48,927 research outputs found
Analysis of webs of partial-tension-field beams subjected to lateral pressure loadings
Webs of partial-tension-field beams subjected to lateral pressure loading
Foolproof quick-release locking pin
Locking pin can be withdrawn only when stress on the joint is negligible. Pin consists of a forward-pointing sleeve, a spring-loaded sliding handle, and a sliding plunger. Plunger movement controls installation and withdrawal of pin
A unified model for the long and high jump
A simple model based on the maximum energy that an athlete can produce in a
small time interval is used to describe the high and long jump. Conservation of
angular momentum is used to explain why an athlete should run horizontally to
perform a vertical jump. Our results agree with world records.Comment: Accepted for publication in Am. J. Phy
Economic growth and distribution of income: A growth model to fit Ghanaian data
Income distribution, economic growth, Development strategies,
Extension of geodesic algebras to continuous genus
Using the Penner--Fock parameterization for Teichmuller spaces of Riemann
surfaces with holes, we construct the string-like free-field representation of
the Poisson and quantum algebras of geodesic functions in the continuous-genus
limit. The mapping class group acts naturally in the obtained representation.Comment: 16 pages, submitted to Lett.Math.Phy
Localization transitions in non-Hermitian quantum mechanics
We study the localization transitions which arise in both one and two
dimensions when quantum mechanical particles described by a random
Schr\"odinger equation are subjected to a constant imaginary vector potential.
A path-integral formulation relates the transition to flux lines depinned from
columnar defects by a transverse magnetic field in superconductors. The theory
predicts that the transverse Meissner effect is accompanied by stretched
exponential relaxation of the field into the bulk and a diverging penetration
depth at the transition.Comment: 4 pages (latex) with 3 figures (epsf) embedded in the text using the
style file epsf.st
Extracting Spooky-activation-at-a-distance from Considerations of Entanglement
Following an early claim by Nelson & McEvoy \cite{Nelson:McEvoy:2007}
suggesting that word associations can display `spooky action at a distance
behaviour', a serious investigation of the potentially quantum nature of such
associations is currently underway. This paper presents a simple quantum model
of a word association system. It is shown that a quantum model of word
entanglement can recover aspects of both the Spreading Activation equation and
the Spooky-activation-at-a-distance equation, both of which are used to model
the activation level of words in human memory.Comment: 13 pages, 2 figures; To appear in Proceedings of the Third Quantum
Interaction Symposium, Lecture Notes in Artificial Intelligence, vol 5494,
Springer, 200
Symbiotic stars in X-rays III: Suzaku observations
We describe the X-ray emission as observed with Suzaku from five symbiotic
stars that we selected for deep Suzaku observations after their initial
detection with ROSAT, ASCA and Swift. We find that the X-ray spectra of all
five sources can be adequately fit with absorbed, optically thin thermal plasma
models, with either single- or multi-temperature plasmas. These models are
compatible with the X-ray emission originating in the boundary layer between an
accretion disk and a white dwarf. The high plasma temperatures of kT keV
for all five targets were greater than expected for colliding winds. Based on
these high temperatures, as well as previous measurements of UV variability and
UV luminosity, and the large amplitude of X-ray flickering in 4 Dra, we
conclude that all five sources are accretion-powered through predominantly
optically thick boundary layers. Our X-ray data allow us to observe a small,
optically thin portion of the emission from these boundary layers. Given the
time between previous observations and these observations, we find that the
intrinsic X-ray flux and the intervening absorbing column can vary by factors
of three or more on a time scale of years. However, the location of the
absorber and the relationship between changes in accretion rate and absorption
are still elusive.Comment: 14 pages, 3 figures and 3 tables. Accepted to published 04/15/2016.
arXiv admin note: substantial text overlap with arXiv:1505.0063
Vortex Pinning and Non-Hermitian Quantum Mechanics
A delocalization phenomenon is studied in a class of non-Hermitian random
quantum-mechanical problems. Delocalization arises in response to a
sufficiently large constant imaginary vector potential. The transition is
related to depinning of flux lines from extended defects in type-II
superconductors subject to a tilted external magnetic field. The physical
meaning of the complex eigenvalues and currents of the non-Hermitian system is
elucidated in terms of properties of tilted vortex lines. The singular behavior
of the penetration length describing stretched exponential screening of a
perpendicular magnetic field (transverse Meissner effect), the surface
transverse magnetization, and the trapping length are determined near the
flux-line depinning point.Comment: 2-column 27-pages RevTex file with 35 eps figure files embedded.
Minor errors amended. To be published in Phys. Rev.
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