172,509 research outputs found
Discretely Holomorphic Parafermions in Lattice Z(N) Models
We construct lattice parafermions - local products of order and disorder
operators - in nearest-neighbor Z(N) models on regular isotropic planar
lattices, and show that they are discretely holomorphic, that is they satisfy
discrete Cauchy-Riemann equations, precisely at the critical
Fateev-Zamolodchikov (FZ) integrable points. We generalize our analysis to
models with anisotropic interactions, showing that, as long as the lattice is
correctly embedded in the plane, such discretely holomorphic parafermions exist
for particular values of the couplings which we identify as the anisotropic FZ
points. These results extend to more general inhomogeneous lattice models as
long as the covering lattice admits a rhombic embedding in the plane.Comment: v2: minor corrections; v3: published version - minor corrections and
reference adde
A moving mesh method for one-dimensional hyperbolic conservation laws
We develop an adaptive method for solving one-dimensional systems of hyperbolic conservation laws that employs a high resolution Godunov-type scheme for the physical equations, in conjunction with a moving mesh PDE governing the motion of the spatial grid points. Many other moving mesh methods developed to solve hyperbolic problems use a fully implicit discretization for the coupled solution-mesh equations, and so suffer from a significant degree of numerical stiffness. We employ a semi-implicit approach that couples the moving mesh equation to an efficient, explicit solver for the physical PDE, with the resulting scheme behaving in practice as a two-step predictor-corrector method. In comparison with computations on a fixed, uniform mesh, our method exhibits more accurate resolution of discontinuities for a similar level of computational work
USGS/NOAA Workshop on Mycobacteriosis in Striped Bass, May 7-10, 2006, Annapolis, Maryland
As a Federal trust species, the well-being of the striped bass (Morone saxatilis) population along the Eastern Seaboard is of major concern to resource users. Striped bass are an extremely valuable commercial and recreational resource. As a principal piscivore in Chesapeake Bay, striped bass directly or indirectly interact with multiple trophic levels within the ecosystem and are therefore very sensitive to biotic and abiotic ecosystem changes. For reasons that have yet to be defined, the species has a high intrinsic susceptibility to mycobacteriosis. This disease has been impacting Chesapeake Bay striped bass since at least the 1980s as indicated by archived tissue samples. However, it was not until heightened incidences of fish with skin lesions in the Pocomoke River and other tributaries of the Chesapeake Bay were reported in the summer and fall of 1996 and 1997 that a great deal of public and scientific interest was stimulated about concerns for fish disease in the Bay. (PDF contains 50 pages
A Survey of Sport Fishing in the Illinois Portion of Lake Michigan March through September 1997
F-52-R12Report issued on: May 1998INHS Technical Report prepared for Illinois Department of Natural Resource
- …