Schr\"odinger symmetry of Schwarzschild-(A)dS black hole mechanics

We show that the dynamics of Schwarzschild-(A)dS black holes admit a symmetry under the 2d Schr\"{o}dinger group, whatever the sign or value of the cosmological constant. This is achieved by reformulating the spherically-symmetric reduction of general relativity as a 2d mechanical system with a non-trivial potential controlled by the cosmological constant, and explicitly identifying the conserved charges for black hole mechanics. We expect the Schr\"{o}dinger symmetry to drive the dynamics of quantum Schwarzschild-(A)dS black holes. This suggests that Schr\"{o}dinger-preserving non-linear deformations (of the Gross-Piteavskii type) should capture universal quantum gravity corrections to the black hole geometry. Such scenario could be realized in condensed matter analogue models.Comment: 9 page

Lipschitz operator ideals and the approximation property

[EN] We establish the basics of the theory of Lipschitz operator ideals with the aim of recovering several classes of Lipschitz maps related to absolute summability that have been introduced in the literature in the last years. As an application we extend the notion and main results on the approximation property for Banach spaces to the case of metric spaces. (C) 2015 Elsevier Inc. All rights reserved.P. Rueda acknowledges with thanks the support of the Ministerio de Economia y Competitividad (Spain) MTM2011-22417. E.A. Sanchez Perez acknowledges with thanks the support of the Ministerio de Economia y Competitividad (Spain) MTM2012-36740-C02-02.Achour, D.; Rueda, P.; Sánchez Pérez, EA.; Yahi, R. (2016). Lipschitz operator ideals and the approximation property. Journal of Mathematical Analysis and Applications. 436(1):217-236. https://doi.org/10.1016/j.jmaa.2015.11.050S217236436

Schr\"{o}dinger symmetry in cosmology and black hole mechanics

We show that the (symmetry-reduced) gravitational sectors describing i) the flat FRLW cosmology filled with a massless scalar field and ii) the Schwarzschild black hole mechanics both admit the two dimensional centrally extended Schr\"{o}dinger group as a dynamical symmetry, a symmetry shared by the compressible Navier-Stokes equation. To this end, we use the Eisenhart-Duval (ED) lift method to identify the Schr\"{o}dinger observables. The Casimirs of the observables algebra coincide respectively with the conserved kinetic energy of the scalar field, for cosmology, and with the mass of the black hole, for the Schwarzschild mechanics. Moreover, in both models, the central extension is found to encode the ratio between the IR and UV scales of the gravitational systems. We pursue this analysis by comparing the ED method to the superspace approach and demonstrate their complementarity. We use the superspace approach to show that these two models possess also an infinite dimensional symmetry whose conserved charges organize in two copies of a Witt algebra. Finally, we consider the anisotropic Bianchi I dynamics and show that it admits a dynamical symmetry under the SO$(4,2)$ conformal group, within which one can identify another Schr\"{o}dinger algebra of observables. These new symmetries provide a new way to algebraically characterize these homogeneous gravitational sectors, to guide their quantization or emergence from quantum gravity models, and they suggest new dictionaries with non-linear Schr\"{o}dinger systems and fluid mechanics.Comment: 41+8 page

THEORETICAL APPROACH ON THE STUDY OF TURBULENT WATER FLOW OVER SMOOTH AND L-SHAPED RIBLETS SURFACES

A very important research effort has been developed at many world laboratories these last years in order to reduce the friction drag. For the aircraft and the submarine applications, friction contributes respectively for about 50% and 70% of the total resistance. The use of surface modifications riblets as a means of reducing viscous drag on a body has potential aerodynamic and hydrodynamic applications. In the present study, the theoretical approach allow to determine the velocity field, the wall shear stress, the local skin friction, the boundary layer thickness, the laminar sub layer thickness and the dimensionless drag coefficient. The results found, indicate that the presence of L-shaped riblets surfaces provide changes in the characteristics of the turbulent boundary layer, which are in favor of wall skin friction. Un effort très important a été fourni ces dernières années à travers les laboratoires du monde dans le domaine de la réduction de traînée visqueuse. Pour les avions de transport et les sous marins, la traînée visqueuse contribue respectivement d’environ 50% à 70% de la résistance totale. L’utilisation des modifications au niveau de la surface est un moyen efficace pour réduire la traînée visqueuse dans les applications aérodynamique et hydrodynamique. Dans cette étude, l’approche théorique permis de déterminer le champ de vitesse, la contrainte de cisaillement à la paroi, le coefficient de frottement local, l’épaisseur de la couche limite, l’épaisseur de la sous couche visqueuse et finalement le coefficient non dimensionnel de traînée sont représentés. Les résultats trouvés ont montré que la présence des rainures en lames " L " fournie des changements dans les caractéristiques de la couche limite turbulente, qui sont en faveur du coefficient de frottement pariétal

Hydatid Cyst of the Rib: A New Case and Review of the Literature

The hydatid cyst is not rare in our country, but bone lesions are less common. The disease often takes the appearance of abscess or malignant lesion. We report a case of a 35-year-old man with a hydatid cyst of the rib complicated with cutaneous fistula. The surgery allowed both diagnosis and treatment. Albendazole was then administered to prevent relapse

DYNAMICAL STUDY OF THE FLOW ALONG A TWO-DIMENSIONAL CHANNELWITH A RIGHT ANGLED BEND

A two-dimensional incompressible laminar flow passing through a constant width channel with a ninety-degree turn is investigated. Based on the flow separation and recirculation phenomena downstream of the inner corner , a model profile for the axial velocity component is chosen. Concerning the channel segments upstream and downstream of the previous corner, the insertion of the velocity profiles (incorporating a distortion profile function) in the Navier-Stocks equations and the use of the integral method lead to a linear differential equation for the previous function. Whereas, the corresponding previous differential equation is not linear in the corner region. The analytical and numerical solutions for the first and last equations respectively are obtained and the Reynolds number Re as well as recirculation bubble effects on the flow variables are presented for () 540 Re 100 ≤ ≤ ; the experimental range of flow visualisation and measurement )L'écoulement incompressible, laminaire et bidimensionnel le long d'une conduite coudée à 90° a été étudié. En se basant sur le phénomène de séparation et de recirculation just après le coude, un modèle de profil de la composante de vitesse axiale est choisie. Concerant les deux parties en amant et en aval du coude, l'introduction du profile de vitesse (introduction du profil de la function de deformation) à l'interieur des équations de "Navier Stocks" et l'utilisation de la méthode intégrale menent à une équation différentielle linéaire dont l'inconnue est bien la fonction de déformation. Alors que, l'équation différentielle précédente est non linéaire au niveau du coude. Les solutions analytique et numérique respectivement pour la première et la dernière équation différentièlle sont obtenues. L'effet du nombre de Reynolds aussi bien de la bulle de recirculation sur les variables de l'écoulement est présenté pour 100 Re 540 ≤< (plage expérimentale de mesure et visualization)

Learning lessons from the 2011 Van Earthquake to enhance healthcare surge capacity in Turkey

Historically, Turkey has adopted a reactive approach to natural hazards which resulted in significant losses. However, following the 1999 Kocaeli Earthquake, a more proactive approach has been adopted. This study aims to explore the way this new approach operates on the ground. A multi-national and multi-disciplinary team conducted a field investigation following the 2011 Van Earthquake to identify lessons to inform healthcare emergency planning in Turkey and elsewhere. The team interviewed selected stakeholders including, healthcare emergency responders, search and rescue services, ambulance services, and health authority representatives, in addition to conducting a focus group. Data were analysed according to an open coding process and SWOT analysis. The findings suggest that the approach succeeded in developing a single vision by consolidating official efforts in a more structured way, mobilising many governmental and non-governmental organisations, securing significant amounts of resources including physical and human, and increasing the resilience and flexibility of infrastructure to expand its capacity. However, more attention is required to the development of stronger management procedures and acquisition of further resources

Flexible ordering of antibody class switch and V(D)J joining during B-cell ontogeny

V(D)J joining is mediated by RAG recombinase during early B-lymphocyte development in the bone marrow (BM). Activation-induced deaminase initiates isotype switching in mature B cells of secondary lymphoid structures. Previous studies questioned the strict ontological partitioning of these processes. We show that pro-B cells undergo robust switching to a subset of immunoglobulin H (IgH) isotypes. Chromatin studies reveal that in pro-B cells, the spatial organization of the Igh locus may restrict switching to this subset of isotypes. We demonstrate that in the BM, V(D)J joining and switching are interchangeably inducible, providing an explanation for the hyper-IgE phenotype of Omenn syndrome