Quasinormal modes of D-dimensional de Sitter spacetime

We calculate the exact values of the quasinormal frequencies for an electromagnetic field and a gravitational perturbation moving in $D$-dimensional de Sitter spacetime ($D \geq 4$). We also study the quasinormal modes of a real massive scalar field and we compare our results with those of other references.Comment: 26 pages, 1 table. Some changes made according to referee's suggestions. Matches published version in GR

Electromagnetic quasinormal modes of D-dimensional black holes II

By using the sixth order WKB approximation we calculate for an electromagnetic field propagating in D-dimensional Schwarzschild and Schwarzschild de Sitter black holes its quasinormal frequencies for the fundamental mode and first overtones. We study the dependence of these QN frequencies on the value of the cosmological constant and the spacetime dimension. We also compare with the known results for the gravitational perturbations propagating in the same background. Moreover we exactly compute the QN frequencies of the electromagnetic field propagating in D-dimensional massless topological black hole and for charged D-dimensional Nariai spacetime we exactly calculate the QN frequencies of the coupled electromagnetic and gravitational perturbations.Comment: 34 pages, 14 figures, 6 table

Bone loss in implants placed at subcrestal and crestal level: A systematic review and meta-analysis

Background: To assess differences in marginal bone loss in implants placed at subcrestal versus crestal level. Methods: An electronic and a manual research of articles written in English from Jaunary 2010 to January 2018 was performed by two independent reviewers. Clinical trials comparing bone loss for implants placed at crestal and subcrestal level were included. Pooled estimates from comparable studies were analyzed using a continuous random-effects model meta-analysis with the objective of assessing differences in crestal bone loss between the two vertical positions. Results: 16 studies were included; 10 studies did not encounter statistically significant differences between the two groups with respect to bone loss. Three articles found greater bone loss in subcrestal implants; while 3 found more bone loss in crestal implants. A meta-analysis for randomized control trial (RCT) studies reported an average and non-statistically different crestal bone loss of 0.028 mm. Conclusions: A high survival rate and a comparable bone loss was obtained both for crestal and subcrestal implants’ placement. Quantitative analysis considering a homogenous sample confirms that both vertical positions are equally valid in terms of perimplant bone loss. However, with respect to soft tissue; in presence of a thin tissue; a subcrestal placement of the implant should be preferred as it may reduce the probability for the implant to become exposed in the future and thus avoid the risk of suffering from peri-implant pathologies

Converging shocks in elastic-plastic solids

We present an approximate description of the behavior of an elastic-plastic material processed by a cylindrically or spherically symmetric converging shock, following Whitham's shock dynamics theory. Originally applied with success to various gas dynamics problems, this theory is presently derived for solid media, in both elastic and plastic regimes. The exact solutions of the shock dynamics equations obtained reproduce well the results obtained by high-resolution numerical simulations. The examined constitutive laws share a compressible neo-Hookean structure for the internal energy e = e_(s)(I_1)+e_(h)(ρ,ς), where e_(s) accounts for shear through the first invariant of the Cauchy–Green tensor, and e_(h) represents the hydrostatic contribution as a function of the density ρ and entropy ς. In the strong-shock limit, reached as the shock approaches the axis or origin r=0, we show that compression effects are dominant over shear deformations. For an isothermal constitutive law, i.e., e_(h) = e_(h)(ρ), with a power-law dependence e_(h) ∝ ρ_(α), shock dynamics predicts that for a converging shock located at r=R(t) at time t, the Mach number increases as M ∝ [log(1/R)]^α, independently of the space index s, where s=2 in cylindrical geometry and 3 in spherical geometry. An alternative isothermal constitutive law with p(ρ) of the arctanh type, which enforces a finite density in the strong-shock limit, leads to M ∝ R^(−(s−1)) for strong shocks. A nonisothermal constitutive law, whose hydrostatic part eh is that of an ideal gas, is also tested, recovering the strong-shock limit M∝R^(−(s−1)/n(γ)) originally derived by Whitham for perfect gases, where γ is inherently related to the maximum compression ratio that the material can reach, (γ+1)/(γ−1). From these strong-shock limits, we also estimate analytically the density, radial velocity, pressure, and sound speed immediately behind the shock. While the hydrostatic part of the energy essentially commands the strong-shock behavior, the shear modulus and yield stress modify the compression ratio and velocity of the shock far from the axis or origin. A characterization of the elastic-plastic transition in converging shocks, which involves an elastic precursor and a plastic compression region, is finally exposed

Rpd3L and Hda1 histone deacetylases facilitate repair of broken forks by promoting sister chromatid cohesion

Genome stability involves accurate replication and DNA repair. Broken replication forks, such as those encountering a nick, lead to double strand breaks (DSBs), which are preferentially repaired by sister-chromatid recombination (SCR). To decipher the role of chromatin in eukaryotic DSB repair, here we analyze a collection of yeast chromatin-modifying mutants using a previously developed system for the molecular analysis of repair of replication-born DSBs by SCR based on a mini-HO site. We confirm the candidates through FLP-based systems based on a mutated version of the FLP flipase that causes nicks on either the leading or lagging DNA strands. We demonstrate that Rpd3L and Hda1 histone deacetylase (HDAC) complexes contribute to the repair of replication-born DSBs by facilitating cohesin loading, with no effect on other types of homology-dependent repair, thus preventing genome instability. We conclude that histone deacetylation favors general sister chromatid cohesion as a necessary step in SCR

El Consejo Supremo de Aragón y la supervisión de la justicia del reino aragonés durante el siglo XVII

Margarita Ortega se sirve, en el siguiente artículo, de la revisió de los diferentes mecanismos mediante los cuales el Consejo de Aragbn vigilaba los diversos tribunales de justicia del reino aragonés, para determinar en qué manera el Consejo Supremo de Aragón ejercía un efectivo control sobre todo el sistema de justicia del reino de Aragón durante el siglo XVII.Margarita Ortega utilizes in that article the revision of the different mechanism used by the Consejo de Aragón in order to determinate how the Consejo Supremo de Aragbn exercised un effective control over the justice system of Aragón during XVIIth Century

La incidencia de diabetes en Almeria

La Diabetes Mellitus se caracteriza por cifras elevadas de glucemia, originadas por deficiencia en la producción de insulina y/o resistencia a su acción. Se trata de un problema de gran trascendencia. Por un lado, se ha descrito que una parte importante de la población está afectada, y que tanto la incidencia como la prevalencia de diabetes se están incrementando en el mundo. Por otra parte, durante el transcurso de esta enfermedad pueden originarse una serie de complicaciones, incluidas la enfermedad cardiovascular, el ictus, la ceguera, los problemas renales y la amputación del pie o la pierna. Asimismo, puede ser causa de complicaciones en los embarazos, tanto para la madre como para el feto o recién nacido. Los cambios en el estilo de vida de las personas, con un predominio del sedentarismo y una elevada ingesta calórica, están modificando la incidencia y la prevalencia de la Diabetes Mellitus, independientemente de la localización geográfica. Sobre todo la diabetes Mellitus tipo 2 El objetivo de este trabajo es evaluar la incidencia de la diabetes Mellitus en la provincia de Almería, mediante la recogida de datos a través de una encuesta realizada a los pacientes con diabetes Mellitus en las diferentes zonas de Almería. En dicha encuesta se ha tenido en cuenta: el tipo de diabetes, la edad y el sexo de los pacientes, el tiempo que llevan con la enfermedad, el índice de glucosa en sangre del último control, el tipo de medicación que toman, el estrato social al que pertenecen, si han recibido la educación diabetológico, zona geográfica a la que pertenecen, la adherencia al tratamiento y si siguen las recomendaciones de dieta y ejercicio

Realidad y representación en la iconografía de las mujeres españolas de los siglos XVI y XVII

Actas del Décimo Coloquio Internacional de la Asociación Española de Investigación de Historia de las Mujeres (AEIHM) celebrado del 17 al 19 de abril de 2002 en la Universidad Carlos III de MadridPublicad