High-dimensional data offers researchers increased ability to find useful factors in predicting a response. However, determination of the most important factors requires careful selection of the explanatory variables. In order to tackle this challenge, much work has been done on single or grouped variable selection under the penalized regression framework. Although the topic of variable selection has been extensively studied under the parametric framework, its applications to more flexible nonparametric models are yet to be explored. In order to implement the variable selection in nonparametric additive models, I introduce and study two nonconvex selection methods under the penalized regression framework, namely the group MCP and the adaptive group LASSO, aiming at improvements on the selection performances of the more widely known group LASSO method in such models. One major part of the dissertation focuses on the theoretical properties of the group MCP and the adaptive group LASSO. I derive their selection and estimation properties. The application of the presently proposed methods to nonparametric additive models are further examined using simulation. Their applications to areas such as the economics and genomics are presented as well. Under both the simulation studies and data applications, the group MCP and the adaptive group LASSO have shown their advantages over the more traditionally used group LASSO method. For the proposed adaptive group LASSO that uses the newly proposed weights, whose recursive application is therefore never studied before, I also derive its theoretical properties under a very general framework. Simulation studies under linear regression are included. In addition to the theoretical and empirical investigations, throughout the dissertation, several other important issues have been briefly discussed, including the computing algorithms and different ways of selecting tuning parameters.

The need for effective energy harvesting from renewable resources becomes increasingly important, especially in the light of the inevitable depletion of the fossil fuel energy sources. Among renewable energy sources, wind energy represents one of the most attractive alternatives. In this thesis, we construct several stochastic optimization models, including the traditional risk-neutral expectation based model, and risk-averse models based on linear and nonlinear coherent measures of risk, to study the strategic planning and operation of futuristic power grids where the loads are served from renewable energy sources (wind farms) through High Voltage Direct Current lines. Exact solutions algorithms that employ Benders decomposition and polyhedral approximations of nonlinear constraints have been proposed for the formulated linear and nonlinear mixed-integer optimization problems. The conducted numerical experiments illustrate the efficiency of the developed algorithms, as well as effectiveness of risk-averse models in reducing the power grid's exposure to power shortage risks when the energy is produced from renewable sources. We further extend the risk-averse models to demonstrate how energy storage devices may impact the risk profile of power shortages in the renewable energy power grid. Additionally, we consider convex relaxations of optimal power flow problem over radial networks, that allow for solving mixed-integer optimization problems in traditional alternating current distribution networks. Exactness of a specific second-order cone programming relaxation has been discussed. We finally propose an “ extended” optimal power flow problem and prove its second-order cone programming relaxation to be exact theoretically and empirically.

Learning to escape aversive stimuli and effectively predicting the consequences of different cues provides animals with an increased chance of survival. Discriminative avoidance conditioning affords the opportunity to examine these specific behaviors. The present experiment investigated the influence of a visual signal on an auditory discriminative active avoidance conditioning task. Building on the work of Gabriel and colleagues (Freeman et al., 1997; Poremba and Gabriel, 1997, 1999), originally conducted in rabbits, an adaptation of the discriminative active avoidance paradigm was implemented using male rats. Animals were trained to avoid a signaled shock (US) by spinning a small wheel during an auditory cue, the positive conditioned stimulus (CS+). A second auditory cue signaled the absence of shock, the negative conditioned stimulus (CS-). A visual safety signal was added following a correct response to the CS+ (successful avoidance of the shock). Three groups were formed based on experience with the visual safety signal: animals that never had training with the visual signal, animals that had the visual signal added during their training, and animals that began training with the visual signal. Animals trained with the visual safety signal showed a decrease in the number of days need to learn the task and the percentage of animals that learned the task increased. These results suggest that a visual safety signal enhances learning during an auditory discriminative avoidance conditioning task. This task will be used to expand exploration of the active avoidance neural circuitry and investigate the circuitry underlying the visual safety signal.

Communication, involves the skill and craftsmanship of an aspiring artist to investigate the possibilities within. Interaction and communion with the world is amplified by practice of breathing in, during multiple circumstances. Acting is reacting to the world and the multiple microcosms in it. But why is this important, why is this necessary, why is there a need to act, to live truthfully under imaginary circumstances? This University is a place that has given me the opportunity to investigate these curiosities. Not everyone has the opportunity to commit to the investigation of what it means to breathe in the atmosphere in a specific context and to respond with impulse in forms of both sound and movement. This process is investigating what it means to find truth in oneself in response to the space, time, and people. The investigating is of what it means to be, rather than to manipulate a world that caters to the ego, in truth the ego must dissipate. I came here with ideas and determinations, but all of this anticipatory preparation is what I had to let go of in pursuance of truth and the development of a craft. I used to believe my time here was an end point that would lead me to a goal. It is not; it is an introduction to the rest of my life. I am a student now and forever. I encourage the reader to take one thing, consider what it means to be a life long learner.

Orthodontic materials are evolving. The aim was to find out how this affects treatment outcomes. Brackets are getting smaller and smaller in the name of esthetics and patient comfort. The aim of this study was to find out if intrabracket width (the horizontal distance between bracket tie wings) had any effect on maxillary anterior root torque. We also aimed to find out if three common orthodontic archwires were capable of delivering the torque necessary to achieve ideal root torque. A machine was developed to simulate lingual root torque of an upper central incisor. This is the first test of its kind, presumably because intrabracket width is thought to have no effect on torque. It was found that all three archwire groups were capable of delivering the torque needed to accomplish treatment goals. Torque was found in this experiment to be expressed differently in wide and narrow brackets. The wider bracket required less torque in the archwire to produce the same force compared to that in a narrow bracket. The implications of this finding are that orthodontists may need to adjust the torque being placed in archwires based upon the intrabracket width of the brackets they are using.

Plasma cell neoplasms (PCN), including multiple myeloma, are tumors of terminally differentiated B cells. Despite a significant research effort, and numerous advances in therapy, most tumors of this B cell lineage remain incurable. To this end, understanding factors which are critical for the development of PCN may lead to new avenues for therapy. Interleukin-6 (IL-6) is a pleiotropic, pro-inflammatory cytokine which supports the growth, proliferation, and survival of myeloma cells. We found that inflammation, and in particular, IL-6 is critical for the development of PCN. In order to determine if tumor microenvironment (TME) or B cell-derived IL-6 was more important in PCN development, we utilized an adoptive transfer system of tumor formation. By adoptively transferring premalignant B cells into recipients, and then providing the B cells with an inflammatory microenvironment through the use of pristane, we were able to generate donor tumors in recipient mice. Utilizing this method, a series of adoptive transfers were performed to determine the primary source of IL-6 in murine PCN development. We discovered that TME-derived IL-6, and not B cell-derived IL-6, is most critical for PCN development. Furthermore, in studying the lesions in B cell development which lead to tumor formation, we discovered that IL-6 collaborates with the proto-oncogene c-Myc in spontaneous germinal center (GC) formation. The spontaneous GCs were accompanied by a robust follicular T helper cell response. In characterizing the genetic lesions which lead to the GC formation, we discovered that Myc-transgenic mice develop a significant increase in the population of B1a B cells. Furthermore, these B1a B cells infiltrate the spontaneous GCs of double transgenic Myc/IL-6 mice. Lastly, utilizing our adoptive transfer method, we determined that the germinal center response is necessary for the development of PCN in mice. Lastly, we focused our efforts on another oncogene which collaborates with IL-6, BCL-2. Double transgenic BCL-2/IL-6 mice develop PCN and spontaneous GCs. Of interest however, the adoptive transfer of BCL-2/IL-6 B cells results in tumor formation without the use of pristane. Furthermore, the adoptive transfer recipients develop bone lesions, hind limb paralysis, and a monoclonal gammopathy. This model closely recapitulates many of the pathophysiological features seen in human PCN. This new model promises to be important for future studies into PCN development and treatment.

Surrendering to what is the nature of compassion, the power of silence, a true commitment to the character, a complete freedom of the imagination, and the will, at any given moment, to let go of who we think we are in order to become who we are meant to be - has been the greatest teacher of all. .-Eckhart Tolle

The purpose of this study was to investigate if different ways of treating missing responses affects the IRT item parameters and vertical scales. An empirical study was conducted with the verbal test and quantitative test of a large-scale ability test for grades 4 through 12. Five commonly used methods for scoring missing responses were investigated: Listwise deletion (LW), scoring as incorrect (IN), scoring as not-presented (NP), treating omitted items as incorrect and not-reached items as not-presented (INNR), and assigning a partial score (BN). In addition, three multiple imputation methods that show promising results outside of IRT were investigated: multiple imputation using stochastic regression with data augmentation algorithm (MISR), multiple imputation by chained equations (MICE), and multiple imputation under two-way imputation with error (MITW). The effect of missing data treatments were investigated with both concurrent and separate calibrations and with three proficiency estimators including EAP, MLE, and QD. The vertical scale was evaluated based on the three properties including grade-to-grade growth, within-grade variability, and effect size. The impact of missing data treatments on the item parameter estimates was also examined by comparing the summary statistics for item discrimination, item difficulty, and pseudo guessing. Lastly, the practical impact was investigated by comparing raw-to-scale score conversion tables. The results showed that different ways of handling missing responses affect the resulting item parameter estimates and vertical scales. In general, IN produced higher item discrimination and item difficulty parameter estimates, but yielded lower pseudo-guessing parameter estimates compared to other missing data treatments. IN also produced higher mean theta estimates and larger growth while MITW yielded smaller theta estimates and growth. MICE and MISR tended to perform similarly to INNP and NP. The choice of missing data treatment had a greater impact on the results with separate calibration than concurrent calibration, and with MLE than EAP or QD. In addition, missing data treatments had a larger effect on low and high item difficulty estimates than items with middle range difficulty estimates, and yielded differences in developmental scale scores in particular at both ends of the score scale.

Music often evokes strong emotions, such as excitement, joy, and nostalgia. These emotions can be highly pleasurable and accompanied by increased physiological arousal. Pleasure-inducing music activates a network of brain regions including the medial prefrontal cortex (mPFC), striatum, and amygdala. In Experiment 1, I explore the neural structures critical for music-evoked pleasure. I hypothesize that individuals with damage to brain regions involved in emotional responses to music (e.g., mPFC, striatum, amygdala) will show a decrease in their pleasurable responses to music after brain injury. Patients from the Iowa Neurological Patient Registry completed questionnaires that assessed current emotional responses to music and changes in emotional responses to music after brain injury. The results provided partial support for the hypothesis, and the most striking loss of musical pleasure (referred to as "music anhedonia") occurred in a patient with damage to the striatum. However, musical pleasure appears to be relatively resistant to brain damage, as music anhedonia was only observed in a few individuals with varying regions of brain damage. Along with strong emotions, music often triggers distant memories. However, the mechanism underlying music-evoked autobiographical memories (MEAMs) has not yet been investigated. Here, I predict that emotion is a central aspect underlying MEAMs. In Experiment 2a, I tested the hypothesis that MEAMs are more emotional and vivid than autobiographical memories evoked by pictures of famous faces. Neurologically normal, healthy adults viewed pictures of famous faces and listened to music while electrodermal activity was recorded. After each stimulus, participants described any memories that were evoked. Supporting my prediction, I found that MEAMs were significantly more vivid than face-evoked memories. In addition, music that evoked memories was accompanied by increased skin conductance responses compared to music that did not evoke memories. In Experiment 2b, I used a neuropsychological approach to test the prediction that neural regions underlying music-evoked emotions are also critical for MEAMs. I tested the hypothesis that individuals with damage to brain regions important for music-evoked emotions (mPFC, amygdala, and striatum) would have impaired MEAMs. Individuals with damage to these regions, brain-damaged comparison subjects (with damage to other regions) and neurologically normal comparison subjects completed the same task as in Experiment 2a. The results indicated partial support for the hypothesis, showing that individuals with mPFC, but not striatal, damage had slightly decreased MEAM vividness. Additionally, individuals with damage to the striatum and mPFC showed a disconnect between emotional ratings and physiological responsiveness. These findings provide important implications for the use of music in therapeutic settings. Since musical reward is predominantly preserved in individuals with brain damage, music can be used to improve mood and affect in clinical populations. In addition, these findings support the use of music as a memory aid in patients with dementia, since music-evoked memories are shown to be more vivid than memories evoked by other cues. Together, these experiments provide partial support for the hypothesis that neural regions important for emotion are also critical for MEAMs, indicating that emotion may be an important aspect underlying music-evoked autobiographical memories.

In order to verbally communicate successfully, people need the ability to retrieve a desired word. However, the inability to do this, called “anomia,” is a common impairment for people with aphasia, and frequently persists into the chronic stage of recovery. Strategies that facilitate verbal expression may reduce or compensate for instances of anomia. Verbal strategies, such as Semantic Feature Analysis (SFA) have been researched extensively and shown to be effective. Nonverbal strategies, such as drawing and gesture, have research on their effects as a substitution for verbalization, but less on their facilitative effects. However, the research suggests they may work in a similar manner to verbal approaches, by activating semantic networks. Thus, the facilitative effects of nonverbal strategies should be explored further. The aim of this experiment was to determine the facilitative effects of drawing and gesturing during a picture naming task in one participant with chronic aphasia. Results revealed that all conditions evaluated, drawing, gesture, and wait (control), produced improvements in the picture naming task. However, contrary to expectations, the facilitated conditions (i.e. drawing and gesture) did not create more effects than the unfacilitated condition (i.e. wait). This finding may indicate the benefits of a factor common to all conditions. Further results of this study and directions for future research are discussed.