5,477 research outputs found
Atomically straight steps on vicinal Si (111) surfaces prepared by step-parallel current in the kink-up direction
We demonstrate that annealing of a vicinal Si(111) surface at about 800 C
with a direct current in the direction that ascends the kinks enhances the
formation of atomically straight step edges over micrometer lengths, while
annealing with a current in the opposite direction does not. Every straight
step edge has the same atomic configuration U(2,0), which is useful as a
template for the formation of a variety of nanostructures. A phenomenological
model based on electromigration of charged mobile atoms explains the observed
current-polarity dependent behavior.Comment: Accepted for publication in Appl. Phys. Lett. Numbers of pages and
figures are 12 and 4, respectivel
Tidally Triggered Star Formation in Close Pairs of Galaxies: Major and Minor Interactions
We study star formation in a sample of 345 galaxies in 167 pairs and compact
groups drawn from the original CfA2 Redshift Survey and from a follow-up search
for companions. We construct our sample with attention to including pairs with
luminosity contrast |\Delta m_R| >= 2. These 57 galaxies with |\Delta m_R| >= 2
provide a set of nearby representative cases of minor interactions, a central
feature of the hierarchical galaxy formation model. Here we report the
redshifts and positions of the 345 galaxies in our sample, and of 136 galaxies
in apparent pairs that are superpositions. In the pairs sample as a whole,
there are strong correlations between the equivalent width of the H\alpha
emission line and the projected spatial and the line-of-sight velocity
separation of the pair. For pairs of small luminosity contrast, |\Delta m_R| <
2, the member galaxies show a correlation between the equivalent width of
H\alpha and the projected spatial separation of the pair. However, for pairs
with large luminosity contrast, |\Delta m_R| >= 2, we detect no correlation
between the equivalent width of H\alpha and the projected spatial separation.
The relative luminosity of the companion galaxy is more important in a
gravitational tidal interaction than the intrinsic luminosity of the galaxy.
Central star formation across the entire pairs sample depends strongly on the
luminosity ratio, |\Delta m_R|, a reasonable proxy for the mass ratio of the
pair; pairs composed of similarly luminous galaxies produce the strongest
bursts of star formation. Pairs with |\Delta m_R| >= 2 rarely have EW(H\alpha)
>~ 70 Ang.Comment: Minor revisions following journal proof
Microstructural influences on stress migration in electroplated Cu metallization
科研費報告書収録論文(課題番号:13450281・基盤研究(B)(2) ・H13~H15/研究代表者:小池, 淳一/超高速LSI用Cu配線におけるボイド形成機構の研究
The 2000 outburst of the recurrent nova CI Aquilae: optical spectroscopy
We present low- and medium resolution spectra of the recurrent nova CI
Aquilae taken at 14 epochs in May and June, 2000. The overall appearance is
similar to other U Sco-type recurrent novae (U Sco, V394 CrA). Medium
resolution (R=7000-10000) hydrogen and iron profiles suggest an early expansion
velocity of 2000-2500 km/s. The H\alpha evolution is followed from Dt = -0.6 d
to +53 d, starting from a nearly Gaussian shape to a double peaked profile
through strong P-Cyg profiles. The interstellar component of the sodium D line
and two diffuse interstellar bands put constraints on the interstellar
reddening which is estimated to be E(B-V)=0.85\pm0.3. The available visual and
CCD-V observations are used to determine t0,t2 and t3. The resulting parameters
are: t0=2451669.5\pm0.1, t2=30\pm1 d, t3=36\pm1 d. The recent lightcurve is
found to be generally similar to that observed in 1917 with departures as large
as 1-2 mag in certain phases. This behaviour is also typical for the U Sco
subclass.Comment: 8 pages, 7 figures, accepted for publication in A&
A Theoretical Light-Curve Model for the Recurrent Nova V394 Coronae Austrinae
A theoretical light curve for the 1987 outburst of V394 Coronae Austrinae
(V394 CrA) is modeled to obtain various physical parameters of this recurrent
nova. We then apply the same set of parametersto a quiescent phase and confirm
that these parameters give a unified picture of the binary. The early visual
light curve (1-10 days after the optical maximum) is well reproduced by a
thermonuclear runaway model on a very massive WD close to the Chandrasekhar
limit (1.37 +- 0.01 M_sun). The ensuing plateau phase (10-30 days) is also
reproduced by the combination of a slightly irradiated MS and a fully
irradiated flaring-up disk with a radius ~1.4 times the Roche lobe size. The
best fit parameters are the WD mass 1.37 M_sun, the companion mass 1.5 M_sun
(0.8-2.0 M_sun is acceptable), the inclination angle of the orbit i~65-68
degree, and the flaring-up rim ~0.30 times the disk radius. The envelope mass
at the optical peak is estimated to be ~6 x 10^{-6} M_sun, which indicates an
average mass accretion rate of 1.5 x 10^{-7} M_sun yr^{-1} during the quiescent
phase between the 1949 and 1987 outbursts. In the quiescent phase, the observed
light curve can be reproduced with a disk size of 0.7 times the Roche lobe size
and a rather slim thickness of 0.05 times the accretion disk size at the rim.
About 0.5 mag sinusoidal variation of the light curve requires the mass
accretion rate higher than ~1.0 x 10^{-7} M_sun yr^{-1}, which is consistent
with the above estimation from the 1987 outburst. These newly obtained
quantities are exactly the same as those predicted in a new progenitor model of
Type Ia supernovae.Comment: 9 pages including 4 figures, to appear in the Astrophysical Journal,
Part
Spin dependent recombination based magnetic resonance spectroscopy of bismuth donor spins in silicon at low magnetic fields
Low-field (6-110 mT) magnetic resonance of bismuth (Bi) donors in silicon has
been observed by monitoring the change in photoconductivity induced by spin
dependent recombination. The spectra at various resonance frequencies show
signal intensity distributions drastically different from that observed in
conventional electron paramagnetic resonance, attributed to different
recombination rates for the forty possible combinations of spin states of a
pair of a Bi donor and a paramagnetic recombination center. An excellent
tunability of Bi excitation energy for the future coupling with superconducting
flux qubits at low fields has been demonstrated.Comment: 5 pages, 4 figure
Self-consistent picture of the mass ejection from a one second-long binary neutron star merger leaving a short-lived remnant in general-relativistic neutrino-radiation magnetohydrodynamic simulation
We perform a general-relativistic neutrino-radiation magnetohydrodynamicsimulation of a one second-long binary neutron star merger on Japanesesupercomputer Fugaku using about million CPU hours with CPUs. Weconsider an asymmetric binary neutron star merger with masses of and and a `soft' equation of state SFHo. It results in a short-livedremnant with the lifetime of \,s, and subsequent massive torusformation with the mass of after the remnant collapses toa black hole. For the first time, we confirm that after the dynamical massejection, which drives the fast tail and mildly relativistic components, thepost-merger mass ejection from the massive torus takes place due to themagnetorotational instability-driven turbulent viscosity and the two ejectacomponents are seen in the distributions of the electron fraction and velocitywith distinct features.<br
Effective combination therapy using interferon-gamma and interleukin-2 for disseminated Mycobacterium avium complex infection in a pediatric patient with AIDS
© 2006 by [The University of Chicago Press ]ArticleCLINICAL INFECTIOUS DISEASES. 41(11): E104-E106 (2005)journal articl
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