Indiana University-Purdue University Indianapolis (IUPUI) / The current study examined African American participants’ perceptions of and reactions to a White ally vs. a Black target (vs. a no confrontation control condition) prejudice confrontation. Based on intergroup helping theories suggesting that low-status group members question high-status helper motivations and consequently feel disempowered by their help (Fisher, Nadler, & Whitcher-Alagna, 1982; Nadler, 2002), we predicted that participants would report lower empowerment when a White vs. Black person confronted on their behalf, and that perceived confronter motivation would mediate the effect of confronter group membership on empowerment. To test these hypotheses, we recruited African American participants (N = 477) via Amazon’s Mechanical Turk, randomly assigned them to either a no confrontation control, target confrontation, or ally confrontation condition, and then assessed participants’ sense of psychological empowerment and perceptions of the confronter’s motivation. The results supported our predictions for the primary dependent variables, and mediation analyses provided evidence for a causal model such that confronter group membership affected participants’ psychological empowerment via their perceptions of the confronter’s motivation. The findings suggest that although both target and ally confrontations are preferable to no confrontation, allies should be aware of the possible disempowering effect of their confronting on targets of prejudice and the importance of their own motivations when engaging in prejudice confrontation. The current study further emphasizes the importance of representing targets’ perspectives in studies of prejudice.

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The purpose of this dissertation was to establish how vibrotactile guidance cues can be used to improve marksmanship. This work originated in an effort to provide covert communication, navigation, and weapon aiming cues for infantrymen. It is predominantly an application-driven investigation rather than driven a priori by specific theoretical predictions from models of human performance. Three experiments are presented. Experiment 1 established the affect on initial response to vibrotactile guidance cues of tactor placements on the palmer versus dorsal surface of the hand, and targets appearing left versus right of center. Results suggest that tactile cues provided on the left side of the medial line of the hand afford moving the hand to the left, while tactile cues provided on the right side of the medial line afford moving the hand to the right. Experiment 2 established the affect of continuous relative distance cues and on- versus off-target vibrotactile stimuli on reaction time and accuracy for target selection. Results indicated an interaction between the pulse rate of vibrotactile stimuli and the method used to highlight an "on-target" condition; the suppressed target condition was superior to the enhanced target condition when the pulse rate increased as the cursor moved closer to a target. Experiment 3 established if there are performance differences between discrete and continuous distance information for target selection, and investigated the interaction between the near-target pulse rate and on-target cues. Results indicate that maximizing the difference between near-target guidance cues and on-target cues reduces the target selection time, particularly when the near-target pulse rates are fast (ISI = 10 msec). The results also suggest that, as with vision, the vibrotactile off-target guidance cues are not necessary during the whole target selection task. Rather, the guidance cues can be provided only during the initial pop-up condition and during the sub-movements closing on the target.

Platanthera is one of the largest genera of temperate orchids and exemplifies a lineage that has adaptively radiated into diverse habitats within North America, Asia, Europe, North Africa, Borneo, and Sarawak. Major centers of diversity in this genus are western North America and eastern Asia. The diversity in floral morphological traits such as floral color, shape and the length of nectar spur is associated with numerous pollination syndromes, making Platanthera an ideal system to study the evolution of floral traits and pollination biology. Despite its diversity, a thorough phylogenetic hypothesis for the genus is lacking because no studies have yet sampled taxa exhaustively or developed a robust molecular toolkit. Nevertheless, in past phylogenetic studies some intrageneric groups of species appear to be monophyletic. One of these groups is subgenus Limnorchis, but the majority of taxa in this group have not been included in a phylogenetic analysis. In this study, I developed a new toolkit for Platanthera consisting of genomic information from 617 low-copy nuclear loci. Using a targeted enrichment approach, I collected high-throughput sequence data from these loci in 23 accessions, including nine of the 12 diploids of subgenus Limnorchis and nine outgroup Platanthera species. A maximum likelihood search was performed on a 570,818 nucleotide supermatrix to generate a phylogeny. This analysis resolved a strongly supported monophyletic clade for subgenus Limnorchis. This phylogeny was then used to test hypotheses of biogeographic diversification and floral trait evolution of subgenus Limnorchis. Ancestral biogeographic reconstruction indicated that subgenus Limnorchis originated in western North America ca. 3 – 4.5 Mya from an ancestor that was widespread in western North America and eastern Asia and subsequently diversified in western North America, followed by dispersal of some species to eastern North America. Floral macro and micro-morphological traits were characterized across the subgenus. Ancestral character reconstruction suggests convergent evolution of spur length, spur shape and viscidium shape, possibly in response to selection by similar pollinators. Understanding the biogeographic history and morphological diversification of subgenus Limnorchis within a phylogenetic context will contribute to an updated taxonomy for the subgenus.

GaSb is a semiconductor material having a narrow band gap in the infrared spectrum of 0.72 eV. This research is intended to investigate the low cost growth and properties of GaSb and to propose this material as a candidate for a cost effective method of developing a GaSb /silicon tandem solar cell. This work investigated the sputtering of GaSb films onto a glass substrate from a GaSb/Sb split-sputtering target. A GaSb compound was formed by placing Ga and Sb elements inside a vacuum sealed ampule. The ampule was placed inside a box furnace and heated at 800 0 C successfully forming a GaSb compound. Both GaSb and Sb were molded into a semicircular shape in a quartz container. X-ray diffraction (XRD) was conducted on sputtered films in order to confirm their structure. XRD peaks of the film were compared with reference peaks found on the Inorganic Crystal Structure Database (ICSD). GaSb peaks were apparent at specific sputtering chamber conditions of substrate temperature and source-to-substrate distance. Sputtered GaSb films were then further characterized with the Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and Hall Effect measurements. A theoretical thickness of the films was calculated using FTIR measurements to be about 1 μm and 0.35 μm for the films grown on a substrate heated with heater powers of 280 watts and 250 watts respectively. SEM confirmed the sample thicknesses with 20% error. Hall Effect measurements resulted in a high carrier concentration and low free carrier activation energy; 7.545 x1019 cm-3 and 0.1017 eV respectively. These values are attributed to the possible existence of anti-site defects. / Thesis / Master of Applied Science (MASc)

<p> In this thesis new joint target tracking and classification techniques for aspect-dependent measurements are developed. Joint target tracking and classification methods can result in better tracking and classification performance than those treating these as two separate problems. Significant improvement in state estimation and classification performance can be achieved by exchanging useful information between the tracker and the classifier. Target classification in many target tracking algorithms is not typically done by taking into consideration the target-to-sensor orientation. However, the feature information extracted from the signal that originated from the target is generally a strong function of the target-to-sensor orientation. Since sensor returns are sensitive to this orientation, classification from a single sensor may not give exact target classes. Better classification results can be obtained by fusing feature measurements from multiple views of a target. In multitarget scenarios, handling the classification becomes more challenging due to the identifying the feature information corresponding to a target. That is, it is difficult to identify the origin of measurements. In this case, feature measurement origin ambiguities can be eliminated by integrating the classifier into multiframe data association. This technique reduces the ambiguity in feature measurements while improving track purity. </p> <p> A closed form expression for multiaspect target classification is not feasible. Then, training based statistical modeling can be used to model the unknown feature measurements of a target. In this thesis, the Observable Operator Model (OOM), a better alternative to the Hidden Markov Model (HMM), is used to capture unknown feature distribution of each target and thus can be used as a classifier. The proposed OOM based classification technique incorporates target-to-sensor orientation with a sequence of feature information from multiple sensors. Further, the multi-aspect classifier can be modeled using the OOM to handle unknown target orientation. The target orientation estimation using OOM can also be used to find improved estimates of the states of highly maneuverable targets with noisy kinematic measurements. One limiting factor in obtaining accurate estimates of highly maneuvering target states is the high level of uncertainty in velocity and acceleration components. The target orientation information is helpful in alleviating this problem to accurately determine the velocity and acceleration components. </p> <p> Various simulation studies based on two-dimensional scenarios are presented in this thesis to demonstrate the merits of the proposed joint target tracking and classification algorithms that use aspect-dependent feature measurements.</p> / Thesis / Doctor of Philosophy (PhD)

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