In 1903 Karl Pearson identified the effects of censorship, or range restriction, on the correlation coefficient. The current report reviews the history and literature examining those effects, corrections for range restriction, and the limitations of previous research. A rationale for further research of the effect of range restriction on logistic regression parameter estimates is presented. / text

American composer David Guion (1892-1981) created and expressed in much of his music a unique and unmistakably American voice. Though he is remembered today mostly for piano pieces, especially Turkey in the Straw and Arkansas Traveler, he was famous for championing cowboy songs, African-American spirituals and folk songs as the truly authentic representations of the American experience. He also wrote many original works, including a substantial number of songs in Black dialect. In 1930 Guion starred in a cowboy show at the Roxy Theatre in New York, drawing upon his western-themed music. The next year he had a weekly radio show, broadcast around the country and featuring his music exclusively, with the title Hearing America with Guion. He played a substantial role in transforming Home on the Range into the best-known of all cowboy songs. His magnum opus, the ballet Shingandi, was highly regarded but has yet to be recorded. This dissertation examines those genres among Guion’s compositions that reveal his vision for a musical Americana. Much of his music is based on songs that circulated first in oral tradition before he adapted them for the concert stage. This dissertation surveys the breadth of the oral tradition of these songs, identifies his direct sources, and examines his treatment of melody, rhythm and harmony as he infused his music with such characteristic national flavor that his audiences were, in effect, “Hearing America.” A complete list of Guion compositions is attempted, and to the extent possible, probable dates of composition are established from recital programs and publication agreements. The scripts of his radio shows are reconstructed from papers in his archives and presented here. / text

Synthetic aperture radar (SAR) is an imaging technique based on the radio reflectivity of the target being imaged. SAR instruments offer many advantages over optical imaging due to the ability to form coherent images in inclement weather, at night, and through ground cover. High resolution is achieved in azimuth through a synthesized aperture much larger than the physical antenna of the imaging device. Consequently, proper focusing requires accurate information about the relative motion between the antenna phase center and the scene. Any unknown target velocity, acceleration, rotation, or vibration will introduce errors in the image. This work addresses a novel method of focusing a moving target in a SAR image through the estimation of various motion parameters. The target azimuth position is determined through monopulse radar, at which point range velocity and acceleration are estimated across a series of overlapping sub-apertures. Cross-range velocity is then estimated through a search to optimize an image quality metric such as entropy or contrast. A final focused image is then generated based on this velocity vector. Methods of extending this work for a single phase center system are considered. This technique is demonstrated with real radar data from an experimental system, and the performance of this technique is compared both subjectively and with a variety of image metrics to the MITRE keystone technique. Finally, extensions to this current line of research are considered. / text

Pedicle screw-rod instrumentation is considered a standard treatment for spinal instability, and titanium is the most common material for this application. Cobalt-chromium has several advantages over titanium and is generating interest in orthopedic practice. The aim of this study was to compare titanium versus cobalt-chromium rods in posterior fusion, with and without transverse connectors, through in vitro biomechanical testing and determine the optimal configuration. Six cadaveric lumbar spines (L1-S1) were used. Posterior and middle column injuries were simulated at L3-L5 and different pedicle screw constructs were implanted. Specimens were subjected to flexibility tests and range of motion, intradiscal pressure and axial rotation energy loss were statistically compared among the following conditions: intact, titanium rods (without transverse connectors), titanium rods with transverse connectors, cobalt-chromium rods (without transverse connectors) and cobalt-chromium rods with transverse connectors. The novel measurement of energy loss was examined to determine its viability in fusion investigations. All fusion constructs significantly (p0.05) were observed in axial rotation among all conditions. Intradiscal pressure significantly increased (p≤0.01) after fusion, except for the cobalt-chrome conditions in extension (p≥0.06), and no significant differences (p>0.99) were found among fixation constructs. Energy loss, differences became significant between the cobalt-chrome with transverse connector condition with respect to the cobalt-chrome (p=0.05) and titanium (p There is not enough evidence to support that the cobalt-chrome rods performed biomechanically different than the titanium rods. The use of titanium rods may be more beneficial because there is a lower probability of corrosion. The inclusion of the transverse connector only increased stability for the cobalt-chromium construct in axial rotation, which suggests that it is beneficial in complete facetectomy procedures.

Alluvial groundwater systems are an important source of water for communities and biodiverse riparian corridors throughout the arid and semi-arid Basin and Range Geological Province of western North America. These aquifers and their attendant desert streams have been depleted to support a growing population, while projected climate change could lead to more extreme episodes of drought and precipitation in the future. The only source of replenishment to these aquifers is recharge. This dissertation builds upon previous work to characterize and quantify recharge in arid and semi-arid basins by characterizing the intra-annual seasonality of recharge across the Basin and Range Province, and considering how climate change might impact recharge seasonality and volume, as well as fragile riparian corridors that depend on these hydrologic processes. First, the seasonality of recharge in a basin in the sparsely-studied southern extent of the Basin and Range Province is determined using stable water isotopes of seasonal precipitation and groundwater, and geochemical signatures of groundwater and surface water. In northwestern Mexico in the southern reaches of the Basin and Range, recharge is dominated by winter precipitation (69% ± 42%) and occurs primarily in the uplands. Second, isotopically-based estimates of seasonal recharge fractions in basins across the region are compared to identify patterns in recharge seasonality, and used to evaluate a simple water budget-based model for estimating recharge seasonality, the normalized seasonal wetness index (NSWI). Winter precipitation makes up the majority of annual recharge throughout the region, and North American Monsoon (NAM) precipitation has a disproportionately weak impact on recharge. The NSWI does well in estimating recharge seasonality for basins in the northern Basin and Range, but less so in basins that experience NAM precipitation. Third, the seasonal variation in riparian and non-riparian vegetation greenness, represented by the normalized difference vegetation index (NDVI), is characterized in several of the study basins and climatic and hydrologic controls are identified. Temperature was the most significant driver of vegetation greenness, but precipitation and recharge seasonality played a significant role in some basins at some elevations. Major contributions of this work include a better understanding of recharge in a monsoon-dominated basin, the characterization of recharge seasonality at a regional scale, evaluation of an estimation method for recharge seasonality, and an interpretation of the interaction of seasonal hydrologic processes, vegetation dynamics, and climate change.

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The effects of land-use history in the Animas Mountains, New Mexico (AM) and the Sierra los Ajos, Sonora (SLA) were studied in relation to morphological and soil chemical characteristics, radial and basal area growth, and forest structure. Litter depth, organic matter, total nitrogen, CEC, and exchangeable cations were greater in the AM than in the SLA, apparently as a result of differences in fire frequency and other land uses. Seasonal precipitation (October-January) was reconstructed for the AM. Annual precipitation (July-July) was reconstructed for the SLA. July PDSI was reconstructed for both mountain ranges. Fires in the AM were preceded by relatively wet conditions two years before the fire year. No significant climate-fire relationship was found in the SLA. Tree radial and basal area increase differed between mountain ranges, suggesting that annual growth was influenced by differences in land-use history. Fire suppression activities and other land uses in the AM apparently have produced an increase in tree density and dominance of shade-tolerant but less-fire resistant species (i.e. Douglas-fir, southwestern white pine, pinyon pine). More frequent fires and logging activities in the SLA apparently have produced lower tree densities and dominance by shade-intolerant ponderosa pine.