Structure optimization effects on the electronic properties of Bi2_2Sr2_2CaCu2_2O8_8

We present detailed first-principles calculations for the normal state electronic properties of the high T$_C$ superconductor Bi$_2$Sr$_2$CaCu$_2$O$_8$, by means of the linearized augmented plane wave (LAPW) method within the framework of density functional theory (DFT). As a first step, the body centered tetragonal (BCT) cell has been adopted, and optimized regarding its volume, $c/a$ ratio and internal atomic positions by total energy and force minimizations. The full optimization of the BCT cell leads to small but visible changes in the topology of the Fermi surface, rounding the shape of CuO$_2$ barrels, and causing both the BiO bands, responsible for the pockets near the \textit{\=M} 2D symmetry point, to dip below the Fermi level. We have then studied the influence of the distortions in the BiO plane observed in nature by means of a $\sqrt{2}\times\sqrt{2}$ orthorhombic cell (AD-ORTH) with $Bbmb$ space group. Contrary to what has been observed for the Bi-2201 compound, we find that for Bi-2212 the distortion does not sensibly shift the BiO bands which retain their metallic character. As a severe test for the considered structures we present Raman-active phonon frequencies ($q = 0$) and eigenvectors calculated within the frozen-phonon approximation. Focussing on the totally symmetric A$_{g}$ modes, we observe that for a reliable attribution of the peaks observed in Raman experiments, both $c$- and a-axis vibrations must be taken into account, the latter being activated by the in-plane orthorhombic distortion.Comment: 22 pages, 4 figure

ADVANCES IN THE CONTROL OF THRIPS PALMI (KARNY) (THYSANOPTERA : THRIPIDAE) IN PUERTO RICO

The oriental thrips, Thrips palmi, was introduced into Puerto Rico in 1986- 87, causing severe damage on solanaceous and cucurbitaceous crops. In 1988 and 1989, trials were established at the Juana Diaz Experiment Substation to evaluate the efficacy of low and high rates of methomyl (0.5 Kg & 1 Kg ΑΙ/ha), azinphosmethyl (281 & 560 g ΑΙ/ha), esfenvalerate (32 & 57 g ΑΙ/ha) and oxamyl (560 g & 1.1 Kg/ha) in reducing oriental thrips populations. Application intervals, i.e, once ortwice/week, were also studied in a completely randomized block factorial design. Plots were sampled at weekly intervals. No differences in thrips population densities were detected between insecticides nor application rates from neither year. Similarly no differences were found between the effectiveness of high or low insecticide doses. Plant yield was greatly influenced by treatment, with esfenvalerate methomyl unsprayed control azinphosmethyl oxamyl. No correlations were found between yield and thrips population density. Mean thrips population was 0.1 individuals per leaf. ----- Le Thrips oriental, Thrips palmi, a été introduit à Porto Rico en 1986-87, causant des pertes sérieuses sur les cultures de Solanées et de Cucurbitacées. En 1988 et 1989, des études ont été entreprises à la station expérimentale de Juana Diaz pour évaluer l'efficacité de traitement à faibles et fortes doses de méthomyl (0,5 Kg et 1 Kg ΑΙ/ha), d'azinphosméthyl (281 et 560 g ΑΙ/ha), d'esfenvalerate (32 et 57 g ΑΙ/ha) et d'oxamyl (560 et 1,1 Kg/ ha) pour le contrôle des populations de thrips. L'effet de l'intervalle entre plusieurs applications (une ou deux fois par semaine) a également été étudié en utilisant un dispositif en bloc et en randomisation totale. Des échantillonnages hebdomadaires ont été effectués pour cela. La densité de population des thrips n'a pas été influencée par l'insecticide utilisée, ni par les doses ni par les dates de traitement. Par contre, le rendement a beaucoup varié suivant l'insecticide. On peut donner le classement suivant par ordre décroissant d'efficacité : esfenvalérate, méthomyl, témoin, azinphosméthyl, oxamyl. Nous n'avons mis en évidence aucune corrélation entre le rendement et la densité de population de thrips. Les moyennes de population étaient de 0,1 individu par feuille

Gradiente florístico das florestas secundárias do Nordeste Paraense Floristic gradient of the northeast Paraense secondary forests

O presente estudo descreve um gradiente florístico de uma cronosequência de florestas secundárias do Nordeste Paraense, a partir de 19 sítios de diferentes idades, avaliados em diferentes anos. Foram usados os dados de densidade e realizada análise de regressão para riqueza, diversidade, densidade, densidade relativa máxima e equibilidade em relação à idade. Foi usado o método de análise de agrupamento hierárquico, sendo a distância euclidiana utilizada como medida de dissimilaridade e aplicada uma Análise de Componente Principal (PCA) para confirmação dos grupos. Após a definição dos grupos, foi feita a análise indicadora de espécies (IndVal) sobre a mesma matriz utilizada para análise de agrupamento. Encontrou-se um gradiente geográfico na cronosequência analisada e as espécies Tapirira guianensis, Vismia guianensis, Inga alba, Lacistema aggregatum, Croton maturensis, Abarema jupunba, Inga rubiginosa, Guateria poepigiana e Thyrsodium paraense, são indicadoras das florestas secundárias do Nordeste Paraense analisadas neste estudo.<br>This study describes a floristic gradient of secondary forest chronosequence in northeast of Pará State - Brazil, from 19 sites of different ages, evaluated in different years. We used density data and carried out regression analysis for richness, diversity, density, maximum relative density and equitability in relation to the age. We used the hierarchic grouping method of analysis and the Euclidean distance as dissimilarity measure, and applied a Principal Component Analysis (PCA) for confirming the groups. After defining the groups, we made an indicating species analysis (IndVal) on the same matrix used for the grouping analysis. We found a geographic gradient in the chronosequence analyzed and the species Tapirira guianensis, Vismia guianensis, Inga alba, Lacistema aggregatum, Croton maturensis, Abarema jupunba, Inga rubiginosa, Guateria poepigiana and Thyrsodium paraense to be indicators of the northeast Para (Brazil) secondary forests analyzed in this study

Atención integral del neonato con encefalopatía hipóxico-isquémica en España

Introducción Apenas conocemos cómo es la asistencia de los recién nacidos (RN) con encefalopatía hipóxico-isquémica (EHI) en hipotermia terapéutica (HT), especialmente si existen protocolos asistenciales, la neuromonitorización que se realiza o cómo es la aproximación al pronóstico neurológico. Este conocimiento permite detectar e implementar áreas de mejora asistencial. Método Estudio transversal de los 57 hospitales españoles que realizaban HT en 2015, mediante cuestionario sobre: 1) la disponibilidad de protocolos y de recursos tecnológicos; 2) el uso de herramientas de neuromonitorización; 3) los conocimientos de los profesionales; 4) la información pronóstica que se da los padres, y 5) el informe al alta y del plan de seguimiento. Resultados El 95% utiliza enfriamiento corporal-total servocontrolado y dispone de protocolos específicos de actuación. El 70% utiliza sedación y el 68% deja al paciente a dieta absoluta. La monitorización con electroencefalografía integrada por amplitud se utiliza en más del 80% de los centros, aunque solo en el 50% la enfermera es capaz de interpretarlo. La saturación de oxígeno cerebral es escasamente monitorizada (16%). Entre los estudios diagnóstico-pronósticos, la neuroimagen es universal, pero los neurobiomarcadores apenas se utilizan (29%). Solo el 21% ofrece información pronóstica antes de las 72 h de vida; sin presencia de la enfermera en el 70%. El seguimiento lo realiza el neuropediatra (84%), con una duración desigual entre centros. Conclusiones La asistencia del RN con EHI en España es adecuada, con áreas de mejora en: neuromonitorización, sedación, marco temporal de la información pronóstica, trabajo en equipo y estandarización de la duración del seguimiento