Cosmological solutions in F(R) Horava-Lifshitz gravity

At the present work, it is studied the extension of F (R) gravities to the new recently proposed theory of gravity, the so-called Horava-Lifshitz gravity, which provides a way to make the theory power counting renormalizable by breaking Lorentz invariance. It is showed that dark energy can be well explained in the frame of this extension, just in terms of gravity. It is also explored the possibility to unify inflation and late-time acceleration under the same mechanism, providing a natural explanation the accelerated expansion.Comment: 4 pages. Contribution to the Proceedings of the Spanish Relativity Meeting (ERE) 2010, Granada, Spai

Segregation-induced grain boundary electrical potential in ionic oxide materials: A first principles model

A first principles continuum analytical model for cationic segregation to the grain boundaries in complex ceramic oxides is presented. The model permits one to determine the electric charge density and the segregation-induced electric potential profiles through the grain and can be extrapolated to the range of nanostructured grain sizes. The theoretical predictions are compared with existing data for yttria-stabilized tetragonal zirconia polycrystals. The implications for physical properties (mainly high temperature plasticity and hardening behaviour) are then discussed.Gobierno de España MAT2009-14351-C02-01, MAT2009-14351-C02-0

Unprecedented layered coordination polymers of dithiolene group 10 metals: Magnetic and electrical properties

One-pot reactions between Ni(ii), Pd(ii) or Pt(ii) salts and 3,6-dichloro-1,2-benzenedithiol (HSC6H2Cl2SH) in KOH medium under argon lead to a series of bis-dithiolene coordination polymers. X-ray analysis shows the presence of a common square planar complex [M(SC6H2Cl2S)2]2- linked to potassium cations forming either a two-dimensional coordination polymer network for {[K2(μ-H2O)2(μ-thf)(thf)2][M(SC6H2Cl2S)2]}n [M = Ni (1) and Pd (2)] or a one-dimensional coordination polymer for {[K2(μ-H2O)2(thf)6][Pt(SC6H2Cl2S)2]}n (3). In 3 the coordination environment of the potassium ions may slightly change leading to the two-dimensional coordination polymer {[K2(μ-H2O)(μ-thf)2][Pt(SC6H2Cl2S)2]}n (4) that crystallizes together with 3. The physical characterization of compounds 1-3 show similar trends, they are diamagnetic and behave as semiconductorsWe thank financial support from MICINN (MAT2013-46753-C2-1-P, CTQ2014-52758-P and MAT2014-56143-R) and Generalitat Valenciana (PrometeoII/2014/076

Shadows and photon rings of regular black holes and geonic horizonless compact objects

The optical appearance of a body compact enough to feature an unstable bound orbit, when surrounded by an accretion disk, is expected to be dominated by a luminous ring of radiation enclosing a central brightness depression typically known as the shadow. Despite observational limitations, the rough details of this picture have been now confirmed by the results of the EHT Collaboration on the imaging of the M87 and Milky Way supermassive central objects. However, the precise characterization of both features - ring and shadow - depends on the interaction between the background geometry and the accretion disk, thus being a fertile playground to test our theories on the nature of compact objects and the gravitational field itself in the strong-field regime. In this work we use both features in order to test a continuous family of solutions interpolating between regular black holes and horizonless compact objects, which arise within the Eddington-inspired Born-Infeld theory of gravity, a viable extension of Einstein's General Relativity (GR). To this end we consider seven distinctive classes of such configurations (five black holes and two traversable wormholes) and study their optical appearances under illumination by a geometrically and optically thin accretion disk, emitting monochromatically with three analytic intensity profiles previously suggested in the literature. We build such images and consider the sub-ring structure created by light rays crossing the disk more than once and existing on top of the main ring of radiation. We discuss in detail the modifications as compared to their GR counterparts, the Lyapunov exponents of unstable nearly-bound orbits, as well as the differences between black hole and traversable wormholes for the three intensity profiles.Comment: 25 pages, 53 individual figures; v2: many modifications and additions, changes to the styles of figures, new tables; version accepted for publication on Class. Quant. Grav special issue"CQG - Focus issue on Quantum Gravity Phenomenology in the Multi-Messenger Era: Challenges and Perspectives extension

Ejes para delinear un pensamiento crítico latinoamericano

El presente trabajo es un paso más de un camino, siempre inacabado, que comenzó como una necesidad docente. Cuando en los cursos de teoría general, introducción o filosofía del derecho, terminaba de presentar los paradigmas tradicionales –iusnaturalismo y positivismo- me resultaba complejo explicar en pocas clases los distintos senderos en que se había desarrollado el pensamiento jurídico a partir de mediados del siglo XX. Así comencé a elaborar una suerte de matriz de análisis que, cuatrimestre tras cuatrimestre, fue incorporando nuevas categorías, hasta alcanzar diez dicotomías que permitieran distinguir dos grandes perspectivas postpositivistas, a las que llamé liberales y críticas. [Extracto a modo de resumen]Facultad de Ciencias Jurídicas y Sociale

The False Dichotomy between Guarantee-Constitutionalism and Judicial Activism

El surgimiento de diversas corrientes post-positivistas, particularmente aquellas denominadas neo-constitucionalistas, han puesto en el centro de la escena iusfilosófica la supuesta tensión entre el respeto de las garantías constitucionales y el activismo judicial. El presente trabajo intenta mostrar cómo —particularmente en el ámbito de los países de América Latina— no solo se trata de una falsa dicotomía, sino que en muchos casos solo es posible garantizar la protección de los derechos fundamentales —en especial los económicos, sociales y culturales— mediante prácticas judiciales proactivas.The emergence of different post-positivist theories of law, particularly those called neoconstitutionalists, have placed at the center of the philosophical scene the alleged tension between respect for constitutional guarantees and judicial activism. This paper tries to show how, particularly in the Latin American countries, it is not only a false dichotomy, but in many cases those proactive judicial practices are the only possible way to guarantee the protection of fundamental rights —especially economic, social and political rights—

Correlation functions in scalar field theory at large charge

We compute general higher-point functions in the sector of large charge operators ϕn,ϕ¯¯¯n at large charge in O(2) (ϕ¯¯¯ϕ)2 theory. We find that there is a special class of "extremal" correlators having only one insertion of ϕ¯¯¯n that have a remarkably simple form in the double-scaling limit n →∞ at fixed g n2 ≡ λ, where g ~ ϵ is the coupling at the O(2) Wilson-Fisher fixed point in 4 − ϵ dimensions. In this limit, also non-extremal correlators can be computed. As an example, we give the complete formula for ⟨ϕ(x1)nϕ(x2)nϕ¯¯¯(x3)nϕ¯¯¯(x4)n⟩, which reveals an interesting structure

Recent Advances in Asymmetric Organocatalyzed Conjugate Additions to Nitroalkenes

The asymmetric conjugate addition of carbon and heteroatom nucleophiles to nitroalkenes is a very interesting tool for the construction of highly functionalized synthetic building blocks. Thanks to the rapid development of asymmetric organocatalysis, significant progress has been made during the last years in achieving efficiently this process, concerning chiral organocatalysts, substrates and reaction conditions. This review surveys the advances in asymmetric organocatalytic conjugate addition reactions to α,β-unsaturated nitroalkenes developed between 2013 and early 2017.We thank the financial support from the Spanish Ministerio de Economía, Industria y Competitividad (CTQ2015-66624-P) and the University of Alicante (UAUSTI16-03, AUSTI16-10, VIGROB-173, VIGROB-285)

Pseudoartrosis del cóndilo humeral en niños

La pseudoartrosis del cóndilo humeral en niños es una complicación que ocurre con una frecuencia del 14% a pesar de un tratamiento adecuado de la fractura. El presente estudio evalúa dos casos de pseudoartrosis del cóndilo humeral en fracturas tipo I y II de Milch en dos niños de 12 y 7 años respectivamente. En la fractura tipo I el tratamiento realizado consistió en osteosíntesis a compresión interponiendo un injerto de ala ilíaca en el foco. La consolidación y desaparición de la sintomatología se obtuvo a los tres meses. En la fractura tipo II se efectuó una osteosíntesis a compresión sin aporte de injerto, con consolidación del foco 10 meses después. En ninguno de los dos casos se observó alteración del crecimiento óseo. En conclusión, los casos de fracturas completas con mínimo desplazamiento el tratamiento aconsejable sería la osteosíntesis percutánea. En caso de pseudoartrosis estaría indicado el tratamiento quirúrgico, siendo suficiente la fijación a compresión colocando un puente de injerto óseo, siendo de fundamental importancia la correcta reducción de los fragmentos óseos.Pseudoarthrosis of the lateral humeral condyle is a complication occurring in 14% of the fractures in children despite an adequate initial management. The present study ilustrates two cases of such a condition after a Milch type I and type II fractures in two girls 12 and 7 year-old respectively. Internal fixation of the pseudoarthrosis was done in bowth cases. The type I fractures was treated by fixation with two maleollar screws and bone grafting, while type II fracture was managed by resection of the interposed fibrous tissue and screw fixation. Consolidation was achieved at three and 10 months respectively. There were no adverse effects observed in the physeal growth. In conclusion, in minimaly displaced complete fractures, percutaneous fixation would be the treatment of choice. Internal fixation with compression screws would be advised when pseudoarthrosis is stablished

A first experimental evidence by transmission electron microscopy of dislocation disociation in the TeO2 system

En este trabajo se pretende analizar la microestructura de monocristales de TeO2 (paratelurita) deformados plásticamente en compresión uniaxial a alta temperatura (∼870 K) en distintas condiciones. Para ello, se han ensayado muestras con orientación cristalográfica [110], y se han cortado láminas correspondientes a los planos de deslizamiento para ser observadas con microscopía electrónica de transmisión. El estudio de la subestructura de dislocaciones en este material es complejo debido a su alta anisotropía. La observación de dicha microestructura ha puesto de manifiesto la presencia de disociación de dislocaciones. Es la primera vez que se encuentra este fenómeno en la paratelurita. De la distancia de equilibrio entre dislocaciones parciales, se ha podido obtener una estimación de la energía de falta de apilamiento en este sistema.This work intends to analyse the microstructure of paratellurite (TeO2 single crystals) plastically deformed at high temperature ∼870 K) in uniaxial compression along [110]. Samples have been mechanically tested, and thin foils have been cut from them, corresponding to the slip systems to be observed in transmission electron microscopy. The study of the dislocation substructure in this material is rather complex due to its high anisotropy. Microstructural observation by TEM has put into evidence the presence of dislocation dissociation. This is the first work reporting this fact. From the equilibrium distance between partials, an estimation of the stacking fault energy has been carried out