Deformations of quantum field theories on de Sitter spacetime

Quantum field theories on de Sitter spacetime with global U(1) gauge symmetry are deformed using the joint action of the internal symmetry group and a one-parameter group of boosts. The resulting theory turns out to be wedge-local and non-isomorphic to the initial one for a class of theories, including the free charged Dirac field. The properties of deformed models coming from inclusions of CAR-algebras are studied in detail.Comment: 26 pages, no figure

Transparent metal electrodes from ordered nanosphere arrays

We show that perforated metal electrode arrays, fabricated using nanosphere lithography, provide a viable alternative to conductive metal oxides as transparent electrode materials. The inter-aperture spacing is tuned by varying etching times in an oxygen plasma, and the effect of inter-aperture “wire” thickness on the optical and electronic properties of perforated silver films is shown. Optical transmission is limited by reflection and surface plasmons, and for these results do not exceed 73%. Electrical sheet resistance is shown to be as low as 3 Ω ◻−1 for thermally evaporated silver films. The performance of organic photovoltaic devices comprised of a P3HT:PCBM bulk heterojunction deposited onto perforated metal arrays is shown to be limited by optical transmission, and a simple model is presented to overcome these limitations

The segments method

Se reporta el uso de segmentos como dominio de integración para los métodos libres de mallas de tipo Petrov-Galerkin Local (MLPG). El procedimiento acarrea ventajas en el tratamiento de dominios con forma geométrica irregular, circunda el problema de la precisión numérica en la cuadratura y permite de forma simple traspasar un número arbitrario de derivadas de la función de forma a la función de ponderación. Este trabajo describe el procedimiento algebraico necesario. Además hace referencia al estudio experimental de errores que se hizo para el presente método en casos de prueba bidimensionales; con el objetivo de constatar la estabilidad y precisión del mismo.Peer Reviewe

Numerical modelling with experimental validation applied to the study of stud connectors behaviour in concrete and steel composite structures

In this work, the behaviour of stud shear connectors in composite structures is studied, starting from the via numeric simulation of the push out test in a steel beam – with solid concrete slab concrete section is studied. The study considers material non-linearity material of concrete and steel, adopting firstly a bilinear model for both (steel and concrete), and in the second case, to the difference ofdiffering from other authors, the concrete damage plasticity of the concrete. ABAQUS is used to model the push out test. The basis and methodology of the modelmodelling process push out test are explained. The numerical results obtained are in accordance with the experimental results, which . This aspect shows the efficacythat of the finite element method is efficient for the in studying the behaviour of stud shear connector’s behavior. Finally, the capacities of shear connections obtained from the finite element analysis were are compared with to the connection strengths calculated using the American Specification (AISC-LRFD (2005)), European Code (Eurocode 4 (2004)) and Cuban Code (NR-080-2004). It this was is observed that, these specifications over estimate this value (capacities of shear connections) in many cases.Postprint (published version

On the equivalence of two deformation schemes in quantum field theory

Two recent deformation schemes for quantum field theories on the two-dimensional Minkowski space, making use of deformed field operators and Longo-Witten endomorphisms, respectively, are shown to be equivalent.Comment: 14 pages, no figure. The final version is available under Open Access. CC-B

a perspective on materials, synthesis methods and applications

The oxides of copper (CuxO) are fascinating materials due to their remarkable optical, electrical, thermal and magnetic properties. Nanostructuring of CuxO can further enhance the performance of this important functional material and provide it with unique properties that do not exist in its bulk form. Three distinctly different phases of CuxO, mainly CuO, Cu2O and Cu4O3, can be prepared by numerous synthesis techniques including, vapour deposition and liquid phase chemical methods. In this article, we present a review of nanostructured CuxO focusing on their material properties, methods of synthesis and an overview of various applications that have been associated with nanostructured CuxO

Obtención de jarabes glucosados por hidrólisis enzimática empleando almidón de sorgo CIAPR-132

La presente investigación está encaminada al estudio de la posible sustitución del maíz por el sorgo en la producción de jarabes glucosados para la industria alimenticia, considerando la evaluación de las potencialidades de dicho cereal. En este sentido se realizó un diseño experimental compuesto del tipo 2k, utilizando  el Software Statgraphics Centurion XV en elprocesamiento de los resultados del proceso desarrolladoen el laboratorio. Para ello se analizó la influenciade las variables independientes: concentración deenzima alfa amilasa (X1) en los niveles de 0,06 y 0,16%p/p, la concentración de enzima amiloglucosidasa(AMG) (X2) en los niveles de 0,18 y 0,375 %p/p ytiempo de sacarificación (X3) de 24 y 48 horas sobrelas variables respuestas °Brix y Azúcares ReductoresTotales (ART); además se determinó el rendimiento de cada experimento, obteniéndose los mejores resultados para la mayor concentración de enzima alfaamilasa, concentración de enzima AMG y tiempo de sacarificación en los menores valores. Los mejores resultados se obtuvieron para el Brix de 52,22 y ARTde 68,76%

Deformations of Quantum Field Theories on Curved Spacetimes

The construction and analysis of deformations of quantum field theories by warped convolutions is extended to a class of globally hyperbolic spacetimes. First, we show that any four-dimensional spacetime which admits two commuting and spacelike Killing vector fields carries a family of wedge regions with causal properties analogous to the Minkowski space wedges. Deformations of quantum field theories on these spacetimes are carried out within the operator-algebraic framework - the emerging models share many structural properties with deformations of field theories on flat spacetime. In particular, deformed quantum fields are localized in the wedges of the considered spacetime. As a concrete example, the deformation of the free Dirac field is studied. Second, quantum field theories on de Sitter spacetime with global U(1) gauge symmetry are deformed using the joint action of the internal symmetry group and a one-parameter group of boosts. The resulting theories turn out to be wedge-local and non-isomorphic to the initial one for a class of theories, including the free charged Dirac field. The properties of deformed models coming from inclusions of CAR-algebras are studied in detail. Third, the deformation of the scalar free field in the Araki-Wood representation on Minkowski spacetime is discussed as a motivating example.Comment: PhD thesis, University of Vienna, 2012 (advisors: J. Yngvason and G. Lechner) 107 pages, 3 figure

Experimental and theoretical investigation of ligand effects on the synthesis of ZnO nanoparticles

ZnO nanoparticles with highly controllable particle sizes(less than 10 nm) were synthesized using organic capping ligands in Zn(Ac)2 ethanolic solution. The molecular structure of the ligands was found to have significant influence on the particle size. The multi-functional molecule tris(hydroxymethyl)-aminomethane (THMA) favoured smaller particle distributions compared with ligands possessing long hydrocarbon chains that are more frequently employed. The adsorption of capping ligands on ZnnOn crystal nuclei (where n = 4 or 18 molecular clusters of(0001) ZnO surfaces) was modelled by ab initio methods at the density functional theory (DFT) level. For the molecules examined, chemisorption proceeded via the formation of Zn...O, Zn...N, or Zn...S chemical bonds between the ligands and active Zn2+ sites on ZnO surfaces. The DFT results indicated that THMA binds more strongly to the ZnO surface than other ligands, suggesting that this molecule is very effective at stabilizing ZnO nanoparticle surfaces. This study, therefore, provides new insight into the correlation between the molecular structure of capping ligands and the morphology of metal oxide nanostructures formed in their presence