Diffusive transport in networks built of containers and tubes

We developed analytical and numerical methods to study a transport of non-interacting particles in large networks consisting of M d-dimensional containers C_1,...,C_M with radii R_i linked together by tubes of length l_{ij} and radii a_{ij} where i,j=1,2,...,M. Tubes may join directly with each other forming junctions. It is possible that some links are absent. Instead of solving the diffusion equation for the full problem we formulated an approach that is computationally more efficient. We derived a set of rate equations that govern the time dependence of the number of particles in each container N_1(t),N_2(t),...,N_M(t). In such a way the complicated transport problem is reduced to a set of M first order integro-differential equations in time, which can be solved efficiently by the algorithm presented here. The workings of the method have been demonstrated on a couple of examples: networks involving three, four and seven containers, and one network with a three-point junction. Already simple networks with relatively few containers exhibit interesting transport behavior. For example, we showed that it is possible to adjust the geometry of the networks so that the particle concentration varies in time in a wave-like manner. Such behavior deviates from simple exponential growth and decay occurring in the two container system.Comment: 21 pages, 18 figures, REVTEX4; new figure added, reduced emphasis on graph theory, additional discussion added (computational cost, one dimensional tubes

Time walkers and spatial dynamics of ageing information

The distribution of information is essential for living system's ability to coordinate and adapt. Random walkers are often used to model this distribution process and, in doing so, one effectively assumes that information maintains its relevance over time. But the value of information in social and biological systems often decay and must continuously be updated. To capture the spatial dynamics of ageing information, we introduce time walkers. A time walker moves like a random walker, but interacts with traces left by other walkers, some representing older information, some newer. The traces forms a navigable information landscape. We quantify the dynamical properties of time walkers moving on a two-dimensional lattice and the quality of the information landscape generated by their movements. We visualise the self-similar landscape as a river network, and show that searching in this landscape is superior to random searching and scales as the length of loop-erased random walks

Impact of the covid-19 pandemic on teacher quality of life: A longitudinal study from before and during the health crisis

Background: Prior to the COVID-19 pandemic, teachers were already reporting a low quality of life (QoL) perception, with a significant impact on mental and physical health due to various stress factors associated with work overload. The objective of this study was to evaluate the QoL impact on Chilean teachers before and during the COVID-19 pandemic. The analysis was performed following a longitudinal design on a sample of 63 Chilean teachers in pre-pandemic and COVID-19 pandemic timeframes. QoL perception, along with teachers’ sociodemographic data, was evaluated via the Short-Form 36 Health Survey (SF-36) questionnaire. Sociodemographic variables presented no significant variations in pre-pandemic and pandemic comparisons. QoL, however, showed a significant decrease during the pandemic compared to the pre-pandemic measurement (p < 0.01). In each gender, there were significant differences between pre-pandemic and pandemic timeframes, with a greater impact among women in the mental and physical component summary variables and seven of the eight QoL scales (p < 0.01). Between age categories, people under 45 presented significant differences (p < 0.05) between pre-pandemic and pandemic timeframes in all summary dimensions and measurements. In conclusion, Chilean teachers’ QoL perception has been affected by the COVID-19 pandemic. These findings could be related to work overload due to teleworking or feelings of uncertainty, loneliness, and fear that the pandemic and its associated confinements will worsen

Preinvex functions and weak efficient solutions for some vectorial optimization problem in Banach spaces

AbstractIn this work, we introduce the notion of preinvex function for functions between Banach spaces. By using these functions, we obtain necessary and sufficient conditions of optimality for vectorial problems with restrictions of inequalities. Moreover, we will show that this class of problems has the property that each local optimal solution is in fact global

Anthropometric Characteristics, Body Composition and Somatotype of Elite Pan-American Race Walking 20K

The anthropometric and somatotype evaluation is an essential tool in the selection and control of high-performance athletes. The aim of this study was to describe the somatotype and body composition of male elite race walkers (20 k modality), and its relationship with athletic performance. Twenty-four race walkers participated in this study. The sample was divided into two groups: the race walkers with the best performance (upper 25 percentile; n=7) and the second group (n=17) that corresponds to the rest of the participants. Weight (kg), height (cm), seven skinfolds, two diameters and five perimeters were measured. Body fat percentage (BF%) were estimated with the Yuhasz formula, and the somatotype was used applying the Heath-Carter method. The best performing athletes were taller (178.3 +/- 4.4 cm vs. 173.7 +/- 5.6 cm, p<0.05) and showed a greater ectomorphic component (p<0.05) than the rest of the participants. The somatotype of the best performance athletes was 2.2-2.8-4.1 against the 2.5-3.8-2.9 of the lowest performing athletes. The average time (hours, minute, seconds) of execution of the race in athletes of better performances was 1: 22:40, in comparison with the athletes of lower performances with 1: 32: 41 (p<0.02). The ectomorphic component and height are morphological characteristics that can determine athletic performance of race walkers. It is suggested to consider these factors in the selection of the race walkers. La evaluación antropométrica y del somatotipo es una importante herramienta en la selección y control de los atletas de alto rendimiento. El objetivo de este estudio fue describir el somatotipo y composición corporal de hombres marchistas olímpicos, modalidad 20 k, y su relación con el rendimiento atlético. Veinticuatro atletas de marcha participaron en este estudio. La muestra fue dividida en dos grupos: los marchistas de mejores rendimientos p25 superior (n=7) y el segundo grupo (n=17) que corresponde al resto de los participantes. Se registró el peso (kg), talla (cm), siete pliegues cutáneos, dos diámetros y cinco perímetros. Se estimó el porcentaje de grasa corporal (%GC) con la fórmula de Yuhasz y se describió el somatotipo utilizando el método de Heath-Carter. Se reporta una mayor altura en los atletas de mejor rendimiento (178,3±4,4 cm vs. 173,7±5,6 cm; p<0,05) y mayor componente ectomorfico (p<0,05) que el resto de los participantes. El somatotipo de los atletas de mejor rendimiento fue de 2.2-2.8-4.1 frente al 2.5-3.8-2.9 de los atletas de menor rendimiento. El tiempo promedio (hora, minuto, segundo) de ejecución de la carrera en atletas de mejores rendimientos fue de 1:22:40, en comparación con los atletas de menores rendimientos con 1:32:41 (p <0,02). El componente ectomórfico y altura serian características morfológicas que pueden determinar el rendimiento deportivo de atletas de marcha. Se sugiere considerar estos factores en la selección de los marchistas olímpicos

Uso de la bicicleta como propuesta para mejorar los hábitos de vida saludable

The purpose of the present investigation was to determine to what extent the use of the bicycle influences the improvement of healthy life habits in Secondary Education students of the National College of UNHEVAL Application of the National Hermilio Valdizán University. A research of applied type of quasi-experimental design was developed, the study sample was constituted by 71 students of the sixth cycle of secondary education. The results show that with the use of the bicycle (x), the habits of healthy life were of positive influence. The results show improvement in relation to the practice of healthy lifestyle habits with the good use and handling of the bicycle (x). This situation is demonstrated by the hypothesis test that was favorable when rejecting the null hypothesis, with the value of Z = 8.74 is greater with respect to Z critical Zc = 1.64, which led to state that the use of the Bicycle positively influences the improvement of healthy living habits in students.El propósito de la presente investigación fue determinar en qué medida la utilización de la bicicleta influye en la mejora de los hábitos de vida saludable en los estudiantes de Educación Secundaria del Colegio Nacional de Aplicación UNHEVAL de la Universidad Nacional Hermilio Valdizán. Se desarrolló una investigación de tipo aplicada de diseño cuasi experimental, la muestra de estudio estaba constituido por 71 estudiantes del VI ciclo de educación secundaria. Los resultados evidencian que con la utilización de la bicicleta (x), los hábitos de vida saludable fueron de influencia positiva. Los resultados demuestran mejora en relación a la práctica de los hábitos de vida saludable con la buena utilización y manejo de la bicicleta (x). Esta situación se demuestra con la contrastación de hipótesis que fue favorable al rechazar la hipótesis nula, con el valor de Z =8,74 es mayor respecto a Z crítica Zc = 1,64, en lo que condujo a manifestar que la utilización de la bicicleta influye positivamente en la mejora de los hábitos de vida saludable en los estudiantes

The use of telepsychiatry within forensic practice: a literature review on the use of videolink: a ten-year follow-up

In the last decade, telepsychiatry – the use of telecommunications technologies to deliver psychiatric services from a distance – has been increasingly utilised in many areas of mental health care. Since the review by Khalifa and colleagues in 2007 the body of literature relevant to the forensic applications of telepsychiatry has grown substantially, albeit not by much in the United Kingdom. In the current review, we aim to provide an update summary of the literature published since 2007 to determine the effectiveness and feasibility of increasing telepsychiatry utilisation in forensic practice. The literature reviewed provides some encouraging evidence that telepsychiatry is a reliable, effective and highly acceptable method for delivering mental health care in forensic settings. There are also a number of papers that indicate the use of telepsychiatry may be cost effective for health providers in the longer term. Further research is required to consider the potential legal and ethical implications of using telepsychiatry in forensic settings

Field redefinitions in effective theories at higher orders

The invariance of physical observables under redefinitions of the quantum fields is a well-known and important property of quantum field theory. We study perturbative field redefinitions in effective theories, paying special attention to higher-order effects and their impact on matching to an ultraviolet theory at the classical and quantum levels.Our work has been supported by the Spanish MINECO project FPA2016-78220-C3-1-P (Fondos FEDER) and the Junta de Andalucía grant FQM101. The work of J.C.C. has also been supported by the Spanish MECD grant FPU14