Resistively detected nuclear magnetic resonance via a single InSb two-dimensional electron gas at high temperature

We report on the demonstration of the resistively detected nuclear magnetic resonance (RDNMR) of a single InSb two-dimensional electron gas (2DEG) at elevated temperatures up to 4 K. The RDNMR signal of 115In in the simplest pseudospin quantum Hall ferromagnet triggered by a large direct current shows a peak-dip line shape, where the nuclear relaxation time T1 at the peak and the dip is different but almost temperature independent. The large Zeeman, cyclotron, and exchange energy scales of the InSb 2DEG contribute to the persistence of the RDNMR signal at high temperatures.Comment: 11pages,3figure

Ice XII in its second regime of metastability

We present neutron powder diffraction results which give unambiguous evidence for the formation of the recently identified new crystalline ice phase[Lobban et al.,Nature, 391, 268, (1998)], labeled ice XII, at completely different conditions. Ice XII is produced here by compressing hexagonal ice I_h at T = 77, 100, 140 and 160 K up to 1.8 GPa. It can be maintained at ambient pressure in the temperature range 1.5 < T < 135 K. High resolution diffraction is carried out at T = 1.5 K and ambient pressure on ice XII and accurate structural properties are obtained from Rietveld refinement. At T = 140 and 160 K additionally ice III/IX is formed. The increasing amount of ice III/IX with increasing temperature gives an upper limit of T ~ 150 K for the successful formation of ice XII with the presented procedure.Comment: 3 Pages of RevTeX, 3 tables, 3 figures (submitted to Physical Review Letters

Microprobe Analyses of the Potassium-Calcium Distribution Relationship in Predentine

Apex regions of continuously growing incisors of Wistar rats were quickly dissected, shock-frozen in liquid nitrogen-cooled propane, freeze-dried at -80 °C and infiltrated with Spurr\u27s resin . 400nm thick dry sections were cut with a diamond knife on an ultramicrotome . Relatively flat sections were transferred with an eye lash onto collodium coated aluminum grids. They were flattened with a glass stick and by placing another collodi um coated aluminum grid just on top of the first one, exerting a uniform pressure . After carbon coating the sections were observed using the backscattered and secondary electron signals in a scanning microscope. The predentine was analyzed for calcium and potassium with an energy dispersive x-ray analysis system. The xray spectra revealed in the predentine regions with beginning dentine formation, near the apex, an uneven K-distribution with very low as well as more prominent x-ray peaks. The K peaks were always lower than those of calcium. In areas with advanced dentine formation, prominent K-peaks were always observed. They were normally higher than the Ca-peaks up to a distance of 5- 10 µ.m from the dentine border. Closer to the dentine border the K concentration decreased while the Ca-peak increased. This might indicate that (besides Na) K is used to balance the negative charges of the macromolecules till K is replaced by Ca at the onset of apatite crystal formation

Abnormal storm waves in the winter East/Japan Sea: generation process and hindcasting using an atmosphere-wind wave modelling system

Abnormal storm waves cause coastal disasters along the coasts of Korean Peninsula and Japan in the East/Japan Sea (EJS) in winter, arising due to developed low pressures during the East Asia winter monsoon. The generation of these abnormal storm waves during rough sea states were studied and hindcast using an atmosphere-wave coupled modelling system. Wind waves and swell due to developed low pressures were found to be the main components of abnormal storm waves. The meteorological conditions that generate these waves are classified into three patterns based on past literature that describes historical events as well as on numerical modelling. In hindcasting the abnormal storm waves, a bogussing scheme originally designed to simulate a tropical storm in a mesoscale meteorological model was introduced into the modelling system to enhance the resolution of developed low pressures. The modelling results with a bogussing scheme showed improvements in terms of resolved low pressure, surface wind field, and wave characteristics obtained with the wind field as an input

Instability of Myelin Tubes under Dehydration: deswelling of layered cylindrical structures

We report experimental observations of an undulational instability of myelin figures. Motivated by this, we examine theoretically the deformation and possible instability of concentric, cylindrical, multi-lamellar membrane structures. Under conditions of osmotic stress (swelling or dehydration), we find a stable, deformed state in which the layer deformation is given by \delta R ~ r^{\sqrt{B_A/(hB)}}, where B_A is the area compression modulus, B is the inter-layer compression modulus, and h is the repeat distance of layers. Also, above a finite threshold of dehydration (or osmotic stress), we find that the system becomes unstable to undulations, first with a characteristic wavelength of order \sqrt{xi d_0}, where xi is the standard smectic penetration depth and d_0 is the thickness of dehydrated region.Comment: 5 pages + 3 figures [revtex 4

Pulsed UCN production using a Doppler shifter at J-PARC

We have constructed a Doppler-shifter-type pulsed ultra-cold neutron (UCN) source at the Materials and Life Science Experiment Facility (MLF) of the Japan Proton Accelerator Research Complex (J-PARC). Very-cold neutrons (VCNs) with 136-$\mathrm{m/s}$ velocity in a neutron beam supplied by a pulsed neutron source are decelerated by reflection on a m=10 wide-band multilayer mirror, yielding pulsed UCN. The mirror is fixed to the tip of a 2,000-rpm rotating arm moving with 68-$\mathrm{m/s}$ velocity in the same direction as the VCN. The repetition frequency of the pulsed UCN is $8.33~\mathrm{Hz}$ and the time width of the pulse at production is $4.4~\mathrm{ms}$. In order to increase the UCN flux, a supermirror guide, wide-band monochromatic mirrors, focus guides, and a UCN extraction guide have been newly installed or improved. The $1~\mathrm{MW}$-equivalent count rate of the output neutrons with longitudinal wavelengths longer than $58~\mathrm{nm}$ is $1.6 \times 10^{2}~\mathrm{cps}$, while that of the true UCNs is $80~\mathrm{cps}$. The spatial density at production is $1.4~\mathrm{UCN/cm^{3}}$. This new UCN source enables us to research and develop apparatuses necessary for the investigation of the neutron electric dipole moment (nEDM).Comment: 32 pages, 15 fugures. A grammatical error was fixe

A black ring with a rotating 2-sphere

We present a solution of the vacuum Einstein's equations in five dimensions corresponding to a black ring with horizon topology S^1 x S^2 and rotation in the azimuthal direction of the S^2. This solution has a regular horizon up to a conical singularity, which can be placed either inside the ring or at infinity. This singularity arises due to the fact that this black ring is not balanced. In the infinite radius limit we correctly reproduce the Kerr black string, and taking another limit we recover the Myers-Perry black hole with a single angular momentum.Comment: 10 page