2,271 research outputs found

    Observation and analysis of Etesian wind storms in the Saroniko Gulf

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    The purpose of this work is to study the Etesian winds in the Saroniko Gulf to understand the complicate physical processes that generate the windstorms in the Saroniko Gulf. It is developed a study of the weather patterns characteristic of the Saroniko Gulf and a comparisons of the wind data measured on land by the station of Helliniko airport (years: 1990-2000) and at sea by a buoy (years: 2000- 2002) during the month of August. It is presented a statistical model that shows, as a probability of occurrence, the variations of the wind speed in function of the variations of the wind direction. Finally the statistical model is compared with the RAMS limited area model during a test case in August 2004; the now-casting results obtained using these two different methods are compared to data measured by station of the automatic weather network of the HNM

    Ground-state properties of the disordered Hubbard model in two dimensions

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    We study the interplay between electron correlation and disorder in the two-dimensional Hubbard model at half-filling by means of a variational wave function that can interpolate between Anderson and Mott insulators. We give a detailed description of our improved variational state and explain how the physics of the Anderson-Mott transition can be inferred from equal-time correlations functions, which can be easily computed within the variational Monte Carlo scheme. The ground-state phase diagram is worked out in both the paramagnetic and the magnetic sector. Whereas in the former a direct second-order Anderson-Mott transition is obtained, when magnetism is allowed variationally, we find evidence for the formation of local magnetic moments that order before the Mott transition. Although the localization length increases before the Mott transition, we have no evidence for the stabilization of a true metallic phase. The effect of a frustrating next-nearest-neighbor hopping tt^\prime is also studied in some detail. In particular, we show that tt^\prime has two primary effects. The first one is the narrowing of the stability region of the magnetic Anderson insulator, also leading to a first-order magnetic transition. The second and most important effect of a frustrating hopping term is the development of a ``glassy'' phase at strong couplings, where many paramagnetic states, with disordered local moments, may be stabilized.Comment: 13 pages and 16 figure

    Numerical simulations of strong wind situations near the Mediteranean French Coast: comparison with FETCH data

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    A detailed analysis is made of some typical strong wind situations near the French Mediterranean coast. Special attention has been paid to the wind from the north-northwest in the Gulf of Lion, also called the mistral. The analysis is made from both the synoptic and mesoscale point of view with the aid of numerical simulations carried out with the Regional Atmospheric Modeling System (RAMS) to study the main atmospheric, climatic, and meteorological characteristics of this wind in the Gulf of Lion. Simulations were made with this model during the periods of 20-22 March and 24-26 March 1998. Afterward, a comparison was made with the meteorological measurements collected during the international Flux, Etat de la Mer et Te´le´de´tection en Condition de Fetch Variable (FETCH) campaign (Gulf of Lion, March-April 1998). The comparison between the simulated wind fields and the values measured by the coastal meteorological stations, an oceanographic buoy, and the ship Atalante at sea help to give full understanding of the complicated physical processes that characterize strong wind situations in coastal zone

    Temperature-dependent photoluminescence characteristics of GeSn epitaxial layers

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    GeSn epitaxial heterostructures are emerging as prominent candidates for the monolithic integration of light sources on Si substrates. Here we propose a judicious explanation for their temperature-dependent photoluminescence (PL) that is based upon the so far disregarded optical activity of dislocations. By working at the onset of plastic relaxation, which occurs whenever the epilayer releases the strain accumulated during growth on the lattice mismatched substrate, we demonstrate that dislocation nucleation can be explicitly seen in the PL data. Notably, our findings point out that a monotonous thermal PL quenching can be observed in coherent films, in spite of the indirect nature of the GeSn bandgap. Our investigation, therefore, contributes to a deeper understanding of the recombination dynamics in this intriguing group IV alloy and offers insights into crucial phenomena shaping the light emission efficiency

    Differences in health symptoms among residents living near illegal dump sites in Los Laureles Canyon, Tijuana, Mexico: a cross sectional survey.

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    Living near landfills is a known health hazard prompting recognition of environmental injustice. The study aim was to compare self-reported symptoms of ill health among residents of four neighborhoods, living in haphazardly constructed settlements surrounded by illegal dumpsites in Tijuana, Mexico. One adult from each of 388 households located in Los Laureles Canyon were interviewed about demographics, health status, and symptoms. Distance from each residence to both the nearest dumpsite and the canyon bottom was assessed. The neighborhoods were selected from locations within the canyon, and varied with respect to proximity to dump sites. Residents of San Bernardo reported significantly higher frequencies of ill-health symptoms than the other neighborhoods, including extreme fatigue (OR 3.01 (95% CI 1.6-5.5)), skin problems/irritations (OR 2.73 (95% CI 1.3-5.9)), stomach discomfort (OR 2.47 (1.3-4.8)), eye irritation/tears (OR 2.02 (1.2-3.6)), and confusion/difficulty concentrating (OR 2.39 (1.2-4.8)). Proximity to dumpsites did not explain these results, that varied only slightly when adjusted for distance to nearest dumpsite or distance to the canyon bottom. Because San Bernardo has no paved roads, we hypothesize that dust and the toxicants it carries is a possible explanation for this difference. Studies are needed to further document this association and sources of toxicants

    Neutron magnetic form factor in strongly correlated materials

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    We introduce a formalism to compute the neutron magnetic form factor Fm(q) within a first-principles Density Functional Theory (DFT) + Dynamical Mean Field Theory (DMFT). The approach treats spin and orbital interactions on the same footing and reduces to earlier methods in the fully localized or the fully itinerant limit. We test the method on various actinides of current interest NpCoGa5, PuSb and PuCoGa5; we show that PuCoGa5 is in mixed valent state, which naturally explains the measured magnetic form factor.Comment: 4 pages with additional 4 pages of supplementary materia

    Le stationnement à Besançon

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    Depuis les années 1950, le recours à l'automobile pour de courts trajets quotidiens ne cesse de croître au détriment des autres moyens de transport, ce qui occasionne divers désagréments :encombrements qui engendrent la disparition des fonctions sociales de la rue, atteintes à l'environnement urbain qui dégradent la qualité de vie, accidents de la route générés par la densité et la rapidité du trafic
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