Gravitational Collapse of Inhomogeneous Dust in (2+1) Dimensions

We examine the gravitational collapse of spherically symmetric inhomogeneous dust in (2+1) dimensions, with cosmological constant. We obtain the analytical expressions for the interior metric. We match the solution to a vacuum exterior. We discuss the nature of the singularity formed by analyzing the outgoing radial null geodesics. We examine the formation of trapped surfaces during the collapse.Comment: Accepted for publication in CQ

Cosmology in three dimensions: steps towards the general solution

We use covariant and first-order formalism techniques to study the properties of general relativistic cosmology in three dimensions. The covariant approach provides an irreducible decomposition of the relativistic equations, which allows for a mathematically compact and physically transparent description of the 3-dimensional spacetimes. Using this information we review the features of homogeneous and isotropic 3-d cosmologies, provide a number of new solutions and study gauge invariant perturbations around them. The first-order formalism is then used to provide a detailed study of the most general 3-d spacetimes containing perfect-fluid matter. Assuming the material content to be dust with comoving spatial 2-velocities, we find the general solution of the Einstein equations with non-zero (and zero) cosmological constant and generalise known solutions of Kriele and the 3-d counterparts of the Szekeres solutions. In the case of a non-comoving dust fluid we find the general solution in the case of one non-zero fluid velocity component. We consider the asymptotic behaviour of the families of 3-d cosmologies with rotation and shear and analyse their singular structure. We also provide the general solution for cosmologies with one spacelike Killing vector, find solutions for cosmologies containing scalar fields and identify all the PP-wave 2+1 spacetimes.Comment: 35 pages, 2 figure

Dynamical formation and evolution of (2+1)-dimensional charged black holes

In this paper, we investigate the dynamical formation and evolution of 2 + 1-dimensional charged black holes. We numerically study dynamical collapses of charged matter fields in an anti de Sitter background and note the formation of black holes using the double-null formalism. Moreover, we include re-normalized energy-momentum tensors assuming the S-wave approximation to determine thermodynamical back-reactions to the internal structures. If there is no semi-classical effects, the amount of charge determines the causal structures. If the charge is sufficiently small, the causal structure has a space-like singularity. However, as the charge increases, an inner Cauchy horizon appears. If we have sufficient charge, we see a space-like outer horizon and a time-like inner horizon, and if we give excessive charge, black hole horizons disappear. We have some circumstantial evidences that weak cosmic censorship is still satisfied, even for such excessive charge cases. Also, we confirm that there is mass inflation along the inner horizon, although the properties are quite different from those of four-dimensional cases. Semi-classical back-reactions will not affect the outer horizon, but they will affect the inner horizon. Near the center, there is a place where negative energy is concentrated. Thus, charged black holes in three dimensions have two types of curvature singularities in general: via mass inflation and via a concentration of negative energy. Finally, we classify possible causal structures.Comment: 40 pages, 15 figure

Performance of the CMS High Granularity Calorimeter prototype to charged pion beams of 20−-300 GeV/c

The upgrade of the CMS experiment for the high luminosity operation of the LHC comprises the replacement of the current endcap calorimeter by a high granularity sampling calorimeter (HGCAL). The electromagnetic section of the HGCAL is based on silicon sensors interspersed between lead and copper (or copper tungsten) absorbers. The hadronic section uses layers of stainless steel as an absorbing medium and silicon sensors as an active medium in the regions of high radiation exposure, and scintillator tiles directly readout by silicon photomultipliers in the remaining regions. As part of the development of the detector and its readout electronic components, a section of a silicon-based HGCAL prototype detector along with a section of the CALICE AHCAL prototype was exposed to muons, electrons and charged pions in beam test experiments at the H2 beamline at the CERN SPS in October 2018. The AHCAL uses the same technology as foreseen for the HGCAL but with much finer longitudinal segmentation. The performance of the calorimeters in terms of energy response and resolution, longitudinal and transverse shower profiles is studied using negatively charged pions, and is compared to GEANT4 predictions. This is the first report summarizing results of hadronic showers measured by the HGCAL prototype using beam test data.Comment: To be submitted to JINS

Classical and quantum gravitational collapse in the Lemaitre–Tolman–Bondi model with a positive cosmological constant

Previous papers dealt with the quantization of the Lemaître–Tolman–Bondi (LTB) model for vanishing cosmological constant Λ. Here we extend the analysis to the case Λ > 0. Our main goal is to present solutions of the Wheeler–DeWitt equation, to give their interpretation and to derive Hawking radiation from them. We restrict ourselves to a discussion of those points that are different from the Λ = 0-case. These are mainly to do with the occurrence of two horizons

Recovery of Proteins and Chromium Complexes from Chromium – Containing Leather Waste (CCLW)

Chromium – Containing Leather Waste (CCLW) constitutes an environmental pollution problem to leather industries disposing the waste by landfill. The waste mainly consists of collagen and chromium III complexes. This work is a design of reactors to recover gelatin, polypeptides and chromium from CCLW. The results of the experiment shows that 68% of protein, based on dry weight of leather scraps, could be recovered. Three reactors with a total volume of 18 m3 was designed to handle 10,431 kg of waste generated from the tanning industries

Experience of Laparoscopic Incisional Hernia Repair in Kidney and/or Pancreas Transplant Recipients

Despite the wide popularity of laparoscopic incisional hernia repair (LIHR) in the nontransplant population, there are very few reports of LIHR available in abdominal organ transplant patients and none exclusively on kidney and/or pancreas (KP) transplant patients. We retrospectively reviewed a consecutive series of LIHR in KP transplant recipients performed over a period of 4 years and compared the results with LIHR in non-transplant patients during the same period. A total of 36 transplant patients were compared with 62 nontransplant patients. There were five patients converted to the open procedure in the transplant and four in nontransplant patients (p-NS). There were three seromas and one patient had a bowel perforation in the transplant group versus eight seromas, one bowel perforation and one small bowel obstruction noted in the nontransplant group. One patient in each group had a mesh infection requiring explant. Patients were followed up for a mean period of 2.2 years in the transplant group and 3 years in the nontransplant group. Overall there were five recurrences in the transplant group and four in the nontransplant group (p = NS). These results suggest that that LIHR is a safe and effective alternative to open repair

Experience of Laparoscopic Incisional Hernia Repair in Kidney and/or Pancreas Transplant Recipients

Despite the wide popularity of laparoscopic incisional hernia repair (LIHR) in the nontransplant population, there are very few reports of LIHR available in abdominal organ transplant patients and none exclusively on kidney and/or pancreas (KP) transplant patients. We retrospectively reviewed a consecutive series of LIHR in KP transplant recipients performed over a period of 4 years and compared the results with LIHR in non-transplant patients during the same period. A total of 36 transplant patients were compared with 62 nontransplant patients. There were five patients converted to the open procedure in the transplant and four in nontransplant patients (p-NS). There were three seromas and one patient had a bowel perforation in the transplant group versus eight seromas, one bowel perforation and one small bowel obstruction noted in the nontransplant group. One patient in each group had a mesh infection requiring explant. Patients were followed up for a mean period of 2.2 years in the transplant group and 3 years in the nontransplant group. Overall there were five recurrences in the transplant group and four in the nontransplant group (p = NS). These results suggest that that LIHR is a safe and effective alternative to open repair