1,248 research outputs found

    Els pesticides i el medi ambient

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    Chemical plasmatic levels in repeat breeder cows after a.i.

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    Numerous studies report important metabolic imbalances during the transitional period of the cow affecting its reproduction. However, only a few of them concern the early period of gestation, where variations in the plasmatic components related to repeat breeding may take place. In that period there are great hormonal changes, as those happening during the formation of the CL and the subsequent progesterone secretion. With the aim of going into this subject in depth, we carried out a study to determine concentrations of calcium, inorganic phosphorus, glucose, magnesium, copper and zinc in the blood plasma of 42 Holstein Freisian cows, during 32 days after the AI. A photometer BioSystem BTS 310 was used to determine those metabolic parameters. Variance analyses were performed on animals grouped according to their reproductive state (A=pregnant; B=non pregnant) and number of AIs (A1=pregnant in 1-2 AIs; A2=pregnant in ≥3 AIs; B1=repeat breeder, non pregnant in 1-2 AIs; B2=repeat breeder, non pregnant in ≥3 AIs). The concentrations studied did not vary depending on the reproductive state after the AI. This indicates that in the early pregnancy period a suitable homeostasis is kept, regardless of the hormonal variations occurring and the process of maternal recognition of gestation. However, when comparing results obtained from repeating cows and pregnant cows according the number of AIs received significant variations are shown in calcium, phosphorus, glucose, magnesium, and zinc levels, what makes think about their possible role as etiological agents of the repeating cows syndrome.Numerosos trabajos demuestran que durante el periodo de transición de la vaca aparecen desequilibrios metabólicos importantes que repercuten sobre la reproducción. Sin embargo, pocos hacen referencia al periodo temprano de gestación, donde es posible que, entre otras, las alteraciones o modificaciones en algunos constituyentes plasmáticos estén relacionadas con la repetición de celos. En dicho periodo existen grandes cambios hormonales, como los que suceden durante la formación del CL y subsecuente secreción de progesterona. Con el objetivo de ahondar en estos aspectos se llevó a cabo una experiencia en la que se determinaron las concentraciones de calcio, fósforo inorgánico, glucosa, magnesio, cobre y zinc presentes en el plasma sanguíneo de 42 vacas Holstein Freisian durante 32 días posteriores a la IA. Para determinar dichos parámetros metabólicos se empleó un fotómetro BioSystem BTS 310. Se realizaron análisis de varianza entre los animales agrupados según su estado reproductivo y según el número de IAs recibidas. Las concentraciones químicas determinadas en este estudio no sufrieron variaciones dependientes del estado reproductivo tras la IA, lo que indica que durante este periodo temprano se mantiene una homeostasis adecuada independientemente de los procesos de reconocimiento materno de la gestación que están en marcha o de variaciones hormonales que tienen lugar. Sin embargo, al comparar los resultados obtenidos entre las vacas repetidoras y las gestantes según el número de IAs recibidas se observan variaciones significativas en cuanto a los niveles de calcio, fósforo, glucosa, magnesio y zinc, lo que hace pensar en su posible participación en el denominado síndrome de la vaca repetidora

    The internationalisation of the Spanish SME sector

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    As part of a wider research program, we analysed the theoretical framework and the recent developments of the process of internationalisation (transnationalisation) of the small- and medium-sized enterprises in Spain. The paper highlights the main trends and barriers of this internationalisation process. Methodology included document analyses, interviews, and the analyses of statistical databases

    Ovarian follicular dynamics in repeat breeder cow: ultrasonography and progesterone level

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    The aim of this study was to examine follicular development patterns in eighteen repeat breeder cows through spontaneous oestrus cycles. Ovarian ultrasonographic examinations over 32 days after artificial insemination revealed that two follicular waves were the predominant patterns in animals with this syndrome (72.2 percent). Cycles with one or four waves rarely appeared. The ovulatory follicular diameter (day 0) was larger (p<0.01) in cycles with a small number of waves; no differences were detected between ovulatory and anovulatory dominant follicles. Progesterone plasmatic concentrations were determined by RIA and differences were not significant when cycles with two or three waves were compared. The number of follicular waves was higher (2 or 3 waves) with longer interovulatory intervals (22.3 ± 1.89 vs 23.0 ± 2.0; n.s.) and older cows (7.0 ± 2.64 vs 4.38 ± 1.66 years; p<0.05). Mean ovulatory follicular diameter was 1.78 ± 0.36 cm. It can be concluded that cows with the repeat breeder cow syndrome more frequently present two follicular wavesEl objetivo de este trabajo era caracterizar los patrones de desarrollo folicular en 18 vacas repetidoras de celos a lo largo de ciclos sexuales espontáneos. Se llevaron a cabo exámenes ecográficos de los ovarios durante 32 días posteriores a la inseminación, observándose que el patrón de dos ondas era el más frecuente en vacas repetidoras alcanzando un 72,2 p.100, mientras que los de 3 ondas estuvieron presentes en el 16,6 p.100 de los ciclos estudiados. Se registraron ciclos con 1 y 4 ondas, aunque esta condición es muy poco frecuente. El diámetro del folículo ovulatorio fue mayor en ciclos con menos número de ondas (p<0,01); no se detectaron diferencias entre folículos dominantes ovulatorios o anovulatorios. Las concentraciones de progesterona no mostraron diferencias entre los distintos patrones de crecimiento folicular. Se apreció que los ciclos con más ondas foliculares estaban acompañados de intervalos interovulatorios más largos y aparecía en vacas más viejas. El diámetro folicular ovulatorio medio alcanzó 1,78 ± 0,36 cm. Los resultados permiten afirmar que la dinámica folicular más frecuente en vacas repetidoras es la de dos ondas

    Modelling languages quality evaluation by taxonomic analysis: a preliminary proposal

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    El paradigma de la ingeniería dirigida por modelos (MDE por sus siglas en inglés) promueve el uso de modelos conceptuales en procesos de ingeniería e investigación sobre sistemas de información. Como productos de ingeniería los modelos conceptuales deben tener calidad, la cual aplica tanto a los modelos conceptuales como los lenguajes de modelado empleados para construir dichos modelos. Debido a los múltiples retos, divergencias y tendencias para evaluación y aseguramiento de la calidad en contextos MDE, una forma para ejecutar un proceso de evaluación de la calidad es usar una técnica donde la aplicabilidad y metas de los artefactos de modelado puedan ser contrastadas con los principios esenciales del desarrollo de sistemas de información. Este trabajo formula un conjunto de requisitos conceptuales y metodológicos para un marco de evaluación de la calidad de lenguajes de modelado con el potencial de abordar algunos de los retos abiertos de calidad en MDE. Para este propósito, se propone usar principios del popular marco de trabajo Zachman para sistemas de información, como una herramienta taxonómica aplicada sobre artefactos de modelado usados en un desarrollo de un sistema de información, en aras de ejecutar procedimientos analíticos sobre modelos alineados con una arquitectura de referencia para sistemas de información, y con razonamientos ontológicos. En este trabajo se expone cómo el marco Zachman soporta análisis sobre modelos para propósitos de calidad por su administración nativa de la semántica.The Model-Driven Engineering (mde) paradigm promotes the usage of conceptual models in information systems (is) engineering and research. As engineering products, conceptual models must have quality, which applies on both conceptual models and modeling language employed to build them. This paper presents a modeling language quality evaluation framework. This framework uses the principles from the popular Zachman framework for information systems as a taxonomic tool applied over modeling rtifacts used in an information system development. The purpose of this taxonomic tool is to perform analytic procedures that are aligned with an is reference architecture and ontological reasoning. Throughout this work, we describe how the Zachman framework supports analytics over modeling languages for quality purposes by its native management of semantics

    Crecimiento gonadal y reproducción del erizo de mar Sphaerechinus granularis (Lamarck, 1816) (Echinodermata, Echinoidea) en el sureste de España

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    The gonadal index and reproductive state of the sea urchin Sphaerechinus granularis were studied for a year in three populations from southeast Spain. The development of the gonad during the period of study was assessed using histological methods and four maturity stages were considered for female specimens and two for male specimens. The study of gonad development showed a clearly defined annual cycle of gametogenesis with a single spawning period in summer-autumn. It begins in June at Torremuelle and Palmeral and a month later at La Herradura. The three populations exhibited similar reproductive patterns, having mature gonads in almost all the months. Though the environmental conditions were similar, the population from La Herradura had the highest Gonadosomatic Index value (GSI) and that from Torremuelle the lowest one.Se ha estudiado el índice gonadosomático y los estados reproductivos del erizo de mar Sphaerechinus granularis durante un año en tres poblaciones del sureste de España. El desarrollo de la gónada se estudió usando métodos histológicos; además, el estado de los individuos se determinó utilizando cuatro categorías de desarrollo gonadal para las hembras y dos para los machos. Existe un único periodo de puesta a lo largo del año, entre verano y otoño. En las estaciones de Torremuelle y Palmeral la puesta comienza en junio mientras que en La Herradura tiene un retraso de un mes. Las tres poblaciones muestran patrones reproductivos semejantes y se caracterizan por tener gónadas maduras casi todos los meses, aunque en proporciones distintas. Los valores del índice gonadosomático son mayores en La Herradura y menores en Torremuelle a pesar de que las condiciones ambientales son similares

    A review of the role of spatial resolution in energy systems modelling:Lessons learned and applicability to the North Sea region

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    The importance of spatial resolution for energy modelling has increased in the last years. Incorporating more spatial resolution in energy models presents wide benefits, but it is not straightforward, as it might compromise their computational performance. This paper aims to provide a comprehensive review of spatial resolution in energy models, including benefits, challenges and future research avenues. The paper is divided in four parts: first, it reviews and analyses the applications of geographic information systems (GIS) for energy modelling in the literature. GIS analyses are found to be relevant to analyse how meteorology affects renewable production, to assess infrastructure needs, design and routing, and to analyse resource allocation, among others. Second, it analyses a selection of large scale energy modelling tools, in terms of how they can include spatial data, which resolution they have and to what extent this resolution can be modified. Out of the 34 energy models reviewed, 16 permit to include regional coverage, while 13 of them permit to include a tailor-made spatial resolution, showing that current available modelling tools permit regional analysis in large scale frameworks. The third part presents a collection of practices used in the literature to include spatial resolution in energy models, ranging from aggregated methods where the spatial granularity is non-existent to sophisticated clustering methods. Out of the spatial data clustering methods available in the literature, k-means and max-p have been successfully used in energy related applications showing promising results. K-means permits to cluster large amounts of spatial data at a low computational cost, while max-p ensures contiguity and homogeneity in the resulting clusters. The fourth part aims to apply the findings and lessons learned throughout the paper to the North Sea region. This region combines large amounts of planned deployment of variable renewable energy sources with multiple spatial claims and geographical constraints, and therefore it is ideal as a case study. We propose a complete modelling framework for the region in order to fill two knowledge gaps identified in the literature: the lack of offshore integrated system modelling, and the lack of spatial analysis while defining the offshore regions of the modelling framework

    Changes in the growth rate of Chlamydomonas reinhardtii under long-term selection by temperature and salinity: Acclimation vs. evolution

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    We investigated the roles of acclimation and different components involved in evolution (adaptation, chance and history) on the changes in the growth rate of the model freshwater microalga Chlamydomonas reinhardtii P. A. Dang. exposed to selective temperature and salinity. Three C. reinhardtii strains previously grown during one year in freshwater medium and 20 °C were exposed to 5 °C temperature increase and a salinity of 5 g L−1 NaCl. Cultures under each selective scenario and in combination (increase of salinity and temperature), were propagated until growth rate achieved an invariant mean value for 6 months (100–350 generations, varying as a function of scenario and strain). The changes of the growth rate under increased temperature were due to both adaptation and acclimation, as well as history. However, acclimation was the only mechanism detected under salinity increase as well as in the selective scenario of both temperature and salinity, suggesting that genetic variability would not allow survival at salinity higher than that to which experimental populations were exposed. Therefore, it could be hypothesized that under a global change scenario an increase in salinity would be a greater challenge than warming for some freshwater phytoplankton.This work was financially supported by the project CGL2017-87314-P (Ministerio de Economía, Industria y Competitividad, Spain) and the project PID2020-118045-GB-I00 (Ministerio de Ciencia e Innovación, Spain). Funding for open access charge: Universidad de Málaga/CBUA
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