8,400 research outputs found
Quasiparticle operators with non-Abelian braiding statistics
We study the gauge invariant fermions in the fermion coset representation of
Wess-Zumino-Witten models which create, by construction, the physical
excitations (quasiparticles) of the theory. We show that they provide an
explicit holomorphic factorization of Wess-Zumino-Witten primaries
and satisfy non-Abelian braiding relations.Comment: 13 pages, no figures, final version to appear in Physics Letters
Effect of time of annealing on gas permeation through coextruded linear low-density polyethylene (LLDPE) films
[EN] The effect of annealing on the permeation of oxygen, nitrogen, and carbon dioxide through
coextruded linear low-density polyethylene (LLDPE) films is studied. The results indicate that the
permeability coefficient P of nitrogen does not show a definite dependence on the time of annealing, ta,
whereas for the other gases this parameter increases with ta. The analysis of the variation of the diffusion
coefficient of O2 and N2 with ta indicates that D undergoes a sharp decrease from ta ) 0 to ta ) 2 h, but
for larger times of annealing the diffusion parameter only undergoes a slight diminution; on the contrary,
the diffusion coefficient of CO2 gradually decreases with increasing ta. The fact that annealing increases
the solubility of the gases in the polymer films suggests that thermal treatments may favor the formation
of microcavities or molecular packing defects in the crystalline amorphous interface that can accommodate
individual site molecules without disturbing the natural dissolution process in the rubbery region of the
polymer matrix. Finally, free volume theories are not sensitive enough to interpret the effect of annealing
on the permeation characteristics of coextruded LLDPE films.This work was supported by the DGICYT through Grant PB95-0134-C02.Compañ Moreno, V.; Andrio, A.; Lopez, ML.; Alvarez, C.; Riande, E. (1997). Effect of time of annealing on gas permeation through coextruded linear low-density polyethylene (LLDPE) films. Macromolecules. 30:3317-3322. http://hdl.handle.net/10251/147741S331733223
Self-dual Ginzburg-Landau vortices in a disk
We study the properties of the Ginzburg-Laundau model in the self-dual point
for a two-dimensional finite system . By a numerical calculation we analyze the
solutions of the Euler-Lagrange equations for a cylindrically symmetric ansatz.
We also study the self-dual equations for this case. We find that the minimal
energy configurations are not given by the Bogomol'nyi equations but by
solutions to the Euler Lagrange ones. With a simple approximation scheme we
reproduce the result of the numerical calculation.Comment: 8 pages, 4 figures, RevTex macro
Prevalence and trends of thinness, overweight and obesity among children and adolescents aged 3-18 years across Europe: a protocol for a systematic review and meta-analysis
Introduction Increasing prevalence of both thinness and excess weight during childhood and adolescence is a significant public health issue because of short-term health consequences and long-term tracking of weight status. Monitoring weight status in Europe may serve to identify countries and regions where rates of these disorders are either slowing down or increasing to evaluate recent policies aimed at appropriate body weight, and to direct future interventions. This study protocol provides a standardised and transparent methodology to improve estimating trends of thinness, overweight and obesity in children aged 3-18 years and adolescents across the European region between 2000 and 2017. Methods and analysis This protocol is guided by the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) and the Cochrane Collaboration Handbook. To identify relevant studies, a search will be conducted in MEDLINE, EMBASE, Cochrane Library, CINAHL and Web of Science databases. From the selected studies, relevant references will be screened as supplemental sources. Finally, open search in websites from health institutions will be conducted to identify weight status data not published in scientific journals. Cross-sectional, follow-up studies and panel surveys reporting weight status (objectively measured height and weight) according to the International Obesity Task Force criteria, and written in English or Spanish will be included. Subgroup analyses will be carried out by gender, age, study year and country or European region. Discussion This study will provide a comprehensive description of weight status of children and adolescents across Europe from 2000 to 2017. The results will be disseminated in a peer-reviewed journal. This study will use data exclusively from published research or institutional literature, so institutional ethical approval is not required
Medición de temperatura de no contacto de superficies sólidas irradiadas por energÃa solar concentrada mediante obturación con pelÃculas PDLC: una nueva metodologÃa
CIES2020 - XVII Congresso Ibérico e XIII Congresso Ibero-americano de Energia SolarRESUMEN: En este trabajo se presenta una nueva metodologÃa para la medición de la temperatura de superficies sólidas expuestas a radiación solar concentrada, mediante la técnica de obturación utilizando una pelÃcula PDLC. Esta nueva metodologÃa permitirá separar el espectro de radiación emitido por la muestra del espectro de radiación reflejado, y permitirá medir solamente la temperatura referente a la potencia emisiva de la muestra, utilizando un pirómetro monocromático en un horno solar. Se describe el arreglo experimental que se propone para implementar esta metodologÃa. El arreglo consistente de un horno solar (MHS IER-UNAM), de una ventana de pelÃcula PDLC y de una cámara de medición de temperatura. Se muestran las transmitancias de la pelÃcula PDLC destacando la pertinencia de su uso para esta aplicación solar. La calibración del pirómetro monocromático arrojó un aff-set del -4% del valor nominal. La respuesta térmica de la muestra de grafito que se usará como referencia arrojó valores entre 502.6 y 1747.8 segundos dependiendo del proceso de calentamiento o enfriamiento.ABSTRACT: In this work, a new methodology for measuring the temperature of solid surfaces exposed to concentrated solar radiation, using the shutter technique and a PDLC film is presented. This new methodology will allow the separation of the radiation spectrum emitted by the sample from the reflected radiation spectrum, and it will allow only the temperature referring to the emissive power of the sample to be measured, using a monochromatic pyrometer in a solar furnace. The experimental arrangement that is proposed to implement this methodology is described. The arrangement consisting of a solar furnace (MHS IER-UNAM), a PDLC film window and a temperature measurement chamber. The transmittances of the PDLC film are shown, highlighting the relevance of its use for this solar application. The monochrome pyrometer calibration yielded an aff-set of -4% of the nominal value. The thermal response of the graphite sample to be used as a reference yielded values between 502.6 and 1747.8 seconds depending on the heating or cooling process.info:eu-repo/semantics/publishedVersio
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Comparison of thermistor linearization techniques for accurate temperature measurement in phase change materials
Alternate energy technologies are developing rapidly in the recent years. A significant part of this trend is the development of different phase change materials (PCMs). Proper utilization of PCMs requires accurate thermal characterization. There are several methodologies used in this field. This paper stresses the importance of accurate temperature measurements during the implementation of T-history method. Since the temperature sensor size is also important thermistors have been selected as the sensing modality. Two thermistor linearization techniques, one based on Wheatstone bridge and the other based on simple serial-parallel resistor connection, are compared in terms of achievable temperature accuracy through consideration of both, nonlinearity and self-heating errors. Proper calibration was performed before T-history measurement of RT21 (RUBITHERM® GmbH) PCM. Measurement results suggest that the utilization of serial-parallel resistor connection gives better accuracy (less than ±0.1°C) in comparison with the Wheatstone bridge based configuration (up to ±1.5°C)
Constraints on Supersymmetric Theories from
In the absence of any additional assumption it is natural to conjecture that
sizeable flavour-mixing mass entries, , may appear in the mass
matrices of the scalars of the MSSM, i.e. . This flavour
violation can still be reconciled with the experiment if the gaugino mass,
, is large enough, leading to a {\em gaugino dominance} framework
(i.e. ), which permits a remarkably model--independent
analysis. We study this possibility focussing our attention on the
decay. In this way we obtain very strong and general
constraints, in particular \frac{M_{1/2}^2}{\Delta m}\simgt 34\ {\rm TeV}. On
the other hand, we show that our analysis and results remain valid for values
of much larger than , namely for \frac{\Delta
m^2}{m^2}\simgt \frac{m^2} {10\ {\rm TeV^2}}, thus extending enormously their
scope of application. Finally, we discuss the implications for superstring
scenarios.Comment: 12 pages, Latex, 5 figures as uuencoded compressed postscript files,
uses psfig.st
Lattice Perturbation Theory in Noncommutative Geometry and Parity Anomaly in 3D Noncommutative QED
We formulate lattice perturbation theory for gauge theories in noncommutative
geometry. We apply it to three-dimensional noncommutative QED and calculate the
effective action induced by Dirac fermions. In particular "parity invariance"
of a massless theory receives an anomaly expressed by the noncommutative
Chern-Simons action. The coefficient of the anomaly is labelled by an integer
depending on the lattice action, which is a noncommutative counterpart of the
phenomenon known in the commutative theory. The parity anomaly can also be
obtained using Ginsparg-Wilson fermions, where the masslessness is guaranteed
at finite lattice spacing. This suggests a natural definition of the
lattice-regularized Chern-Simons theory on a noncommutative torus, which could
enable nonperturbative studies of quantum Hall systems.Comment: 31 pages. LaTeX, feynmf. Minor changes, references added and typos
corrected. Final version published in JHE
Effects of an Extensively Hydrolyzed Formula Supplemented with Two Human Milk Oligosaccharides on Growth, Tolerability, Safety and Infection Risk in Infants with Cow’s Milk Protein Allergy: A Randomized, Multi-Center Trial
This randomized clinical trial (Registration: NCT03085134) assessed if an extensively hydrolyzed formula (EHF) supplemented with two human milk oligosaccharides (HMO) and reduced protein content (2.20 g/100 kcal) supports normal growth in infants with cow’s milk protein allergy (CMPA). Secondary outcomes were gastrointestinal tolerability, safety, and effect on infections. Nonbreastfed infants aged 0–6 months with CMPA were enrolled. Body weight, length, and head circumference were measured monthly for 4 months (primary study endpoint), after 6 months, and at the age of 12 months. Of 200 infants screened, 194 (mean age 3.2 months) were randomized. At the 4-month follow-up, daily weight gain for the test formula was noninferior to the control formula; p < 0.005. There were no significant group differences in anthropometric parameters. Both formulas were safe and well tolerated. Infants in the HMO group had a statistically significant reduction in the frequency of upper respiratory tract infections and a lower incidence of ear infections at 12 months (per protocol analysis). The relative risk of lower respiratory tract and gastrointestinal infections was reduced by 30–40%, but this was not statistically significant due to sample size limitations. In summary, the HMO-supplemented formula supports normal growth in infants with CMPA and suggests a protective effect against respiratory and ear infections in the first year of life
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