379 research outputs found
Similarity Maximization of a Scaled Aeroelastic Flight Demonstrator via Multidisciplinary Optimization
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143025/1/6.2017-0573.pd
Self-Determined Motivation and Competitive Anxiety in Athletes/Students: A Probabilistic Study Using Bayesian Networks
This study attempts to analyze the relationship between two key psychological variables associated with performance in sports – Self-Determined Motivation and Competitive Anxiety – through Bayesian Networks (BN) analysis. We analyzed 674 university students that are athletes from 44 universities that competed at the University Games in Mexico, with an average age of 21 years (SD = 2.07) and with a mean of 8.61 years’ (SD = 5.15) experience in sports. Methods: Regarding the data analysis, firstly, classification using the CHAID algorithm was carried out to determine the dependence links between variables; Secondly, a BN was developed to reduce the uncertainty in the relationships between the two key psychological variables. The validation of the BN revealed AUC values ranging from 0.5 to 0.92. Subsequently, various instantiations were performed with hypothetical values applied to the “bottom” variables. Results showed two probability trees that have extrinsic motivation and amotivation at the top, while the anxiety/activation due to worries about performance was at the bottom of the probabilities. The instantiations carried out support the existence of these probabilistic relationships, demonstrating their scarce influence on anxiety about competition generated by the intrinsic motivation, and the complex probabilistic effect of introjected and identified regulation regarding the appearance of anxiety due to worry about performance
Can we speak of a negative psychological tetrad in sports? A probabilistic Bayesian study on competitive sailing
INTRODUCTION: Researchers display an interest in studying aspects like the mental health of high-performance athletes; the dark side of sport, or the earliest attempts to study the so-called dark triad of personality in both initiation and high-performance athletes. Therefore, the objective of this paper is to determine the possible existence and magnitude of negative psychological aspects within a population of competition sailors and from a probabilistic point of view, using Bayesian Network analysis.
METHODS: The study was carried out on 235 semi-professional sailors of the 49er Class, aged between 16 and 52 years (M = 24.66; SD = 8.03).
RESULTS: The results show the existence of a Negative Tetrad-formed by achievement burnout, anxiety due to concentration disruption, amotivation and importance given to error-as a probabilistic product of the psychological variables studied: motivation, anxiety, burnout and fear of error.
CONCLUSION: These results, supported by Bayesian networks, show holistically the influence of the social context on the psychological and emotional well-being of the athlete during competition at sea
Medición y evaluación de valores en contenidos audiovisuales desde un abordaje interdisciplinar
El siguiente estudio interdisciplinar realizado por LAICOM (Laboratorio de Análisis Instrumental de la Comunicación, UAB), parte de la revisión del concepto de calidad comunicativa y formula un inventario de 26 valores para el ámbito iberoamericano, seleccionados aplicando el análisis de contenido a tres documentos de gran consenso social: "Carta de Derechos Humanos" (1948), "Constitución Federal de Brasil" (1988) y "Constitución Española" (1978). Los valores se han definido en sus dimensiones social, humana y educativa. Finalmente, se propone y valida un protocolo basado en test de recepción, capaz de medir y comparar la carga de valores transmitida en cualquier proceso de comunicación. El protocolo ha sido experimentado y corregido aplicándolo a 2 grupos de 10 expertos que evaluaron 4 spots publicitarios, con los que, luego, se organizaron sendos grupos de discusión.This interdisciplinary research, carried out by LAICOM reviews the concept quality communication and designs a 26 values glossary within the ibero-American context. Values are selected by applying a content analysis to 3 documents of feat social consensus: the "Human Rights Act" (1948), the "Federal Brazilian Constitution" (1988), and the "Spanish Constitution (1978); and are defined in three dimensions: human, social and education. Finally, a protocol is proposed and validated by a test of reception, which serves to measure and compare the load of values transmitted by any process of communication. This protocol is tested and corrected through two focus groups of communication experts (10 each), who first had to evaluate 4 TV ads and second discuss about results collected
Confidence limits of evolutionary synthesis models. IV Moving forward to a probabilistic formulation
Synthesis models predict the integrated properties of stellar populations.
Several problems exist in this field, mostly related to the fact that
integrated properties are distributed. To date, this aspect has been either
ignored (as in standard synthesis models, which are inherently deterministic)
or interpreted phenomenologically (as in Monte Carlo simulations, which
describe distributed properties rather than explain them). We approach
population synthesis as a problem in probability theory, in which stellar
luminosities are random variables extracted from the stellar luminosity
distribution function (sLDF). We derive the population LDF (pLDF) for clusters
of any size from the sLDF, obtaining the scale relations that link the sLDF to
the pLDF. We recover the predictions of standard synthesis models, which are
shown to compute the mean of the sLDF. We provide diagnostic diagrams and a
simplified recipe for testing the statistical richness of observed clusters,
thereby assessing whether standard synthesis models can be safely used or a
statistical treatment is mandatory. We also recover the predictions of Monte
Carlo simulations, with the additional bonus of being able to interpret them in
mathematical and physical terms. We give examples of problems that can be
addressed through our probabilistic formalism. Though still under development,
ours is a powerful approach to population synthesis. In an era of resolved
observations and pipelined analyses of large surveys, this paper is offered as
a signpost in the field of stellar populations.Comment: Accepted by A&A. Substantially modified with respect to the 1st
draft. 26 pages, 14 fig
Aeroelastic scaling of flying demonstrator: flutter matching
The traditional approach for the design of aeroelastically scaled models assumes that either there exists flow similarity between the full-size aircraft and the model, or that flow non-similarities have a negligible effect. However, when trying to reproduce the behavior of an airliner that flies at transonic conditions using a scaled model that flies at nearly-incompressible flow conditions, this assumption is no longer valid and both flutter speed and static aerodynamic loading are subject to large discrepancies. To address this issue, we present an optimization-based approach for wing planform design that matches the scaled flutter speeds and modes of the reference aircraft when the Mach number cannot be matched. This is achieved by minimizing the squared error between the full-size and scaled aerodynamic models. This method is validated using the Common Research Model wing at the reference aircraft Mach number. The error in flutter speed is computed using the same wing at model conditions, which are in the nearly-incompressible regime. Starting from the baseline wing, its planform is optimized to match the reference response despite different conditions, achieving a reduction of the error in the predicted flutter speed from 7.79% to 2.13%
On the Detectability of Lyman-alpha Emission in Star-forming Galaxies: The Role of Dust
Lyman-alpha is now widely used to investigate the galaxy formation and
evolution in the high redshift universe. However, without a rigorous
understanding of the processes which regulate the Lya escape fraction, physical
interpretations of high-z observations remain questionable. We examine six
nearby star-forming galaxies to disentangle the role of the dust from other
parameters such as gas kinematics, geometry and ISM morphology in the
obscuration of Ly-alpha. Thereby we aim to understand the Ly-a escape physics
and infer the implications for high-redshift studies. We use HST/ACS to produce
continuum-subtracted Lya maps, and ground-based observations (ESO/NTT and NOT)
to map the Halpha emission and the extinction E(B-V) in the gas phase derived
from the Balmer decrement Halpha/Hbeta. When large outflows are present, the
Lya emission appears not to correlate with the dust content, confirming the
role of the HI kinematics in the escape of Lya photons. In the case of a dense,
static HI covering, we observe a damped absorption with a declining
relationship between Lya and E(B-V). We found that the Lya escape fraction does
not exceed 10% in all our galaxies and is mostly about 3% or below. Finally,
because of the radiative transfer complexity of the Lya line, star formation
rate based on Lya luminosity is underestimated with respect to that derived
from UV luminosity. The failure of simple dust correction to recover the
intrinsic Lya/Ha ratio or the total star formation rate should prompt us to be
more cautious when interpreting high-z observations and related properties,
such as SFRs based on Lya alone. To this end we propose a more realistic
calibration for SFR(Lya) which accounts for dust attenuation and resonant
scattering effects via the Lya escape fraction.Comment: Accepted for publication in A&A, 19 pages, 15 figure
Modeling the ionizing spectra of H ii regions: individual stars versus stellar ensembles
Aims. We study how IMF sampling affects the ionizing flux and emission line
spectra of low mass stellar clusters. Methods. We performed 2 x 10^6 Monte
Carlo simulations of zero-age solar-metallicity stellar clusters covering the
20 - 10^6 Mo mass range. We study the distribution of cluster stellar masses,
Mclus, ionizing fluxes, Q(H0), and effective temperatures, Tclus. We compute
photoionization models that broadly describe the results of the simulations and
compare them with photoionization grids. Results. Our main results are: (a) A
large number of low mass clusters (80% for Mclus = 100 Mo) are unable to form
an H ii region. (b) There are a few overluminous stellar clusters that form H
ii regions. These overluminous clusters preserve statistically the mean value
of obtained by synthesis models, but the mean value cannot be used as a
description of particular clusters. (c) The ionizing continuum of clusters with
Mclus < 10^4 Mo is more accurately described by an individual star with
self-consistent effective temperature(T*) and Q(H0) than by the ensemble of
stars (or a cluster Tclus) produced by synthesis models. (d)Photoionization
grids of stellar clusters can not be used to derive the global properties of
low mass clusters. Conclusions. Although variations in the upper mass limit,
mup, of the IMF would reproduce the effects of IMF sampling, we find that an ad
hoc law that relates mup to Mclus in the modelling of stellar clusters is
useless, since: (a) it does not cover the whole range of possible cases, and
(b) the modelling of stellar clusters with an IMF is motivated by the need to
derive the global properties of the cluster: however, in clusters affected by
sampling effects we have no access to global information of the cluster but
only particular information about a few individual stars.Comment: A&A in pres
Influence of dietary supplementation with an amino acid mixture on inflammatory markers, immune status and serum proteome in lps-challenged weaned piglets
In order to investigate the effect of a dietary amino acid mixture supplementation in lipopolysaccharide (LPS)-challenged weaned piglets, twenty-seven 28-day-old (8.2 ± 1.0 kg) newly weaned piglets were randomly allocated to one of three experimental treatments for five weeks. Diet 1: a CTRL treatment. Diet 2: an LPS treatment, where piglets were intraperitoneally administered LPS (25 µg/kg) on day 7. Diet 3: an LPS+MIX treatment, where piglets were intraperitoneally administered LPS on day 7 and fed a diet supplemented with a mixture of 0.3% of arginine, branched-chain amino acids (leucine, valine, and isoleucine), and cystine (MIX). Blood samples were drawn on day 10 and day 35, and serum was analysed for selected chemical parameters and proteomics. The LPS and LPS+MIX groups exhibited an increase in haptoglobin concentrations on day 10. The LPS group showed an increased cortisol concentration, while this concentration was reduced in the LPS+MIX group compared to the control group. Similarly, the LPS+MIX group showed a decreased haptoglobin concentration on day 35 compared to the two other groups. Immunoglobulin concentrations were affected by treatments. Indeed, on day 10, the concentrations of IgG and IgM were decreased by the LPS challenge, as illustrated by the lower concentrations of these two immunoglobulins in the LPS group compared to the control group. In addition, the supplementation with the amino acid mixture in the LPS+MIX further decreased IgG and increased IgM concentrations compared to the LPS group. Although a proteomics approach did not reveal important alterations in the protein profile in response to treatments, LPS-challenged piglets had an increase in proteins linked to the immune response, when compared to piglets supplemented with the amino acid mixture. Overall, data indicate that LPS-challenged piglets supplemented with this amino acid mixture are more protected against the detrimental effects of LPS.This study was supported by Ajinomoto Animal Nutrition Europe, by Indukern Portugal, Lda., and by Fundação para a Ciência e a Tecnologia (FCT, Lisbon, Portugal) through projects UIDB/CVT/00276/2020 to CIISA and PEST/UID/AGR/4129/2020 to LEAF. It was also supported by national funds, through FCT Stimulus of Scientific Employment Program to author P.A.L. (DL57/2016/CP1438/CT0007) and a Ph.D. grant (SFRH/BD/143992/2019) to author D.M.R.
This work had the support from the Portuguese Mass Spectrometry Net-work, integrated in the National Roadmap of Research Infrastructures of Strategic Relevance (ROTEIRO/0028/2013; LISBOA-01-0145-FEDER-022125)
Avaliação da percepção de cooperação desportiva: Propriedades psicométricas da adaptação portuguesa do CCD
O principal objectivo do presente artigo é apresentar uma sugestão de versão portuguesa do Questionário de Cooperação Desportiva (Garcia-Mas et al., 2006). Este instrumento avalia o grau de cooperação numa situação desportiva, baseada na interacção interpessoal e na busca dos objectivos por parte dos jogadores relativamente aos objectivos da equipa, do treinador e dos seus companheiros. As qualidades psicométricas do instrumento foram avaliadas numa amostra de 127 atletas praticantes de futebol. A análise factorial confirmatória original revelou que os dados obtidos com a versão portuguesa não apresentam uma total sobreposição aos obtidos com a versão espanhola. Assim, adoptando uma estratégia exploratória e tendo em conta a dupla fonte de cooperação (disposicional e situacional), propôs-se uma forma de melhorar a validade de constructo do questionário através de uma nova estrutura factorial e da eliminação de alguns itens. A versão final do QCD-p é composta por 12 itens distribuídos por dois factores disposicionais (Cooperação Condicionada e Cooperação Incondicionada) e um factor situacional (Cooperação com o Treinador)
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