3,040 research outputs found
Lattice Green Function (at 0) for the 4d Hypercubic Lattice
The generating function for recurrent Polya walks on the four dimensional
hypercubic lattice is expressed as a Kampe-de-Feriet function. Various
properties of the associated walks are enumerated.Comment: latex, 5 pages, Res. Report 1
Analysis of the second order exchange self energy of a dense electron gas
We investigate the evaluation of the six-fold integral representation for the
second order exchange contribution to the self energy of a three dimensional
electron gas at the Fermi surface.Comment: 6 page
A gauge-compatible Hamiltonian splitting algorithm for particle-in-cell simulations using finite element exterior calculus
A particle-in-cell algorithm is derived with a canonical Poisson structure in
the formalism of finite element exterior calculus. The resulting method belongs
to the class of gauge-compatible splitting algorithms, which exactly preserve
gauge symmetries and their associated conservation laws via the momentum map.
We numerically demonstrate this time invariance of the momentum map and its
usefulness in establishing precise initial conditions with a desired initial
electric field and fixed background charge. The restriction of this canonical,
finite element Poisson structure to the 1X2P phase space is also considered and
simulated numerically
Logarithmic interaction under periodic boundary conditions: Closed form formulas for energy and forces
A method is given to obtain closed form formulas for the energy and forces
for an aggregate of charges interacting via a logarithmic interaction under
periodic boundary conditions. The work done here is a generalization of
Glasser's results [M. L. Glasser, J. Math. Phys. 15, 188 (1974)] and is
obtained with a different and simpler method than that by Stremler [M. A.
Stremler, J. Math. Phys. 45, 3584 (2004)]. The simplicity of the formulas
derived here makes them extremely convenient in a computer simulation
Dynamics of accommodative fatigue in rhesus monkeys and humans
AbstractChanges in accommodative dynamics with repeated accommodation were studied in three anesthetized rhesus monkeys and two conscious humans. Maximum accommodation was centrally stimulated via the Edinger–Westphal nucleus in monkeys with a 4 s on, 4 s off paradigm (4×4) for 17 min, 4×1.5 for 27 min and 2×1 for 16 min. Humans accommodated repeatedly to visual targets (5×5; 5D and 2×2; 6D) for 30 min. In all cases, accommodation was sustained throughout. The anesthetized monkeys showed inter-individual variability in the extent of changes in accommodative dynamics over time while no systematic changes were detected in the human accommodative responses. Little accommodative fatigue was found compared to previous studies which have reported a complete loss of accommodation after 5 min of repeated stimulation in monkeys
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