340 research outputs found
Chiral Dynamics of scalar mesons: radiative decay and in the medium through nuclear photoproduction
In order to assess the relevance of chiral dynamics in the scalar sector we
address two recent problems: radiative decay of the , for which there are
quite recent data from Frascati, and the modification of the
properties in the nuclear medium seen through the photoproduction
in nuclei.Comment: Talk given at the High Energy Physics Workshop "Scalar Mesons: an
Interesting Puzzle for QCD", Utica, New York, May 200
Radiative vector meson decay
We study the radiative , and decay into and taking into account mechanisms in which there
are two sequential vector-vector-pseudoscalar or
axial-vector--vector--pseudoscalar steps followed by the coupling of a vector
meson to the photon, considering the final state interaction of the two mesons.
Other mechanisms in which two kaons are produced through the same sequential
mechanisms or from vector meson decay into two kaons which undergo final state
interaction leading to the final pair of pions or , are also
considered. The results of the parameter free theory, together with the
theoretical uncertainties, are compared with the latest experimental results at
Frascati and Novosibirsk.Comment: Prepared for the 10th International Symposium on Meson-Nucleon
Physics and the Structure of the Nucleo
Decay of axial-vector mesons into VP and P
We propose a phenomenological Lagrangian for the decay of the SU(3) nonets of
the axial-vector mesons of into a vector meson and a
pseudoscalar constructed with tensor fields for the vector and axial-vector
mesons. The formulation leads to a good reproduction of the different decay
branching ratios and assuming vector meson dominance (VMD) it also leads to
good results for the radiative decay of the into pion and photon, and in
agreement with the structure proposed in the chiral tensor formulation of
radiative decay of axial-vector mesons. The two SU(3) parameters and the mixing
angle of and needed to give the physical and
resonances are also determined.Comment: 17 pages, 1 figure; version accepted in Phys. Rev.
Transmit Power Minimization for MIMO Systems of Exponential Average BER with Fixed Outage Probability
This document is the Accepted Manuscript version of the following article: Dian-Wu Yue, and Yichuang Sun, ‘Transmit Power Minimization for MIMO Systems of Exponential Average BER with Fixed Outage Probability’, Wireless Personal Communications, Vol. 90 (4): 1951-1970, first available online on 20 June 2016. Under embargo. Embargo end date: 20 June 2017. The final publication is available at Springer via https://link.springer.com/article/10.1007%2Fs11277-016-3432-4This paper is concerned with a wireless multiple-antenna system operating in multiple-input multiple-output (MIMO) fading channels with channel state information being known at both transmitter and receiver. By spatiotemporal subchannel selection and power control, it aims to minimize the average transmit power (ATP) of the MIMO system while achieving an exponential type of average bit error rate (BER) for each data stream. Under the constraints on each subchannel that individual outage probability and average BER are given, based on a traditional upper bound and a dynamic upper bound of Q function, two closed-form ATP expressions are derived, respectively, which can result in two different power allocation schemes. Numerical results are provided to validate the theoretical analysis, and show that the power allocation scheme with the dynamic upper bound can achieve more power savings than the one with the traditional upper bound.Peer reviewe
Final State Interactions in Hadronic D decays
We show that the large corrections due to final state interactions (FSI) in
the D^+\to \pi^-\pi^+\pi^+, D^+_s\to \pi^-\pi^+\pi^+, and D^+\to K^-\pi^+\pi^+
decays can be accounted for by invoking scattering amplitudes in agreement with
those derived from phase shifts studies. In this way, broad/overlapping
resonances in S-waves are properly treated and the phase motions of the
transition amplitudes are driven by the corresponding scattering matrix
elements determined in many other experiments. This is an important step
forward in resolving the puzzle of the FSI in these decays. We also discuss why
the \sigma and \kappa resonances, hardly visible in scattering experiments, are
much more prominent and clearly visible in these decays without destroying the
agreement with the experimental \pi\pi and K\pi low energy S-wave phase shifts.Comment: 22 pages, 6 figures, 5 tables. Minor changes. We extend the discusion
when quoting a reference and we include a new one. Some typos are fixe
Analytical characterisation and pathology
Sem PDF.The aim of this work was to determine the physico-chemical characteristics of the stained-glass windows into the 19th century of two mausoleums located in the city of Belém do Pará (Brazil), and to evaluate their state of conservation. The glass chemical composition was determined by WXRF and SEM/EDS. The samples' morphology and the microorganisms' identification were carried out by optical microscopy. The results indicated that the samples were soda-lime silicate glass, with approximately 70wt. % of SiO2, which contributed to the resistance of the stained glass to the weathering. The concentration of Na2O was normally twice the K2O, which contrasts with the composition of other panels produced during the same period, as reported in the literature. The biofilm is composed by cyanobacteria and rotifers. Overall, the panels analysed were in a good state of conservation, despite their exposure to tropical climate conditions for more than a century with no preventive measures whatsoever.publishersversionpublishe
Percepción de la información recibida en los pacientes con síndrome de cushing y riesgo cardiovascular
El síndrome de Cushing (SC) es una enfermedad rara caracterizada por una hipersecreción de cortisol. La principal causa de morbi y mortalidad en el SC es la enfermedad cardiovascular. Objetivos generales: el objetivo fue evaluar la percepción del paciente con SC sobre la información recibida en aspectos concretos de la patología y hábitos de vida en un seguimiento realizado entre 2008 al 2009. Material y método: estudio observacional descriptivo desarrollado en la Unidad de Enfermedades Hipofisarias del Centro de Investigación de enfermedades Raras (CIBERER 747) sobre 30 pacientes visitados en el dispensario de endocrinología por SC. La población era de 60 pacientes diagnosticados de SC. La recogida de datos se realizó a través de un cuestionario ad-hoc, contemplando aspectos referentes a la información recibida sobre su patología en las siguientes áreas: SC, síntomas, signos, tratamiento, pruebas complementarias, tratamiento, complicaciones, factores de riesgo, hábitos de vida nutricional, deseo sexual, actividad física y descanso. Se evaluó a través de la escala de Likert siendo 0 ninguna información y 10 la información máxima recibida. Resultados: la puntuación superior a 5 en la escala de Likert, suficientemente informados, hace referencia a aspectos generales de su patología (88%), complicaciones (60%) y tratamiento (80%), los valores inferiores a 5, bastante o totalmente desinformados, corresponden a áreas especificas de enfermería, factores de riesgo (76%), hábitos de vida (82%), nutricionales (78%), sexuales (97%), actividad física (93%) y descanso (100%). Conclusiones: la percepción del paciente sobre la información recibida en algunas áreas específicas de enfermería es insuficiente o inexistente
decay within unitarized chiral perturbation theory
We improve the calculations of the decay
within the context of meson chiral lagrangians. We use a chiral unitary
approach for the meson-meson interaction, thus generating the
resonance and fixing the longstanding sign ambiguity on its contribution. This
also allows us to calculate the loops with one vector meson exchange, thus
removing a former source of uncertainty. In addition we ensure the consistency
of the approach with other processes. First, by using vector meson dominance
couplings normalized to agree with radiative vector meson decays. And, second,
by checking the consistency of the calculations with the related reaction. We find an decay width
of eV, in clear disagreement with published data but in
remarkable agreement with the most recent measurement.Comment: 15 pages, 10 figures, published versio
No evidence of SARS-CoV-2 infection in wild mink (Mustela lutreola and neogale vison) from northern Spain during the first two years of pandemic
The impact of the SARS-CoV-2 pandemic on wildlife is largely unevaluated, and extended surveillance of animal species is needed to reach a consensus on the role of animals in the emergence and maintenance of SARS-CoV-2. This infection has been detected in farmed and domestic animals and wild animals, mainly in captivity. The interactions or shared resources with wildlife could represent a potential transmission pathway for the SARS-CoV-2 spill over to other wild species and could lead to health consequences or the establishment of new reservoirs in susceptible hosts. This study evaluated the presence of SARS-CoV-2 in European mink (Mustela lutreola) and American mink (Neogale vison) in Spain by enzyme-linked immunosorbent assay (ELISA) using the receptor binding domain (RBD) of Spike antigen in serum samples and/or by RT-qPCR assays in oropharyngeal and rectal swabs. From January 2020 to February 2022, a total of 162 animals (127 European mink and 35 American mink) with no evidence of SARS-CoV-2 infection were included in the study. Antibodies against the SARS-CoV-2 were not found in the serum samples analysed (n = 126), nor was the virus amplified by RT-qPCR (n = 160 swabs). Our results suggest that the potential role of wild mink and the European mink bred in captivity and released to the wild as dispersers of SARS-CoV-2 is so far low. However, wildlife surveillance for early detection of human and animal risks should be continued. In this sense, epidemiological monitoring measures, including serology and molecular analysis, are necessary
Prevention of ventilator-associated pneumonia: the multimodal approach of the spanish ICU pneumonia zero program.
Objectives:
The “Pneumonia Zero” project is a nationwide multimodal intervention based on the simultaneous implementation of a comprehensive evidence-based bundle measures to prevent ventilator-associated pneumonia in critically ill patients admitted to the ICU.
Design:
Prospective, interventional, and multicenter study.
Setting:
A total of 181 ICUs throughout Spain.
Patients:
All patients admitted for more than 24 hours to the participating ICUs between April 1, 2011, and December 31, 2012.
Intervention:
Ten ventilator-associated pneumonia prevention measures were implemented (seven were mandatory and three highly recommended). The database of the National ICU-Acquired Infections Surveillance Study (Estudio Nacional de Vigilancia de Infecciones Nosocomiales [ENVIN]) was used for data collection. Ventilator-associated pneumonia rate was expressed as incidence density per 1,000 ventilator days. Ventilator-associated pneumonia rates from the incorporation of the ICUs to the project, every 3 months, were compared with data of the ENVIN registry (April–June 2010) as the baseline period. Ventilator-associated pneumonia rates were adjusted by characteristics of the hospital, including size, type (public or private), and teaching (postgraduate) or university-affiliated (undergraduate) status.
Measurements and Main Results:
The 181 participating ICUs accounted for 75% of all ICUs in Spain. In a total of 171,237 ICU admissions, an artificial airway was present on 505,802 days (50.0% of days of stay in the ICU). A total of 3,474 ventilator-associated pneumonia episodes were diagnosed in 3,186 patients. The adjusted ventilator-associated pneumonia incidence density rate decreased from 9.83 (95% CI, 8.42–11.48) per 1,000 ventilator days in the baseline period to 4.34 (95% CI, 3.22–5.84) after 19–21 months of participation.
Conclusions:
Implementation of the bundle measures included in the “Pneumonia Zero” project resulted in a significant reduction of more than 50% of the incidence of ventilator-associated pneumonia in Spanish ICUs. This reduction was sustained 21 months after implementation
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