Photoemission Spectra from Reduced Density Matrices: the Band Gap in Strongly Correlated Systems

We present a method for the calculation of photoemission spectra in terms of reduced density matrices. We start from the spectral representation of the one-body Green's function G, whose imaginary part is related to photoemission spectra, and we introduce a frequency-dependent effective energy that accounts for all the poles of G. Simple approximations to this effective energy give accurate spectra in model systems in the weak as well as strong correlation regime. In real systems reduced density matrices can be obtained from reduced density-matrix functional theory. Here we use this approach to calculate the photoemission spectrum of bulk NiO: our method yields a qualitatively correct picture both in the antiferromagnetic and paramagnetic phases, contrary to mean-field methods, in which the paramagnet is a metal

Classe de Ciências

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Mielopatía compresiva por occipitalización del atlas

Se presenta un caso clínico de occipitalización del atlas, alteración congénita caracterizada por la existencia de una fusión parcial o total del anillo óseo del atlas con la base del occipucio. En el 50% de los casos se asocia una impresión basilar que origina síntomas neuroló- gicos por compresión neural si la odontoides sobrepasa la abertura del foramen magnun. Es importante el determinar la existencia de esta anomalía, incluso ante síntomas comunes como dolor cervical y vértigo. La cirugía es la terapéutica de elección, principalmente cuando existe inestabilidad atloaxoidea, y consiste en la estabilización articular mediante fusión posterior cervical suboccipital asociada en casos de grave compromiso neurológico de resección transoral de la odontoides. En nuestro caso el paciente fue sometido a tratamiento conservador al rechazar voluntariamente la intervención.A case of occipitalization of the atlas is reported. It is a congenital abnormality of the cervical spine characterized by partial or total fusion of the atlas with the occipital. In 50% of cases this lesions are associated with basilar impression and neurological symptoms determine. It is important to if this anomaly is present even in the presence of common symptoms like cervical pain and vertigo. Surgery is the treatment of choice if the inestability exist consistingin posterior occipital-axis arthrodesis with transoral resection of the odontoid process if severe neurological symptoms are present

Crystallographic orientation inhomogeneity and crystal splitting in biogenic calcite

The calcitic prismatic units forming the outer shell of the bivalve Pinctada margaritifera have been analysed using scanning electron microscopy–electron back-scatter diffraction, transmission electron microscopy and atomic force microscopy. In the initial stages of growth, the individual prismatic units are single crystals. Their crystalline orientation is not consistent but rather changes gradually during growth. The gradients in crystallographic orientation occur mainly in a direction parallel to the long axis of the prism, i.e. perpendicular to the shell surface and do not show preferential tilting along any of the calcite lattice axes. At a certain growth stage, gradients begin to spread and diverge, implying that the prismatic units split into several crystalline domains. In this way, a branched crystal, in which the ends of the branches are independent crystalline domains, is formed. At the nanometre scale, the material is composed of slightly misoriented domains, which are separated by planes approximately perpendicular to the c-axis. Orientational gradients and splitting processes are described in biocrystals for the first time and are undoubtedly related to the high content of intracrystalline organic molecules, although the way in which these act to induce the observed crystalline patterns is a matter of future research

Stochastic evaluation of sewer inlet capacity on urban pluvial flooding

In this paper we present an innovative methodology to stochastically assess the impact of sewer inlet conditions on urban pluvial flooding. The results showed that sewer inlet capacity can have a large impact on the occurrence of urban pluvial flooding. The methodology is a useful tool for dealing with uncertainties in sewer inlet operational conditions and contribute to comprehensive assessment of urban pluvial risk assessment

Síndrome uña-rótula

Presentamos el estudio de 3 casos afectos de un síndrome "uña-rótula", con historia familiar positiva en uno de ellos. Este síndrome es un transtorno hereditario de transmisión autosómica dominante, caracterizado por displasia ungueal y de articulacione s y formación de una s excrecencia s óseas características a nive l del ilíaco (cuernos ilíacos). El síndrome completo se define por los cambios esqueléticos asociados a una nefropatía. Describimos las anomalías clínico-radiográficas de tres paciente s y realizamos una revisión de la literatura sobre esta displasia poco frecuente.The author s showed thre e patients affected by "nail patella" syndrome with positive familiar history in one case. The "nail patella" syndrome is an autosomal dominant condition, characterized by nail and joint dysplasia and extra bone formation at the os ilium. The complet e syndrome is characterized by a serie s of skeletal disorders and specific nephropathy. This article reports the clinical and roentgenographi c findings of three patients and the results of the study of their families. A review of the literature is done

UV polymerization of room temperature ionic liquids for high temperature PEMs: Study of ionic moieties and crosslinking effects

The conductivity performance of commercial available room-temperature ionic liquids (RTILs) has been evaluated from room conditions up to 200oC as a function of relative humidity for their potential application in high temperature PEMs. In particular, ammonium and imidazolium based ionic liquids with different counterions and substituents have been investigated. On the basis of conductivity performance, the best RTILs have been selected for the preparation of all solid state ion conductive films by bulk photo-assisted radical polymerization. The goodness of the UV photopolymerization of the respective monomeric ionic liquids (MILs) with vinyl functionality as a function of divynilbenzene cross-linker content has been evaluated by TGA and FTIR analyses. Poly-ionic liquid (PIL) films have been successfully accomplished for polymerized H-3-vinylimidazolium bis(trifluoromethanesulfonyl)imide upon exposure to 365 nm UV lamp with an intensity of 2.4 mW/cm2 for 15 min. Conductivity values above 1.1 S∙cm-1 at 200oC have been registered for pure poly[1-(3H-imidazolium)ethylene] bis(trifluoromethanesulfonyl)imide