6,853 research outputs found

    Functional anatomy of non-REM sleep

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    The state of non-REM sleep (NREM), or slow wave sleep, is associated with a synchronized EEG pattern in which sleep spindles and/or K complexes and high-voltage slow wave activity (SWA) can be recorded over the entire cortical surface. In humans, NREM is subdivided into stages 2 and 3–4 (presently named N3) depending on the proportions of each of these polygraphic events. NREM is necessary for normal physical and intellectual performance and behavior. An overview of the brain structures involved in NREM generation shows that the thalamus and the cerebral cortex are absolutely necessary for the most significant bioelectric and behavioral events of NREM to be expressed; other structures like the basal forebrain, anterior hypothalamus, cerebellum, caudal brain stem, spinal cord and peripheral nerves contribute to NREM regulation and modulation. In NREM stage 2, sustained hyperpolarized membrane potential levels resulting from interaction between thalamic reticular and projection neurons gives rise to spindle oscillations in the membrane potential; the initiation and termination of individual spindle sequences depends on corticothalamic activities. Cortical and thalamic mechanisms are also involved in the generation of EEG delta SWA that appears in deep stage 3–4 (N3) NREM; the cortex has classically been considered to be the structure that generates this activity, but delta oscillations can also be generated in thalamocortical neurons. NREM is probably necessary to normalize synapses to a sustainable basal condition that can ensure cellular homeostasis. Sleep homeostasis depends not only on the duration of prior wakefulness but also on its intensity, and sleep need increases when wakefulness is associated with learning. NREM seems to ensure cell homeostasis by reducing the number of synaptic connections to a basic level; based on simple energy demands, cerebral energy economizing during NREM sleep is one of the prevalent hypotheses to explain NREM homeostasis.Grant BFU2009-06991/BFI from the Spanish Ministry of Science and Innovation supported this wor

    Aprend.e: sistema electrónico de aprendizagem para o ensino e formação profissional

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    Este artigo pretende demonstrar o impacto e relevância da plataforma Aprend.e como instrumento de dinamização no Programa Aveiro Norte e Escola Superior Aveiro Norte. Inicialmente esta plataforma surgiu como uma ferramenta de gestão e administração do Programa Aveiro Norte, com o objectivo de simplificar e automatizar processos relacionados com todas as actividades formativas do programa. Com o decorrer de actividades formativas, as tarefas de gestão orçamental relativas aos formadores e formandos, tornaram-se simples e funcionais, tendo como impacto imediato a redução de processos burocráticos assim como a diminuição significativa de tempo. Uma outra vertente desta plataforma é o apoio que pretende dar às actividades formativas, tanto aos formadores como formandos. Este apoio reflecte-se na disponibilização aos formandos, por parte dos formadores, da planificação das disciplinas, dos sumários, bem como os materiais de suporte às aulas. Como a literacia informática dos formadores é variada, o sistema de apoio aos formadores foi estruturado de modo a não haver pré-requisitos especiais na sua utilização, deste modo a própria disponibilização dos materiais de apoio às aulas é feita com um simples sistema de upload de ficheiros

    Infrared excesses in stars with and without planets using revised WISE{\it WISE} photometry

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    We present an analysis on the potential prevalence of mid infrared excesses in stars with and without planetary companions. Based on an extended database of stars detected with the WISE{\it WISE} satellite, we studied two stellar samples: one with 236 planet hosts and another with 986 objects for which planets have been searched but not found. We determined the presence of an excess over the photosphere by comparing the observed flux ratio at 22 μ\mum and 12 μ\mum (f22/f12f_{22}/f_{12}) with the corresponding synthetic value, derived from results of classical model photospheres. We found a detection rate of 0.85%\% at 22 μ\mum (2 excesses) in the sample of stars with planets and 0.1%\% (1 detection) for the stars without planets. The difference of the detection rate between the two samples is not statistically significant, a result that is independent of the different approaches found in the literature to define an excess in the wavelength range covered by WISE{\it WISE} observations. As an additional result, we found that the WISE{\it WISE} fluxes required a normalisation procedure to make them compatible with synthetic data, probably pointing out a revision of the WISE{\it WISE} data calibration.Comment: 10 pages, 6 figures, 3 tables. Accepted for publication in MNRA

    Early cannabinoid exposure as a source of vulnerability to opiate addiction: A model in laboratory rodents.

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    The arogenate dehydratase ADT2 is essential for seed development in Arabidopsis

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    Phenylalanine (Phe) biosynthesis in plants is a key process, as Phe serves as precursor of proteins and phenylpropanoids. The prephenate pathway connects chorismate, final product of the shikimate pathway, with the biosynthesis of Phe and Tyr. Two alternative routes of Phe biosynthesis have been reported: one depending of arogenate, and the other of phenylpyruvate. Whereas the arogenate pathway is considered the main route, the role of the phenylpyruvate pathway remains unclear. Here, we report that the deficiency in ADT2, a bifunctional arogenate dehydratase (ADT)/ prephenate dehydratase (PDT) enzyme, causes embryo arrest and seed abortion. This result makes a clear distinction between the essential role of ADT2 and the five remaining ADTs from Arabidopsis, which display mostly overlapping functions. We have found that PHA2, a monofunctional PDT from yeast, restores the adt2 phenotype when is targeted within the plastids, but not when is expressed in the cytosol. Similar results can be obtained by expressing ADT3, a monofunctional ADT. These results suggest that Phe can be synthesized from phenylpyruvate or arogenate when the bifunctional ADT2 is replaced by other ADT or PDT enzymes during seed formation, highlighting the importance of Phe for embryo development, and providing further insights into the plasticity of Phe biosynthesis.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Electrical Conductivity Measurements in Agriculture: The Assessment of Soil Salinity

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    Soil salinity is an important issue constraining the productivity of irrigation agriculture around the world. The standard method for soil salinity assessment is based on a laboratory method that is cumbersome and gives rise to limitations for data-intensive works. The use of sensors for the assessment of the apparent electrical conductivity (EC) of soils offers a way to overcome these constraints. These sensors are based on three electromagnetic phenomena, namely, electrical resistivity, electromagnetic induction, and reflectometry. Each class of sensors presents its own advantages and drawbacks. In the following chapter, these are presented along with the most popular commercial EC sensors used in nowadays agriculture, equations for the assessment of soil salinity on basis sensor measurements, some examples of application, and present and future development trends
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