The Chrono-geometrical Structure of Special and General Relativity: a Re-Visitation of Canonical Geometrodynamics

A modern re-visitation of the consequences of the lack of an intrinsic notion of instantaneous 3-space in relativistic theories leads to a reformulation of their kinematical basis emphasizing the role of non-inertial frames centered on an arbitrary accelerated observer. In special relativity the exigence of predictability implies the adoption of the 3+1 point of view, which leads to a well posed initial value problem for field equations in a framework where the change of the convention of synchronization of distant clocks is realized by means of a gauge transformation. This point of view is also at the heart of the canonical approach to metric and tetrad gravity in globally hyperbolic asymptotically flat space-times, where the use of Shanmugadhasan canonical transformations allows the separation of the physical degrees of freedom of the gravitational field (the tidal effects) from the arbitrary gauge variables. Since a global vision of the equivalence principle implies that only global non-inertial frames can exist in general relativity, the gauge variables are naturally interpreted as generalized relativistic inertial effects, which have to be fixed to get a deterministic evolution in a given non-inertial frame. As a consequence, in each Einstein's space-time in this class the whole chrono-geometrical structure, including also the clock synchronization convention, is dynamically determined and a new approach to the Hole Argument leads to the conclusion that "gravitational field" and "space-time" are two faces of the same entity. This view allows to get a classical scenario for the unification of the four interactions in a scheme suited to the description of the solar system or our galaxy with a deperametrization to special relativity and the subsequent possibility to take the non-relativistic limit.Comment: 33 pages, Lectures given at the 42nd Karpacz Winter School of Theoretical Physics, "Current Mathematical Topics in Gravitation and Cosmology", Ladek, Poland, 6-11 February 200

Espectro polínico de la franja litoral en la provincia de Granada: periodo estudiado 2003-2005

XV lnternational A.P.L.E. Symposium of Palynolog

Estudio de la actividad alergénica de Olea europaea L. y su relación con ingresos de pacientes en los Servicios de Urgencias (Hospital San Cecilio de Granada)

XV lnternational A.P.L.E. Symposium of Palynolog

Enhancement of Hydrolysis through the Formation of Mixed Heterometal Species: Al3+/CH3Sn3+ Mixtures

ABSTRACT: The hydrolysis of mixed-metal cations (Al3+/CH3Sn3+) was studied in aqueous solutions of NaNO3, at I = 1.00 ± 0.05 mol·dm−3 and T = 298.15 K, by potentiometric technique. Several hydrolytic mixed species are formed in this mixed system, namely, Alp(CH3Sn)q(OH)r with (p, q, r) = (1, 1, 4), (1, 1, 5), (1, 1, 6), (2, 1, 4), (1, 2, 5), (1, 4, 11), (1, 3, 8), and (7, 6, 32). The stability of these species, expressed by the equilibrium: pAl3+ + qCH3Sn3+ + rOH− = Alp(CH3Sn)q(OH)r 3(p+q)−r, βpqr OH, can be modeled by the empirical relationship: log βpqr OH = −3.34 + 2.67p + 9.23(q + r). By using the equilibrium constant Xpqr relative to the formation reaction: pAl(p+q)(OH)r + q(CH3Sn)(p+q)(OH)r = (p + q)Alp(CH3Sn)q(OH)r, it was found that the formation of heterometal mixed species is thermodynamically favored, and the extra stability can be expressed as a function of the difference in the stability of parent homometal species. This leads, in turn, to a significant enhancement of hydrolysis and solubility

Structure of smectic defect cores: an X-ray study of 8CB liquid crystal ultra-thin films

We study the structure of very thin liquid crystal films frustrated by antagonistic anchorings in the smectic phase. In a cylindrical geometry, the structure is dominated by the defects for film thicknesses smaller than 150 nm and the detailed topology of the defects cores can be revealed by x-ray diffraction. They appear to be split in half tube-shaped Rotating Grain Boundaries (RGB). We determine the RGB spatial extension and evaluate its energy per unit line. Both are significantly larger than the ones usually proposed in the literatureComment: 4 page

Foldalign 2.5:multithreaded implementation for pairwise structural RNA alignment

Motivation: Structured RNAs can be hard to search for as they often are not well conserved in their primary structure and are local in their genomic or transcriptomic context. Thus, the need for tools which in particular can make local structural alignments of RNAs is only increasing. Results: To meet the demand for both large-scale screens and hands on analysis through web servers, we present a new multithreaded version of Foldalign. We substantially improve execution time while maintaining all previous functionalities, including carrying out local structural alignments of sequences with low similarity. Furthermore, the improvements allow for comparing longer RNAs and increasing the sequence length. For example, lengths in the range 2000–6000 nucleotides improve execution up to a factor of five. Availability and implementation: The Foldalign software and the web server are available at http://rth.dk/resources/foldalign Contact: [email protected] Supplementary information: Supplementary data are available at Bioinformatics online

Osteochondroma of the mandibular condyle: Resection and reconstruction using vertical sliding osteotomy of the mandibular ramus

Osteochondroma is one of the most common benign bone tumours, although not in the craniofacial region. More than half of these appear in the coronoid process. It can appear on the mandibular condyle, especially in its medial half, and mainly affects women aged around forty years. We present the case of a 51-year-old woman with pain of several months? duration in the right temporomandibular joint (TMJ) and no other symptoms. Panoramic radiography showed an enlarged condyle with no subchondral cysts. Computed tomography showed a bony proliferation with benign signs and a scintigraphy revealed an increased uptake in the condyle. Due to the painful clinical symptoms, a surgical procedure using preauricular and retromandibular approaches was performed to excise the condyle. The resulting defect, which was 9 mm high, was reconstructed by means of a vertical sliding osteotomy of the mandibular ramus and two miniplates for osteosynthesis. Almost two years later, the patient is symptomfree and has a normal opening with no malocclusion or deviation in the opening pattern. We present and discuss different reconstruction options after condylectomy

The miRNA pathway limits AGO1 availability during siRNA-mediated PTGS defense against exogenous RNA

In plants, most microRNAs (miRNAs) and several endogenous small interfering RNAs (siRNAs) bind to ARGONAUTE1 (AGO1) to regulate the expression of endogenous genes through post-transcriptional gene silencing (PTGS). AGO1 also participates in a siRNA-mediated PTGS defense response that thwarts exogenous RNA deriving from viruses and transgenes. Here, we reveal that plants supporting transgene PTGS exhibit increased levels of AGO1 protein. Moreover, increasing AGO1 levels either by mutating miRNA pathway components or, more specifically, by impairing miR168-directed regulation of AGO1 mRNA leads to increased PTGS efficiency, indicating that the miRNA pathway dampens the efficiency of PTGS, likely by limiting the availability of AGO1. We propose that during the transgene PTGS initiation phase, transgene siRNAs and endogenous siRNAs and miRNA compete to bind to AGO1, leading to a transient reduction in AGO1–miR168 complexes and a decline in AGO1 mRNA cleavage. The concomitant increase in AGO1 protein levels would facilitate the formation of AGO1–transgene siRNA complexes and the entry into the PTGS amplification phase. We suggest that the miRNA pathway imposes an important limitation on PTGS efficiency, which could help protect endogenous mRNAs from being routinely targeted by PTGS

Análisis aerobiológico del polen de Cupressaceae en Granada (sureste P. Ibérica): su repercusión en la población atópica

XV lnternational A.P.L.E. Symposium of Palynolog

La primera epístola de Alfonso de Valladolid

Not available.No disponible