Preparation of dilute magnetic semiconductor films by metalorganic chemical vapor deposition

A method for preparation of a dilute magnetic semiconductor (DMS) film is provided, in which a Group II metal source, a Group VI metal source and a transition metal magnetic ion source are pyrolyzed in the reactor of a metalorganic chemical vapor deposition (MOCVD) system by contact with a heated substrate. As an example, the preparation of films of Cd(sub 1-x)Mn(sub x)Te, in which 0 is less than or equal to x less than or equal to 0.7, on suitable substrates (e.g., GaAs) is described. As a source of manganese, tricarbonyl (methylcyclopentadienyl) manganese (TCPMn) is employed. To prevent TCPMn condensation during its introduction into the reactor, the gas lines, valves and reactor tubes are heated. A thin-film solar cell of n-i-p structure, in which the i-type layer comprises a DMS, is also described; the i-type layer is suitably prepared by MOCVD

Generation of Caustics and Spatial Rogue Waves from Nonlinear Instability

Caustics are natural phenomena in which nature concentrates the energy of waves. Although, they are known mostly in optics, caustics are intrinsic to all wave phenomena. For example, studies show that fluctuations in the profile of an ocean floor can generate random caustics and focus the energy of tsunami waves. Caustics share many similarities to rogue waves, as they both exhibit heavy-tailed distribution, i.e. an overpopulation of large events. Linear Schr\"odinger-type equations are usually used to explain the wave dynamics of caustics. However, in that the wave amplitude increases dramatically in caustics, nonlinearity is inevitable in many systems. In this Letter, we investigate the effect of nonlinearity on the formation of optical caustics. We show experimentally that, in contrast to linear systems, even small phase fluctuations can generate strong caustics upon nonlinear propagation. We simulated our experiment based on the nonlinear Schr\"odinger equation (NLSE) with Kerr-type nonlinearity, which describes the wave dynamics not only in optics, but also in some other physical systems such as oceans. Therefore, our results may also aid our understanding of ocean phenomena.Comment: 5 pages, 4 figure

Thermodynamic Interpretation of Field Equations at Horizon of BTZ Black Hole

A spacetime horizon comprising with a black hole singularity acts like a boundary of a thermal system associated with the notions of temperature and entropy. In case of static metric of BTZ black hole, the field equations near horizon boundary can be expressed as a thermal identity $dE = TdS + P_{r}dA$, where $E = M$ is the mass of BTZ black hole, $dA$ is the change in the area of the black hole horizon when the horizon is displaced infinitesimally small, $P_{r}$ is the radial pressure provided by the source of Einstein equations, $S= 4\pi a$ is the entropy and $T = \kappa / 2\pi$ is the Hawking temperature associated with the horizon. This approach is studied further to generalize it for non-static BTZ black hole and show that it is also possible to interpret the field equation near horizon as a thermodynamic identity $dE = TdS + P_{r}dA + \Omega_{+} dJ$, where $\Omega_{+}$ is the angular velocity and $J$ is the angular momentum of BTZ black hole. These results indicate that the field equations for BTZ black hole possess intrinsic thermodynamic properties near horizon.Comment: 8 page

Remote preoperative tonic-clonic seizures do not influence outcome after surgery for temporal lobe epilepsy.

OBJECTIVES: Tonic-clonic seizures are associated with greater chance of seizure relapse after anterior temporal lobectomy. We investigated whether the interval between the last preoperative tonic-clonic seizure and surgery relates to seizure outcome in patients with drug-resistant mesial temporal lobe epilepsy (MTLE). METHODS: In this retrospective study, patients were prospectively registered in a database from 1986 through 2014. Postsurgical outcome was categorized as seizure freedom or relapse. The relationship between surgical outcome and the interval between the last preoperative tonic-clonic seizure and surgery was investigated. RESULTS: One-hundred seventy-one patients were studied. Seventy nine (46.2%) patients experienced tonic-clonic seizures before surgery. Receiver operating characteristic curve of timing of the last preoperative tonic-clonic seizure was a moderate indicator to anticipate surgery failure (area under the curve: 0.657, significance; 0.016). The best cutoff that maximizes sensitivity and specificity was 27months; with a sensitivity of 0.76 and specificity of 0.60. Cox-Mantel analysis confirmed that the chance of becoming free of seizures after surgery in patients with no or remote history of preoperative tonic-clonic seizures was significantly higher compared with patients with a recent history (i.e., in 27months before surgery) (p=0.0001). CONCLUSIONS: The more remote the occurrence of preoperative tonic-clonic seizures, the better the postsurgical seizure outcome, with at least a two year gap being more favorable. A recent history of tonic-clonic seizures in a patient with MTLE may reflect more widespread epileptogenicity extending beyond the borders of mesial temporal structures

Facet modulation selective epitaxy–a technique for quantum-well wire doublet fabrication

The technique of facet modulation selective epitaxy and its application to quantum-well wire doublet fabrication are described. Successful fabrication of wire doublets in the AlxGa1–xAs material system is achieved. The smallest wire fabricated has a crescent cross section less than 140 Å thick and less than 1400 Å wide. Backscattered electron images, transmission electron micrographs, cathodoluminescence spectra, and spectrally resolved cathodoluminescence images of the wire doublets are presented

Schwarzschild-anti de Sitter within an Isothermal Cavity: Thermodynamics, Phase Transitions and the Dirichlet Problem

The thermodynamics of Schwarzschild black holes within an isothermal cavity and the associated Euclidean Dirichlet boundary-value problem are studied for four and higher dimensions in anti-de Sitter (AdS) space. For such boundary conditions classically there always exists a unique hot AdS solution and two or no Schwarzschild-AdS black-hole solutions depending on whether or not the temperature of the cavity-wall is above a minimum value, the latter being a function of the radius of the cavity. Assuming the standard area-law of black-hole entropy, it was known that larger and smaller holes have positive and negative specific heats and hence are locally thermodynamically stable and unstable respectively. In this paper we present the first derivation of this by showing that the standard area law of black-hole entropy holds in the semi-classical approximation of the Euclidean path integral for such boundary conditions. We further show that for wall-temperatures above a critical value a phase transition takes hot AdS to the larger Schwarzschild-AdS within the cavity. The larger hole thus can be globally thermodynamically stable above this temperature. The phase transition can occur for a cavity of arbitrary radius above a (corresponding) critical temperature. In the infinite cavity limit this picture reduces to that considered by Hawking and Page. The case of five dimensions is found to be rather special since exact analytic expressions can be obtained for the masses of the two holes as functions of cavity radius and temperature thus solving exactly the Euclidean Dirichlet problem. This makes it possible to compute the on-shell Euclidean action as functions of them from which other quantities of interest can be evaluated exactly.Comment: 23 pages, Late

Preparation of dilute magnetic semiconductor films by metalorganic chemical vapor deposition

A method for preparation of a dilute magnetic semiconductor (DMS) film is provided, wherein a Group II metal source, a Group VI metal source and a transition metal magnetic ion source are pyrolyzed in the reactor of a metalorganic chemical vapor deposition (MOCVD) system by contact with a heated substrate. As an example, the preparation of films of Cd.sub.1-x Mn.sub.x Te, wherein 0.ltoreq..times..ltoreq.0.7, on suitable substrates (e.g., GaAs) is described. As a source of manganese, tricarbonyl (methylcyclopentadienyl) maganese (TCPMn) is employed. To prevent TCPMn condensation during the introduction thereof int the reactor, the gas lines, valves and reactor tubes are heated. A thin-film solar cell of n-i-p structure, wherein the i-type layer comprises a DMS, is also described; the i-type layer is suitably prepared by MOCVD

Online Moodle Sebagai E-Learning Bagi Siswa SMK Peserta Praktek Kerja Industri

This study aims to integrate ICT by designing and applying online moodle as an e-learning material for class XII TKR.B students of SMK Negeri 1 Purworejo who undergo On Job Training for three months. In developing the e-learning, researchers use Research and Development method and ADDIE instructional design. Result of this study is the design and implementation of moodle as online learning media for OJT students. Teachers can upload learning modules and provide a test to determine the extent of students' understanding of material provided by the module. Online moodle can be accessed by students anytime and anywhere, either from mobile phone or internet cafes. All facilities provided in online moodle can easily be used as a medium of distance learning