9,337 research outputs found
Comunicación, ciencia, desarrollo y tercer mundo
En el present treball es pretén identificar i analitzar el paper de diversos factors que les modernes tecnologies de la informació, la comunicació i la documentació han anat introduint com a elements potencials per a desenvolupar-se i autosostenir-se en un dels sectors més desatesos en els països del Tercer Món: la formació tecnicocientífica i la recerca. Es mostra el perfil d'alguns dels actors que intervenen des del Primer Món i es du a terme un procés de convergència de tots aquests actors cap a una autèntica comunitat científica virtual internacional, amb la complicitat del fenomen Internet com a fons conceptual i pragmàtic.This paper tries to identify and analize the role of several factors coming from the modern information, communication and documentation technologies. These factors have been proposed as agents to promote and enhance the development and sustainability processes in one of the most underdeveloped sectors in Third World countries: the scientific revolution. Some of the actors, coming from the Developed World, are subject of shaping and convergence processes towards the formation of a true scientific virtual international community with the omnipresent aid, in the end, of Internet as both conceptual and pragmatic background.En el presente trabajo se intentan identificar y analizar el papel de diversos factores que las modernas tecnologías de la información, la comunicación y la documentación han ido introduciendo como elementos potenciales para el desarrollo y la autosostenibilidad en uno de los sectores más desatendidos en los países del Tercer Mundo: la formación tecnicocientífica y la investigación. Se muestra el perfil de algunos de los actores que intervienen desde el Primer Mundo y se hace un proceso de convergencia de todos ellos hacia una auténtica comunidad científica virtual internacional con la complicidad del fenómeno Internet como fondo conceptual y pragmático
Sustainable Planning of Land Use Changes in farming areas under ecological protection
Land use has been changing in the last decades because of agricultural intensification and land abandonment which implies deterioration in the optimum habitat structure and quality. Habitat degradation and loss, resulting from changes in land use remain significant drivers of biodiversity loss. These trends are widely recognised and have forced national and international agencies to identify protected sites for natural areas with high biodiversity value. Special Protection Areas (SPAs) are natural zones particularly relevant for nature conservation. Regional planning is bound to play an increasing role in nature conservation policies because much biodiversity is located in farming areas outside natural parks. Agriculture in the Mediterranean Basin has always been highly dependent on rainfed crops, cereal, vine and olive. Vine growing plays an important role not only from the economic point of view, but also environmentally as a permanent plant cover in terms of preventing erosion, managing land and water resources in a sustainable way, defending against desertification an settling population in rural areas. A Geographic Information System (GIS) was used to implement a decision tool system to analyse the feasibility of new proposals to upgrade traditional vineyards in Castilla-La Mancha, Spain. The study focuses on the sustainability of current farming practices in Special Protection Areas for Steppe Land Birds. This paper presents a model to quantify the resulting habitat fragmentation basing on infrastructure facilities, leading to mapping areas where to apply restriction measures to prevent physical destruction of the habita
Thermal diagnostic of the Optical Window on board LISA Pathfinder
Vacuum conditions inside the LTP Gravitational Reference Sensor must comply
with rather demanding requirements. The Optical Window (OW) is an interface
which seals the vacuum enclosure and, at the same time, lets the laser beam go
through for interferometric Metrology with the test masses. The OW is a
plane-parallel plate clamped in a Titanium flange, and is considerably
sensitive to thermal and stress fluctuations. It is critical for the required
precision measurements, hence its temperature will be carefully monitored in
flight. This paper reports on the results of a series of OW characterisation
laboratory runs, intended to study its response to selected thermal signals, as
well as their fit to numerical models, and the meaning of the latter. We find
that a single pole ARMA transfer function provides a consistent approximation
to the OW response to thermal excitations, and derive a relationship with the
physical processes taking place in the OW. We also show how system noise
reduction can be accomplished by means of that transfer function.Comment: 20 pages, 14 figures; accepted for publication in Class. Quantum Gra
Quantum Phase Transitions in the Interacting Boson Model: Integrability, level repulsion and level crossing
We study the quantum phase transition mechanisms that arise in the
Interacting Boson Model. We show that the second-order nature of the phase
transition from U(5) to O(6) may be attributed to quantum integrability,
whereas all the first-order phase transitions of the model are due to level
repulsion with one singular point of level crossing. We propose a model
Hamiltonian with a true first-order phase transition for finite systems due to
level crossings.Comment: Accepted in PR
Overview of ASDEX Upgrade results
The ASDEX Upgrade (AUG) programme is directed towards physics input to critical
elements of the ITER design and the preparation of ITER operation, as well as addressing
physics issues for a future DEMO design. Since 2015, AUG is equipped with a new pair of
3-strap ICRF antennas, which were designed for a reduction of tungsten release during ICRF
operation. As predicted, a factor two reduction on the ICRF-induced W plasma content could
be achieved by the reduction of the sheath voltage at the antenna limiters via the compensation
of the image currents of the central and side straps in the antenna frame. There are two main
operational scenario lines in AUG. Experiments with low collisionality, which comprise
current drive, ELM mitigation/suppression and fast ion physics, are mainly done with freshly
boronized walls to reduce the tungsten influx at these high edge temperature conditions. Full
ELM suppression and non-inductive operation up to a plasma current of Ip = 0.8 MA could
be obtained at low plasma density. Plasma exhaust is studied under conditions of high neutral
divertor pressure and separatrix electron density, where a fresh boronization is not required.
Substantial progress could be achieved for the understanding of the confinement degradation
by strong D puffing and the improvement with nitrogen or carbon seeding. Inward/outward
shifts of the electron density profile relative to the temperature profile effect the edge stability
via the pressure profile changes and lead to improved/decreased pedestal performance.
Seeding and D gas puffing are found to effect the core fueling via changes in a region of high
density on the high field side (HFSHD).
The integration of all above mentioned operational scenarios will be feasible and
naturally obtained in a large device where the edge is more opaque for neutrals and higher
plasma temperatures provide a lower collisionality. The combination of exhaust control
with pellet fueling has been successfully demonstrated. High divertor enrichment values of
nitrogen EN 10 have been obtained during pellet injection, which is a prerequisite for the
simultaneous achievement of good core plasma purity and high divertor radiation levels.
Impurity accumulation observed in the all-metal AUG device caused by the strong neoclassical
inward transport of tungsten in the pedestal is expected to be relieved by the higher
neoclassical temperature screening in larger devices.European Commission (EUROfusion 633053
Tornillos expansivos: Un recurso en la artrodesis lumbosacra
En los últimos años han aparecido numerosos sistemas de fijación transpedicular que han hecho evolucionar a esta técnica. En 1991 se diseñó el sistema OMEGA 21 que permite la posibilidad de utilización de tornillos expansivos en artrodesis lumbosacra: un caso de fractura estallido, una fractura patológica en el seno de una columna osteoporótica, una cirugía de revisión en una fractura vertebral y un caso de desmontaje de un sistema de fijación transpedicular. En total fueron colocados 11 tornillos expansivos apareciendo la rotura de uno de ellos a los 15 meses. El tornillo expansivo permite la utilización de la fijación transpedicular en situaciones especiales, teniendo dos indicaciones precisas: casos con osteoporosis grave y cirugía de revisión.In recent years numerous pedicular fixation systems have appeared, revolutionizing the technique. In 1991, the OMEGA-21 system was designed to allow the use of expansive screws in lumbosacral arthrodesis: one burst fracture, one pathologic fracture in an osteoporotic spine, one revision surgery of a vertebral fracture and one disassembly of a pedicular fixation system. In total, 11 expansive screws were placed, one of them appearing broken 15 months after implantation. Expansive screws allows the use of pedicular fixation in special situations, having two precise indications: severe osteoporosis and revision surgery
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