17,872 research outputs found
Partially Unbiased Entangled Bases
In this contribution we group the operator basis for d^2 dimensional Hilbert
space in a way that enables us to relate bases of entangled states with single
particle mutually unbiased state bases (MUB), each in dimensionality d. We
utilize these sets of operators to show that an arbitrary density matrix for
this d^2 dimensional Hilbert space system is analyzed by via d^2+d+1
measurements, d^2-d of which involve those entangled states that we associate
with MUB of the d-dimensional single particle constituents. The number
lies in the middle of the number of measurements needed for bipartite
state reconstruction with two-particle MUB (d^2+1) and those needed by
single-particle MUB [(d^2+1)^2].Comment: 5 page
Optical links in the angle-data assembly of the 70-meter antennas
In the precision-pointing mode the 70 meter antennas utilize an optical link provided by an autocollimator. In an effort to improve reliability and performance, commercial instruments were evaluated as replacement candidates, and upgraded versions of the existing instruments were designed and tested. The latter were selected for the Neptune encounter, but commercial instruments with digital output show promise of significant performance improvement for the post-encounter period
A general low frequency acoustic radiation capability for NASTRAN
A new capability called NASHUA is described for calculating the radiated acoustic sound pressure field exterior to a harmonically-excited arbitrary submerged 3-D elastic structure. The surface fluid pressures and velocities are first calculated by coupling a NASTRAN finite element model of the structure with a discretized form of the Helmholtz surface integral equation for the exterior fluid. After the fluid impedance is calculated, most of the required matrix operations are performed using the general matrix manipulation package (DMAP) available in NASTRAN. Far field radiated pressures are then calculated from the surface solution using the Helmholtz exterior integral equation. Other output quantities include the maximum sound pressure levels in each of the three coordinate planes, the rms and average surface pressures and normal velocities, the total radiated power and the radiation efficiency. The overall approach is illustrated and validated using known analytic solutions for submerged spherical shells subjected to both uniform and nonuniform applied loads
MAPK phosphatase-1 represents a novel antiinflammatory target of glucocorticoids in the human endothelium
Glucocorticoids are well-established anti-
inflammatory drugs thought to mainly act by inhibition of proinflammatory transcription factors like NF-κB. In recent years, however, transcription factorindependent mechanisms of glucocorticoid action have been proposed, namely the influence on MAPK pathways. Here we identify MAPK phosphatase-1 (MKP-1) as a pivotal mediator of the anti-inflammatory action of glucocorticoids in the human endothelium. We applied dexamethasone (Dex) to TNF-α-activated human endothelial cells and used the adhesion molecule E-selectin as inflammatory read-out parameter. Dex is known to reduce the expression of E-selectin, which is largely regulated by NF-κB. Here, we communicate that Dex at low concentrations (1–100 nM) markedly attenuates E-selectin expression without affecting NF-κB. Importantly, Dex is able to increase the expression of MKP-1, which causes an inactivation of TNF-α-induced p38 MAPK and mediates inhibition of E-selectin expression. In endothelial MKP-1ˉ/ˉ cells differentiated from MKP-1ˉ/ˉ embryonic stem cells and in MKP-1-silenced human endothelial cells, Dex did not inhibit TNF-α-evoked E-selectin expression. Thus, our findings introduce MKP-1 as a novel and crucial mediator of the anti-inflammatory action of glucocorticoids at low concentrations in the human endothelium and highlight MKP-1 as an important and promising antiinflammatory drug target
Some remarks on the visible points of a lattice
We comment on the set of visible points of a lattice and its Fourier
transform, thus continuing and generalizing previous work by Schroeder and
Mosseri. A closed formula in terms of Dirichlet series is obtained for the
Bragg part of the Fourier transform. We compare this calculation with the
outcome of an optical Fourier transform of the visible points of the 2D square
lattice.Comment: 9 pages, 3 eps-figures, 1 jpeg-figure; updated version; another
article (by M. Baake, R. V. Moody and P. A. B. Pleasants) with the complete
solution of the spectral problem will follow soon (see math.MG/9906132
Multifractal eigenstates of quantum chaos and the Thue-Morse sequence
We analyze certain eigenstates of the quantum baker's map and demonstrate,
using the Walsh-Hadamard transform, the emergence of the ubiquitous Thue-Morse
sequence, a simple sequence that is at the border between quasi-periodicity and
chaos, and hence is a good paradigm for quantum chaotic states. We show a
family of states that are also simply related to Thue-Morse sequence, and are
strongly scarred by short periodic orbits and their homoclinic excursions. We
give approximate expressions for these states and provide evidence that these
and other generic states are multifractal.Comment: Substantially modified from the original, worth a second download. To
appear in Phys. Rev. E as a Rapid Communicatio
Topoisomerase activity assays in Neurospora
DNA topoisomerases are enzymes capable of altering the topological conformation of DNA by inducing transient single (Topoisomerase I) and double strand (Topoisomerase II) breaks
Photoelasticity of sodium silicate glass from first principles
Based on density-functional perturbation theory we have computed the
photoelastic tensor of a model of sodium silicate glass of composition
(NaO)(SiO) (NS3). The model (containig 84 atoms) is
obtained by quenching from the melt in combined classical and Car-Parrinello
molecular dynamics simulations. The calculated photoelastic coefficients are in
good agreement with experimental data. In particular, the calculation
reproduces quantitatively the decrease of the photoelastic response induced by
the insertion of Na, as measured experimentally.
The extension to NS3 of a phenomenological model developed in a previous work
for pure a-SiO indicates that the modulation upon strain of other
structural parameters besides the SiOSi angles must be invoked to explain the
change in the photoelstic response induced by Na
The thermodynamics of urban population flows
Orderliness, reflected via mathematical laws, is encountered in different
frameworks involving social groups. Here we show that a thermodynamics can be
constructed that macroscopically describes urban population flows. Microscopic
dynamic equations and simulations with random walkers underlie the macroscopic
approach. Our results might be regarded, via suitable analogies, as a step
towards building an explicit social thermodynamics
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