CFTs in rotating black hole backgrounds

We use AdS/CFT to construct the gravitational dual of a 5D CFT in the background of a non-extremal rotating black hole. Our boundary conditions are such that the vacuum state of the dual CFT corresponds to the Unruh state. We extract the expectation value of the stress tensor of the dual CFT using holographic renormalisation and show that it is stationary and regular on both the future and the past event horizons. The energy density of the CFT is found to be negative everywhere in our domain and we argue that this can be understood as a vacuum polarisation effect. We construct the solutions by numerically solving the elliptic Einstein--DeTurck equation for stationary Lorentzian spacetimes with Killing horizons.Comment: 20 + 13 pages, 3 appendices. (Updated to match the content of published version. One extra appendix added.

Xifrat de fitxers ACA de HD-DVD amb AACS

Aquest projecte tracta de com es protegeixen els discs HD-DVD fent servir l’estàndard de protecció AACS de molt recent creació. S’expliquen també els mètodes criptogràfics que s’utilitzen: AES-128, SHA-1 i CMAC. Implementant en C++ el mètode CMAC. Dins dels discs HD-DVD hi ha dos tipus de continguts que es poden protegir, per una banda està el contingut audiovisual i per l’altra els fitxers de recursos avançats (ARF) que composen els menús de navegació, efectes de so, programació... Els fitxers de recursos avançats s’acostumen a empaquetar dins d’un fitxer que s’anomena ACA, aquest procés per si sol no té seguretat i és per tant on intervé l’AACS, per donar-li protecció. Amb la finalitat d’acabar d’entendre tot el mecanisme de l’AACS i en concret el mètode de protecció d’aquests ACA s’ha dissenyat i implementat una aplicació que protegeix, desprotegeix i verifica aquests ARF abans d’empaquetar-se dins d’un fitxer ACA. Obtenint així fitxers ACA xifrats quan aquests es creen a partir dels ARF’s protegits. L’aplicació s’ha creat en c++ per ser executada des de línia de comandes i s’ha programat de tal manera que es pugui fer servir per Linux i per Windows. Quan s’intenta desprotegir un fitxer l’aplicació actua com si fos un reproductor de HD-DVD compatible amb AACS i fa les verificacions de seguretat pertinents abans d’acceptar o descartar el fitxer. Presenta els resultats i indica la raó pel rebuig del fitxer si s’escau

Integrability of Five Dimensional Minimal Supergravity and Charged Rotating Black Holes

We explore the integrability of five-dimensional minimal supergravity in the presence of three commuting Killing vectors. We argue that to see the integrability structure of the theory one necessarily has to perform an Ehlers reduction to two dimensions. A direct dimensional reduction to two dimensions does not allow us to see the integrability of the theory in an easy way. This situation is in contrast with vacuum five-dimensional gravity. We derive the Belinski-Zakharov (BZ) Lax pair for minimal supergravity based on a symmetric 7x7 coset representative matrix for the coset G2/(SL(2,R) x SL(2,R)). We elucidate the relationship between our BZ Lax pair and the group theoretic Lax pair previously known in the literature. The BZ Lax pair allows us to generalize the well-known BZ dressing method to five-dimensional minimal supergravity. We show that the action of the three-dimensional hidden symmetry transformations on the BZ dressing method is simply the group action on the BZ vectors. As an illustration of our formalism, we obtain the doubly spinning five-dimensional Myers-Perry black hole by applying solitonic transformations on the Schwarzschild black hole. We also derive the Cvetic-Youm black hole by applying solitonic transformations on the Reissner-Nordstrom black hole.Comment: 44 pages, 4 figure

Indirect test of M-S circuits using multiple specification band guarding

Testing analog and mixed-signal circuits is a costly task due to the required test time targets and high end technical resources. Indirect testing methods partially address these issues providing an efficient solution using easy to measure CUT information that correlates with circuit performances. In this work, a multiple specification band guarding technique is proposed as a method to achieve a test target of misclassified circuits. The acceptance/rejection test regions are encoded using octrees in the measurement space, where the band guarding factors precisely tune the test decision boundary according to the required test yield targets. The generated octree data structure serves to cluster the forthcoming circuits in the production testing phase by solely relying on indirect measurements. The combined use of octree based encoding and multiple specification band guarding makes the testing procedure fast, efficient and highly tunable. The proposed band guarding methodology has been applied to test a band-pass Butterworth filter under parametric variations. Promising simulation results are reported showing remarkable improvements when the multiple specification band guarding criterion is used.Peer ReviewedPostprint (author's final draft

End Point of Black Ring Instabilities and the Weak Cosmic Censorship Conjecture.

This is the author accepted manuscript. The final version is available at http://journals.aps.org/prl/abstract/10.1103/PhysRevLett.116.071102#fulltext.We produce the first concrete evidence that violation of the weak cosmic censorship conjecture can occur in asymptotically flat spaces of five dimensions by numerically evolving perturbed black rings. For certain thin rings, we identify a new, elastic-type instability dominating the evolution, causing the system to settle to a spherical black hole. However, for sufficiently thin rings the Gregory-Laflamme mode is dominant, and the instability unfolds similarly to that of black strings, where the horizon develops a structure of bulges connected by necks which become ever thinner over time.We are very grateful to Garth Wells (Dept. Engineering, U. Cambridge) for suggesting to us the shock capturing technique which has proven so valuable in this work. We would like to thank J. Briggs, J. Camps, R. Emparan, J. Jäykkä, K. Kornet, L. Lehner, F. Pretorius, H. Reall, E. Schnetter, U. Sperhake, T. Wiseman and H. Witek for numerous stimulating discussions. P.F. would like to especially thank E. Schnetter and U. Sperhake for early collaboration in this project. We are very grateful to our collaborators and co-developers of the GRC HOMBO code, K. Clough, E. Lim and H. Finkel. We would also like to thank J. Santos and B. Way for allowing us to display their data in Fig. 1. A significant part of this work was undertaken on the COSMOS Shared Memory system at DAMTP, University of Cambridge, operated on behalf of the STFC DiRAC HPC Facility. This equipment is funded by BIS National E-infrastructure capital Grant No. ST/J005673/1 and STFC Grants No. ST/H008586/1, No. ST/K00333X/1. Further portions of this research were conducted with high performance computational resources provided by Louisiana State University [31] on its SuperMike-II cluster under allocation NUMREL06. The authors also acknowledge HPC resources from the NSF-XSEDE Grant No. PHY-090003, provided by the Texas Advanced Computing Center (TACC) at The University of Texas at Austin on its Stampede cluster, and by the San Diego Supercomputer Center (SDSC) at UC San Diego on its Comet cluster. P.F. and S.T. were supported by the European Research Council Grant No. ERC-2011-StG 279363- HiDGR. P.F. was also supported by the Stephen Hawking Advanced Research Fellowship from the Centre for Theoretical Cosmology, University of Cambridge. P.F. is currently supported by a Royal Society University Research Fellowship and by the European Research Council Grant No. ERC-2014-StG 639022-NewNGR. MK is supported by an STFC studentship. P.F. wants to thank Perimeter Institute and Princeton University for hospitality during various stages of this work

Motivos paganos en mosaicos cristianos y judíos de oriente : problemática e interpretación (V)

Como complemento a los temas estudiados en los cuatro artículos anteriores de la serie, en este último se han recogido los motivos de origen pagano en mosaicos bizantinos orientales que no pertenecían a iglesias o sinagogas sino a casas señoriales, villas rústicas y oficinas de administración civil. Algunos de los motivos son personajes que podemos interpretar como simples personificaciones de conceptos abstractos, como "el tiempo". Otros son seres o escenas mitológicas, algunas de ellas con posible significado o aplicación moral, tal vez refiriéndose al destino de la sala. Las escenas dionisíacas expresan artísticamente un deseo o augurio de felicidad en la vida. Como apéndice, se discute la difícil inscripción «Obra de Alejandro», y una conclusión final resume en cinco puntos los resultados de todo el estudio.This article completes the themes discussed in the four preceding articles of the series. It deals with pagan motifs in Eastern mosaics that belonged not to churches or synagogues, but to mansions, rustic villas and offices of civil administration. Some of the motifs here discussed are human figures that can be interpreted as simple personifications of abstract concepts, such as the time. Others are mythological beings or scenes, some of them with a possible moral meaning, others conveying a moral iesson linked to the destination of the hall in question.The Dionysiac scenes are to be seen as an artistic expression of a wish for happiness in life.The inscription «Alexander's work» is discussed in appendix, and a five point resume concludes the results of the whole study