226 research outputs found
Pad\'e Approximants and Resonance Poles
Based on the mathematically well defined Pad\'e Theory, a theoretically safe
new procedure for the extraction of the pole mass and width of a resonance is
proposed. In particular, thanks to the Montessus de Ballore theorem we are able
to unfold the Second Riemann Sheet of an amplitude to search for the position
of the resonant pole in the complex plane. The method is systematic and
provides a model-independent treatment of the prediction and the corresponding
errors of the approximation.Comment: 12 pages, 17 figure
Some Remarks on the Pade Unitarization of Low-Energy Amplitudes
We present a critical analysis of Pade-based methods for the unitarization of
low energy amplitudes. We show that the use of certain Pade Approximants to
describe the resonance region may lead to inaccurate determinations. In
particular, we find that in the Linear Sigma Model the unitarization of the low
energy amplitude through the inverse amplitude method produces essentially
incorrect results for the mass and width of the sigma. Alternative sequences of
Pades are studied and we find that the diagonal sequences (i.e., [N/N]) have
much better convergence properties.Comment: 12 pages, 4 fig
Analytic Reconstruction of heavy-quark two-point functions at O(\alpha_s^3)
Using a method previously developed, based on the Mellin-Barnes transform, we
reconstruct the two-point correlators in the vector, axial, scalar and
pseudoscalar channels from the Taylor expansion at q^2=0, the threshold
expansion at q^2=4m^2 and the OPE at q^2\rightarrow -\infty, where m is the
heavy quark mass. The reconstruction is analytic and systematic and is
controlled by an error function which becomes smaller as more terms in those
expansions are known.Comment: 19 pages, 11 figure
Vector Meson Dominance as a first step in a systematic approximation: the pion vector form factor
Pade Approximants can be used to go beyond Vector Meson Dominance in a
systematic approximation. We illustrate this fact with the case of the pion
vector form factor and extract values for the first two coefficients of its
Taylor expansion. Pade Approximants are shown to be a useful and simple tool
for incorporating high-energy information, allowing an improved determination
of these Taylor coefficients.Comment: 13 pages, 7 figure
Familial amyloid polyneuropathy associated with TTRSer50Arg mutation in two Iberian families presenting a novel single base change in the mutant gene
Amyloid. 2007 Jun;14(2):147-52.
Familial amyloid polyneuropathy associated with TTRSer50Arg mutation in two Iberian families presenting a novel single base change in the mutant gene.
Munar-Qués M, Masjuan J, Coelho T, Moreira P, Viader-Farré C, Saraiva MJ.
Grupo de Estudio de la PAF, Plaza Olivar 5, 07002 Palma de Mallorca, Majorca, Spain. [email protected]
Abstract
We present two families, from Spain and Portugal, with familial amyloid polyneuropathy (FAP) associated with the mutation TTRSer50Arg. This mutation was first described in two Japanese patients from independent families and later in a French-Italian patient and a Vietnamese family. The two families presented here, are the first to be diagnosed with this mutation in the Iberian Peninsula. In the patients of both families, FAP was very aggressive as they rapidly developed multiple symptoms with progressive deterioration; we emphasize the presence of severe orthostatic hypotension in the Spanish proband which confined him to a wheelchair. This proband was the first patient with this mutation to have undergone liver transplantation and results were encouraging. The mutation was detected in four patients and one disease-free relative by DNA sequencing of exon 3 and induced mutation restriction analysis. The most outstanding feature was the single base transversion A to C in codon 50 (CGT instead of AGT), whereas in both Japanese patients and the French-Italian patient it was T to G (AGG instead of AGT). To our knowledge only six FAP mutations with more than one single nucleotide mutation for the same codon have been reported to date.
PMID: 17577688 [PubMed - indexed for MEDLINE
Light Meson Dynamics Workshop. Mini proceedings
The mini-proceedings of the Light Meson Dynamics Workshop held in Mainz from
February 10th to 12th, 2014, are presented. The web page of the conference,
which contains all talks, can be found at
https://indico.cern.ch/event/287442/overview .Comment: 46 pages, 17 contributions. Editors: W. Gradl, P. Masjuan, M.
Ostrick, and S. Schere
Optimization of treatment with interferon beta in multiple sclerosis. Usefulness of automatic system application criteria
<p>Abstract</p> <p>Background</p> <p>A software based tool has been developed (Optem) to allow automatize the recommendations of the Canadian Multiple Sclerosis Working Group for optimizing MS treatment in order to avoid subjective interpretation.</p> <p>Methods</p> <p>Treatment Optimization Recommendations (TORs) were applied to our database of patients treated with IFN β1a IM. Patient data were assessed during year 1 for disease activity, and patients were assigned to 2 groups according to TOR: "change treatment" (CH) and "no change treatment" (NCH). These assessments were then compared to observed clinical outcomes for disease activity over the following years.</p> <p>Results</p> <p>We have data on 55 patients. The "change treatment" status was assigned to 22 patients, and "no change treatment" to 33 patients. The estimated sensitivity and specificity according to last visit status were 73.9% and 84.4%. During the following years, the Relapse Rate was always higher in the "change treatment" group than in the "no change treatment" group (5 y; CH: 0.7, NCH: 0.07; p < 0.001, 12 m – last visit; CH: 0.536, NCH: 0.34). We obtained the same results with the EDSS (4 y; CH: 3.53, NCH: 2.55, annual progression rate in 12 m – last visit; CH: 0.29, NCH: 0.13).</p> <p>Conclusion</p> <p>Applying TOR at the first year of therapy allowed accurate prediction of continued disease activity in relapses and disability progression.</p
Constraining the Hadronic Contributions to the Muon Anomalous Magnetic Moment
The mini-proceedings of the Workshop on "Constraining the hadronic
contributions to the muon anomalous magnetic moment" which included the "13th
meeting of the Radio MonteCarLow WG" and the "Satellite meeting R-Measurements
at BES-III" held in Trento from April 10th to 12th, 2013, are presented. This
collaboration meeting aims to bring together the experimental e+e- collider
communities from BaBar, Belle, BESIII, CMD2, KLOE, and SND, with theorists
working in the fields of meson transitions form factors, hadronic contributions
to (g-2)_\mu and effective fine structure constant, and development of Monte
Carlo generator and Radiative Corrections for precision e+e- and tau physics.Comment: 45 pages, 17 contributions. Editors: P. Masjuan and G. Venanzon
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