Covariant definition of Double Null Data and geometric uniqueness of the characteristic initial value problem

The characteristic Cauchy problem of the Einstein field equations has been recently addressed from a completely abstract viewpoint by means of hypersurface data and, in particular, via the notion of double null data. However, this definition was given in a partially gauge-fixed form. In this paper we generalize the notion of double null data in a fully diffeomorphism and gauge covariant way, and show that the definition is complete by proving that no extra conditions are needed to embed the double null data in some spacetime. The second aim of the paper is to show that the characteristic Cauchy problem satisfies a geometric uniqueness property. Specifically, we introduce a natural notion of isometry at the abstract level such that two double null data that are isometric in this sense give rise to isometric spacetimes.Comment: 36 pages, 1 figur

Wide-gene expression analysis of lipid-relevant genes in nutritionally challenged gilthead sea bream (Sparus aurata)

Disturbances of lipid metabolism are a major problem in livestock fish and the present study analysed the different tissue expression patterns and regulations of 40 lipid-relevant genes in gilthead sea bream. Nineteen sequences, including fatty acid elongases (4), phospholipases (7), acylglycerol lipases (8) and lipase-maturating enzymes (1), were new for gilthead sea bream (GenBank, JX975700-JX975718). Up to six different lipase-related enzymes were highly expressed in adipose tissue and liver, which also showed a high expression level of δ6 and δ9 desaturases. In the brain, the greatest gene expression level was achieved by the very long chain fatty acid elongation 1, along with relatively high levels of δ9 desaturases and the phospholipase retinoic acid receptor responder. These two enzymes were also expressed at a high level in white skeletal muscle, which also shared a high expression of lipid oxidative enzymes. An overall down-regulation trend was observed in liver and adipose tissue in response to fasting following the depletion of lipid stores. The white skeletal muscle of fasted fish showed a strong down-regulation of δ9 desaturases in conjunction with a consistent up-regulation of the >lipolytic machinery> including key enzymes of tissue fatty acid uptake and mitochondrial fatty acid transport and oxidation. In contrast, the gene expression profile of the brain remained almost unaltered in fasted fish, which highlights the different tissue plasticity of lipid-related genes. Taken together, these findings provide new fish genomic resources and contribute to define the most informative set of lipid-relevant genes for a given tissue and physiological condition in gilthead sea bream. © 2014 Elsevier B.V.This research was funded by the Spanish MICINN through AQUAFAT (AGL2009-07797; predictive modelling of flesh fatty acid composition in cultured fish species with different muscle lipid contents) and AQUAGENOMICS (CSD2007-00002, improvement of aquaculture production by the use of biotechnological tools) projects. Additional funding was obtained from EU project ARRAINA (KBBE-2011-5-288925, advanced research initiatives for nutrition and aquaculture).Peer Reviewe

Design of a Packed-Bed Column and a Sieve Tray Tower for Ethanol Absorption. 2. Sieve Tray Tower Design

En el presente trabajo se realizó el diseño de una torre de bandejas perforadas para efectuar un proceso de absorción de etanol gaseoso empleando agua como solvente. El resultado de costo obtenido se comparó con el costo de una columna empacada diseñada por (Pérez, Pérez, & Liaño, 2019) con el fin de seleccionar el equipo más adecuado desde el punto de vista económico. La torre tuvo un diámetro de 0,404 m, una caída de presión del gas de 0,783 kPa/bandeja –inferior a la máxima caída de presión establecida por el sistema (1,0 kPa/bandeja)– y un flujo de arrastre de 0,018 kg/s (64,8 kg/h), el cual puede calificarse como aceptable. La eficiencia de la bandeja de Murphree corregida por flujo de arrastre fue igual a 0,829, mientras que la torre presentó 11 bandejas o etapas en total. La torre de bandejas perforadas tuvo un costo aproximado de usd 15.315, siendo 1,44 veces inferior al costo de la columna empacada determinado por (Pérez, Pérez, & Liaño, 2019). Se concluye que resulta más factible, desde el punto de vista económico, adquirir la torre de bandejas perforadas para llevar a cabo el proceso de absorción establecido en este proyecto.This work explains the design of a sieve tray tower for gaseous ethanol absorption using water as solvent. The resulting cost was compared with that of the packed column designed by (Pérez, Pérez, & Liaño, 2019), in order to select the most suitable equipment from an economic point of view. The tower had a diameter of 0.404 m, a gas pressure drop of 0.783 kPa/tray, which is inferior to the maximum pressure drop established by the system (1.0 kPa/tray), and the entrainment flow had a value of 0.018 kg/s (64.8 kg/h), which can be considered acceptable. The entrainment-corrected Murphree tray efficiency was 0.829, while the tower had 11 trays or stages in total. The sieve tray tower had an approximate cost of usd 15,115, being 1.44 times lower than the cost of the packed column determined by (Pérez, Pérez, & Liaño, 2019). From an economic point of view, this work concludes that it is more feasible to acquire the sieve tray tower to carry out the absorption process established in this project

A multi-granular linguistic model to evaluate the suitability of installing an ERP system

The use of Enterprise Resource Planning (ERP) has shown clearly useful and economically profitable in most very large organizations which manage a great deal of data in their information systems. Nevertheless, the decision of installing an ERP system is not easy and it depends on the size, future profits and other features of the companies. The assessments of the parameters (features, aspects) used to evaluate the suitability of the ERP may be vague and imprecise because they are usually perceptions of the experts. We propose the use of linguistic information to assess these parameters due to the fact that it is very suitable to model and manage human perceptions. In addition, it may be that each expert has a different knowledge about each parameter and prefers to express his/her preferences in his/her own linguistic term set. Therefore, to manage the evaluation problem of installing an ERP, in this contribution we present a multi-granular linguistic evaluation model that covers these necessities

A multi-granular linguistic model to evaluate the suitability of installing an ERP system

The use of Enterprise Resource Planning (ERP) has shown clearly useful and economically profitable in most very large organizations which manage a great deal of data in their information systems. Nevertheless, the decision of installing an ERP system is not easy and it depends on the size, future profits and other features of the companies. The assessments of the parameters (features, aspects) used to evaluate the suitability of the ERP may be vague and imprecise because they are usually perceptions of the experts. We propose the use of linguistic information to assess these parameters due to the fact that it is very suitable to model and manage human perceptions. In addition, it may be that each expert has a different knowledge about each parameter and prefers to express his/her preferences in his/her own linguistic term set. Therefore, to manage the evaluation problem of installing an ERP, in this contribution we present a multi-granular linguistic evaluation model that covers these necessities

R-SQL: An SQL Database System with Extended Recursion

The relational database language SQL:1999 standard supports recursion, but thisapproach is limited to the linear case. Moreover, mutual recursion is not supported,and negation cannot be combined with recursion. We designed the language R-SQLto overcome these limitations in [ANSS13], improving termination properties in re-cursive definitions. In addition we developed a proof of concept implementation ofan R-SQL system. In this paper we describe in detail an improved system enhanc-ing performance. It can be integrated into existing RDBMS’s, extending them withthe aforementioned benefits of R-SQL. The system processes an R-SQL databasedefinition obtaining its extension in tables of an RDBMS (such as PostgreSQL andDB2). It is implemented in SWI-Prolog and it produces a Python script that, uponexecution, computes the result of the R-SQL relations. We provide some perfor-mance results showing the efficiency gains w.r.t. the previous version. We alsoinclude a comparative analysis including some representative relational a deductive systems

Support measures in the banking sector: loan moratoria

This article presents a detailed analysis of the loan moratoria. The first part of the article describes the characteristics of the five types of moratoria and how the numbers of applications made and moratoria granted have evolved to date. It then outlines the status of the existing moratoria and the classification of loans whose moratoria have expired. In the second part of the article, an econometric analysis is performed to determine the impact of borrower and bank characteristics on the probability of loans being subject to moratoria, on the type and duration of the moratoria and on the classification of loans when the moratoria have expired. The results suggest that vulnerable households, those in regions most affected by the pandemic and lower income households are generally subject to legislative moratoria for longer or are more likely to transfer to non-legislative moratoria when the former expire. They also suggest that, when the moratoria expire, these households’ loans are more likely to be classified as Stage 2 (a significant increase in credit risk) or non-performing

Handling input voltage frequency variations in power factor correctors with precalculated duty cycles

Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. F. Lopez-Colino, A. Sanchez, G. Alvarez, A. de Castro, and J. Garrido. "Handling input voltage frequency variations in power factor correctors with precalculated duty cycles", in IEEE 15th Workshop on Control and Modeling for Power Electronics (COMPEL), 2014, pp. 1-5The use of precalculated duty cycles for power factor correction leads to a significant simplification of the design and a reduction of the final cost. There are previous proposals for handling non-nominal conditions such as input voltage or load variations. However, there are no proposals for handling input frequency variations, which have an important impact in the power factor. This paper measures this impact and includes a simple loop to handle the variations of the input frequency. The results show that the introduction of this loop keeps the power factor values around those obtained in nominal conditions.This work has been supported by the Spanish Ministerio de Ciencia e Innovación under project TEC2013-43017-R

Fotobiorreactor de doble lazo con desgasificador plano

Número de publicación: ES2150389 A1 (16.11.2000) También publicado como: ES2150389 B1 (01.07.2001) Número de Solicitud: Consulta de Expedientes OEPM (C.E.O.) P9900115 (21.01.1999)Un dispositivo en material transparente para el cultivo de microorganismos fotosintéticos acuáticos, que consta de un receptor solar (sistema tubular a dos niveles optimizado) y un sistema de impulsión (burbujeo de aire en un desgasificador plano), y que es operable tanto en continuo como en discontinuo, permitiendo la inyección de dióxido de carbono y el control del pH y de la concentración de oxígeno disuelto en el cultivo. El fotobiorreactor puede ser aplicado tanto para la producción de biomasa y bio-moléculas de interés a partir de microorganismos foto-autotróficos, como para cualquier proceso que se favorezca o necesite el aporte de energía por radiación.Universidad de Almerí