On the connectivity and restricted edge-connectivity of 3-arc graphs

A 3−arc of a graph G is a 4-tuple (y, a, b, x) of vertices such that both (y, a, b) and (a, b, x) are paths of length two in G. Let ←→G denote the symmetric digraph of a graph G. The 3-arc graph X(G) of a given graph G is defined to have vertices the arcs of ←→G. Two vertices (ay), (bx) are adjacent in X(G) if and only if (y, a, b, x) is a 3-arc of G. The purpose of this work is to study the edge-connectivity and restricted edge-connectivity of 3-arc graphs.We prove that the 3-arc graph X(G) of every connected graph G of minimum degree δ(G) ≥ 3 has edge-connectivity λ(X(G)) ≥ (δ(G) − 1)2; and restricted edge- connectivity λ(2)(X(G)) ≥ 2(δ(G) − 1)2 − 2 if κ(G) ≥ 2. We also provide examples showing that all these bounds are sharp.Peer Reviewe

On the λ'-optimality of s-geodetic digraphs

For a strongly connected digraph D the restricted arc-connectivity λ'(D) is defined as the minimum cardinality of an arc-cut over all arc-cuts S satisfying that D − S has a non trivial strong component D1 such that D − V (D1) contains an arc. Let S be a subset of vertices of D. We denote by ω+(S) the set of arcs uv with u ∈ S and v ∈ S, and by ω−(S) the set of arcs uv with u ∈ S and v ∈ S. A digraph D = (V,A) is said to be λ'-optimal if λ'(D) = ξ'(D), where ξ'(D) is the minimum arc-degree of D defined as ξ(D) = min{ξ'(xy) : xy ∈ A}, and ξ'(xy) = min{|ω+({x, y})|, |ω−({x, y})|, |ω+(x)∪ω−(y)|, |ω−(x)∪ω+(y)|}. In this paper a sufficient condition for a s-geodetic strongly connected digraph D to be λ'-optimal is given in terms of its diameter.Further we see that the h-iterated line digraph Lh(D) of a s-geodetic digraph is λ'-optimal for certain iteration h.Peer Reviewe

The voice of birth families to improve visits in foster care

In foster care, contact visits with birth families play an important role in relation to the child’s wellbeing, and they may impact on placement outcomes. However, the views of birth parents with respect to such visits have largely been unexplored. This research is part of a project financed by the regional government of Andalusia (SEJ-7106) regarding contact visits in foster care. This study aims to give voice to parents and gather their views about contact visits, including how they might be improved. Participants were 23 birth families who had contact visits with 35 children in non-kinship foster care. Semi-structured individual interviews were conducted in order to explore two key aspects: the parents’ opinions regarding the contact visits and the main areas they felt needed improving. The interviews were transcribed and the transcripts were examined using an inductive method of open coding to identify themes among participants’ responses. The main themes to emerge concerned their general view of contact visits and the organization of visits. The paper discusses the study’s implications of the findings for practice.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Bayesian design and analysis of replications in scientific experimentation

En la práctica estadística es frecuente la replicación de experiencias estadísticas, justificada por muy diversos intereses: ratificar conclusiones, estudiar la variación en las respuestas cuando se experimenta sobre una población distinta, validar un modelo, detectar sesgos, etc. Al disponer, antes de replicar, de los resultados de cierto estudio previo, es razonable pensar en buscar un buen diseño para la réplica utilizando la información que dicho primer estudio proporciona. Un diseño óptimo de la réplica consistirá en decidir, asumido un modelo, sobre el menor tamaño muestral que otorga al investigador suficientes garantías de concluir con éxito en su inferencia. Una modelización jerárquica bayesiana permite precisar fácilmente las relaciones entre datos y poblaciones (original y replicada) y derivar conclusiones sobre los resultados más probables (en función del tamaño de la réplica) a través de las distribuciones a posteriori y predictivas que se obtengan

The enzymatic determination of glucose in carbonated beverages: a useful tool for the undergraduate students to learn the basis of enzymatic analysis and the comparison of two analytical methods

The importance of enzymatic analysis in biochemistry, clinical chemistry and food chemistry is undoubted. The course "Applied Biochemistry" in our Faculty is aimed to undergraduate students of Chemistry and Biochemistry. In this subject, the principles and applications of enzymatic analysis are presented to the students, who receive a theoretical introductory lecture in the classroom before they carry out an experiment that should be feasible to be solved in a short laboratory period. The experimental protocol here presented, based on the enzymatic determination of glucose in carbonated beverages, has been implemented at the University of Málaga and it has been optimized according to the students’ results and commentaries along the last years. It aims to illustrate basic issues relating enzymatic analysis, including its potential application to food chemistry. Although there are several enzymatic methods that can be used for the determination of glucose, we selected the one based on the coupled reactions of glucose oxidase (GOD; EC 1.1.3.4.) and peroxidase (POD; EC 1.11.1.7.) because the kinetic constants of glucose oxidase allow the mentioned enzymatic reactions to be used in both, the end point and the kinetic enzymatic analysis methods. In this way, data for two different protocols for the determination of glucose concentration are obtained by the students from a single reaction mixture. Students construct a calibration curve for each method using a glucose standard solution, and use them to determine the glucose concentration in the problem solutions. The inclusion of replicate samples in the determination of the glucose concentration of an “ideal problem” (glucose in purified water) is used to illustrate the principles of statistics in the lab, and comparison with the “real value” allows an estimation of the accuracy of each method. The evaluation of glucose concentration in four carbonated beverages: coloured coke and uncoloured tonic sodas (regular or sugarless in both cases) makes student to recognise the appearance of interferences that should be either avoided or eliminated. Since all samples are analysed by means of end-point and kinetic methods, students can discuss the applicability of each method to these specific analytical problems. They are also encouraged to compare both analytical methods in terms of sensitivity, selectivity, accuracy, and time consumed. Chemistry and Biochemistry undergraduate students having performed this experiment in our laboratories have found it formative, interesting and challenging.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A practice project to prevent the cookbook model as modus operandi for biochemistry laboratory learning

Laboratory learning is a crucial component of chemistry and biochemistry instruction and should be conceived as a way to develop students’ reasoning, technical or practical skills, introducing them into the scientific method principles. Nevertheless, the heavily criticized “expository instruction style”, characterized by a cookbook nature, is still the most widespread style of laboratory instruction in our universities. Alternative learning styles based in the inquiry, discovery and problem-based pedagogical approaches, have been reported to promote students’ problem solving skills, critical thought and self-confidence development. We are currently involved in the Educative Innovation Project PIE17-065, funded by University of Malaga, aimed to improve the teaching practice of Biochemistry laboratory to undergraduate students. Based on an enzymatic analysis of glucose in soft-drinks we have developed a laboratory protocol as a part of a full practice project where students must work before and after the lab session, in order to prevent the cookbook model as modus operandi, therefore preventing the situation where the students get a first glimpse of the experiment protocol whereas they put on their lab coat. The learning activities have been designed to move our students from the passive role that characterizes the step-by-step procedures, to an active and critical attitude that starts before and remains after their laboratory session, also minimizing time, space, and equipment resources. Our results have shown that this experiment has improved the learning of both, future biochemists and chemists, which showed a very positive perception of the whole practical project.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. PIE 17-06

Board Independence And Firm Performance: The Moderating Effect Of Institutional Context

This study proposes a new research approach to examine the relationship between board independence and corporate performance, measured by technical efficiency. Moreover, this paper examines the moderating role that institutional factors exert on this relationship through the legal system—the content of law and its enforcement. The research questions are examined using an international sample of 2185 firms from 2006 to 2015, applying truncated regression models for panel data and employing data envelopment analysis to examine efficiency as a measure of performance. This paper supports that board independence increases the firm's technical efficiency. Even more, greater legal and judicial protection exerts a positive moderating effect on the previous relationship by protecting private benefits for insiders, among other aspects. Thus, the positive impact of independent directors on efficiency is greater when firms operate in countries with a greater extent of law and enforcement. Our findings include endogeneity checks using instrumental variables

Resilience to the short- and long-term behavioral effects of intermittent repeated social defeat in adolescent male mice

Background Exposure to intermittent repeated social defeat (IRSD) increases the sensitivity of mice to the rewarding effects of cocaine in the conditioned place preference (CPP) paradigm. Some animals are resilient to this effect of IRSD, though research exploring this inconsistency in adolescent mice is scarce. Thus, our aim was to characterize the behavioral profile of mice exposed to IRSD during early adolescence and to explore a potential association with resilience to the short- and long-term effects of IRSD. Methods Thirty-six male C57BL/6 mice were exposed to IRSD during early adolescence (PND 27, 30, 33 and 36), while another 10 male mice did not undergo stress (controls). Defeated mice and controls then carried out the following battery of behavioral tests; the Elevated Plus Maze, Hole-Board and Social Interaction Test on PND 37, and the Tail Suspension and Splash tests on PND 38. Three weeks later, all the mice were submitted to the CPP paradigm with a low dose of cocaine (1.5 mg/kg). Results IRSD during early adolescence induced depressive-like behavior in the Social Interaction and Splash tests and increased the rewarding effects of cocaine. Mice with low levels of submissive behavior during episodes of defeat were resilient to the short- and long-term effects of IRSD. In addition, resilience to the short-term effects of IRSD on social interaction and grooming behavior predicted resilience to the long-term effects of IRSD on cocaine reward. Conclusion Our findings help to characterize the nature of resilience to the effects of social stress during adolescence

Learning contract, co-operative and flipped learning as useful tools for studying metabolism

Es el Abstract de una comunicación a un congreso internacional sobre educaciónUndergraduate students in Biology identify Metabolic Biochemistry as a particularly difficult subject. This is due to the fact that students need to interconnect properly all the contents of its syllabus throughout their study of the subject in order to get a global insight of the complex regulatory features controlling metabolic pathways within the metabolic network under different physiologic and pathologic conditions, as well as metabolism as a whole. Due to these objective difficulties, a high percentage of our students face the study of this subject as a very hard task beyond their forces and capacities. This perception leads to high rates of premature dropout. In previous years, less than 40% of all the registered students attended the examinations of Metabolic Biochemistry (a subject in the second year of the Degree of Biology at our University). Even worse, less than 25% of our students passed the exams. From the academic year 2015/16 on, we are developing innovative teaching projects (PIE15-163 and PIE17-145, funded by University of Malaga) aimed to increase our student loyalty to the subject (and hence to increase their attendance to exams) and to help them to learn more effectively metabolism and its regulation. These innovative teaching projects are based on the use of several powerful tools: a learning contract and problem-based learning within the framework of group tasks promoting an actual collaborative learning in a flipped classroom. The present communication will show the implementation of the PIE15-163 and PIE17-145 projects and some results obtained from them.This work was supported by Malaga University funds granted to the educational innovation project PIE17-145. The attendance to the END2018 International Conference on Education and New Developments (June 2018, Budapest, Hungary) has received a grant from "I Plan Propio Integral de Docencia. Universidad de Málaga"]

Comparative study between nail retraining with gauze bandaging and the nail remodeling with acrylics as a conservative treatment for stage I and IIa onychocryptosis

Objective: Onychocryptosis is one of the most prevalent onychopathies, being a frequent reason for consultation in podiatric clinical practice. Conservative treatments are the first therapeutic choice, with nail remodeling using clotrimazole gel emerging as an alternative, although its medium-term effectiveness is unknown. The objective of this study was therefore to compare the efficacy of the technique of nail retraining using gauze bandaging with that of nail remodeling for the conservative treatment of stage I and IIA onychocryptosis. Methods: An analytical, randomized clinical trial study was performed following a longitudinal and prospective design. A sample was selected of 20 subjects presenting stage I and IIA onychocryptosis. Of these, 10 cases formed the group of nail retraining using gauze bandaging, and the other 10 the nail remodeling group. The presence of recurrence in a 3-month period was evaluated. Results: Before the intervention, the patients in the retraining group presented pain of 6.7 ± 1.9 vs. 6.8 ± 1.6 in the remodeling group, with no significant difference between the two (p = 0.900). After the 3-month follow-up period, seven of the retraining group patients presented recurrence of onychocryptosis vs. only one in the remodeling group. Conclusion: The technique of nail remodeling has a lower recurrence rate than that of nail retraining with gauze bandaging, with the pain, inflammation, and infection reported being less, and with greater patient satisfactio