Gravitational radiations of generic isolated horizons and non-rotating dynamical horizons from asymptotic expansions

Instead of using a three dimensional analysis on quasi-local horizons, we adopt a four dimensional asymptotic expansion analysis to study the next order contributions from the nonlinearity of general relativity. From the similarity between null infinity and horizons, the proper reference frames are chosen from the compatible constant spinors for an observer to measure the energy-momentum and flux near quasi-local horizons. In particular, we focus on the similarity of Bondi-Sachs gravitational radiation for the quasi-local horizons and compare our results to Ashtekar-Kirshnan flux formular. The quasi-local energy momentum and flux of generic isolated horizons and non-rotating dynamical horizons are discussed in this paper.Comment: PRD, 15 page

Domain wall space-times with a cosmological constant

We solve vacuum Einstein's field equations with the cosmological constant in space-times admitting 3-parameter group of isometries with 2-dimensional space-like orbits. The general exact solutions, which are represented in the advanced and retarded null coordinates, have two arbitrary functions due to the freedom of choosing null coordinates. In the thin-wall approximation, the Israel's junction conditions yield one constraint equation on these two functions in spherical, planar, and hyperbolic domain wall space-times with reflection symmetry. The remain freedom of choosing coordinates are completely fixed by requiring that when surface energy density $\sigma_0$ of domain walls vanishes, the metric solutions will return to some well-known solutions. It leads us to find a planar domain wall solution, which is conformally flat, in the de Sitter universe.Comment: 9 pages. no figur

Quasi-local mass in the covariant Newtonian space-time

In general relativity, quasi-local energy-momentum expressions have been constructed from various formulae. However, Newtonian theory of gravity gives a well known and an unique quasi-local mass expression (surface integration). Since geometrical formulation of Newtonian gravity has been established in the covariant Newtonian space-time, it provides a covariant approximation from relativistic to Newtonian theories. By using this approximation, we calculate Komar integral, Brown-York quasi-local energy and Dougan-Mason quasi-local mass in the covariant Newtonian space-time. It turns out that Komar integral naturally gives the Newtonian quasi-local mass expression, however, further conditions (spherical symmetry) need to be made for Brown-York and Dougan-Mason expressions.Comment: Submit to Class. Quantum Gra

Clinical application of platelet-rich fibrin as the sole grafting material in periodontal intrabony defects

AbstractBackground/purposePlatelet-rich fibrin (PRF) obtained by Choukroun’s technique is a healing biomaterial that concentrates in a single autologous fibrin membrane, mostly of platelets and cytokines from blood harvest, and without any artificial biochemical modification. However, no data are presently available concerning the use of PRF for the treatment of periodontal intrabony defects. This report was to present the clinical and radiographic changes of a patient with periodontal intrabony defects treated with PRF.Material and methodsThe left mandibular first molar (#36) and left maxillary second molar (#27) with intrabony defects were filled with PRF as the sole grafting material in a 38-year-old female patient. The primary outcomes evaluated in this study included changes in probing depth, attachment level, and radiographic bone density between baseline and 6 months postoperatively.ResultsThe results showed that the application of PRF as the sole grafting material in intrabony defects exhibited pocket reduction and gain in clinical attachment after 3 months and 6 months. Using National institute of health program, the 6 months postoperative radiographic density of images for #27 and #36 showed an increase of 1.6 and 1.3 fold compared with each preoperative radiography, respectively.ConclusionsFrom a clinical and radiologic point of view at 6 months after surgery, the use of PRF as the sole grafting material seems to be an effective modality of regenerative treatment for periodontal intrabony defects