29,664 research outputs found
Kinematics of Red Variables in the Solar Neighborhood I. Basic Data Obtained by an SiO Maser Survey
In order to study the streaming motions of miras in the Solar neighborhood,
we newly surveyed 379 red variables in the SiO maser lines at 42.821 and 43.122
GHz with the Nobeyama 45m radio telescope. Accurate radial velocities were
obtained for 229 (220 new) detected stars. The sample is selected from optical
variables found by new automated surveys: the Northern Sky Variability Survey
and the All Sky Automated Survey. The new sample consists of the "bluer"
objects compared with those observed in the previous SiO surveys. The distances
to the objects are estimated using the period-luminosity relation, and they are
mostly less than 3 kpc from the Sun. The longitude-velocity diagram reveals
three prominent groups of stars deviant from the circular Galactic rotation
with a flat rotation curve. In addition to the Hercules group of stars which
was studied before, we found two new deviant groups: one toward the Perseus arm
and the other toward the Sagittarius arm. These two groups both exhibit
anomalous motions toward the Galactic center, which seem to be consistent with
the noncircular motions of these spiral arms found in the recent VLBI
proper-motion measurements for maser gas clumps.Comment: PASJ 64 no.1 (2012 Feb. 25 issue) in press. A full version including
  Fig. 8a-m, and Fig. 9 are available at
  http://www.nro.nao.ac.jp/~lib_pub/report/data/no680.pd
Mechanism of Ambipolar Field-Effect Carrier Injections in One-Dimensional Mott Insulators
To clarify the mechanism of recently reported, ambipolar carrier injections
into quasi-one-dimensional Mott insulators on which field-effect transistors
are fabricated, we employ the one-dimensional Hubbard model attached to a
tight-binding model for source and drain electrodes. To take account of the
formation of Schottky barriers, we add scalar and vector potentials, which
satisfy the Poisson equation with boundary values depending on the drain
voltage, the gate bias, and the work-function difference. The current-voltage
characteristics are obtained by solving the time-dependent Schr\"odinger
equation in the unrestricted Hartree-Fock approximation. Its validity is
discussed with the help of the Lanczos method applied to small systems. We find
generally ambipolar carrier injections in Mott insulators even if the work
function of the crystal is quite different from that of the electrodes. They
result from balancing the correlation effect with the barrier effect. For the
gate-bias polarity with higher Schottky barriers, the correlation effect is
weakened accordingly, owing to collective transport in the one-dimensional
correlated electron systems.Comment: 21 pages, 10 figures, to appear in J. Phys. Soc. Jp
Proton-neutron alignment in the yrast states of Ge and Ge
The Ge and Ge nuclei are studied by means of the shell model
with the extended  Hamiltonian, which succeeds in reproducing
experimentally observed energy levels, moments of inertia and other properties.
The investigation using the reliable wave-functions predicts T=0, J=9
one-proton-one-neutron () alignment in the  orbit, at high spins
(,  and ) in these  even-even nuclei. It
is shown that a series of the even- positive-parity yrast states (observed
up to  for Ge) consists of the ground-state band and successive
three bands with different types of particle alignments (two-neutron, ,
two-proton-two-neutron) in the  orbit.Comment: 4 pages, 5 figures, to be published in Pyhs. Rev. 
Evaluation of the effects of a freeze/thaw environment on cellular glass
Using the evaluation criteria of water vapor permeability and conformability, a protective butylrubber/silicone conformal coating system was selected for use on Foamglas substrates in a freeze/thaw environment. The selection of a specific freeze/thaw cycle which closely models field conditions is discussed. A sampling plan is described which allows independent evaluation of the effects of conformal coatings, cycle number and location within the environmental chamber. The results of visual examination, measurement of density, modulus of rupture and Young's modulus are reported. Based upon statistical evaluation of the experimental results, it is concluded that no degradation in mechanical properties of either coated or uncoated Foamglas occurred within the duration of the test (53 freeze/thaw cycles)
Structure of isomeric states in 66As and 67As
Strong residual correlations between neutrons and protons in N ~ Z systems
can lead to unusual structure. Using the spherical shell model, we show that a
low-excitation shape isomer can occur in the odd-odd N=Z nucleus 66As. This
extends the picture of shape coexistence beyond even-even nuclei. Furthermore,
it is demonstrated that in 66As and in the N=Z+1 nucleus 67As, a new type of
isomer, which we term j-isomer, can be formed. The underlying mechanism for the
isomerism formation is structure change in the isomeric states, which involves
either an alignment of a neutron-proton pair from the high-j intruder orbitals,
or a simultaneous occupation of these neutron and proton high-j orbitals.Comment: 11 pages, 2 figure
An Estimation Method for the Emission Accounting Table of Global Agricultural Activities
This paper describes an estimation method to develop an emission accounting table of global agricultural activities which consists of accounting tables including agricultural commodity flows from production to consumption, GHG emissions and agricultural waste etc.. Material and monetary flows related with agricultural commodities are estimated by using reported information such as production, trade and cosumption from published statistics. In our calculation, the table covers 94 countries and 12 regions in the world from 1971 to 2000. These calculations are conducted to extract most plausible estimates which minimize differences between estimated data and reported data subjected to several constraints on the accounting systems. In our estimation, 47.4% and 72.2% of all estimated values are in 0.95-1.05% range and 0.80-1.20% range of reported value, respectvely. We found a part of outliers in the existing data was modified. We clarified that total CH4 and N2O emission is estimated to have been 2450 MtCO2eq and 131 MtCO2eq in 1971 and they are estimated to have increased to 3140 MtCO2eq and 2220 MtCO2eq in 2000
Recombination kinetics of a dense electron-hole plasma in strontium titanate
We investigated the nanosecond-scale time decay of the blue-green light
emitted by nominally pure SrTiO following the absorption of an intense
picosecond laser pulse generating a high density of electron-hole pairs. Two
independent components are identified in the fluorescence signal that show a
different dynamics with varying excitation intensity, and which can be
respectively modeled as a bimolecular and unimolecolar process. An
interpretation of the observed recombination kinetics in terms of interacting
electron and hole polarons is proposed
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