Search

Ammonia (NH3) is the major alkaline gas in the atmosphere, with around 90 % of the total anthropogenic emissions in Europe coming from agriculture-related sources. Following emission to the atmosphere, the neutralisation reaction between NH3 and the acid gases sulfur dioxide (SO2), nitric acid (HNO3) and hydrochloric acid (HCl) produces secondary inorganic aerosols (ammonium nitrate (NH4NO3), ammonium sulfate ((NH4)2SO4) and ammonium chloride (NH4Cl)). With longer atmospheric lifetimes than the gases, the aerosols also contribute to transboundary pollution problems. The gases and aerosols are removed from the atmosphere by wet (in precipitation) or dry (direct uptake by vegetation and surfaces) deposition processes. Together, they can negatively impact the natural environment through the input of excess acidity and nutrient nitrogen and harm human health through the formation of aerosols that contributes to fine-mode particulate matter (PM2.5). They can also potentially influence climate change from the radiative forcing properties of the aerosols and the inputs of nitrogen that can alter the carbon cycle. Monitoring data are necessary for assessing the spatial and temporal extent of pollution and as evidence to detect changes in pollutant concentrations in response to current and future policies to mitigate emissions of NOx, SO2 and NH3. Combined with models, the concentration data are also used to estimate the different fractions of the total sulfur or nitrogen input and different chemical forms of the pollutants. Since the spatial and temporal patterns and atmospheric behaviours of gases and aerosols differ, measurements therefore need to distinguish between the phases. The development of simple, low-cost, time-integrated air sampling methods and their application in cost-efficient monitoring strategies to assess temporal, spatial and trends in the gas and aerosol pollutants in the UK and across Europe is described. An active diffusion denuder method (DELTA®) and a passive sampler (ALPHA®) are implemented at a large number of sites (> 70) in the UK National Ammonia Monitoring Network (NAMN, established 1996) to measure NH3 with a monthly frequency. An extension of the DELTA® method provided additional, monthly measurements of particulate NH4+ (for the NAMN) and of the acid gases (SO2, HNO3, HCl) and aerosol species (NO3 , SO42-, Cl , Na+, Ca2+, Mg2+) for the UK Acid Gas and Aerosol network (AGANet, established 1999) at a subset of NAMN sites. The close integration of the two networks demonstrated the cost-effectiveness of the DELTA® approach, which provided quality assured, concurrent speciated measurement data on multiple pollutants at multiple sites, and also simplicity of operation by a large network of site operators, some of whom have no technical or scientific background. The DELTA® approach and quality protocol developed in the UK networks was further applied to a pan-European NitroEurope (NEU) DELTA® network (20 countries: 2006 – 2010), with knowledge sharing and collaboration between multiple laboratories and research organisations. Important features in the spatial variability and seasonality in the gas and aerosol components were captured in the UK and European networks. The gases, with shorter lifetimes in the atmosphere were found to be spatially more heterogeneous, with a wider range of concentrations than their aerosol counterparts. Variations on a spatial scale were correlated with distributions and magnitude of emission sources, e.g. NH3 and NH4+ concentrations were highest in intensively farmed areas (e.g. East Anglia in eastern England, NAMN) and countries (e.g. the Netherlands, NEU DELTA®). In the UK, evidence is also presented of the contribution by long-range transboundary sources to enhancement of concentrations of NH4NO3 and (NH4)2SO4.Distinct and contrasting seasonal cycles in the gas and aerosol phase components were established, important for identifying periods of pollution and for targeting abatement measures. The observed variations were attributed to seasonal changes in emission sources, atmospheric interactions and the influence of climate on partitioning between the gases and aerosols. For NH3, peaks in concentrations occur from increased volatilisation promoted by warm, dry conditions (summer) and also from agriculture-related emissions, with a main peak in spring and a smaller peak in autumn. Concentrations of SO2 were higher in winter (increased combustion), except in Southern Europe where the peak period was in summer. HNO3 concentrations were more complex, with small peaks in the seasonal cycle related to traffic and industrial emissions, photochemistry, meteorology and the influence of climate on HNO3:NH4NO3 equilibrium. In comparison, the springtime peak in NH4NO3 was attributed to the reaction of a surplus of NH3 with HNO3 to form NH4NO3 in the aerosol phase under cooler, wetter conditions. A summertime peak in particulate SO42- was observed in Southern Europe, coinciding also with peaks in SO2, NH3 and HNO3 concentrations. While the high HNO3 concentrations suggests increased oxidative capacity for formation of H2SO4 (from SO2) and reaction with NH3 to form (NH4)2SO4, the absence of an NH4+ peak illustrates the larger influence of the more abundant NH4NO3 in controlling the seasonality of particulate NH4+.Important changes in the atmospheric concentrations and partitioning between the different gas and aerosol components were captured. The measurement data highlighted the dominance of NH3 and NH4NO3 in rural air, as the emissions of SO2 and NOx continues to fall, against a backdrop of increasing NH3 emissions in the UK and across Europe since 2013. The observed shift in the form of NH4+ aerosol from the stable (NH4)2SO4 to the semi-volatile NH4NO3 is expected to maintain a larger fraction of the NH3 and HNO3 in the gas phase. NH4NO3 can act as a reservoir and release the gases in warm weather, which may partly explain the observed non-linearity between emissions and measured concentrations of NH3 in the UK data. The current and projected trends in the emissions of the gases SO2, NOx and NH3 suggest that NH3 and NH4NO3 can be expected to continue to dominate the inorganic pollution load over the next decades.

Deltas form where a river meets a standing body of water (e.g. ocean) and deposits its sediment load. They are sensitive recorders of the interplay of fluvial (river) processes, that deliver the sediment to the standing body of water, and wave and tidal processes that redistribute the delivered sediment. When basinal (waves/tides) processes cannot sufficiently redistribute the delivered sediments, river-dominated deltas prevail, which are fantastic recorders of autogenic (internal to the delta) processes that control its overall evolution and internal architecture. Allogenic (external to delta) processes, such as tectonics, can influence and modify the river produced architecture. Therefore, understanding these competing autogenic and allogenic processes is key to creating predictive evolutionary models of river-dominated deltas, and their depositional architecture in the subsurface. This project focuses on a spectacularly well-exposed Early Cretaceous fluvio-deltaic succession of the Maestrazgo Basin in central-eastern Spain. These were deposited in a semiisolated, tectonic rift sub-basin during a rifting cycle from the Upper Jurassic to Middle Cretaceous. The succession displays two regressive phases of shallow-water river-dominated deltas that prograded into a carbonate-dominated shelf during an overall longer term transgression. This project uses a combination of remote sensing and geological fieldwork techniques, and methods of sequence stratigraphy, and architectural element analysis in order to understand the possible autogenic and allogenic processes that controlled the stratigraphy and architecture of the fluvio-deltaic succession. The results show that at the scale of the delta, channel cannibalisation and re-channelisation of the mouth bar top (autogenic process) leads to the creation of mouth bars consisting of multiple smaller-scale sub-bars, which is the first to be reported in ancient river-dominated deltas. At the larger delta depositional scale, the overall evolution displays a combination of eustatic, tectonic, and sediment supply allogenic controls, influencing stacking patterns, internal architecture and overall evolution. This study advances our scientific understanding of these processes but has applied implications for subsurface reservoir architecture models used by the oil and gas industry.

In this thesis we present the work we have done to further the understanding of neutral pion photoproduction from the proton. Our work used heavy-baryon chiral perturbation theory to fourth order, and we explicitly include the ∆(1232) resonance using the delta power-counting scheme. We also test the effects of including and excluding D-waves, partial waves with orbital angular momentum quantum number of 2. We begin our discussion in chapter 1 with a brief history of nuclear physics before showing how current algebras and the partial-conservation of the axial-vector current (PCAC) can be used to describe low-energy hadronic interactions. To improve upon PCAC results, one can make use of chiral effective field theories, taking advantage of the chiral symmetry that is present in the limit of massless quarks. We formally introduce chiral perturbation theory (χPT) in chapter 2, discussing the power-counting problem that arises once baryons are included, and present two different approaches to overcome this. We conclude chapter 2 showing how the theory can be extended to include the ∆(1232) resonance. In chapter 3 we describe the model-independent framework of pion photoproduction needed to describe both theory and experiment. We discuss the various recent efforts to describe pion photoproduction within χPT in the latter half of chapter 3. We lay out the framework we have developed in chapter 4 and present our results in chapter 5. We have compared our work to the recent experimental data released by the A2 and CB-TAPS collaborations at the Mainz Microtron. Our results show that we can accurately describe the data from threshold up to an in-coming laboratory photon energy of approximately 260 MeV, a clear improvement on previous studies. We find that including the ∆ is necessary to describe the data beyond E γ ≈ 200 MeV, but the case for D-waves is not so clear. We cannot pinpoint an energy where their inclusion is necessary but we do find evidence suggesting they are important to improve the stability of the fit. Our best results require the inclusion of both the ∆ and D-waves. Finally, in chapter 6, we present our concluding remarks from what has been achieved over the last four years of study and what forms possible extensions of our work could take.

This study catalogues and analyses 329 statuettes and amulets from Thonis-Heracleion, a sunken city off the coast of Egypt that flourished between the 7th and 2nd centuries BC. This is the first study of votive statuettes and amulets from the Late and Ptolemaic Periods that presents a comprehensive corpus from a single site, complete with detailed catalogue entries and photographs. Although some of the most exceptional pieces were previously published in an exhibition catalogue, the majority are unpublished and it is the first time they have been studied and viewed as a whole. The material includes not only Egyptian-style bronzes, which are typical dedications of this period, but also a range of other materials including lead, terracotta, faience, and limestone. Some figures are represented in foreign style and attest to a small hellenized community at the site. By viewing multiple categories of votive material laterally and in context, important conclusions about cultural interactions and cult practice at Thonis-Heracleion come to light. Chapter One details the find context of the statuettes and amulets, followed by a discussion of their types and the cults to which they attest in Chapter 2. Chapter 3 outlines the objects’ primary functions and demonstrates the ways that lead and bronze were utilised differently. Chapter 4 focuses on bronze and lead production methods, particularly methods of replicable production that are indicative of technological exchange with other Mediterranean cultures. Finally, in Chapter 5, I look at how the votives reflect the cultural community at Thonis-Heracleion, and how they compare to others at sites throughout Egypt. Each chapter highlights how the archaeological context informs us about cultural interactions between Egyptians and Greeks and about the dynamics of cult practice at a Delta site in the Late and Ptolemaic Periods.

The Notch signalling pathway is universally conserved in all metazoan species, and is involved in many aspects of cell fate determination and tissue homeostasis, during development and in adult organisms. Several developmental diseases are associated with defective Notch signalling, and the Notch pathway has been implicated in a growing number of cancers. The Notch signalling pathway requires direct cell-cell contact for ligand binding and receptor activation to occur. Specific domains within the Notch receptors and ligands have been identified as necessary for the interaction to take place, and a series of enzymes are known to regulate Notch signalling via glycosylation. Other domains beyond the minimal ligand binding region of the Notch receptor are also known to influence binding. The aim of this study was to characterise the molecular basis for ligand binding by the Notch receptor, and how this is regulated by glycosylation. The effects on ligand binding of specific amino acid substitutions and sugar modifications were tested using prokaryotically -expressed proteins, and a series of constructs containing additional domains N-terminal of the ligand binding region was produced prokaryotically and eukaryotically to test how additional domains might affect ligand binding. Binding was assessed by a flow cytometry-based binding assay and by SPR in order to investigate how particular modifications affected ligand binding. These assays indicated that an evolutionarily-conserved hydrophobic site exists within the central β-sheet of EGF12 in the Notch receptor that is directly adjacent to the O-fucosylation site within this domain. The GlcNAc-fucose disaccharide modification at this position was found to increase binding of hNotch1 to both Jagged1 and DLL4. Additional EGF domains N-terminal to the ligand binding region showed opposite effects on binding to these two ligand classes, suggesting that the precise mode of binding may vary slightly between different Notch ligands.

Recent recognition of compound delta clinoforms reveal pillars to understanding delta progradation and uncover a significant misunderstanding in deltaic architecture. Little effort has been dedicated to spatially delineate delta 3-D morphologies at and away the sediment sources and relate these architectures to stratigraphically constrain ancient deposits. Our assessment of over 35 Holocene deltas allowed the consolidation of a robust geospatial qualitative and quantitative analysis where we consistently observe two main gradient breaks at tens of meters water depth that display varying delineated geometries. The resulting geospatial framework reflects relatively steep shoreline and subaqueous clinoforms – reaching up to 0.49 degrees – separated by a gently dipping platform of maximum 0.11 degrees, and variability in geospatial distance relative to the sediment source and basinal energies. As a result, the extracted geospatial frameworks from modern observations facilitate reinterpretation of ancient deposits, where most compound delta clinoform recognition difficulty arises from the lack of facies criteria, especially for the subaqueous delta, and the limited incorporation of modern systems’ insights. We evaluate the Cretaceous Kenilworth Member of the Blackhawk Formation along the Book Cliffs outcrop belt in Utah, and suggest a new compound delta clinoform hypothesis. Outcomes of this study extend to anchoring the understanding of sediment transport in deltas and shallow marine systems and supporting delta numerical models. Concurrently, this study has direct industry implications in expanding hydrocarbon reserves, increasing CO₂ sequestration potential, and improving facies models for reservoir characterization.

Abstract: The Lower Cretaceous Falher Member is an important hydrocarbon reservoir in the Deep Basin of Alberta and British Columbia. Owing to its economic importance, it has been the subject of many studies. However, there remains contention on the depositional interpretation of individual Falher Member conglomerate units. Both shoreface and wave-dominated deltaic models have been proposed. As such, the Falher Member is an ideal outcrop analog that can be used to assess the spatial distribution of component lithofacies and sedimentary features of shoreface and wave-dominated delta deposits. The present research uses sedimentology and ichnology, within the context of 3D photogrammetric models, of several Falher-equivalent outcrop successions on Mount Spieker in northeastern British Columbia. Facies distributions and relationships are assessed through 3D outcrop models and collected field data. The presence of fluid mud lenses, terrestrial fossil fragments, and impoverished suites of trace fossils confirm that the study interval was deposited proximal to a fluvial sediment source. The abundance of HCS sandstone units and pebbly storm lags indicates robust storm-wave reworking at the time of deposition. The along-strike heterogeneity in facies distribution is interpreted as evidence for delta asymmetry. The proposed depositional model suggests that strong longshore currents were the main reason for delta asymmetry. In this wave-dominated deltaic setting, the updrift side presents better reservoir targets including thick, clast-supported conglomerate units. The downdrift side consists of finer grained argillaceous deposits representing poorer reservoir quality. This study documents the sedimentology of the studied outcrops and discusses the depositional processes causing the heterogeneity in facies type and distribution in a wave-dominated, gravel-dominated delta setting.

Insights into transformative coastal processes are unlocked though understanding sediment transport mechanisms in fine-grained delta front environments. Movement of fine-grained sediments on delta fronts is not wholly explained through advection settling models. While advection settling models generally assume deposition into a still body, numerical modeling of sediment re-entrainment suggests there may be tidal, wave, and/or non-steady hydrograph influences allowing particles to reach greater distances by altering the decelerating velocity field. This research explores both an advection settling model and a mass conservation Rouse profile model to understand the irreducible delta front processes controlling sediment deposition. Using field data collected on the Wax Lake Delta, Louisiana, USA, the irreducible processes of a fluvially dominated delta are quantified to understand the influences of riverine and coastal processes.

The distributary channel network morphology on deltas is important for the delta evolution study because channels are the primary conduit for carrying and distributing water, sediment, and nutrients to the coast. Numerical models of river deltas and their channels have improved remarkably over the past two decades. However, the long-term (millennial scale) simulation of real delta systems remains rare. Here, we attempt to reconstruct the Lafourche Delta channel network, active 1600-600 years before present, with a simple numerical model (Moving Boundary Model for Distributary Network, MB_DCN). The model was run for 9 possible paleo basin boundaries and 6 water discharge parameterizations based on the Mississippi River discharge rate. In each case, the model produced distinguishing channel characteristics including a channel network geometry, progradation rate, and number of bifurcation. For the appropriate basin shapes, reasonable water discharge and common sediment transport parameters, MB_DCN produced a channel network that resembles the Lafourche Delta channel network morphology and progradation rates. The sediment transport nonlinearity appears to set the network geometry, the basin boundary constrains channel direction, and water discharge controls channel tip growth rate. The model produces a millennial scale channel evolution on delta, despite its simplicity.

This thesis presents an outcrop-based, near depositional-strike cross section of fluvio-lacustrine interactions along the well-studied Nine Mile Canyon near Helper, Utah, highlighting the strike variability of facies and depositional environments in the Sunnyside Interval fluvio-lacustrine deposits. We utilize a new, high-resolution correlation panel to demonstrate the existence of a new lacustrine sequence stratigraphic concept: the Supply-Generated Sequence (SGS), which allows subdivision of the cyclically deposited alluvial, fluvial, and lacustrine facies in the Sunnyside Interval based on identifiable stratigraphic horizons, indicating periods of marked clastic input followed by subaqueous lake deposition. This novel conceptual framework helps address the inadequacy of previous sequence stratigraphic interpretations of the Sunnyside Interval. Conventional interpretations rely on premises regarding base level and sediment discharge that were developed for marine settings and do not apply directly to lacustrine systems because the creation and preservation of sedimentary deposits must logically occur during base-level rise in lake basins. In marine settings, base-level draw-downs are interpreted as the common causal mechanism for deltaic progradation, leaving sediment supply as a secondary consideration. In lacustrine systems, accommodation and sediment-supply are generated by water and sediment discharge routed through tributary rivers, making pulses of deposition inherently transgressive in nature. Our findings corroborate recent studies that consider the large, channelized sandstone deposits (shown to be accompanied by δ13C negative excursions) of the Sunnyside Interval to be discharge macroforms deposited during orbitally forced high-discharge early Eocene Hyperthermal events that lasted ~40 kyr. We also document the lateral complexity and discontinuity of hyperthermal sandstone event deposits and show the approximate durations of Sunnyside Interval SGSs to be 40-50 kyr, adding further evidence for the hyperthermal forcing mechanism model. We examine four previously proposed analogs of the Sunnyside Interval System, comparing basin type, morphology, lake level change, and depositional slope. We submit that the Neales River Delta in Lake Eyre, Australia is the best modern analog for the Sunnyside Interval System is due to its morphological and stratigraphic similarities. Ultimately, we characterize the Sunnyside Interval System as a “Supply-Controlled Splay-Delta” with high sediment and water supply during transitory hyperthermal events and low sediment and water supply during inter-hyperthermal periods. The depositional system acted as both a terminal splay or a fluvially dominated delta guided by the interplay of supply and accommodation in Eocene Lake Uinta.

Human activities including fertilizer application and fossil fuel burning have increased nutrient concentrations in coastal waters. Nutrient inputs can be difficult to constrain at the coastal interface where multiple waters mix, including river water, groundwater, and lake or ocean water. At coastal interfaces, rivers distribute their nutrient loads across delta wetlands, where processes like anaerobic respiration and plant uptake may reduce nutrient concentrations. Beneath the coast, groundwater also carries nutrients offshore, where biogeochemical reactions alter the nutrient chemistry and discharge rates are difficult to measure. I aim to improve the assessment of nutrient loads to coastal waters in these challenging environments through two case studies. First, I estimate groundwater discharge, a previously unaccounted source of nutrients, to the United States Great Lakes coast using high-resolution geospatial analysis. By integrating land use data, I also identify areas of the coast that are vulnerable to high nutrient loads from groundwater. My analysis shows that almost one-third of Lake Erie’s United States coastline is vulnerable to contamination from groundwater nutrient sources. By collecting field measurements at a vulnerable beach site, I show that the nitrogen load from groundwater exceeds 1 gram/day/meter of coastline, which constitutes a small but non-negligible source to Lake Erie. In the second case study, I use benthic chambers to measure nitrogen removal rates in a coastal wetland in Wax Lake Delta, Louisiana. Results suggest that summertime nitrate removal kinetics are highly correlated with a widely available remotely-sensed vegetation index (NDVI). Heavily vegetated, submerged levees at intermediate elevations in the delta are thus predicted to be the most reactive habitats. Though less reactive, larger channels primarily on the eastern half of the delta may contribute most to nitrate removal, as they receive the greatest mass fluxes of nitrate. Numerical simulations of reactive nitrate transport in Wax Lake Delta and six synthetic deltas suggest that nitrate removal may be intrinsically limited in river-dominated deltas to a small fraction of the incoming nitrate load. Removal increases with delta topset gradient, and smaller, high-sitting deltas remove more nitrate than larger, low-lying deltas. From a management standpoint, nitrate removal efficiency can be improved by designing river diversions to build steeper deltas. Steeper deltas are created by accessing coarser sediments in river diversion projects. However, manmade deltas alone cannot remove most nitrate discharging to the sea. Policy that addresses the nitrate load upstream is necessary to further reduce coastal nitrate loading.

The (Campanian) Blair Formation (Fm), along the Rock Springs Uplift (a N-S, doubly plunging anticline) near the city of Rock Springs, Wyoming, comprises a stratigraphic 3rd order sequence set that included lowstand, transgressive, and highstand deposits. The Blair Fm was emplaced in shallow marine depositional settings (less than 100m of water) and contains deposits of offshore, prodelta , fluvial-dominated delta front, tidally-influenced delta front , wave-influenced delta front, and subaqueous terminal distributary channels. Delta deposits coarsen and thicken upward with variable degree of reworking by tidal(t) currents or waves(w) indicated by: sigmoids(t), single and double mud drapes(t), mud chips(t), and hummocky cross-stratification(w). No evidence of deep-water basin floor or slope deposits is present in the Blair. Additionally, the Blair is similar to other shallow marine deposits of the Cretaceous Western Interior Seaway (CWIS) that display a preferential tidal dominance during lowstand and preferential wave dominance during highstand. The Blair Fm evolves from lowstand, tidally-influenced deltaic deposits to transgressive offshore and prodeltaic deposits, and ultimately into highstand wave-influenced deltaic deposits. Local embryonic Laramide uplift and differential subsidence led to changes in the basin floor slope and geometry, likely steepening the formerly gentle, ramp-style geometry of the retroarc foreland basin, and inducing high sediment supply near local uplifts. Presence of delta-front turbidites to the north and prodeltaic mudstones in the south are indicative of the locally high sediment supply to the north. The changes in basin floor topography and/or steepening of the basinal slope are evidenced by the successive, meter-scale slumped intervals and a thickness anomaly within the middle Blair, along with amplification of tidal signatures in the lower Blair. This incipient uplift during the emplacement of the Blair may have occurred earlier (82 Ma) than the postulated earliest timing of uplift at around 80 Ma suggested by other workers. The Blair Fm is considered an unconventional (tight), heterolithic reservoir that produces mainly gas in hydrocarbon fields near the Rock Springs anticline. The lower Blair, heterolithic, tidally-influenced lowstand wedge deposits may serve as an analog for other lowstand tidal reservoirs of the CWIS, including the Frewens sandstone of the Frontier Fm

Recent reports estimate that the marshes of the Mississippi Delta receive just 30% of the sediment necessary to sustain current land area1. An extensive monitoring campaign by the USGS and LCPRA provides direct measurements of sediment accumulation, subsidence rates, and deposit characteristics along the coast over the past 10 years2, allowing us to directly evaluate this sediment balance. By interpolating bulk density, organic fraction, and vertical accretion rates from 273 sites, a direct measurement of organic and inorganic sediment accumulation can be made. Results show that a total of 82 MT/year of sediment is delivered to the coast. Using a fluvial sediment discharge of 113 MT/yr1, 52% of the riverine transported sediment is accumulated in the coastal lands of the Mississippi Delta. Assuming an average 9 mm/yr subsidence rate3 and 3 mm/yr sea-level rise1, this accumulation results in a 2.7 MT/yr (3.5%) sediment mass surplus. However, there is a 0.014 km3/yr (5.4%) sediment volume deficit caused by the sediment porosity being too small to fill the accommodation space. About 20 MT/yr inorganic and 6 MT/yr organic sediment initially accumulates in deltaic areas directly nourished by the Mississippi and Atchafalaya rivers, resulting in an initial sediment trapping efficiency of 18%. The remaining sediment must be delivered indirectly to the coast after passing through the ocean, accounting for another 39 MT/yr of inorganic sediment being trapped on coastal marshes. 17 MT/yr organic sediment is produced through marsh plant production. These results suggest that even if current relative sea level rise rates do not change, the gap between accommodation and accumulation is not as dire as previously thought.

We take a reduced complexity approach to assessing the advective factors that contribute to the hydrologic connectivity between a primary distributary channel and interdistributary island on the Wax Lake Delta of coastal Louisiana. We deployed a relatively inexpensive, open-source data logging platform to collect high quality continuous water temperature, water depth, air temperature, and shortwave solar radiation from a portion of Wax Lake Delta from February 18 through May 19, 2015. We use this field data to create a reference model of predicted water temperature at the data logging locations at the site. Based on comparison of that model with the water temperature observations, we find that different regions of the island have differing degrees of hydrologic connectivity to the primary distributary channel.

Abstract: The early Cambrian Mount Clark Formation of the Northwest Territories comprises marginal marine to marine siliciclastic sediments deposited in an incipient rift basin on the margin of Laurentia. Within core and outcrop datasets the preserved record of sedimentation represents complex and highly variable lateral to vertical architecture. As a result of recording early Cambrian (Series 2, Stage 3: Bonnia-Olenellus trilobites) the Mount Clark Formation represents a rare opportunity to study marine biological interactions at the very onset of the Cambrian Explosion. To achieve this objective, high resolution sedimentological ichnological data was recorded from a six core database within the Colville Hills in addition to the field description of 8 outcrops in the Mackenzie Mountains over the course of two field seasons. Eight distinct lithofacies (F1-F8) were identified in the Colville Hills recording offshore to continental deposition along a strongly storm-influence shoreface succession. Three distinct facies associations (FA1-3) were identified within the Mackenzie Mountains recording shoreface (FA1), deltaic (FA2), and tidal embayment (FA3) sedimentation. Shoreface sedimentation (FA1) ranged from strongly storm-influenced to storm-affected lower shoreface to foreshore environments and were identified on the presence of robust and diverse trace fossil assemblages. Deltaic sedimentation (FA2) ranged from strongly storm-influenced to storm-affected prodelta to upper delta-front environments and were identified on the basis of stressed trace fossil assemblages recording decreasing ichnofossil size, diversity, and abundance in collaboration with more immature lithologies. Tidal compound dune sedimentation (FA3) ranged from embayment margin to the core of a compound dune field. Shoreface trace fossil assemblages within both study areas were found to have higher degrees of diversity, abundance, and complexity than previously identified early Cambrian trace fossil assemblages. It is interpreted that the Mount Clark Formation represents the earliest known radiation into these characteristic ethologies predating the famous and complex body fossils within the Burgess Shale. This body of work seeks to highlight a poorly understood region of Canada’s north, recording deposition at a time when complex life was first inhabiting Earth’s primordial oceans.

This thesis focuses on the detailed design, implementation, and testing of a unique high performance rotary actuator for use in a custom haptic force feedback device. This six degree of freedom (DoF) position input and three DoF force output haptic device is specifically designed to recreate force sensations with the goal of improving operator performance in remote or simulated environments. By upholding the strict design principles of an ideal force-source actuator, the developed actuator and consequently the haptic controller can successfully replicate forces accurately and realistically. In the comprehensive presentation of this design, numerous analytical tools are also developed and presented with the intention of them being resourceful in the design or improvement of other haptic actuators, specifically cable-driven force feedback designs. These tools which include a linear system model can be valuable not only in the development but in the control of cable-driven actuators. Due to the imposed design criteria, the developed 1.045 Nm (1.359 Nm peak) cable-driven sectorial rotary actuator exhibits numerous properties that are desired in an open-loop force controlled actuator. These properties include low inertia (6.53e-04 kgm^2), low perceived mass (0.102 kg), small torque resolution (3.84e-04 Nm), small position resolution (21.5 arcsec), and high bandwidth (300 Hz). Due to the efficient cable transmission the design is also backdrivable, isotropic, low friction, and zero backlash. As a result of these numerous intrinsic properties, a high fidelity force feedback haptic actuator was conceived and is presented in this thesis.

River deltas are highly interconnected systems consisting of channels and inter-channel islands. They result from complex interactions between fluxes of water, sediment, nutrients, energy, and biota. Given the importance of deltas in a social, economic, and ecological context, the understanding of delta function and evolution is of utmost importance. This work aims to use statistical methods to gain insights into delta system processes across spatial and temporal scales. Specifically, understanding the effect of discharge, wind, and tidal forcing on delta variables is a key question. An information theoretic approach was used to identify environmental controls on island and channel inundation, and channel turbidities, in Wax Lake Delta, a naturally prograding delta in coastal Louisiana, USA. Continuous water level data were collected on the islands during summer 2014 and in the channels during winter 2014. Channel turbidities were also collected in winter 2014. Information theory statistics, such as transfer entropy and mutual information, were calculated for all variables to characterize controls on depth and turbidity in terms of strength, direction, and scale. Discharge, wind, and tidal forcing were found to be very dependent on spatial location in the delta. The more upstream locations see increasing influence from discharge in both islands and channels, with tidal influence increasing downstream. Channels are less affected by tides than islands. Wind influence is more complex and varies across space and time for both water level and turbidity. Recalculating information theory metrics under conditions of low and high discharge reveals a higher tidal influence in low flows and a higher wind influence during high flows. The implications for this work are the future construction of a process network, which will show the major flow paths of energy, water, sediments, and nutrients through the system, leading to enhanced metrics that aid in delta system restoration.

This paper focuses on the depositional environment of the “Clinton Sandstone” located in Perry, Fairfield, and Vinton Counties in central and southeastern Ohio. Core from wells numbered 2866, 2941, 2942, 2943, 2965, and 2980 were accessed from the Ohio Geological Survey, H.R. Collins Core Laboratory. Each core was described, photographed, and sampled for thin sections and lithofacies analysis. In addition, gamma-ray and neutron density logs were acquired for each well. The geophysical logs were used for litho-correlation and to examine 3-D architecture. This new data was used to re-evaluate the depositional interpretations.The “Clinton Sandstone” is an informal name given to the Lower Silurian sandstone unit that stratigraphically lies between the Cabot Head Shale and the Neagha Shale in southeastern Ohio. The “Clinton Sandstone” correlates with the Tuscarora Sandstone in Pennsylvania and West Virginia. Confusingly, the “Clinton Sandstone” is not related to the Upper Silurian Clinton Group located in western New York. Previous workers have interpreted the “Clinton Sandstone” to be part of a wide range of environments, from fluvial-deltaic to a strand plain, and incorporating tidal channels, delta plains, crevasse-splays, and offshore marine deposits. This study confirms some, but not all of the previous interpretations, finding the “Clinton Sandstone” to be part of a delta plain, delta front, and prodelta environment.There are a total of 16 lithofacies observed from the six cores studied. The dominant lithofacies are composed of sandstone, and include massive bedding, cross-bedding, planar lamination, shale partings (mud drapes), and mud intraclasts. There are also heterolithic sandstone-mudstone or siltstone-mudstone intervals with lenticular bedding, wavy bedding, and flaser bedding. Secondary features include ball-and-pillow structures. Mudstone is readily available and most of it is represented as mud drapes or thin intervals separating sandstone packages, or as mud intraclasts in sandstone. However, there are several large sections within the cores studied that contain around 1 m or more continuous mudstone. There are also thin 3 - 6 cm limestone intervals. These only appear toward the bottom in wells 2942 and 2943. These limestone packages are massive, and contain brachiopod fragments and bryozoans.These well samples show a strong tidal influence. Mud chips, mud drapes, and various shale partings are all negative factors that can lead to reservoir compartmentalization. Other features found that may contribute to poor reservoir quality are the tight nature of the grains, which contribute to low porosity and permeability. Quartz overgrowths are also present in these samples and have the potential to further hinder fluid flow as well as decrease the size and amount of pore space present.

The character and distribution of lithofacies in falling-stage deltas are incompletely documented. This paper presents a sedimentological and stratigraphic evaluation of a superbly-exposed interval of Cretaceous deltaic strata that are believed to be of falling stage origin. The studied interval forms part of the Upper Cretaceous (Turonian) Ferron Sandstone Member of the Mancos Shale in the southernmost Henry Mountains Basin of south-central Utah, USA. The interval of interest is exposed in three dimensions over a 20 km2 area in a series of canyon walls. Observed facies include fine-grained mudrocks (offshore basin), mudrocks with thinly interlaminated sandstone (prodelta), thinly interbedded siltstones and fine-grained sandstones (distal delta front), thickly interbedded siltstones, coarse-grained siltstones and fine-grained sandstones (medial delta front), and amalgamated fine- to medium-grained sandstones (proximal delta front). No facies of interpreted delta top origin were observed within the studied succession. The proximal delta front facies includes spectacular, chaotic sandstone-filled gullies up to 6 m deep and 300 m wide. The basal parts of these gully fills preserve large-scale convolute bedding, rotational failures and, in numerous places, growth faults. At least three such gully fills were noted, incised into different levels within the succession. The existence of three gully fills indicates episodes of delta progradation and sea level fall. Paleocurrent data indicate southeastward sediment dispersal. Facies stacking patterns and incised gully fills, together with the lack of a delta plain topset, argue strongly for a falling stage origin for the described succession. This study provides new insights into the facies architecture and stacking patterns of shallow-water, falling-stage deltas. In particular, the study illustrates a style of falling-stage deltaic system in which a descending regressive trajectory is difficult to discern. Adviser: Christopher R. Fielding

Delta islands make up the majority of coastal delta area. However, the groundwater hydrology of young, prograding delta systems and its relationship to surrounding surface water dynamics are poorly understood. Deltas in coastal environments are assumed to function as chemical “buffers”, filtering nutrient-rich terrestrial runoff through the island structures and surface water ecosystems as it travels to the sea, but the magnitude of this effect cannot be accurately quantified without understanding the physical relationships between the surface water and groundwater. This study developed the first conceptual model of the hydrology of prograding delta island groundwater systems. The study was based on field data collected at Pintail Island, a 2 km2 island within the Wax Lake Delta in Louisiana. Hydraulic properties and processes were quantified at multiple depths at locations spanning the island elevation gradient. Groundwater and surface water levels were monitored. A weather station recorded precipitation, air, and wind conditions. The groundwater within Pintail Island was both spatially and temporally dynamic throughout the study period of Sept/9/2013 to Feb/4/2014. The aquifer within the distal limbs of the island responded as a connected, saturated unconfined aquifer. The portions of Pintail Island within the older, proximal, higher elevation apex were found to be a two-layer system with fine sediments and organic matter overlying sandy deposits. The aquifer within this section of the island responded differently during times of elevated surface water (storm events) and times of normal surface water (calm periods) and differently from the distal-island unconfined system. The fine, shallow (roughly 0-60cm depth) sediments capping this older, higher portion of the island appeared to inhibit vertical flow between the surface and subsurface, creating semi-confined conditions within the sands in the deeper island subsurface. High water levels led to overpressurization of the apical aquifer, which was maintained between storms due to the low hydraulic gradient and the low permeability of the porous medium. During inundating storm events, groundwater potentials mimicked surrounding surface water levels. This conceptual model of a prograding coastal delta island now provides a foundation for further, hydrologically-realistic study of delta ecology and nutrient exchange.

Understanding how deltas build and maintain themselves is critical to predicting how they will respond to perturbations such as sea level rise. This is especially an issue of interest in coastal Louisiana, where land loss is exacerbated due to subsidence and decreased sediment supply. Feedbacks between ecology and geomorphology have been well documented in tidal environments, but the role of vegetation in delta morphodynamics is not well understood. This study investigates spatial and temporal correlations between vegetation succession and sediment accumulation at the Wax Lake Delta in Louisiana. I established a 2500 m long transect along the western levee of Pintail Island, capturing the full range of island elevations and the transition from bare sediment to herbaceous plants and trees. Shallow (50-100 cm deep) sediment cores taken along this transect were analyzed for particle size, organic matter content, and bulk density, and dated using ²¹⁰Pb. The resulting sedimentation rates and composition trends over time were compared to remote sensing-based analyses of temporal changes in island topography and flooding frequency derived from historical Landsat images. We found that the topography of Pintail Island has developed from a non-systematic arrangement of elevations to a discrete set of levees and intra-island platforms with distinct vegetation types, designated as high marsh, low marsh, and mudflat habitat. This elevation zonation is consistent with alternative stable state theory as so far applied to tidal salt marsh systems. At all but the youngest sampling site, sediment cores showed a significant decrease in organic matter content and a significant increase in grain size with depth. The total organic matter contribution to vertical growth was not sufficient to account for all the elevation change required to achieve the differentiation from low marsh to high marsh deduced from the time-lapse Landsat imagery analysis. Mineral sediment accumulation rates suggested that elevation growth was accelerating or holding steady over time, in contrast to theory suggesting rates should slow as elevation increases. These results provide an empirical foundation for future mechanistic models linking mineral sedimentation, organic sedimentation, vegetation succession, elevation change, and flood frequency in the delta.

Much work has shown that Parvalbumin+ (PV) interneurons, in particular the Fast Spiking Basket Cell, are major regulators of gamma-band activity in the cortex and hippocampus. Gamma rhythms, which are linked to attention, learning, and cognition, are depressed or altered in several key neurologic and psychiatric conditions, including schizophrenia and autism. Considerable evidence has demonstrated PV interneurons to be rigid regulators of neuronal activity, similar to a clock or a timer; however, in the past several years, evidence points to the ability of these cells to exert considerable modulatory influence on networks. For example, PV interneurons are surrounded by rings of dense extracellular matrix, termed perineuronal nets (PNN), which regulate plasticity in the visual cortex during development, as well as long-term potentiation and memory in the limbic lobe. Additionally, PV interneurons express extrasynaptic delta-subunit containing GABAA receptors (delta-GABAARs) that mediate tonic inhibition. In addition to regulating the excitability of these cells, delta-GABAARs are sensitive to levels of metabolites of progesterone and adrenal corticoids (i.e., neurosteroids), which are potent allosteric modulators of these receptors. Here, through a pharmacological and genetic model, we investigated the role of PV interneuron-expressed delta-GABAARs in behavior and neural rhythms. We show that ketamine, a non-competitive NMDA receptor antagonist shown to damage hippocampal PV interneurons, reduces and alters the PNNs surrounding these cells, as well as the expression of PV, and produces a behavioral phenotype consistent with schizophrenia. We next investigated the effect of conditionally knocking out the delta-GABAA receptor from PV interneurons. This resulted in altered gamma frequency and sensorimotor gating. Collectively, these results indicate that PV interneurons are capable of modulating cognition and behavior through tonic inhibitory currents. While other studies have demonstrated a role of tonic inhibition in behavior before, this is the first study to demonstrate interneuron-specific consequences of reduced delta-GABAAR expression.

A method for identifying stopped pions in a high-resolution scintillator bar detector is presented. I apply my technique to measure the axial mass MAΔ for production of the Δ(1232) resonance by neutrino, with the result MAΔ = 1.16 ± 0.20 GeV (68% CL) (limited by statistics). The result is produced from the measured spectrum of reconstructed momentum-transfer Q2. I proceed by varying the value of MAΔ in a Rein-Sehgal-based Monte Carlo to produce the best agreement, using shape only (not normalization). The consistency of this result with recent reanalyses of previous bubble-chamber experiments is discussed.

I analyze the effect of various risks faced by commercial banks on the executive compensation in banking industry. Commercial bank executives are risk averse due to the regulatory pressure in addition to board governance mechanism. Commercial banks face various risks because of the regulatory mechanism and unique asset structure of the firm. So, it is expected that they should associate their own pay and pay-performance sensitivities (PPS) with the risks their banks face. I find that bank executives associate their performance based pay with both idiosyncratic risk and systematic risk. But they associate their fixed pay only with systematic risk. The risk based PPS is also affected by the idiosyncratic risk but not by the systematic risk. Both asset return risk and insolvency risk have significant positive effect on PPS. Bank executives put significantly higher emphasis on the fixed compensation in terms of salary and bonus, and significantly lower emphasis on the performance based compensation. They also put minimum emphasis on the risk based PPS although they put significant emphasis on return based PPS. These indicate the risk-averse nature of the bank executives due to the regulatory pressure in addition to board governance mechanism.

Deltaic systems have long been recognized for their socioeconomic impacts as well as their high potential to trap and store hydrocarbons. The Sediment Transport and Earth-surface Process (STEP) basin at the University of Texas at Austin has the ability to create large 3D physical experiments, designed for nurturing new understanding of these systems and the parameters that influence their evolution. We explored how a laterally tilting basin influenced a prograding fluvio-deltaic system. The tilting occurs along a rotational axis, bisecting the model’s basement and allowing the delta to experience uplift in one half of basin and subsidence in the opposite half. After six experiments with a range of tilting rates, we observed that varying rates of tilting changed progradation patterns as well as the resultant stratigraphy. The tectonic tilting forced a continuous change in topset slope, which accounts for the evolving behavior of the fluvial system with regards to channel occupation and thus shoreline asymmetry. When slow tilting was applied, the delta advanced faster in the direction of uplift due to the relative decline in basin water depth. This created truncated stratigraphic intervals dominated by active channel cut and fill with thin but laterally linked channel bodies depositing finer material. Behavior was significantly different on the subsidence side of the delta; shoreline migration was stunted while the delta became primarily aggradational, depositing thicker, alternating packages of sands. During higher rates of tilting, deposition at the uplift end was quickly abandoned and instead focused on stacking conformable sequences of delta lobes in the area of increased subsidence, resulting in a complete lack of progradation in any direction. Progressively greater rates of tilting yielded more dramatic steering of channelized flow toward the area of greatest subsidence. Comparing characteristic tectonic and channel timescales proves to be a good predictor of shoreline symmetry along with sediment distribution due to differential subsidence. In this study, we tested the hypothesis that differential subsidence acting on the Ganges-Brahmaputra (G-B) system is responsible for delta asymmetry. The asymmetry in planform shoreline geometry and subsurface stratigraphy of the G-B delta system are extensively similar to the experimental results.

Raster log images were analyzed to study the subsurface stratigraphy of the Middle Atoka in the Arkoma Basin of the western portion (Sebastian County) of Arkansas. The most significant sandstone units of the Middle Atoka in this area were determined to be two generally coarsening-upward sequences in the lower portion of the formation. Based on lithologic correlations, these two units were determined to be the informally named Casey and Freiburg members of the Middle Atoka. Thickness information based on picked tops was used to create isopach maps of the units of interest. The log signatures and geometry of the sand bodies indicate that they were deposited in a deltaic system that prograded across this portion of this basin. Distributary-mouth bar deposits dominate the Casey member, and are occasionally overlain by localized channel deposits. Avulsion of the delta lobe possibly occurred, and a new lobe then began to prograde, depositing the sediments that formed the Freiburg. This unit is also dominated by distributary-mouth bar deposits.

The well-known clinoformal geometry of a basin-fill, with an alluvial to shelf segment, deep-water slope segment, and a basin floor segment, arises from the development of a wedge-shaped body of sediment at the basin-margin that has been termed a basin-margin wedge or a shelf-slope sedimentary prism. The basin-margin wedge characteristically has atopset-foreset clinoformal geometry, with its topset dominated by alluvial, coastal and shelfal processes, while its foreset is dominated by turbidite sedimentation. Tectonic configuration of the basin, sediment supply, and relative sea level variation are some of the major factors that control the development and growth of the basin-margin wedge. This dissertation documents two distinct stages of development of the basin-margin wedge at an Eocene active margin, and relates the observed variability in the nature of the shelf-margin, deep-water slope, and basin-floor deposits with these stages. The Tyee Basin in western Oregon was a forearc basin that was filled during late early Eocene and Middle Eocene under greenhouse climatic condition. The sedimentary succession of the Tyee Basin include continental, shallow-marine and deep-water sandstones that are well exposed in Coast Range area of Oregon. The variability observed within the thick and laterally extensive turbidite sandstones of the Tyee Basin led to contrasting depositional models for the Tyee basin in the past. Notably, the submarine ramp model, which provides an alternative model for deepwater coarse clastic deposition, was proposed based on the sedimentary succession of the Tyee Basin. Reconstruction of the clinoformal geometry of the Tyee Basin succession from detailed field data (more than 1000 outcrop locations) and subsurface data reveals two distinct stages of development of this active basin-margin. Each stage has a distinct style of clinoform development and a distinct character of associated sandy deepwater deposits. At the initial stage the basin-margin clinoforms appear to be small (< 250m clinoform height) and strongly progradational, with clinoform topset dominated by the feeder fluvial deposits. At this stage, sandy unconfined (not channelized) turbidite deposits accumulated on the Tyee deepwater slope and extended to the Tyee basin-floor. Large scale sediment conduits on the deepwater slope, in the form of slope channels or canyons, are notably absent in this stage. The second stage is characterized by larger clinoform height (> 500m), higher degree of topset aggradation with repeated fluvio-deltaic cycles on the shelf, and spectacular, sand-rich, well-organized turbidite channels and canyons on the slope. The slope channels active at this stage supplied coarse sediments to the basin-floor to form unusually thick basin-floor fans. The first infill stage represents the embryonic development of a basin-margin wedge on the Tyee continental margin, and could have some similarity with the previously mentioned submarine ramp model. But this was followed by a much longer period of basin-filling when repeated fluvial and shallow-marine cycles formed on the shelf and well-organized turbidite channels were active on the slope supplying sands to the Tyee Basin floor fans. It was concluded that the two stages of development of the basin-margin wedge in the Tyee Basin is controlled largely by the configuration of the basin, that is a result of the prominent topographic/bathymetric features in oceanic basement underlying the sedimentary succession of the Tyee Basin. Tectonically active hinterland and greenhouse climate may have contributed to a relatively high sediment supply to the basin. The relatively small-amplitude sea level variations expected under greenhouse climatic condition of the Early to Middle Eocene are likely to have relatively minor effect on the architecture of the basin-fill. The present work on Tyee Basin builds on earlier research on this basin, but now establishes a ground trothed clinoformal growth model, revises the existing interpretation of sediment transport direction during a major part of the basin-filling history, and demonstrates a two-stage evolution of margin accretion. The observations from the active Tyee Basin was compared and contrasted with a latest Pleistocene sediment wedge on the New Jersey outer shelf. This sediment wedge, developed under icehouse climatic condition, and on a passive margin, was studied using high resolution seismic data (CHIRP). In contrast to the sedimentary succession of the Tyee Basin, the depositional architecture of the sediment wedge on outer New Jersey shelf, which was interpreted as a set of falling stage deltaic clinothems, appears to be strongly controlled by eustatic sea level variation of latest Pleistocene.

The development and advancement of new laser scanning techniques enables the capture of 3D imaging which can be quantitatively assessed for use on the human skull. I used a Polhemus Fast Scan Scorpion scanner to scan 8 skulls and evaluated the standard 24 metric measurements in Delta analysis software in comparison to standard metric measurements. The scanned measurements were then compared to the standard metric measurements using the same landmarks. Of the original 48 measurements, 33 (68.75%) fail to reject the null and 10 (20.83%) reject the null with the remaining 5 (10.41%) being unknown due to n=1 because of skull damage. The measurements that proved highly reliable were those associated with specific landmarks, and not those measurements that are based on landmarks and feel and considered arbitrary in this study. This study indicates that the use of the laser scanner can be a useful tool for rapid acquisition of skeletal and anatomical surfaces however, accurate location of landmarks and operator skill are of utmost importance in achieving accurate and reliable results.

Notch signaling is important for cell-cell signaling during development. Notch signaling is highly conserved across all metazoans and failure in Notch signaling is causative in many human diseases. In the Drosophila eye, activation of the Notch pathway requires Lqf (Drosophila Epsin)-dependent and Clathrin-dependent internalization of the Notch receptor ligands, Delta or Serrate, by the signal-sending cells. However, it is unclear why ligand must be internalized into the signal-sending cells to activate Notch signaling in the signal-receiving cells. Evidence suggests that in addition to Clathrin and Epsin, Auxilin is essential for signaling and is indirectly required for internalization of the Notch receptor ligand Delta. Auxilin functions in uncoating Clathrin-coated vesicles to maintain a pool of free Clathrin and Epsin in the cell. auxilin mutants were used as an entryway to identify previously unknown components of the Notch signaling pathway. An F1, FLP/FRT, EMS screen was performed and enhancers of an auxilin mutant rough eye defect were isolated. The enhancers ultimately formed one complementation group on the 2nd chromosome and fourteen complementation groups on the 3rd chromosome. Three of the 3rd chromosome complementation groups were each identified as Delta, lqf, or hsc70. A single allele was identified as faf. Delta and Epsin have known roles in signaling cells to activate Notch as described above. Hsc70 is an ATPase that functions with Auxilin to uncoat Clathrin-coated vesicles and Faf is a deubiquitinating enzyme that maintains levels of active Epsin in the cell. These results suggest I have isolated mutations in genes closely tied to Notch signaling or functioning directly with Auxilin. Mutations in two genes previously undescribed in Notch signaling in the developing Drosophila eye were also isolated from the screen and identified. The second chromosome complementation group was identified as α-adaptin. α-Adaptin is a subunit of the heterotetrameric Clathrin adaptor protein AP-2. One of the third chromosome complementation groups was identified as crumbs. Crumbs is an integral membrane protein that functions at adherens junctions and in establishing apical/basal polarity in cells. Characterizing roles for α-Adaptin and Crumbs during Notch signaling may elucidate the purpose for Delta internalization to activate Notch signaling.

Aqueous deposits are an essential key to understanding the geologic/climatic history of water on Mars. The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), High Resolution Imaging Science Experiment (HiRISE), and Thermal Emission Imaging System (THEMIS) have enabled studies of Martian fan deposits in unprecedented detail, including the identification of hydrated minerals (such as phyllosilicates, carbonates, and sulfates) and morphologies consistent with formation in an aqueous environment associated with Martian sedimentary deposits. In this study, twenty-six previously identified fan-shaped deposits (hypothesized as possible deltas) have been examined for hydrated minerals in the beds and distal regions of the deposits. Six deposits have newly been identified to bear phyllosilicates (primarily Fe/Mg-smectites) and are characterized herein with regards to mineralogy, morphology, and thermophysical properties. The results of these analyses suggest that at least four of these deposits are consistent with formation in a deltaic environment; though other possible formation environments, such as alluvial fans and alluvial fan-deltas, should not be altogether excluded, as some of the deposits also bear resemblances to terrestrial examples of such features. The results of this study are consistent with Mars once having hosted aqueous environments in which flowing and standing water was sustainable on the surface, allowing the formation of deltas on Mars.

Increasing municipal and regional water demands have reduced freshwater inflows to the Nueces Delta. These flow reductions impair the marsh ecosystem’s functionality. As part of a United States Army Corps of Engineers multi-agency collaboration to restore the Nueces River and its tributaries, we have developed a mass-conservative hydrodynamic model to analyze fate and transport of freshwater and tidal inflows to the Nueces Delta. The model is built upon the LIDAR bathymetric data collected by the Coastal Bend Bays and Estuaries Program (CBBEP). Input data includes tidal, salinity, and wind data obtained from the Texas Coastal Ocean Observation Network (TCOON), pumping data from the Nueces River Authority, precipitation data from NOAA, and river flow from the USGS. The underlying modeling method uses conservative finite-difference/volume discretization on a Cartesian rectangular grid to simulate the movement of water and salt fluxes across the delta. Sub-models to represent the hydraulic influence of flow constrictions (e.g. railroads trestles, culverts) have been developed. The model’s response to forcing from wind, precipitation, and roughness were analyzed. The time to spin up for the model was analyzed and found to be approximately seven days. Preliminary validation of the model was qualitative but the overall trend of the tide coming in appears correct at the monitoring stations analyzed, indicating that the lowest frequency forcing of the tide and wind are correct. The effects of pumping into the delta were investigated under different pumping conditions to reveal the area inundation and impacts on salinity from pumping.

The study area is situated along the obliquely converging boundary of the Caribbean and South American plates offshore eastern offshore Trinidad. Major structural elements in the shelf break and deep-water slope regions include normal and counter-normal faults to the south and large transpressional fault zones to the north. Well logs and biostratigraphic information were analyzed for twenty-four wells in the study area to refine previous depositional environment interpretations. For purposes of this net sand distribution analysis it was decided to consider the deltaic portion of the shelf transit cycle, against the marine portion of the shelf transit cycle and were named T and R cycles, respectively. T and R cycles were interpreted based on well log patterns and depositional facies shifts. Six T/R cycles were interpreted within the Pliocene to recent stratigraphic succession and shelf edge trajectories were also mapped for each of these cycles based on earlier stratigraphic correlations. Net-to-gross (NTG) ratios were calculated for each component of the T/R cycles and plotted against total thicknesses and net sand values. In addition, NTG trends were mapped for each interval and analyzed based on their proximity to the corresponding shelf edge. Mapping of the shelf edge trajectories (SET) revealed that (1) SET migrate northeasterly across the Columbus Basin through time and (2) shelf edge orientations are parallel to the strike of growth faults in the south but deflect to the northeast near the Darien Ridge indicating a strong underlying structural control. The NTG plots and maps also revealed that (1) For T cycles, NTG values never exceed 60% and are inversely proportional to total thickness, (2) For R cycles, NTG values are highly variably ranging from 35% to 90%, (3) NTG values increase as the shelf break is approached and (4) The distribution of NTG ratios is also controlled by accommodation space created by local structures. The Guiana current is believed to play an important role in the redistribution and reworking of sand in the Columbus Basin. Aggradation and progradation distances were computed for each interval and the results suggest that the younger Sequences C2 (T-R cycle E) and C3 (T-R cycle F) show a stronger progradational trend than the older C4, C5 and C6. This strong progradational trend might indicate delivery of sand basinwards, while for the older intervals; the aggradational trend suggests an increase in sediment storage. In long-term scale (1-2 m.y.) the Orinoco Delta seems to behave as an aggradational delta that increases sediment storage due to growth fault and high subsidence rates. However, in the short-term scale, the Orinoco delta seems to behave as a rapid progradational delta, for the younger sequences C2 and C3, where sediment bypass is more likely to occur; and as a rapid aggradational (slow prograding) margin for the older intervals C4, C5 and C6.

Notch signaling is an evolutionarily conserved developmental pathway regulated by two classes of transmembrane proteins: the Notch receptors and the Delta/Serrate/LAG-2 (DSL) ligands. Notch and DSL ligands mediate cell-cell communication that results in a downstream signaling cascade that affects many aspects of metazoan development. Additional regulatory mechanisms that affect Notch signaling are being discovered continuously, and recent findings highlight the importance of endocytosis, ubiquitylation and subcellular trafficking as essential requirements for proper signaling. In order to obtain further insights into the regulation of Notch signaling, I took a two-fold approach, combining genetic and molecular techniques in Drosophila. First, I took part in a large-scale transposon-based screen in the developing Drosophila eye to identify additional genes involved in the pathway. We screened 10,447 transposon lines from the Exelixis collection for modifiers of cell fate alterations caused by overexpression of Delta, and we identified 170 distinct modifier lines that may affect up to 274 genes. I further analyzed a previously uncharacterized gene, which we have named Amun, and showed that it localizes to the nucleus and contains a putative DNA glycosylase domain. Further analyses of Amun reveal that altered levels of Amun function interfere with cell fate specification during eye and sensory organ development. Second, to investigate structural requirements for ubiquitylation of Delta, I analyzed four individual lysine residues in the Delta intracellular domain, and assessed their necessity for Delta signaling activity. I find that a conserved residue, DeltaK742, is essential for Notch signaling in the Drosophila imaginal wing disc and is apparently required for ubiquitylation of Delta by the E3 ubiquitin ligase, Mind bomb1 (one of two E3 ubiquitin ligases required for Delta signaling activity). Taken together, the findings from this thesis research contribute to the advancement of our understanding of different aspects of Notch signaling and Notch-mediated development.

Analyzing the performance of large-scale scientific applications is becoming increasingly difficult due to the sheer size of performance data gathered. Recent work on scalable communication tracing applies online interprocess compression to address this problem. Yet, analysis of communication traces requires knowledge about time progression that cannot trivially be encoded in a scalable manner during compression. We develop scalable time stamp encoding schemes for communication traces. At the same time, our work contributes novel insights into the scalable representation of time stamped data. We show that our representations capture sufficient information to enable what-if explorations of architectural variations and analysis for path-based timing irregularities while not requiring excessive disk space. We evaluate the ability of several time-stamped compressed MPI trace approaches to enable accurate timed replay of communication events. We evaluate our timing methods against various stages of compression to study the effects of compression on timing accuracy. Specifically, we measure accuracy by comparing the original application execution times with the compressed trace replay times. Our lossless traces are orders of magnitude smaller, if not near constant size, regardless of the number of nodes while preserving timing information suitable for application tuning or assessing requirements of future procurements. Our results prove time-preserving tracing without loss of communication information can scale in the number of nodes and time steps, which is a result without precedent.

The positive link between educational attainment and improved socioeconomic outcomes under the auspices of the current economic environment is essential to the survival of rural states like Mississippi, which has some of the nation's lowest educational attainment and income levels. One of the most promising education policies for Mississippi is related to research on school size, district size, and positive educational outcomes among students. Smaller schools and districts are increasingly being touted as the basis for rural school reform, renewed economic development efforts in rural communities, and cost effective means to overcoming barriers poor students face in graduating high school and scoring higher on state achievement tests. However, data from Mississippi indicates school size and district may function differently in the state. This study explores school size at the high school level and at the district level, using Mississippi as a case study. It incorporates socioeconomic well-being factors associated with influencing student outcomes for the state's public high schools.

The purpose of this study is to document the nature of sedimentation on the inner shelf of the East China Sea (ECS), with particular interest in the fate of the Yangtze River sediment. The Yangtze River has discharged about 500 million tons of sediment annually. High-resolution Chirp Sonar seismic data and shallow cores reveal a broad mud wedge up to 100 km wide extending 800 km southward along the Zhejiang-Fujian coasts. The mud wedge is thickest (~ 40 m) between the 20 m and 30 m isobaths and progressively thins offshore reaching water depths up to 60 and 70 meters. The mud wedge has a clinoform morphology with gently dipping topset, steeply dipping foreset, and gently dipping bottomset beds. 14C age dates indicate the clinoform began to form around 7000 yrs BP after sea-level reached the middle Holocene Highstand stage and decelerated to its present position. Sediment accumulation rates were estimated from the vertical distribution of excess 210Pb in sediment cores collected at 8 stations along the inner shelf. Near the mouth of the Yangtze River sediment accumulation rates have historically been about 1 to 5 cm y-1, due to winter resuspension and erosion events. The highest apparent accumulation rates in the mud wedge (2.1 cm yr-1) were found just south of the Yangtze estuary (30.5°N). Apparent accumulation rates generally decrease alongshore toward the south and offshore toward the east (~ 1.6 - .33 cm yr-1). This pattern is consistent with the dispersal of Yangtze River-derived sediments by the Chinese coastal current and tidal systems. A calculated sediment budget using Pb-210 apparent accumulation rates (100-yr time scale) indicates that 35% of the sediment annually accumulating in the inner shelf mud deposit can be accounted for in the sediments north of 30°N. This portion of the inner shelf mud deposit accounts for 55 % of the annual sediment discharge from the Yangtze River. Surface sediments of the inner shelf mud wedge are composed of clayey-silts and silty-clays. Coarser grained sandy-silts and silty-sands identified from cores on the thin bottomset deposits are a mixture of the fine Yangtze River sediment and coarse relict sands. Clay mineral assemblages of the mud wedge are composed primarily of illite (generally more than 70 %), and subordinately of chlorite, kaolinite and smectite. Smectite concentrations (< 5 %) are a good indicator that the sediments are derived from the Yangtze River.

This study aims to establish a depositional framework for an area of the Louisiana shelf, north-central Gulf of Mexico. The depositional history of the study area is poorly understood, especially within the last cycle of major eustatic fluctuation (~18, 000 yrs BP – present). Data sets used in this study include pre-existing and previously unanalyzed two-dimensional, highresolution seismic profile records (Acadiana 86 and Acadiana 89), geotechnical foundation boring data (Coleman and Roberts, 1988a), and an industry lease block survey report (Cole, 1983). Seismic sequence stratigraphic methods are employed in this study to analyze seismic profile data. Seismic sequence analysis results indicate the presence of five unconformable surfaces and five seismic facies units. Through correlation of seismic profile data with lithologic and chronologic data, it is possible to conclude that these seismic facies units represent shelf-margin deltaic deposition during the last lowstand of sea level (~18, 000 yrs BP), sourced by the Pearl River. .

The existence of three types of opioid receptors, delta, mu and kappa, as well as their analgesic effects, and associated side effects are well known. Although thousands of opioid peptides and non-peptides have been synthesized, an understanding of the individual pharmacological activity of each receptor type, and the development of analgesics with no adverse side effects are still great challenges. A detailed knowledge of opioid receptor structure and the interaction of opioids at the receptor-binding site are keys for meeting these challenges. This thesis describes structure activity relationship (SAR) studies on two potentially valuable classes of small opioid ligands, Tyr-Tic and BTTQ (6-benzyl-4-tyrosyl-1,2,3,4-tetrahydroquinoline) and relates the observed results to our evolving opioid receptor models. In the Tyr-Tic series, extensive structural modifications performed on the Ti(c) (1,2,3,4-tetrahydroisoquinoline-(3-carboxylic acid)) benzene ring lead to generally decreased delta binding affinities, although lipophilic substituents such as Cl, F and Me are better tolerated. Modifications on various other positions fail to produce promising binding results. Conformational analysis of Tyr-Ti(c) using a grid scan search method with dihedral angles chi 1, y and o as variables identified low energy conformers, which were grouped into conformational families. Comparison with the structurally rigid opiate naltrindole and docking to our receptor model identifies the delta bound conformation of Tyr-Ti(c) as containing trans and gauche (+) orientations of Tyr1 and Tic2 side chains, respectively, a y angle of Tyr1 ∼ 130° and a cis peptide bond. Interactions of ligands with opioid receptor binding sites were also examined. The results are in general agreement with the observed SAR data. BTTQ was designed based on a pharmacophore model derived from the cyclic tetrapeptide peptide cyclo[Tyr-D-Cys-Phe-D-Pen] (JOM-13) with the entire cyclic portion of the peptide replaced by the tetrahydroquinoline scaffold. Various substituents were incorporated at the N1 position through a rationally designed synthetic pathway. The binding data are consistent with the modeling results that predict that a negatively charged group should improve mu binding affinity and decrease kappa binding affinity, while a positively charged group should increase kappa binding and diminish mu binding, although the magnitude of the changes observed is small.

The conformationally restricted, delta opioid receptor selective tetrapeptide H-Tyr-D-$\rm C\overline{ys-Phe-{\it D}-Pe}nOH,$ cyclized by disulfide formation between side chains of residues 2 and 4, was modified at each residue to allow comparison with the cyclic disulfide-containing pentapeptide analogs of (D-Pen$\sp2$, D-Pen$\sp5$) enkephalin (DPDPE). Analogs of the template tetrapeptide were designed to explore the biological consequences of substitution of amino acids with varying steric, electronic, lipophilic, and/or chiral properties at each residue. Effects on binding affinity and selectivity at mu and delta opioid receptors and on bioassay potency were evaluated. Analogs investigating the effect of the orientation and the nature of side chain aromatic functional moieties were prepared. Modifications which were expected to influence backbone and side chain conformation at each residue, as well as variation in the cyclic portion of the molecule, also were examined. Data indicated that structure-activity relationships developed for pentapeptide enkephalins often were inapplicable to the tetrapeptide series. In general, where direct comparisons were possible, structural requirements for the Phe$\sp3$ residue in this tetrapeptide series were less stringent than in the related pentapeptide series. These findings suggest possible differences in the manner in which the Phe$\sp3$ residue of dermorphin-like tetrapeptides and the Phe$\sp4$ residue of enkephalin-like pentapeptides interact at delta opioid receptors; however, other interpretations are not excluded. Distinctions between the series in elements of the binding interaction also were notable at other residues. These peptides lack the central glycine residue of enkephalin analogs, therefore resembling dermorphin, and can be expected to possess a higher degree of rigidity and structural definition, an effect to which results may be attributed. They thereby represent a more credible series for analysis of the structural and conformational features required for peptide ligand binding at the opioid receptor types. In addition, comparison of the effects of analogous modification between the cyclic tetrapeptides and the restricted pentapeptides allows examination of the proposal that different subsites of the delta receptor may be involved in the binding of the two series.

Relative sea level stand and sedimentation in the Late Pennsylvanian and Early Permian Pedregosa basin of the southwestern margin of North America was controlled by a complex interplay of local tectonism and eustasy. Coarse, terrigenous sediments derived from a metamorphic terrain occur in the Virgilian-aged basin, providing evidence for the uplift of the nearby Florida-Burro High in mid-Virgilian time. Megabreccias coincide with the clastics; they formed during times of tectonic activity and relative lowstand of sea level. In the Early Wolfcampian, basinal megabreccias are slightly older than a shelf limestone which sits unconformably on basement in the Florida-Burro area. The accumulation of megabreccias in the basin without concommitant terrigenous clastics marks the downdrop of the Florida-Burro horst in the Early Wolfcampian. During this tectonically active interval from Virgilian to Early Wolfcampian, the paleobathymetry of the basin did not correspond to eustatic sea level changes. The Missourian and later Early Wolfcampian bathymetry, however, did correlate with eustatic changes, indicating that both local tectonism and eustasy controlled sedimentation and sea level. Diagenetic facies of sediments from the basin and slope were not regularly distributed according to sedimentary facies as they are on the Midcontinent. This was a result of tectonic influence on sea level stand. Overlapping freshwater lenses were detected in Wolfcampian-aged bioherms, and freshwater alteration was also seen in three lower horizons. Dolomitization among the basin-slope facies occurred during burial; the extent of dolomitization was related to the length of time the sediment rested just beneath the sediment-water interface, the original texture of the sediment, and sea level stand during deposition. $\delta\sp{13}$C varied in a secular fashion from 2.5$\perthous$ in the Missourian to 4.8$\perthous$ in the Early Wolfcampian, and to 2.0$\perthous$ later in the Early Wolfcampian. The trend was not related either to changes in local paleobathymetry or to regional eustasy. It was found that diagenesis may significantly alter original $\delta\sp{13}$C of primary micrites, and thus care must be taken to avoid diagenetic overprint.

This dissertation considers the fixed-structure, discrete-time ${\cal H}\sb2$ and mixed ${\cal H}\sb2/{\cal H}\sb\infty$ controller synthesis problem in the delta-operator (difference operator) framework. A decentralized static output feedback formulation is used as a general framework for posing fixed-architecture robust controller synthesis problems. A unified treatment of the ${\cal H}\sb2$ and mixed ${\cal H}\sb2/{\cal H}\sb\infty$ problems using the difference operator, differential operator and shift operator is presented, and relationships between these norms for the different operators are developed. For fixed-structure synthesis, necessary conditions are derived for all three operator formulations. The extended matrix pencil algorithm of Van Dooren is extended to to solution of delta operator (difference operator) algebraic Riccati equation to provide uniform computational algorithms for all operator formulations. A hybrid quasi-Newton/continuation algorithm is used to obtain approximate solutions to these equations. Controllers are synthesized for several numerical examples, and the performance of the algorithm on the differential, difference, and shift operator versions of these examples is compared. The synthesis technique is then applied to difference operator-based discrete-time, reduced-order ${\cal H}\sb2$ and mixed ${\cal H}\sb2/{\cal H}\sb\infty$ controller design for noise suppression in an acoustic duct. Experimental closed-loop performance and robustness of the resulting reduced-order ${\cal H}$ and mixed ${\cal H}\sb2/{\cal H}\sb\infty$ controllers are compared to simulations based on the identified model.