Symmetry considerations in the empirical k.p Hamiltonian for the study of intermediate band solar cells

With the purpose of assessing the absorption coefficients of quantum dot solar cells, symmetry considerations are introduced into a Hamiltonian whose eigenvalues are empirical. In this way, the proper transformation from the Hamiltonian's diagonalized form to the form that relates it with Γ-point exact solutions through k.p envelope functions is built accounting for symmetry. Forbidden transitions are thus determined reducing the calculation burden and permitting a thoughtful discussion of the possible options for this transformation. The agreement of this model with the measured external quantum efficiency of a prototype solar cell is found to be excellent

A propòsit d'un centenari

Hem acomplert cent anys d'existència de la Psicologia social i, en aquests temps, hem estructurat una disciplina científica amb un ample cos conceptual i amb diverses branques o subespecialitats enriquidores. No obstant, el més rellevant es haver arribat a fer de la Psicologia social una eina útil en l'aconseguiment de benestar i de qualitat de vida als diferents àmbits d'intervenció psicològica 'laboral, familiar, comunitari, etc..

Application of photoluminescence and electroluminescence techniques to the characterization of intermediate band solar cells

The intermediatebandsolarcell (IBSC) is a photovoltaic device with a theoretical conversion efficiency limit of 63.2%. In recent years many attempts have been made to fabricate an intermediateband material which behaves as the theory states. One characteristic feature of an IBSC is its luminescence spectrum. In this work the temperature dependence of the photoluminescence (PL) and electroluminescence (EL) spectra of InAs/GaAs QD-IBSCs together with their reference cell have been studied. It is shown that EL measurements provide more reliable information about the behaviour of the IB material inside the IBSC structure than PL measurements. At low temperatures, the EL spectra are consistent with the quasi-Fermi level splits described by the IBSC model, whereas at room temperature they are not. This result is in agreement with previously reported analysis of the quantum efficiency of the solarcell

New invariants for entangled states

We propose new algebraic invariants that distinguish and classify entangled states. Considering qubits as well as higher spin systems, we obtained complete entanglement classifications for cases that were either unsolved or only conjectured in the literature.Comment: published versio

La mediació en l'àmbit laboral

El present capítol té per objecte l'anàlisi de l'estat actual de la mediació laboral a Catalunya. En primer lloc, l'estudi es centra en l'anàlisi dels diferents mecanismes de conciliació i/o mediació creats i regulats per, d'una banda, el legislador i, per l'altra, la negociació col·lectiva. En segon lloc, s'exposen els resultats obtinguts de dos estudis quantitatius realitzats en matèria de mediació. En el primer estudi realitzat s'analitza el paper del Tribunal Laboral de Catalunya i del Departament de Treball com a organismes encarregats de mediar en conflictes laborals. Concretament, s'analitza la participació i efectivitat d'aquests dos organismes en la mediació de conflictes laborals efectuats a Catalunya el 2009, així com les característiques dels conflictes laborals que es presenten davant d'aquests organismes (dimensions, matèria del conflicte, dimensions de les empreses afectades, sectors econòmics implicats, territorialitat, etc.). En el segon estudi quantitatiu realitzat s'analitza el coneixement, ús i avantatges de la mediació laboral interna en el sí de les empreses catalanes per a la resolució de conflictes laborals. En tercer lloc, es presenten els resultats dels dos estudis qualitatius realitzats a, per un banda, persones del departament de Recursos Humans o d'Assessoria Jurídica d'empreses i sindicats de Catalunya que han acudit als serveis de mediació del TLC durant el mes de gener del 2010 i, per altra banda, a mediadors i mediadores professionals en exercici en el Departament de Treball i el Tribunal Laboral de Catalunya. En quart i darrer lloc, s'exposen les conclusions de l'estudi. Les conclusions, dividides en tres apartats, fan referència a les característiques de la mediació laboral a Catalunya, el perfil de la persona mediadora i inclouen un seguit de recomanacions encaminades a incentivar i generalitzar l'ús de la mediació com a instrument de resolució conflictes laborals i millorar aquesta instituci

Water management in the Iberian península: new solutions for old problems?

9 pages, 4 figures, 2 tables, 12 references.-- XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on CLIMWATER 2010: Horticultural Use of Water in a Changing Climate.-- Lisboa, Portugal.The increasing demand of fresh water from different sectors puts pressure in scientists and engineers to develop more effective ways of using the available water resources. In Spain and Portugal, countries of Mediterranean climate with hot and dry summers, the allocation of water resources is especially controversial. This emphasises the need for a rational use of water. We present features and recent developments of Spanish and Portuguese water policies and some consequences on the use of land and water. We consider how social, economic and environmental problems might evolve in the expected scenarios of population growth and climatic change, and analyse the response from the scientific community to the new challenges. Finally, we pointed out that the combined efforts of professionals and users provide useful tools for satisfying the consumers demand at the same time that the environmental foot¬print is minimized.Peer Reviewe

U/Th dating of Quaternary travertines at the middle River Llobregat (NE Iberian Peninsula, Nortwestern Mediterranean). Correlation with sea-level changes

The dating of the fluvial terraces of the middle River Llobregat enabled one to establish a correlation between the sedimentation episodes in continental zones and in neighbouring deltaic and coastal areas in the NE Iberian continental margin. The fluvial Terraces 4 (+85-95 m above river level) and 3 (+55-65 m above river level) are made up by or include travertines, which were deposited around 350,000 and 111,000 years ago, respectively. These radiometric ages correspond to two high sea level periods: the Eemian interglacial (isotopic stage 5e) and the interglacial related to isotopic stage 9. However, other travertine units in the valley, such as the Can Tobella staggered cascade travertines, were formed during the Holocene, probably due to hydrothermal spring activity related to the tectonic contact between the Catalan Coastal Ranges and the Ebro Basin