A complete gauge-invariant formalism for arbitrary second-order perturbations of a Schwarzschild black hole

Using recently developed efficient symbolic manipulations tools, we present a general gauge-invariant formalism to study arbitrary radiative $(l\geq 2)$ second-order perturbations of a Schwarzschild black hole. In particular, we construct the second order Zerilli and Regge-Wheeler equations under the presence of any two first-order modes, reconstruct the perturbed metric in terms of the master scalars, and compute the radiated energy at null infinity. The results of this paper enable systematic studies of generic second order perturbations of the Schwarzschild spacetime. In particular, studies of mode-mode coupling and non-linear effects in gravitational radiation, the second-order stability of the Schwarzschild spacetime, or the geometry of the black hole horizon.Comment: 14 page

Secadero tendalero con chimenea solar

El secado solar de frutas y hortalizas está siendo utilizado en distintos lugares del mundo y particularmente en Argentina. Si bien existen numerosos diseños de distinta complejidad, se presentan algunos problemas que requieren atención y estudio, especialmente en lo que se refiere a la tecnología de secaderos en convección natural. En el presente trabajo se detallan los aspectos constructivos de un tendalero adaptado para funcionar como secadero solar pasivo con una chimenea solar incorporada. El sistema básicamente consiste de un colector solar, cámara de secado y chimenea. Para el modelo de simulación se utilizó el SIMUSOL. Se analiza el sistema térmicamente y los resultados del ajuste de la simulación. Se muestran los resultados de los ensayos realizados: secado de pimiento para pimentón y membrillos. La simulación permitió determinar el flujo másico de aire dentro del secadero y resultó ser una herramienta útil a la hora del diseño. Los productos obtenidos son de buena calidad y el tiempo de secado se considera razonable para este tipo de secadero.Solar drying of fruits and vegetables is being used worldwide and particularly in Argentina. Although there are numerous designs of different complexity, they present some problems that require attention and study, especially when natural convection driers are used. This paper describes building aspects of a “tendalero” adapted for working as a passive solar drier with an incorporated solar chimney. The system essentially consists of a solar collector, a drying unit and a chimney. The simulation model used was SIMUSOL. A thermal analysis of the system is done and the results of adjustment simulation are considered. The results of the assays carried out, pepper for paprika and quince, are also shown. The simulation allowed to determine the mass flow rate of air inside the drier, and proved to be an important tool for design. The quality of dried products is good and the drying time is considered reasonable for this type of driers.Fil: Iriarte, Adolfo Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigaciones en Energía no Convencional; Argentina. Universidad Nacional de Catamarca. Facultad de Ciencias Agrarias; ArgentinaFil: Bistoni, S.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigaciones en Energía no Convencional; Argentina. Universidad Nacional de Catamarca. Facultad de Ciencias Agrarias; ArgentinaFil: Luque, V.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigaciones en Energía no Convencional; Argentina. Universidad Nacional de Catamarca. Facultad de Ciencias Agrarias; ArgentinaFil: Lara, M.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigaciones en Energía no Convencional; Argentina. Universidad Nacional de Catamarca. Facultad de Ciencias Agrarias; ArgentinaFil: Brizuela, L.. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Salta. Instituto de Investigaciones en Energía no Convencional; Argentina. Universidad Nacional de Catamarca. Facultad de Ciencias Agrarias; Argentin

Applying and validating the PTVA-3 Model at the Aeolian Islands, Italy: assessment of the vulnerability of buildings to tsunamis

The volcanic archipelago of the Aeolian Islands (Sicily, Italy) is included on the UNESCO World Heritage list and is visited by more than 200 000 tourists per year. Due to its geological characteristics, the risk related to volcanic and seismic activity is particularly high. Since 1916 the archipelago has been hit by eight local tsunamis. The most recent and intense of these events happened on 30 December 2002. It was triggered by two successive landslides along the north-western side of the Stromboli volcano (Sciara del Fuoco), which poured approximately 2–3×10<sup>7</sup> m<sup>3</sup> of rocks and debris into the Tyrrhenian Sea. The waves impacted across the whole archipelago, but most of the damage to buildings and infrastructures occurred on the islands of Stromboli (maximum run-up 11 m) and Panarea. <br><br> The aim of this study is to assess the vulnerability of buildings to damage from tsunamis located within the same area inundated by the 2002 event. The assessment is carried out by using the PTVA-3 Model (Papathoma Tsunami Vulnerability Assessment, version 3). The PTVA-3 Model calculates a Relative Vulnerability Index (RVI) for every building, based on a set of selected physical and structural attributes. Run-up values within the area inundated by the 2002 tsunami were measured and mapped by the Istituto Italiano di Geofisica e Vulcanologia (INGV) and the University of Bologna during field surveys in January 2003. Results of the assessment show that if the same tsunami were to occur today, 54 buildings would be affected in Stromboli, and 5 in Panarea. The overall vulnerability level obtained in this analysis for Stromboli and Panarea are "average"/"low" and "very low", respectively. Nonetheless, 14 buildings in Stromboli are classified as having a "high" or "average" vulnerability. For some buildings, we were able to validate the RVI scores calculated by the PTVA-3 Model through a qualitative comparison with photographs taken by INGV and the University of Bologna during the post-tsunami survey. With the exception of a single structure, which is partially covered by a coastal dune on the seaward side, we found a good degree of accuracy between the PTVA-3 Model forecast assessments and the actual degree of damage experienced by buildings. This validation of the model increases our confidence in its predictive capability. Given the high tsunami risk for the archipelago, our results provide a framework for prioritising investments in prevention measures and addressing the most relevant vulnerability issues of the built environment, particularly on the island of Stromboli

Influence of orthodontic treatment on temporomandibular disorders: a systematic review

Objectives: The aim of this literature systematic review was to evaluate the possible association between malocclusions, orthodontic treatment and development of temporomandibular disorders. Material and Methods: A search was carried out on PubMed-Medline database from January 2000 to August 2013 using the keywords “ orthodontics and temporomandibular disorders ”, “ orthodontics and facial pain ” and “ malocclusion and temporomandibular disorders ”. Human studies included in the study were those assessing signs and symptoms of temporomandibular disorders in relation to orthodontic treatment. Results: The search strategy resulted in 61 articles. After selection according to the inclusion/exclusion criteria 9 articles qualified for the final analysis. The articles which linked orthodontics and development of temporomandibular disorders showed very discrepant results. Some indicated that orthodontic treatment could improve signs and symptoms of temporomandibular disorders, but none of them obtained statistically significant dif ferences. Conclusions: According to the authors examined, there is no evidence for a cause-effect relationship between orthodontic treatment and temporomandibular disorders, or that such treatment might improve or prevent them. More longitudinal studies are needed to verify any possible interrelationshi

XUV digital in-line holography using high-order harmonics

A step towards a successful implementation of timeresolved digital in-line holography with extreme ultraviolet radiation is presented. Ultrashort XUV pulses are produced as high-order harmonics of a femtosecond laser and a Schwarzschild objective is used to focus harmonic radiation at 38 nm and to produce a strongly divergent reference beam for holographic recording. Experimental holograms of thin wires are recorded and the objects reconstructed. Descriptions of the simulation and reconstruction theory and algorithms are also given. Spatial resolution of few hundreds of nm is potentially achievable, and micrometer resolution range is demonstrated.Comment: 8 pages, 8 figure

Loop Quantum Gravity and the The Planck Regime of Cosmology

The very early universe provides the best arena we currently have to test quantum gravity theories. The success of the inflationary paradigm in accounting for the observed inhomogeneities in the cosmic microwave background already illustrates this point to a certain extent because the paradigm is based on quantum field theory on the curved cosmological space-times. However, this analysis excludes the Planck era because the background space-time satisfies Einstein's equations all the way back to the big bang singularity. Using techniques from loop quantum gravity, the paradigm has now been extended to a self-consistent theory from the Planck regime to the onset of inflation, covering some 11 orders of magnitude in curvature. In addition, for a narrow window of initial conditions, there are departures from the standard paradigm, with novel effects, such as a modification of the consistency relation involving the scalar and tensor power spectra and a new source for non-Gaussianities. Thus, the genesis of the large scale structure of the universe can be traced back to quantum gravity fluctuations \emph{in the Planck regime}. This report provides a bird's eye view of these developments for the general relativity community.Comment: 23 pages, 4 figures. Plenary talk at the Conference: Relativity and Gravitation: 100 Years after Einstein in Prague. To appear in the Proceedings to be published by Edition Open Access. Summarizes results that appeared in journal articles [2-13

Numerical loop quantum cosmology: an overview

A brief review of various numerical techniques used in loop quantum cosmology and results is presented. These include the way extensive numerical simulations shed insights on the resolution of classical singularities, resulting in the key prediction of the bounce at the Planck scale in different models, and the numerical methods used to analyze the properties of the quantum difference operator and the von Neumann stability issues. Using the quantization of a massless scalar field in an isotropic spacetime as a template, an attempt is made to highlight the complementarity of different methods to gain understanding of the new physics emerging from the quantum theory. Open directions which need to be explored with more refined numerical methods are discussed.Comment: 33 Pages, 4 figures. Invited contribution to appear in Classical and Quantum Gravity special issue on Non-Astrophysical Numerical Relativit