This dissertation consists of three essays which apply the tools of economic analysis to the professional baseball industry. The first essay analyzes the effect of minority status on the survival of Major League Baseball managers. Using survival time analysis based on data from 1985 to 2006 it is shown that minorities are 9.6 percentage points more likely to return the following season than white managers with the same performance and personal characteristics. ^ The second essay analyzes the effect of race on the probability of a former Major League Baseball player becoming a manager. Probit models with sample selection correction are estimated using data on the performance and personal characteristics of players from 1955 to 2007. It is shown that given the same performance, personal characteristics, and popularity black former players are 70 to 82 percent less likely to become Major League managers than white former players. ^ The third essay uses data envelopment analysis to examine how efficiently Major League Baseball teams produced wins from 1986 to 2005. It is shown that on average both National and American League teams over allocate the most resources to first basemen. Additionally, on average National League teams under allocate the most resources towards starting pitching while American League teams under allocate the most resources toward second base.
Cardiovascular diseases are the main cause of death in the United States. Most of treatments that are currently used are low-fat diet (LFD) and statins. However, alternatives have been proposed such as low-carbohydrate diets (LCD) and other drug treatments such as the use of inhibitors of secretory phospholipase A2 (i-sPLA2). Thus, in order to test whether they are an adequate alternative, two guinea pig studies were conducted. ^ The first study evaluated the effect of an i-sPLA2 on the prevention of atherosclerosis. The association of elevated levels of sPLA 2 in patients with cardiovascular diseases and their presence in atherosclerotic lesions suggest the participation of sPLA2 in this disease. Twenty-four guinea pigs were fed an atherogenic diet for twelve weeks. Half of them were treated with A-002, the i-sPLA2. The other animals were used as control. There was no difference on plasma lipids between groups, however, there was less inflammation (p\u3c0.05) in aorta from the i-sPLA2 group. This group had a reduction in cholesterol in aorta compared with control group. Therefore, A-002 prevents atherosclerosis.^ The second study evaluated whether LCD prevent atherosclerosis. Since satiety positively affects the results of dietary interventions, the effects of LCD on appetite hormones were compared to those of LFD. Animals were subjected to LCD or LFD for 12 weeks. The LCD group gained while animals fed LFD lost weight. The amount of food intake was not different suggesting that food density and gastric distension played a role in satiety. There was no difference in leptin levels, which excludes the hypothesis of leptin resistance in the LCD group. However, the heavier animals that were fed LFD had impairment in insulin sensitivity, which was not observed in those fed LCD. Thus, the association between weight gain and insulin resistance seems to be dependent on high carbohydrate intake. ^ The effects of both LCD and LFD on atherosclerosis were also evaluated. LDL-cholesterol, aortic cholesterol, aorta oxLDL and inflammatory cytokines were lower in the LCD compared to the LFD group (p\u3c0.05). Histological analyses supported these findings. In conclusion, both LCD and i-sPLA 2 are able to efficiently prevent atherosclerosis through different mechanisms.
A phenomenological study was conducted to describe the lived experience of non-nurse college graduates in an accelerated registered nurse (RN) education program designed for completion in less than 11 months. A purposive sample of 11 participants who recently completed the program shared their experience in lengthy, structured face-to-face interviews. Eight themes emerged: (1) a whirlwind forecasted in advance but surprisingly unimaginable; (2) awakening to the harsh realities of nursing through personal encounters with patients; (3) the transformation from expert to novice feels like being deer in the headlights ; (4) mentoring from clinical instructors, passionate professors, and staff nurses is highly valued; (5) the journey to the finish line ranges from easy to difficult depending on their previous career; (6) students expect continuous quality improvement in the program; (7) class comradery and the development of friendships ease the stress; and (8) overall graduates liked the program as they believe that are better prepared to enter the workforce than traditionally educated nurses. ^ Describing the lived experience is based on the philosophical underpinnings of Husserl\u27s descriptive phenomenology. The participants\u27 shared experiences contain eidetic structures that emerged from the data using Colaizzi\u27s method of data analysis. Describing the experience is a foundation for further knowledge development. Currently, there is a paucity of research concerned with second degree programs. The number of accelerated RN programs for non-nurse college graduates has risen from 31 in 1998 to 205 in 2007, with many more in the planning phase (AACN, 2007). A science of nursing education for adult learners with previous college degrees in accelerated programs is warranted. Educators, administrators, and employers need to be certain that teaching strategies are appropriate to the learners\u27 needs and that the graduates are being socialized into nursing.
Toward using more ecologically valid emotion displays in brain research: A functional neuroimaging study of the Communication of Affect Receiving Ability Test
This research used spontaneously generated, dynamic emotion displays in an experimental task for brain imaging, and produced theoretically meaningful results in the limbic system and right hemisphere neocortical areas associated with action simulation. The Communication of Affect Receiving Ability Test (CARAT), an instrument that consists of 40 ten-second videos of senders displaying four different types of affect, was given to 38 subjects in the fMRI scanner. Subjects were asked to judge if the sender was viewing someone familiar, something scenic, something unpleasant, or something unusual. Results of a conjunction analysis of hemodynamic responses to the four categories versus a resting baseline showed that there was activation of limbic system circuits in the amygdala-hippocampal area, insula, and anterior cingulate for all categories, as well as right hemisphere activation in the temporal-parietal junction and premotor area/inferior frontal gyrus. Results also showed that when the neutral category (Scenic) was subtracted from the Familiar, Unpleasant, and Unusual categories, there were distinct patterns of limbic system and neocortical activation unique to each. The discussion considers how these patterns of activation add to what is currently known about the way the brain processes emotion displays, and how the use of a more naturalistic display may have influenced the results. Implications for future research on empathy are reviewed.
Hypoxia stress causes defective heart morphogenesis. Under hypoxia, hydroxylation of HIF-α proteins by prolyl hydroxylase domain containing proteins (PHDs) is inefficient, allowing them to accumulate to high levels by escaping von Hippel Lindau protein (VHL) dependent polyubiquitination and proteasomal degradation. This thesis examines how PHDs and VHL, which are important for oxygen sensing and oxygen dependent degradation of HIF-α, regulate coronary vascular patterning and myocardial development. When Phd2 was specifically deleted in the myocardium by Nkx2.5Cre, overt heart defects did not occur but modest coronary vascular defects were found. In contrast, Nkx2.5Cre-mediated triple knockout of Phd1, Phd2 and Phd3 caused heart defects similar to those reported for hypoxia-stressed embryos, such as thin myocardial compact layer and ventricular septation defects. Nkx2.5Cre-mediated knockout of Vhl resulted in similar heart defects. In either VHL or triple PHD deficient hearts, coronary vascular patterning was defective. Coronary vascular networks covered smaller areas, and failed to evolve into mature vascular trees with distinct large and small vascular branches. In avascular areas, there were numerous CD31+/VEGFR-2+ foci, suggesting failure of endothelial cells to organize into vascular structures. Dye injection into embryonic circulation confirmed that cardiac tissues in VHL or triple PHD deficient hearts were poorly irrigated. These data indicate the essentiality of the myocardial oxygen sensing mechanism to regulate HIF-1α levels. Hyperactive HIF signaling in the myocardium interferes with normal coronary vascular patterning, which in turn hinders myocardial development. It is likely that this mechanism is also operational under hypoxia stress.
This dissertation investigates three problems in trajectory prediction and passive sensor network data association that are challenging and very relevant in today\u27s world. ^ The first one is the impact point prediction (IPP) of ballistic objects such as mortar and howitzer projectiles. A multiple model procedure is presented to estimate the state of a ballistic object in the atmosphere and identify it using radar measurements from the initial part of the trajectory only, for the purpose of IPP for use in area defense. Measurements are taken during the first part of its trajectory up to the apogee and the final state estimate obtained by the multiple model estimator is then predicted to its impact point on earth. ^ The second problem considered is the problem of using passive (line-of-sight angle) observations of a surface-to-air or an air-to-air missile (pursuer) from an aircraft (evader) to infer whether the missile is aimed at the aircraft. The observations are assumed to be made only on an initial portion of the pursuer\u27s trajectory. The approach is to model the trajectory of the missile with a number of kinematic and guidance parameters, estimate them and use statistical tools to infer whether the missile is guided toward the aircraft. The estimation/decision algorithm developed can be used for an aircraft to decide, in a timely manner, whether appropriate countermeasures are necessary. ^ The third area is feature-aided tracking of ground vehicles using acoustic signals obtained by a passive sensor network. Tracking of a moving ground target using acoustic signals obtained from a passive sensor network is a difficult problem as the signals are contaminated by wind noise and are hampered by road conditions and multipath, etc., and are not deterministic. Multiple target tracking becomes even more challenging, especially when some of the vehicles are wheeled (e.g., cars/trucks) and some are tracked (e.g., tanks), and are closely spaced. In such cases the stronger acoustic signals from the tracked vehicles can mask those from the wheeled vehicles, leading to poor detection of such targets. Acoustic sensor arrays obtain direction of arrival (DoA) angle estimates of such emitters from the received acoustic signals. The full position estimates of targets, obtained following the association of the DoA angle estimates of the same target from at least three sensor arrays, are used for target tracking. However, because of the particular challenges encountered in multiple ground vehicle tracking, this association is not always reliable and thus, target tracking using full position measurements only is difficult and it can lead to lost tracks. We developed a new feature-aided tracking algorithm in order to improve the tracking performance.
The diffusivity and intrinsic diffusivity of multicomponent alloys can be determined from diffusion couple experiments, when concentration differences in each diffusion couple are small, by using the Square Root Diffusivity analysis. However, this analysis assumes that the diffusivity is independent of composition. Therefore an important question is what diffusivity is produced by the Square Root Diffusivity analysis when applied to real systems that normally have variable diffusivity. The present study investigates this question with perturbation theory and a numerical analysis. The results show clearly that the Square Root Diffusivity analysis gives the diffusivity at the average composition with negligible error as long as the diffusivity is linearly dependent on concentration and the data is analyzed with respect to the Matano plane. Also, analyses are presented that shows how the error is affected by diffusion couple design and by symmetric pairing of data.^ In another study, it is shown how the Square Root Diffusivity equations can be used to model diffusion phenomena in constant intrinsic diffusivity systems, e.g. thermodynamically ideal solutions. This work extends a previous model by van Loo to higher order systems.^ The diffusivities of Ni-4at%Cr-6at%Al-4at%Mo quaternary alloy at 1100$\sp\circ$C and 1200$\sp\circ$C were determined from three diffusion couples at each temperature with the Square Root Diffusivity analysis. By combining equations from the Square Root Diffusivity analysis and the analysis proposed by Krishtal et al., the diffusivity was also obtained from two diffusion couples and the results were compared with three couple values.^ Finally, the intrinsic diffusivities at 1200$\sp\circ$C were measured with the diffusivities and marker movement data. However the intrinsic diffusivities were subject to a relatively large error under the present experimental conditions.
In this thesis I characterize a component of information carried by neural signals used in the perceptual system in the formation of spatial representations. I call that component of information “bodily information”. My claim is that in perception (in us and other terrestrial creatures), any information transferal from outside to inside the head has two components of variation, and bodily information is carried by one of those components. Bodily information has the character of measuring the body, and that measurement of the body is necessary for perceptual spatial perception. ^ Describing spatial perception in this way allows me to explain and predict otherwise perplexing phenomena, such as certain disruptions to the representation of space as found in spatial disorders and in artificial lab conditions. Describing the pick up and transfer of spatial information in term of bodily information also allows me to make a further claim in which I characterize the activity of certain processes in the brain as engaging in a form of identification.
NG2 cells are a novel and unique cell population in the central nervous system. They were identified as the fourth type of glial cells, but their role as progenitor cells has not been well defined. Using newly generated transgenic mouse lines, we analyzed the fate of NG2 cells in vitro and in vivo, and demonstrated that NG2 cells are committed to glial lineage throughout development. ^ We purified NG2 cells from neonatal NG2DsRed BAC transgenic mice and found that NG2 cells give rise to oligodendrocytes, astrocytes but not neurons in vitro. Using NG2creBAC:ZEG double transgenic mice, we demonstrated for the first time that NG2 cells generate oligodendrocytes throughout the brain and a subset of protoplasmic astrocytes in ventral gray matter but not in dorsal neocortex or corpus callosum. NG2 cells generate some gray matter astrocytes in spinal cord but not in cerebellum. Neurons are not derived from NG2 cells, but some cortical neurons in the adult brain express the reporter due to the transient expression of Cre in these neurons. ^ Analysis on NG2creERTMBAC:ZEG double transgenic mice revealed that postnatal NG2 cells continuously generate oligodendrocytes even in the mature brain, and that the ability of NG2 cells to differentiate into oligodendrocytes declines with age. NG2 cells in the embryonic brain but not in the postnatal brain are capable of generating protoplasmic astrocytes in the ventral forebrain. Clusters of cells that arise from single NG2 cells in the postnatal brain are heterogeneous, containing pure oligodendrocytes, pure NG2 cells or both. ^ When the transcription factor Olig2 was deleted specifically in NG2 cells, NG2 cells predominantly generated astrocytes especially in the dorsal neocortex and corpus callosum at the expense of oligodendrocytes, indicating that the fate of NG2 cells toward oligodendrocytes or astrocytes can be switched by Olig2. ^ In summary, we clarified the fate of NG2 cells which had been under long debate and discovered an important regulatory mechanism underlying the differentiation of NG2 cells. Our work establishes the framework for understanding the progenitor property of NG2 cells so that the therapeutic function of NG2 cells can be better evaluated and applied to neurological diseases.
Lyophilization is a process often used to stabilize labile molecules in the solid-state. The process of lyophilization presents many obstacles for formulation development due to the nature of the process, which involves a freezing step, followed by sublimation of ice, and removal of unfrozen water at a higher temperature. During the freezing process, nucleation and growth of ice with simultaneous concentration of the solute in the non-ice phase occurs. The impact of the concentration effect and cold temperatures on amorphous phase behavior during the lyophilization process has not been extensively studied and is therefore not well understood. This has mainly been due to limitations in methods of detection. Current methods of detection have been mainly limited to the detection of multiple glass transitions using DSC and visual observation of the freeze-dried cake using SEM. The occurrence of amorphous phase separation in freeze-dried solids and methodology for detection is reviewed. Evaluation of a novel Raman mapping technique and a simple analysis of the data using model PVP/dextran systems revealed the ability of the technique to identify phase separation in freeze-dried samples. The results of the analysis were evaluated based on DSC, i.e. detection of multiple Tg\u27s in the freeze-concentrate, and were found to be comparable where limitations were acknowledged for both techniques on the boundaries of phase separation. Estimates of phase compositions were determined and were found to be qualitatively in agreement between DSC and Raman. Pair distribution function analysis (PDF) of x-ray powder diffraction (XRPD) data confirmed the results observed by Raman and detected phase separation in some samples below the limit of detection of either Raman or DSC. The Raman technique was applied to model protein-stabilizer systems. Phase separation was identified in all mixtures of Ficoll/BSA and in 1:1 and 3:1 trehalose:lysozyme samples, thus demonstrating the potential of Raman to be used in screening for phase separation in protein formulations. Thermally stimulate current spectroscopy (TSC) was also evaluated as a potential tool for amorphous phase separation. TSC analysis confirmed to presence of phase separation in polymer systems with the surprising observation of largely different glass transition temperatures than DSC. Speculations of the nature of artifacts presented in TSC spectra are discussed. Lastly, in an effort to elucidate some of the parameters which control the process of phase separation during freezing, nucleation temperature and cooling rate were studied in the absence of thermal history effects and compared to a sample mimicking the product temperature profile of a freeze-dried vial. Cooling rate and nucleation temperature, alone, were found to have a minimal effect on phase separation. The largely important factor of thermal history dominated any other effects. Thus, control of the process of phase separation can be achieved through sample volume and nucleation temperature while considering the presence of a thermal gradient in a vial.