Gravitation and thermodynamics: The einstein equation of state revisited

We perform an analysis where Einstein\u27s field equation is derived by means of very simple thermodynamical arguments. Our derivation is based on a consideration of the properties of a very small, spacelike two-plane in a uniformly accelerating motion. © 2009 World Scientific Publishing Company

Radiation of the Inner Horizon of the Reissner-Nordstr\"om Black Hole

Despite of over thirty years of research of the black hole thermodynamics our understanding of the possible role played by the inner horizons of Reissner-Nordstr\"om and Kerr-Newman black holes in black hole thermodynamics is still somewhat incomplete: There are derivations which imply that the temperature of the inner horizon is negative and it is not quite clear what this means. Motivated by this problem we perform a detailed analysis of the radiation emitted by the inner horizon of the Reissner-Nordstr\"om black hole. As a result we find that in a maximally extended Reissner-Nordstr\"om spacetime virtual particle-antiparticle pairs are created at the inner horizon of the Reissner-Nordstr\"om black hole such that real particles with positive energy and temperature are emitted towards the singularity from the inner horizon and, as a consequence, antiparticles with negative energy are radiated away from the singularity through the inner horizon. We show that these antiparticles will come out from the white hole horizon in the maximally extended Reissner-Nordstr\"om spacetime, at least when the hole is near extremality. The energy spectrum of the antiparticles leads to a positive temperature for the white hole horizon. In other words, our analysis predicts that in addition to the radiation effects of black hole horizons, also the white hole horizon radiates. The black hole radiation is caused by the quantum effects at the outer horizon, whereas the white hole radiation is caused by the quantum effects at the inner horizon of the Reissner-Nordstr\"om black hole.Comment: 22 pages, 6 figures. References added, discussion slightly expanded in Secs. I and V. To appear in IJMP

Effective Polymer Dynamics of D-Dimensional Black Hole Interiors

We consider two different effective polymerization schemes applied to D-dimensional, spherically symmetric black hole interiors. It is shown that polymerization of the generalized area variable alone leads to a complete, regular, single-horizon spacetime in which the classical singularity is replaced by a bounce. The bounce radius is independent of rescalings of the homogeneous internal coordinate, but does depend on the arbitrary fiducial cell size. The model is therefore necessarily incomplete. It nonetheless has many interesting features: After the bounce, the interior region asymptotes to an infinitely expanding Kantowski-Sachs spacetime. If the solution is analytically continued across the horizon, the black hole exterior exhibits asymptotically vanishing quantum-corrections due to the polymerization. In all spacetime dimensions except four, the fall-off is too slow to guarantee invariance under Poincare transformations in the exterior asymptotic region. Hence the four-dimensional solution stands out as the only example which satisfies the criteria for asymptotic flatness. In this case it is possible to calculate the quantum-corrected temperature and entropy. We also show that polymerization of both phase space variables, the area and the conformal mode of the metric, generically leads to a multiple horizon solution which is reminiscent of polymerized mini-superspace models of spherically symmetric black holes in Loop Quantum Gravity.Comment: 14 pages, 4 figures. Added discussion about the dependency on auxiliary structures. Matches with the published versio

Bleeding pancreatic pseudoaneurysms : management by angioembolization combined with therapeutic endoscopy

Bleeding pancreatic pseudocysts (PPCs) are a rare but lethal complication of pancreatitis. Transcatheter arterial embolization (TAE) is the first-line treatment of acute hemorrhage, but consensus on the definitive management of bleeding PPCs is lacking. The aim of this study was to evaluate the safety and efficacy of the combination of TAE and therapeutic endoscopy in the treatment of bleeding PPCs. Patients with acute or chronic pancreatitis treated for bleeding PPCs in Helsinki University Hospital during 2004-2014 comprised the study group. Inpatients with acute necrotizing pancreatitis were excluded. Patients underwent TAE as the primary treatment to control the bleeding. Therapeutic endoscopy performed on an outpatient visit after TAE allowed the definitive treatment of PPCs. A total of 58 patients underwent TAE. Re-bleeding rate (<30 days) was 15.5 %, necessitating re-embolization on seven and surgical intervention on two patients. Overall, TAE success rate was 96.6 %. Mortality rate (<30 days) was 3.4 %. Of the 58, 47 patients were followed up for their PPCs in our unit. PPCs resolved spontaneously in 13 (27.1 %). The remaining 34 had an endoscopic treatment attempt with endoscopic draining performed on 32 and unsuccessful cannulation on two (5.9 %). Of the 32 patients with initially successful endoscopy, 7 (21.9 %) needed an additional drainage procedure (six non-surgical and one surgical). Overall success rate of non-surgical management was 91.5 %. Post-endoscopy mortality rate (<30 days) was 2.9 %. Our follow-up continued for 15 (1-75) months. By the time of data retrieval, 35 of 58 patients had died with alcohol liver disease being the most common cause of death. Five-year survival estimate was 63 %. Bleeding pancreatic pseudoaneurysms require non-surgical management. We need more data on the optimal timing of therapeutic endoscopy and on the role of empirical embolizations.Peer reviewe

Climate-smart forestry case study: Finland

Non peer reviewe

The way forward: Management and policy actions

Non peer reviewe