Archaeological investigations at a Mississippian platform mound site in Lowndes County, Mississippi

The Upper Tombigbee River Valley and the Black Prairie two adjacent physiographic regions located in northeast Mississippi are defined archaeologically by the existence of multiple single-mound sites with associated farmsteads or small habitation sites. This thesis is an analysis of mound-construction data and the ceramic assemblage excavated in 2017 from the Butler Mound Site (22LO500) a single-mound site located in Lowndes County Mississippi. The purpose of this thesis is to determine when construction of the Butler Mound occurred using mound-construction data ceramic analysis and radiocarbon dating. This thesis also seeks to understand how Butler and neighboring sites relate to one another spatially and temporally to further define Mississippian settlement patterning in northeast Mississippi and to contribute to the developing regional culture-chronology

Phylogenetic Systematics of the Ulvophyceae (Chlorophyta) Based on Cladistic Analyses of Ribosomal RNA Genes and Morphology.

Cladistic analyses of non-molecular and nuclear-encoded rRNA sequence data provided the basis for hypotheses of relationships for the green algal class Ulvophyceae. Non-molecular data rooted with Chara support hypotheses which group the Chlorophyceae and Pleurastrophyceae with ulotrichalean and ulvalean Ulvophyceae. Analyses of rRNA sequence data group the siphonous and siphonocladous Ulvophyceae (i.e. Caulerpales, Siphonocladales, and Dasycladales) with the Chlorophyceae and Pleurastrophyceae. Although hypotheses supported by these independent data sets are incongruent, they suggest that the Ulvophyceae is not monophyletic. Based on rRNA sequences, pleurastrophycean taxa, which, like the Ulvophyceae, possess a counter-clockwise arrangement of flagellar basal bodies, are more closely related to the Chlorophyceae (which possess clockwise basal bodies) than to the Ulvophyceae. Thus, counter-clockwise basal body orientation does not diagnose a monophyletic group. Parsimony analyses to assess the strength of these hypotheses, including bootstrap, decay index, and character distributions suggest that basal divergences exhibit little character support and lead to ambiguous rooting of the phylogeny. Data randomization tests, however, clearly suggest that there is considerable signal in the data. Examination of ordinal relationships within the siphonous and siphonocladous Ulvophyceae revealed that the Dasycladales is the sister group to the Caulerpales with the Siphonocladales representing a basal lineage. Although inconsistent with hypotheses based on ultrastructural features, this hypothesis is consistent with recently reported fossil evidence that extended the minimum age of the siphonocladalean lineage to ca. 700 million years (concurrent with the oldest dasycladalean fossils). Relative rates of evolutionary divergence between sister taxa (inferred by comparing the number of nucleotide changes along internodes leading to terminal taxa) are higher in the Caulerpales and Dasycladales clade than in the Siphonocladales. Congruence of phylogenetic hypotheses with biogeographic distributions were also explored. Two lineages are identified in the Caulerpales; one with genera of strictly tropical distribution and another with more widespread taxa. The sister group, the Dasycladales, is also restricted to the tropics, suggesting that this is the primitive distribution pattern. The Siphonocladales exhibit a similar pattern: derived cosmopolitan clade and basal tropical genera. Thus, these data support the hypothesis that these algae originated in ancient tropical oceans

Strategies for applying active seismic subglacial till characterization methods to valley glaciers

Thesis (M.S.) University of Alaska Fairbanks, 2017Subglacial materials play an important role in glacier dynamics. High pore-pressure, high porosity (dilatant) tills can contribute to high basal motion rates by deforming. Amplitude Variation with Angle (AVA) analysis of seismic reflection data uses the relationship between basal reflectivity and reflection incidence angle to characterize the subglacial material. This technique can distinguish between dilatant tills and less-porous, non-deforming (dewatered) tills due to their distinctive reflectivity curves. However, noise from crevasses and glacier geometry effects can complicate reflectivity calculations, which require a source amplitude derived from the bed reflection multiple. We use a forward model to produce synthetic seismic records, including datasets with and without visible bed reflection multiples. The synthetic data are used to test source amplitude inversion and crossing angle analysis, which are amplitude analysis techniques that do not require absolute reflectivity calculations. We and that these alternative methods can distinguish subglacial till types, as long as reflections from crevasses do not obscure the bed reflection. The forward model can be used as a planning tool for seismic surveys on glaciers, as it can predict AVA success or failure based on crevasse geometries from remote sensing data and glacier bed geometry from radar or from a worst-case-scenario assumption of glacier bed shape. Applying lessons from the forward model, we perform AVA on a seismic dataset collected from Taku Glacier in Southeast Alaska in March 2016. Taku Glacier is a valley glacier thought to overlay thick sediment deposits. It has been the subject of numerous studies focusing on its ice-sediment interactions. Our analysis indicates that Taku Glacier overlies unconsolidated tills with porosity values greater than 33 %, though because of uncertainties due to the lack of a bed reflection multiple, it is possible that the tills are not dilatant

Why can’t I trade? Exchange discretion in calling halts

Stock exchanges exercise discretion when calling individual stock trading halts though the decision making behind the halt remains a “mystery” (WSJ, 2018). Between 2012 and 2015 halts are associated with large price movements (on-average 11%) and occur frequently with 97% of trading days having five or more halts. Given their importance, we investigate how exchanges use this discretion and whether the use of discretion alters the effectiveness of the halts. Our findings suggest halts reflect the preferences of exchange constituents as opposed to simply the stated objectives of the exchanges (i.e., minimizing excess volatility and trades at off-equilibrium prices). Specifically, we find halts are less likely for (i) good news than bad, (ii) firms with opportunistic CEO traders, and (iii) firms with low short interests. We also find some evidence that CEO characteristics are associated with halt outcomes. Concerning halt effectiveness, we find the level of unexplained halt discretion is positively associated with both small halt returns and larger post-halt stock return reversals, suggesting halts with more discretion are less effective

Decision-Making Frameworks For Using Sensor Data And Evolutionary Algorithms To Flush A Contaminated Water Distribution System

In the event that a contaminant enters a water distribution system, opening hydrants to flush contaminated water can protect consumers from becoming exposed. Strategies for operating hydrants can be developed to specify the selection of hydrants and the timing of operations to maximize the amount of contaminant that is removed from the system. As an event unfolds, however, sensor data may be the only information that is available to indicate the location and timing of the contaminant source, and ultimately, hydrant strategies must be selected in a highly uncertain environment. The decision-making framework for making real-time decisions to select hydrant strategies relies on computational and sensor technologies, including the accuracy and precision of sensor data; the timeliness of data availability (e.g., streaming data or data that is collected manually); and computational capabilities to execute search simulation-optimization frameworks in real-time. This research will explore and compare two decision-making frameworks. The first framework integrates real-time algorithms to identify potential source locations and develop hydrant strategies, using precise water quality data and high performance computation. The source identification problem is solved using a multi-population evolution strategies approach, and a genetic algorithm approach is applied to identify hydrant strategies for specified source locations. The second decision-making framework provides a library of response options that can be selected based on sensor data as an event unfolds. The library of hydrant strategies is developed a priori using a simulation-optimization framework. Potential sources are classified based on the order of sensors that are activated, and hydrant strategies are identified to maximize average performance for events within each class through the application of a genetic algorithm framework. The two decision-making frameworks are applied and compared for a set of events that are simulated for a virtual city, Mesopolis

Executive Overconfidence and the Slippery Slope to Financial Misreporting

A detailed analysis of 49 firms subject to AAERs suggests that approximately one-quarter of the misstatements meet the legal standards of intent. In the remaining three quarters, the initial misstatement reflects an optimistic bias that is not necessarily intentional. Because of the bias, however, in subsequent periods these firms are more likely to be in a position in which they are compelled to intentionally misstate earnings. Overconfident executives are more likely to exhibit an optimistic bias and thus are more likely to start down a slippery slope of growing intentional misstatements. Evidence from a high-tech sample and a larger and more general sample support the overconfidence explanation for this path to misstatements and AAERs

A Complex Adaptive Systems Approach To Simulate Interactions Among Water Resources, Decision-Makers, And Consumers And Assess Urban Water Sustainability

The balance between water supply and demand for urban water resources is threatened by population growth, land use changes, and climate change. Interactions among environmental resources, infrastructure, societal norms, and management decisions create complexity and increase the unpredictability of the dynamics of water availability. This research develops a sociotechnical framework to simulate interactions among technical and social systems and assess urban water sustainability. An agent-based model (ABM) is implemented to simulate a community of heterogeneous households as agents. The ABM is coupled with a hydrological watershed model, a water reservoir model, and climate change projections. The increase in the number of household agents, dynamics of consumer demands for landscaping, and enactments of drought restrictions are simulated to assess the depletion of water in the reservoir. Population change projections are used to simulate the increase of households over a long-term planning horizon. Household water demands are simulated using residential end use models to calculate withdraws from a surface water reservoir. Utility manager agents respond to reservoir depletion to enact drought response plans and water use restrictions. Household agents respond to water use restrictions by limiting outdoor water use and to water rebate programs to retrofit water appliances. The ABM framework is applied to Raleigh, NC, which is a rapidly urbanizing area. Falls Lake Reservoir is the major water source for Raleigh, and the ABM framework is validated using historic data describing reservoir levels, withdraws, and releases. Future scenarios are explored to assess the effects of climate change and the effectiveness of policies. Results of the study facilitate insight about the influence of the dynamics of water supply and demands on urban water sustainability