the
first-ever data for the channel in electroproduction. Comparisons
of the data with several theoretical models are used to study the sensitivity
to s-channel resonance contributions and the underlying reaction mechanism.
Interpretations within two semi-classical partonic models are made to probe the
underlying reaction mechanism and the quark-pair creation dynamics.Comment: 48 pages, 22 figure
A measurement of the differential cross section for the reaction from deuterium
We report a measurement of the differential cross section for the process from the CLAS detector at Jefferson Lab in Hall B for
photon energies between 1.0 and 3.5 GeV and pion center-of-mass (c.m.) angles
() between 50 and 115. We confirm a previous
indication of a broad enhancement around a c.m. energy () of 2.2 GeV
at in the scaled differential cross section, . Our data show the angular dependence of this enhancement
as the scaling region is approached in the kinematic region from 70 to
105.Comment: 6 pages, 3 figures. submitted to PR
The extraction of total cross section from
We report on the first measurement of the differential cross section of
-meson photoproduction for the exclusive
reaction channel. The experiment was performed using a
\textcolor{black}{tagged-photon} beam and the CEBAF Large Acceptance
Spectrometer (CLAS) at Jefferson Lab. A combined analysis using data from the
channel and those from a previous publication on
coherent production on the deuteron has been carried out to extract the
total cross section, . The extracted total
cross section favors a value above 20 mb. This value is larger than the value
extracted using vector-meson dominance models for photoproduction on the
proton.Comment: 7 pages 4 figure
All-sky search for gravitational-wave bursts in the second joint LIGO-Virgo run
We present results from a search for gravitational-wave bursts in the data
collected by the LIGO and Virgo detectors between July 7, 2009 and October 20,
2010: data are analyzed when at least two of the three LIGO-Virgo detectors are
in coincident operation, with a total observation time of 207 days. The
analysis searches for transients of duration < 1 s over the frequency band
64-5000 Hz, without other assumptions on the signal waveform, polarization,
direction or occurrence time. All identified events are consistent with the
expected accidental background. We set frequentist upper limits on the rate of
gravitational-wave bursts by combining this search with the previous LIGO-Virgo
search on the data collected between November 2005 and October 2007. The upper
limit on the rate of strong gravitational-wave bursts at the Earth is 1.3
events per year at 90% confidence. We also present upper limits on source rate
density per year and Mpc^3 for sample populations of standard-candle sources.
As in the previous joint run, typical sensitivities of the search in terms of
the root-sum-squared strain amplitude for these waveforms lie in the range 5
10^-22 Hz^-1/2 to 1 10^-20 Hz^-1/2. The combination of the two joint runs
entails the most sensitive all-sky search for generic gravitational-wave bursts
and synthesizes the results achieved by the initial generation of
interferometric detectors.Comment: 15 pages, 7 figures: data for plots and archived public version at
https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=70814&version=19, see
also the public announcement at
http://www.ligo.org/science/Publication-S6BurstAllSky
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