Electrical polarization of nuclear spins in a breakdown regime of quantum Hall effect

We have developed a method for electrical polarization of nuclear spins in quantum Hall systems. In a breakdown regime of odd-integer quantum Hall effect (QHE), excitation of electrons to the upper Landau subband with opposite spin polarity dynamically polarizes nuclear spins through the hyperfine interaction. The polarized nuclear spins in turn accelerate the QHE breakdown, leading to hysteretic voltage-current characteristics of the quantum Hall conductor.Comment: 3 pages, 4 figures, submitted to Appl. Phys. Let

The development of air shower in the iron absorber

The iron open-sandwich experiments to observe one dimensional development of individual air showers were carried out at Akeno Observatory. One dimensional energy flow, incident energy and production height of shower is estimated using the data of size and age obtained from the above experiment and simple calculation

Electron spin phase relaxation of phosphorus donors in nuclear spin enriched silicon

We report a pulsed EPR study of the phase relaxation of electron spins bound to phosphorus donors in isotopically purified 29^Si and natural abundance Si single crystals measured at 8 K.Comment: 5 pages, 3 figure

Direct Observation and simulation of ladle pouring behaviour in die casting sleeve

The ladle pouring process is one part of die casting which has the advantages of high speed, good quality and mass production. The molten metal is quickly poured into the sleeve by tilting the ladle, and immediately injected into the die cavity with high speed and high pressure by advancing the plunger. Since the entrapment of air and the generation of solidified layer in the ladle pouring may cause the defects of cast products, it is necessary to simulate the ladle pouring behavior. In the present study, the pouring experiment into the sleeve using water and die casting aluminum alloy JIS-ADC12 are carried out to observe the flow behavior by tilting the ladle. The temperature of the dissolved metal is measured using a thermocouple to investigate heat transfer behavior. The flow behaviors in ladle pouring of water and molten aluminum alloy are simulated using ParticleworksTM of MPS software. The simulation results, when using water are almost the same actual wave behavior. It is difficult to simulate the wave behavior of molten aluminum alloy because there is a difference in wave behavior between water and molten aluminum alloy. On the other hands, it is clear that the molten aluminum alloy is not solidified during wave behavior in the early stage of pouring by the experiments. Therefore, we try to adjust the kinematic viscosity of molten metal and the thermal conductivity of sleeve die. As the result, the wave behavior and temperature of molten aluminum alloy after adjusting the parameters are almost agreed with the actual phenomena. Flow and heat transfer simulation using the MPS method is effective method that ladle pouring of molten aluminum alloy with free surface flow can be simulated accurately

Trio-One: Layering Uncertainty and Lineage on a Conventional DBMS

Trio is a new kind of database system that supports data, uncertainty, and lineage in a fully integrated manner. The first Trio prototype, dubbed Trio-One, is built on top of a conventional DBMS using data and query translation techniques together with a small number of stored procedures. This paper describes Trio-One's translation scheme and system architecture, showing how it efficiently and easily supports the Trio data model and query language

Quantum Nernst effect in a bismuth single crystal

We report a theoretical calculation explaining the quantum Nernst effect observed experimentally in a bismuth single crystal. Generalizing the edge-current picture in two dimensions, we show that the peaks of the Nernst coefficient survive in three dimensions due to a van Hove singularity. We also evaluate the phonon-drag effect on the Nernst coefficient numerically. Our result agrees with the experimental result for a bismuth single crystal.Comment: 4 pages, 4 figures, to be published in Proceedings of ISQM-Tokyo '0

Hydrodynamic interactions of spherical particles in Poiseuille flow between two parallel walls

We study hydrodynamic interactions of spherical particles in incident Poiseuille flow in a channel with infinite planar walls. The particles are suspended in a Newtonian fluid, and creeping-flow conditions are assumed. Numerical results, obtained using our highly accurate Cartesian-representation algorithm [Physica A xxx, {\bf xx}, 2005], are presented for a single sphere, two spheres, and arrays of many spheres. We consider the motion of freely suspended particles as well as the forces and torques acting on particles adsorbed at a wall. We find that the pair hydrodynamic interactions in this wall-bounded system have a complex dependence on the lateral interparticle distance due to the combined effects of the dissipation in the gap between the particle surfaces and the backflow associated with the presence of the walls. For immobile particle pairs we have examined the crossover between several far-field asymptotic regimes corresponding to different relations between the particle separation and the distances of the particles from the walls. We have also shown that the cumulative effect of the far-field flow substantially influences the force distribution in arrays of immobile spheres. Therefore, the far-field contributions must be included in any reliable algorithm for evaluating many-particle hydrodynamic interactions in the parallel-wall geometry.Comment: submitted to Physics of Fluid