Barbara A. Lee

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Mechanistic analysis of transcriptional initiation and termination by RNA polymerase II (PolII) indicates that some factors are common to both processes. Here we show that two long genes of Saccharomyces cerevisiae, FMP27 and SEN1, exist in a looped conformation, effectively bringing together their promoter and terminator regions. We also show that PolII is(More)
We study a model system of two strictly hyperbolic conservation laws which is genuinely nonlinear but for which the Riemann problem has no global solution. Singular solutions are deened by means of a generalized Rankine-Hugoniot relation and an overcompressive condition on the discontinuity. We show that approximate solutions which can be constructed by(More)
A large, multi-province outbreak of listeriosis associated with ready-to-eat meat products contaminated with Listeria monocytogenes serotype 1/2a occurred in Canada in 2008. Subtyping of outbreak-associated isolates using pulsed-field gel electrophoresis (PFGE) revealed two similar but distinct Asc I PFGE patterns. High-throughput pyrosequencing of two L.(More)
Reconstruction of a gene with its introns removed results in reduced levels of cytoplasmic mRNA. This is partly explained by introns promoting the export of mRNA through coupling splicing to nuclear export processes. However, we show here that splicing signals can have a direct role in enhancing gene transcription. Removal of promoter proximal splice(More)
A plant can respond to the threat of a pathogen through resistance defenses or through tolerance. Resistance has been widely studied in many host pathogen systems but little is known about genetic changes which underlie a tolerant interaction. A recently developed model system for a tolerant tomato (Lycopersicon esculentum Mill) interaction with a fungal(More)
We solve the Dirichlet problem for a nonlinear degenerate elliptic equation that arises in modeling weak shock reeection at a wedge. The equation exhibits a nonlinear version of a degeneracy rst studied by Keldysh. Using monotone operator techniques, we prove existence of a weak solution in a weighted Sobolev space. For negative boundary data, the solution(More)
One way of modeling the evolution in time of an age-structured population is to set up the evolution process as a partial diierential equation in which time and age are the independent variables. The resulting equation, known as the McKendrick equation, has received attention recently from mathematicians. Some advantages of the PDE are that it can easily be(More)
In this paper we validate the Generalized Geometric Entropy Criterion for admissibility of shocks in systems which change type. This condition states that a shock between a state in a hyperbolic region and one in a nonhyperbolic region is admissible if the Lax Geometric Entropy Criterion, based on the number of characteristics entering the shock, holds,(More)