798 research outputs found
Evaluation of Compton scattering sequence reconstruction algorithms for a portable position sensitive radioactivity detector based on pixelated Cd(Zn)Te crystals
We present extensive simulation studies on the performance of algorithms for
the Compton sequence reconstruction used for the development of a portable
spectroscopic instrument (COCAE), with the capability to localize and identify
radioactive sources, by exploiting the Compton scattering imaging. Various
Compton Sequence reconstruction algorithms have been compared using a large
number of simulated events. These algorithms are based on Compton kinematics,
as well as on statistical test criteria that exploit the redundant information
of events having two or more photon interactions in the active detector's
volume. The efficiency of the best performing technique is estimated for a wide
range of incident gamma-ray photons emitted from point-like gamma sources.Comment: 16 pages, 17 figure
Simulated Performance Of Algorithms For The Localization Of Radioactive Sources From A Position Sensitive Radiation Detecting System (COCAE)
Simulation studies are presented regarding the performance of algorithms that
localize point-like radioactive sources detected by a position sensitive
portable radiation instrument (COCAE). The source direction is estimated by
using the List Mode Maximum Likelihood Expectation Maximization (LM-ML-EM)
imaging algorithm. Furthermore, the source-to-detector distance is evaluated by
three different algorithms based on the photo-peak count information of each
detecting layer, on the quality of the reconstructed source image as well as on
the triangulation method. These algorithms have been tested on a large number
of simulated photons in a wide energy range (from 200keV up to 2MeV) emitted by
point-like radioactive sources located at different orientation and
source-to-detector distances.Comment: 8 pages, 7 figures, 11th International Conference on Applications of
Nuclear Techniques, Crete, Greece, June 12-18, 201
The Micromegas detector of the CAST experiment
A low background Micromegas detector has been operating in the CAST
experiment at CERN for the search of solar axions during the first phase of the
experiment (2002-2004). The detector, made out of low radioactivity materials,
operated efficiently and achieved a very low level of background rejection (5 x
10^-5 counts/keV/cm^2/s) without shielding.Comment: 13 pages, 12 figures and images, submitted to New Journal o
Designing a multifaceted quality improvement intervention in primary care in a country where general practice is seeking recognition: the case of Cyprus
<p>Abstract</p> <p>Background</p> <p>Quality Improvement Interventions require significant financial investments, and therefore demand careful consideration in their design in order to maximize potential benefits. In this correspondence we present the methodological approach of a multifaceted quality improvement intervention aiming to improve quality of care in primary care, properly tailored for a country such as Cyprus where general practice is currently seeking recognition.</p> <p>Methods</p> <p>Our methodological approach was focused on the design of an open label, community-based intervention controlled trial using all patients from two urban and two rural public primary care centers diagnosed with hypertension and type II diabetes mellitus. The design of our intervention was grounded on a strong theoretical framework that included the Unified Theory of Acceptance and Use of Technology, and the Chronic Care Model, which synthesize evidence-based system changes in accordance with the Theory of Planned Behavior and the Theory of Reasoned Action. The primary outcome measure was improvement in the quality of care for two chronic diseases evaluated through specific clinical indicators, as well as the patient satisfaction assessed by the EUROPEP questionnaire and additional personal interviews.</p> <p>Results</p> <p>We designed a multifaceted quality improvement intervention model, supported by a varying degree of scientific evidence, tailored to local needs and specific country characteristics. Overall, the main components of the intervention were the development and adoption of an electronic medical record and the introduction of clinical guidelines for the management of the targeted chronic diseases facilitated by the necessary model of organizational changes.</p> <p>Conclusion</p> <p>Health planners and policy makers need to be aware of the potential use of certain theoretical models and applied methodology as well as inexpensive tools that may be suitably tailored to the local needs, in order to effectively design quality improvement interventions in primary care settings.</p
First results from the CERN Axion Solar Telescope (CAST)
Hypothetical axion-like particles with a two-photon interaction would be
produced in the Sun by the Primakoff process. In a laboratory magnetic field
(``axion helioscope'') they would be transformed into X-rays with energies of a
few keV. Using a decommissioned LHC test magnet, CAST has been running for
about 6 months during 2003. The first results from the analysis of these data
are presented here. No signal above background was observed, implying an upper
limit to the axion-photon coupling < 1.16 10^{-10} GeV^-1 at 95% CL for m_a
<~0.02 eV. This limit is comparable to the limit from stellar energy-loss
arguments and considerably more restrictive than any previous experiment in
this axion mass range.Comment: 4 pages, accepted by PRL. Final version after the referees comment
Search for CP Violation in the Decay Z -> b (b bar) g
About three million hadronic decays of the Z collected by ALEPH in the years
1991-1994 are used to search for anomalous CP violation beyond the Standard
Model in the decay Z -> b \bar{b} g. The study is performed by analyzing
angular correlations between the two quarks and the gluon in three-jet events
and by measuring the differential two-jet rate. No signal of CP violation is
found. For the combinations of anomalous CP violating couplings, and , limits of \hat{h}_b < 0.59h^{\ast}_{b} < 3.02$ are given at 95\% CL.Comment: 8 pages, 1 postscript figure, uses here.sty, epsfig.st
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