On the magnetic field evolution timescale in superconducting neutron star cores

We revisit the various approximations employed to study the long-term evolution of the magnetic field in neutron star cores and discuss their limitations and possible improvements. A recent controversy on the correct form of the induction equation and the relevant evolution timescale in superconducting neutron star cores is addressed and clarified. We show that this ambiguity in the estimation of timescales arises as a consequence of nominally large terms that appear in the induction equation, but which are, in fact, mostly irrotational. This subtlety leads to a discrepancy by many orders of magnitude when velocity fields are absent or ignored. Even when internal velocity fields are accounted for, only the solenoidal part of the electric field contributes to the induction equation, which can be substantially smaller than the irrotational part. We also argue that stationary velocity fields must be incorporated in the slow evolution of the magnetic field as the next level of approximation.Comment: 6 pages, version accepted by MNRA

On the convexity of Relativistic Ideal Magnetohydrodynamics

We analyze the influence of the magnetic field in the convexity properties of the relativistic magnetohydrodynamics system of equations. To this purpose we use the approach of Lax, based on the analysis of the linearly degenerate/genuinely non-linear nature of the characteristic fields. Degenerate and non-degenerate states are discussed separately and the non-relativistic, unmagnetized limits are properly recovered. The characteristic fields corresponding to the material and Alfv\'en waves are linearly degenerate and, then, not affected by the convexity issue. The analysis of the characteristic fields associated with the magnetosonic waves reveals, however, a dependence of the convexity condition on the magnetic field. The result is expressed in the form of a generalized fundamental derivative written as the sum of two terms. The first one is the generalized fundamental derivative in the case of purely hydrodynamical (relativistic) flow. The second one contains the effects of the magnetic field. The analysis of this term shows that it is always positive leading to the remarkable result that the presence of a magnetic field in the fluid reduces the domain of thermodynamical states for which the EOS is non-convex.Comment: 14 pages. Submitted to Classical and Quantum Gravit

Argentine contributions to crop ecophysiology

La ecofisiología de cultivos en Argentina tiene una amplia y reconocida trayectoria no solo en al ámbitonacional sino también internacionalmente a través de una importante cantidad de trabajos publicadospor distintos grupos de investigación Argentinos en revistas científicas y técnicas de reconocimientomundial. En este trabajo se ha intentado poner de relevancia el impacto que la investigación enecofisiología de cultivos realizada en Argentina ha tenido en la comunidad científica internacional y laaplicación a nivel local y regional en las áreas de transferencia tecnológica. Para ello, se han cuantificadolos aportes al conocimiento global a través de publicaciones primarias en revistas indexadas en la ?Webof Science? y se ha hecho un análisis de la calidad de estas publicaciones. Los resultados muestran losimportantes aportes al conocimiento de la funcionalidad de los cultivos a partir de los estudios de laecofisiología desarrollada por grupos argentinos, los que en muchos casos se tradujeron en aportes almanejo de los cultivos, no solo a través de conferencias técnicas y publicaciones en revistas técnicasy/o de divulgación, sino también a través de herramientas diseñadas para la toma de decisiones en lossistemas de producción.Crop ecophysiology in Argentina has a wide and recognized impact at national as well as at international level, through a significant amount of works published by different Argentine research groups in scientific journals of worldwide recognition. In this work, we tried to highlight the impact that research in crop ecophysiology in Argentina has had on the international scientific community and the application of the knowledge produced by local groups of ecophysiology in the areas of technology transfer. For this, the contributions to global knowledge have been quantified through primary publications in indexed journals in the “Web of Science” as well as through the analysis of the quality of these publications. The results showed the important contribution of the Argentine ecophysiology studies to the knowledge of the functionality of the crops, which in many cases were translated into contributions to the crop management,not only through conferences for farmers and technicians and publications in technical journals, but also through tools designed for decision making in production systems at local and regional level.Fil: Slafer, Gustavo Ariel. Universitat de Lleida; España. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentina. Institució Catalana de Recerca i Estudis Avancats; EspañaFil: Hall, Antonio Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Miralles, Daniel Julio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; Argentin

The use of employee participation in the USA and Spanish companies

This article presents a description of employee participation in Spain. The number of published papers in English about Spain regarding this subject is very low, and even lower by Spanish authors. In short, we can say that there is hardly any knowledge regarding employee participation in Spain in both the European and American settings. This paper summarized the results of a research project we carried out whose objective was to compare employee participation using samples from large American and Spanish companies following the works of Edward E. Lawler and his team. Our aim is to have professionals and researchers throughout the world better understand the actual situation in our country

Experimental determination of drift loss from a cooling tower with different drift eliminators using the chemical balance method

The existence of cooling towers arises from the need to evacuate power to the environment from engines, refrigeration equipment and industrial processes. Water drift emitted from cooling towers is objectionable for several reasons, mainly due to human health hazards. It is common practice to fit drift eliminators to cooling towers in order to minimise water loss from the system. The presence of the drift eliminator mainly affects two aspects of cooling towers: their thermal performance and the amount of water drift loss. This paper experimentally studies the drift loss emissions from a cooling tower without drift eliminator and fitted with six different drift eliminators. Chemical Balance is the selected method and Australian Standard methodology is taken as a reference. Some modifications are proposed to reduce uncertainty by increasing the duration of the test and the number of water samples. Installation of a drift eliminator, even in the worst case, reduces the water drift level to less than half of the situation without the eliminator. The water drift losses obtained with the different drift eliminators installed at the pilot plant, from 0.0118% to 0.161%, are within the range generally reflected in the literature. Finally, a criterion for designing drift eliminators in order to optimise both the collection efficiency and the cooling tower's thermal performance is proposed.This research has been partially financed by the project DPI2007-66551-C02-01 grant from the “Dirección General de Industria, M. de Ciencia y Tecnología”, the project 2I05SU0029 grant of the “Secretaría General de la Consejerí de Educación y Cultura de la C.A. de la Región de Murcia” and the HRS Spiratube Company, Murcia (Spain)

Crust-magnetosphere coupling during magnetar evolution and implications for the surface temperature

We study the coupling of the force-free magnetosphere to the long-term internal evolution of a magnetar. We allow the relation between the poloidal and toroidal stream functions - that characterizes the magnetosphere - to evolve freely without constraining its particular form. We find that, on time-scales of the order of kyr, the energy stored in the magnetosphere gradually increases, as the toroidal region grows and the field lines expand outwards. This continues until a critical point is reached beyond which force-free solutions for the magnetosphere can no longer be constructed, likely leading to some large-scale magnetospheric reorganization. The energy budget available for such events can be as high as several $10^{45}\,$erg for fields of $10^{14}\,$G. Subsequently, starting from the new initial conditions, the evolution proceeds in a similar manner. The time-scale to reach the critical point scales inversely with the magnetic field amplitude. Allowing currents to pass through the last few meters below the surface, where the magnetic diffusivity is orders of magnitude larger than in the crust, should give rise to a considerable amount of energy deposition through Joule heating. We estimate that the effective surface temperature could increase locally from $\sim 0.1\,$keV to $\sim 0.3 - 0.6\,$keV, in good agreement with observations. Similarly, the power input from the interior into the magnetosphere could be as high as $10^{35} - 10^{36}\,$erg/s, which is consistent with peak luminosities observed during magnetar outbursts. Therefore, a detailed treatment of currents flowing through the envelope may be needed to explain the thermal properties of magnetars.Comment: 9 pages, 9 figures; updated version accepted for publication by MNRA

On the influence of psychrometric ambient conditions on cooling tower drift deposition

Water drift emitted from cooling towers is objectionable for several reasons, mainly due to human health reasons. A numerical model to study the influence of sychrometric ambient conditions on cooling tower drift deposition was developed. The mathematical model presented, consisting of two coupled sets of conservation equations for the continuous and discrete phases, was incorporated in the general purpose CFD code Fluent. Both experimental plume performance and drift deposition were employed to validate the numerical results. This study shows the influence of variables like ambient dry bulb temperature, ambient absolute humidity and droplet exit temperature from cooling tower on the drift evaporation (and therefore deposition) and on the zone affected by the cooling tower. The stronger effect detected corresponds to the ambient dry bulb temperature. When a higher ambient temperature was present, deposition was lower (evaporation was therefore higher) and the zone affected by the cooling tower was smaller. The influence of the other two variables included in the study was weaker than the one corresponding to the dry bulb ambient temperature. A high level of ambient absolute humidity increased drift deposition and also the size of the zone affected by the cooling tower. Finally, a high level of droplet exit temperature decreased deposition and increased the zone affected by the cooling tower

Título: Panegyrico en honor de San Estevan proto-martir, predicado en su dia, y parroquial de Valencia

Texto a dos col.Sign. : [A]-C4Notas a pie de pag. y reclamosPort. con grab. xil.Letras iniciales decoradas y frisos tip. decorativo