Comment on: ``Zero temperature conductance of parallel T-shape double quantum dots'' [Physica E 39 (2007) 214, arXiv:0708.1842v1]

In a recent paper [Physica E 39 (2007) 214, arXiv:0708.1842v1] Crisan, Grosu and Tifrea revisited the problem of the conductance through a double quantum dot molecule connected to electrodes in a T-shape configuration. The authors obtained an expression for the conductance that disagrees with previous results in the literature. We point out an error in their derivation of the conductance formula and show that it gives unphysical results even for non-interacting quantum dots.Comment: 2 pages, no figure

Evaluating CAVM: A New Search-Based Test Data Generation Tool for C

We present CAVM (pronounced “ka-boom”), a new search-based test data generation tool for C. CAVM is developed to augment an existing commercial tool, CodeScroll, which uses static analysis and input partitioning to generate test data. Unlike the current state-of-the-art search-based test data generation tool for C, Austin, CAVM handles dynamic data structures using purely search-based techniques. We compare CAVM against CodeScroll and Austin using 49 C functions, ranging from small anti-pattern case studies to real world open source code and commercial code. The results show that CAVM can cover branches that neither CodeScroll nor Austin can, while also exclusively achieving the highest branch coverage for 20 of the studied functions

Higher dimensional dust collapse with a cosmological constant

The general solution of the Einstein equation for higher dimensional (HD) spherically symmetric collapse of inhomogeneous dust in presence of a cosmological term, i.e., exact interior solutions of the Einstein field equations is presented for the HD Tolman-Bondi metrics imbedded in a de Sitter background. The solution is then matched to exterior HD Scwarschild-de Sitter. A brief discussion on the causal structure singularities and horizons is provided. It turns out that the collapse proceed in the same way as in the Minkowski background, i.e., the strong curvature naked singularities form and that the higher dimensions seem to favor black holes rather than naked singularities.Comment: 7 Pages, no figure

Suppression of Superconducting Critical Current Density by Small Flux Jumps in MgB2MgB_2 Thin Films

By doing magnetization measurements during magnetic field sweeps on thin films of the new superconductor $MgB_2$, it is found that in a low temperature and low field region small flux jumps are taking place. This effect strongly suppresses the central magnetization peak leading to reduced nominal superconducting critical current density at low temperatures. A borderline for this effect to occur is determined on the field-temperature (H-T) phase diagram. It is suggested that the small size of the flux jumps in films is due to the higher density of small defects and the relatively easy thermal diffusion in thin films in comparison with bulk samples.Comment: 7 figures Phys. Rev. B accepted scheduled issue: 01 Feb 200

Asymmetry sum rule for molecular predissociation

© 2000 American Physical SocietyIn the case of weak diatomic molecular predissociation by noninteracting, optically inactive continuum states, it is demonstrated that the predissociation line shape is more accurately represented by a Beutler-Fano profile than by a Lorentzian. The weak asymmetry that is found to occur is due principally to interactions with neighboring vibrational resonances. For this type of predissociation in the case of multiple continua, a sum rule for the corresponding line-shape asymmetry is derived. This sum rule is verified numerically using single-channel and multichannel coupled Schrödinger-equation calculations for the Schumann-Runge band system of O2. Similar results are presented for the case of optically active continua.F. T. Hawes, L. W. Torop, B. R. Lewis and S. T. Gibso

Black hole thermodynamics with generalized uncertainty principle

In the standard viewpoint, the temperature of a stationary black hole is proportional to its surface gravity, $T_H=\hbar\kappa/2\pi$. This is a semiclassical result and the quantum gravity effects are not taken into consideration. This Letter explores a unified expression for the black hole temperature in the sense of a generalized uncertainty principle(GUP). Our discussion involves a heuristic analysis of a particle which is absorbed by the black hole. Besides a class of static and spherically symmetric black holes, an axially symmetric Kerr-Newman black hole is considered. Different from the existing literature, we suggest that the black hole's irreducible mass represent the characteristic size in the absorption process. The information capacity of a remnant is also discussed by Bousso's D-bound in de Sitter spacetime.Comment: 18 pages, great improvement on the first version; a Kerr-Newman black hole is considere

Supersymmetry and Branes in M-theory Plane-waves

We study brane embeddings in M-theory plane-waves and their supersymmetry. The relation with branes in AdS backgrounds via the Penrose limit is also explored. Longitudinal planar branes are originated from AdS branes while giant gravitons of AdS spaces become spherical branes which are realized as fuzzy spheres in the massive matrix theory.Comment: 17 pages, JHEP style, references added, typos correcte

Pumping in quantum dots and non-Abelian matrix Berry phases

We have investigated pumping in quantum dots from the perspective of non-Abelian (matrix) Berry phases by solving the time dependent Schr{\"o}dinger equation exactly for adiabatic changes. Our results demonstrate that a pumped charge is related to the presence of a finite matrix Berry phase. When consecutive adiabatic cycles are performed the pumped charge of each cycle is different from the previous ones

Thermodynamics of a black hole based on a generalized uncertainty principle

We study thermodynamic quantities and the stability of a black hole in a cavity using the Euclidean action formalism by Gibbons and Hawking based on the generalized uncertainty relation which is extended in a symmetric way with respect to the space and momentum without loss of generality. Two parameters in the uncertainty relation affect the thermodynamical quantities such as energy, entropy, and the heat capacity. In particular, it can be shown that the small black hole is unstable and it may decay either into a minimal black hole or a large black hole. We discuss a constraint for a large black hole comparable to the size of the cavity in connection with the critical mass.Comment: 12 pages, 4 figures; v2. to appear in JHE