Open Access. Powered by Scholars. Published by Universities.®

Physical Sciences and Mathematics Commons

Open Access. Powered by Scholars. Published by Universities.®

Articles 1 - 7 of 7

Full-Text Articles in Physical Sciences and Mathematics

Riesz Bases Of Root Vectors Of Indefinite Sturm-Liouville Problems With Eigenparameter Dependent Boundary Conditions. Ii, Paul Binding, Branko Ćurgus Apr 2009

Riesz Bases Of Root Vectors Of Indefinite Sturm-Liouville Problems With Eigenparameter Dependent Boundary Conditions. Ii, Paul Binding, Branko Ćurgus

Mathematics Faculty Publications

We consider a regular indefinite Sturm-Liouville problem with two self-adjoint boundary conditions affinely dependent on the eigenparameter. We give sufficient conditions under which the root vectors of this Sturm-Liouville problem can be selected to form a Riesz basis of a corresponding weighted Hilbert space.


Highly Connected Random Geometric Graphs, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters Jan 2009

Highly Connected Random Geometric Graphs, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters

Mathematics Faculty Publications

Let P be a Poisson process of intensity 1 in a square Sn of area n. We construct a random geometric graph Gn,k by joining each point of P to its k nearest neighbours. For many applications it is desirable that Gn,k is highly connected, that is, it remains connected even after the removal of a small number of its vertices. In this paper we relate the study of the s-connectivity of Gn,k to our previous work on the connectivity of Gn,k. Roughly speaking, we show that for s=o(logn), the threshold (in k) for …


Optical Tomography For Media With Variable Index Of Refraction, Stephen R. Mcdowall Jan 2009

Optical Tomography For Media With Variable Index Of Refraction, Stephen R. Mcdowall

Mathematics Faculty Publications

Optical tomography is the use of near-infrared light to determine the optical absorption and scattering properties of a medium M ⊂ Rn. If the refractive index is constant throughout the medium, the steady-state case is modeled by the stationary linear transport equation in terms of the Euclidean metric and photons which do not get absorbed or scatter travel along straight lines. In this expository article we consider the case of variable refractive index where the dynamics are modeled by writing the transport equation in terms of a Riemannian metric; in the absence of interaction, photons follow the geodesics …


Modulation Invariant Bilinear T(1) Theorem, Árpád Bényi, Ciprian Demeter, Andrea R. Nahmod, Christoph M. Thiele, Rodolfo H. (Rudolfo Humberto) Torres, Paco Villarroya Jan 2009

Modulation Invariant Bilinear T(1) Theorem, Árpád Bényi, Ciprian Demeter, Andrea R. Nahmod, Christoph M. Thiele, Rodolfo H. (Rudolfo Humberto) Torres, Paco Villarroya

Mathematics Faculty Publications

We prove a T(1) theorem for bilinear singular integral operators (trilinear forms) with a one-dimensional modulation symmetry.


Local Well-Posedness Of Nonlinear Dispersive Equations On Modulation Spaces, Árpád Bényi, Kasso A. Okoudjou Jan 2009

Local Well-Posedness Of Nonlinear Dispersive Equations On Modulation Spaces, Árpád Bényi, Kasso A. Okoudjou

Mathematics Faculty Publications

By using tools of time-frequency analysis, we obtain some improved local well-posedness results for the nonlinear Schrödinger, nonlinear wave and nonlinear Klein–Gordon equations with Cauchy data in modulation spaces ℳ0,sp,1.


A Critical Constant For The K Nearest-Neighbour Model, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters Jan 2009

A Critical Constant For The K Nearest-Neighbour Model, Paul Balister, Béla Bollobás, Amites Sarkar, Mark Walters

Mathematics Faculty Publications

Let P be a Poisson process of intensity 1 in a square Sn of area n. For a fixed integer k, join every point of P to its k nearest neighbours, creating an undirected random geometric graph Gn,k. We prove that there exists a critical constant ccrit such that, for cccrit, Gn,⌊clogn⌋ is disconnected with probability tending to 1 as n →∞ and, for cccrit, Gn,⌊clogn⌋ is connected with probability tending to 1 as n →∞. This answers a question …


Numerical Bifurcation Of Separable Parameterized Equations, Yun-Qiu Shen, Tjalling Ypma Jan 2009

Numerical Bifurcation Of Separable Parameterized Equations, Yun-Qiu Shen, Tjalling Ypma

Mathematics Faculty Publications

Many applications give rise to separable parameterized equations, which have the form A(y, µ)z + b(y, µ) = 0, where zRN , yRn, µRs, and the (N + n) × N matrix A(y, µ) and (N + n) vector b(y, µ) are C2 -Lipschitzian in (y, µ) ∈ Ω ⊂ Rn × Rs. We present a technique which reduces the original equation to the form …