Rotating relativistic stars: matching conditions and kinematical properties

In the framework of general relativity, a description of the matching conditions between two rotating perfect fluids spacetimes in terms of the kinematical properties of the fluids is introduced. The Einstein and Darmois equations are written using coordinates adapted to the boundary separating both spacetimes. The functions appearing in the equations have an immediate physical interpretation. The analysis is extended to the case of matching a perfect fluid spacetime (star interior) with a vacuum spacetime (gravitational field outside the star). By solving a boundary problem for a first order partial differential equation (‘‘master equation’’) we define an exterior tetrad such that the matching conditions and the Einstein equations, for this case, reproduce those of the two-fluid problem. The formalism is applied to a particular static spherically symmetric star and to the Kerr metric

IPSC differentiation into ependymal progenitors to treat ventricular damage during hydrocephalus

Introduction: During both obstructive congenital hydrocephalus and post-hemorrhagic hydrocephalus additional pathological events are intimately associated with their ethiology: a) a detrimental inflammatory response; b) severe damage of the underlying periventricular nervous tissue, including white matter, and c). Therapeutic approaches have been directed to overcome a) and b), however recovery of damaged neuroepithelium/ependyma is, in our present, an important therapeutic gap. Methods: Human and mouse induced pluripotent stem cells (iPSC) have been artificially differented into ependymal progenitors. Intracerebroventricular (ICV) injections of iPCS are performed ex vivo and in vivo in the damaged ventricular wall. Their integration and differentiation has been studied by immunohistochemistry and histopathological analysis. Results: Mice and human ependymal progenitors are able to integrate and differentiate into ependyma in damaged ventricular wall. Stage of ependymal differentiation by the time of the injection defined different degrees of integration. Conclusions: IPSC appear to be a good ependymal progenitor source with no ethical controversy associated.RyC 2014-16980 Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Effects of foliar application of a byproduct of the two-step olive oil mill process on maize yield

The main objective of this work was to study the effect of foliar fertilization at different doses with a byproduct of the two-step olive oil mill process on the productivity and quality of maize crops (Zea mays, L. cv. Tundra) located in Lora del Río, near Sevilla (Andalusia, Spain). Foliar fertilizer was applied four times during the season and three different concentrations were tested. Foliar fertilization increased leaf soluble carbohydrate contents, chlorophyll A and B and carotenoids, and increased the leaf concentrations of N, K, Fe, Mn and Zn. Yield was significantly increased by 24% to 14.9 t $\cdot$ ha-1 by the highest dosage of the byproduct, which also caused a 22% increase in kernel number and a 19% increase in grain protein content.Effet sur le maïs de l'application foliaire d'un sous-produit du processus d'élaboration de l'huile d'olive en deux étapes. L'objectif principal de ce travail était d'étudier l'effet de la fertilisation foliaire à doses différentes avec un sous-produit du processus d'élaboration de l'huile d'olive en deux étapes sur la production et qualité de la récolte du maïs (Zea mays, L. cv. Tundra) dans la région de Lora del Río, près de Séville (Andalousie, Espagne). L'engrais foliaire a été appliqué quatre fois pendant la saison et trois concentrations différentes ont été testées. Cet engrais a augmenté les niveaux d'hydrates de carbone, de chlorophylle A et B et de caroténoïdes et des éléments nutritifs N, K, Fe, Mn et Zn dans la feuille. Le rendement a été augmenté de 24 % et a atteint 14,9 t $\cdot$ ha-1 avec la dose la plus élevée de sous- produit et s'est accompagné d'une augmentation de 22 % du nombre de grains et de 19 % du contenu en protéines du grain

Fotografía & retrato

La fotografía nos presenta a gritos el triunfo de lo ficticio y artificial sobre lo humano y natural. La deformación es entonces cuando adquiere un valor irrefutable y se presenta en la vida moderna como pattern indiscutible para cualquier modo de expresión. Con este artículo deseo entrar en el debate sobre la función que la fotografía ha mantenido en el ámbito del retrato y la visión particular que ha incluido en la estética de este último

Hypercube algorithms on mesh connected multicomputers

A new methodology named CALMANT (CC-cube Algorithms on Meshes and Tori) for mapping a type of algorithm that we call CC-cube algorithm onto multicomputers with hypercube, mesh, or torus interconnection topology is proposed. This methodology is suitable when the initial problem can be expressed as a set of processes that communicate through a hypercube topology (a CC-cube algorithm). There are many important algorithms that fit into the CC-cube type. CALMANT is based on three different techniques: (a) the standard embedding to assign the processes of the algorithm to the nodes of the mesh multicomputer; (b) the communication pipelining technique to increase the level of communication parallelism inherent in the CC-cube algorithms; and (c) optimal message-scheduling algorithms proposed in this work in order to avoid conflicts and minimizing in this way the communication time. Although CALMANT is proposed for multicomputers with different interconnection network topologies, the paper only focuses on the particular case of meshes.Peer ReviewedPostprint (published version

A study of the communication cost of the FFT on torus multicomputers

The computation of a one-dimensional FFT on a c-dimensional torus multicomputer is analyzed. Different approaches are proposed which differ in the way they use the interconnection network. The first approach is based on the multidimensional index mapping technique for the FFT computation. The second approach starts from a hypercube algorithm and then embeds the hypercube onto the torus. The third approach reduces the communication cost of the hypercube algorithm by pipelining the communication operations. A novel methodology to pipeline the communication operations on a torus is proposed. Analytical models are presented to compare the different approaches. This comparison study shows that the best approach depends on the number of dimensions of the torus and the communication start-up and transfer times. The analytical models allow us to select the most efficient approach for the available machine.Peer ReviewedPostprint (published version

Lineability criteria, with applications

Lineability is a property enjoyed by some subsets within a vector space X. A subset A of X is called lineable whenever A contains, except for zero, an infinite dimensional vector subspace. If, additionally, X is endowed with richer structures, then the more stringent notions of dense-lineability, maximal dense-lineability and spaceability arise naturally. In this paper, several lineability criteria are provided and applied to specific topological vector spaces, mainly function spaces. Sometimes, such criteria furnish unified proofs of a number of scattered results in the related literature. Families of strict-order integrable functions, hypercyclic vectors, non-extendable holomorphic mappings, Riemann non-Lebesgue integrable functions, sequences not satisfying the Lebesgue dominated convergence theorem, nowhere analytic functions, bounded variation functions, entire functions with fast growth and Peano curves, among others, are analyzed from the point of view of lineability.Plan Andaluz de Investigación (Junta de Andalucía)Ministerio de Economía y Competitivida

Assessing the relationship between R&D subsidy, R&D cooperation and absorptive capacity: an investigation on the manufacturing Spanish case

Private companies want to eliminate outgoing spillovers while policymakers seek to maximize them. With subsidized R&D cooperation agreements both agents partially achieve their objectives. For this reason, in Europe, policymakers grant subsidies for R&D activities with the condition of establishing R&D cooperation agreements. This study explores the relationship of complementarity between R&D subsidy, R&D cooperation and absorptive capacity in the context of its contribution to labor productivity of enterprises. The data used comes from the Technological Innovation Panel (PITEC), managed by the Spanish National Statistics Institute. We selected manufacturing companies in the period 2008–2013. We evaluate the existence of complementarity through the systems approach and the interaction approach. The econometric technique that we used to estimate the coefficients of our empirical model was maximum-likelihood random effects. As a consequence of the low absorptive capacity of Spanish manufacturing firms we find that R&D subsidies and R&D cooperation agreements are not complementary variables, i.e., receiving public subsidies as a result of establishing R&D cooperation agreements has a lower impact on productivity than the sum of the individual impacts of R&D cooperation and R&D subsidies. In consequence, this result calls into question the convenience of using subsidized R&D cooperation agreements as a tool for promoting innovation in EU countries as there are notable differences between the companies in these countries in terms of absorption capacity