638 research outputs found
The rissaga of 15 June 2006 in Ciutadella (Menorca), a meteorological tsunami
An extraordinary "rissaga" event (the local name for high-amplitude sea level oscillations) with 4–5 m of amplitude occurred on 15 June 2006 at Ciutadella (Menorca, Spain). In this paper we describe the rissaga event and propose that the meteorological mechanism responsible for it was an unusual pressure jump, associated with a convective squall line
Role of electron-phonon coupling and thermal expansion on band gaps, carrier mobility, and interfacial offsets in kesterite thin-film solar cells
The efficiencies of solar cells based on kesterite Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe) are limited by a low open-circuit voltage due to high rates of non-radiative electron-hole recombination. To probe the origin of this bottleneck, we calculate the band offset of CZTS(Se) with CdS, confirming a weak spike of 0.1 eV for CZTS/wurtzite-CdS and a strong spike of 0.4 eV for CZTSe/wurtzite-CdS. We also consider the effects of temperature on the band alignment, finding that increasing temperature significantly enhances the spike-type offset. We further resolve an outstanding discrepancy between the measured and calculated phonon frequencies for the kesterites, and use these to estimate the upper limit of electron and hole mobilities based on optic phonon Fröhlich scattering, which uncovers an intrinsic asymmetry with faster (minority carrier) electron mobility.</jats:p
Histological study of the sex-change in the skunk clownfish <i>Amphiprion akallopisos</i>
Sex change in the protandrous fish Amphiprion akallopisos Bleeker, 1853 (F.Pomacentridae) has been analysed. Experiments consisted of placing males together after being separated from their mates, and observe changes in gonad histology at different periods, in order to identify signs of the sex change process. The presence of a first invagination on the male gonad wall, and the observation of the first cortical alveoli oocytes as an indication of the beginning of the vitellogenesis process, was the first symptom of the sex change, which has been detected after 18 days in one of the males. Period needed for the sex changing process was size independent. The process by which wall invagination is converted into ovarian lumen in the future mature ovary is also described
Pressure-induced transitions in FePS: Structural, magnetic and electronic properties
FePS is a prototype van der Waals layered antiferromagnet and a Mott
insulator under ambient conditions, which has been recently reported to go
through a pressure-induced dimensionality crossover and an insulator-to-metal
transition. These transitions also lead to the appearance of a novel magnetic
metallic state. To further understand these emergent structural and physical
properties, we have performed a first-principles study using van der Waals and
Hubbard corrected density functional theory including a random structure
search. Our computational study attempts to interpret the experimental
coexistence of the low- and intermediate-pressure phases and we predict a novel
high-pressure phase with distinctive dimensionality and different possible
origins of metallicity.Comment: Re-Submission to SciPos
A mesoscale index to describe the regional ocean circulation around the Balearic Islands
Historical oceanographic surveys carried out around the Balearic Islands (western Mediterranean) suggest two different scenarios for the regional ocean circulation. In one scenario, occurring during cold winters, cool water is formed at intermediate layers (100–300 m) in the Gulf of Lions. This Western Mediterranean Intermediate Water (WIW) usually moves southward reaching the Balearic Channels, deflecting the warmer Levantine Intermediate Water (LIW) coming from the Eastern Mediterranean, and even blocking the Ibiza Channel. On the other hand, during mild winters, less WIW is formed and then LIW flows through the channels, appearing at their characteristic depths. The oceanographic surveys around the Balearic Islands (1985–2004) have provided a qualitative index, indicating the presence or not of WIW in the Ibiza Channel, based on the analyses of θS diagrams. A quantitative index based on mean water temperature between 100 and 300 m depth in the channels may also be defined. Both indexes, the qualitative and the quantitative, give consistent information on WIW presence for the period 1985–2004, however, both are short in time and have gaps in the series. In order to obtain a longer and continuous index for WIW presence and then for regional circulation, air–sea heat fluxes at the Gulf of Lions during winter months were obtained from the meteorological NCEP/NCAR reanalysis dataset and compared with other meteorological data such as surface air temperature. The standardized air temperature anomalies at 1000 hPa in the Gulf of Lions during winter (December–March) has been shown to be the simplest and best indicator of absence/presence of WIW in the Balearic Islands channels in late spring. Values above 1.0 of the standardized temperature anomaly would indicate absence of WIW in the Ibiza Channel. The high correlation obtained with available in-situ oceanographic data allows the use of this index as an indicator of presence of WIW and then of different regional circulation scenarios backwards in time and in those years for which the oceanographic data are missing or scarc
Los visitantes del Parc Natural de l’Alt Pirineu y la práctica de actividades recreativo-deportivas. una propuesta de segmentación
In recent years there has been a large increase in the practice of recreational and sports activities in protected natural areas. As part of the planning and management of public use of these areas, is essential to a deeper understanding of the characteristics of the visitors. This study analyzes the characteristics of the different segments of visitors to Alt Pirineu Natural Park based on recreational and sports activities practiced. For this study, 1.600 surveys were conducted in 16 sampling points over a calendar year between the months of July 2010 and June 2011. In total we identified eight segments of visitors based on physical activity: walkers, recreational hikers, hikers, mountaineer, cyclists, mushroom picker, off road driver and skier. The results obtained here are discussed in terms of their possible applicability in the management of public use of this park and other protected natural areas and also for the development of management strategies and awareness campaigns aimed at different segments of visitors.En los últimos años se ha registrado un gran incremento en la práctica de las actividades recreativodeportivas en los espacios naturales protegidos. En el marco de la planificación y la gestión del uso público de este tipo de espacios, resulta fundamental profundizar en el conocimiento de las características de los visitantes. En este estudio se analiza el perfil de los diferentes segmentos de visitantes del Parc Natural de l’Alt Pirineu en base a las actividades recreativo-deportivas practicadas. Para este estudio se realizaron 1.600 encuestas en 16 puntos de muestreo, a lo largo de un año natural comprendido entre los meses de Julio de 2010 y Junio de 2011. En total se identificaron ocho segmentos de visitantes en función de la actividad física: paseantes, excursionistas, senderistas, montañistas, ciclistas, recolectores de setas, motoristas y esquiadores. Los resultados aquí obtenidos son discutidos en términos de su posible aplicación en la gestión del uso público de este parque (extrapolable también a otros espacios naturales protegidos españoles), proponiendo estrategias de gestión y campañas de sensibilización dirigidas a los diferentes segmentos de visitantes
Los visitantes del Parc Natural de l’Alt Pirineu y la práctica de actividades recreativo-deportivas. una propuesta de segmentación
In recent years there has been a large increase in the practice of recreational and sports activities in protected natural areas. As part of the planning and management of public use of these areas, is essential to a deeper understanding of the characteristics of the visitors. This study analyzes the characteristics of the different segments of visitors to Alt Pirineu Natural Park based on recreational and sports activities practiced. For this study, 1.600 surveys were conducted in 16 sampling points over a calendar year between the months of July 2010 and June 2011. In total we identified eight segments of visitors based on physical activity: walkers, recreational hikers, hikers, mountaineer, cyclists, mushroom picker, off road driver and skier. The results obtained here are discussed in terms of their possible applicability in the management of public use of this park and other protected natural areas and also for the development of management strategies and awareness campaigns aimed at different segments of visitors.<br><br>En los últimos años se ha registrado un gran incremento en la práctica de las actividades recreativodeportivas en los espacios naturales protegidos. En el marco de la planificación y la gestión del uso público de este tipo de espacios, resulta fundamental profundizar en el conocimiento de las características de los visitantes. En este estudio se analiza el perfil de los diferentes segmentos de visitantes del Parc Natural de l’Alt Pirineu en base a las actividades recreativo-deportivas practicadas. Para este estudio se realizaron 1.600 encuestas en 16 puntos de muestreo, a lo largo de un año natural comprendido entre los meses de Julio de 2010 y Junio de 2011. En total se identificaron ocho segmentos de visitantes en función de la actividad física: paseantes, excursionistas, senderistas, montañistas, ciclistas, recolectores de setas, motoristas y esquiadores. Los resultados aquí obtenidos son discutidos en términos de su posible aplicación en la gestión del uso público de este parque (extrapolable también a otros espacios naturales protegidos españoles), proponiendo estrategias de gestión y campañas de sensibilización dirigidas a los diferentes segmentos de visitantes
Evaluación mediante simulación de nuevos sistemas para mantener la separación de a bordo en vuelo de crucero en forma automática o asistida
Para no comprometer la seguridad operacional, son importantes los sistemas con corrección automáticos de vigilancia embarcados, minimizando riesgos en el “control de tráfico aéreo”, facilitando así a las tripulaciones, información actualizada, permanente con correcciones automáticas en tiempo real. Este trabajo presenta el modelo, el simulador y los estudios realizados para evaluar la adaptabilidad de las tripulaciones ante un sistema totalmente automatizado, mediante el “piloto automático”, realizando las maniobras requeridas evitando conflictos con los tráficos circundantes y mantener la separación en vuelo crucero.To avoid compromising safety, on board automatic correction systems are important, minimizing risks in air traffic control, providing crews with updated information, permanent with real-time automatic corrections. This paper presents the model, the simulator and studies to evaluate the adaptability of the crews to a fully automated system, using the "automatic pilot", performing the required maneuvers avoiding conflicts with surrounding traffic and maintaining separation in cruising flight.Grupo de Transporte Aéreo - Grupo de Ingeniería Aplicada a la Industri
Estudio de la adaptabilidad de tripulaciones a un nuevo sistema automático inteligente para mantener separación de a bordo, en vuelo crucero, mediante el uso de simulacion
En la seguridad operacional son importantes los sistemas embarcados para la vigilancia y resolución de conflictos, con correcciones automáticas para mantener la separación de a bordo minimizando los riesgos en el “control de tráfico aéreo”, brindando a las tripulaciones información en tiempo real.
OACI (Organización Internacional de Aviación Civil), definió el ASAS (sistema de asistencia de separación de a bordo), como: un sistema de aeronave para la vigilancia de a bordo, asistiendo a la tripulación en vuelo para mantener la separación de su aeronave con respecto a otras del entorno; permitiendo vigilancia de a bordo, sustentada por la ADS-B (automatic dependent surveillancebroadcast.), la TIS-B (traffic information services-broadcast), y el TCAS (sistema anticolisión de alerta de tráfico). Esta vigilancia es realizada por un nuevo sistema automatizado, denominado “Sim CDTI” (simulator CDTI). El A/P (autopilot), realiza las maniobras para mantener la separación horizontal y vertical, evitando predictivamente conflictos. Se presentan las evaluaciones de adaptabilidad de las tripulaciones ante un sistema automatizado, donde el A/P ejecuta maniobras adecuadas para mantener la separación y evitar conflictos. Se evalúa que la seguridad operacional no es infringida con este sistema, presentándose el desarrollo de un simulador para tal fin.Facultad de Ingenierí
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