4,547 research outputs found
Robust DEA efficiency scores: A probabilistic/combinatorial approach
In this paper we propose robust efficiency scores for the scenario in which
the specification of the inputs/outputs to be included in the DEA model is
modelled with a probability distribution. This proba- bilistic approach allows
us to obtain three different robust efficiency scores: the Conditional Expected
Score, the Unconditional Expected Score and the Expected score under the
assumption of Maximum Entropy principle. The calculation of the three
efficiency scores involves the resolution of an exponential number of linear
problems. The algorithm presented in this paper allows to solve over 200
millions of linear problems in an affordable time when considering up 20
inputs/outputs and 200 DMUs. The approach proposed is illustrated with an
application to the assessment of professional tennis players
Ingesta de alcohol y práctica de actividad físico-deportiva en jóvenes
This study addresses the relationship between two lifestyle factors that have a particular impact on the health of young people, as are the usual practice of leisure-time physical activity and alcohol consumption. Alcohol consumption and leisure-time physical activity was assessed in a sample of 6362 high school students from Compulsory Secondary Education (ESO) and Post-compulsory Secondary Education (ESPO). We used a Pearson Chi-square test to estimate the significant differences between groups. The results show that the patterns of alcohol drinking and leisure-time physical activity of our sample are similar to the rest of the Spanish adolescents. Differences in the consumption of alcohol depending on the quantity and intensity of leisure-time physical activity.El presente estudio aborda la relacion entre dos factores del estilo de vida que tienen una especial incidencia en la salud de los jovenes, como son la practica habitual de ejercicio fisico y el consumo de alcohol. Se evaluaron en 6362 estudiantes de Ensenanza Secundaria Obligatoria (ESO) y Post-obligatoria (ESPO) el consumo de alcohol y la cantidad habitual de actividad fisica. Se realizo un analisis descriptivo e inferencial, con una prueba de estadistico �Ô2 (Chi-cuadrado de Pearson) para estimar las diferencias significativas existentes en los diferentes grupos. Los resultados muestran que los adolescentes estudiados tienen patrones de comportamiento similares al resto de la población española en lo que se refiere a la ingesta habitual de bebidas alcohólicas y práctica de actividad física cotidiana. Existen diferencias en el consumo habitual de alcohol en función de la cantidad e intensidad de actividad físico-deportiva realizada
Landscape Assessment via Regression Analysis
This paper presents a methodology for assessing the visual quality of agricultural landscapes through direct and indirect techniques of landscape valuation. The first technique enables us to rank agricultural landscapes on the basis of a survey of public preferences. The latter weighs the contribution of the elements and attributes contained in the picture to its overall scenic beauty via regression analysis. The photos used in the survey included man-made elements, positive and negative, agricultural fields, mainly of cereals and olive trees, and a natural park. The results show that perceived visual quality increases, in decreasing order of importance, with the degree of wilderness of the landscape, the presence of well-preserved man-made elements, the percentage of plant cover, the amount of water, the presence of mountains and the colour contrast.landscape assessment, visual quality, landscape elements, landscape value, Land Economics/Use, H41, Q21, Q26,
Developing a Business Communication Master's Degree: Fulfilling the Specific Needs of the Industry
Nominalismo, Voluntarismo y contingentismo
En este trabajo se revisan las tesis centrales del pensamiento de Ockham
—representacionismo, voluntarismo, contingentismo— y la critica de L. Polo a las
mismas. Se divide en tres partes: teoria del conocimiento, psicologia y ética, y metafísic
Authentic materials in the Business English classroom: Annual Reports
International firms are interested in getting the best possible professionals, those who are able to communicate accurately at the workplace. To help them, the use of authentic materials in the classroom can enhance students’ options to succeed in their prospective working environment. From a genre-based perspective, annual reports can be useful for that purpose, as they offer a real corporate image of the companies, helping students to understand better how firms work. This paper shows a practical implementation of three activities that are carried out among three different groups of students at a Spanish public university to promote their communicative skills. To do so we have followed a multimodal approach, so that our students can experience, conceptualize and apply meaning to a genre (annual report), completing some tasks in which they have to communicate in English the information appearing in those texts. The final pedagogical recommendations enhance the benefits of using authentic materials in the English for business communication classroom. The combination of multimodality and genre-based pedagogy lead students to understand the current meaning construction in professional settings.
Transcultural study of perceived competence in physical education and leisure time
El objetivo fue analizar la influencia de la competencia percibida en el
sexo, el patrón de actividad físico-deportiva y las etapas de cambio en la práctica
de actividad físico-deportiva de tiempo libre. La muestra fue de 2168 estudiantes
del primer curso de Enseñanza Secundaria Obligatoria, de Costa Rica (423),
México (408) y España (1337). Se realizaron análisis de Chi-cuadrado (x2), tstudent,
ANOVA y modelo lineal univariante. Los alumnos con mayor índice de
práctica y en etapas activas presentaron una mayor competencia percibida,
siendo superior también en los chicos que en las chicas. Por los resultados de
esta investigación, hay pocas posibilidades de que la mayoría de los escolares
lleguen a ser físicamente activos. Por tanto, en los tres países existe un nivel
bajo de actividad físico-deportiva que podría mejorar a través de diseños
metodológicos en la Educación Física escolar orientados a la mejora de
competenciaThe objective was to analyze the influence of perceived competence on gender,
the pattern of physical-sport activity and the stages of change in the practice of
physical activity in leisure. The sample was of 2168 students of the first course
of Compulsory Secondary Education, of Costa Rica (423), Mexico (408) and
Spain (1337). Chi-square (x2), t-student, ANOVA and univariate linear model
analyzes were performed. The students with the highest index of practice and in
active stages presented a greater perceived competence, also being superior in
the boys than in the girls. From the results of this research, it is very probably
that most schoolchildren will not become physically active. Therefore, in the
three countries there is a low level of physical-sport activity that could be
improved through methodological designs in Physical Education aimed at
improving perceived competenc
Arthropod pests and their management, natural enemies and flora visitors associated with castor (Ricinus communis), a biofuel plant: a review.
Interest in bioenergetic crops, such as the castor oil plant Ricinus communis (Euphorbiaceae), for production of biodiesel has increased in recent years. In this paper, phytophagous arthropods, their natural enemies and floral visitors associated with this plant in the world are reviewed. Despite its insecticidal properties, arthropods have been reported feeding on R. communis plants. The arthropod pests of R. communis damage all parts of the plant, including the seeds, where some toxic compounds are even more concentrated. In the scientific databases, we found reports of 193 arthropods associated to R. communis in different parts of the world. This information obtained in the scientific databases was concentrated in a database and analyzed according to the coevolutive hypothesis, which allows us to predict that the greatest wealth and abundance of phytogenic arthropods is found in the center of origin by R. communis. According to this review, Achaea janata, Spodoptera litura, Edwardsiana flavescens, Liriomyza trifolii, L. sativae, Spilosoma obliqua, Cogenethes punctiferalis, Oxyrhachis taranda, and Helicoverpa armigera are the most devastating pests in Asia. In Africa, Agrotis ipsilon, S. exigua, Nezara viridula, Trialeurodes ricini, and Tetranychus urticae were mentioned as the most important. In Central and South-America, Phyllophaga sp., Agrietes sp., Erinnyis ello, N. viridula, Corythucha gossypii, Falconia antioquiana, and S. marima are reported as pests of economic importance. The most commonly reported natural enemies of some of these arthropod pests were species of Bacillus thuringiensis, B. cereus, B. popilliae, Trichogramma achaeae, T. chilonis, T. minutum, T. australicum, T. dendrolimi, T. pretiosum, T. evanescens, Microplitis rufiventris, M. maculipennis, M. ophiusae, Telenomus remus, T. proditor, Stethorus siphonulus and S. histrio. Apis mellifera is recorded as the main insect pollinator of R. communis. Pest management methods used against the arthropod pests of R. communis include biological, ethological, mechanical, cultural, genetic, and chemical control
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