442 research outputs found

    Election campaign audiences and urban security: Citizens and elections promises during a mediatized political campaign (Argentina 2015)

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    This article analyses the relations between citizens and the electoral campaign regarding insecurity/lack of public safety during the presidential election of 2015. Crime was one of the major concerns of the country that year, so much so that four of the six candidates produced specific election advertising spots on the subject. Within this context, the article asks: What does insecurity mean for citizens? Do they support the promises of the campaign? How do they interpret audio-visual materials about insecurity? The aim is to explore how those viewers interpreted campaign publicity on insecurity/crime during the presidential election of 2015 and to reflect on their role in the processes of political mediatization. Analyzing six focal groups, we were able to conclude that: i. People experience worry about crime in the city and distrust not only the police but the legal system and political representatives; ii. They do not criticize the candidates’ promises, but they can unveil the true or false intentions of election advertising; iii. They distinguish between election advertising aimed at an emotional response (false) and those more logical or rational (closer to the truth).Este artículo analiza la relación entre la ciudadanía con la publicidad electoral sobre inseguridad en la elección presidencial de Argentina en 2015. Durante este año, el crimen urbano fue una de las mayores preocupaciones del país al punto de que cuatro de los seis candidatos presidenciales produjeron spots específicos sobre el tópico. En este contexto, el artículo se pregunta: ¿Qué implicaba la inseguridad para los ciudadanos?, ¿acordaban con las promesas de campaña?, ¿cómo interpretaron los materiales audiovisuales sobre inseguridad? El objetivo es explorar cómo las denominadas audiencias electorales interpretaron las publicidades sobre inseguridad en la elección presidencial de 2015 y reflexionar sobre sobre su lugar en los procesos de mediatización política. La realización de seis grupos focales permitió concluir que las audiencias electorales: i. vivencian con preocupación la inseguridad en la ciudad, desconfían de la justicia, la policía y de sus representantes políticos; ii. no critican las promesas puntuales de los candidatos, sino que procuran develar las intenciones reales o engañosas de las publicidades electorales; iii. definen los fragmentos de publicidad electoral como construidos en clave emotiva (por tanto, falsos), o como lógicos y racionales (por tanto, cercanos a la verdad).

    Theoretical inspection of the spin-crossover [Fe(tzpy)2(NCS)2] complex on Au(100) surface

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    We explore the deposition of the spin-crossover [Fe(tzpy)2(NCS)2] complex on the Au(100) surface by means of density functional theory (DFT) based calculations. Two different routes have been employed: low-cost finite cluster-based calculations, where both the Fe complex and the surface are maintained fixed while the molecule approaches the surface; and periodic DFT plane-wave calculations, where the surface is represented by a four-layer slab and both the molecule and surface are relaxed. Our results show that the bridge adsorption site is preferred over the on-top and fourfold hollow ones for both spin states, although they are energetically close. The LS molecule is stabilized by the surface, and the HS-LS energy difference is enhanced by about 15%-25% once deposited. The different Fe ligand field for LS and HS molecules manifests on the composition and energy of the low-lying bands. Our simulated STM images indicate that it is possible to distinguish the spin state of the deposited molecules by tuning the bias voltage of the STM tip. Finally, it should be noted that the use of a reduced size cluster to simulate the Au(100) surface proves to be a low-cost and reliable strategy, providing results in good agreement with those resulting from state-of-the-art periodic calculations for this system.Ministerio de Ciencia e Innovación PGC2018- 101689-B-I0

    Ab initio evaluation of the charge-ordering in α′NaV2O5\alpha^\prime NaV_2O_5

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    We report {\it ab initio} calculations of the charge ordering in α′NaV2O5\alpha^\prime NaV_2O_5 using large configurations interaction methods on embedded fragments. Our major result is that the 2py2p_y electrons of the bridging oxygen of the rungs present a very strong magnetic character and should thus be explicitly considered in any relevant effective model. The most striking consequence of this result is that the spin and charge ordering differ substantially, as differ the experimental results depending on whether they are sensitive to the spin or charge density.Comment: 4 page

    A convenient decontraction procedure of internally contracted state-specific multireference algorithms

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    Internally contracted state-specific multireference MR algorithms, either perturbative such as CASPT2 or NEVPT2, or nonperturbative such as contracted MR configuration interaction or MR coupled cluster, are computationally efficient but they may suffer from the internal contraction of the wave function in the reference space. The use of a low dimensional multistate model space only offers limited flexibility and is not always practicable. The present paper suggests a convenient state-specific procedure to decontract the reference part of the wave function from a series of state-specific calculations using slightly perturbed zero-order wave functions. The method provides an orthogonal valence bond reading of the ground state and an effective valence Hamiltonian, the excited roots of which are shown to be relevant. The orthogonal valence bond functions can be considered quasidiabatic states and the effective valence Hamiltonian gives therefore the quasidiabatic energies and the electronic coupling among the quasidiabatic states. The efficiency of the method is illustrated in two case problems where the dynamical correlation plays a crucial role, namely, the LiF neutral/ionic avoided crossing and the F2 ground state wave functio

    Proposal of an extended t-J Hamiltonian for high-Tc cuprates from ab initio calculations on embedded clusters

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    A series of accurate ab initio calculations on Cu_pO-q finite clusters, properly embedded on the Madelung potential of the infinite lattice, have been performed in order to determine the local effective interactions in the CuO_2 planes of La_{2-x}Sr_xCuO_4 compounds. The values of the first-neighbor interactions, magnetic coupling (J_{NN}=125 meV) and hopping integral (t_{NN}=-555 meV), have been confirmed. Important additional effects are evidenced, concerning essentially the second-neighbor hopping integral t_{NNN}=+110meV, the displacement of a singlet toward an adjacent colinear hole, h_{SD}^{abc}=-80 meV, a non-negligible hole-hole repulsion V_{NN}-V_{NNN}=0.8 eV and a strong anisotropic effect of the presence of an adjacent hole on the values of the first-neighbor interactions. The dependence of J_{NN} and t_{NN} on the position of neighbor hole(s) has been rationalized from the two-band model and checked from a series of additional ab initio calculations. An extended t-J model Hamiltonian has been proposed on the basis of these results. It is argued that the here-proposed three-body effects may play a role in the charge/spin separation observed in these compounds, that is, in the formation and dynamic of stripes.Comment: 24 pages, 4 figures, submitted to Phys. Rev.

    Amplified Spontaneous Emission Properties of Semiconducting Organic Materials

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    This paper aims to review the recent advances achieved in the field of organic solid-state lasers with respect to the usage of semiconducting organic molecules and oligomers in the form of thin films as active laser media. We mainly focus on the work performed in the last few years by our research group. The amplified spontaneous emission (ASE) properties, by optical pump, of various types of molecules doped into polystyrene films in waveguide configuration, are described. The various systems investigated include N,N′-bis(3-methylphenyl)-N,N′-diphenylbenzidine (TPD), several perilenediimide derivatives (PDIs), as well as two oligo-phenylenevinylene derivatives. The ASE characteristics, i.e., threshold, emission wavelength, linewidth, and photostability are compared with that of other molecular materials investigated in the literature

    Censo de focos de "Heterobasidion annosum" (Fr.) Bref. en ecosistemas de pinsapo

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    Se exponen los resultados de un censo de focos de podredumbre radical causada por Heterobasidion annosum (Fr.) Bref. en ecosistemas de Abies pinsapo Boiss. en las tres áreas de distribución natural de la especie en la Península Ibérica: los pinsapares de Sierra de las Nieves (Málaga), Sierra de Grazalema (Cádiz) y Los Reales de Sierra Bermeja (Málaga). La búsqueda del patógeno se dirigió a la observación de los sistemas radicales de los pies derribados visibles en el monte, para posterior delimitación de las zonas afectadas y cumplimentación de una ficha de campo específica para la descripción y caracterización de la enfermedad. El patógeno fue detectado en la totalidad de las áreas muestreadas, en un total de 81 centros de infección o focos, contabilizándose, adicionalmente, 11 zonas de elevada mortandad de pinsapo (áreas de posible infección), donde no pudo comprobarse la presencia del patógeno, si bien ésta se consideró posible. El Parque Natural Sierra de las Nieves fue el más afectado, con un 88.9% de los focos detectados. En Sierra de Grazalema la incidencia fue considerablemente inferior, si bien las características del pinsapar y las particularidades de la enfermedad en la zona hicieron temer de un riesgo generalizado de infección. Finalmente, Los Reales fue la zona menos afectada, con tan sólo un foco con causa atribuible a H. annosum.We expose the results of an inventory of gaps of trees of Abies pinsapo with root decay caused by Heterobasidion annosum. The sampling was developed in ecosystems with Abies pinsapo Boiss., in the species natural areas of the Iberian Peninsula: Sierra de las Nieves (Málaga, Spain), Sierra de Grazalema (Cádiz, Spain) and Los Reales de Sierra Bermeja (Málaga, Spain). The pathogen research was restricted to the observation of the radical systems in windthrown trees, identification in roots and further delimitation of the affected surface. The pathogen was identified in 81 infection centers, aditionally accounting 11 areas of high mortality oí Abies pinsapo trees {areas of possible infection), where the presence of H. annosum was not certain but considered possible. Sierra de las Nieves Natural Park was the most affected area, reaching the 88.9% of the total amount of infections centers. Sierra de Grazalema showed a lower incidence, although the stand features and disease particularities in this Park make us suspect a general and high risk of infection all over the A. pinsapo forest. Finally, Los Reales was the least affected zone, with only one infection center with root decay caused by H. annosum

    Sr_14Cu_24O_41Sr\_{14}Cu\_{24}O\_{41} : a complete model for the chain sub-system

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    A second neighbor t−J+Vt-J+V model for the chain subsystem of the Sr_14Cu_24O_41Sr\_{14}Cu\_{24}O\_{41} has been extracted from ab-initio calculations. This model does not use periodic approximation but describes the entire chain through the use of the four-dimensional crystallographic description. Second neighbors interactions are found to be of same order than the first neighbors ones. The computed values of the second neighbors magnetic interaction are coherent with experimental estimations of the intra-dimer magnetic interactions, even if slightly smaller. The reasons of this underestimation are detailed. The computed model allowed us to understand the origin of the chain dimerisation and predicts correctly the relative occurrence of dimers and free spins. The orbitals respectively supporting the magnetic electrons and the holes have been found to be essentially supported by the copper 3d orbitals (spins) and the surrounding oxygen 2p2p orbitals (holes), thus giving a strong footing to the existence of Zhang-Rice singlets
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