Disorder induced metallicity in amorphous graphene

We predict a transition to metallicity when a sufficient amount of disorder is induced in graphene. Calculations were performed by means of a first principles stochastic quench method. The resulting amorphous graphene can be seen as nanopatches of graphene that are connected by a network of disordered small and large carbon rings. The buckling is minimal and we believe that it is a result of averaging of counteracting random in-plane stress forces. The linear response conductance is obtained by a model theory as function of lattice distortions. Such metallic behaviour is a much desired property for functionalisation of graphene to realize a transparent conductor, e.g. suitable for touch-screen devices

Formulación de modelos pronósticos de Z-Score talla/edad y hemoglobinemia en niños expuestos a plomo. La Oroya antigua, Perú

Publicación a texto completo no autorizada por el autorFormula modelos pronóstico de z score T/E y de hemoglobinemia (Hb) en niños y nuñas de 06 59 meses de edad expuestos a plomo en La Oroya Antigua (Junín-Perú). Estudio de diseño analítico, transversal, prospectivo. Se seleccionó 98 niños mediante muestreo aleatorio sistemático y luego se post-estratificó en grupos etarios (06 a 23, 24 a 47 y 48 a 59 meses) considerando la velocidad de crecimiento y la concentración de plomo en sangre (PbS). Se realizó la evaluación antropométrica y la determinación de hemoglobina y plomo en sangre. Se aplicó una encuesta socioeconómica a las madres de los niños y niñas, además de tres recordatorios de 24 horas. Se realizó dos análisis de regresión lineal múltiple por cada grupo etario, considerándose como variables dependientes: z-score T/E y Hemoglobinemia (HbS), y como independientes: PbS, adecuación de consumo de nutrientes, indicador socioeconómico y capacidad de cuidado de la madre. Se empleó el software STATA v.11.1 y SPSS v.19. Modelos pronóstico de z-score T/E y Hemoglobinemia por grupo etario. Primer grupo, z-score T/E=-3.518 –0.017*PbS + 0.657*Proteínas de Origen Animal (POA) + 0.527*Calcio + 0.769*Zinc (R2:0.7384); HbS=9.622 – 0.021*PbS + 2.301*Hierro Hem + 0.899*Vitamina A – 0.029*Interacción PbS-Vitamina A (R2:0.7086). Segundo grupo, z-score T/E= -2.854 – 0.028*PbS + 0.512*POA + 0.791*Zinc + 0.373*Vitamina A (R2=0.6443); HbS=10.6 – 0.021*PbS + 2.401*Hierro Hem + 0.285*Vitamina A (R2:0.5173). Tercer grupo, z-score T/E =-1.799 – 0.059*PbS+ 0.721*POA + 0.384*Vitamina A + 0.116*Vitamina C (R2:0.7016); HbS =10.597 – 0.018*PbS + 2.524*Hierro Hem + 0.616*Vitamina A (R2:0.5514). El aporte de proteínas de origen animal resulta ser una variable predictora favorable en el modelo del z-score T/E en los tres grupos etarios; mientras que el aporte de hierro hem y la adecuación de consumo de vitamina A lo son en el modelo de hemoglobinemia. Por el contrario, la concentración de plomo en sangre constituye una variable predictora desfavorable tanto en el modelo de z-score T/E para el tercer grupo etario como en el modelo de hemoglobinemia para el primer grupo etario.Tesi

Liquid state properties from first principles DFT calculations: Static properties

In order to test the Vibration-Transit (V-T) theory of liquid dynamics, ab initio density functional theory (DFT) calculations of thermodynamic properties of Na and Cu are performed and compared with experimental data. The calculations are done for the crystal at T = 0 and T_m, and for the liquid at T_m. The key theoretical quantities for crystal and liquid are the structural potential and the dynamical matrix, both as function of volume. The theoretical equations are presented, as well as details of the DFT computations. The properties compared with experiment are the equilibrium volume, the isothermal bulk modulus, the internal energy and the entropy. The agreement of theory with experiment is uniformly good. Our primary conclusion is that the application of DFT to V-T theory is feasible, and the resulting liquid calculations achieve the same level of accuracy as does ab initio lattice dynamics for crystals. Moreover, given the well established reliability of DFT, the present results provide a significant confirmation of V-T theory itself.Comment: 9 pages, 3 figures, 5 tables, edited to more closely match published versio

FACTORES DE RIESGO QUE INCIDEN EN LA RETINOPATÍA DEL PREMATURO EN EL SERVICIO DE NEONATOLOGÍA EN UN HOSPITAL DEL MINISTERIO DE SALUD

Este estudio tiene como objetivo: Determinar los Factores de Riesgo que Inciden en la Retinopatía del Prematuro en el Servicio de Neonatología del Hospital Regional Docente las Mercedes - Chiclayo 2014, es de tipo cuantitativo, diseño no experimental, descriptivo y retrospectivo, la población muestral fue de 136 recién nacidos prematuros según criterios de inclusión y exclusión. Las técnicas de recolección de datos son de análisis documental y bibliográfico, teniendo como fuentes primarias las historias clínicas para lo cual se utilizó una ficha de recolección de datos validado por 3 expertos en el área de neonatología. Obteniendo como resultados: Factores Maternos: Infecciones del Tracto Urinario con un 44,1%, 28,7% con Preclampsia otras hacen Eclampsia, el 20,6% con Hipertensión Arterial, el 19,9% Anemia y por último 18,4% con Diabetes Mellitus, Factores Neonatales: Apnea (89,7%), Asfixia con 78,7%, 71,3% Sepsis, EMH con 67,6%, y obteniendo así un 57,4% que tuvieron SDR, Factores Predisponen: es el CPAP con un 30,9%, Ventilador Mecánico 22%, Cánula Binasal 19,9%. Puesto que con el análisis realizado con el Chi cuadrado nos da valores p < 0,05 que nos indica que es significativo. Se concluyó que los hallazgos en este estudio confirman que estos Multifactores Maternos y del Recién Nacidos Inciden en la Retinopatía del Prematuro

Non-collinear Magnetism in d- and f-electron Systems

In this thesis, non-collinear magnetism has been studied by using density functional theory and the augmented plane wave method with local orbitals (APW+lo). Two conditions for non-collinear instabilities have been identified in this thesis. First, the Fermi energy should cut through both spin up and down states. Secondly, strong nesting between the spin up and spin down Fermi surfaces is needed. The two criteria described here can be fulfilled by tuning the exchange-splitting and/or by modifying the volume. Calculations on several elements; bcc V, bcc and fcc Mn, bcc Fe, bcc and fcc Co, and bcc and fcc Ni show that a non-collinear state can be stabilized provided that the criteria discussed above are met. More complex materials have also been analyzed in terms of these two criteria. The substitutional alloys TlCo2Se2-xSx are found in experiments to possess spin spiral structures for x = {0-1.5} and at a concentration x = 1.75 the alloys become ferromagnetic. As S takes the place of Se in the crystal structure the distance between the Co layers is reduced and the turn angle of the spin spiral becomes smaller until it totally vanishes at x = 1.75. This thesis show that the evolution of the magnetic structure in these alloys is the consequence of a modification of the distance between Co layers, which induces a change in the interlayer exchange coupling. Fermi surfaces have been analyzed in TbNi5 in order to determine nesting features which would be responsible for the magnetic spin spiral observed in this material. The electronic structure of CeRhIn5 is also reported in this thesis. Furthermore, the 3-k magnetic structure of UO2 was investigated and the crystal field levels were calculated. Transition metal systems such as Fe in the superconducting high-pressure hcp phase and in the fcc crystal structure were also studied. The results obtained for fcc Fe are in accordance with previous reports. However the paramagnetic state in hcp Fe is found to be more stable than the antiferromagnetic configurations discussed earlier in the literature as being favored in the volume range where the hcp phase is stable and superconductivity appears (~ 15 GPa). The complex non-collinear magnetic structure in Mn3IrSi was calculated and the results are found to be in good agreement with experiments

Structural characterization of amorphous YCrO

We perform a theoretical prediction of the structure of amorphous YCrO3. We obtained equivalent amorphous structures by means of two independent first principles density functional theory based methods: molecular dynamics and stochastic quenching. In our structural analysis we include radial and angle distribution functions as well as calculations of bond lengths and average coordination numbers. We find Cr+3 atoms situated in slightly distorted oxygen octahedra throughout the amorphous structures and that the distribution of these octahedra is disordered. The presence of the same Cr+3 local environments that give rise to ferroelectricity in the orthorhombic perovskite structure suggests that the amorphous phase of YCrO3 may also exhibit ferroelectric properties

Conocimientos y estigmas sobre salud mental en familiares de pacientes que acuden a consultorio externo del "Hospital Nacional Cayetano Heredia"

Objectives: To describe knowledge and prejudices about mental health and to determine if there is any association between demographic characteristics, health knowledge and prejudices on mental health. Materials and Method: This is a cross-sectional descriptive study. Three vignettes describing typical cases of depression, panic disorder, and schizophrenia were elaborated, and questions were asked about them. Vignettes and their questions were validated by a group of experts. Each vignette and its questions were administered to 151 relatives of persons attending the outpatient clinic for conditions other than psychiatric disorders, so 453 individual vignettes were assessed. Results: For cases of panic disorder, interviewees preferred patients should be seen by a specialized non-psychiatrist physician (76,0%), and they also considered these patients might die because of an undiagnosed physical condition (57,3%). For cases of depression and schizophrenia, professionals chosen as the most adequate for managing these patients were psychologists (41,7% and 45,0%, respectively). For cases of schizophrenia, an association was found between going to the psychiatrist or having a mental disorder, and they also considered these subjects may represent a threat for their peers (p=0,003 and p<0,001, respectively). Conclusions: A high percentage of interviewees would recommend that patients with schizophrenia or depression should be treated by a psychologist. On the other hand, they also considered that patients with panic disorder may have an undiagnosed physical condition and that they should be treated by a non-psychiatrist physician.Objetivos: Describir los conocimientos y estigmas sobre salud mental y evaluar la asociación entre características demográficas, conocimientos de salud y estigmas. Material y Método: Estudio descriptivo transversal. Se redactaron tres viñetas describiendo un caso típico de depresión, trastorno de pánico y esquizofrenia y se formularon preguntas sobre ellas. Las viñetas y sus preguntas se validaron por juicio de expertos. Se aplicó cada viñeta y sus preguntas a 151 familiares de pacientes no psiquiátricos de consulta externa, incluyéndose un total de 453 individuos. Resultados: Para el caso de trastorno de pánico, se prefirió que el paciente sea visto por un médico especialista no psiquiatra (76,0 %) y se consideró que podía morir de una enfermedad física no diagnosticada (57,3 %). Para el caso de depresión y esquizofrenia el profesional considerado como el más indicado para tratarlo fue el psicólogo (41,7 % y 45,0 %, respectivamente). Para el caso de esquizofrenia, se encontró asociación entre ir al psiquiatra o presentar una enfermedad mental y considerarlo una amenaza para los demás (p=0,003 y p.<.0,001, respectivamente). Conclusiones: Un alto porcentaje recomendaría que pacientes con sintomatología de esquizofrenia o depresión sean tratados por un psicólogo. Por otro lado, se considera con frecuencia, que pacientes con trastorno de pánico tienen una enfermedad física que no ha podido ser diagnosticada y deben ser tratados por un médico no psiquiatra

Nutrient fluxes in a semi-arid microtidal mangrove wetland in the Gulf of California

9 pages, 6 figures, 3 tablesNutrient (C, N and P) fluxes were monitored in a microtidal semi-arid mangrove system, which links a semi-enclosed shallow coastal lagoon with the Gulf of California. We assessed the role of the mangrove ecosystem as a nutrient sink/source and determined how mangrove litterfall rates, tidal regime and climate factors influence these fluxes. Despite high seasonal differences in DOC, POC, N-NO3 and TP levels, nutrient concentrations were only marginally influenced by either hydrological variables or the concentration of these fractions in the adjacent lagoon. The carbon budget appeared to be balanced throughout the study. Retention rates in the mangrove system were related to litterfall rates. Export of DIN was observed mainly in the wet season due to the low nitrogen assimilation efficiency of the system. Import of organic nitrogen was related to the high retention efficiency of particulate organic nitrogen. Phosphorus fractions were imported and retained in the mangrove supporting previous findings that mangroves are phosphorus sinks. Finally, through a simple meta-analysis we tested the quantitative importance of main variables (tidal flow, tidal elevation, tidal range, rainfall, mangrove catchment area, litterfall) controlling mangrove nutrient dynamics. Although results suggest that generalizations can be made about factors regulating nutrient export from mangroves, the lack of statistical significance highlights the relative importance of the local environment for the magnitude of nutrient exchange in mangroves. Future research should focus on finding mechanistic models to explain these general patterns, taking into account the main biogeochemical processes and their roles in coastal ecosystem ecology.This research was supported by the Mexican Secretary of Natural Resources and Environment (SEMARNAT-CONACYT; contract SEMARNAT-2002-C01-0147).Peer reviewe