A note on the Gauge Symmetries of Unimodular Gravity

The symmetries of Unimodular Gravity are clarified somewhat.Comment: 4 pages, v2: acknowledgments correcte

Método interactivo para la extrapolación de ondas sísmicas. Aplicación a la prospección geofísica (Parte 2)

Este artículo es continuación del publicado en el número 2 de la revista "Anales de Ingeniería Mecánica"(diciembre 1982), sobre los métodos de análisis sísmico por reflexión. Como allí se indicó, con estos métodos se pretende determinar la geometría de los horizontes sísmicos en una determinada sección así como las características físicas de las interfases que separa. En el presente artículo se introducen mejoras en lo que se refiere a tiempo compucional y tipos de campos de velocidades. En este nuevo método propuesto para la resolución del proceso de emigración, mediante un método gráfico interactivo, pueden señalarse como ventjas fundamentales, las siguientes: a) Tiempo de resolución acorde con la complejidad del campo de velocidades, produciéndose economía de dicho tiempo, sobre todo en los casos sencillos; b) El número de elementos de la malla y las dimensiones de los mismos son función de la complejidad del campo de velocidades; c) El estudio en cada elemento se realiza de forma general e independiente. General, en cuanto a que los resultados que se obtienen en cada elemento son valores globales, referidos a la malla y al problema en conjunto, e independiente, puesto que los datos necesarios en cada elemento se obtienen a partir de valores nodales; d) Posibilidad de resolución del problema para un campo de velocidades cualesquiera, y por lo tanto, incluyendo los casos de discontinuidades de velocidad, que se evalúan mediante la ley de Snell; e) Posibilidad de extender el método al caso de tres dimensiones, sin más que elegir como elementos de la malla, tetraedros en vez de triángulos. En conjunto, resulta un método flexible, de fácil utilización e interpretación de resultados

Legislación antiterrorista comparada después de los atentados del 11 de septiembre y su incidencia en el ejercicio de los derechos fundamentales

Este ARI analiza las novedades legislativas que en materia de lucha contra el terrorismo se vienen sucediendo en diferentes países de nuestro entorno tras los atentados terroristas del 11 de septiembre, y más tarde los del 11 de marzo y 7 de julio, y el impacto que esa nueva normativa tiene en el ámbito de los derechos y libertades fundamentales de las sociedades abiertas. Asimismo, se efectúa un breve análisis de su repercusión en nuestro país. Los atentados terroristas del 11 de septiembre de 2001 en los EEUU, 11 de marzo de 2004 en Madrid, y 7 de julio de 2005 en Londres han obligado a las democracias occidentales a adoptar distintos instrumentos normativos encaminados a reforzar su acción en la lucha contra el terrorismo que en muchos casos han supuesto una autentica conculcación de derechos fundamentales como la libertad y seguridad personales, la tutela judicial efectiva, la intimidad, el secreto de las comunicaciones telefónicas o a través de Internet, etc. Asimismo, han aumentado los poderes y facultades de los servicios de inteligencia y la policía en la lucha contra el terrorismo y han afectado de manera singular al estatus jurídico de los extranjeros residentes en sus territorios, quienes, en ocasiones, han visto cercenados sus derechos más fundamentales de una forma absolutamente arbitraria

Quantum Corrections to Unimodular Gravity

The problem of the cosmological constant appears in a new light in Unimodular Gravity. In particular, the zero momentum piece of the potential (that is, the constant piece independent of the matter fields) does not automatically produce a cosmological constant proportional to it. The aim of this paper is to give some details on a calculation showing that quantum corrections do not renormalize the classical value of this observable.Comment: 34 page

Indicators and Estimators in P-Adaptive Boundary Elements

The paper presents the possibility of implementing a p-adaptive process with the B.E.M. Although the exemples show that good results can be obtained with a limited amount of storage and with the simple ideas explained above, more research is needed in order to improve the two main problems of the method, i.e.: the criteria of where to refine and until what degree. Mathematically based reasoning is still lacking and will be useful to simplify the decission making. Nevertheless the method seems promising and, we hope, opens a path for a series of research lines of maximum interest. Although the paper has dealt only with plane potential problem the extension to plane elasticity as well as to 3-D potential problem is straight-forward

Design of a test bench for measuring friction force in a piston-cylinder system

In the present work, design of a first approach of a test bench prototype for measuring friction in a piston-cylinder system is presented. The bench consists of a motor, belt and pulley transmission, crank mechanism, a piston, a cylinder and a lubrication system. Friction will be determined by means of strain gages placed on the connecting rod of the mechanism. The bench also includes a phonic wheel for acquiring angular speed and angular position signals of the crank. In future research, friction will be studied for different surface finishes obtained by means of honing and plateau honing. Honing processes provide a crosshatch pattern that holds oil and helps lubrication of piston and rings. Honing conditions will be selected with the goal of minimizing friction. Friction is directly related to energy consumption of an engine and, thus, to its environmental impact. Keywords: test bench, friction, piston-cylinder system, honing, roughness.Postprint (published version

Retos asistenciales en la atención al paciente traumatizado en España. La necesidad de implementación de la evidencia científica incluyendo la prevención secundaria

Producción CientíficaThe mortality of trauma patients has improved significantly in recent decades due to a combination of factors: medical care, educational campaigns and structural changes. Generalization of both out-of hospital emergence medical services and the hospital care in specific centers for traumatized has undoubtedly contributed to this decline, but other factors such as periodic campaigns to prevent workplace and traffic accidents, as well as improvements in the road network have played a key role. The challenge now is to contain mortality, for which is essential an analysis of the situation to detect potential areas of improvement. The application of diagnostic or therapeutic actions with scientific evidence is associated with lower mortality, but as in other areas of medicine, the application of scientific evidence in trauma patients is barely 50%. Moreover, nearly 90% of trauma deaths occur in the crash site or during the first 72 h of hospitalization, the vast majority as a result of injuries incompatible with life. In these circumstances it is clear that prevention is the most cost-effective activity. As medical practitioners, our role in prevention is mainly focused on the secondary prevention to avoid recidivism, for which it is necessary to identify the possible risk factors (frequently alcohol, illegal drugs, psychotropic medication, etc.) and implement a brief motivational intervention. This activity can reduce recidivism by nearly 50%. In Spain, the activity in this field is negligible; therefore, measures should be implemented for dissemination of secondary prevention in trauma

Structural study of water/alcohol mixtures adsorbed in MFI and MEL porosils

Ethanol and other biofuels produced during biomass conversion must be separated from the fermentation broth (mainly water) before being used as a fuel. This can be addressed by adsorption-based separation using porous materials. The key objective of this study is to obtain a molecular understanding of water and alcohol adsorption in pure-silica zeolites, particularly in silicalite-1 (MFI-type zeolite) and silicalite-2 (MEL-type zeolite). Molecular simulation techniques are used for this purpose. They provide information on the configuration of the fluids, and so the microscopic network structure of the adsorbed polar molecules can be characterized by using a specific criterion of hydrogen bonding formation. We conducted Grand-Canonical Monte Carlo simulations to compute the adsorption isotherms of pure short alcohols and water and from the liquid alcohol/water binary mixtures throughout the composition range. Despite MFI and MEL being structurally very similar, we found differences in adsorption, which are related to the underlying molecular behavior. While water intrusion occurs by applying pressure due to stronger water-water than water–silicalite interactions, notable water adsorption from the mixture occurs first by hydrogen bond formation with the adsorbed alcohols and then by self-association. A higher degree of water clustering in MEL compared to MFI zeolite, promoted by its straight channels, leads to relatively lower uptakes of water in the latter zeolite (in favor of alcohol molecules).The authors acknowledge the support from the Agencia Estatal de Investigación and Fondo Europeo de Desarrollo Regional (FEDER) under Grant No. PID2020-115722 GB-C21. Funding for open access charge: Universidad de Huelva / CBU

Different coordination modes of an aryl-substituted hydrotris(pyrazolyl) borate ligand in rhodium and iridium complexes

Complexes TptolRh(C2H4)2 (1a) and TptolRh(CH2C(Me)C(Me)CH2) (1b) have been prepared by reaction of KTptol with the appropriate [RhCl(olefin)2]2 dimer (Tptol means hydrotris(3-p-tolylpyrazol-1-yl)borate). The two complexes show a dynamic behaviour that involves exchange between κ2 and κ3 coordination modes of the Tptol ligand. The iridium analogue, TptolIr(CH2C(Me)CHCH2) (2) has also been synthesized, and has been converted into the Ir(III) dinitrogen complex [(κ4-N,N',N'',C-Tptol)Ir(Ph)(N2) (3) by irradiation with UV light under a dinitrogen atmosphere. Compound 3 constitutes a rare example of Ir(III)-N2 complex structurally characterized by X-ray crystallography. Its N2 ligand can be easily substituted by acetonitrile or ethylene upon heating and denticity changes in the Tptol ligand, from κ4-N,N',N'',C (monometallated Tptol, from now on represented as Tptol′) to κ5-N,N′,N″,C,C″ (dimetallated Tp tol ligand, represented as Tptol″) have been observed. When complex 3 is heated in the presence of acetylene, dimerization of the alkyne takes place to yield the enyne complex [(κ5-N,N′,N′′,C,C′-Tp tol)Ir(CH2CHCCH), 7̧ in which the unsaturated organic moiety is bonded to iridium through the carbon-carbon double bond.Ministerio de Educación y Ciencia CTQ2007-62814Consolider-Ingenio 2010 CSD2007-00006Junta de Andalucía FQM-3151, FQM-672CONACYT 22934