Richard J. Wallace

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The recent explosion of newly described species of Nocardia results from the impact in the last decade of newer molecular technology, including PCR restriction enzyme analysis and 16S rRNA sequencing. These molecular techniques have revolutionized the identification of the nocardiae by providing rapid and accurate identification of recognized nocardiae and,(More)
The history, taxonomy, geographic distribution, clinical disease, and therapy of the pathogenic nonpigmented or late-pigmenting rapidly growing mycobacteria (RGM) are reviewed. Community-acquired disease and health care-associated disease are highlighted for each species. The latter grouping includes health care-associated outbreaks and pseudo-outbreaks as(More)
Nontuberculous mycobacteria (NTM) are potential respiratory pathogens in cystic fibrosis (CF). To assess the species-specific prevalence and risk factors for acquisition, we conducted a prospective, cross-sectional study of the prevalence of NTM and clinical features of patients at 21 U.S. centers. Almost 10% of patients with CF who were 10 years or older(More)
The constraint satisfaction problem (CSP) is a potential area of application for anytime methods. In this work we derive anytime curves using a partial constraint satisfaction framework that encompasses problems with complete solutions and those that allow only partial solutions of varying quality. In either case, the curves should converge on optimal(More)
On the basis of its optimal asymptotic time complexity, AC-4 is often considered the best algorithm for establishing arc consistency in constraint satisfaction problems (CSPs). In the present work, AC3 was found to be much more efficient than AC-4, for CSPs with a variety of features. (Variable pairs were in lexical order, and in AC-3 they were added to the(More)
An important extension of constraint technology involves problems that undergo changes that may invalidate the current solution. Previous work on dynamic problems sought methods for eeciently nding new solutions. We take a more proactive approach, exploring methods for nding solutions more likely to remain valid after changes that temporarily alter the set(More)
Mycobacterium abscessus infections tend to respond poorly to macrolide-based chemotherapy, even though the organisms appear to be susceptible to clarithromycin. Circumstantial evidence suggested that at least some M. abscessus isolates might be inducibly resistant to macrolides. Thus, the purpose of this study was to investigate the macrolide phenotype of(More)