A study of choral music styles including current listings of available octavo music, collections and recordings from the Renaissance Period through the Early Romantic Period (1450-1800) for the high school or college choral director

Thesis (M.M.E.)--Boston Universit

Effects of transmission line compensation and power factor correction on harmonic propagation

This thesis addresses power quality at two different levels, transmission and utilization. Harmonics injected at these levels can severely degrade the performance and long term reliability of the power system; At the utilization level, a typical industrial power system configuration that requires power factor capacitors and tuned harmonic filters for reactive power compensation and harmonic-control is analyzed. The resonant conditions for a given power factor correction or harmonic frequency are determined directly from the roots of a quadratic expression. This formulation allows a quick evaluation of the power factor range with excessive harmonic levels and reveals the effect of tuned reactors on the resonant frequencies; At the transmission level, a method for analyzing series capacitor placement on long transmission lines to improve line loadability is described. The influence of the compensator on harmonic current propagation and circuit resonant frequencies is investigated. Computer simulations are performed on an actual 345 kV, 238 mile line

Assembly, remodelled

Biochemical assays reveal that nucleosome maturation and chromatin remodelling by the motor protein Chd1 are distinct, separable enzymatic activities

Life on the edge : the role of habitat selection on vole density near forest boundaries

Theories of density-dependent habitat selection predict pronounced gradients of population density near habitat edges. Population density in high-quality habitats should decline toward edges with lower-quality habitats, and population density in low-quality habitats should increase toward boundaries with higher-quality habitats. This pattern should be more obvious near abrupt boundaries than near ecotones where habitats gradually grade one into the other. 1 tested the predictions using the density of red-backed voles (Clethrionomys gapperi) along eight belt transects crossing edges between natural and anthropogenic boreal forest habitats in northwestern Ontario. Transects were classified as having either a gradual (70 m to 90 m ecotone) or abrupt edge (20m ecotone). Vole density varied consistently between pairs of habitats, but there was no detectable gradient in density at either abrupt or gradual edges. The absence of an edge effect may be related to errors in the assessment of habitat quality by individuals confronted with a matrix of patch types near edges separating similar habitats. Another possibility is that an, as yet, unidentified agent or process alters the quality of red-backed vole habitats near boreal-forest edges

The structure of glucose-fructose oxidoreductase from Zymomonas mobilis: an osmoprotective periplasmic enzyme containing non-dissociable NADP

AbstractBackground The organism Zymomonas mobilis occurs naturally in sugar-rich environments. To protect the bacterium against osmotic shock, the periplasmic enzyme glucose-fructose oxidoreductase (GFOR) produces the compatible, solute sorbitol by reduction of fructose, coupled with the oxidation of glucose to gluconolactone. Hence, Z. mobilis can tolerate high concentrations of sugars and this property may be useful in the development of an efficient microbial process for ethanol production. Each enzyme subunit contains tightly associated NADP which is not released during the catalytic cycle.Results The structure of GFOR was determined by X-ray crystallography at 2.7 å resolution. Each subunit of the tetrameric enzyme comprises two domains, a classical dinucleotide-binding domain, and a C-terminal domain based on a predominantly antiparallel nine-stranded β sheet. In the tetramer, the subunits associate to form two extended 18-stranded β sheets, which pack against each other in a face to face fashion, creating an extensive interface at the core of the tetramer. An N-terminal arm from each subunit wraps around the dinucleotide-binding domain of an adjacent subunit, covering the adenine ring of NADP.Conclusions In GFOR, the NADP is found associated with a classical dinucleotide-binding domain in a conventional fashion. The NADP is effectively buried in the protein-subunit interior as a result of interactions with the N-terminal arm from an adjacent subunit in the tetramer, and with a short helix from the C-terminal domain of the protein. This accounts for NADP's inability to dissociate. The N-terminal arm may also contribute to stabilization of the tetramer. The enzyme has an unexpected structural similarity with the cytoplasmic enzyme glucose-6-phosphate dehydrogenase (G6PD). We hypothesize that both enzymes have diverged from a common ancestor. The mechanism of catalysis is still unclear, but we have identified a conserved structural motif (Glu–Lys–Pro) in the active site of GFOR and G6PD that may be important for catalysis