2,666 research outputs found

    Comment on "Direct evidence for hidden one-dimensional Fermi surface of hexagonal K0.25WO3"

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    We comment a recent work titled "Direct evidence for hidden one-dimensional Fermi surface of hexagonal K0.25WO3". In this paper the authors report photoemission and theoretical results on the K0.25WO3 system which led them to propose that a Charge Density Wave (CDW), associated with hidden one-dimensional bands, was responsible for the well known resistivity anomaly in such system. In the present comment we report the results of a first principles density functional theory (DFT) study showing that there are no one-dimensional bands as suggested by these authors

    Ab initio two-dimensional multiband low-energy models of EtMe_3Sb[Pd(dmit)_2]_2 and \kappa-(BEDT-TTF)_2Cu(NCS)_2 with comparisons to single-band models

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    We present ab initio two-dimensional extended Hubbard-type multiband models for EtMe_3Sb[Pd(dmit)_2]_2 and \kappa-(BEDT-TTF)_2Cu(NCS)_2, after a downfolding scheme based on the constrained random phase approximation (cRPA) and maximally-localized Wannier orbitals, together with the dimensional downfolding. In the Pd(dmit)_2 salt, the antibonding state of the highest occupied molecular orbital (HOMO) and the bonding/antibonding states of the lowest unoccupied molecular orbital (LUMO) are considered as the orbital degrees of freedom, while, in the \kappa-BEDT-TTF salt, the HOMO-antibonding/bonding states are considered. Accordingly, a three-band model for the Pd(dmit)_2 salt and a two-band model for the \kappa-(BEDT-TTF) salt are derived. We derive single band models for the HOMO-antibonding state for both of the compounds as well.Comment: 10 pages, 9 figures, 3 tables; submitted to Physical Review

    Autoria i creació

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    Clavé i la construcció d'una tradició poètica

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    Sovereignti-e-s

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    Quan el sistema econòmic i polític col·lapsa i la matriu cultural deixa de ser un referent de significat, és un bon moment per recordar algunes màximes dels antics grecs. Pensaments i intuïcions que responien a qüestions ètiques en un context de corrupció, on la paraula no tenia més valor que el de convèncer, on la veritat es confonia amb la raó i on les lleis humanes començaven a definir-se en contraposició a la naturalesa. Sentències com “ocupa’t del tot “o “la mesura és el millor” ens resulten familiars en un moment en què hem d’aprendre novament què és l’essencial i quant és suficient.Cuando el sistema económico y político colapsa y la matriz cultural deja de ser un referente de significado, es un buen momento para recordar algunas máximas de los antiguos griegos. Pensamientos e intuiciones que respondían a cuestiones éticas en un contexto de corrupción, donde la palabra no tenía más valor que el de convencer, donde la verdad se confundía con la razón y donde las leyes humanas empezaban a definirse en contra posición a la naturaleza. Sentencias como “ocúpate del todo” o “la mesura es lo mejor” nos resultan familiares en un momento en que tenemos que aprender nuevamente qué es esencial y cuánto es suficiente.When the political and economic system collapses and the cultural matrix stops being a referent for meaning, it is a good time to remember some maxims of the ancient Greeks. Thoughts and insights that respond to ethical issues in a context of corruption, where words had no more value than the one of convincing, where truth is confused with reason and where human laws began to define their position against nature. Judgments like "take care of the whole" or "moderation is best" are familiar to us in a time when we have to learn again what is essential and how much is enoughPeer Reviewe

    Canopy recovery after drought dieback in holm-oak Mediterranean forests of Catalonia (NE Spain)

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    Climate change is likely to produce more frequent and longer droughts in the Mediterranean region, like that of 1994, which produced important changes in the Quercus ilex forests, with up to 76% of the trees showing complete canopy dieback. At the landscape level, a mosaic of responses to the drought was observed, linked to the distribution of lithological substrates. Damage to the dominant tree species (Q. ilex) and the most common understorey shrub (Erica arborea) was more noticeable on the compact substrates (breccia) than on the fissured ones (schist). This result was consistent with observations documenting deeper root penetration in schist than in breccia materials, allowing the plants growing on fissured substrates to use water from deeper soil levels. Smaller plants were more vulnerable to drought than larger plants in the trees, but not in the shrubs. Overall, Q. ilex was more affected than E. arborea. The resilience of the system was evaluated from the canopy recovery 1 year after the episode. Stump and crown resprouting was fairly extensive, but the damage pattern in relation to substrate, plant size, and species remained similar. The effect of recurrent drought episodes was studied on vegetation patches of Q. ilex located on mountain slopes and surrounded by bare rock. We observed that plants that resprouted weakly after a previous drought in 1985 were more likely to die or to produce poor regeneration in 1995 than plants that had resprouted vigorously. Vegetation patches located on the lower part of the slope were also less damaged than patches situated uphill. The study provides evidence of relevant changes in forest canopy as a consequence of extreme climate events. The distribution of this effect across the landscape is mediated by lithological substrate, causing patchy patterns. The results also support the hypothesis that recurrent droughts can produce a progressive loss of resilience, by depleting the ability of surviving plants to regenerat

    Silvicultura planetària per a la protecció del clima

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    Aplicació gamificada per estalvi energètic en el sector hoteler

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    Creació d'una aplicació mòbil per a l'estalvi energètic en hotels. Per tal de portar a cap aquest estalvi energètic, cal adaptar el consum de recursos de les habitacions al model optim de consum calculat per Necada. Aquesta guia es fara a través de consells que servira l'aplicació.The purpose of this T.F.G., is the creation of a mobile application for energy saving in hotels. In order to carry out this savings, the consumption of resources in the rooms must be adapted to an optimum consumption model calculated by Necada. This guide aims to bring customers to this optimal mod

    Política agraria y propaganda institucional en la década de 1950

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