458 research outputs found
Administrative Regulations - Medicare - Medicare Provider Reimbursement Manual - Defeasance Losses
The United States Supreme Court held that the Secretary of Health and Human Services is not bound to apply generally accepted accounting principles in calculating the amount which health care providers should receive under Medicare for reimbursement of bond defeasance losses.
Shalala v. Guernsey Memorial Hospital, 115 S. Ct. 1232 (1995)
Transient jets in the symbiotic prototype Z Andromedae
We present development of the collimated bipolar jets from the symbiotic
prototype Z And that appeared and disappeared during its 2006 outburst. In 2006
July Z And reached its historical maximum at U ~ 8.0. During this period, rapid
photometric variations with Dm ~ 0.06 mag on the timescale of hours developed.
Simultaneously, high-velocity satellite components appeared on both sides of
the H-alpha and H-beta emission line profiles. They were launched
asymmetrically with the red/blue velocity ratio of 1.2 - 1.3. From about
mid-August they became symmetric. Their spectral properties indicated ejection
of bipolar jets collimated within an average opening angle of 6.1 degrees. We
estimated average outflow rate via jets to dM(jet)/dt ~
2xE10-6(R(jet)/1AU)**(1/2) M(Sun)/year, during their August - September
maximum, which corresponds to the emitting mass in jets, M(jet, emitting) ~
6xE-10(Rjet)/1AU)^{3/2} M(Sun). During their lifetime, the jets released the
total mass of M(jet, total) approx 7.4x1E-7 M(Sun). Evolution in the rapid
photometric variability and asymmetric ejection of jets around the optical
maximum can be explained by a disruption of the inner parts of the disk caused
by radiation-induced warping of the disk.Comment: 31 pages, 9 figures, 2 tables, accepted for Ap
Kelvin probe characterization of buried graphitic microchannels in single-crystal diamond
In this work, we present an investigation by Kelvin Probe Microscopy (KPM) of
buried graphitic microchannels fabricated in single-crystal diamond by direct
MeV ion microbeam writing. Metal deposition of variable-thickness masks was
adopted to implant channels with emerging endpoints and high temperature
annealing was performed in order to induce the graphitization of the
highly-damaged buried region. When an electrical current was flowing through
the biased buried channel, the structure was clearly evidenced by KPM maps of
the electrical potential of the surface region overlying the channel at
increasing distances from the grounded electrode. The KPM profiling shows
regions of opposite contrast located at different distances from the endpoints
of the channel. This effect is attributed to the different electrical
conduction properties of the surface and of the buried graphitic layer. The
model adopted to interpret these KPM maps and profiles proved to be suitable
for the electronic characterization of buried conductive channels, providing a
non-invasive method to measure the local resistivity with a micrometer
resolution. The results demonstrate the potential of the technique as a
powerful diagnostic tool to monitor the functionality of all-carbon
graphite/diamond devices to be fabricated by MeV ion beam lithography.Comment: 21 pages, 5 figure
HOMOGENEOUS RIEMANNIAN MANIFOLDS WITH NON-TRIVIAL NULLITY
We develop a general theory for irreducible homogeneous spaces M = G/H, in relation to the nullity distribution Μ of their curvature tensor. We construct natural invariant (different and increasing) distributions associated with the nullity, that give a deep insight of such spaces. In particular, there must exist an order-two transvection, not in the nullity, with null Jacobi operator. This fact was very important for finding out the first homogeneous examples with non-trivial nullity, i.e., where the nullity distribution is not parallel. Moreover, we construct irreducible examples of conullity k = 3, the smallest possible, in any dimension. None of our examples admit a quotient of finite volume. We also proved that H is trivial and G is solvable if k = 3. Another of our main results is that the leaves, i.e., the integral manifolds, of the nullity are closed (we used a rather delicate argument). This implies that M is a Euclidean affine bundle over the quotient by the leaves of Μ. Moreover, we prove that Μ℠defines a metric connection on this bundle with transitive holonomy or, equivalently, Μ℠is completely non-integrable (this is not in general true for an arbitrary autoparallel and at invariant distribution). We also found some general obstruction for the existence of non-trivial nullity: e.g., if G is reductive (in particular, if M is compact), or if G is two-step nilpotent
Angle resolved IBIC analysis of 4H-SiC Schottky diodes
We present a new experimental procedure based on the ion beam induced charge collection (IBIC) to characterise semiconductor detectors and devices. It consists in measuring the charge collection efficiency (q) as a function of the angle of incidence (eta) of a strongly penetrating MeV ion beam focussed onto a partially depleted semiconductor detector. The unidimensional model based on the drift-diffusion model derived from the Shockley-Ramo-Gunn's theorem gives the theoretical background to fit the eta(alpha) curve and to estimate both the extension of the depletion layer, the dead layer thickness and the minority carrier diffusion length. To illustrate the analytical capability of this technique, a 2 MeV proton beam was focussed at different incident angles onto a 4H-SiC Schottky diode; the experimental results and the theoretical approach are presented and discussed. (c) 2006 Published by Elsevier B.V
High-Resolution Spectroscopy in Tr37: Gas Accretion Evolution in Evolved Dusty Disks
Using the Hectochelle multifiber spectrograph, we have obtained
high-resolution (R~34,000) spectra in the Halpha region for a large number of
stars in the 4 Myr-old cluster Tr 37, containing 146 previously known members
and 26 newly identified ones. We present the Halpha line profiles of all
members, compare them to our IR observations of dusty disks (2MASS/JHK + IRAC +
MIPS 24 micron), use the radial velocities as a membership criterion, and
calculate the rotational velocities. We find a good correlation between the
accretion-broadened profiles and the presence of protoplanetary disks, noting
that a small fraction of the accreting stars presents broad profiles with
Halpha equivalent widths smaller than the canonical limit separating CTTS and
WTTS. The number of strong accretors appears to be lower than in younger
regions, and a large number of CTTS have very small accretion rates
(dM/dt<10^{-9} Msun/yr). Taking into account that the spectral energy
distributions are consistent with dust evolution (grain growth/settling) in the
innermost disk, this suggests a parallel evolution of the dusty and gaseous
components. We also observe that about half of the "transition objects" (stars
with no IR excesses at wavelengths shorter than ~6 micron) do not show any
signs of active accretion, whereas the other half is accreting with accretion
rates <10^{-9} Msun/yr. These zero or very low accretion rates reveal important
gas evolution and/or gas depletion in the innermost disk, which could be
related to grain growth up to planetesimal or even planet sizes. Finally, we
examine the rotational velocities of accreting and non accreting stars, finding
no significant differences that could indicate disk locking at these ages.Comment: 51 pages, 13 (reduced resolution) figures, 2 tables. AJ in pres
The symbiotic star CH Cygni â II. The ejecta from the 1998-2000 active phase
We present Hubble Space Telescope (HST) imaging, a Very Large Array (VLA) radio map (4.74 GHz), optical high-resolution (echelle) spectroscopy and UBV photoelectric photometry of the symbiotic star CH Cyg obtained during its 1998â2000 active phase. The HST imaging, taken during eclipse, shows the central stars are embedded in a nebula extending to 620 ± 150 au for a distance of 270 ± 66 pc. The inner nebula is strongly influenced by the onset of activity and associated outflow in 1998. The surface brightness contours of the contemporaneous radio VLA observation agree well with HST images. Photometric observations of the broad 1999 U-minimum suggest that it is due to the eclipse of the active hot component by the giant on the long-period (14.5 yr) outer orbit. We also find that the onset of the 1998 and the 1992 active periods occur at the same orbital phase of the inner binary. Spectroscopic observations reveal two types of outflow from the active star: a high-velocity (>1200 km sâ1) hot star wind sporadically alternating with a more massive outflow indicated by P-Cygni-like profiles. We present evidence connecting the extended nebulosity with the high-velocity shocked outflow, and hence the activity in the central binary
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