Anthropogenic Modifications to Estuaries Facilitate the Invasion of Non-Native Species

ew observations of non-indigenous species (NIS) in coastal waters, such as the Gulf of Cadiz (Spain) have increased since 1980 and more or less exponentially in the last five years. Ballast water has become the most significant pathway for unintentional introductions of NIS into marine ecosystems. For example, the marine larvae of crustacean decapods that inhabit the water column could be transported in ballast water. Although elevated concentrations of metals are toxic to many marine organisms, some of them have evolved effective detoxification, or avoidance mechanisms making it possible to consider they have a superior ability to withstand exposures to these toxicants. In this text, we try to reinforce the hypothesis that anthropogenic modifications (such as chemical alterations and modified environments) benefit NIS with broad environmental tolerances. Taking these risks into account, a reinforcement of efficient Ballast Water Management Systems to respond to today's challenging environmental conditions is discussed.This essay was developed in the framework of the InvBlue project (PID2019105978RA-I00) from the Spanish "Ministerio de Economia y Competitividad (MINECO), Plan Nacional I + D", and within the 2014-2020 ERDF Operational Programme and Department of Economy, Knowledge, Business and University of the Regional Government of Andalusia (Spain). Project Ref.: FEDER-UCA18 -108023. We thank Jon Nesbit for the English revision. We are also grateful to two anonymous referees for their critiques and suggestions that improved the manuscript

Analysis of a non-uniformly elliptic and nonlinear coupled parabolic–elliptic system arising in steel hardening

The goal of this work is to analyse the existence of weak solutions to a coupled nonlinear parabolic–elliptic system derived from the heating industrial process of a steel workpiece, and whose unknowns are the electric potential, the magnetic vector potential and the temperature. We introduce the harmonic regime because of the different time scales related to the electric potential and the magnetic vector potential versus the temperature. This lead us to a new system of nonlinear partial differential equations.Ministerio de Economía y Competitividad MTM2010–16401Junta de Andalucía FQM–31

Partial Differential Equations: On the existence of solutions for a strongly degenerate system

We establish the existence of a solution in a certain sense to a strongly degenerate problem consisting in a coupled nonlinear parabolic-elliptic system. The diffusion term in the parabolic equation is of the form − div a(x, t, u, ∇u), where a is an operator of the Leray–Lions type. Moreover, the second equation is nonuniformly elliptic.Sur l’existence de solutions pour un système fortement dégénéré. On montre l’existence d’une solution dans un certain sens d’un problème fortement dégénéré constitué par un système non-linéaire de deux équations aux dérivées partielles couplées du type parabolique-elliptique, le terme de diffusion de l’équation parabolique étant de la forme − div a(x, t, u, ∇u), où a est un opérateur du type de Leray–Lions. En outre, la seconde équation de ce système est non-uniformement elliptique.Ministerio de Ciencia y Tecnología BFM2003-01187Junta de Andalucía FQM-31

Renormalized Solutions to a Nonlinear Parabolic-Elliptic System

The aim of this paper is to show the existence of renormalized solutions to a parabolicelliptic system with unbounded diffusion coefficients. This system may be regarded as a modified version of the well-known thermistor problem; in this case, the unknowns are the temperature in a conductor and the electrical potential.Ministerio de Ciencia y Tecnología BFM2003-01187Junta de Andalucía FQM-31

The thermistor problem with degenerate thermal conductivity and metallic conduction

The aim of this work is to establish the existence of a capacity solution to the thermistor problem supposing that the thermal and the electrical conductivities are not bounded below by a positive constant value. Furthermore, the thermal conductivity vanishes at points where the temperature is null. These assumptions on data include the case of practical interest of the Wiedemann–Franz law with metallic conduction and lead us to very complex mathematical situations.Ministerio de Ciencia y Tecnología BFM2003-01187Junta de Andalucía FQM-31

On certain doubly non-uniformly and singular non-uniformly elliptic systems

We consider the steady state of the thermistor problem consisting of a coupled set of nonlinear elliptic equations governing the temperature and the electric potential. We study the existence of weak solutions under two kind of assumptions. The first one considers the case in which the two diffusion coefficients are not bounded below far from zero, arising to a doubly non-uniformly elliptic system. In the second one, we assume in addition that the thermal conductivity blows up for a finite value of the temperature, arising to a singular and non-uniformly coupled system.Ministerio de Educación y Cultura PB98-0583junta de Andalucía FQM-31

On an induction–conduction PDEs system in the harmonic regime

We study the existence of weak solutions to a nonlinear coupled parabolic–elliptic system arising in the heating industrial process of a steel workpiece. The unknowns are the electric potential, the magnetic vector potential and the temperature. The different time scales related to the electric potential and the magnetic vector potential versus the temperature lead us to introduce the harmonic regime. This yields to a new system of nonlinear partial differential equations.Ministerio de Economía y Competitividad MTM2010-16401Junta de Andalucía FQM-31

Simetría fractal en la ecuación logística

En la actualidad en el programa de ingeniería física se hace necesario fortalecer el área de los sistemas dinámicos, profundizando en el modelamiento y en el análisis del comportamiento fractal de dichos sistemas. Un trabajo de grado en esta área es un punto de partida de una línea de profundización en Mecánica Clásica y Sistemas Dinámicos y nuestros estudiantes tienen las herramientas para el desarrollo de este trabajo. Por otra parte, debido a que la ecuación logística es tan utilizada para diversos modelos, es de esperar que cada uno de ellos presente una forma específica según sea el objeto de estudio, por ejemplo para la química en el crecimiento de poblaciones de bacterias, para la demografía en el estudio de poblaciones, en economía en el análisis de series de tiempo. Es importante verificar el comportamiento fractal de la ecuación logística mediante el método de Diferencia hacia Adelante y de ser esto cierto entonces los casos específicos también poseen simetría fractal y por lo tanto pueden ser modeladas como un fractal

Scavenging behavior by Phyllonotus oculatus (Gastropoda: Muricidae) in a South Atlantic reef

Scavengers play a key role in nutrient cycling and in the energy transfer between the terrestrial-aquatic interface (Beasley et al. 2012). Obligatory scavengers feed exclusively on carrion, while some predator species act opportunistically as facultative scavengers when carrion is available (Morton 2006; Moleón and Sánchez-Zapata 2015). Species of the gastropod family Muricidae, such as Ergalatax contracta (Reeve, 1846), display the opportunistic habit of scavenging other predators’ leftovers on subtidal sands (Morton 2006). Muricidae is one of the largest families of carnivorous snails, utilizing a specialized shell-drilling ability to assess their prey (Dietl and Herbert 2005)

Desarrollo de una metodología de implementación de los conceptos de TOC (Teoría de restricciones), para empresas colombianas

La Teoría de Restricciones (TOC) es un sistema de pensamiento gerencial que ha sido aplicado con éxito en multitud de empresas en el mundo. Sin embargo, no existe una documentaciónadecuada de su implementación en Pequeñas y Medianas Empresas (PyMEs) en Colombia, por lo que no hay un protocolo de implementación que guíe al empresario en dicho proceso.Al realizar una investigación documental, unida con un diagnóstico y aplicación piloto en dos pequeñas empresas del sector de manufactura de productos plásticos, se estructuróuna propuesta que parte desde conocer el estado actual de la empresa, satisfacer algunos requerimientos previos a la implementación de técnicas de TOC y la implementaciónpropiamente dicha de las mismas. Como conclusión se encontró que antes de emprender cualquier proceso de mejoramiento es necesario "ordenar la casa": Lograr una claridad en los aspectos administrativos, productivos y de calidad básicos, para asígarantizar la efectividad y sostenibilidad de cualquier avance que se alcance.