Thesis (M.S.)--University of Michigan, 1955.

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Abstract The main goal of this study is to examine mechanisms controlling valley asymmetry development at two locations with distinctly differing environmental parameters and to develop a model for the two locations. As a secondary aim the knowledge gained from the main goal is thought to help understand the very uncertain glacial past of the high Drakensberg as it can be compared to the much accepted glacial history of Abisko. Parameters studied were slope angle, landforms, vegetation cover, block abundance, available moisture, bedrock characteristics, temperature and soil moisture. Some parameters were not studied in the field due to time issues; these were instead gathered by literature study. These parameters were structural weakness, soil depth and glaciation. Results show that the environmental differences noted between each sites north and south facing slope are clear. The side facing the equator is at both locations less steep, warmer and has more diverse vegetation. Temperature development with elevation was statistically analyzed and showed no correlation or not statistically significant correlation on all slopes. The expectation the south facing side of the Sani Pass transect showed where a statistically significant decline in temperature with elevation. The main conclusion drawn is that valley asymmetry development at both locations is controlled by the increased intensity of denudational processes on the side facing the equator as a result of the larger input of radiative energy there. It is also suggested that internal feedback mechanisms are related to the hastening of asymmetric development. The main constraint of the study is that not large enough data sets were gathered and that some important parameters like soil depth could not be included in the study. More research is needed in the field of vegetation’s role in interacting with physical processes on mountain slopes. The role of vegetation as an enhancer or retarder of geomorphic processes is not sufficiently understood. / Sammanfattning Denna studies huvuduppgift var att undersöka de mekanismer som kontrollerar uppkomsten av dalgångsasymmetri vid två områden som innehar vitt skilda naturliga förutsättningar och att skapa en modell för platserna. Informationen som ges från huvuduppgiften tros kunna hjälpa förstå den osäkra glaciala historien för Sani Pass eftersom den då direkt kan jämföras med Abiskos väldokumenterade historia. Undersökta parametrar vid båda platserna är sluttningsvinkel, landformer, vegetation, blockmängd, vattenmängd, berggrundskaraktär, temperatur och markfukt. Vissa parametrar kunde inte mätas i fält och fick därför hämtas från facklitteratur. Exempel på sådana parametrar är svagheter i berggrunden, jorddjup och glacial historia. Resultaten visar att det finns tydliga skillnader mellan nord och sydsluttningarna vid båda platser. Den sida som vetter mot ekvatorn har lägre sluttningsvinkel, är varmare och har mer varierande vegetation. Temperaturutveckling vid ökande höjd över havet undersöktes statistiskt där resultaten inte påvisade någon signifikant korrelation mellan ökande höjd och lägre temperatur vid alla områden utom en. Denna plats, Sani Pass nordliga sluttning, påvisades en statistiskt signifikant sänkning av temperaturen med stigande elevation. Den huvudsakliga slutsatsen som utgår från studien är den att utvecklingen av dalgångsassymetri vid båda platserna är kontrollerad av den ökade intensiteten av de nedslitande processerna på den sida som vetter mot ekvatorn. Detta sker på grund av den större mängd solenergi som denna sida mottar. Interna feedback processer verkar även vara kopplade till skapandet av dalgångsasymmetri. Den största motgången i denna studie är att inte nog med data har samlats samt att vissa viktiga parametrar som jorddjup inte kunnat studeras. Mer forskning behövs inom vegetations roll i interaktionen med fysiska processer på bergssluttningar. Om vegetation intensifierar eller motverkar dessa geomorfiska processer är inte tillräckligt förstått.

The increase in the number of financial restatements in recent years has resulted in a significant decrease in the amount of market capitalization for restated companies. Prior literature does not differentiate between single and multiple restatements announcements. This research investigates the inter-relationships among multiple financial restatements, corporate governance, market microstructure and the firm's rate of return in the form of three essays by differentiating between single and multiple restatement announcement companies. First essay examines the stock performance of companies announcing the financial restatement multiple times. The postulation is that prior research overestimates the abnormal return by not separating single restatement companies from multiple restatement companies. This study investigates how market penalizes the companies that announce restatement more than once. Differentiating the restatement announcement data based on number of restatement announcements, the results support for non persistence hypothesis that the market has no memory and negative abnormal returns obtained after each of the restatement announcements are completely random. Second essay examines the multiple restatement announcements and its perceived resultant information asymmetry around the announcement day. This study examines the pattern of information asymmetry for these announcements in terms of whether the bid-ask spread widens around the announcement day. The empirical analysis supports the hypotheses that the spread does widen not only around the first restatement announcement day but around every subsequent announcement days as well. The third essay empirically examines the financial and corporate governance characteristics of single and multiple restatement announcements companies. The analysis shows that corporate governance variables influence the occurrence of multiple restatement announcements and can distinguish multiple restatements announcement companies from single restatement announcement companies.

The plasma membrane (PM) of live cells has a striking phospholipid asymmetry between bilayer leaflets, yet the purpose of this fundamental structure remains elusive. It is also unknown whether and how this phospholipid asymmetry impacts on the lateral organization of the PM, such as microdomains or lipid rafts that are thought to facilitate specific protein-protein interactions. Here, we generated asymmetric giant unilamellar vesicles (GUVs) and found that microdomain formation is inhibited by outer leaflet very long acyl chain (24:0) sphingomyelin (SM), the primary sphingolipid species in mammalian cells. Interestingly, although cholesterol is believed to associate favourably with SM, molecular dynamic (MD) simulations of asymmetric membranes indicate a strong preference for cholesterol in the inner leaflet when 24:0 SM is in the outer leaflet, as well as, interdigitation of 24:0 SM acyl chain across the centre of the bilayer. We thus hypothesized that the outer leaflet-localized 24:0 SM interdigitates across the leaflets of the bilayer and facilitates cholesterol enrichment in the inner leaflet. Indeed, we obtained evidence that, in asymmetric unilamellar vesicles with 24:0 SM exclusively in the outer leaflet, 75-80% of cholesterol was partitioned into the inner leaflet, which was correlated with the disappearance of microdomains in GUVs. Importantly, in live cell PM, where 24:0 sphingolipids are the predominant species and exclusively in the outer leaflet, cholesterol was similarly enriched in the cytoplasmic leaflet. SM with shorter acyl chains such as 16:0, a minor species in mammalian cells, failed to generate cholesterol asymmetry and promoted microdomains in both symmetric and asymmetric GUVs. Furthermore, we generated live mammalian cells with either 16:0 or 24:0 SM and analyzed submicron domains in these cells, using density-dependent FRET of GPI-anchored proteins. Indeed, 16:0 SM cells are capable of forming submicron domains. The 24:0 SM cells, by contrast, are nearly devoid of submicron domains, as are unmodified control cells. Moreover, we silenced ceramide synthase 2 (CerS2), the enzyme that generates very long acyl chain sphingolipids. We found that silencing CerS2 alters diffusional properties of membrane proteins, consistent with enhanced microdomain formation. Together, our results establish a surprising and central role of very long acyl chain sphingolipids in regulating membrane lateral organization, including in the native plasma membrane, by creating cholesterol asymmetry. We propose that sphingolipid asymmetry functions to dynamically regulate microdomains in live cells.

Functional magnetic resonance imaging studies have long demonstrated a high degree of correlated activity between the left and right hemispheres of the brain. Interregional correlations between the time series of each brain voxel or region and its homotopic pair have recently been identified by methods such as homotopic resting-state functional connectivity (H-RSFC). However, little is known about whether interhemispheric regions in patients with Attention-deficit/hyperactivity disorder (ADHD) are functionally abnormal. The aim of this thesis is to examine the association between H-RSFC and medication status, age, sex, and volumetric asymmetry index (AI). In our approach, region-based activity was obtained using three different methods. To test for associations, two linear mixed-effects models were used. Across results, H-RSFC variation was found in subcortical regions and portions of cortical regions. In addition, changes in functional connectivity were found to be linked with structural asymmetry in two cortical regions. More importantly, shifting in homotopic functional activation was found as a result of medication intake in youths with ADHD. These findings demonstrate the utility of homotopic resting-state functional connectivity for measuring differences among pharmacotherapy intake, gender, neurodevelopment, and structural asymmetry.

Research has shown that lower limb asymmetries can negatively impact performance and risk of injury. However, there is little research on the effects of lower limb asymmetry on running performance, nor the effects of strength training on lower limb asymmetry in runners. The purpose of this study was to examine the relationship between jumping ability and asymmetry and long distance running performance, as well as to determine the performance effects a strength training program has on collegiate runners. Data from athlete monitoring of 10 collegiate distance runners and 6 sprinters were analyzed. Athletes (Distance Runners n = 10, Sprinters n = 6) performed static and countermovement jumps at two testing sessions separated by 21 weeks, during which, they participated in a block-periodized strength training program. The athletes were capable of maintaining a minimal amount of kinetic asymmetry during the jump tests and there were no statistically significant correlations between jump height, jump asymmetry, and cross-country race times. After the strength training intervention, the female distance runners significantly improved static jump height (p value = 0.045), countermovement jump height (p value = 0.015), countermovement jump asymmetry percentage (p value = 0.006), and body fat percentage (p value = 0.002). Although there were no other statistically significant changes, there were promising trends in many of the performance variables. These results indicate that there are potential benefits associated with strength training, and coaches should incorporate it into the overall programming for collegiate runners for injury prevention and enhanced performance.

The contribution of the gluon helicity to the spin of the proton is being studied through the use of the unique capability of the Relativistic Heavy-Ion Collider (RHIC) to collide polarized protons at √s = 200 GeV and √s = 510 GeV. The kinematic coverage of the Solenoidal Tracker At RHIC (STAR) allows access to gluons through quark-gluon and gluon-gluon scattering processes which dominate jet production at low and medium transverse momentum. The polarized gluon distribution function, ∆g(x), can be constrained through a global analysis by measuring the longitudinal double-spin asymmetry (ALL) of inclusive jet and dijet production. Published inclusive jet results from 2009 at mid-rapidity (|η|< 1) at √s = 200 GeV have been used in global analyses and suggest a statistically significant non-zero truncated first moment of ∆g(x) for x > 0.05. An additional data sample with an integrated luminosity of 43 pb−1 has been collected in 2015, which is over twice as large as the corresponding 20 pb−1 of the 2009 data. Longitudinal double-spin asymmetry results from this new large data sample will further improve the precision of ∆g(x) for x > 0.05. / Physics

This thesis reports on two experiments conducted by the HAPPEx (Hall A Proton Parity Experiment) collaboration at the Thomas Jefferson National Accelerator Facility. For both, the weak neutral current interaction (WNC, mediated by the Z0 boson) is used to probe novel properties of hadronic targets. The WNC interaction amplitude is extracted by measuring the parity-violating asymmetry in the elastic scattering of longitudinally polarized electrons off unpolarized target hadrons. HAPPEx-III, conducted in the Fall of 2009, used a liquid hydrogen target at a momentum transfer of Q2 = 0.62 GeV2. The measured asymmetry was used to set new constraints on the contribution of strange quark form factors (GsE,M to the nucleon electromagnetic form factors. A value of APV = -23.803 +- 0.778 (stat) +- 0.359 (syst) ppm resulted in GEs + 0.517 GMs = 0.003 +- 0.010 (stat) +- 0.004 (syst) +- 0.009 (FF). PREx, conducted in the Spring of 2010, used a polarized electron beam on a 208Pb target at a momentum transfer of Q2 = 0.009 GeV2. This parity-violating asymmetry can be used to obtain a clean measurement of the root-mean-square radius of the neutrons in the 208Pb nucleus. The Z0 boson couples mainly to neutrons; the neutron weak charge is much larger than that of the proton. The value of this asymmetry is at the sub-ppm level and has a projected experimental fractional precision of 3%. We will describe the accelerator setup used to set controls on helicity-correlated beam asymmetries and the analysis methods for finding the raw asymmetry for HAPPEx-III. We will also discuss in some detail the preparations to meet the experimental challenges associated with measuring such a small asymmetry with the degree of precision required for PREx.

Antisymmetry is a striking, yet puzzling form of biological asymmetry. The livebearing fish Xenophallus umbratilis exhibits antisymmetry in the male intromittent organ and provides a system that is well-suited for studying the nature of variation in antisymmetrical traits. Using geometric morphometrics, I test the hypothesis that because the gonopodium is critical to fitness there will not be significant differences in gonopodium shape between the two gonopodial morphs in this species. My results are consistent with this prediction, though I found that gonopodium shape did differ with gonopodium size.