http://hdl.handle.net/2027.42/39366 Search the Channel search http://deepblue.lib.umich.edu/simple-search http://hdl.handle.net/2027.42/60886 Title: Neural and Psychological Mechanisms of Interference Control. <br/> <br/>Authors: Nee, Derek Evan <br/> <br/>Abstract: Interference control is the ability to select relevant information while filtering out irrelevant distracting information. Theories of interference control differ regarding whether a single system of control acts upon multiple representations, or whether dissociable forms of control exist. Moreover, it is unclear whether control relies on the facilitation of relevant information, inhibition of irrelevant information, or both. Here, we combine cognitive psychology, functional neuromaging, and meta-analytic techniques to examine the neural and psychological mechanisms of interference control. We find common control-related activation in the dorsolateral prefrontal cortex across perceptual, memorial, and response selection. However, control networks in more posterior regions of the brain differentiate by the kinds of representations that control acts upon. We suggest that the frontal eye fields and superior parietal lobule may be most closely linked to selective attention mechanisms that underlie perceptual selection, but that these regions may also be recruited to select upon competing memorial and response representations. Interference control processes acting upon competing memories preferentially recruit left ventrolateral prefrontal cortex, which shows enhanced functional connectivity with the medial temporal lobe when selection demands are increased. Finally, response selection processes may engage the premotor cortex, and all forms of selection may be dissociable from inhibition processes that act just before motor execution. We demonstrate that at least in the perceptual domain, control processes act by a combination of facilitation of relevant information and inhibition of irrelevant information, and that inhibition can affect processing at least several seconds into the future. The role of inhibition in memory remains less clear. Our results suggest that common goal-related information stored in the dorsolateral prefrontal cortex biases processing in dissociable posterior networks responsible for different kinds of information. Hence, both common and dissociable neural and psychological mechanisms underlie interference control. http://hdl.handle.net/2027.42/60885 Title: Stability of Cohesive Sediments Subject to Pore Water and Gas Ebullition Fluxes and Effectiveness of Sand and Aquablok Caps in Reducing the Resuspension Rates. <br/> <br/>Authors: Cakir Kavcar, Pinar <br/> <br/>Abstract: This study investigated resuspension of contaminated cohesive sediments subject to pore water flow and/or microbially generated gas release which may potentially enhance resuspension relative to flow generated shear stresses alone. In addition, the effectiveness of capping to control resuspension was examined. The caps considered were sand and clay (AquaBlok®) caps. The laboratory experiments were conducted in a flume with a 2 m test bed constructed of either capped or uncapped sediments that were collected from the Anacostia River pilot study site in Washington DC. Ebullition and seepage processes were simulated with air and water injection into the test bed. Suspended sediment concentrations were measured using a turbidimeter. Due to conflicting conclusions in the literature, an investigation on the stability of non-cohesive sediments (representative of sand caps) subject to injection (discharge from the bed) or suction (flow into the bed). A methodology was developed to estimate the bed shear stress from local Reynolds stress measurements to avoid difficulties in estimating shear stress by more conventional methods. A modification to the well-known Shields relations for initiation of motion was proposed to account for the effect of the seepage. When the data are presented in terms of the modified dimensionless shear stress that incorporates the effect of bed seepage, the results are consistent with the Shields curve. Experiments on cohesive sediments required the development of the entire experimental protocol; air and water flow through the sediment bed was observed to occur through discrete channels. Resuspension rates were quantified in relation to the applied shear stress and pore water or gas fluxes; both effects were shown to increase resuspension compared to baseline experiments with only applied shear stress.Additional measurements were performed with the selected caps to determine their effectiveness in reducing resuspension. The sand cap performed very well in filtering the cohesive sediment that otherwise would be resuspended. The AquaBlok® cap was determined to be highly stable under advective flow induced shear stress. However, it was observed that pressure head build-up beneath the cap either due to gas or water flux on the order of 25 cm results in cap failure. http://hdl.handle.net/2027.42/60884 Title: Dancing and Being: Timba Music, Contested Spaces, and the Performance of Identity in Cuba. <br/> <br/>Authors: Vaughan, Umi A. <br/> <br/>Abstract: It makes sense to study Cuban culture through music because in Cuba music is everywhere, as elemental as water and air. The Cuban musical form called timba is interesting to examine because of the moment of its birth, development and boom, a time of transformation and social crisis in which the Cuban phrase “seguimos en combate” (we are still at war) is particularly poignant, as well as because of the complex system of social relations that exists around the music. Along with the typical characteristics of Cuban son, timba has combined new sounds, instruments, new sections in the classic son format of introduction-body-montuno and, perhaps most significantly, has assumed a different attitude in conceiving and performing popular dance music. I contend that timba was born as a maroon music in the face of challenges posed by a radically changing Cuban society in crisis throughout the decade of the 1990s, in which it has been necessary for certain Cubans¬¬blacks and mulatos especially––to reaffirm their identity, presence, and importance in their own terms inside the culture and social structure of Cuba. The aggressive sounds, marginal themes, vulgar, coded lyrics and the at times eccentric or “ghetto” self representations are but affirmations of identity that intend not to destroy Cuban society but rather to find a just position within it, as has been the case for blacks and mulatos in Cuba since colonial times. Dancing and being––creating, dancing timba music as well as performing the self according to specific strategies in various spaces––Afrocubans extend an historical identity into the future which is in dialogue and tension with wider Cuban society. http://hdl.handle.net/2027.42/60883 Title: Theoderic, the Goths, and the Restoration of the Roman Empire. <br/> <br/>Authors: Arnold, Jonathan J. <br/> <br/>Abstract: This dissertation places “Ostrogothic Italy,” conventionally seen as a “barbarian” successor state in the West, firmly within the continuum of Roman history. It investigates conceptions of Romanness and the impact of Rome’s imperial and cultural legacy during the late fifth and early sixth centuries, telling how a number of Italo-Roman elites were able to fit Theoderic and his Goths into an understanding of a revived and reinvigorated western Roman Empire. It demonstrates that for these individuals, men like Cassiodorus Senator and Magnus Felix Ennodius, Italy remained the western Roman Empire, despite the events of 476, and that Theoderic and his Goths, once qualifying as “barbarians,” played fundamental roles in the perpetuation of Italy’s Roman and imperial identity. These Italo-Romans believed that, until the arrival of the Ostrogoths, the western Empire had languished in a state of political and cultural decline, but that both Theoderic and his Goths had provided the necessary remedies. In the Goths Italo-Romans received valiant soldiers who once more defended the Empire against real “barbarians” and even reclaimed lost provinces in the name of Rome. By obeying and upholding Roman law, moreover, these Goths were imagined to have become tolerably Roman and, as such, could actually re-Romanize lapsing Italo-Romans and newly reclaimed provincials, such as the inhabitants of Gaul. In Theoderic Italo-Romans received the kind of emperor that they wanted, a princeps who lived up to the ideals of the Principate, looked and acted like an emperor, and restored Rome’s rightful place as the head of the world. Theoderic’s Roman upbringing in Constantinople, east-Roman career, and noble ancestry rendered him an acceptable and welcomed candidate to the imperial purple. More importantly, the positive alterations witnessed during his reign, such as the renovation of declining cities and reassertion of Roman dominance in the West, affirmed that he was a good Roman emperor. It was for these reasons, this dissertation suggests, that Italo-Romans were hailing the restoration of the western Roman Empire and declaring that a golden age had dawned.