Retos de los servicios de comunicación ante la Universidad 2.0

Artículo de la sección Tribuna: investigación y profesión

Health effects of youth labor in Colombian youngsters

Este trabajo tiene por objetivo determinar el impacto del trabajo juvenilen la salud de los menores en Colombia. Para mostrar el efecto del trabajo juvenil en la salud se utiliza la información de la encuesta de calidad de vida de 2008 y se estiman modelos econométricos, logit ordenados. Se obtiene como resultado que el trabajo juvenil cuando se desarrolla sin las medidas adecuadas, se constituye en un problema que afecta el bienestar de los jóvenes colombianos.The objective of this paper is to determine health effects that youth labor has in under ages in Colombia. In order to demonstrate the health effects due to child labor, the following information was used: The 2008 quality of life survey, econometric models and ordered logit models. The results concluded that when the labor is carried out without following the necessary requirements, it constitutes a problem that affects the wellbeing of Colombian youngsters.Este trabalho tem por objetivo determinar o impacto do trabalho juvenilna saúde dos menores na Colômbia. Para mostrar o efeito do trabalhojuvenil na saúde se utiliza a informação da enquete de qualidade de vida de 2008 e se estimam modelos econométricos, logit ordenados. Obtém- -se como resultado que o trabalho juvenil quando se desenvolve sem as medidas adequadas, constitui-se num problema que afeta o bem-estar dos jovens colombianos

Los caballos del vino de Caravaca de la Cruz

En número dedicado a: Murci

The dynamics of a triopoly Cournot game when the competitors operate under capacity constraints

Oligopoly theory, i.e., the economic theory for competition among the few, goes back to 1838 and Augustin Cournot [7]. See also [11]. Quite early it was suspected to lead to complex dynamic behaviour and chaos. See Rand 1978 [13]. The probably simplest case under which this happens with reasonable economics assumptions was suggested by one of the present authors in 1991, see [9]. It assumes an isoelastic demand function, which always arises when the consumers maximize utility functions of the Cobb-Douglas type, combined with constant marginal costs. The particular layout was a duopoly, the case of only two competitors. The model was shown to produce a period doubling sequence of ip bifurcations ending in chaos for the outputs of each of the two competitors. Later the triopoly case under these assumptions was studied. See [2], [3], and [4] for examples. An interesting fact is that with three competitors the main frame becomes the Neimark-Hopf bifurcation, which provides new and di erent scenarios. The main reason for economists to study increasing numbers of competitors is to nd out whether it is the number of competitors that uniquely decides a road from monopoly over duopoly, oligopoly, and polypoly, to perfect competition, a state where each rm is so small that its actions cannot in uence the market at all. To nd out about this it is of primary interest to know whether the number of competitors stabilizes or destabilizes the equilibrium state. Some authors have questioned the assumption, to which most economists adhered, that increasing numbers of competitors bring stabilization. However, we must be clear about what we compare. If we study increasing numbers of competitors with constant unit production costs, we are not reducing the size of the rms when their number increases. Constant marginal cost means that potentially each rm has in nite capacity, and adding such rms is not what we want for comparison. It is therefore interesting to combine an increased number of rms with decreasing size of each rm, but in order to do so we have to introduce capacity limits. Already Edgeworth [8] insisted on the importance of capacity limits. It is not so easy to nd non-constant marginal cost functions which allow us to solve for the reaction functions for the rms in explicit form, but one of the present authors, see [12], found one type of function, which models the capacity limit by letting marginal cost go to in nity at a nite output. That paper discussed the competition between two duopolists. The objective of the present paper is to nd out the facts when there are three competitors, and we still keep the assumption of capacity limit

An information-theoretic approach to study spatial dependencies in small datasets

From epidemiology to economics, there is a fundamental need of statistically principled approaches to unveil spatial patterns and identify their underpinning mechanisms. Grounded in network and information theory, we establish a non-parametric scheme to study spatial associations from limited measurements of a spatial process. Through the lens of network theory, we relate spatial patterning in the dataset to the topology of a network on which the process unfolds. From the available observations of the spatial process and a candidate network topology, we compute a mutual information statistic that measures the extent to which the measurement at a node is explained by observations at neighbouring nodes. For a class of networks and linear autoregressive processes, we establish closed-form expressions for the mutual information statistic in terms of network topological features. We demonstrate the feasibility of the approach on synthetic datasets comprising 25–100 measurements, generated by linear or nonlinear autoregressive processes. Upon validation on synthetic processes, we examine datasets of human migration under climate change in Bangladesh and motor vehicle deaths in the United States of America. For both these real datasets, our approach is successful in identifying meaningful spatial patterns, begetting statistically-principled insight into the mechanisms of important socioeconomic problems.This study is part of the collaborative activities carried out under the programs of the Region of Murcia (Spain): ‘Groups of Excellence of the Region of Murcia, the Fundación Séneca, Science and Technology Agency project 19884/GERM/15 and ‘Call for Fellowships for Guest Researcher Stays at Universities andOPIS’ project 21144/IV/19. M.P. would like to express his gratitude to the Technical University of Cartagena for hosting him during a Sabbatical leave and to acknowledge support from the National Science Foundation under grant no.CMMI 1561134. M.R.M. would like to acknowledge support from Ministerio de Ciencia, Innovación y Universidades under grant number PID2019-107800GB-I00/AEI/10.13039/50110001103

Inference of time-varying networks through transfer entropy, the case of a Boolean network model

Inferring network topologies from the time series of individual units is of paramount importance in the study of biological and social networks. Despite considerable progress, our success in network inference is largely limited to static networks and autonomous node dynamics, which are often inadequate to describe complex systems. Here, we explore the possibility of reconstructing time-varying weighted topologies through the information-theoretic notion of transfer entropy. We focus on a Boolean network model in which the weight of the links and the spontaneous activity periodically vary in time. For slowly-varying dynamics, we establish closed-form expressions for the stationary periodic distribution and transfer entropy between each pair of nodes. Our results indicate that the instantaneous weight of each link is mapped into a corresponding transfer entropy value, thereby affording the possibility of pinpointing the dominant weights at each time. However, comparing transfer entropy readings at different times may provide erroneous estimates of the strength of the links in time, due to a counterintuitive modulation of the information flow by the non-autonomous dynamics. In fact, this time variation should be used to scale transfer entropy values toward the correct inference of the time evolution of the network weights. This study constitutes a necessary step toward a mathematically-principled use of transfer entropy to reconstruct time-varying networks.This work was supported by the National Science Foundation under Grant Nos. CMMI 1433670, CMMI 1561134, and CBET 1547864, the US Army Research Office under Grant No. W911NF-15-1-0267 with Dr. Samuel C. Stanton and Dr. Alfredo Garcia as the program managers, and Ministerio de Economía y Competitividad de Espana and FEDER funds under Grant No. ECO2015-65637-P. This study is part of the collaborative activities carried out under the program Groups of Excellence of the Region of Murcia, the Fundacion Seneca, Science and Technology Agency of the Region of Murcia Project No. 19884/GERM/15

A Non-Parametric Approach to Spatial Causality

The purpose of this paper is to show the capacity of a new non-parametric test based on symbolic entropy and symbolic dynamics to deal with the detection of linear and non-linear spatial causality. The good performance of the new test in detecting spatial causality and causal weighting matrix is notable and gives rise to an expectation that it may form a adequate tool for constructive specification searches.Causality; Spatial Dependence; Spatial Weight Matrices

A non-parametric independence test using permutation entropy

In the present paper we construct a new, simple and powerful test for independence by using symbolic dynamics and permutation entropy as a measure of serial dependence. We also give the asymptotic distribution of an affine transformation of the permutation entropy under the null hypothesis of independence. An application to several daily financial time series illustrates our approach