37,212 research outputs found
Nimbus 6 Doppler processing using the Fairbanks calibration platform
A weighted least squares processor is examined. Research conducted in support of the NASA satellite aided Search and Rescue program is presented. An estimated NIMBUS 6 ephemeris, accurate to 1.5-2.5 km and 0.5-2.5 m/s relative to a reference orbit, is obtained during the three day signal transmission period. This suggests updating the knowledge of the relay satellite ephemeris by one reference beacon is needed during the Search and Rescue demonstration
Carleman estimates and absence of embedded eigenvalues
Let L be a Schroedinger operator with potential W in L^{(n+1)/2}. We prove
that there is no embedded eigenvalue. The main tool is an Lp Carleman type
estimate, which builds on delicate dispersive estimates established in a
previous paper. The arguments extend to variable coefficient operators with
long range potentials and with gradient potentials.Comment: 26 page
Current Induced Excitations in Cu/Co/Cu Single Ferromagnetic Layer Nanopillars
Current-induced magnetic excitations in Cu/Co/Cu single layer nanopillars
(~50 nm in diameter) have been studied experimentally as a function of Co layer
thickness at low temperatures for large applied fields perpendicular to the
layers. For asymmetric junctions current induced excitations are observed at
high current densities for only one polarity of the current and are absent at
the same current densities in symmetric junctions. These observations confirm
recent predictions of spin-transfer torque induced spin wave excitations in
single layer junctions with a strong asymmetry in the spin accumulation in the
leads.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
The QCD phase diagram and statistics friendly distributions
The preliminary STAR data for proton cumulants for central collisions at s=7.7GeV component proton multiplicity distribution. We show that this two-component distribution is statistics friendly in that factorial cumulants of surprisingly high orders may be extracted with a relatively small number of events. As a consequence the two-component model can be tested and verified right now with the presently available STAR data from the first phase of the RHIC beam energy scan
InSb charge coupled infrared imaging device: The 20 element linear imager
The design and fabrication of the 8585 InSb charge coupled infrared imaging device (CCIRID) chip are reported. The InSb material characteristics are described along with mask and process modifications. Test results for the 2- and 20-element CCIRID's are discussed, including gate oxide characteristics, charge transfer efficiency, optical mode of operation, and development of the surface potential diagram
A double coset ansatz for integrability in AdS/CFT
We give a proof that the expected counting of strings attached to giant
graviton branes in AdS_5 x S^5, as constrained by the Gauss Law, matches the
dimension spanned by the expected dual operators in the gauge theory. The
counting of string-brane configurations is formulated as a graph counting
problem, which can be expressed as the number of points on a double coset
involving permutation groups. Fourier transformation on the double coset
suggests an ansatz for the diagonalization of the one-loop dilatation operator
in this sector of strings attached to giant graviton branes. The ansatz agrees
with and extends recent results which have found the dynamics of open string
excitations of giants to be given by harmonic oscillators. We prove that it
provides the conjectured diagonalization leading to harmonic oscillators.Comment: 33 pages, 3 figures; v2: references adde
Interaction-assisted propagation of Coulomb-correlated electron-hole pairs in disordered semiconductors
A two-band model of a disordered semiconductor is used to analyze dynamical
interaction induced weakening of localization in a system that is accessible to
experimental verification. The results show a dependence on the sign of the
two-particle interaction and on the optical excitation energy of the
Coulomb-correlated electron-hole pair.Comment: 4 pages and 3 ps figure
The luminosity function of Palomar 5 and its tidal tails
We present the main sequence luminosity function of the tidally disrupted
globular cluster Palomar 5 and its tidal tails. For this work we analyzed
imaging data obtained with the Wide Field Camera at the INT (La Palma) and data
from the Wide Field Imager at the MPG/ESO 2.2 m telescope at La Silla down to a
limiting magnitude of approximately 24.5 mag in B. Our results indicate that
preferentially fainter stars were removed from the cluster so that the LF of
the cluster's main body exhibits a significant degree of flattening compared to
other GCs. This is attributed to its advanced dynamical evolution. The LF of
the tails is, in turn, enhanced with faint, low-mass stars, which we interpret
as a consequence of mass segregation in the cluster.Comment: 4 pages, 3 figures, to be published in the proceedings of the
conference "Satellites and tidal streams" held at La Palma, Canary Islands,
May 26 - 30, 200
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