1,261 research outputs found

    Stochastic pump of interacting particles

    Full text link
    We consider the overdamped motion of Brownian particles, interacting via particle exclusion, in an external potential that varies with time and space. We show that periodic potentials that maintain specific position-dependent phase relations generate time-averaged directed current of particles. We obtain analytic results for a lattice version of the model using a recently developed perturbative approach. Many interesting features like particle-hole symmetry, current reversal with changing density, and system-size dependence of current are obtained. We propose possible experiments to test our predictions.Comment: 4 pages, 2 figure

    Swine production simulation model: LIFE SIM

    Get PDF
    Supported by the CGIAR Systemwide Livestock ProgrammeNon-ruminant animals are essential in many resource-poor production systems, particularly in Asia. The feeding strategies are as varied as the different agro ecosystems, thus increasing the challenge faced by researchers and extension agents in the search for appropriate solutions to feeding limitations. Systems analysis provides a unique opportunity to translate existing knowledge into process-based models that can be used to assess year-round feeding strategies at the farm level. Although livestock models have been developed to address similar situations for ruminant animals, swine are seldom included. The present work describes a swine model that analyzes the bioeconomic response to feeding strategies in different production systems. This swine model has been incorporated into the software Livestock Feeding Strategies Simulation Model (LIFE-SIM) complementing the existing models for ruminant species: Dairy, Beef, Goat, and Buffalo (León-Velarde et al., 2006) The model simulates a confined group of animals (at least two females or males) with a weight ranging from 15 to 120 kg, under either an ad libitum or controlled feeding regime with a feed value characterized in terms of dry matter (%), metabolizable energy (ME/kg), crude fiber (%), lysine (%), methionine + cystine (%), threonine (%), and tryptophan (%). The model can store a number of different rations and their prices allowing a comparison during a defined fattening period. Weight gain and the bioeconomic performance of each ration can then be estimated and analyzed

    Health evaluation of a pronghorn antelope population in Oregon

    Get PDF
    During 1996 and 1997, the U.S. Fish and Wildlife Service conducted a study to determine the cause(s) of population decline and low survival of pronghorn antelope (Antilocapra americana) fawns on Hart Mountain National Antelope Refuge (HMNAR) located in southeastern Oregon (USA). As part of that study, blood, fecal, and tissue samples from 104 neonatal fawns, 40 adult does, and nine adult male pronghorns were collected to conduct a health evaluation of the population. Physiological parameters related to nutrition and/or disease were studied. No abnormalities were found in the complete blood cell counts of adults (n = 40) or fawns (n = 44 to 67). Serum total protein and blood urea nitrogen (BUN) levels were lower compared to other pronghorn populations. Does had mean BUN values significantly lower (P < 0.001) in December 1996 than March 1997. Serum copper (Cu) levels in does (range 0.39 to 0.74 ppm) were considered marginal when compared to domestic animals and other wild ungulates. Fawns had low (0.28 ppm) Cu levels at birth and reached the does' marginal values in about 3 days. Whole blood, serum and liver selenium (Se) levels were considered marginal to low in most segments of the pronghorn population. However, serum levels of vitamin E (range 1.98 to 3.27 μg/ml), as determined from the does captured in March, were apparently sufficient to offset any signs of Se deficiency. No clinical signs of Cu or Se deficiency were observed. Fifty-five of 87 dead fawns were necropsied. Trauma, due to predation by coyotes (Canis latrans), accounted for 62% of the mortality during mid-May to mid-July of each year. Other causes included predation by golden eagles (Aquila chrysaetos) (4%), dystocia (2%), septicemic pasteurellosis (4%), starvation (5%), and unknown (23%). Adult females were tested for serum neutralizing antibodies to Brucella spp. (n = 20, negative), Leptospira interrogans (n = 20, negative), bluetongue virus (n = 20, 35% positive), epizootic hemorrhagic disease virus (n = 20, 30% positive), respiratory syncytial virus (n = 18, negative), parainfluenza virus type 3 (n = 18, 67% positive), infectious bovine rhinotracheitis (n = 18, negative), and bovine viral diarrhea (n = 18, negative). Considering the parameters examined, we found no apparent predisposing factors to mortality including those killed by coyotes, but some nutritional parameters suggest that pronghorns on HMNAR exist on a diet low in protein and Se and marginal in Cu. The effect these factors have on the population is not known

    First report of the genus Physaloptera (Nematoda: Physalopteridae) in Lithobates montezumae (Anura: Ranidae) from Mexico

    Get PDF
    AbstractNematode third stage larvae of the genus Physaloptera (Nematoda: Physalopteridae) were recovered from the stomach of Lithobates montezumae (Anura: Ranidae) collected in the Pedregal de San Angel Ecological Reserve in Mexico D. F. (19º11’6.50” N, 99º11’41.42” W; 2 312 m asl). The morphology of the larvae is briefly described and a list of previously recorded localities and hosts in Mexico is given. This study is the first record of Physaloptera sp. parasitizing L. montezumae, and also represents the first helminthological record for anurans in this locality, as well as a new locality record for the nematode genus

    Gestión eficiente de las economías locales a través de estrategias administrativas/Efficient management of local economies through administrative strategies

    Get PDF
    La gestión de la economía local plantea retos al integrarse al sector productivo como uno de sus ejes de crecimiento, este estudio plantea un análisis de la dinámica de estrategias administrativas aplicadas en las microempresas de la ciudad de Macas y su incidencia en la eficiencia para promover el desarrollo del espacio, convirtiéndose éstas en las dos variables de estudio: la gestión de las economías locales y las estrategias administrativas, la metodología de trabajo a utilizar comienza definiendo una investigación de tipo cuantitativa y cualitativa, no experimental, denostándose su independencia a través del método Chi cuadrado determinándose que menos del 50% de negocios aplica algún tipo de estrategia administrativa con una incidencia directa en la gestión de la economía local que trabaja de manera aislada del sector productivo creándose una herramienta a través de la cual se pueda crear una sinergia para lograr el objetivo común que permita eficiencia en el mercado y la gestión pública. Efficient management of local economies through administrative strategies is a stady of the management of the local economy poses challenges when integrating into the productive sector as one of its growth axes, this study proposes an analysis of the dynamics of administrative strategies applied in the micro enterprises of the city of Macas and its impact on efficiency to promote the development of space, these becoming the two variables of study: the management of local economies and administrative strategies, the work methodology to be used begins defining a quantitative and qualitative research, not experimental, denoting its independence through the method Chi square determining that less than 50% of businesses apply some kind of administrative strategy with a direct impact on the management of the local economy that works in isolation from the productive sector, creating a tool through which synergy can be created to achieve the common goal that allows efi science in the market and public management. Palabras clave: Administración, Economía, desarrollo, negocios, gestión, estrategias. Keywords: Administration, Economy, development, business, management, strategies

    Synthesis and characterization of copper coatings on polyimide membranes (PIR 003)

    Get PDF
    The formation of stable metallic/polymeric joints is a huge challenge in the materials sciences. Adhesion requires interphase that is able to specifically interact with the metallic phase. The primary amino groups exhibit copolymers as highly reactive to metal surfaces. This article will give a better understanding of the mechanisms of chemo-absorption by chemical functionalization of polyimides, as well as in the wet development of metallization of materials based on H2 reduction in polymers. And it will be evidenced by comparisons by measures of polymer/metal characterization.Campus Arequip

    Efecto de la adición de organo-hidrotalcita a un suelo agrícola en el comportamiento de los fungicidas tebuconazol y metalaxil bajo condiciones reales de campo

    Get PDF
    2 páginas.-- 2 tablas.-- 2 referencias.-- Poster presentado en XXIV Reunión de la Sociedad Española de Arcillas Sevilla. Libro de Resúmenes: Noviembre de 2015 en Sevilla.Existen numerosos trabajos que abordan las aplicaciones de arcillas naturales, inalteradas o modificadas, como adsorbentes de pesticidas para la depuración de aguas e incluso para actuar como soportes en formulaciones de liberación lenta del pesticida o como barreras inmovilizantes en suelos (Cornejo et al., 2008). La mayoría de estos estudios se han realizado bajo condiciones controladas en el laboratorio y usando minerales de la arcilla naturales del grupo de las esmectitas. En los últimos años, ha aumentado el interés por explotar las propiedades adsorbentes de los hidróxidos dobles laminares (HDLs), también conocidos como hidrotalcitas (HTs) o arcillas aniónicas, cuyas características estructurales guardan cierta relación con las de las esmectitas (Cornejo et al., 2008). Los LDHs consisten en láminas del tipo brucita de un metal divalente con sustituciones isomórficas que proporcionan a las láminas una carga permanente positiva y que es compensada con aniones intercambiables que se sitúan en el espacio interlaminar. Aunque los resultados obtenidos hasta ahora ponen de manifiesto la elevada capacidad de adsorción de los LDHs para muchos pesticidas y la versatilidad que les confiere la posibilidad de modificarlos mediante la intercalación de aniones orgánicos en el espacio interlaminar (Celis et al., 2014), su utilidad como enmendantes para aumentar la capacidad de adsorción de los suelos bajo condiciones ambientales reales aún no ha sido evaluada.Este trabajo ha sido financiado por el Ministerio de Economía y Competitividad (MINECO) a través de los proyectos AGL2011-23779 y AGL2014-51897-R y por la Junta de Andalucía a través del Grupo de Investigación AGR-264, con parte de fondos FEDER-FSE. R. López-Cabeza agradece al MINECO la concesión de una beca pre-doctoral de FPI asociada al proyecto AGL2011-23779.Peer reviewe

    The Rise of Accounting Administration and Its Impact on the Profitability of Microeconomic Management

    Get PDF
    Some taxes may limit microeconomic growth. A greater growth of SMEs that use RISE as part of their administration, especially grocery stores, has been identified in the commercial sector in the city of Macas, Morona canton, Morona Santiago province, Ecuador. This has led to a lack of knowledge about their profitability because the nature of the tax can lead to reduced use of accounting tools. Therefore, the objective of this research was to analyze the accounting administration of RISE and its impact on the profitability of these businesses, and to propose the design of a tool that could contribute to the development of efficient management of the local microeconomic businesses. A deductive quantitative approach was used and data were collected through a survey and interviews. The Chi square test was used to analyze the results. According to the findings, the limitations faced by businesses that use this tax included the generation of monthly income that does not cover the monthly basic basket. Based on the results, we proposed a strategy for the efficient management of the microeconomy that is made up of four tools: conscious strategic planning, administration without tax barriers, efficient accounting tools, and the sustainable development of the company. Keywords: administration, accounting, microeconomics, RISE, management, taxation. Resumen Algunos impuestos pueden limitar el crecimiento microeconómico, en la ciudad de Macas, cantón Morona, provincia de Morona Santiago, Ecuador se ha identificado un mayor crecimiento de PYMEs del sector comercial, de manera especial tiendas de abastos quienes utilizan el RISE como parte de su administración, lo que ha provocado un deficiente conocimiento real de su rentabilidad debido a la naturaleza misma del impuesto que lleva a un uso deficiente y casi nulo de los las herramientas contables, el trabajo tiene como objetivo analizar la administración contable del RISE y su incidencia en la rentabilidad de estos negocios que permitan el diseño de una herramienta que aporte al desarrollo de la gestión eficiente de la microeconomía local, se analizan datos obtenidos a partir de un estudio de tipo deductivo de enfoque cuantitativo, metodología de tipo analítico, correlacional, de campo que aplica instrumentos la recolección de información como la encuesta y entrevista, determina la dependencia de las variables identificadas a través del Chi cuadrado, e identifica como parte de los resultados las limitaciones a las que los negocios que utilizan este impuesto tienen como es la generación de ingresos mensuales que no llegan a cubrir la canasta básica mensual; plantea como parte de la solución al problema la Estrategia para la gestión eficiente de la Microeconomía que se compone cuatro herramientas: la planificación estratégica consciente, administración sin barreras tributarias, herramientas contables eficientes, el desarrollo sustentable de la empresa. Palabras clave: administración, contabilidad, microeconomía, rise, gestión, tributación
    corecore