Controlled acceleration of a modulated quantum bouncer

Cold atoms bouncing on a modulated atomic mirror exhibit dynamic localization and acceleration subject to modulated strength. We explain the characteristics of acceleration using accelerated mapping and define control parameters. We show that the effective Planck’s constant plays a vital role in limiting overall linear growth of accelerated atoms with time. For large values of the effective Planck’s constant, the atomic quantum accelerated is seized if the localization window overlaps the accelerated window.     

The behaviour of vortex lines near the surfaces of a uniaxial anisotropic superconducting quarter space

The behaviour of the distorted vortex lattice near the surfaces of a uniaxial anisotropic superconducting quarter-space is studied. The analytical solution of the distributions of the fields inside and outside the sample as well as the current density are calculated in an integral form. Using these solutions, the forces on the vortex segments are completely determined. The Gibbs free energy of the system is investigated in a simple form. Agreement with previous results is found in the isotropic limiting case. Moreover, in some limiting cases, good agreement with the results obtained for a high temperature superconducting semi-infinite space is achieved.     

Nanowire-based devices combining light guiding and photodetection

We demonstrate bridged nanowires on a non-single-crystal substrate as a versatile fabrication approach to combine active and passive photonic functionalities on silicon platforms. Silicon nanowires are grown on vertical non-single-crystal surfaces by a vapor-liquid-solid process and bridge a microtrench obtained by etching an amorphous optical rib waveguide. A pair of phosphorous-doped polysilicon electrodes is deposited on the walls of the waveguide microtrench for seeding the nanowire synthesis and for electrical interfacing. The bridged nanowires act as photoconductors and their photoresponse to edge-illumination from waveguided light is characterized. Taking advantage of crystalline nanowire growth on non-single-crystal substrates may ultimately lead to substrate-independent integration of best-of-breed semiconductor nanodevices for applications such as photonic integrated circuits.     

On weaker forms for concepts in theory of topological groupoids

In this paper, we investigate the topologically weak concepts of topological groupoids by giving the concepts of α-topological groupoid and α-topological subgroupoid. Furthermore, we show the role of the density condition to allow α-topological subgroupoid inherited properties from α-topological groupoid and the irresoluteness property for the structure maps in α-topological groupoid is studied. We also give some results about the fibers of α-topological groupoids.     

Signals of left-right supersymmetry in e + e − collisions

We study chargino and neutralino pair production at the Next Linear e⁺ e^? Collider in a supersymmetric left-right model. We investigate on- and off-resonance signals via the processes: $e^{+}e^{-}?ghtarrow {?lde chi}_{1}^{+}{?lde chi}_{1}^{-} ?ghtarrow e^{+}e^{-}+{? p}_{? miss}$ and $e^{+}e^{-}?ghtarrow {?lde chi}_{2}^{0}{?lde chi}_{1}^{0} ?ghtarrow e^{+}e^{-}+{? p}_{? miss}$. These reactions could lead to observable signals as they compare with the background signal from W^± -pair production.     

A novel interconnection technique for manufacturing nanowire devices

This paper reviews a novel bridging technique that connects a large number of highly directional metal-catalyzed nanowires between pre-fabricated electrodes and extends the technique to an electrically isolated structure that allows conduction through the nanowires to be measured. Two opposing vertical and electrically isolated semiconductor surfaces are fabricated using coarse optical lithography, along with wet and dry etching. Lateral nanowires are then grown from one surface by metal-catalyst-assisted chemical vapor deposition; nanowires connect to the other vertical surface during growth, forming mechanically robust nanobridges. By forming the structure on a silicon-on-insulator substrate, electrical isolation is achieved. Electrical measurements indicate that dopant added during nanowire growth is electrically active and of the same magnitude as in planar epitaxial layers. PACS 61.46.+w; 62.25.+g; 68.65.-k; 73.63.-b; 73.63.Bd     

Switching between positive and negative permeability by photoconductive coupling for modulation of electromagnetic radiation

We introduce a modulation mechanism for negative index materials (NIM) in the GHz frequency range by means of photoconductive coupling. This leads the way to a monolithically integrated modulable NIM achieved by conventional microfabrication techniques. The photosensitive material is deposited in the gap of the split ring resonator (SRR) structure and the response in terms of S-parameters is simulated using a high frequency structure simulator (HFSS^TM) program. Only a single SRR particle is simulated to demonstrate total suppression of resonance amplitude and without any loss of generality the concept is applicable to a NIM comprising of both negative permeability and negative permittivity. This simple modulation of refractive indices can lead to novel optical device developments with the potential to dramatically improve the performance of existing phased array antennas, optical beam-forming networks, antenna remoting and transportation of RF power through fiber. PACS 42.60.Fc; 42.82.Cr; 81.05; 73.50.Pz     

Chargino-neutralino production inp\bar p-collisions for the left-right supersymmetric model

An extension of the Supersymmetric Standard Model to the supersymmetricSU(2) _L×SU(2) _R×U(1) _B–L model is considered. The gauge group contains a bidoublet and triplet Higgs field. We investigate the possibility of detecting chargino and neutralino production in -collisions atCDF, namely . A numerical analysis is performed for , tan 1 and a lower bound on the lightest supersymmetric particle (LSP) mass, GeV. Using conservative assumptions ofM _WR300 GeV andgg _Lg _R, we find the cross sections are: , and pb, and thus _L 24 _L at TeV. Cross sections are also given for larger values of the center of mass energy up to those available at the SSC. The results are compared with the prompt-lepton background of theW _{L, R} ^– decays from . Both decays for bosons show Jacobian peaks for (p _T150 GeV forM _WR) at =90°. Furthermore the chargino signature unlike the promptlepton background is symmetric under the Jacobian peak. We also exhibit the dependence of the angular distribution of the chargino on the c.m. angle forp _T40 GeV, 150 GeV at TeV.     

Triplet state photosensitization of nanocrystalline metal oxide electrodes by zinc-substituted cytochrome c: application to hydrogen evolution

The interfacing of nanostructured semiconductor photoelectrodes with redox proteins is an innovative approach to the development of artificial photosynthetic systems. In this paper, we have investigated the photoinduced electron-transfer reactions of zinc-substituted cytochrome c, ZnCyt-c, immobilized on mesoporous, nanocrystalline metal oxide electrodes. Efficient electron injection from the triplet state of ZnCyt-c is observed into TiO(2) electrodes (t(50%) approximately 100 micros) resulting in a long-lived charge-separated state (lifetime of up to 0.4 s). Further studies were undertaken as a function of electrolyte pH and metal oxide employed. Optimum yield of a long-lived charge-separated state was observed employing TiO(2) electrodes at pH 5, consistent with our previous studies of analogous dye-sensitized metal oxide electrodes. The addition of EDTA as a sacrificial electron donor to the electrolyte resulted in efficient photogeneration of molecular hydrogen, with a quantum yield per one absorbed photon of 10 +/- 5%.     

A new spectrophotometric method for the determination of promethazine-HCl from pure and pharmaceutical preparations

Promethazine-HCl reacts with potassium persulphate to give a pinkish red color complex exhibiting maximum absorbance at 515 nm. The reaction is selective for promethazine-HCl, with 1 μg/mL as visual limit of identification and provides a basis for a new spectrophotometric determination method. The color forming reaction obeys Beer's Law from 0.001 to 0.125 mg/mL of promethazine-HCl. The relative standard deviation does not exceed 0.005 mg/mL. The method is successfully applied to pure and pharmaceutical formulations of promethazine-HCl. The quantitative assessment of tolerable amounts of possible interferants was also studied. The results are reproducible within ±1% and in good agreement with those obtained by the standard procedure.