6,969 research outputs found
Projectile Excitations in Reactions
It has recently been proven from measurements of the spin-transfer
coefficients and that there is a small but non-vanishing
component , in the inclusive reaction
cross section . It is shown that the dominant part of the measured
can be explained in terms of the projectile excitation
mechanism. An estimate is further made of contributions to from
s-wave rescattering process. It is found that s-wave rescattering contribution
is much smaller than the contribution coming from projectile
excitation mechanism. The addition of s-wave rescattering contribution to the
dominant part, however, improves the fit to the data.Comment: 9 pages, Revtex, figures can be obtained upon reques
Continual variations in the high energy X-ray flux from Sco X-1
Balloon X ray observations of intensity fluctuations in Sco X-
Schwarzschild Atmospheric Processes: A Classical Path to the Quantum
We develop some classical descriptions for processes in the Schwarzschild
string atmosphere. These processes suggest relationships between macroscopic
and microscopic scales. The classical descriptions developed in this essay
highlight the fundamental quantum nature of the Schwarzschild atmospheric
processes.Comment: to appear in Gen. Rel. Gra
Dimension in a Radiative Stellar Atmosphere
Dimensional scales are examined in an extended 3+1 Vaidya atmosphere
surrounding a Schwarzschild source. At one scale, the Vaidya null fluid
vanishes and the spacetime contains only a single spherical 2-surface. Both of
these behaviors can be addressed by including higher dimensions in the
spacetime metric.Comment: to appear in Gen. Rel. Gra
Noise Effects on the Complex Patterns of Abnormal Heartbeats
Patients at high risk for sudden death often exhibit complex heart rhythms in
which abnormal heartbeats are interspersed with normal heartbeats. We analyze
such a complex rhythm in a single patient over a 12-hour period and show that
the rhythm can be described by a theoretical model consisting of two
interacting oscillators with stochastic elements. By varying the magnitude of
the noise, we show that for an intermediate level of noise, the model gives
best agreement with key statistical features of the dynamics.Comment: 4 pages, 4 figures, RevTe
Giant complex odontoma of the maxillary antrum
Complex odontomas are rare benign jaw neoplasms. generally small and asymptomatic. We present an unusual case of a giant complex odontoma which completely filled the maxillary antrum, resulting in elevation of the orbit and facial asymmetry
HV 11423: The Coolest Supergiant in the SMC
We call attention to the fact that one of the brightest red supergiants in
the SMC has recently changed its spectral type from K0-1 I (December 2004) to
M4 I (December 2005) and back to K0-1 I (September 2006). An archival spectrum
from the Very Large Telescope reveals that the star was even cooler (M4.5-M5 I)
in December 2001. By contrast, the star was observed to be an M0 I in both
October 1978 and October 1979. The M4-5 I spectral types is by far the latest
type seen for an SMC supergiant, and its temperature in that state places it
well beyond the Hayashi limit into a region of the H-R diagram where the star
should not be in hydrostatic equilibrium. The star is variable by nearly 2 mag
in V, but essentially constant in K. Our modeling of its spectral energy
distribution shows that the visual extinction has varied during this time, but
that the star has remained essentially constant in bolometric luminosity. We
suggest that the star is currently undergoing a period of intense instability,
with its effective temperature changing from 4300 K to 3300 K on the time-scale
of months. It has one of the highest 12-micron fluxes of any RSG in the SMC,
and we suggest that the variability at V is due primarily to changes in
effective temperature, and secondly, due to changes in the local extinction due
to creation and dissipation of circumstellar dust. We speculate that the star
may be nearing the end of its life.Comment: Accepted by the Astrophysical Journa
Levi-Civita cylinders with fractional angular deficit
The angular deficit factor in the Levi-Civita vacuum metric has been
parametrized using a Riemann-Liouville fractional integral. This introduces a
new parameter into the general relativistic cylinder description, the
fractional index {\alpha}. When the fractional index is continued into the
negative {\alpha} region, new behavior is found in the Gott-Hiscock cylinder
and in an Israel shell.Comment: 5 figure
A Characterisation of Strong Wave Tails in Curved Space-Times
A characterisation of when wave tails are strong is proposed. The existence
of a curvature induced tail (i.e. a Green's function term whose support
includes the interior of the light-cone) is commonly understood to cause
backscattering of the field governed by the relevant wave equation. Strong
tails are characterised as those for which the purely radiative part of the
field is backscattered. With this definition, it is shown that electromagnetic
waves in asymptotically flat space-times and fields governed by tail-free
propagation have weak tails, but minimally coupled scalar fields in a
cosmological scenario have strong tails.Comment: 17 pages, Revtex, to appear in Classical and Quantum Gravit
Morphology of the 12-micron Seyfert Galaxies: II. Optical and Near-Infrared Image Atlas
We present 263 optical and near-infrared (NIR) images for 42 Seyfert 1s and
48 Seyfert 2s, selected from the Extended 12-micron Galaxy Sample.
Elliptically-averaged profiles are derived from the images, and isophotal radii
and magnitudes are calculated from these. We also report virtual aperture
photometry, that judging from comparison with previous work, is accurate to
roughly 0.05mag in the optical, and 0.07mag in the NIR. Our B-band isophotal
magnitude and radii, obtained from ellipse fitting, are in good agreement with
those of RC3. When compared with the B band, V, I, J, and K isophotal diameters
show that the colors in the outer regions of Seyferts are consistent with the
colors of normal spirals. Differences in the integrated isophotal colors and
comparison with a simple model show that the active nucleus+bulge is stronger
and redder in the NIR than in the optical. Finally, roughly estimated Seyfert
disk surface brightnesses are significantly brighter in B and K than those in
normal spirals of similar morphological type.Comment: 17 pgs including figures; Table 2 is a separate file. Complete Figure
1 is available by contacting the authors. Accepted for publication in ApJ
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