1,263 research outputs found
Black hole thermodynamics, conformal couplings, and R-2 terms
Lovelock theory provides a tractable model of higher-curvature gravity in which several questions can be studied analytically. This is the reason why, in the last years, this theory has become the favorite arena to study the effects of higher-curvature terms in the context of AdS/CFT correspondence. Lovelock theory also admits extensions that permit to accommodate matter coupled to gravity in a non-minimal way. In this setup, problems such as the backreaction of matter on the black hole geometry can also be solved exactly. In this paper, we study the thermodynamics of black holes in theories of gravity of this type, which include both higher-curvature terms, U(1) gauge fields, and conformal couplings with matter fields in D dimensions. These charged black hole solutions exhibit a backreacting scalar field configuration that is regular everywhere outside and on the horizon, and may exist both in asymptotically flat and asymptotically Anti-de Sitter (AdS) spaces. We work out explicitly the boundary action for this theory, which renders the variational problem well-posed and suffices to regularize the Euclidean action in AdS. We also discuss several interrelated properties of the theory, such as its duality symmetry under field redefinition and how it acts on black holes and gravitational wave solutions.</p
Análisis de la progresión del daño macroscópico en la interfase menisco-sutura tras reparación de la raíz: estudio biomecánico en modelo porcino
En un modelo porcino de la reparación de la raíz posterior del menisco medial sometido a cargas cíclicas representativas de protocolos de rehabilitación habituales en el post-operatorio temprano, no se observa daño macroscópico en la interfase tejido-sutura generada por el orificio de sutura. El desgarro meniscal en ensayo de tracción a rotura se inicia a valores de carga muy superiores a los esperables en el posoperatorio.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech
Eternity and the cosmological constant
The purpose of this paper is to analyze the stability of interacting matter
in the presence of a cosmological constant. Using an approach based on the heat
equation, no imaginary part is found for the effective potential in the
presence of a fixed background, which is the n-dimensional sphere or else an
analytical continuation thereof, which is explored in some detail.Comment: 45 pages, 6 figure
Enteroviruses in Spain: virological and epidemiological studies over 10 years (1988-97)
A total of 15,662 clinical samples were analysed for enterovirus (EV) isolation in cell cultures during a 10-year period (1988-97). Furthermore, 210 isolates of EV obtained in primary laboratories within Spain from patients with meningitis were characterized. The total number of EV typed was 758, including 727 non-polio EV and 31 Sabin-like (SL) polioviruses. Twenty-eight EV serotypes were represented. Echoviruses comprised 90% (653/727) of fully typed non-polio EV. The four most prevalent serotypes were echovirus 30, echovirus 9, echovirus 6 and echovirus 4. Echovirus 30 was the main serotype associated with meningitis. Echovirus 9 was the aetiological agent in 20 outbreaks of meningitis while the occurrence of echovirus 6 was localized in 1 year (1997). Coxsackieviruses A and B occurred in 3 and 7% of the non-polio EV respectively. Coxsackievirus B5 presented the relative greater abundance. This paper examines the epidemiology of EV in Spain to serotype level over a 10-year period with special attention to non-polio EV associated with meningitis.Dr I. Casas is a postdoctoral fellow supported by the Institute de Salud Carlos III, Becas de Perfeccionamiento (97/4165). We acknowledge the assistance provided by clinical colleagues in other virology laboratories: Gurutze Rubio (Cruces, Bilbao, Hospital), Nuria Rabella (Santa Cruz y San Pablo, Barcelona Hospital), Joaquin Otero (Doce de Octubre, Madrid Hospital). We also thank Raquel Noguerol, Hortensia del Pozo and Isidoro Bustillo for their technical assistance and an anonymous referee for many useful suggestions. This work was partially supported by Fondo de Investigación Sanitaria grant FIS 96/0304.S
Recent increase in species-wide diversity after interspecies introgression in the highly endangered Iberian lynx
Genetic diversity is lost in small and isolated populations, affecting many globally declining species. Interspecific admixture events can increase genetic variation in the recipient species’ gene pool, but empirical examples of species-wide restoration of genetic diversity by admixture are lacking. Here we present multi-fold coverage genomic data from three ancient Iberian lynx (Lynx pardinus) approximately 2,000–4,000 years old and show a continuous or recurrent process of interspecies admixture with the Eurasian lynx (Lynx lynx) that increased modern Iberian lynx genetic diversity above that occurring millennia ago despite its recent demographic decline. Our results add to the accumulating evidence for natural admixture and introgression among closely related species and show that this can result in an increase of species-wide genetic diversity in highly genetically eroded species. The strict avoidance of interspecific sources in current genetic restoration measures needs to be carefully reconsidered, particularly in cases where no conspecific source population exists
Self-control in Sparsely Coded Networks
A complete self-control mechanism is proposed in the dynamics of neural
networks through the introduction of a time-dependent threshold, determined in
function of both the noise and the pattern activity in the network. Especially
for sparsely coded models this mechanism is shown to considerably improve the
storage capacity, the basins of attraction and the mutual information content
of the network.Comment: 4 pages, 6 Postscript figure
Comorbid autoimmune diseases and burden of diabetes-related complications in patients with type 1 diabetes from a Mediterranean area
AIM: To assess the prevalence of autoimmune diseases (AID) in patients with type 1 diabetes (T1D) and to evaluate whether the rate of diabetes-related complications differs depending on the presence of AID. METHODS: Cross-sectional analysis of 13,570 T1D patients aged ≥ 18 years registered in the SIDIAP database. The association between AID and diabetes-related complications was assessed by multivariable logistic regression models. RESULTS: The prevalence of AID was 18.3% with thyroid AID being the most common. Patients with T1D and AID were more often female and their current age, age of diabetes onset and diabetes duration were higher. Patients with only thyroid AID experienced a lower risk of peripheral artery disease (odds ratio [OR] = 0.51, 95%; confidence interval [CI] 0.31 to 0.81) and kidney disease (OR = 0.68, 95%; 95% CI 0.54 to 0.85), whereas patients with other AID had an increased risk of ischemic heart disease (OR = 1.48, 95%; 95% CI 1.04 to 2.06). CONCLUSIONS: The burden of diabetes-related complications in patients with T1D differs according to the type of additional AID. The presence of diabetes complications is lower in those with autoimmune thyroid disease while the presence of other AID is associated with higher rates of ischemic heart disease
Comparison of retinal nerve fiber layer thinning and retinal ganglion cell loss after optic nerve transection in adult albino rats
We compared the time-course and magnitude of retinal nerve fiber layer (RNFL) thinning with that of retinal ganglion cell (RGC) loss after intraorbital optic nerve transection (IONT) in adult rats
Correlations of the stress-energy tensor in AdS spaces via the generalized zeta-function method
We calculate the vacuum expectation values of the stress-energy bitensor of a
minimally coupled massless scalar field in anti-de Sitter (AdS) spaces. These
correlators, also known as the noise kernel, act as sources in the
Einstein-Langevin equations of stochastic gravity [1,2] which govern the
induced metric fluctuations beyond the mean-field dynamics described by the
semiclassical Einstein equations of semiclassical gravity. Because the AdS
spaces are maximally symmetric the eigenmodes have analytic expressions which
facilitate the computation of the zeta-function [3,4]. Upon taking the second
functional variation of the generalized zeta function introduced in [5] we
obtain the correlators of the stress tensor. Both the short and the long
geodesic distance limits of the correlators are presented.Comment: 12 pages, no figures. Presented at IARD 2010 Conference, Hualien,
Taiwan (May 2010). Proceedings to appear in Journal of Physics: Conference
Serie
Teletrabajo y condiciones de trabajo durante la crisis COVID-19
Se aborda un estudio de la modalidad de trabajo a distancia o "teletrabajo", la cual se ha convertido en un aspecto muy importante de la actividad laboral actual a causa de la pandemia de la COVID-19, que ha sumido al mundo en una crisis sanitaria sin precedente. <br /
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