Asymptotic structure of the Einstein-Maxwell theory on AdS3_{3}

The asymptotic structure of AdS spacetimes in the context of General Relativity coupled to the Maxwell field in three spacetime dimensions is analyzed. Although the fall-off of the fields is relaxed with respect to that of Brown and Henneaux, the variation of the canonical generators associated to the asymptotic Killing vectors can be shown to be finite once required to span the Lie derivative of the fields. The corresponding surface integrals then acquire explicit contributions from the electromagnetic field, and become well-defined provided they fulfill suitable integrability conditions, implying that the leading terms of the asymptotic form of the electromagnetic field are functionally related. Consequently, for a generic choice of boundary conditions, the asymptotic symmetries are broken down to $\mathbb{R}\otimes U\left(1\right)\otimes U\left(1\right)$. Nonetheless, requiring compatibility of the boundary conditions with one of the asymptotic Virasoro symmetries, singles out the set to be characterized by an arbitrary function of a single variable, whose precise form depends on the choice of the chiral copy. Remarkably, requiring the asymptotic symmetries to contain the full conformal group selects a very special set of boundary conditions that is labeled by a unique constant parameter, so that the algebra of the canonical generators is given by the direct sum of two copies of the Virasoro algebra with the standard central extension and $U\left(1\right)$. This special set of boundary conditions makes the energy spectrum of electrically charged rotating black holes to be well-behaved.Comment: 18 pages, no figure

Using Genetic Algorithms with Variable-length Individuals for Planning Two-Manipulators Motion

International Conference on Artificial Neural Networks and Genetic Algorithms. 01/01/1997. NorwichA method based on genetic algorithms for obtaining coordinated motion plans of manipulator robots is presented. A decoupled planning approach has been used; that is, the problem has been decomposed into two subproblems: path planning and trajectory planning. This paper focuses on the second problem. The generated plans minimize the total motion time of the robots along their paths. The optimization problem is solved by evolutionary algorithms using a variable-length individuals codification and specific genetic operators

Agua y Suero Fisiológico para Prevenir la Formación de Paracloroanilina

Indexación: Web of Science; Scielo.ABSTRACT: This study determined if p-chloroaniline (PCA) can be minimized by using distilled water and physiological saline solution following sodium hypochlorite but before chlorhexidine. Hypochlorite 5%, 0.5%, 0.05%, 0.005% and 0.0005% dissolved in 0.9% NaCl and in distilled water were mixed with 2% chlorhexidine for the formation of PCA. The PCA was determined using UV-VISIBLE spectrometry, with spectral curve was determined the wavelength of maximum absorption of PCA. Formed PCA absorbance was measured between 0.025%, 0.02%, 0.015%, 0.01%, 0.005% and 0.0025% hypochlorite and 2% chlorhexidine. 2% chlorhexidine and hypochlorite with physiological saline form a white precipitate which prevents the measurement of PCA. Colored PCA is formed with 0.05%, 0.005% hypochlorite aqueous dilutions and 2% chlorhexidine. The lwavelength of maximum absorption obtained was 470 nm and absorbance of PCA showed a linear decrease. 0.005% NaClO produces the least amount of PCA. The best solvent to prevent the formation of PCA during the interaction of sodium hypochlorite with chlorhexidine is distilled water.Este estudio determinó si la p-cloroanilina (PCA) puede ser minimizada mediante el uso de agua destilada y solución salina fisiológica seguido de la aplicación de hipoclorito de sodio, previo a la aplicación de clorhexidina. Hipoclorito al 5%, 0,5%, 0,05%, 0,005% y 0,0005% fue disuelto en 0,9% de NaCl y en agua destilada se mezcló con 2% de clorhexidina para la formación de PCA. El PCA se determinó mediante espectrometría UV-Visible, y con curva espectral se determinó la longitud de onda máxima del PCA. La absorbancia del PCA formado se midió con 0,025%, 0,02%, 0,015%, 0,01%, 0,005% y 0,0025% de hipoclorito y 2% de clorhexidina. La combinación de 2% de clorhexidina e hipoclorito en solución salina fisiológica forman un precipitado blanco que impide la medición del PCA. El PCA coloreado es formado con 0,05%, 0,005% diluciones acuosas de hipoclorito y 2% de clorhexidina. La longitud de onda máxima obtenida fue de 470 nm y la absorbancia del PCA mostró una disminución lineal. NaClO al 0,005% produce menor cantidad de PCA. El mejor disolvente para evitar la formación de PCA durante la interacción de hipoclorito de sodio con clorhexidina es agua destilada.http://ref.scielo.org/2kpw6

New Trends in the Control of Grid-Connected Photovoltaic Systems for the Provision of Ancillary Services

Copyright: © 2022 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/).The gradual displacement of conventional generation from the energy mix to give way to renewable energy sources represents a paradigm shift in the operation of future power systems: on the one hand, renewable technologies are, in general, volatile and difficult to predict; and on the other hand, they are usually connected to the grid through electronic power converters. This decoupling due to power converters means that renewable generators lack the natural response that conventional generation has to the imbalances between demand and generation that occur during the regular operation of power systems. Renewable generators must, therefore, provide a series of complementary services for the correct operation of power systems in addition to producing the necessary amount of energy. This paper presents an overview of existing methods in the literature that allow photovoltaic generators to participate in the provision of ancillary services, focusing on solutions based on power curtailment by modifying the traditional maximum power point tracking algorithm

Sant Cristòfol de Culla, un estudi que va més enllà de l’estètica

A la comarca de l’Alt Maestrat, a un quilòmetre de la població de Culla, s’erigeix l’ermita de Sant Cristòfol, construïda en un moment d’auge econòmic, a la fi del segle xviii. El present article es basa en l’estudi arquitectònic d’aquesta construcció. En primer lloc es presenta aquesta xicoteta, però valuosa, construcció en l’àmbit sociocultural des del qual va ser concebuda, passant en punts posteriors a la seua anàlisi arquitectònica. Des d’aquesta òptica s’analitza la seua morfologia, a través de la qual està catalogada com una de les escasses ermites saló/columnàries castellonenques. L’anàlisi dels materials i les tècniques constructives empleades i la seua genuïna composició permet apreciar la convivència de la tradició constructiva local amb l’autoria arquitectònica, encara qüestionada per reconeguts historiadors. Més enllà de la mera descripció escrita, l’article aporta un detallat treball d’aixecament de plànols, l’anàlisi dels quals permet relacionar la seua mètrica amb les proporcions clàssiques.Saint Christopher’s chapel lies one kilometre away from Culla, in the Alt Maestrat region (Spain). It was built at the end of the 18 th century, in a moment of economic wealth. This article tackles the architectural study of the said chapel. Firstly, the little but nonetheless cherished construction is presented in the socio-cultural context where it was envisaged, moving later on to its architectural analysis. Following this perspective, the morphology of the chapel is addressed, rendering the construction as one of the very few chapels in Castelló with a column-based structure. The analysis of the materials and the construction techniques applied, as well as its unique composition, makes it possible to appreciate the coexistence of the local construction tradition together with the idiosyncratic architectural authorship of the chapel, still in question among renowned historians. Beyond the mere description of the construction, this paper brings a detailed work on its topographic site plans, whose analysis allows connecting the measures of the chapel to classic proportions

Lectura de las proporciones utilizadas por el maestro Ayora en las iglesias salón valencianas del XVIII

En el presente artículo se analiza la obra del Maestro Arquitecto Joseph Ayora y su saga, y su aportación a los templos valencianos del XVIII, concebidos siguiendo el modelo hallenkirchen. Nacido en un pequeño pueblo de Teruel pronto dejará indicios de su actividad como tracista y constructor en la provincia de Castellón, donde al menos se le relaciona con once templos, de los cuales cinco son columnarios. En las Iglesias de Castell de Cabres y Cinctorres ha sido documentada la autoría de sus trazas, en Vila-real su aportación fue parcial, mientras que en las de Benifairó de les Valls y Suera se le presupone. El análisis gráfico basado en el exhaustivo levantamiento de planos de la obra patrimonial construida y en el estudio comparado de sus trazados reguladores, su métrica y su composición, se muestra como una herramienta veraz, capaz de esclarecer presuntas autorías y desvelar el patrón de diseño de los tracistas.In the present article it is analyses the building work of the family’s Master Architect Joseph Ayora, and his contribution to the Valencian temples of the XVIIIth conceived following the hallenkirchen model. This master mason was born in a little village of Teruel, he will leave early indications of his activity as tracer and builder in Castellón’s province, where at least he is related to eleven temples, of which five are hall churches. In the Churches of Castell de Cabres and Cinctorres has been documented the authorship of its traces, in Vila-real its contribution was partial, whereas in the churches of Benifairó de les Valls and Suera it is presupposed. The graphical analysis based on the exhaustive raising of planes of the patrimonial constructed work and on the compared study of its regulatory tracings, its metrics and its composition, appears as a veracious tool, capable of clarifying supposed authorships and reveals the template of design of the tracers