3,871 research outputs found

    Estructura del hábitat y dominios vitales en Podarcis hispanica (Steindachner, 1870)

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    The legacy of translocations among populations of the Ibizan Wall Lizard, Podarcis pityusensis (Squamata: Lacertidae)

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    The Ibizan wall lizard, Podarcis pityusensis, was the subject of several documented 25 translocations by the German herpetologist Martin Eisentraut, in 1930. He aimed to initiate 26 long-term experiments into the evolution of melanism and other morphological traits and 27 accordingly reported introductions into five islets that (he believed) contained no lizards. In 28 this study, we analysed the genetics and morphological characteristics of individuals we found 29 there. We found no lizards on two of the islets, namely Escull de Tramuntana or Galera, but 30 for the first time, detected a large population on a third, Es Vaixell. Analyses of microsatellite 31 DNA placed individuals from a fourth islet, Dau Gran, with those from the islet of Escull 32 Vermell. They are also morphologically close to individuals from Escull Vermell. This 33 suggests that selection pressures could have favoured the Escull Vermell phenotype following 34 introduction. Eisentraut founded the Es Vaixell population with non- melanic Ibizan 35 specimens, but the present day population of Es Vaixell was found to be fully melanic. Genetic 36 markers support a strong similarity between Es Vaixell and Na Gorra, and indicate that, in all 37 likelihood, the individuals introduced by Eisentraut have left no descendants. It is likely that 38 Es Vaixell already contained lizards prior to this introduction. For reasons which we discuss, 39 the translocations have revealed less than Eisentraut would have originally hoped for, although 40 they do provide some potential insights into lizard morphological evolution following 41 colonization

    Los obstáculos para el desarrollo profesional de profesoras de enseñanza secundaria en ciencias experimentales

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    Este trabajo es un estudio de casos de profesoras de ciencias experimentales, con el objetivo de determinar los obstáculos que surgen de la interacción entre la reflexión y la práctica de aula, así como su influencia en el desarrollo profesional. El estudio se efectúa en dos planos diferentes, una investigación de orientación cualitativa y otra de naturaleza crítica, orientado hacia el desarrollo profesional. Los instrumentos de análisis fueron de diversa índole, entre ellos el horizonte de la integración. Los resultados mostraron que las profesoras analizadas se encontraban, a rasgos generales, en proceso de evolucionar de forma más compleja su práctica de aula, mostrando un grado de integración notable con los procesos reflexivos. A un nivel más particular, la naturaleza de los obstáculos es diferente para cada profesora

    La dimensión afectiva olvidada del conocimiento didáctico del contenido de los profesores de ciencias

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    Shulman se refería al paradigma olvidado de la investigación sobre el profesor el que no se hubiese considerado el contenido de la materia específica, lo que le llevó a desarrollar el Conocimiento Didáctico del Contenido (CDC). Sin embargo la dimensión afectiva y emocional podemos considerarla la parte olvidada del CDC. Shulman consideraba que el CDC es una forma de razonamiento y de acción didáctica por medio de la cual los profesores transforman el contenido en representaciones comprensibles a los estudiantes. Investigaciones recientes indican que no hay acción humana, sin una emoción que la haga posible. Desde esta perspectiva es indudable que las emociones del profesor formarían parte del CDC. En el simposio mostraremos la relación entre lo cognitivo y lo afectivo del profesor y la necesidad de incluir la dimensión afectiva en el CDC de los profesores de ciencias

    DE LA TASACIÓN DE LA TIERRA A LA VALORACIÓN AGRARIA Y RURAL

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    In this study, we propose a general systematic view in the first place which stems from the classical theory of land appraisal and evolves in the direction of the productive activity of the agrarian enterprise, and in the second place territorial planning, with the aim of presenting a full scenario of the activity of professionals of the current agrarian and rural scope.En el presente trabajo se propone una sistemática general que parte de la teoría clásica de la valoración de la tierra y que evoluciona en la dirección de la actividad productiva de la empresa agraria en primer lugar, y en segundo la ordenación del territorio, con el fin de presentar un panorama completo de la actividad del profesional de ámbito agrario actual y rura

    ELOGIO DEL AGRÓNOMO

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    In this paper some thoughts about the agronomist profession are presented, from the perspective of the evolution of agriculture as a source of food and employment to a new globalized scenario where the application of new technologies force us to rethink the essence of a profession based primarily on the conservation and enhancement of nature and the rural landscape, and the need to flee from siren calls with proposals in which the means replace the ends.En el presente trabajo se plantean algunas reflexiones sobre la profesión del Agrónomo desde la perspectiva de la evolución de la agricultura como fuente de alimentación y empleo hasta un nuevo escenario globalizado donde la aplicación de las nuevas tecnologías obligan a replantearse la esencia de una profesión basada fundamentalmente en la conservación y mejora de la naturaleza y el paisaje, rural y la necesidad de huir de cantos de sirena con propuestas en las cuales los medios sustituyen al fin

    Virus-mediated transient expression techniques enable gene function studies in black-grass

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    Even though considerable progress has been made in weed ecology, weed molecular biology has been hindered by an inability to genetically manipulate weeds. Genetic manipulation is essential to demonstrate a causative relationship between genotype and phenotype. Herein we demonstrate that virus-mediated transient expression techniques developed for other monocots can be used in black-grass (Alopecurus myosuroides) for loss- and gain-of-function studies. We not only use virus induced gene silencing (VIGS) to create the black-grass exhibiting reduced PHYTOENE DESATURASE expression and virus-mediated overexpression (VOX) to drive GREEN FLUORESCENT PROTEIN, we demonstrate these techniques are applicable to testing hypotheses related to herbicide resistance in black-grass. We use VIGS to demonstrate that AmGSTF1 is necessary for the resistant biotype Peldon to survive fenoxaprop application and show the heterologous expression of the bialaphos resistance gene with VOX is sufficient to confer resistance to an otherwise lethal dose of glufosinate. Black-grass is the most problematic weed for winter-cereal farmers in the UK and Western Europe as it has rapidly evolved adaptions that allow it to effectively avoid current integrated weed management practices. Black-grass also reduces yields and therefore directly threatens food security and productivity. Novel disruptive technologies which mitigate resistance evolution and enable better control over this pernicious weed are therefore required. These virus-mediated protocols offer a step change in our ability to alter genes of interest under controlled laboratory conditions and therefore to gain a molecular-level understanding of how black-grass can survive in the agri-environment

    A comparative study of the electrochemical properties of vitamin B-6 related compounds at physiological pH

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    A comparative study of vitamin B6 group and related compounds in buffered solutions using electrochemical techniques has been performed at neutral pH. Irreversible bi- or tetra-electronic processes are observed for these substances, and the electron transfer coefficient (αn) calculated. It was concluded that either the first or second electron transfer were the rate determining step of the electrode process. The diffusion coefficient of these substances was calculated and the values given follow an inverse tendency to the molecular size. For aldehydes the values obtained were corrected of the hydration reaction. It is important to remark that catalytic waves were reported for the first time for these compounds. Using a model involving the nitrogen of the basic structure the kinetic constants were calculated for most of them

    A Method to Estimate the Boson Mass and to Optimise Sensitivity to Helicity Correlations of tau+tau- Final States

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    In proton-proton collisions at LHC energies, Z and low mass Higgs bosons would be produced with high and predominantly longitudinal boost with respect to the beam axis. This note describes a new analysis tool devised to handle this situation in cases when such bosons decay to a pair of tau-leptons. The tool reconstructs the rest frame of the tau+tau- pair by finding the boost that minimises the acollinearity between the visible tau decay products. In most cases this gives a reasonable approximation to the rest frame of the decaying boson. It is shown how the reconstructed rest frame allows for a new method of mass estimation. Also a considerable gain in sensitivity to helicity correlations is obtained by analysing the tau-jets in the reconstructed frame instead of using the laboratory momenta and energies, particularly when both tau-leptons decay hadronically.Comment: 13 pages, method extended with 3D boost finde
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