5,884 research outputs found
Charge and Magnetic Moment of the Neutrino in the Background Field Method and in the Linear R_xi^L Gauge
We present a computation of the charge and the magnetic moment of the
neutrino in the recently developed electro-weak Background Field Method and in
the linear gauge. First, we deduce a formal Ward-Takahashi identity
which implies the immediate cancellation of the neutrino electric charge. This
Ward-Takahashi identity is as simple as that for QED. The computation of the
(proper and improper) one loop vertex diagrams contributing to the neutrino
electric charge is also presented in an arbitrary gauge, checking in this way
the Ward-Takahashi identity previously obtained. Finally, the calculation of
the magnetic moment of the neutrino, in the minimal extension of the Standard
Model with massive Dirac neutrinos, is presented, showing its gauge parameter
and gauge structure independence explicitly.Comment: Latex, 19 pages, 9 PS and 10 EPS figures. One reference added.
Appendix B modified and Appendices C-E eliminated. To be published in Eur.
Phys. J.
Migraine, Fibromyalgia, and Depression among People with IBS: A Prevalence Study
BACKGROUND. Case descriptions suggest IBS patients are more likely to have other disorders, including migraine, fibromyalgia, and depression. We sought to examine the prevalence of these conditions in cohorts of people with and without IBS. METHODS. The source of data was a large U.S. health plan from January 1, 1996 though June 30, 2002. We identified all people with a medical claim associated with an ICD-9 code for IBS. A non-IBS cohort was a random sample of people with an ICD-9 code for routine medical care. In the cohorts, we identified all claims for migraine, depression, and fibromyalgia. We estimated the prevalence odds ratios (PORs) of each of the three conditions using the Mantel-Haenszel method. We conducted quantitative sensitivity analyses to quantify the impact of residual confounding and in differential outcome identification. RESULTS. We identified 97,593 people in the IBS cohort, and a random sample of 27,402 people to compose the non-IBS comparison cohort. With adjustment, there was a 60% higher odds in the IBS cohort of having any one of the three disorders relative to the comparison cohort (POR 1.6, 95% CI 1.5 – 1.7). There was a 40% higher odds of depression in the IBS cohort (POR 1.4, 95% CI 1.3 – 1.4). The PORs for fibromyalgia and migraine were similar (POR for fibromyalgia 1.8, 95% CI 1.7 – 1.9; POR for migraine 1.6, 95% CI 1.4 – 1.7). Differential prevalence of an unmeasured confounder, or imperfect sensitivity or specificity of outcome detection would have impacted the observed results. CONCLUSION. People in the IBS cohort had a 40% to 80% higher prevalence odds of migraine, fibromyalgia, and depression
Tightening the belt: Constraining the mass and evolution in SDC335
Recent ALMA observations identified one of the most massive star-forming
cores yet observed in the Milky Way; SDC335-MM1, within the infrared dark cloud
SDC335.579-0.292. Along with an accompanying core MM2, SDC335 appears to be in
the early stages of its star formation process. In this paper we aim to
constrain the properties of the stars forming within these two massive
millimetre sources. Observations of SDC335 at 6, 8, 23 and 25GHz were made with
the ATCA. We report the results of these continuum measurements, which combined
with archival data, allow us to build and analyse the spectral energy
distributions (SEDs) of the compact sources in SDC335. Three HCHII regions
within SDC335 are identified, two within the MM1 core. For each HCHII region, a
free-free emission curve is fit to the data allowing the derivation of the
sources' emission measure, ionising photon flux and electron density. Using
these physical properties we assign each HCHII region a ZAMS spectral type,
finding two protostars with characteristics of spectral type B1.5 and one with
a lower limit of B1-B1.5. Ancillary data from infrared to mm wavelength are
used to construct free-free component subtracted SEDs for the mm-cores,
allowing calculation of the bolometric luminosities and revision of the
previous gas mass estimates. The measured luminosities for the two mm-cores are
lower than expected from accreting sources displaying characteristics of the
ZAMS spectral type assigned to them. The protostars are still actively
accreting, suggesting that a mechanism is limiting the accretion luminosity, we
present the case for two different mechanisms capable of causing this. Finally,
using the ZAMS mass values as lower limit constraints, a final stellar
population for SDC335 was synthesised finding SDC335 is likely to be in the
process of forming a stellar cluster comparable to the Trapezium Cluster and
NGC6334 I(N).Comment: 10 pages, 5 figures. Accepted for publication in A&
Vacuum Polarization by a Magnetic Flux Tube at Finite Temperature in the Cosmic String Spacetime
In this paper we analyse the effect produced by the temperature in the vacuum
polarization associated with charged massless scalar field in the presence of
magnetic flux tube in the cosmic string spacetime. Three different
configurations of magnetic fields are taken into account: a homogeneous
field inside the tube, a field proportional to and a
cylindrical shell with -function. In these three cases, the axis of the
infinitely long tube of radius coincides with the cosmic string. Because
the complexity of this analysis in the region inside the tube, we consider the
thermal effect in the region outside. In order to develop this analysis, we
construct the thermal Green function associated with this system for the three
above mentioned situations considering points in the region outside the tube.
We explicitly calculate in the high-temperature limit, the thermal average of
the field square and the energy-momentum tensor.Comment: 16 pages, 1 figur
A semantic web service-based architecture for the interoperability of e-government services
We propose a semantically-enhanced architecture to address the issues of interoperability and service integration in e-government web information systems. An architecture for a life event portal based on Semantic Web Services (SWS) is described. The architecture includes loosely-coupled modules organized in three distinct layers: User Interaction, Middleware and Web Services. The Middleware provides the semantic infrastructure for ontologies and SWS. In particular a conceptual model for integrating domain knowledge (Life Event Ontology), application knowledge (E-government Ontology) and service description (Service Ontology) is defined. The model has been applied to a use case scenario in e-government and the results of a system prototype have been reported to demonstrate some relevant features of the proposed approach
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