966,289 research outputs found
Mean curvature flow of monotone Lagrangian submanifolds
We use holomorphic disks to describe the formation of singularities in the
mean curvature flow of monotone Lagrangian submanifolds in .Comment: 37 pages, 3 figure
Spin accumulation created electrically in an n-type germanium channel using Schottky tunnel contacts
Using high-quality FeSi/-Ge Schottky-tunnel-barrier contacts, we
study spin accumulation in an -type germanium (-Ge) channel. In the
three- or two-terminal voltage measurements with low bias current conditions at
50 K, Hanle-effect signals are clearly detected only at a forward-biased
contact. These are reliable evidence for electrical detection of the spin
accumulation created in the -Ge channel. The estimated spin lifetime in
-Ge at 50 K is one order of magnitude shorter than those in -Si reported
recently. The magnitude of the spin signals cannot be explained by the commonly
used spin diffusion model. We discuss a possible origin of the difference
between experimental data and theoretical values.Comment: 4 pages, 3 figures, To appear in J. Appl. Phy
Three-dimensional physics and the pressure of hot QCD
We update Monte Carlo simulations of the three-dimensional SU(3) + adjoint
Higgs theory, by extrapolating carefully to the infinite volume and continuum
limits, in order to estimate the contribution of the infrared modes to the
pressure of hot QCD. The sum of infrared contributions beyond the known 4-loop
order turns out to be a smooth function, of a reasonable magnitude and specific
sign. Unfortunately, adding this function to the known 4-loop terms does not
improve the match to four-dimensional lattice data, in spite of the fact that
other quantities, such as correlation lengths, spatial string tension, or quark
number susceptibilities, work well within the same setup. We outline possible
ways to reduce the mismatch.Comment: 14 page
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Seasonal variations of atmospheric C2-C7 nonmethane hydrocarbons in Tokyo
Eighteen C2-C7 NMHCs (nonmethane hydrocarbons) were measured hourly during the Integrated Measurement Program for Aerosol and Oxidant Chemistry in Tokyo (IMPACT) measurement campaigns conducted in central Tokyo during four different periods (summer/autumn of 2003 and winter/summer of 2004). The ambient atmospheric concentrations of NMHCs showed an inverse correlation with wind speed and mixing height and were significantly affected by mesoscale weather conditions. The mixing ratio of isoprene tightly correlated with solar flux and temperature in summer, as it was dominantly emitted by the local vegetation. All the observed NMHCs except isoprene showed high correlation with each other in winter (r2 > 0.5), suggesting concurrent accumulation under stagnant condition and common sources. Emission ratios were calculated on the basis of the correlation with carbon monoxide and ethyne. Compared to the typical winter NMEC composition, during summer there was a significant increase (up to 7 times higher than wintertime) of C4-C5 alkanes from ftiel evaporation; of C2-C3 alkenes, n-hexane and benzene from chemical industry; and of toluene from local manufacturers, reflecting the temperature dependence of these evaporative emissions. In addition to the online measurements in Tokyo, canister sampling at a suburban site (Kisai) followed by multidimensional GC analyses was conducted during the summer campaign in 2004. The atmospheric concentrations of longer-lived compounds (≥ several days) at Kisai showed the buildup under sea breeze circulation. The average ambient, concentration of toluene was 2 times higher than that in central Tokyo, likely because of substantial emissions from local industries as reported in the prefectural statistics. Copyright 2007 by the American Geophysical Union
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