Frenkel Excitons in Vacancy-Ordered Titanium Halide Perovskites (Cs₂TiX₆)

Low-cost, nontoxic, and earth-abundant photovoltaic materials are long-sought targets in the solar cell research community. Perovskite-inspired materials have emerged as promising candidates for this goal, with researchers employing materials design strategies including structural, dimensional, and compositional transformations to avoid the use of rare and toxic elemental constituents, while attempting to maintain high optoelectronic performance. These strategies have recently been invoked to propose Ti-based vacancy-ordered halide perovskites (A2TiX6; A = CH3NH3, Cs, Rb, or K; X = I, Br, or Cl) for photovoltaic operation, following the initial promise of Cs2SnX6 compounds. Theoretical investigations of these materials, however, consistently overestimate their band gaps, a fundamental property for photovoltaic applications. Here, we reveal strong excitonic effects as the origin of this discrepancy between theory and experiment, a consequence of both low structural dimensionality and band localization. These findings have vital implications for the optoelectronic application of these compounds while also highlighting the importance of frontier-orbital character for chemical substitution in materials design strategies

L2 learners' knowledge of verb form-function relationships at different stages in the acquisition of English as a second language : a study of college learners' interlanguage in Zaire.

Available from British Library Document Supply Centre- DSC:D97832 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Gender wage discrimination in the Turkish labor market

URL des Documents de travail :http://ces.univ-paris1.fr/cesdp/CESFramDP2007.htmDocuments de travail du Centre d'Economie de la Sorbonne 2007.67 - ISSN : 1955-611XWhile the topic of gender equality turns out to be an important element in the preparation of Turkey to join the European Union, very little empirical research on this issue has been done using Turkish data. This paper aims to contribute toward filling this gap. We propose an estimate of the wage discrimination in Turkey relying on different decompositions of the gender waga differential. The data set used is the 2003 Turkish Household Budget Survey. In Turkey, the observed average gender wage gap is about 25,2 % in favor of men for the salaried population and around 60 % of it may be attributed to discrimination. In terms of gender wage discrimination, with an observed wage gap close to those observed in France and Italy, and a discrimination component close to the ones obtained in Spain and Greece with comparable methods, Turkey happens to do not so bad. But, in the Turkish case, wage discrimination appears to be a bad indicator of gender inequalities in the labor market, as exclusion and segregation of women are the main concerns.Si le thème de l'égalité des sexes se révèle être un sujet sensible dans les discussions préparatoires à une future adhésion de la Turquie à l'Union Européenne, peu de travaux empiriques ont été menés sur données turques. Cet article propose une estimation de la discrimination salariale sur le marché du travail turc à partir de différentes décompositions de l'écart de salaires hommes-femmes, sur la base de l'Enquête ménage 2003. Il apparaît, qu'en moyenne, en Turquie, sur la population salariée, un homme touche 25,2 % de plus qu'une femme, et qu'environ 60 % de cet écart peut être attribué à des pratiques discriminatoires. Du point de vue de la discrimination salariale, avec un écart de salaires observé du même ordre que ceux constatés en France et en Italie, et une part attribuée à la discrimination, à partir de méthodes directement comparables, proche de celles obtenues sur l'Espagne et la Grèce, la Turquie se situe dans les standards européens. Mais, dans le cas turc, les limites des mesures de discrimination salariale comme indicateur des inégalités hommes-femmes sur le marché du travail apparaissent clairement, l'exclusion et la ségrégation étant les problèmes majeurs auxquels sont confrontées les femmes

Proceedings of the second "international Traveling Workshop on Interactions between Sparse models and Technology" (iTWIST'14)

The implicit objective of the biennial "international - Traveling Workshop on Interactions between Sparse models and Technology" (iTWIST) is to foster collaboration between international scientific teams by disseminating ideas through both specific oral/poster presentations and free discussions. For its second edition, the iTWIST workshop took place in the medieval and picturesque town of Namur in Belgium, from Wednesday August 27th till Friday August 29th, 2014. The workshop was conveniently located in "The Arsenal" building within walking distance of both hotels and town center. iTWIST'14 has gathered about 70 international participants and has featured 9 invited talks, 10 oral presentations, and 14 posters on the following themes, all related to the theory, application and generalization of the "sparsity paradigm": Sparsity-driven data sensing and processing; Union of low dimensional subspaces; Beyond linear and convex inverse problem; Matrix/manifold/graph sensing/processing; Blind inverse problems and dictionary learning; Sparsity and computational neuroscience; Information theory, geometry and randomness; Complexity/accuracy tradeoffs in numerical methods; Sparsity? What's next?; Sparse machine learning and inference.Comment: 69 pages, 24 extended abstracts, iTWIST'14 website: http://sites.google.com/site/itwist1