Complejidad computacional y álgebra de funciones

Usually, computational complexity classes are given explicitly using computation models and certain restrictions on available resources (time and/or space). However, in many cases, it is possible to obtain alternative descriptions of these classes as algebras of functions. In this work, some results of this type are presented. Logarithmic and lineal time hierarchies are characterized by functions algebras. We also present some functions algebras for polynomial time, logarithmic space and linear space complexity classes.Las clases de complejidad computacional suelen darse de manera explícita mediante modelos de computación y ciertas restricciones sobre los recursos disponibles (normalmente tiempo y/o espacio). Sin embargo, en muchos casos, es posible obtener descripciones alternativas de dichas clases como álgebras de funciones. En este trabajo se presentan algunos resultados de este tipo, caracterizando mediante álgebras de funciones las jerarquías de tiempo logarítmico y tiempo lineal, y las clases de complejidad de tiempo polinomial, espacio logarítmico y espacio lineal.Universidad de Sevilla. Grado en Matemática

Determinación de la dieta estacional del coyote (Canis latrans) en la región norte de la Reserva de la Biosfera Mapimí, México

ResumenEn este estudio se determinó y comparó la dieta del coyote en sitios dentro y fuera de la Reserva de la Biosfera Mapimí. Se colectó un total de 201 excrementos de coyote, 62 en la temporada seca y 139 en lluvia, de marzo de 2000 a marzo de 2001. Se identificaron 50 y 45 componentes alimenticios en cada temporada, respectivamente. Las muestras se analizaron de manera temporal, para toda el área y por sitios. De los 299 componentes-presas identificados en la temporada seca y 894 en la de lluvia, la mayor frecuencia de consumo se presentó con los artrópodos, principalmente Acrididae, Cicadellidae, Coleoptera y Lepidoptera; mamíferos, sobresaliendo Lepus californicus y Sylvilagus audubonii. El material vegetal, los reptiles y las aves se presentaron con una frecuencia menor. El grupo de los mamíferos aportó la mayor biomasa, con 86.47% en la temporada seca y 72.52% en lluvia. Se observó un mayor consumo de materia vegetal en los sitios con menor grado de modificación. Estos resultados confirman que el coyote es un depredador generalista, omnívoro y oportunista; con una fuerte tendencia a consumir artrópodos durante ambas temporadas, aunque la mayor aportación de biomasa la obtenga de los mamíferos.AbstractIn this study we determined and compared coyote diet within and out of the Mapimí Biosphere Reserve. We collected 201 coyote scats, 62 in the dry season and 139 in the rainy season from March 2000 to March 2001. Samples were analyzed for the general area and by sites. We identified 50 and 45 items for the dry and rainy season, respectively. Out of 299 items identified for the dry season and 894 for the rainy season, the more frequent items were arthropods, mainly Acrididae, Cicadellidae, Coleoptera and Lepidoptera; mammals, mainly Lepus californicus and Sylvilagus audubonii. Plant material, reptiles and birds were less frequently consumed items. Mammals provided the greatest biomass, 86.5% in the dry season and 72.5% in the rainy season. Plant material was consumed more frequently at less modified sites. These results support the idea that coyote is a generalist, omnivore and opportunist predator, with a strong tendency to consume arthropods during the whole year, although the greatest biomass is obtained from mammals

Eficacia de la doble antiagregación para prevenir recurrencias en pacientes con ictus minor o accidente isquémico transitorio de alto riesgo entre 24 y 72 horas de evolución

Actualmente, la doble antiagregación con ácido acetilsalicílico y clopidogrel durante 21 días se utiliza como medida de prevención secundaria en pacientes con ictus menor o accidente isquémico de alto riesgo que no reciben tratamiento de repermeabilización agudo. Dado que los estudios que sustentan esta indicación excluyen a pacientes con más de 24 horas de evolución desde el inicio de los síntomas – muy frecuentes, sin embargo, en la práctica clínica – hemos decidido realizar el proyecto de investigación de un ensayo clínico multicéntrico, aleatorizado, doble ciego y comparado con placebo analizando la eficacia como medida de prevención secundaria del tratamiento doble antiagregante en pacientes con ictus isquémico menor o accidente isquémico transitorio de alto riesgo, entre 24 y 72 horas de evolución, frente a la antiagregación simple. Nuestros resultados tienen como objetivo aumentar el conocimiento y la bibliografía disponible sobre este tema en un subgrupo de pacientes frecuente pero no incluido en el resto de los trabajos.Currently, dual antiplatelet therapy with acetylsalicylic acid and clopidogrel for 21 days is used as a secondary prevention measure in patients with minor stroke or high-risk ischaemic stroke who are not receiving acute repermeabilisation therapy. Since the studies supporting this indication exclude patients with more than 24 hours of evolution since the onset of symptoms - very frequent, however, in clinical practice - we have decided to carry out the research project of a multicentre, randomised, double-blind, placebo-controlled clinical trial. We have analysed the efficacy as a secondary prevention measure of dual antiplatelet therapy in patients with minor ischaemic stroke or high-risk transient ischaemic attack, between 24 and 72 hours of evolution, compared to single antiplatelet therapy. Our results aim to expand the knowledge and literature available on this topic in a subgroup of patients frequently observed but not included in the rest of the papers

CAMBIOS EN LA COMPOSICION DE LAS COMUNIDADES DE ROEDORES EN RELACION A LOS TIPOS DE VEGETACIÓN Y GEOMORFOLOGÍA EN EL PINACATE, SONORA, MEXICO

A study was carried out to characterize various ecological aspects of small mammals in the Sierra del Pinacate, Sonora, México, during the spring of 1981. A survey of rodents was undertaken in nine different plant association of the Gran Desierto of Sonora, and as a result, sixteen species belonging to nine genera were recorded. The rodent fauna consisted of three species of Sciuridae, one species of Geomyidae, seven species of Heteromyidae, and five species of Cricetidae. The Perognathinae was the richest group, with five species. Rodent distríbution was correlated with plant associations and soil substrate. From the total number of species, 16 (94%) dwelled on firm soils, which is the most common substrate. The rock squirrel (SpermophHus variegatus) and the white-throated wood rat (Neotoma albigula] characterized rocky areas, while the desert kangaroo rat (Dipodomys deserti) was restricted to sand dunes, and caracterized the most sandy areas. Habitats were classified according to the presence of rodent species. Perognathus longimembris at\á Neotoma albigula sepárate within our classification the most diverse habitats from the less diverse. The analysís indicates that riparian vegetation was the most important habitat to most of the rodent species.Durante la primavera de 1981, se realizaron muestreos de roedores en las nueve comunidades vegetales principales del Gran Desierto de Sonora. Se registraron 16 especies de roedores: tres de sciúridos, una de geómido, siete de heterómidos y cinco de múridos. La subfamilia Perognathinae fue el grupo más diverso, con cinco especies. Se determinó su distribución respecto a las asociaciones vegetales y al sustrato. Se encontró que los suelos firmes fueron los más utilizados por los roedores. En ellos se localizó al 93.75% de las especies; el ardillón [SpermophHus variegatus) y la rata nopalera {Neotoma albigula) caracterizaron a los sustratos rocosos. Solamente la rata canguro (Dipodomys deserti) fue exclusiva de las dunas más arenosas. Esta última especie separó claramente dentro de la clasificación que se hizo de los sitios con base en las especies de roedores, a los sitios arenosos inestables de los arenosos consolidados. El ratón de bolsas {Perognathus longimembris) y las ratas {Neotoma albigula y N. lepida) separaron dentro de la clasificación a los habitats más diversos de los menos diversos. La vegetación riparia fue importante en cuanto a la diversidad y abundancia de los roedore

Rice Bran-Based Bioplastics: Effects of Biopolymer Fractions on Their Mechanical, Functional and Microstructural Properties

Rice bran is an underutilized by-product of rice production, containing proteins, lipids and carbohydrates (mainly starches). Proteins and starches have been previously used to produce rice bran-based bioplastics, providing a high-added-value by-product, while contributing to the development of biobased, biodegradable bioplastics. However, rice bran contains oil (18–22%), which can have a detrimental effect on bioplastic properties. Its extraction could be convenient, since rice bran oil is becoming increasingly attractive due to its variety of applications in the food, pharmacy and cosmetic industries. In this way, the aim of this work was to analyze the effect of the different components of rice bran on the final properties of the bioplastics. Rice bran refining was carried out by extracting the oil and fiber fractions, and the effects of these two procedures on the final properties were addressed with mechanical, functional and microstructural measures. Results revealed that defatted rice bran produced bioplastics with higher viscoelastic moduli and better tensile behavior while decreasing the water uptake capacity and the soluble matter loss of the samples. However, no significant improvements were observed for systems produced from fiber-free rice bran. The microstructures observed in the SEM micrographs matched the obtained results, supporting the conclusions drawn

Influence of the plasticizer on rice bran-based eco-friendly bioplastics obtained by injection moulding

The manufacture of eco-friendly bioplastic materials from renewable resources to replace petroleum-based plastics has attracted increasing attention. For many years, proteins, lipids and polysaccharides have been proposed as natural biopolymers sources to obtain biodegradable plastic materials. As by-product from the rice industry, rice bran, is an available and non-expensive resource of both proteins and starches, food groups that, properly processed, can be employed in the development of bioplastics. Plasticizers are essential for the manufacture of bioplastics and, when carbohydrate/protein mixtures are used, an adequate selection of plasticizers must be addressed. By these means, a material suitable for thermo-mechanical processing methods is obtained if starches are subjected to shear forces under high temperatures and water excess (gelatinisation). Moreover, additional polyol-based plasticizers, such as glycerol and sorbitol, allow obtaining reinforced products with improved elasticity when protein-based bioplastics are processed. The aim of the present study was to analyse the plasticizing effect of water combined with different proportions of glycerol or sorbitol, as well as their influence on the final bioplastic properties. Results indicate that higher water ratios produce stiffer bioplastics with improved viscoelastic moduli, maximum stress and Young´s modulus, while increasing the glycerol and sorbitol content leads to higher elasticities and water uptake capacities in general. Moreover, sorbitol seems to provide more suitable bioplastics with better tensile (up to 500% in Young´s modulus) and functional properties compared to glycerol.Ministerio de Ciencia e Innovación y FEDER RTI2018-097100-B-C2

Integration of multimedia contents in the teaching of electronics : A practical test case in the teaching of digital circuits at the University of Seville

In this paper we present the integration of multimedia contents in the teaching of Digital Electronic Circuits and Computer Structure, of the first course of Computer Engineering at the University of Seville. Different tools for screenshot and video recording have been used for the preparation of audiovisual material, integrated in the learning platform currently used at the University of Seville. Feedback on the prepared material was collected in a survey, showing the interest and utility found by students in the preparation of theoretical and experimental classes with the videos. Successful results have been obtained in the evaluation of students. Suggestions of improvement and further work to be carried out are also described in the paper

Measuring Performance of Virtual Keyboards Based on Cyclic Scanning

This paper presents an exhaustive study into the different topologies of virtual ambiguous keyboards that operate by scanning techniques, analyzing the text entry average time (tc) and the average number of user inputs (UIc) per character. An mathematical model shows that in comparison with unambiguous one, text entry, in multi-tap mode, doesn’t offers better performance,because both tc and UIc are greater in them. Another method of text entry, called Tnk (Text in n keys), offers improvement with respect to unambiguous keyboards. But solely highly ambiguous keyboard (4-keys keyboards) shows a jointly reduction in tc and UIc . Results obtained with the model do to focus on highly ambiguous keyboard. This paper demonstrate, using simulation with extensive text, that character prediction with TnK mode only have better performance than unambiguous keyboard with character prediction in UIc parameter. Another techniques of text entry are also studied.Junta de Andalucía p08-TIC-363

Analysing the natural population growth of a large marine mammal after a depletive harvest

An understanding of the underlying processes and comprehensive history of population growth after a harvest-driven depletion is necessary when assessing the long-term effectiveness of management and conservation strategies. The South American sea lion (SASL), Otaria flavescens, is the most conspicuous marine mammal along the South American coasts, where it has been heavily exploited. As a consequence of this exploitation, many of its populations were decimated during the early 20th century but currently show a clear recovery. The aim of this study was to assess SASL population recovery by applying a Bayesian state-space modelling framework. We were particularly interested in understanding how the population responds at low densities, how human-induced mortality interplays with natural mechanisms, and how density-dependence may regulate population growth. The observed population trajectory of SASL shows a non-linear relationship with density, recovering with a maximum increase rate of 0.055. However, 50 years after hunting cessation, the population still represents only 40% of its pre-exploitation abundance. Considering that the SASL population in this region represents approximately 72% of the species abundance within the Atlantic Ocean, the present analysis provides insights into the potential mechanisms regulating the dynamics of SASL populations across the global distributional range of the species.Fil: Romero, Maria Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; ArgentinaFil: Grandi, Maria Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Koen Alonso, Mariano. Fisheries And Ocean Canada. Northwest Atlantic Fisheries Centre; CanadáFil: Svendsen, Guillermo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; ArgentinaFil: Ocampo Reinaldo, Matías. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; ArgentinaFil: Garcia, Nestor Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; ArgentinaFil: Dans, Silvana Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia; ArgentinaFil: González, Raul Alberto Candido. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Instituto de Biología Marina y Pesquera Almirante Storni; ArgentinaFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia; Argentin

Historical reconstruction of the population dynamics of southern right whales in the southwestern Atlantic Ocean

Understanding the recovery of whale populations is critical for developing population-management and conservation strategies. The southern right whale (SRW) Eubalena australis was one of the baleen whale species that has experienced centuries of exploitation. We assess here for the first time the population dynamics of the SRW from the southwestern Atlantic Ocean at the regional level to measure numerically the effect of whaling and estimate the population trend and recovery level after depletion. We reconstructed the catch history of whaling for the period 1670–1973 by an extensive review of different literature sources and developed a Bayesian state-space model to estimate the demographic parameters. The population trajectory indicated that the pre-exploitation abundance was close to 58,000 individuals (median = 58,212; 95% CI = 33,329–100,920). The abundance dropped to its lowest abundance levels in the 1830s when fewer than 2,000 individuals remained. The current median population abundance was estimated at 4,742 whales (95% CI = 3,853–6,013), suggesting that the SRW population remains small relative to its pre-exploitation abundance (median depletion P2021 8.7%). We estimated that close to 36% of the SRW population visits the waters of the Península Valdés, the main breeding ground, every year. Our results provide insights into the severity of the whaling operation in the southwestern Atlantic along with the population´s response at low densities, thus contributing to understand the observed differences in population trends over the distributional range of the species worldwide.Fil: Romero, Maria Alejandra. Universidad Nacional del Comahue. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Provincia de Río Negro. Ministerio de Agricultura, Ganadería y Pesca. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Centro Nacional Patagónico. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni"; Argentina. Universidad Nacional del Comahue. Escuela de Ciencias Marinas; ArgentinaFil: Coscarella, Mariano Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentina. Universidad Nacional de la Patagonia "San Juan Bosco"; ArgentinaFil: Adams, G. A.. University of Washington; Estados UnidosFil: Pedraza, Juan C.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: González, Raul Alberto Candido. Universidad Nacional del Comahue. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". - Provincia de Río Negro. Ministerio de Agricultura, Ganadería y Pesca. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni". Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet Centro Nacional Patagónico. Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos "Almirante Storni"; Argentina. Universidad Nacional del Comahue. Escuela de Ciencias Marinas; ArgentinaFil: Crespo, Enrique Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico. Centro para el Estudio de Sistemas Marinos; Argentin