Helen J. Elwood

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We have determined the complete nucleotide sequence of the small-subunit ribosomal RNA genes for the ciliate protozoans Stylonychia pustulata and Oxytricha nova. The sequences are homologous and sufficiently similar that these organisms must be closely related. In a phylogeny inferred from comparisons of several eukaryotic small-subunit ribosomal RNAs, the(More)
An analysis of the small subunit ribosomal RNA (16S-like rRNA) from the protozoan Giardia lamblia provided a new perspective on the evolution of nucleated cells. Evolutionary distances estimated from sequence comparisons between the 16S-like rRNAs of Giardia lamblia and other eukaryotes exceed similar estimates of evolutionary diversity between(More)
Pneumocystis carinii pneumonia is the most common opportunistic infection in AIDS, and accounts for significant morbidity and mortality in these and other immunocompromised patients. P. carinii is a eukaryotic microorganism of uncertain taxonomy that can infect numerous mammalian hosts. Developing from a small, unicellular 'trophozoite' into a 'cyst'(More)
The phylogenetic relationships among the chlorophyte Chlamydomonas reinhardtii, the chrysophyte Ochromonas danica, and the oomycete Achyla bisexualis were explored by comparing the sequences of their small-subunit ribosomal RNA coding regions. Comparisons of similarity values or inspection of phylogenetic trees constructed by distance matrix methods reveal(More)
Seidel's combinatorial approach to the construction of real, symmetric matrices with unimodular entries and two eigenvalues has produced many equiangular Parseval frames for real Hilbert spaces. We follow Seidel's footsteps and develop a corresponding combinatorial characterization of complex Seidel matrices belonging to equiangular Parseval frames. We(More)
for taking the time to read my dissertation. Special thanks also to my friends and family for their ongoing support. ABSTRACT A frame is a family of vectors which provides stable expansions for vectors in Hilbert spaces. Equiangular Parseval frames are a special class of frames possessing optimality properties for many applications. Here we explore two(More)
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