University of the Littoral Opal Coast

About: University of the Littoral Opal Coast is a education organization based out in Dunkirk, France. It is known for research contribution in the topics: Catalysis & Dielectric. The organization has 1242 authors who have published 2383 publications receiving 46230 citations. The organization is also known as: ULCO.

Abordagem cognitiva de problemas de geometria em termos de congruência Approche cognitive des problèmes de geométrie en termes de congruence

Abstract: As atividades de construcao de figura foram desenvolvidas com base em um duplo objetivo: reintroduzir as figuras apos a reforma iconoclastica das matematicas modernas, que havia proibido de ver para compreender, e justificar didaticamente a necessidade de um vocabulario preciso para descrever, raciocinar e demonstrar. Mas, ver uma figura em geometria e uma atividade cognitiva mais complexa do que o simples reconhecimento daquilo que uma imagem mostra. Isto depende do papel que a figura tem na atividade matematica. Neste artigo, serao evidenciadas tres maneiras diferentes de ver as figuras segundo o seu papel: a apreensao perceptiva, a apreensao operatoria e a apreensao discursiva. Elas sao totalmente independentes umas das outras. A apreensao perceptiva e o reconhecimento visual imediato da forma. Preconizar-se-a o motivo pelo qual este reconhecimento impoe a nao modificacao apenas para certas formas, ao contrario de uma dada figura onde e possivel ocorrer alguma mudanca. A utilizacao de figuras para encontrar a solucao de um problema exige, ao contrario, que se possa transformar uma figura em outra. O presente trabalho mostra que diferentes tipos de operacoes visuais dao as figuras potencialidades heuristicas. A apreensao discursiva depende das hipoteses que a figura representa. Ela implica uma utilizacao de um vocabulario que e a condensacao das definicoes. A separacao destas tres apreensoes e fundamental para analisar a atividade geometrica e as dificuldades dos alunos. Por um lado, a resolucao de problemas exige que os alunos possam passar de um tipo a outro de apreensao. Por outro lado, a dificuldade dos problemas propostos depende dos fenomenos de congruencia entre os enunciados e a apreensao operatoria, assim como entre os enunciados e a apreensao discursiva.

Second-home owners and sea-level rise: the case of the Languedoc-Roussillon region (France)

Abstract: Municipalities of the Languedoc-Roussillon region (South-eastern France) are highly vulnerable to climate-change-induced sea-level rise (SLR) due to their low altitude and the great attractiveness of the region for tourism. This attractiveness has resulted in a very significant development of second homes, which represent half of the housing stock and three quarters of the total capacity for tourism hospitality. In the context of climate change adaptation measures related to SLR, it is imperative to consider the perceptions of second-home owners and their place in local governance arrangements. Scientists advocate the implementation of managed retreat policies to reduce vulnerability by reducing the exposure of buildings, but both the social acceptability and the economic feasibility of these policies are very low. We assume that second-home owners have different perceptions of the risk of inundation and are less involved in the governance mechanisms. It is very difficult to mobilise a large number of own...

Electrical characterizations of silver chalcogenide glasses

Abstract: We present a study of the electrical properties of silver chalcogenide glasses ‘40AgI’–30Ag2S–30GeS2, 45AgI–27.5Ag2S–27.5GeS2 and 50AgI–25Ag2S–25GeS2 in the 77–400 K temperature and the 20 Hz to 1 MHz frequency ranges. In our temperature range, a large variation of the real permittivity is observed, in relation with an electrodes polarization effect. As the amount of silver iodide increases in the Ag2S–GeS2 matrix, the glass transition temperature and the activation energies decrease, the electrical conductivity increases and reaches 4 Ω−1 m−1 at room temperature for the glass with 50% AgI. The study of the conductivity shows a behavior due to a high ionic conductivity, thermally activated with Edc = 0.21 eV, E1 = 0.075 eV (40AgI–30Ag2S–30GeS2, 45AgI–27.5Ag2S–27.5GeS2), Edc = 0.17 eV, E1 = 0.055 eV for 50AgI–25Ag2S–25GeS2. For these glasses, we have seen three conductivity regimes. The first two terms are thermally activated. The third term cannot be actually clearly identified because either it is thermally activated with a very low activation energy and frequency dependent, or it is almost non-thermally activated and frequency dependent.