No Abstract provided / Thesis / Bachelor of Arts (BA)

It was hypothesized that effect size in therapy outcome research would correlate positively with congruence effects. Congruence was defined as the degree to which what had been practiced in treatment was scored as improvement when outcome was measured. Additionally, it was hypothesized that correcting effect sizes for estimated nongeneralizable change attributable to congruence (i.e., representativeness reduction) would significantly reduce the average magnitude of effect.

Annual bluegrass (Poa annua L.) is a problematic weed in turfgrass that has evolved resistance to twelve different herbicide sites of action. The mitotic-inhibiting herbicide pronamide has both pre- and post-emergence activity on susceptible annual bluegrass populations. Still, post-emergence activity may be compromised in some resistant populations due to the lack of root uptake or an unknown foliar resistance mechanism. Spray droplet size may affect foliar and soil deposition of pronamide, thus potentially explaining variation in population control or differential foliar and root uptake. Pronamide, flazasulfuron, and pronamide + flazasulfuron deposition were quantified on annual bluegrass as affected by spray-droplet size. The efficacy of these herbicide treatments in resistant (R) and susceptible (S) annual bluegrass populations was then evaluated with two droplet sizes (400 and 1000 μm). Absorption and translocation of pronamide were investigated in R and S populations following foliar-only and soil-only pronamide applications.

No description available.

In a single capture-recapture problem, two new Wilson methods for interval estimation of population size are derived. Classical Chapman interval, Wilson and Wilson-cc intervals are examined and compared in terms of their expected interval width and exact coverage properties in two models. The new approach performs better than the Chapman in each model. Bayesian analysis also gives a different way to estimate population size.

No description available.

This investigation provides a comprehensive analysis of entrained-flow biomass combustion processes. Experimental and theoretical investigations indicate how particle shape and size influence biomass combustion rates. Experimental samples include flake-like, cylinder-like, and equant (nearly spherical) shapes with similar particle masses and volumes but different surface areas. Samples of small (less than 500 µm) particles were passed through a laboratory entrained-flow reactor in a nitrogen/air atmosphere and a maximum reactor wall temperature of 1600 K, while large samples were reacted in suspension in a single particle furnace operated at similar conditions as the entrained-flow reactor. A separately developed computer and image analysis system was used to determine particle surface-area-to-volume ratios based on three orthogonal particle silhouettes. Experimental data indicate that equant (spherical) particles react more slowly than the other shapes, with the conversion time ratio required for complete combustion becoming greater as particle mass increases and reaching a factor of two or more for particles larger than 1 mm in diameter (which includes most particles in commercial application). A color-band, non-contact pyrometer developed in this project measured particle surface temperatures and flame temperatures during pyrolysis and char burning processes. This technique employs widely available and relative inexpensive cameras and detectors. The camera-measured temperature data agree with black body calibration data within the accuracy of the data (± 20°C) and with thermocouple-measured data and model predictions within the repeatability of the data (± 50 °C) in most cases. A one-dimensional, transient particle combustion model simulates the drying, pyrolysis, and char oxidation and gasification processes of particles with different shapes. The model also predicts the shrinking/swelling and surrounding flame combustion behaviors of a single particle. Model simulations of the three shapes agree nearly within experimental uncertainty with the data. For biomass particle devolatilization processes, model predictions extended to a wider range of sizes predict the effects of shape and size on yields and overall mass conversion rates. The near-spherical particle loses mass most slowly and its conversion time significantly differs from those of flake-like particles and cylinder-like particles as particle equivalent diameter increases. Little difference exists between cylinder- and plate-like particles.

A method to incorporate grain size effects into crystal plasticity is presented. The classical Hall-Petch equation inaccurately predicts the macroscopic yield strength for materials with non-equiaxed grains or materials that contain unequal grain size distributions. These deficiencies can be overcome by incorporating both grain size and orientation characteristics into crystal plasticity theory. Homogenization relationships based on a viscoplastic Taylor-like approach are introduced along with a new function, the grain size and orientation distribution function (GSODF). Estimates of the GSODF for high purity α-titanium are recovered through orientation imaging microscopy coupled with the chord length distribution. A comparison between the new method and the traditional viscoplastic Taylor approach is made by evaluating yield surface plots.

Negative body image and preoccupation with weight are the norm for most women and girls in Western society, despite their potentially harmful consequences for psychological and physical wellness. While we know that many in this population experience negative feelings towards their bodies, we do not know if their beliefs about their body size are accurate and what effect a correct or incorrect assessment of one's body size has in terms of actual behavior. I examine this question among adolescent girls using data from the 2002 Health Behaviors in School-Age Children Survey. With a sample of 2,784 girls between the ages of 11 and 17, I run Poisson regression models to assess the relationship between actual and perceived body size and healthy versus unhealthy weight control behaviors, controlling for a number of indicators known to be associated with weight control, including parent and peer relationships, media exposure, and age of first menstruation. Results indicate that a discrepancy between actual and perceived body size is associated with increases in both positive and negative weight control behaviors, though the association with negative weight control behaviors is much larger. Starting puberty later is associated with a decrease in both types of these behaviors. Difficult family relationships appear to be more strongly associated with negative weight control than positive weight control. Other associations are discussed and suggestions for future research are offered.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has risen to among the top tier techniques for the direct analysis of solid samples. However, significant problems remain that must be solved to achieve the full analytical potential of LA-ICP-MS. Inefficient conversion of aerosol to ions within the ICP or transmission through the MS interface may decrease precision, sensitivity, and/or accuracy. Although fundamental mechanisms that govern ion production and transmission have been studied extensively in solution-nebulization (SN) ICP-MS instruments, significant gaps in our understanding remain. Furthermore, it is unclear to what extent differences between the aerosols generated during SN and LA influence either ion production or transmission. In this work, I initially investigated differences in the spatial distributions of Ca, Ba, and Sc ions generated by LA and SN using high-resolution LIF imaging. Ions formed from aerosol generated by LA at low fluence were distributed over much greater axial and narrower radial distances than SN aerosol. Additionally, I investigated the effects of solvent, laser fluence, and ablation atmosphere (He vs Ar) on ion distributions in the ICP. Unlike solvent, changing laser fluence and ablation atmosphere produced considerable changes in the ion signal intensity and spatial distribution during LA. At greater laser fluence, the radial distance over which ions were distributed dramatically increased. Surprisingly, when helium was mixed with argon as carrier gas, ion signals decreased. Many of these effects were assumed to be related to changes in the number and size of particles generated during LA. In a follow-up study, relative contributions to ion densities in the ICP from particles of different sizes were investigated. LIF images were recorded while filtering particles above a threshold size on-line. Micron-sized particles contributed the majority of ions formed in the ICP. For Ba, Ca, and Sc, differences in the axial position where nanometer- and micron-sized particles vaporized were 2, 1, and less than 1 mm, respectively. I also performed experiments to identify changes in the ion signal related to changing ablation conditions vs. changing ICP conditions associated with helium additions to the carrier gas. LIF images were recorded during different combinations of He/Ar added upstream and/or downstream of the ablation cell. Changes in the ion signal during ablation in helium vs argon did not always match expectations based on changes in particle numbers and sizes measured with SEM. The results force re-examination of some of the fundamental assumptions about the effect of carrier gas composition on the performance of LA-ICP-MS. The research described in this dissertation provides valuable insight into fundamental aspects of key ICP processes related to LA generated aerosol.