6,853 research outputs found
Functional anatomy of non-REM sleep
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
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 photometry
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 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 m
and 12 m () with the corresponding synthetic value, derived
from results of classical model photospheres. We found a detection rate of
0.85 at 22 m (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
observations. As an additional result, we found that the fluxes
required a normalisation procedure to make them compatible with synthetic data,
probably pointing out a revision of the 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.
Sin resume
Soil, Water and Crop Management for Agricultural Profitability and Natural Resources Protection in Salt-Threatened Irrigated Lands
The arogenate dehydratase ADT2 is essential for seed development in Arabidopsis
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
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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