On the behaviour of differential evolution for problems with dynamic linear constraints

Evolutionary algorithms have been widely applied for solving dynamic constrained optimization problems (DCOPs) as a common area of research in evolutionary optimization. Current benchmarks proposed for testing these problems in the continuous spaces are either not scalable in problem dimension or the settings for the environmental changes are not flexible. Moreover, they mainly focus on non-linear environmental changes on the objective function. While the dynamism in some real-world problems exists in the constraints and can be emulated with linear constraint changes. The purpose of this paper is to introduce a framework which produces benchmarks in which a dynamic environment is created with simple changes in linear constraints (rotation and translation of constraint's hyperplane). Our proposed framework creates dynamic benchmarks that are flexible in terms of number of changes, dimension of the problem and can be applied to test any objective function. Different constraint handling techniques will then be used to compare with our benchmark. The results reveal that with these changes set, there was an observable effect on the performance of the constraint handling techniques.Maryam Hasani-Shoreh, Marìa-Yaneli Ameca-Alducin, Wilson Blaikie, Frank Neuman

Análisis de crecimiento estacional de una pradera de trébol blanco (Trifolium repens L)

The objective of the present study was to assess a growth analysis of white clover (Trifolium repens L.) and determine the optimal harvest time per season. The experiment was carried out at the Colegio de Postgraduados, Campus Montecillo, Texcoco, Mexico. Twenty-four 3.7 X 1.7 m plots were used, distributed in a completely randomized design, with eight treatments and three replicates per station. The treatments consisted of successive weekly cuts, during a regrowth cycle of 8 wk, in each season of the year. At the beginning of the study, a uniform cut was made and the residual forage was determined. The evaluated variables were: accumulation of dry matter, botanical and morphological composition, and leaf area index of white clover. The highest forage accumulation (P<0.05) occurred in the eighth week in spring (2,688 kg DM ha-1). Leaf production was higher (P<0.05) in spring, autumn and winter. The highest leaf area index was reached in the eighth week in spring (3.0; P<0.05). It is recommend exploiting the white clover meadow in the sixth week of the spring-summer period and in the seventh week of autumn-winter.El objetivo del presente estudio fue evaluar un análisis de crecimiento del trébol blanco (Trifolium repens L) y determinar el momento óptimo de cosecha por estación. El experimento se realizó en el Colegio de Postgraduados, Campus Montecillo, Texcoco, México. Se utilizaron 24 parcelas de 3.7 X 1.7 m, distribuidas en un diseño completamente al azar, con ocho tratamientos y tres repeticiones por estación. Los tratamientos consistieron en cortes semanales sucesivos, durante un ciclo de rebrote de ocho semanas, en cada estación del año. Al inicio del estudio se realizó un corte de uniformización y se determinó el forraje residual. Las variables evaluadas fueron: acumulación de materia seca, composición botánica y morfológica e índice de área foliar del trébol blanco. La mayor acumulación de forraje (P<0.05) se presentó en la octava semana en primavera (2,688 kg MS ha-1). La producción de hoja fue mayor (p < 0.05) en primavera, otoño e invierno. El mayor índice de área foliar se alcanzó en la octava semana en primavera (3.0; P< 0.05). Se recomienda aprovechar la pradera de trébol blanco en la sexta semana para primavera-verano y séptima semana en otoño e invierno

On the performance of baseline evolutionary algorithms on the dynamic knapsack problem

Evolutionary algorithms are bio-inspired algorithms that can easily adapt to changing environments. In this paper, we study single- and multi-objective baseline evolutionary algorithms for the classical knapsack problem where the capacity of the knapsack varies over time. We establish different benchmark scenarios where the capacity changes every τ iterations according to a uniform or normal distribution. Our experimental investigations analyze the behavior of our algorithms in terms of the magnitude of changes determined by parameters of the chosen distribution, the frequency determined by τ and the class of knapsack instance under consideration. Our results show that the multi-objective approaches using a population that caters for dynamic changes have a clear advantage on many benchmarks scenarios when the frequency of changes is not too high.Vahid Roostapour, Aneta Neumann, and Frank Neuman

Estudio de la eficiencia en la compresión de datos en un sistema de escaneo tridimensional mediante el algoritmo RLE

Los estudios realizados actualmente se enfocan en el estudio de lascaracterísticas y efectos del ruido presentes en el canal y las perturbaciones generados en la información transmitida, el presente trabajo se realiza el estudio de la eficiencia del algoritmo de compresión Run Length Encoding (RLE) en un canal de comunicación alámbrico, mediante la medición de algunos parámetros es posible determinar la eficiencia del uso del canal, empleando el algoritmo RLE, para la realización del estudio se utiliza una metodología, que permite determinar la eficiencia del uso del canal, previo al empleo del algoritmo de compresión y posterior a él, de esta forma es posible determinar la eficiencia del uso del canal, en este trabajo se verifica un incremente en el aprovechamiento del uso del canal debido al algoritmo de compresión RLE

S.O.S. Pinna nobilis: A Mass Mortality Event in Western Mediterranean Sea

A mass mortality event (MME) impacting the bivalve Pinna nobilis was detected across a wide geographical area of the Spanish Mediterranean Sea (Western Mediterranean Sea) in early autumn 2016. Underwater visual censuses were conducted across several localities separated by hundreds of kilometers along the Spanish Mediterranean coasts and revealed worrying high mortality rates reaching up to 100% in the center and southernmost coasts of the Iberian Peninsula including Balearic Islands. Populations on the northern coasts of the Spanish Mediterranean Sea seemed to be unaffected (Catalonian region). Histological examination of affected individuals revealed the presence of a haplosporidan-like parasite within the digestive gland being probably the pathogen that causes this mortality. The present MME has spread rapidly, causing high mortality rates in infected populations. Taking into account the degree of impact, the geographic extent, and the high probability that the infection is still in a spreading phase, this might be considered the largest MME ever registered for P. nobilis up to date, forcing this emblematic bivalve into a critical viability status over hundreds of kilometers of coastVersión del edito

Environment and Time as Constraints on the Biogeographical Distribution of Gibbons

We develop a time budget model for the hylobatid family with the aim of assessing the extent to which their contemporary and historical biogeographic distributions might be explained by ecological constraints. The model uses local climate to predict time budgets, and from this the limiting size of social group that animals could manage at a given location. The model predicts maximum group sizes that vary between 3-15 within the taxon’s current distribution, indicating that the combination of their dietary and locomotor styles with the kinds of habitats they inhabit radically constrain group size. Beyond the edges of their current distribution, sustainable group size rapidly tends to zero, although if they had been able to bypass some of these areas, they would have found very suitable habitats in southern India and beyond the Wallace Line. While travel time would be a major constraint on group size at larger group sizes, as it is in great apes, the main factor limiting the gibbon’s current distribution is the time they need to spend resting that is imposed on them by the environment. The model also indicates that gibbons would not now be able to survive in regions of central and southeastern China where they are known to have occurred within historical times, perhaps because historical climate change following the Little Ice Age of the C18th made these regions uninhabitable for them. Finally, our results indicate that gibbons have the ecological capacity to live in larger groups than they do, making it unlikely that their adoption of monogamy reflects purely ecological constraints

Natural population die-offs : lessons for conservation

Population die-offs generally refer to the loss of a large number of individuals in a population over a short time interval. When die-offs are attributable to one or more extreme natural events, they are referred to as “natural” population die-offs (also abbreviated as “NPDOs”). Despite the increased number of studies reporting natural population die-offs we still have only a limited understanding of the processes driving such phenomena. The first section of this thesis, a review chapter, highlights the variety of pathways by which extreme natural events (including extreme climatic events) can drive episodes of high mortality. It also introduces a framework for assessing vulnerability to population declines applied to terrestrial mammals. The vulnerability to these declines can be heightened if species have high susceptibility and/or a poor adaptive capacity. Using a database of 72 natural population die-offs (NPDOs) of terrestrial mammal species we tested a set of hypothesis related to species’ biological traits (body mass, home range, foraging strategy, territoriality) the main aim of chapter two investigate whether these traits are significant predictors of the observed degree of population losses caused by extreme natural events (“NPDO severity”). In parallel with intrinsic biology, the degree of exposure to threat processes determines the fate of species and their constituent populations. In this context, chapter three maps the degree of overlap between the extant geographical distribution of terrestrial mammals and areas of recent past exposure to cyclones and droughts. Species whose distributions have a high overlap with extreme climatic events are expected to be at greater threat than currently recognized by their biology alone. Chapter four then introduces a vulnerability assessment to cyclone-driven population declines based on the interactions between species biology, the species’ extant geographical range and recent past exposure to tropical cyclones. This is with the aim of determining species that are both, intrinsically vulnerable and highly exposed. This objective is addressed for the 19 terrestrial mammals listed as critically endangered by Mexican Law: Among Mexican mammalian fauna they stand already at the first line to disappear due to human-mediated impacts and extreme climate-related phenomena can increase such risk. Therefore there is a critical need to identify those further jeopardized by climatic impacts and implement comprehensive management practices to protect them. Great changes in the environment have the potential to generate large mortality events. However, the processes by which extreme climatic events shape population growth and trajectory are overlooked. In the final chapter of this thesis a population viability analysis is performed for a predator-free, well-monitored and undisturbed primate population harboured in Agaltepec Island, Los Tuxtlas, Mexico. This translocated population share ecological and demographic features within the range of variation reported for the subspecies in Los Tuxtlas region. In light of the expected increment in the frequency of extreme climatic events (e.g., cyclones for Los Tuxtlas region), systems as the one presented here can help to understand demographic consequences that extreme agents of disturbance could trigger on isolated populations embed in hostile landscapes where data is still not available

Síntesis y estudios docking de nuevos sistemas guanidinio del ácido oleanólico como potenciales agentes antiproliferativos

"El presente trabajo se encuentra dividido en 2 capítulos que describen transformaciones del triterpenoide natural ácido oleanólico (OA). En el capítulo I, se describe una ruta sintética de 5 pasos para obtener compuestos con un fragmento guanidinio a partir del OA (16); así mismo, se generaron compuestos con el fragmento tioureido (11-15) empleando reacciones de acoplamiento con isotiocianatos comerciales como intermedios sintéticos clave en la preparación de los derivados de tipo guanidino. Cabe mencionar que los compuestos 17-20 no fueron posibles de sintetizar de manera experimental debido a la contingencia por COVID-19 que suscitó el cierre de labores a partir de marzo 2020. En el capítulo II se describen los perfiles farmacocinéticos y de toxicidad de los compuestos 11-20 usando programas de predicción computacional, adicionalmente, se presenta la relación estructura-actividad de los compuestos 11-20 con estudios docking en la proteína REα, debido a que son responsables de controlar la transcripción de ADN nuclear necesaria para el desarrollo y la reproducción humana (clave PDB: 3ERT) teniendo de referencia al fármaco Tamoxifeno (77)"