13,041 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
Some remarks on the comparison principle in Kirchhoff equations
In this paper we study the validity of the comparison principle and the sub-supersolution method for Kirchhoff type equations. We show that these principles do not work when the Kirchhoff function is increasing, contradicting some previous results. We give an alternative sub-supersolution method and apply it to some models.Conselho Nacional de Desenvolvimento Científico e TecnológicoMinisterio de Economía y Competitivida
Grasping bulky objects with two anthropomorphic hands
© 2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksThis paper presents an algorithm to compute precision grasps for bulky objects using two anthropomorphic hands. We use objects modeled as point clouds obtained from a sensor camera or from a CAD model. We then process the point clouds dividing them into two set of slices where we look for sets of triplets of points. Each triplet must accomplish some physical conditions based on the structure of the hands. Then, the triplets of points from each set of slices are evaluated to find a combination that satisfies the force closure condition (FC). Once one valid couple of triplets have been found the inverse kinematics of the system is computed in order to know if the corresponding points are reachable by the hands, if so, motion planning and a collision check are performed to asses if the final grasp configuration of the system is suitable. The paper
inclu des some application examples of the proposed approachAccepted versio
Impact assessment of a new parking pricing écheme in Madrid city centre.
Ponencia en Congres
Strategic assessment of transport infrastructure Plans on European integration. Application for the Spanish Strategic Transport and Infrastructure Plan 2005-2020
Traditional transport infrastructure assessment methodologies rarely include the full range of strategic benefits for the transportation system. One of these benefits is the contribution to cross-border integration. However, this is a key issue in strategic planning and decision-making processes, as its inclusion may increase the probability of large-scale transport infrastructure projects being funded. This paper presents a methodology for the measurement of the contribution of Transport Infrastructure Plans to cross-border integration. The methodology is based on the measurement of the improvement in network efficiency in cross-border regions of neighboring countries, via accessibility calculations in a Geographical Information System (GIS) support. The methodology was tested by applying it to the ambitious road and rail network extensions included in the Spanish Strategic Transport and Infrastructure Plan (PEIT) 2005-2020. The results show significant and important network efficiency improvements of the PEIT outside the Spanish border. For the road mode, while the Spanish average accessibility improvement accounts for 2.6%, average improvements in cross-border regions of France and Portugal are of 1.8%. And for the rail mode, the corresponding Spanish value is 34.5%, whereas in neighboring regions it accounts for 20.2%. These results stress the significant importance of this strategic benefit and the consequent need for its inclusion in strategic planning processes. Finally, the paper identifies the potential of the methodology when applied at different administrative levels, such as the local or state levels
Caracterización genómica y fisiológica de la capacidad degradadora de hidrocarburos aromáticos de Citreicella aestuarii 357
La cepa 357 fué aislada en el año 2002 de una muestra de arena (Praia da Seda,Galicia, España) contaminada con petróleo del Prestige. Esta cepa, presuntamente afiliada al grupo Roseobacter, fue capaz de crecer utilizando naftaleno como única fuente de carbono y energía. Ante la falta de información genética y bioquímica sobre degradación de naftaleno en el grupo Roseobacter, decidimos abordar el trabajo presentado en esta tesis. Así, se ha confirmado taxonómicamente la afiliación de la cepa 357 a la especie Citreicella aestuarii. A continuación, utilizando técnicas genómicas, fisiológicas y analíticas, se ha caracterizado el potencial metabólico de la cepa 357 en el contexto del grupo Roseobacter. Además, se ha definido fisiológica, genética y bioquímicamente la vía catabólica del naftaleno. Así, C. aestuarii 357 es capaz de metabolizar el naftaleno vía salicilato y gentisato. Adicionalmente, hemos demostrado la capacidad de la cepa 357 de crecer con dibenzotiofeno como fuente única de carbono, energía y azufre.Strain 357 was isolated in 2002 from an oil-polluted sand sample from Praia da Seda (Galicia, Spain). This strain, a plausible member of the Roseobacter clade, was able to grow using naphthalene as sole carbon and energy source. Due to the lack of genetic and biochemical information about naphthalene degradation in Roseobacter, the work presented in this PhD Thesis was started. Thus, it has been taxonomically demonstrated that strain 357 is a member of the Citreicella aestuarii species. Using physiology, genomic and analytical techniques the metabolic potential of strain 357 in the context of the Roseobacter clade has been characterized. Furthermore, it has been demonstrated that C. aestuarii 357 is able to metabolize naphthalene via salicylate and gentisate. Finally, it has been proven that strain 357 is able to use dibenzothiophene as unique carbon, energy and sulfur source
Water maser detections in southern candidates to post-AGB stars and Planetary Nebulae
We intended to study the incidence and characteristics of water masers in the
envelopes of stars in the post-AGB and PN evolutionary stages.
We have used the 64-m antenna in Parkes (Australia) to search for water maser
emission at 22 GHz, towards a sample of 74 sources with IRAS colours
characteristic of post-AGB stars and PNe, at declination . In our
sample, 39% of the sources are PNe or PNe candidates, and 50% are post-AGB
stars or post-AGB candidates.
We have detected four new water masers, all of them in optically obscured
sources: three in PNe candidates (IRAS 12405-6219, IRAS 15103-5754, and IRAS
16333-4807); and one in a post-AGB candidate (IRAS 13500-6106). The PN
candidate IRAS 15103-5754 has water fountain characteristics, and it could be
the first PN of this class found.
We confirm the tendency suggested in Paper I that the presence of water
masers in the post-AGB phase is favoured in obscured sources with massive
envelopes. We propose an evolutionary scenario for water masers in the post-AGB
and PNe stages, in which ``water fountain'' masers could develop during
post-AGB and early PN stages. Later PNe would show lower velocity maser
emission, both along jets and close to the central objects, with only the
central masers remaining in more evolved PNe.Comment: 11 pages, 5 figures. Accepted by Astronomy and Astrophysic
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