2,595 research outputs found
MECHANICAL ANALYSIS OF "ARTISTIC AMPLITUDE" OF POSTFLIGHT IN THE HANDSPRING AND SALT0 FORWARD TUCKED VAULT PERFORMED AT THE 1988 OLYMPICS
NMR measurements on obliquely evaporated Co-Cr films
The distribution of the hyperfine fields or the resonance frequencies in metals and alloys obtained by NMR measurements have been known for a long time. Recently, new experimental data have been published about thin films for studying their chemical inhomogeneities. An example is the study on sputtered and evaporated Co-Cr layers. In this paper we report on the compositional distribution of co-evaporated Co-Cr films by using the Co spin-echo NMR technique. For comparison single source evaporated samples of Co-Cr and pure Co as well as two alloyed ribbons (¿bulk¿ samples) have also been measured. Based on the NMR results the local Cr concentration of the ferromagnetic and less ferromagnetic regions are determined. In comparison the data from the co-evaporated films, even at low substrate temperature, have clearly shown the presence of a process-induced compositional separation. This is in qualitative agreement with the magnetic properties of the samples
X-Ray Study of the Outer Region of Abell 2142 with Suzaku
We observed outer regions of a bright cluster of galaxies A2142 with Suzaku.
Temperature and brightness structures were measured out to the virial radius
() with good sensitivity. We confirmed the temperature drop from 9 keV
around the cluster center to about 3.5 keV at , with the density
profile well approximated by the model with . Within
0.4\r_{200}, the entropy profile agrees with , as predicted by the
accretion shock model. The entropy slope becomes flatter in the outer region
and negative around . These features suggest that the intracluster
medium in the outer region is out of thermal equilibrium. Since the relaxation
timescale of electron-ion Coulomb collision is expected to be longer than the
elapsed time after shock heating at , one plausible reason of the low
entropy is the low electron temperature compared to that of ions. Other
possible explanations would be gas clumpiness, turbulence and bulk motions of
ICM\@. We also searched for a warm-hot intergalactic medium around
and set an upper limit on the oxygen line intensity. Assuming a line-of-sight
depth of 2 Mpc and oxygen abundance of 0.1 solar, the upper limit of an
overdensity is calculated to be 280 or 380, depending on the foreground
assumption.Comment: 14 pages, 8 figure
Magmatic focusing to mid-ocean ridges: the role of grain size variability and non-Newtonian viscosity
Melting beneath mid-ocean ridges occurs over a region that is much broader
than the zone of magmatic emplacement to form the oceanic crust. Magma is
focused into this zone by lateral transport. This focusing has typically been
explained by dynamic pressure gradients associated with corner flow, or by a
sub-lithospheric channel sloping upward toward the ridge axis. Here we discuss
a novel mechanism for magmatic focusing: lateral transport driven by gradients
in compaction pressure within the asthenosphere. These gradients arise from the
co-variation of melting rate and compaction viscosity. The compaction
viscosity, in previous models, was given as a function of melt fraction and
temperature. In contrast, we show that the viscosity variations relevant to
melt focusing arise from grain-size variability and non-Newtonian creep. The
asthenospheric distribution of melt fraction predicted by our models provides
an improved ex- planation of the electrical resistivity structure beneath one
location on the East Pacific Rise. More generally, although grain size and
non-Newtonian viscosity are properties of the solid phase, we find that in the
context of mid-ocean ridges, their effect on melt transport is more profound
than their effect on the mantle corner-flow.Comment: 20 pages, 4 figures, 1 tabl
Virtual turning points and bifurcation of Stokes curves for higher order ordinary differential equations
For a higher order linear ordinary differential operator P, its Stokes curve
bifurcates in general when it hits another turning point of P. This phenomenon
is most neatly understandable by taking into account Stokes curves emanating
from virtual turning points, together with those from ordinary turning points.
This understanding of the bifurcation of a Stokes curve plays an important role
in resolving a paradox recently found in the Noumi-Yamada system, a system of
linear differential equations associated with the fourth Painleve equation.Comment: 7 pages, 4 figure
Detection of highly ionized O and Ne absorption lines in the X-ray spectrum of 4U1820-303 in the globular cluster, NGC 6624
We searched for absorption lines of highly ionized O and Ne in the energy
spectra of two Low-mass X-ray binaries, 4U1820-303 in the globular cluster
NGC6624 and Cyg X-2, observed with the Chandra LETG, and detected O VII, O VIII
and Ne IX absorption lines for 4U1820-303. The equivalent width of the O VII K
alpha line was 1.19 +0.47/-0.30 eV (90 % errors) and the significance was 6.5
sigma. Absorption lines were not detected for Cyg X-2 with a 90 % upper limit
on the equivalent width of 1.06 eV for O VII K alpha. The absorption lines
observed in 4U1820-303 are likely due to hot interstellar medium, because O
will be fully photo-ionized if the absorbing column is located close to the
binary system. The velocity dispersion is restricted to b = 200 - 420 km/s from
consistency between O VII K alpha and K beta lines, Ne/O abundance ratio, and H
column density. The average temperature and the O VII density are respectively
estimated to be log(T[K]) = 6.2 - 6.3 and n(OVII) = (0.7 - 2.3) x 10^{-6}
cm^{-3}. The difference of O VII column densities for the two sources may be
connected to the enhancement of the soft X-ray background (SXB) towards the
Galactic bulge region. Using the polytrope model of hot gas to account for the
SXB we corrected for the density gradient and estimated the midplane O VII
density at the solar neighborhood. The scale height of hot gas is then
estimated using the AGN absorption lines. It is suggested that a significant
portion of both the AGN absorption lines and the high-latitude SXB emission
lines can be explained by the hot gas in our Galaxy.Comment: Accepted for publication in ApJ. 7 pages, 9 eps figure
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