Non-singular quantum improved rotating black holes and their maximal extension

We add a prescription to the Newman-Janis algorithm in order to use it as a means of finding new extended (`through r<0') rotating black hole spacetimes from static spherically symmetric ones. Then, we apply the procedure to a quantum improved black hole spacetime coming from Quantum Einstein Gravity. The goal is to get a maximally extended spacetime corresponding to a non-singular rotating black hole emulating the standard maximally extended Kerr black hole in regions where quantum effects are negligible. We rigourously check for the existence of scalar curvature singularities in the quantum improved rotating spacetime and we show that it is devoid of them. We also analyze the horizons and causal structure of the rotating black hole and provide Penrose diagrams for the maximally extended spacetime.Comment: 21 pages, 7 figures. Added references, comments and improved figure

A middleware for creating physical mashups of things

Indexación: Scopus.Nowadays, “things” deployed in cities are crucial to gather data to support decision making systems. Unfortunately, there is a low level of reuse of “things” between smart city applications of different organizations because “things” were unknown to developers or because it was harder to reuse them than use new ones due to technical details. In this ongoing work, we propose to convert “things” into active entities capable of discovering and organizing themselves driven by the applications goals’ satisfaction. Moreover, “things” are capable of collaborating between them in order to satisfy or maintain satisfied the published goals of applications. To validate the feasibility of our proposal, we are building mashThings, an Internet of Things (IoT) platform to build smart city applications as physical mashups, where the middleware layer is augmented by a multiagent layer of broker agents representing the available “things” in the city.http://ceur-ws.org/Vol-1950/paper11.pd

Peak statistics on COBE maps

We perform the stastistics of temperature maxima and minima in COBE-DMR 2-year maps. For power-law spectra the surface distribution of peaks implies an amplitude consistent with more conventional analyses of COBE data (for instance, we get $Q_{{\rm rms-PS}}=17\pm 3\ \mu$K for a spectral index $n=1),$ but not with the measured quadrupole $Q_{{\rm rms}}=6\pm 3\ \mu$K. This provides further support for the existence an infrared cutoff in the cosmic spectrum.Comment: Latex file, Astronomy & Astrophysics L-aa style. Hardcopy figures available separately, send requests to [email protected]

Singularity free gravitational collapse in an effective dynamical quantum spacetime

We model the gravitational collapse of heavy massive shells including its main quantum corrections. Among these corrections, quantum improvements coming from Quantum Einstein Gravity are taken into account, which provides us with an effective quantum spacetime. Likewise, we consider dynamical Hawking radiation by modeling its back-reaction once the horizons have been generated. Our results point towards a picture of gravitational collapse in which the collapsing shell reaches a minimum non-zero radius (whose value depends on the shell initial conditions) with its mass only slightly reduced. Then, there is always a rebound after which most (or all) of the mass evaporates in the form of Hawking radiation. Since the mass never concentrates in a single point, no singularity appears.Comment: 19 pages, 5 figure

The nuclear contacts and short range correlations in nuclei

Atomic nuclei are complex strongly interacting systems and their exact theoretical description is a long-standing challenge. An approximate description of nuclei can be achieved by separating its short and long range structure. This separation of scales stands at the heart of the nuclear shell model and effective field theories that describe the long-range structure of the nucleus using a mean- field approximation. We present here an effective description of the complementary short-range structure using contact terms and stylized two-body asymptotic wave functions. The possibility to extract the nuclear contacts from experimental data is presented. Regions in the two-body momentum distribution dominated by high-momentum, close-proximity, nucleon pairs are identified and compared to experimental data. The amount of short-range correlated (SRC) nucleon pairs is determined and compared to measurements. Non-combinatorial isospin symmetry for SRC pairs is identified. The obtained one-body momentum distributions indicate dominance of SRC pairs above the nuclear Fermi-momentum.Comment: Accepted for publication in Physics Letters. 6 pages, 2 figure