Recent Submissions

  • Spatiotemporal Distributions of Migratory Birds: Patchy Models with Delay 

    Author(s):Gourley, S. A.; Liu, Rongsong; Wu, J. H.; Gourley, S. A.; Liu, Rongsong; Wu, J. H.
    Date:2010-01-01
    We derive and analyze a mathematical model for the spatiotemporal distribution of a migratory bird species. The birds have specific sites for breeding and winter feeding, and usually several stopover sites along the migration ...
  • Interaction of Migratory Birds and Domestic Poultry and Its Role in Sustaining Avian Influenza, The 

    Author(s):Bourouiba, L.; Gourley, S. A.; Liu, Rongsong; Wu, J. H.; Bourouiba, L.; Gourley, S. A.; Liu, Rongsong; Wu, J. H.
    Date:2011-01-01
    We investigate the role of migratory birds in the spread of H5N1 avian influenza, focusing on the interaction of a migratory bird species with nonmigratory poultry. The model is of patch type and is derived with the aid ...
  • Simple Proof of Fiedler's Conjecture Concerning Orthogonal Matrices, A 

    Author(s):Shader, Bryan L.; Shader, Bryan L.
    Date:1997-09-01
    We give a simple proof that an n x n orthogonal matrix with n ≥ 2 which cannot be written as a direct sum has at least 4n-4 nonzero entries.
  • Distances in Weighted Trees and Group Inverse of Laplacian Matrices 

    Author(s):Kirkland, S. J.; Neumann, M.; Shader, Bryan L.; Kirkland, S. J.; Neumann, M.; Shader, Bryan L.
    Date:1997-10-01
    In this paper we find formulas for group inverses of Laplacians of weighted trees. We then develop a relationship between entries of the group inverse and various distance functions on trees. In particular, we show that ...
  • On Matrices with Signed Null Spaces 

    Author(s):Kim, S. J.; Shader, Bryan L.; Hwang, S. G.; Kim, S. J.; Shader, Bryan L.; Hwang, S. G.
    Date:2002-12-19
    We denote by Q(A) the set of all matrices with the same sign pattern as A. A matrix A has signed null-space provided there exists a set S of sign patterns such that the set of sign patterns of vectors in the null-space of ...
  • Sign Patterns That Allow a Positive or Nonnegative Left Inverse 

    Author(s):Kim, I. J.; Olesky, D. D.; Shader, Bryan L.; Van den Driessche, P.; Kim, I. J.; Olesky, D. D.; Shader, Bryan L.; Van den Driessche, P.
    Date:2006-01-01
    An m by n sign pattern S is an m by n matrix with entries in {+,-, 0}. Such a sign pattern allows a positive (resp., nonnegative) left inverse, provided that there exist an m by n matrix A with the sign pattern S and an n ...
  • Reconstruction of a Spherically Symmetrical Speed of Sound 

    Author(s):McLaughlin, J. R.; Polyakov, Peter; Sacks, P. E.; McLaughlin, J. R.; Polyakov, Peter; Sacks, P. E.
    Date:1994-10-01
    Consider the inverse acoustic scattering problem for a spherically symmetric inhomogeneity of compact support that arises, among other places, in nondestructive testing. Define the corresponding homogeneous and inhomogeneous ...
  • Domain Decomposition Operator Splittings for the Solution of Parabolic Equations 

    Author(s):Mathew, T. P.; Polyakov, Peter; Russo, G.; Wang, J.; Mathew, T. P.; Polyakov, Peter; Russo, G.; Wang, J.
    Date:1998-05-01
    We study domain decomposition counterparts of the classical alternating direction implicit (ADI) and fractional step (FS) methods for solving the large linear systems arising from the implicit time stepping of parabolic ...
  • Particle Method and Numerical Study of a Quasilinear Partial Differential Equation, A 

    Author(s):Camassa, R.; Chiu, P. H.; Lee, Long; Sheu, T. W. H.; Camassa, R.; Chiu, P. H.; Lee, Long; Sheu, T. W. H.
    Date:2011-09-01
    We present a particle method for studying a quasilinear partial differential equation (PDE) in a class proposed for the regularization of the Hopf (inviscid Burger) equation via nonlinear dispersion-like terms. These are ...
  • Automatic Differentiability and Characterization of Cocycles of Holomorphic Flows 

    Author(s):Jafari, Farhad; Tonev, T.; Toneva, E.; Jafari, Farhad; Tonev, T.; Toneva, E.
    Date:2005-01-01
    In this paper we prove that cocycles of holomorphic flows on domains in the complex plane are automatically differentiable with respect to the flow parameter, and their derivatives are holomorphic functions. We use this ...
  • Set of All MXN Rectangular Real Matrices of Rank-R Is Connected by Analytic Regular Arcs, The 

    Author(s):Evard, J. C.; Jafari, Farhad; Evard, J. C.; Jafari, Farhad
    Date:1994-02-01
    It is well known that the set of all square invertible real matrices has two connected components. The set of all m x n rectangular real matrices of rank r has only one connected component when m ≠ n or r < m = n. We show ...
  • Novel Method for Solving Multiscale Elliptic Problems with Randomly Perturbed Data, A 

    Author(s):Ginting, Victor; Malqvist, A.; Presho, M.; Ginting, Victor; Malqvist, A.; Presho, M.
    Date:2010-01-01
    We propose a method for efficient solution of elliptic problems with multiscale features and randomly perturbed coefficients. We use the multiscale finite element method (MsFEM) as a starting point and derive an algorithm ...
  • Renormalization Group Analysis of Nonlinear Diffusion Equations with Time Dependent Coefficients: Analytical Results 

    Author(s):Braga, G. A.; Furtado, Fred; Moreira, J. M.; Rolla, L. T.; Braga, G. A.; Furtado, Fred; Moreira, J. M.; Rolla, L. T.
    Date:2007-06-01
    We study the long-time asymptotics of a certain class of nonlinear diffusion equations with time-dependent diffusion coefficients which arise, for instance, in the study of transport by randomly fluctuating velocity fields. ...
  • Renormalization Group Analysis of Nonlinear Diffusion Equations with Periodic Coefficients 

    Author(s):Braga, G. A.; Furtado, Fred; Moreira, J. M.; Rolla, L. T.; Braga, G. A.; Furtado, Fred; Moreira, J. M.; Rolla, L. T.
    Date:2003-01-01
    In this paper we present an efficient numerical approach based on the renormalization group method for the computation of self-similar dynamics. The latter arise, for instance, as the long-time asymptotic behavior of ...
  • Scaling Analysis for the Tracer Flow Problem in Self-Similar Permeability Fields 

    Author(s):Borges, M. R.; Furtado, Fred; Pereira, Felipe; Souto, H. P. A.; Borges, M. R.; Furtado, Fred; Pereira, Felipe; Souto, H. P. A.
    Date:2008-01-01
    The spatial variations in porous media (aquifers and petroleum reservoirs) occur at all length scales (from the pore to the reservoir scale) and are incorporated into the governing equations for multiphase flow problems ...
  • Large Deviation Principle and Inviscid Shell Models 

    Author(s):Bessaih, Hakima; Millet, A.; Bessaih, Hakima; Millet, A.
    Date:2009-11-26
    A LDP is proved for the inviscid shell model of turbulence. As the viscosity coefficient v converges to 0 and the noise intensity is multiplied by root v, we prove that some shell models of turbulence with a multiplicative ...
  • Evolution of a Random Vortex Filament, The 

    Author(s):Bessaih, Hakima; Gubinelli, M.; Russo, F.; Bessaih, Hakima; Gubinelli, M.; Russo, F.
    Date:2005-09-01
    We study an evolution problem in the space of continuous loops in a three-dimensional Euclidean space modeled upon the dynamics of vortex lines in 3d incompressible and inviscid fluids. We establish existence of a local ...
  • Influence of Phosphate Source on Vesicular-Arbuscular Mycorrhizae of Bouteloua-Gracilis 

    Author(s):Allen, Michael F.; Sexton, J. C.; Moore, J. C.; Christensen, M.; Allen, Michael F.; Sexton, J. C.; Moore, J. C.; Christensen, M.
    Date:1981-01-01
    Non-mycorrhizal and vesicular-arbuscular mycorrhizal Bouteloua gracilis infected with Glomus fasciculatus were grown in defined media containing different phosphate sources and compared with respect to phosphate content ...
  • Comparative Water Relations and Photosynthesis of Mycorrhizal and Non-Mycorrhizal Bouteloua-Gracilis HBK Lag Ex Steud 

    Author(s):Allen, Michael F.; Smith, W. K.; Moore, T. S.; Christensen, M.; Allen, Michael F.; Smith, W. K.; Moore, T. S.; Christensen, M.
    Date:1981-01-01
    The rangeland grass, Bouteloua gracilis was inoculated with its mycorrhizal symbiont, Glomus fasciculatus, to determine the influence of vesicular-arbuscular mycorrhizae on water status, stomatal behaviour and photosynthesis ...