953 resultados para skilled labor


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Acknowledgements We are grateful to Elaine O’Mahony, Imogen Pearce, Richard Comont, Anthony McCluskey and other BBCT staff for the many hours of BeeWatch species identification and for all people who submitted sightings to BeeWatch, OPAL, BWARS and the various local recording schemes and societies. We thank the NBN for allowing us to download the bumblebee records without strings attached, and the Essex, Greater London, Cumbria and Sussex based recording centres for providing records upon request. Finally, we are indebted to Tom August and two anonymous reviewers for their valuable critique on an earlier version of this work.

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Contact of cultured mammary epithelial cells with the basement membrane protein laminin induces multiple responses, including cell shape changes, growth arrest, and, in the presence of prolactin, transcription of the milk protein β-casein. We sought to identify the specific laminin receptor(s) mediating the multiple cell responses to laminin. Using assays with clonal mammary epithelial cells, we reveal distinct functions for the α6β4 integrin, β1 integrins, and an E3 laminin receptor. Signals from laminin for β-casein expression were inhibited in the presence of function-blocking antibodies against both the α6 and β1 integrin subunits and by the laminin E3 fragment. The α6-blocking antibody perturbed signals mediated by the α6β4 integrin, and the β1-blocking antibody perturbed signals mediated by another integrin, the α subunit(s) of which remains to be determined. Neither α6- nor β1-blocking antibodies perturbed the cell shape changes resulting from cell exposure to laminin. However, the E3 laminin fragment and heparin both inhibited cell shape changes induced by laminin, thereby implicating an E3 laminin receptor in this function. These results elucidate the multiplicity of cell-extracellular matrix interactions required to integrate cell structure and signaling and ultimately permit normal cell function.

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We report the isolation and expression of the Hox gene, Cnox-2, in Hydractinia symbiolongicarpus, a hydrozoan displaying division of labor. We found different patterns of aboral-to-oral Cnox-2 expression among polyp polymorphs, and we show that experimental conversion of one polyp type to another is accompanied by concordant alteration in Cnox-2 expression. Our results are consistent with the suggestion that polyp polymorphism, characteristic of hydractiniid hydroids, arose via evolutionary modification of proportioning of head to body column.

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Behavioral and neurophysiological studies suggest that skill learning can be mediated by discrete, experience-driven changes within specific neural representations subserving the performance of the trained task. We have shown that a few minutes of daily practice on a sequential finger opposition task induced large, incremental performance gains over a few weeks of training. These gains did not generalize to the contralateral hand nor to a matched sequence of identical component movements, suggesting that a lateralized representation of the learned sequence of movements evolved through practice. This interpretation was supported by functional MRI data showing that a more extensive representation of the trained sequence emerged in primary motor cortex after 3 weeks of training. The imaging data, however, also indicated important changes occurring in primary motor cortex during the initial scanning sessions, which we proposed may reflect the setting up of a task-specific motor processing routine. Here we provide behavioral and functional MRI data on experience-dependent changes induced by a limited amount of repetitions within the first imaging session. We show that this limited training experience can be sufficient to trigger performance gains that require time to become evident. We propose that skilled motor performance is acquired in several stages: “fast” learning, an initial, within-session improvement phase, followed by a period of consolidation of several hours duration, and then “slow” learning, consisting of delayed, incremental gains in performance emerging after continued practice. This time course may reflect basic mechanisms of neuronal plasticity in the adult brain that subserve the acquisition and retention of many different skills.

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Temporal polyethism is a highly derived form of behavioral development displayed by social insects. Hormonal and genetic mechanisms regulating temporal polyethism in worker honey bees have been identified, but the evolution of these mechanisms is not well understood. We performed three experiments with male honey bees (drones) to investigate how mechanisms regulating temporal polyethism may have evolved because, relative to workers, drones display an intriguing combination of similarities and differences in behavioral development. We report that behavioral development in drones is regulated by mechanisms common to workers. In experiment 1, drones treated with the juvenile hormone (JH) analog methoprene started flying at significantly younger ages than did control drones, as is the case for workers. In experiment 2, there was an age-related increase in JH associated with the onset of drone flight, as in workers. In experiment 3, drones derived from workers with fast rates of behavioral development themselves started flying at younger ages than drones derived from workers with slower rates of behavioral development. These results suggest that endocrine and genetic mechanisms associated with temporal polyethism did not evolve strictly within the context of worker social behavior.

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In the period 1999-2007 Spanish imports from China multiplied by six, making that Asian country the fourth largest supplier to the Spanish economy. In this paper, we analyse whether this massive increase in imports impacted on the labour markets of Spanish provinces to differing degrees, due to differences in their initial productive specialization. Our results show that Spanish provinces with a higher exposure to Chinese imports experienced larger drops in manufacturing employment as a share of the working-age population. However, this reduction was compensated for by increases in non-manufacturing employment.

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La migración española de la segunda mitad del siglo XX se ha caracterizado en un primer momento por su carácter masivo y poco cualificado, seguido por un interregno de procesos de retorno y finalmente por una migración estable, no masiva pero altamente cualificada. La atención prestada a la inmigración masiva que recibe España a finales del siglo XX relegó a un segundo plano esta emigración cualificada de españoles. En este artículo se considera la relación entre movilidad espacial (migración de españoles) y su posible consecuencia sobre la movilidad social ascendente que experimentan. Para ello se utilizan los datos procedentes de la encuesta internacional EIMSS (European Internal Migrations Social Survey) y los procedimientos de escalamiento de clase social basados en la ocupación de Goldthorpe. El análisis se complementa con una simulación sobre la movilidad de clase, con la finalidad de visualizar y comparar los efectos sobre la movilidad social de la emigración de españoles a Francia, Alemania, Italia y Gran Bretaña.

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En el presente artículo revisamos el trabajo etnográfico que un misionero franciscano del siglo XVI, fray Jerónimo de Alcalá, realizó por medio de la traducción. Su principal obra, la Relación de Michoacán, constituye uno de los más valiosos manuscritos coloniales de toda América. Para su elaboración recopiló, tradujo y fijó en el papel la tradición oral purépecha, rescatando del olvido el testimonio histórico y antropológico de la riqueza cultural michoacana. El rigor científico de su trabajo de campo, que acometió humildemente como “fiel intérprete” y con mera intención misional, ha hecho de su obra una fuente documental imprescindible.

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Es un lugar común afirmar que una de las repercusiones positivas del desarrollo turístico es la facilitación de la incorporación de la mujer al mundo laboral. Así, las mujeres representan la mayor parte de la fuerza de trabajo del sector hostelero español y están representadas en todas las categorías laborales. Sin embargo, se sabe que dicha incorporación se realiza en condiciones desiguales y, específicamente en los hoteles, las mujeres ocupan mayoritariamente puestos de baja cualificación. También es un lugar común que una de las claves para el éxito del sector turístico es asegurar que los trabajadores sean eficientes y estén comprometidos con la empresa para garantizar la calidad del servicio prestado. Las políticas laborales deben promover una mayor igualdad de oportunidades, remuneración y condiciones de trabajo en el sector. En este trabajo se presentan evidencias de la disparidad salarial, la segregación vertical y la mayor precariedad laboral que sufren las mujeres en el subsector de la hostelería en España. Con este propósito se analizan datos estadísticos secundarios procedentes de organismos oficiales. Finalmente, se propone una reflexión acerca de las razones que motivan estas desigualdades, así como de las políticas que deberían seguirse para mitigarlas.

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by W. Jett Lauck and Edgar Sydenstricker.

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by Isaac A. Hourwich.

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by Mabel Brown Ellis.