Strings, Junctions and Stability

Identification of string junction states of pure SU(2) Seiberg-Witten theory as B-branes wrapped on a Calabi-Yau manifold in the geometric engineering limit is discussed. The wrapped branes are known to correspond to objects in the bounded derived category of coherent sheaves on the projective line \cp{1} in this limit. We identify the pronged strings with triangles in the underlying triangulated category using Pi-stability. The spiral strings in the weak coupling region are interpreted as certain projective resolutions of the invertible sheaves. We discuss transitions between the spiral strings and junctions using the grade introduced for Pi-stability through the central charges of the corresponding objects.Comment: 15 pages, LaTeX; references added. typos correcte

Chemical extraction and optimization of intracellular β-galactosidase production from the bacterium Arthrobacter oxydans using Box-Behnken design of response surface methodology

Present study demonstrated the isolation of most promising β-galactosidase producing bacterial strain SB from soil. Morphological, biochemical, and 16s rRNA sequence analysis identified the bacterial strain as Arthrobacter oxydans. Several chemicals, including SDS, Triton X-100, Tween 20, isoamyl alcohol, and toluene-acetone mixture, were applied for extraction of intracellular β-galactosidase from the bacterial strain Arthrobacter oxydans. Among these, Tween 20 was recorded to be most effective. Role of pH, temperature, and shaker speed on production of β-galactosidase was evaluated using Box-Behnken design of response surface methodology. According to Box-Behnken analysis, optimum production of β-galactosidase (21.38 U (mg–1 protein)) is predicted at pH 6.76, temperature 36.1 °C, and shaker speed 121.37 r.p.m. The parameters are validated with the nearest value

Analytical estimate of open-circuit voltage of a Schottky-barrier solar cell under high level injection

The open-circuit voltage developed across a Schottky-Barrier (SB) solar cell was theoretically modeled to estimate it under high level injection conditions. An Open-circuit voltage (Voc) of 0.709 V was obtained for specific metal/n-Si SB solar cell. A substantial increase of 42.6 % in Voc was noticed while comparing our result with that previously calculated in low level injection conditions. Four different metals suitable for making Schottky contact with n-Si were investigated and calculated the variation of Voc with different values of doping concentrations in the semiconductor. The effect of surface recombination velocities (SRV) of charge carriers on Voc was also estimated at such high level injections. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2789

Optical and Electronic Properties of Double Perovskite Ba2ScSbO6

Ba2ScSbO6 (BSS) has been synthesized in polycrystalline form by solid state reaction. Structural characterization of the compound was done through X-ray diffraction (XRD) followed by Riedvelt analysis of the XRD pattern. The crystal structure is cubic, space group Fm-3m (No. 225. Optical band-gap of the present system has been calculated using the UV-Vis Spectroscopy to be 4.2eV. A detailed study of the electronic properties has also been carried out using the Full-Potential Linear Augmented Plane Wave (FPLAPW) as implemented in WIEN2k. BSS is found to be a large band-gap insulator with potential technological applications, such as dielectric resonators and filers in microwave applicationsComment: 4 pages, 3 figures. arXiv admin note: text overlap with arXiv:1309.678

Analytical estimate of open-circuit voltage of a Schottky-barrier solar cell under high level injection

The open-circuit voltage developed across a Schottky-Barrier (SB) solar cell was theoretically modeled to estimate it under high level injection conditions. An Open-circuit voltage (Voc) of 0.709 V was obtained for specific metal/n-Si SB solar cell. A substantial increase of 42.6 % in Voc was noticed while comparing our result with that previously calculated in low level injection conditions. Four different metals suitable for making Schottky contact with n-Si were investigated and calculated the variation of Voc with different values of doping concentrations in the semiconductor. The effect of surface recombination velocities (SRV) of charge carriers on Voc was also estimated at such high level injections. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2789

Dynamics of a metastable state nonlinearly coupled to a heat bath driven by an external noise

Based on a system-reservoir model, where the system is nonlinearly coupled to a heat bath and the heat bath is modulated by an external stationary Gaussian noise, we derive the generalized Langevin equation with space dependent friction and multiplicative noise and construct the corresponding Fokker-Planck equation, valid for short correlation time, with space dependent diffusion coefficient to study the escape rate from a metastable state in the moderate to large damping regime. By considering the dynamics in a model cubic potential we analyze the result numerically which are in good agreement with the theoretical prediction. It has been shown numerically that the enhancement of rate is possible by properly tuning the correlation time of the external noise.Comment: 13 pages, 5 figures, Revtex4. To appear in Physical Review

Stochastic Energetics of Quantum Transport

We examine the stochastic energetics of directed quantum transport due to rectification of non-equilibrium thermal fluctuations. We calculate the quantum efficiency of a ratchet device both in presence and absence of an external load to characterize two quantifiers of efficiency. It has been shown that the quantum current as well as efficiency in absence of load (Stokes efficiency) is higher as compared to classical current and efficiency, respectively, at low temperature. The conventional efficiency of the device in presence of load on the other hand is higher for a classical system in contrast to its classical counterpart. The maximum conventional efficiency being independent of the nature of the bath and the potential remains the same for classical and quantum systems.Comment: To be published in Phys. Rev.