345,608 research outputs found
Transport coefficients and cross sections for electrons in water vapour: comparison of cross section sets using an improved Boltzmann equation solution
This paper revisits the issues surrounding computation of electron transport properties in water vapour as a function of E/n0 (the ratio of the applied electric field to the water vapour number density) up to 1200 Td. We solve the Boltzmann equation using an improved version of the code of Ness and Robson [Phys. Rev. A 38, 1446 (1988)], facilitating the calculation of transport coefficients to a considerably higher degree of accuracy. This allows a correspondingly more discriminating test of the various electron–water vapour cross section sets proposed by a number of authors, which has become an important issue as such sets are now being applied to study electron driven processes in atmospheric phenomena [P. Thorn, L. Campbell, and M. Brunger, PMC Physics B 2, 1 (2009)] and in modeling charged particle tracks in matter [A. Munoz, F. Blanco, G. Garcia, P. A. Thorn, M. J. Brunger, J. P. Sullivan, and S. J. Buckman, Int. J. Mass Spectrom. 277, 175 (2008)]
Boston University Wind Ensemble: David J. Martins, conductor, October 19, 1999
This is the concert program of the Boston University Wind Ensemble performance on Tuesday, October 19, 1999 at 8:00 p.m., at the Tsai Performance Center, 685 Commonwealth Avenue. Works performed were Two Marches for the Sultan Abdul Medjid (arr. Townsend) by Gaetano Donizetti, Serenade No. 12 in C minor, K. 388 by Wolfgang Amadeus Mozart, Gavorkna Fanfare by Jack Stamp, A Movement for Rosa by Mark Camphouse, "Loch Ness:" A Scottish Fantasy by Johan de Meij. Digitization for Boston University Concert Programs was supported by the Boston University Humanities Library Endowed Fund
Non-equilibrium steady state of sparse systems
A resistor-network picture of transitions is appropriate for the study of
energy absorption by weakly chaotic or weakly interacting driven systems. Such
"sparse" systems reach a novel non-equilibrium steady state (NESS) once coupled
to a bath. In the stochastic case there is an analogy to the physics of
percolating glassy systems, and an extension of the fluctuation-dissipation
phenomenology is proposed. In the mesoscopic case the quantum NESS might differ
enormously from the stochastic NESS, with saturation temperature determined by
the sparsity. A toy model where the sparsity of the system is modeled using a
log-normal random ensemble is analyzed.Comment: 6 pages, 6 figures, EPL accepted versio
Two Faculty Members Appointed as Distinguished Professors
Kenneth J. Sufka and Robert Van Ness honored for their teaching, research and servic
Independent electrons model for open quantum systems: Landauer-Buettiker formula and strict positivity of the entropy production
A general argument leading from the formula for currents through an open
noninteracting mesoscopic system given by the theory of non-equilibrium steady
states (NESS) to the Landauer-Buettiker formula is pointed out. Time reversal
symmetry is not assumed. As a consequence it follows that, as far as the system
has a nontrivial scattering theory and the reservoirs have different
temperatures and/or chemical potentials, the entropy production is strictly
positive.Comment: 12 pages. Submitted for publication in J. Math. Phys. on 2006-06-05.
Revision and extension of: G. Nenciu, A general proof of Landauer-Buettiker
formula, [math-ph/0603030
Stripe fractionalization II: the quantum spin nematic and the Abrikosov lattice
In part (I) of this two paper series on stripe fractionalization, we argued
that in principle the `domain wall-ness' of the stripe phase could persist in
the spin and charge disordered superconductors, and we demonstrated how this
physics is in one-to-one correspondence with Ising gauge theory. Here we focus
on yet another type of order suggested by the gauge theory: the quantum spin
nematic. Although it is not easy to measure this order directly, we argue that
the superconducting vortices act as perturbations destroying the gauge symmetry
locally. This turns out to give rise to a simple example of a gauge-theoretical
phenomenon known as topological interaction. As a consequence, at any finite
vortex density a globally ordered antiferromagnet emerges. This offers a
potential explanation for recent observations in the underdoped 214 system
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