Equilibrium problems in weakly admissible external fields created by pointwise charges

The main subject of this paper is equilibrium problems on an unbounded conductor $\Sigma$ of the complex plane in the presence of a weakly admissible external field. An admissible external field $Q$ on $\Sigma$ satisfies, along with other mild conditions, the following growth property at infinity: $$\lim_{|x| \rightarrow \infty}(Q(x) - \log |x|) = +\infty.$$ This condition guarantees the existence and uniqueness of the equilibrium measure in the presence of $Q$, and the compactness of its support. In the last 10-15 years, several papers have dealt with weakly admissible external fields, in the sense that $Q$ satisfies a weaker condition at infinity, namely, $$\exists M\in(-\infty,\infty],\quad\liminf_{|x| \rightarrow \infty}(Q(x) - \log |x|) = M.$$ Under this last assumption, there still exists a unique equilibrium measure in the external field $Q$, but the support need not be a compact subset of $\Sigma$ anymore. In most examples considered in the literature the support is indeed unbounded. Our main goal in this paper is to illustrate this topic by means of a simple class of external fields on the real axis created by a pair of attractive and repellent charges in the complex plane, and to study the dynamics of the associated equilibrium measures as the strength of the charges evolves. As one of our findings, we exhibit configurations where the support of the equilibrium measure in a weakly admissible external field is a compact subset of the real axis. To achieve our goal, we extend some results from potential theory, known for admissible external fields, to the weakly admissible case. These new results may be of independent interest. Finally, the so--called signed equilibrium measure is an important tool in our analysis. Its relationship with the (positive) equilibrium measure is also explored.Comment: To appear in Journal of Approximation Theor

ARQUITECTURA PARA EL MANEJO DE CONGESTIÓN EN UNA RED DE DATOS CORPORATIVA CON PARTICIPACIÓN DEL USUARIO, BASADO EN INTELIGENCIA COMPUTACIONAL

En este artículo se hace la presentación de un modelo de detección de congestión el cual se implementó en la red LAN de Universidad Nacional sede Bogotá. La idea de este modelo es que con ayuda de los usuarios se haga una detección de los problemas de congestión en la red, de modo que se hace también el diseño de un sistema multiagente que es la base para el modelo de detección. En el proceso se han definido cinco variables de interés las cuales definen el comportamiento de la red LAN y son presentadas en los resultados obtenidos del proceso de detección

Corrigendum: COVID-19 Confinement and Health Risk Behaviors in Spain

In the original article, the reference for Chen et al. (2009) was incorrectly written as “Chen, P., Mao, L., Nassis, G. P., Harmer, P., Ainsworth, B. E., and Li, F. (2009). Wuhan coronavirus (2019-nCoV): the need to maintain regular physical activity while taking precautions. J. Sport Health Sci. 9, 103–104. doi: 10.1016/j.jshs.2020.02.001”. It should be “Chen, P., Mao, L., Nassis, G. P., Harmer, P., Ainsworth, B. E., and Li, F. (2020). Coronavirus disease (COVID-19): The need to maintain regular physical activity while taking precautions. J. Sport Health Sci. 9, 103–104. doi: 10.1016/j.jshs.2020.02.001”. The authors apologize for this error and state that this does not change the scientific conclusions of the article in any way. The original article has been updated

Association Between Physical Activity and Odds of Chronic Conditions Among Workers in Spain

Introduction: Prevention of chronic conditions is a major public health challenge, and achieving minimum recommended levels of physical activity aids in reaching this objective. The aim of our study was to investigate whether levels of physical activity were associated with the prevalence of common chronic conditions among the Spanish workforce. Methods: We retrieved data from the Spanish National Health Survey 2017 (N = 9,695) in which the mean age of participants was 44.4 (standard deviation, 10.4 y), and 47.4% were women. Workers self-reported a set of 6 chronic conditions (ie, chronic low-back pain, chronic neck pain, diabetes, hypertension, depression, and anxiety), and we used the International Physical Activity Questionnaire short form to estimate physical activity. We performed multivariable logistic regression adjusted for possible confounders to assess associations between physical activity and chronic conditions. Results: The final adjusted model showed that performing less than 600 metabolic equivalent-minutes per week of physical activity was associated with significantly increased odds for chronic conditions (adjusted odds ratio [aOR] = 1.18; 95% CI, 1.07–1.30). Of the sex and age subgroups analyzed, this association was significant in men aged 17 to 44 (aOR = 1.21; 95% CI, 1.00–1.46). Among chronic conditions, low-back pain and anxiety were associated with low levels of physical activity, whereas covariates such as body mass index, smoking habits, education level, and occupational class had an important influence on the association between physical activity and chronic conditions. Conclusion: Results suggest that achieving sufficient physical activity could reduce chronic conditions among Spanish workers

La representatividad de las medidas de una media estacional frente a una media anual, en la relación entre la irradiación solar e insolación

Ponencia presentada en: I Congreso de la Asociación Española de Climatología “La climatología española en los albores del siglo XXI”, celebrado en Barcelona del 1 al 3 de diciembre de 1999.[ES]La sencilla relación lineal propuesta por Angstrom-Prescott en 1924 entre la irradiación solar global relativa H/Ho, y la insolación relativa n/N, ha sido sometida, con el transcurso de los años, a numerosos procedimientos experimentales, casi todos ellos tratando un período de varios años. En el Laboratorio de Enseñanza de Física del Medio Ambiente de la Universidad de Valencia, se ha estudiado esta relación utilizando datos correspondientes a días salteados de tres meses, prácticamente coincidentes con el período estacional de otoño. Sin embargo, los resultados finales coinciden en gran medida con los correspondientes a trabajos hechos sobre un período de varios años, lo cual puede significar que, en determinadas ocasiones, las medidas hechas sobre un período estacional, pueden ser representativas de las correspondientes a una media anual o de varios años.[EN]The simple linear relationship proposed by Angstrom-Prescott in 1924 between relative global solar irradiance, H/Ho, and relative insolation, n/N, has undergone, along the years, a number of experimental applications, almost always dealing with periods of several years. In the teaching Environmental Physics Laboratory of the University of Valencia we have studied this relationship using data corresponding to days within a period of three months, practically coinciding with the autumn season. In spite of that, the final results obtained largely coincide with those from other studies carried out over periods of several years. This means that in some occasions, the measurements carried out over a seasonal penod may also be representative of those corresponding to annual means over a number of years

Immediate Impact of the COVID-19 Confinement on Physical Activity Levels in Spanish Adults

Enacted measures to control the spread of COVID-19 disease such as compulsory confinement may influence health behaviors. The present study investigated changes in physical activity (PA) levels during the first days of confinement. Using an online survey, the Spanish population (n = 2042, 54% women, age 35.9 (SD 13.6) years) replied to questions concerning sociodemographic characteristics as well as PA behavior before and during the first week of enacted isolation. Physical activity vital sign (PAVS) short form was used to estimate weekly minutes of PA before and during the isolation period. Statistical analysis used the following tests: Mc Nemar Chi-squared tests, independent and paired samples t-test, and effect size (Cohen’s d). During the first week of confinement, participants reduced their weekly PA levels by 20% (~45.2 weekly minutes (95% CI: 37.4−53.0)). This led to a decrease from 60.6% to 48.9% (difference: 11.7%) (p < 0.0001) in the number of participants meeting the recommended World Health Organization (WHO) PA levels. Subgroups including men, participants aged 43 or over, and those not holding a university degree had the greatest reductions in both weekly minutes of PA and adherence to guidelines. The PA levels of the Spanish population generally declined during the first days of COVID-19 confinement

Resource allocation model for a computer system

This article describes a simulation for resource allocation. As a particular case, it describes how would be the assignment in an ad hoc network. We present the results of a simulation allocating resources from one system (communications network) to another system (agent collections). In the description of the model first shows the behavior of the allocation of resources towards the nodes depending on the usefulness of the network and the satisfaction of the agents. Based on the mathematical model of the tragedy of the commons, the behavior of the system is shown. The usefulness and satisfaction of the system are measured. Resource allocation is modeled as an interaction. The computational model Interaction Nets is used as the basis of the simulation

SHALOS: Statistical Herschel-ATLAS lensed objects selection

Context. The statistical analysis of large sample of strong lensing events can be a powerful tool to extract astrophysical or cosmological valuable information. Their selection using submillimetre galaxies has been demonstrated to be very effective with more than ∼200 proposed candidates in the case of Herschel-ATLAS data and several tens in the case of the South Pole Telescope. However, the number of confirmed events is still relatively low, i.e. a few tens, mostly because of the lengthy observational validation process on individual events. Aims. In this work we propose a new methodology with a statistical selection approach to increase by a factor of ∼5 the number of such events within the Herschel-ATLAS data set. Although the methodology can be applied to address several selection problems, it has particular benefits in the case of the identification of strongly lensed galaxies: objectivity, minimal initial constrains in the main parameter space, and preservation of statistical properties. Methods. The proposed methodology is based on the Bhattacharyya distance as a measure of the similarity between probability distributions of properties of two different cross-matched galaxies. The particular implementation for the aim of this work is called SHALOS and it combines the information of four different properties of the pair of galaxies: angular separation, luminosity percentile, redshift, and the ratio of the optical to the submillimetre flux densities. Results. The SHALOS method provides a ranked list of strongly lensed galaxies. The number of candidates within ∼340 deg2 of the Herschel-ATLAS surveyed area for the final associated probability, Ptot > 0.7, is 447 and they have an estimated mean amplification factor of 3.12 for a halo with a typical cluster mass. Additional statistical properties of the SHALOS candidates, as the correlation function or the source number counts, are in agreement with previous results indicating the statistical lensing nature of the selected sampleJGN acknowledges financial from the Spanish MINECO for a “Ramon y Cajal” fellowship (RYC2013-13256). DH, FA, and LT acknowledge financial support from the I+D 2015 project AYA2015-64508-P (MINECO, FEDER)

Web-GIS approach to preventive conservation of heritage buildings

The effective implementation of preventive conservation approaches demands the employment of standardized and robust tools able to integrate the data coming from multiple sources, inspection and diagnosis techniques, as well as to ensure the proper information transfer between expert and non-expert users. Aiming to make a step forward in the state of the art of current conservation approaches, a cutting edge Web-GIS technology resorting to the intuitiveness of 360° panoramas and 3D point clouds in combination with the Internet of Things is presented in this work, demonstrating how physical and digital worlds can be linked for proper documentation and management of cultural heritage. To validate such a pioneering approach, one of the most representative and complex heritage buildings of Spain is used as a case study: the General Historical Library of Salamanca.This work was financed by ERDF funds through the V Sudoe Interreg program within the framework of the HeritageCare project (Ref. SOE1/P5/P0258), by project Patrimonio 5.0 (SA075P17), by FEDER funds through the Competitive Factors Operational Program (COMPETE) and by the Foundation for Science and Technology (FCT) within the scope of projects POCI-01-0145-FEDER-007633. The authors would like to express their gratitude to the personnel from the General Historical Library of the University of Salamanca as well as to the Centre for Computer Graphics of the University of Minho for the web implementation of the platform

Growth-promoting effects of sustained swimming in fingerlings of glithead sea bream (Sparus aurata L.)

Fish growth is strongly influenced by environmental and nutritional factors and changing culture conditions can help optimize it. The importance of early-life experience on the muscle phenotype later in life is well known. Here, we study the effects of 5 weeks of moderate and sustained swimming activity (5 BL s−1) in gilthead sea bream during early development. We analysed growth and body indexes, plasma IGF-I and GH levels, feed conversion, composition [proximate and isotopic (15N/13C)] and metabolic key enzymes (COX, CS, LDH, HOAD, HK, ALAT, ASAT) of white muscle. Moderate and continuous exercise in fingerlings of gilthead sea bream increased plasma IGF-I, whereas it reduced plasma GH. Under these conditions, growth rate improved without any modification to feed intake through an increase in muscle mass and a reduction in mesenteric fat deposits. There were no changes in the content and turnover of muscle proteins and lipid reserves. Glycogen stores were maintained, but glycogen turnover was higher in white muscle of exercised fish. A lower LDH/CS ratio demonstrated an improvement in the aerobic capacity of white muscle, while a reduction in the COX/CS ratio possibly indicated a functional adaptation of mitochondria to adjust to the tissue-specific energy demand and metabolic fuel availability in exercised fish. We discuss the synergistic effects of dietary nutrients and sustained exercise on the different mitochondrial responses