The Thermodynamics of Cosmic String densities in U(1) Scalar Field Theory

We present a full characterization of the phase transition in U(1) scalar field theory and of the associated vortex string thermodynamics in 3D. We show that phase transitions in the string densities exist and measure their critical exponents, both for the long string and the short loops. Evidence for a natural separation between these two string populations is presented. In particular our results strongly indicate that an infinite string population will only exist above the critical temperature. Canonical initial conditions for cosmic string evolution are show to correspond to the infinite temperature limit of the theory.Comment: 4 pages, 4 figures, RevTe

Multi-Criteria versus Data Envelopment Analysis for Assessing the Performance of Biogas Plants

This paper compares multi-criteria decision aiding (MCDA) and data envelopment analysis (DEA) approaches for assessing renewable energy plants, in order to determine their performance in terms of economic, environmental, and social criteria and indicators. The case is for a dataset of 41 agricultural biogas plants in Austria using anaerobic digestion. The results indicate that MCDA constitutes an insightful approach, to be used alternatively or in a complementary way to DEA, namely in situations requiring a meaningful expression of managerial preferences regarding the relative importance of evaluation aspects to be considered in performance assessment.Multi-criteria decision analysis; DEA; Renewable energy; Biogas

Goal Content for the practice of physical activity and the impact on subjective well-being in older adults

The main goal of this study consisted in an analysis of the impact that the goal content that leads to the practice of physical activity in the elderly population can play on the variables that constitute subjective well-being, as well as to analyze the differences in these variables’ levels according to the amount of physical activity practiced. A total of 300 individuals participated in this study (n=300), including 238 females and 62 males, aged between 60 and 90 years old (M = 68.59; DP = 6.54), who practice differing levels of physical activity. The results enable us to conclude that the goal content for the practice of physical activity has positive effects on the perception of satisfaction with life and on affect. To the same extent, they verify that health is the motivation that has the greatest weight on the practice of physical activity. We also concluded that elderly people who practice more physical activity perceive higher levels of satisfaction with life and positive affect, and lower levels of negative affectinfo:eu-repo/semantics/publishedVersio

Reasons for dropout in swimmers, differences between gender and age and intentions to return to competition

BACKGROUND: This study’s main purpose was to analyze reasons for dropout in competitive swimmers and differences between gender and age groups. The influence of dropout on swimmers intentions to return to competition, invariance across gender and validation of Questionnaire of Reasons for Attrition were also analyzed. METHODS: Study 1 – 366 athletes participated (N.=366; mean age 15.96, SD 5.99) and the data gathered was used for the exploratory analysis, and data gathered on 1008 athletes were used for the confirmatory analysis and the structural equations (N.=1008; mean age 16.26, SD 6.12); Study 2: 1008 athletes participated (N.=1008; mean age 16.26, SD 6.12) on the descriptive and inferential analysis of the reasons behind the practice dropout. The Questionnaire of Reasons Attrition was used in both studies to assess the reasons associated with the practice dropout. RESULTS: In study 1, the results showed an acceptable fit of the measurement model and invariance across gender and also predictive validity regarding swimmers intentions to return to competition (e.g., demands/pressure” negatively predict intentions). In study 2, the main results showed that the most significant reason for dropout in both genders and all age groups was “dissatisfaction/other priorities”; the study also showed there to be differences between gender and age groups (e.g., female and younger athletes valued “demands/ pressure “more). CONCLUSIONS: This study offers useful guidelines for the training process and to support decisions on sports politics to be implemented to overcome the dropout rate. However, it is important to broaden the evidence to other sports and implement programs on identified priority areas based on longitudinal perspectives.info:eu-repo/semantics/publishedVersio

High skilled emigration and wealth distribution

Emigration is a social movement associated to the demand of better life conditions in different countries from those where one was born. In the specific case of skilled workers, this phenomenon is typically characterised in a negative way, due to the country's loss of highly skilled resources, in whose education significant investment was done. While the impact of immigration on labour markets is widely studied and developed, the same is not true in what respects the impact of emigration at emigrant's home countries. This article aims to analyse the effects of high skilled emigration from developed countries on wealth distribution at origin countries. For such purpose, an agent model was developed, and simulations are proposed to depict this phenomenon and discuss the inherent impacts