An improved estimate of black hole entropy in the quantum geometry approach

A proper counting of states for black holes in the quantum geometry approach shows that the dominant configuration for spins are distributions that include spins exceeding one-half at the punctures. This raises the value of the Immirzi parameter and the black hole entropy. However, the coefficient of the logarithmic correction remains -1/2 as before.Comment: 5 pages, LaTeX; references and remarks adde

Cubic anisotropy in high homogeneity thin (Ga,Mn)As layers

Historically, comprehensive studies of dilute ferromagnetic semiconductors, e.g., $p$-type (Cd,Mn)Te and (Ga,Mn)As, paved the way for a quantitative theoretical description of effects associated with spin-orbit interactions in solids, such as crystalline magnetic anisotropy. In particular, the theory was successful in explaining {\em uniaxial} magnetic anisotropies associated with biaxial strain and non-random formation of magnetic dimers in epitaxial (Ga,Mn)As layers. However, the situation appears much less settled in the case of the {\em cubic} term: the theory predicts switchings of the easy axis between in-plane $\langle 100\rangle$ and $\langle 110\rangle$ directions as a function of the hole concentration, whereas only the $\langle 100\rangle$ orientation has been found experimentally. Here, we report on the observation of such switchings by magnetization and ferromagnetic resonance studies on a series of high-crystalline quality (Ga,Mn)As films. We describe our findings by the mean-field $p$-$d$ Zener model augmented with three new ingredients. The first one is a scattering broadening of the hole density of states, which reduces significantly the amplitude of the alternating carrier-induced contribution. This opens the way for the two other ingredients, namely the so-far disregarded single-ion magnetic anisotropy and disorder-driven non-uniformities of the carrier density, both favoring the $\langle 100\rangle$ direction of the apparent easy axis. However, according to our results, when the disorder gets reduced a switching to the $\langle 110\rangle$ orientation is possible in a certain temperature and hole concentration range.Comment: 12 pages, 9 figure

Post-growth annealing of GaMnAs under As capping - an alternative way to increase Tc

We demonstrate that in situ post-growth annealing of GaMnAs layers under As capping is adequate for achieving high Curie temperatures (Tc) in a similar way as ex situ annealing in air or in N2 atmosphere practiced earlier.Comment: 13 pages, 4 figure

Spatially controlled formation of superparamagnetic (Mn,Ga)As nanocrystals in high temperature annealed (Ga,Mn)As/GaAs superlattices

The annealing-induced formation of (Mn,Ga)As nanocrystals in (Ga,Mn)As/GaAs superlattices was studied by X-ray diffraction, transmission electron microscopy and magnetometry. The superlattice structures with 50 A thick (Ga,Mn)As layers separated by 25, 50 and 100 A thick GaAs spacers were grown by molecular beam epitaxy at low temperature (250 C), and then annealed at high temperatures of: 400, 560 and 630 C. The high temperature annealing causes decomposition to GaMnAs ternary alloy and formation of (Mn,Ga)As nanocrystals inside the GaAs matrix. The nanocrystals are confined in the planes that were formerly occupied by (Ga,Mn)As layers for up to the 560 C of annealing and diffuse throughout the GaAs spacer layers at 630 C annealing. The corresponding magnetization measurements show the evolution of the magnetic properties of as-grown and annealed samples from ferromagnetic, through superparamagnetic to the combination of both.Comment: 14 pages, 3 figure

Computing Black Hole entropy in Loop Quantum Gravity from a Conformal Field Theory perspective

Motivated by the analogy proposed by Witten between Chern-Simons and Conformal Field Theories, we explore an alternative way of computing the entropy of a black hole starting from the isolated horizon framework in Loop Quantum Gravity. The consistency of the result opens a window for the interplay between Conformal Field Theory and the description of black holes in Loop Quantum Gravity.Comment: 9 page

Synchrotron x-ray topographic and high-resolution diffraction analysis of mask-induced strain in epitaxial laterally overgrown GaAs layers

Synchrotron x-ray back reflection section topographs of epitaxial lateral overgrown (ELO) GaAs samples grown on (001) GaAs substrates show images of the GaAs layers bent due to the interaction between the layer and the SiO2 mask. The topographs are simulated under the assumption of orientational contrast. Using the same data the measured x-ray diffraction curve is simulated. The calculations, which are in good agreement with the measurements, are used to gain information on the tilted (001) lattice planes in each ELO layer. We show that the bending of ELO lattice planes reaches a maximum at the center of the ELO stripes, where misorientation is at a minimum, and decreases towards the edges of the stripes, where misorientation reaches a maximum

Thermally activated decomposition of (Ga,Mn)As thin layer at medium temperature post growth annealing

The redistribution of Mn atoms in Ga1-xMnxAs layer during medium-temperature annealing, 250-450 oC, by Mn K-edge X-ray absorption fine structure (XAFS) recorded at ALBA facility, was studied. For this purpose Ga1-xMnxAs thin layer with x=0.01 was grown on AlAs buffer layer deposited on GaAs(100) substrate by molecular beam epitaxy (MBE) followed by annealing. The examined layer was detached from the substrate using a “lift-off” procedure in order to eliminate elastic scattering in XAFS spectra. Fourier transform analysis of experimentally obtained EXAFS spectra allowed to propose a model which describes a redistribution/diffusion of Mn atoms in the host matrix. Theoretical XANES spectra, simulated using multiple scattering formalism (FEFF code) with the support of density functional theory (WIEN2k code), qualitatively describe the features observed in the experimental fine structure

Right posterior segment graft for living donor liver transplantation: A systematic review

The clinical significance of the right posterior segment (RPS) graft in living donor liver transplantation (LDLT) is unknown because of its limited use and technical concerns. This study aimed to review published studies investigating outcomes of RPS grafts. The systematic literature search was conducted to retrieve data from Embase, Medline Ovid, Web of Science, Cochrane CENTRAL, and Google Scholar. Among the 388 articles, six retrospective studies from Asian countries were included. The overall incidences of major and minor complications after RPS graft procurement were 5.6% and 34.6%, respectively and no donor deaths were reported. RPS graft recipients had the following postoperative complications: overall mortality rate, 14.5%; bile leakage, 8.7%, biliary stenosis, 18.8%, hepatic artery thrombosis, 8.7%, and liver re-transplantation, 2.9%. The RPS graft can be considered as an option for a living liver graft respecting donor safety under strict selection criteria and surgical strategy. The precise evaluation and understanding of anatomical variations and volumetric a

Current evidence of nutritional therapy in pancreatoduodenectomy: Systematic review of randomized controlled trials

Aim: Evidence of nutritional therapies in pancreatoduodenectomy (PD) has been shown. However, few studies focus on the association between different nutritional therapies and outcomes. The aim of this review was to summarize the current evidence of nutritional therapies such as enteral nutrition (EN), immunonutrition, and synbiotics on postoperative outcomes after PD. Methods: A systematic literature search of Embase, Medline Ovid, and Cochrane CENTRAL was done to summarize the available evidence, including randomized controlled trials, meta‐analyses and reviews, regarding nutritional therapy in PD. Results: A total of 20 randomized controlled trials were included in this review. Safety and tolerability of EN in PD was shown. Giving postoperative EN can shorten length of stay compared to parenteral nutrition; however, the effect of EN on postoperative complications remains controversial. Postoperative EN should be given only on selective indications rather than routinely used, and preoperative EN is indicated only in patients with severe malnutrition. Giving preoperative immunonutrition is considered to reduce the incidence of infectious complications; however, evidence level is moderate and recommendation grade is weak. The beneficial effect of perioperative synbiotics on postoperative infectious complications is limited. Furthermore, the effectiveness of other nutritional supplements remains unclear. Conclusion: Recently, evidence of enhanced recovery after surgery (ERAS) in PD has been increasing. Early oral intake with systematic nutritional support is an important aspect of the ERAS concept. Future well‐designed studies should investigate the impact of systematic nutritional therapies on outcomes following PD