A persistent unanswered question in cognitive neuroscience has been what are the neural origins of human brain lateralization? Language is strongly lateralized to the left-hemisphere, however, lateralization varies with language experience. Bilinguals demonstrate a greater extent and variability of right-hemisphere involvement for language relative to monolinguals. Here, bilingualism is used as a lens into the conditions that drive brain lateralization. Why does bilingual language processing yields more robust bilateral neural activation relative to monolingual language processing? Neural activation and functional connectivity were measured to test hypotheses about the temporal dynamics of hemispheric recruitment during language processing in monolingual and bilingual children with varying ages of first bilingual language exposure. Hypothesis (1), The human brain is strongly left-hemisphere lateralized for language, but, when faced with the demands of two languages, additional right-hemisphere resources are recruited. Hypothesis (2), The human brain has the potential for enhanced dual hemispheric language processing that can be either potentiated or not based on early life bilingual versus monolingual language experience. If dual language experience places increased cognitive demands on the bilingual brain requiring additional right-hemisphere resources, asynchronous neural activation in left and right hemispheres was predicted. If dual language experience potentiates dual hemispheric language processing, synchronous neural activation in left and right hemispheres was predicted. Furthermore, only early-exposed bilinguals but not later-exposed bilinguals or monolinguals, would show synchronous neural activation across the hemispheres. Early experience with one language (monolinguals) or two languages at different times during a child's development (early-exposed bilinguals, later-exposed bilinguals) revealed differences in the time-course of activation across the two hemispheres' language areas, supporting Hypothesis (2). Monolinguals and later-exposed bilinguals showed asynchronous activation between the hemispheres. Early-exposed bilinguals showed synchronous activation between the hemispheres. The results provide a new view on how different experiences can drive lateralization in development and reveal the neural basis of bilateral activation in the bilingual brain. Synchronous temporal accessing of the hemispheres in bilinguals suggests early life bilingual language experience may support more equal and efficient hemispheric involvement, and, in turn, constitute the brain-based mechanism that makes possible the widely observed linguistic and cognitive advantages in young bilinguals.

Introduction: A common disorder arising most frequently after a left hemisphere stroke is limb apraxia. Limb apraxia is a deficit of skilled movement, such as performance of activities of daily living (ADLs), that is not a result of primary motor or sensory impairments, or deficits in motivation, memory, or comprehension (De Renzi, 1990). Currently, clinical neuropsychological assessment of apraxia relies largely on qualitative analyses of gross movements during the performance of activities of daily living in two task conditions (pantomime and tool). Further, apraxic patients often perform ADLs with their non-dominant limb to avoid often-present right-hand hemiparesis, but the assessment does not adequately account for this. Thus, it is unclear whether movement deficits are due to non-dominant limb use or limb apraxia. Moreover, it is not known how different task conditions and aging influence the performance of ADLs in healthy populations, as well as manual asymmetries. Purpose: The purpose of this thesis was to: 1. determine if age affects the magnitude of manual asymmetry in the performance of two ADLs (drinking water from a cup and slicing a loaf of bread with a knife); 2. determine if different task demands (pantomime and tool condition) affect magnitude of manual asymmetries during the performance of ADLs; and 3. determine if aging affects how task demands are expressed during the performance of ADLs. Methods: Fifty healthy right-hand dominant (as determined via Waterloo Handedness Questionnaire) younger and older adults participated in this study. A grooved pegboard task was completed by all participants prior to performance of the two ADLs using motion tracking. Upper limb movements (dominant and non-dominant limb) were captured at 60 Hz via a motion capture system (Vicon, Oxford, UK). Participants performed two task conditions: 1) pantomime (pretending to perform an ADL without holding the tool); and 2) tool (pretending to perform an ADL while holding the tool) in two ADLs: drinking water from a cup and slicing a loaf of bread with a knife. Each ADL was performed six times by both limbs. ADLs and limbs were randomized, while task conditions were blocked randomized between participants. Results: Overall, this study found that aging slows down motor performance on the Grooved Pegboard task, as well as the performance of both ADLs. Manual asymmetries were task dependent. The cup and knife ADL were both characterized by larger manual asymmetries in older adults relative to the younger adult group, particularly in terms of angular movement. Further, it was found that task demands were expressed differently in older adults relative to younger adults, with the tool condition yielding performance improvements in both groups. Conclusions: Despite the previous research, which has shown that manual asymmetries are reduced in older adults during the performance of motor tasks, this investigation points to the opposite during the performance of activities of daily living. Aging appears to increase the degree to which manual asymmetries are expressed. Further, aging also appears to play a role in the change in temporal and angular aspects of movement during the performance of ADLs in different task conditions. The degree to which task demands as reflected in the two task conditions improve or impair performance in healthy populations should be taken into consideration when evaluating ADL performance in patients with limb apraxia. In accordance with the previous research on aging, this study has shown that upper limb movements become slower as individuals age. Kinematic relationships presented in this study provide researchers and clinicians with an insight into how manual asymmetries, aging and different task demands come into play during the performance of one cyclical and non-cyclical task.

A persistent unanswered question in cognitive neuroscience has been what are the neural origins of human brain lateralization? Language is strongly lateralized to the left-hemisphere, however, lateralization varies with language experience. Bilinguals demonstrate a greater extent and variability of right-hemisphere involvement for language relative to monolinguals. Here, bilingualism is used as a lens into the conditions that drive brain lateralization. Why does bilingual language processing yields more robust bilateral neural activation relative to monolingual language processing? Neural activation and functional connectivity were measured to test hypotheses about the temporal dynamics of hemispheric recruitment during language processing in monolingual and bilingual children with varying ages of first bilingual language exposure. Hypothesis (1), The human brain is strongly left-hemisphere lateralized for language, but, when faced with the demands of two languages, additional right-hemisphere resources are recruited. Hypothesis (2), The human brain has the potential for enhanced dual hemispheric language processing that can be either potentiated or not based on early life bilingual versus monolingual language experience. If dual language experience places increased cognitive demands on the bilingual brain requiring additional right-hemisphere resources, asynchronous neural activation in left and right hemispheres was predicted. If dual language experience potentiates dual hemispheric language processing, synchronous neural activation in left and right hemispheres was predicted. Furthermore, only early-exposed bilinguals but not later-exposed bilinguals or monolinguals, would show synchronous neural activation across the hemispheres. Early experience with one language (monolinguals) or two languages at different times during a child's development (early-exposed bilinguals, later-exposed bilinguals) revealed differences in the time-course of activation across the two hemispheres' language areas, supporting Hypothesis (2). Monolinguals and later-exposed bilinguals showed asynchronous activation between the hemispheres. Early-exposed bilinguals showed synchronous activation between the hemispheres. The results provide a new view on how different experiences can drive lateralization in development and reveal the neural basis of bilateral activation in the bilingual brain. Synchronous temporal accessing of the hemispheres in bilinguals suggests early life bilingual language experience may support more equal and efficient hemispheric involvement, and, in turn, constitute the brain-based mechanism that makes possible the widely observed linguistic and cognitive advantages in young bilinguals.

Thesis (M.S.)--University of Michigan, 1938.

This experiment was based upon earlier research involving beginning musicians' perception of how handedness interferes with their performance of melodic instruments, (VanAlstine, 2006) and the analysis of earlier studies by Laeng and Park (1999) involving the impact of handedness in playing the piano traditionally and in a "reversed" fashion. This study was conducted involving the performance of musical examples on the recorder where the subjects played in a traditional manner, as well as with reversed hand position. Laeng and Park found left-handed beginning and experienced musician's grouped subjects performed better upon a reversed keyboard than performing upon a traditional keyboard, Laeng and Park (1999). VanAlstine hypothesized that beginning musicians would play more correct notes with their dominant hand when playing the melodic examples, whereas advanced students would show less specialization when performing the musical examples with either hand. There were 60 subjects total, 30 beginning players from Carterville Intermediate School and 30 advanced players from the southern Illinois area, including the Southern Illinois University Carbondale School of Music. Subjects were given an Edinburgh-styled handedness test to identify them as either left- or right-handed performers. The subjects were further divided into groups of 15 beginning left-handed players, 15 beginning right-handed players, 15 advanced left-handed players and 15 advanced right-handed players. Subjects played short musical examples on the recorder with traditional fingering and then with reversed hands. The performance was evaluated by two judges. Beginning right-handed musicians who performed upon the "reversed" recorder played as well as performers who were left-handed and played the soprano recorder traditionally, with their dominant hand on the top half of the instrument. The left- and right- handed advanced musicians played the musical examples equally well in both the traditional style and in the "reversed style."

Thesis (MSD) --Boston University, Henry M. Goldman School of Dental Medicine, 2015 (Department of Orthodontics and Dentofacial Orthopedics). / Includes bibliographic references: leaves 43-50. / Background: Mirror imaging in identical twins has long been noted and suggests that left-right asymmetry may become established early in embryogenesis. However, it is not known whether the clinical reports of “mirroring” in twins are annulled by an equal number of cases lacking mirroring. As left-right patterning is a key component of laterality-based birth defects, it is important to determine whether aspects of left-right asymmetry are in fact set prior to the splitting event that produces monozygotic twins. We aimed to determine whether significant mirror imaging occurs in transverse facial asymmetries in monozygotic and dizygotic twins. Material and Methods: The sample included PA cephalograns from 56 pairs of monozygotic twins and 57 pairs of dizygotic twins from the Forysth/Moorrees Twin Study (females age 14-1 5 and males age 15-16). The films were digitized and anatomical landmarks identified. Using Geometric Morphometric analyses including Procrustes superimposition, the landmark configuration of one individual twin was reflected (mirrored) and superimposed using Procrustes superimposition. Principal components analysis (PCA) and MANOVA tests 1V were performed to determine the differences between monozygotic and dizygotic twins. A secondary Procrustes superimposition was then conducted without reflection. If mirroring asymmetry was present, the average Procrustes distance within reflected twin sets (D1) would be smaller than those superimposed without reflection (D2). T tests were performed to determine the differences between reflected and non-reflected regions in monozygotic and dizygotic twins. Results: After reflection, no statistically significant differences were found for any regions (with the exception of Mandible A Right, p=0.0258) between monozygotic and dizygotic twins. When comparing reflected versus non-reflected regions, Midface D Left and Mandible C Right in dizygotic twins yielded negative values for D1-D2; however permutation tests revealed these values are not significant. T tests showed 15 out of 20 regions had significant smaller mean values for D2 versus Dl in monozygotic twins, while only 7 out of 20 in dizygotic. A Z test comparing these two proportions revealed this difference between twin types is significant (p=0.011), With the monozygotic twins having significantly more regions that fit better when non-reflected than the dizygotic twins. Conclusion: No statistically significant differences in mirroring were found between monozygotic and dizygotic twins in any craniofacial regions except for Mandible A Right, in which dizygotic twins showed a better fit when mirrored. Upon examination of the differences between reflected and non-reflected regions, monozygotic twins showed a statistically significantly greater number of regions that fit better when superimposed versus reflected in comparison to dizygotic twins. From this study we conclude that no significant mirroring occurs in craniofacial asymmetries, perhaps due to the biological stability of neural crest cells that derive the cranial cartilage and skeleton.

The first essay explores relations between political affiliations and illegal insider trading. Assessing illegal insider trading is challenging due to the nature of the activity. Researchers observe and evaluate only the detected portion of illegal trading, not all illegal transactions. This presents a problem when using traditional empirical techniques to investigate such activity. In our analysis we employ a bivariate probit model that takes into account the partial observability nature of insider trading and provides estimates for the determinants of both the commission and the detection of illegal insider trading. Among our findings, most notable is the influence of the SEC’s political structure on insider trading detection. We show that the political party affiliation within the SEC, past indictments by the SEC, and SEC budget play a crucial role in determining current prosecution. Past SEC indictments significantly decrease the likelihood to engage in illegal insider trading as well. Essay two investigates insider trading returns by corporate insiders in light of their firms’ lobbying activities. Lobbying is a channel firms often use to influence regulatory change. Firms also use lobbying to obtain information on upcoming legislative and regulatory changes that are significant to the firms’ future. Establishing and maintaining these political connections provides informational advantage not only to the firms engaged in lobbying but also to the insiders of these firms who receive an opportunity to base their trading decision on this potentially valuable information. Using data on firm lobbying activities, we provide evidence of an informational advantage acquired by corporate insiders of firms that develop these connections with policymakers. We find that insiders of lobbying firms gain additional return of 138 (156) basis points on their buys (sells) trades relative to transactions placed by insiders of firms that are not engaged in lobbying activities. We also document that the role of establishing and fostering lobbying contacts and the amounts spent on lobbying differ with type of insider transactions and length of investment horizons. The focus of the third essay is the impact of actual trading on material non-public information on firms’ securities. Finance and law scholars present theoretical arguments both in favor of and against trading on material non-public information. However, investigating empirically the actual impact of insider trading on the insider’s firm poses significant challenges due to the lack of precision in identifying from publically available data trades that are based on private information. In this study, we utilize Securities Exchange Commission (SEC) indictments of illegal insider trading to examine the impact of illegal insider trading on the firm. We provide evidence suggesting that illegal insider trading increases stock market liquidity for the involved firms. Our results imply that bid-ask spread following transactions based on private information is narrower for long-run windows. However, we also find results implying that informed trading is associated with reduced liquidity, when estimated with Amihud Illiquidity proxy, reflecting price impact of trades based on private information.

Although complex, inconsistent and fickle, the time-averaged flow over a stationary slender forebody is generally well-understood. However, the nature of unsteady, time-varying flows over slender forebodies - whether due to the natural unsteadiness or forced maneuvering - is not well-understood. This body of work documents three experimental investigations into the unsteadiness of the flow over a 3.5 caliber tangent-ogive cylinder at high angles of incidence. The goal of the investigations is to characterize the natural and forced flow unsteadiness, using a variety of experimental tools. In the first investigation, flow data are collected over a stationary model in a water tunnel. Particle-Image Velocimetry (PIV) is employed to acquire time-dependent planes of velocity data with the model at several angles of attack. It is discovered that the asymmetric flow associated with the tangent-ogive forebody exhibits a large degree of unsteadiness, especially for data planes located far from the forebody tip. Vortex shedding of the type exhibited by a circular cylinder in crossflow is observed, but this shedding is skewed by the presence of the tip, the shedding process does not require equal periods of time from each side of the body, and this results in a time-averaged flowfield that is asymmetric, as expected. The rms values of the time-averaged velocity, as well as the turbulent kinetic energy and axial vorticity are calculated. In the second investigation, surface pressure data are acquired from several circumferential rings of pressure ports located on two models undergoing ramp coning motions in two different wind tunnel facilities. The surface pressure data are integrated to determine the sectional yaw forces. Coning motions were performed at several different reduced frequencies, and pneumatic control actuation from the nose was employed. The chosen control actuation method used a small mass flow rate ejected very close to the forebody tip, so as to leverage the inherent convective instability. The data resulting from these tests were analyzed in order to determine how the coning motions affect the distribution of surface pressure and yaw forces, how quickly the flow reacts to the motion, and the extent of control authority of the pneumatic actuation. It was discovered that the yaw forces increase in the direction of the motion for small reduced frequencies, but in the direction opposite to the motion for large reduced frequencies. The effects of the motion tend to dominate the control method, at least for the reduced frequencies and setup tested in the low-speed wind tunnel. The results from the high-speed testing with transitional separation give a preliminary indication that the control method could have sufficient control authority when the reduced frequencies are low. The third investigation involves tangent-ogive cylinder undergoing a pitching maneuver in a water tunnel. Laser-Doppler Velocimetry (LDV) is used in order to map out several planes of velocity data as the model is pitched. The LDV data is used to calculate vorticity and turbulent kinetic energy. Variables that are proportional to the flow asymmetry and proximity to the steady-state flow are defined. All of these variables are displayed as a function of time and space (where appropriate). The delay in the development of the asymmetry and the flow progression to the steady state are determined to be a function of pitch-axis location. The propagation velocity of the convective asymmetry is faster than expected, most likely because of the increased axial velocity in the vortex cores. Vortex breakdown of one of the vortices is observed, with loss of axial velocity and dilution of the vorticity over a large area. The cause of this phenomenon is not yet understood, but it is reminiscent of vortex breakdown over delta wings. / Ph. D.

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