171 research outputs found
\pi\pi, K\pi and \pi N potential scattering and a prediction of a narrow \sigma meson resonance
Low energy scattering and bound state properties of the \pi N, \pi\pi and
K\pi systems are studied as coupled channel problems using inversion potentials
of phase shift data. In a first step we apply the potential model to explain
recent measurements of pionic hydrogen shift and width. Secondly, predictions
of the model for pionium lifetime and shift confirm a well known and widely
used effective range expression. Thirdly, as extension of this confirmation, we
predict an unexpected medium effect of the pionium lifetime which shortens by
several orders of magnitude. The \sigma meson shows a narrow resonance
structure as a function of the medium modified mass with the implication of
being essentially energy independent. Similarly, we see this medium resonance
effect realized for the K\pi system. To support our findings we present also
results for the \rho meson and the \Delta(1232) resonance.Comment: 42 pages, 17 PS figures, REFTeX, epsfig.sty needed, submitted to
Phys. Re
Energy and decay width of the pi-K atom
The energy and decay width of the pi-K atom are evaluated in the framework of
the quasipotential-constraint theory approach. The main electromagnetic and
isospin symmetry breaking corrections to the lowest-order formulas for the
energy shift from the Coulomb binding energy and for the decay width are
calculated. They are estimated to be of the order of a few per cent. We display
formulas to extract the strong interaction S-wave pi-K scattering lengths from
future experimental data concerning the pi-K atom.Comment: 37 pages, 5 figures, uses Axodra
A Study of Cosmic Ray Composition in the Knee Region using Multiple Muon Events in the Soudan 2 Detector
Deep underground muon events recorded by the Soudan 2 detector, located at a
depth of 2100 meters of water equivalent, have been used to infer the nuclear
composition of cosmic rays in the "knee" region of the cosmic ray energy
spectrum. The observed muon multiplicity distribution favors a composition
model with a substantial proton content in the energy region 800,000 -
13,000,000 GeV/nucleus.Comment: 38 pages including 11 figures, Latex, submitted to Physical Review
Determination of scattering lengths from measurement of atom lifetime
The DIRAC experiment at CERN has achieved a sizeable production of
atoms and has significantly improved the precision on its lifetime
determination. From a sample of 21227 atomic pairs, a 4% measurement of the
S-wave scattering length difference
has been attained, providing an important test of Chiral Perturbation Theory.Comment: 6 pages, 6 figure
(Pi+Pi-) Atom in Chiral Perturbation Theory
Hadronic (Pi+Pi-) atom is studied in the relativistic perturbative approach
based on the Bethe-Salpeter equation. The general expression for the atom
lifetime is derived. Lowest-order corrections to the relativistic Deser-type
formula for the atom lifetime are evaluated within the Chiral Perturbation
Theory.Comment: 36 pages, LaTeX-file (revtex.sty
Significant differences in the use of healthcare resources of native-born and foreign born in Spain
<p>Abstract</p> <p>Background</p> <p>In the last decade, the number of foreign residents in Spain has doubled and it has become one of the countries in the European Union with the highest number of immigrants There is no doubt that the health of the immigrant population has become a relevant subject from the point of view of public healthcare. Our study aimed at describing the potential inequalities in the use of healthcare resources and in the lifestyles of the resident immigrant population of Spain.</p> <p>Methods</p> <p>Cross-sectional, epidemiological study from the Spanish National Health Survey (NHS) in 2006, from the Ministry of Health and Consumer Affairs. We have worked with individualized secondary data, collected in the Spanish National Health Survey carried out in 2006 and 2007 (SNHS-06), from the Ministry of Health and Consumer Affairs. The format of the SNHS-06 has been adapted to the requirements of the European project for the carrying out of health surveys.</p> <p>Results</p> <p>The economic immigrant population resident in Spain, present diseases that are similar to those of the indigenous population. The immigrant population shows significantly lower values in the consumption of alcohol, tobacco and physical activity (OR = 0.76; CI 95%: 0.65–0.89, they nonetheless perceive their health condition as worse than that reported by the autochthonous population (OR = 1.63, CI 95%: 1.34–1.97). The probability of the immigrant population using emergency services in the last 12 months was significantly greater than that of the autochthonous population (OR = 1.31, CI 95%: 1.12–1.54). This situation repeats itself when analyzing hospitalization data, with values of probability of being hospitalized greater among immigrants (OR = 1.39, CI 95%: 1.07–1.81).</p> <p>Conclusion</p> <p>The economic immigrants have better parameters in relation to lifestyles, but they have a poor perception of their health. Despite the fact that immigrant population shows higher percentages of emergency attendance and hospitalization than the indigenous population, with respect to the use of healthcare resources, their usage of healthcare resources such as drugs, influenza vaccinations or visits to the dentist is lower.</p
Feasibility and validation of trans-valvular flow derived by four-dimensional flow cardiovascular magnetic resonance imaging in patients with atrial fibrillation
Background: Four-dimensional (4D) flow cardiovascular magnetic resonance imaging (MRI) is an emerging technique used for intra-cardiac blood flow assessment. The role of 4D flow cardiovascular MRI in the assessment of trans-valvular flow in patients with atrial fibrillation (AF) has not previously been assessed. The purpose of this study was to assess the feasibility, image quality, and internal validity of 4D flow cardiovascular MRI in the quantification of trans-valvular flow in patients with AF.
Methods: Patients with AF and healthy controls in sinus rhythm underwent cardiovascular MRI, including 4D flow studies. Quality assurance checks were done on the raw data and streamlines. Consistency was investigated by trans-valvular flow assessment between the mitral valve (MV) and the aortic valve (AV).
Results: Eight patients with AF (88% male, mean age 62±13 years, mean heart rate (HR) 83±16 beats per minute (bpm)) were included and compared with ten healthy controls (70% male, mean age 41±20 years, mean HR 68.5±9 bpm). All scans were of either good quality with minimal blurring artefacts, or excellent quality with no artefacts. No significant bias was observed between the AV and MV stroke volumes in either healthy controls (–4.8, 95% CI –15.64 to 6.04; P=0.34) or in patients with AF (1.64, 95% CI –4.7 to 7.94; P=0.56). A significant correlation was demonstrated between MV and AV stroke volumes in both healthy controls (r=0.87, 95% CI 0.52 to 0.97; P=0.001) and in AF patients (r=0.82, 95% CI 0.26 to 0.97; P=0.01).
Conclusions: In patients with AF, 4D flow cardiovascular MRI is feasible with good image quality, allowing for quantification of trans-valvular flow
A Spatial Analysis of County-level Variation in Syphilis and Gonorrhea in Guangdong Province, China
Sexually transmitted infections (STI) have made a resurgence in many rapidly developing regions of southern China, but there is little understanding of the social changes that contribute to this spatial distribution of STI. This study examines county-level socio-demographic characteristics associated with syphilis and gonorrhea in Guangdong Province.This study uses linear regression and spatial lag regression to determine county-level (n = 97) socio-demographic characteristics associated with a greater burden of syphilis, gonorrhea, and a combined syphilis/gonorrhea index. Data were obtained from the 2005 China Population Census and published public health data. A range of socio-demographic variables including gross domestic product, the Gender Empowerment Measure, standard of living, education level, migrant population and employment are examined. Reported syphilis and gonorrhea cases are disproportionately clustered in the Pearl River Delta, the central region of Guangdong Province. A higher fraction of employed men among the adult population, higher fraction of divorced men among the adult population, and higher standard of living (based on water availability and people per room) are significantly associated with higher STI cases across all three models. Gross domestic product and gender inequality measures are not significant predictors of reported STI in these models.Although many ecological studies of STIs have found poverty to be associated with higher reported STI, this analysis found a greater number of reported syphilis cases in counties with a higher standard of living. Spatially targeted syphilis screening measures in regions with a higher standard of living may facilitate successful control efforts. This analysis also reinforces the importance of changing male sexual behaviors as part of a comprehensive response to syphilis control in China
DIRAC: A High Resolution Spectrometer for Pionium Detection
The DIRAC spectrometer has been commissioned at CERN with the aim of
detecting atoms produced by a 24 GeV/ high intensity proton
beam in thin foil targets. A challenging apparatus is required to cope with the
high interaction rates involved, the triggering of pion pairs with very low
relative momentum, and the measurement of the latter with resolution around 0.6
MeV/. The general characteristics of the apparatus are explained and each
part is described in some detail. The main features of the trigger system,
data-acquisition, monitoring and setup performances are also given.Comment: 49 pages, 37 figures. Figures 1, 2, 5 and 28 are removed because of
size limitations imposed by hep-ex. They don't offer essential information.
Latex class file 'elsart.cls' also provide
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