53,831 research outputs found
Magnitude and frequency of wind speed shears and associated downdrafts
Data are presented indicating the frequency of occurrence of wind shear and downdrafts together with information on the simultaneous occurrence of these two phenomena. High resolution wind profile measurements recorded at a 150 meter ground winds tower facility were used for the analysis. From instantaneous measurements during horizontal wind speeds of gale-force and below intensity, vertical motion at the 10, 60, and 150 m levels was approximately 60 percent downward and 40 percent upward. At the 18 level the percentages were reversed. Updraft maxima were an order of magnitude or two greater than downdrafts at all levels. Frequency of vertical motion or = 9.7 kts for a year at four levels was 338 occurrences upward and 274 downward. Approximately 90 percent of these updrafts occurred at the 18 m level almost equally during summer and winter, and 65 percent of the downdrafts were at the 150 m level during summer
Orbital magnetic moment and extrinsic spin Hall effect for iron impurity in gold
We report electronic structure calculations of an iron impurity in gold host.
The spin, orbital and dipole magnetic moments were investigated using the
LDA+ correlated band theory. We show that the {\em
around-mean-field}-LDA+ reproduces the XMCD experimental data well and does
not lead to formation of a large orbital moment on the Fe atom. Furthermore,
exact diagonalization of the multi-orbital Anderson impurity model with the
full Coulomb interaction matrix and the spin-orbit coupling is performed in
order to estimate the spin Hall angle. The obtained value suggests that there is no giant extrinsic spin Hall effect due to
scattering on iron impurities in gold.Comment: 5 pages, 2 figure
Valence-band satellite in the ferromagnetic nickel: LDA+DMFT study with exact diagonalization
The valence-band spectrum of the ferromagnetic nickel is calculated using the
LDA+DMFT method. The auxiliary impurity model emerging in the course of the
calculations is discretized and solved with the exact diagonalization, or, more
precisely, with the Lanczos method. Particular emphasis is given to spin
dependence of the valence-band satellite that is observed around 6 eV below the
Fermi level. The calculated satellite is strongly spin polarized in accord with
experimental findings.Comment: REVTeX 4, 8 pages, 5 figure
Human interleukin-1 receptor antagonist is expressed in liver
AbstractUsing PCR and Northern blot analysis, an IL-1 receptor antagonist specific transcript was amplified from HepG2- and liver mRNA, cDNA clones coding for IL-1 receptor antagonist were isolated from a liver cDNA library and sequence comparison revealed complete identity with the secreted, monocytic form of IL-1 receptor antagonist
Corotation Resonance and Diskoseismology Modes of Black Hole Accretion Disks
We demonstrate that the corotation resonance affects only some
non-axisymmetric g-mode oscillations of thin accretion disks, since it is
located within their capture zones. Using a more general (weaker radial WKB
approximation) formulation of the governing equations, such g-modes, treated as
perfect fluid perturbations, are shown to formally diverge at the position of
the corotation resonance. A small amount of viscosity adds a small imaginary
part to the eigenfrequency which has been shown to induce a secular instability
(mode growth) if it acts hydrodynamically. The g-mode corotation resonance
divergence disappears, but the mode magnitude can remain largest at the place
of the corotation resonance. For the known g-modes with moderate values of the
radial mode number and axial mode number (and any vertical mode number), the
corotation resonance lies well outside their trapping region (and inside the
innermost stable circular orbit), so the observationally relevant modes are
unaffected by the resonance. The axisymmetric g-mode has been seen by Reynolds
& Miller in a recent inviscid hydrodynamic accretion disk global numerical
simulation. We also point out that the g-mode eigenfrequencies are
approximately proportional to m for axial mode numbers |m|>0.Comment: 16 pages, no figures. Submitted to The Astrophysical Journa
Persistence of Tripartite Nonlocality for Non-inertial Observers
We consider the behaviour of bipartite and tripartite non-locality between
fermionic entangled states shared by observers, one of whom uniformly
accelerates. We find that while fermionic entanglement persists for arbitrarily
large acceleration, the Bell/CHSH inequalities cannot be violated for
sufficiently large but finite acceleration. However the Svetlichny inequality,
which is a measure of genuine tripartite non-locality, can be violated for any
finite value of the acceleration.Comment: 4 pages, pdflatex, 2 figure
Investigation of three classes of composite materials for space vehicle application
Three classes of composite materials for space vehicle applicatio
Ordered Measurements of Permutationally-Symmetric Qubit Strings
We show that any sequence of measurements on a permutationally-symmetric
(pure or mixed) multi-qubit string leaves the unmeasured qubit substring also
permutationally-symmetric. In addition, we show that the measurement
probabilities for an arbitrary sequence of single-qubit measurements are
independent of how many unmeasured qubits have been lost prior to the
measurement. Our results are valuable for quantum information processing of
indistinguishable particles by post-selection, e.g. in cases where the results
of an experiment are discarded conditioned upon the occurrence of a given event
such as particle loss. Furthermore, our results are important for the design of
adaptive-measurement strategies, e.g. a series of measurements where for each
measurement instance, the measurement basis is chosen depending on prior
measurement results.Comment: 13 page
An Open-Source 7-Axis, Robotic Platform to Enable Dexterous Procedures within CT Scanners
This paper describes the design, manufacture, and performance of a highly
dexterous, low-profile, 7 Degree-of-Freedom (DOF) robotic arm for CT-guided
percutaneous needle biopsy. Direct CT guidance allows physicians to localize
tumours quickly; however, needle insertion is still performed by hand. This
system is mounted to a fully active gantry superior to the patient's head and
teleoperated by a radiologist. Unlike other similar robots, this robot's fully
serial-link approach uses a unique combination of belt and cable drives for
high-transparency and minimal-backlash, allowing for an expansive working area
and numerous approach angles to targets all while maintaining a small in-bore
cross-section of less than . Simulations verified the system's
expansive collision free work-space and ability to hit targets across the
entire chest, as required for lung cancer biopsy. Targeting error is on average
on a teleoperated accuracy task, illustrating the system's sufficient
accuracy to perform biopsy procedures. The system is designed for lung biopsies
due to the large working volume that is required for reaching peripheral lung
lesions, though, with its large working volume and small in-bore
cross-sectional area, the robotic system is effectively a general-purpose
CT-compatible manipulation device for percutaneous procedures. Finally, with
the considerable development time undertaken in designing a precise and
flexible-use system and with the desire to reduce the burden of other
researchers in developing algorithms for image-guided surgery, this system
provides open-access, and to the best of our knowledge, is the first
open-hardware image-guided biopsy robot of its kind.Comment: 8 pages, 9 figures, final submission to IROS 201
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