Physical Sciences and Mathematics Commons^™

Preservation And Erosion Of Theropod Tracks In Eolian Deposits: Examples From The Middle Jurassic Entrada Sandstone, Utah, U.S.A., Jesper Milán, David B. Loope

David B. Loope

The Middle Jurassic Entrada Sandstone, exposed near the town of Escalante, southern Utah, consists of large-scale cross-bedded eolian deposits that are interbedded with horizontally laminated sand sheets and thin sets of eolian cross-strata, representing periods with a moister climate. The flat-bedded units contain numerous tracks and trackways from small to large-sized theropod dinosaurs. These tracks are today exposed in several distinct erosional states, allowing detailed studies of track and undertrack formation in eolian deposits. Tracks that originally were emplaced on sloping surfaces show, in their present-day erosional state, a morphology distinct from those originally emplaced on horizontal surfaces. Further, the …

Tropical Westerlies Over Pangaean Sand Seas, David B. Loope, Maureen B. Steiner, Clinton M. Rowe, Nicholas Lancaster

David B. Loope

Cross-equatorial, westerly winds are key features of tropical circulation in monsoonal regions. Although prominent in numerical climate models of Pangaea (the supercontinent straddling earth’s equator, Late Paleozoic to Early Mesozoic), such flow has not been confirmed previously by migration directions of ancient dunes. Windblown sandstones that span 100 million years of earth history are widely exposed in south-western USA. If recent paleomagnetic data from the Colorado Plateau are used to correct Mesozoic paleogeographic maps, the Plateau is placed about 10° further south than previously assumed, and the prevailing north-westerly surface winds recorded by dune-deposited sandstones are explicable as cross-equatorial westerlies …

Atlantic And Pacific Sst Influences On Medieval Drought In North America Simulated By The Community Atmospheric Model, Song Feng, Robert Oglesby, Clinton M. Rowe, David B. Loope, Qi Hu

David B. Loope

Severe drought is arguably one of the greatest recurring natural disasters that strikes North America. A synthesis of multiproxy data shows that North America was in the grip of a severe centennial-scale drought during medieval times (800–1300 AD). In this study, the Community Atmospheric Model (CAM) is used to investigate the role of sea surface temperature (SST) anomalies from the North Atlantic and the tropical Pacific Ocean on this megadrought. These anomalies are obtained from proxy reconstructions of SST. Four model experiments with prescribed SST anomalies in the tropical Pacific and/or North Atlantic Ocean were made. The CAM results captured …

Burrows Dug By Large Vertebrates Into Rain-Moistened Middle Jurassic Sand Dunes, David B. Loope

David B. Loope

In south-central Utah, eolian cross-strata of the Escalante Member of the Entrada Sandstone contain inclined, cylindrical burrows up to 63 cm in diameter and 305 cm long. Of the 14 large tunnels located during this study, 12 descend from second- and third-order bounding surfaces that formed on the lee slopes of large dune ridges, well above the water table. The tunnels are inclined 15°–22°; one tunnel ends in an expanded chamber. Eolian cross-strata fill proximal portions of four of the tunnels and indicate that after abandonment, sand drifts migrated as much as a meter into the open shafts. Structureless sand …

Inconsistencies Between Pangean Reconstructions And Basic Climate Controls, Clinton Rowe, David B. Loope, Robert J. Oglesby, Rob Van Der Voo, Charles E. Broadwater

David B. Loope

The supercontinent Pangea dominated our planet from the Permian into the Jurassic. Paleomagnetic reconstructions have been used to estimate the latitudinal position of Pangea during this 100-million-year period. Atmospheric circulation, recorded by eolian sandstones in the southwestern United States, shows a broad sweep of northeasterly winds over their northernmost extent, curving to become northwesterly in the south. This evidence is consistent with paleomagnetic reconstructions of the region straddling the equator in the Early Permian but is at odds with its northward movement to about 20°N by the Early Jurassic. At least one of the following scenarios must be true: the …

Modern And Late Holocene Wind Regimes Over The Great Plains (Central U.S.A.), Rebecca L. Schmeisser, David B. Loope, Joseph A. Mason

David B. Loope

The Great Plains of the central United States contain numerous presently stabilized dune fields that were active during the late Holocene. The most recent period of reactivation occurred about 700–1000 years ago during the Medieval Climatic Anomaly, a period of frequent, severe drought recognized throughout the North American West. Dune orientations and internal bedding preserve information about paleowinds from this time period. We compared paleowind information with modern winds and potential sand transport analyzed from meteorological data. While both reconstructed paleowinds and modern winds include a strong northwesterly component over the northern to central portions of the Great Plains, a …

Late Pleistocene Dune Activity In The Central Great Plains, Usa, Joseph A. Mason, James B. Swinehart, Paul R. Hanson, David Loope, Ronald J. Goble, Xiaodong Miao, Rebecca L Schmeisser

David B. Loope

Stabilized dunes of the central Great Plains, especially the megabarchans and large barchanoid ridges of the Nebraska Sand Hills, provide dramatic evidence of late Quaternary environmental change. Episodic Holocene dune activity in this region is now well-documented, but Late Pleistocene dune mobility has remained poorly documented, despite early interpretations of the Sand Hills dunes as Pleistocene relicts. New optically stimulated luminescence (OSL) ages from drill cores and outcrops provide evidence of Late Pleistocene dune activity at sites distributed across the central Great Plains. In addition, Late Pleistocene eolian sands deposited at 20–25 ka are interbedded with loess south of the …

Dinosaur Tectonics: A Structural Analysis Of Theropod Undertracks With A Reconstruction Of Theropod Walking Dynamics, Ole Graversen, Jesper Milán, David B. Loope

David B. Loope

A dinosaur trackway in the Middle Jurassic eolian Entrada Sandstone of southern Utah, U.S.A., exposes three undertracks that we have modeled as isolated tectonic regimes showing the development of fold-thrust ramp systems induced by the dinosaur’s feet. The faulted and folded sequence is comparable to crustal-scale tectonics associated with plate tectonics and foreland fold-thrust belts. A structural analysis of the dinosaur tracks shows the timing and direction of the forces exercised on the substrate by the animal’s foot during the stride. Based on the structural analysis, we establish a scenario for foot movements and weight distribution in the feet. During …

Temporal And Spatial Variability In Dune Reactivation Across The Nebraska Sand Hills, Usa, Rebecca L. Schmeisser Mckean, Ronald J. Goble, Joseph B. Mason, James Swinehart, David B. Loope

David B. Loope

The Nebraska Sand Hills is a stabilized dune field on the Great Plains of North America. Although it is well known that this dune field, like several others on the Great Plains, last experienced widespread activity during the Medieval Climatic Anomaly (MCA, ~AD 900–1300), spatial variation in the timing and nature of drought development is poorly constrained. To elucidate spatial trends in dune reactivation, samples potentially representing MCA activity across the Sand Hills were collected and dated using optically stimulated luminescence (OSL). Ages from the older part of the MCA were obtained from eolian sediments in the northwestern Sand Hills, …

Large Wind Shift On The Great Plains During The Medieval Warm Period, Venkataramana Sridhar, David B. Loope, James B. Swinehart, Joseph A. Mason, Robert J. Oglesby, Clinton M. Rowe

David B. Loope

Spring-summer winds from the south move moist air from the Gulf of Mexico to the Great Plains. Rainfall in the growing season sustains prairie grasses that keep large dunes in the Nebraska Sand Hills immobile. Longitudinal dunes built during the Medieval Warm Period (800 to 1000 years before the present) record the last major period of sand mobility. These dunes are oriented NW-SE and are composed of cross-strata with bipolar dip directions. The trend and structure of the dunes record a drought that was initiated and sustained by a historically unprecedented shift of spring-summer atmospheric circulation over the Plains: Moist …

Geochemical Evidence For An Eolian Sand Dam Across The North And South Platte Rivers In Nebraska, Daniel R. Muhs, James B. Swinehart, David B. Loope, Josh Been, Shannon A. Mahan, Charles A. Bush

David B. Loope

Geochemical and geomorphic data from dune fields in southwestern Nebraska provide new evidence that the Nebraska Sand Hills once migrated across the North and South Platte rivers and dammed the largest tributary system to the Missouri River. The Lincoln County and Imperial dune fields, which lie downwind of the South Platte River, have compositions intermediate between the Nebraska Sand Hills (quartz-rich) and northeastern Colorado dunes (K-feldspar-rich). The most likely explanation for the intermediate composition is that the Lincoln County and Imperial dunes are derived in part from the Nebraska Sand Hills and in part from the South Platte River. The …

Lethal Sandslides From Eolian Dunes, David B. Loope, Joseph A. Mason, Lowell Dingus

David B. Loope

Fossil vertebrates entombed within the Upper Cretaceous Djadokhta Formation of southern Mongolia bear testimony to a heretofore unknown geologic phenomenon: mass wasting of eolian dunes during heavy rainstorms. Evaporation of shallow-penetrating rainwater led to progressive calcite accumulation in a thin layer of sand about 0.5 m below the surface of dune lee slopes. During rare heavy rainstorms, a perched water table developed at the top of calcitic zones. Positive pore water pressure led to translational slides and fast-moving sediment gravity flows that overwhelmed animals on the lee slopes of large dunes and in interdune areas.

Deposition, Deflation And Diagenesis Of Upper Paleozoic Eolian Sediments Canyonlands National Park, Utah, David Loope

David B. Loope

No abstract provided.

The Geology Of Ukhaa Tolgod (Djadokhta Formation, Upper Cretaceous, Nemegt Basin, Mongolia), Lowell Dingus, David B. Loope, Demberlyin Dashzeveg, Carl C. Swisher Iii, Chuluun Minjin, Michael J. Novacek, Mark A. Norell

David B. Loope

The lithostratigrahy and sedimentology of the fossiliferous Upper Cretaceous strata exposed in the Gobi Desert of Mongolia at Ukhaa Tolgod are described and mapped on aerial photos. Topographic features are also mapped by plane table and alidade. Five lithologic and sedimentologic facies are described: E-1, distinctly cross-stratified sandstone with fine structure, interpreted to represent eolian dune deposits; E-2, vaguely bedded sandstone with cross-stratified concretionary sheets, interpreted to represent eolian dune deposits modified by diagenetic formation of slope-parallel concretionary sheets of pedogenic calcite; S, structureless sandstone lacking concretions or cross-strata, interpreted to represent sandslide deposits generated by mass wasting along the …

Scope And Mechanistic Analysis For Chemoselective Hydrogenolysis Of Carbonyl Compounds Catalyzed By A Cationic Ruthenium Hydride Complex With A Tunable Phenol Ligand, Nishantha Kumara Kalutharage, Chae S. Yi

Chemistry Faculty Research and Publications

A cationic ruthenium hydride complex, [(C₆H₆)(PCy₃)(CO)RuH]⁺BF₄^– (1), with a phenol ligand was found to exhibit high catalytic activity for the hydrogenolysis of carbonyl compounds to yield the corresponding aliphatic products. The catalytic method showed exceptionally high chemoselectivity toward the carbonyl reduction over alkene hydrogenation. Kinetic and spectroscopic studies revealed a strong electronic influence of the phenol ligand on the catalyst activity. The Hammett plot of the hydrogenolysis of 4-methoxyacetophenone displayed two opposite linear slopes for the catalytic system 1/p-X-C₆H₄OH (ρ = …

Retrieval Of Aerosol Microphysical Properties From Aeronet Photopolarimetric Measurements, Xiaoguang Xu

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Atmospheric aerosols play an important role in earth climate by scattering and absorbing solar and terrestrial radiation, and indirectly through altering the cloud formation, life- time, and radiative properties. However, accurate quantification of these effects is in no small part hindered by our limited knowledge about the particle size distribution (PSD) and refractive index, the aerosol microphysical properties essentially pertain to aerosol optical and cloud-forming properties. The research goal of this thesis is to obtain the aerosol microphysical properties of both fine and coarse modes from the polarimetric solar radiation measured by the SunPhotometer of the Aerosol Robotic Network (AERONET). …

Ecology And Morphology Of The Late Miocene Musk Deer, Longirostromeryx Wellsi (Artiodactyla: Moschidae: Blastomerycinae), Katheryn Y. C. Chen

Department of Earth and Atmospheric Sciences: Dissertations, Theses, and Student Research

Longirostromeryx wellsi, one of the latest surviving members of the extinct clade Blastomerycinae (Artiodactyla: Moschidae), possesses highly derived craniodental morphology that deviates from typical musk deer form. Previous work suggests that the unique anatomy of L. wellsi represents adaptations for occupying open savannas. To test this hypothesis I conduct principal components analysis on five postcranial bones of L. wellsi, comparing them to that of several extant ruminant artiodactyls, which are divided among seven habitat categories. These elements are also compared with the postcrania of other blastomerycines. These analyses indicate that L. wellsi anatomy is most similar to that of other …

Haep: Hospital Assignment For Emergency Patients In A Big City, Peng Liu, Biao Xu, Zhen Jiang, Jie Wu

Computer Science Faculty Publications

No abstract provided.

Designing Novel 1,2,3- And 1,2,4-Triazoles For Coordination Complexes And Frameworks, Brianna Celiese Hughes

Doctoral Dissertations

Triazoles are a versatile ligand that forms a variety of compounds and extended materials within the field of coordination chemistry. The reaction of triazoles with metals leads to the synthesis of homoleptic complexes, coordination polymers and metal-organic frameworks (MOFs). These triazole compounds and materials have been employed for a variety of applications in chemistry ranging from nanomaterials to anion recognition.

The synthesis of tris(1,2,3-triazolyl)borate completed and complemented the initial research began by Trofimenko in 1966. This ligand was used in metal reactions and found to form both homoleptic complexes and coordination polymers. The connectivity of the tris(1,2,3-triazolyl)borate varied dependent on …

Versatile Three-Phase Power Electronics Converter Based Real-Time Load Emulators, Jing Wang

Doctoral Dissertations

This dissertation includes the methodology, implementation, validation, as well as real-time modeling of a load emulator for a reconfigurable grid emulation platform of hardware test-bed (HTB). This test-bed was proposed by Center of Ultra-wide-area Resilient Electric Energy Transmission Network (CURENT) at the University of Tennessee, at Knoxville in 2011, to address the transmission level system challenges posed by contemporary fast changing energy technologies.

Detailed HTB introduction, including design concept, fundamental units and hardware construction, is elaborated. In the development, current controlled three-phase power electronics converter based emulator unit is adopted to create desired power system loading conditions.

In the application, …

Engineering Photosystem I Complexes For Use In Bio-Hybrid Dye-Sensitized Solar Cells, Richard Franklin Simmerman

Doctoral Dissertations

Increasing global population, growing per capita energy needs, diminishing fossil fuels, and climate change collectively will require new, innovative, and sustainable alternatives to meet the world’s growing energy needs. One of the most promising yet simple approaches are dye-sensitized solar cells (DSSCs). However, conventional DSSCs use semi-conductor anodes sensitized with complex synthetic organometallic dyes. Most dyes utilize ruthenium complexes to absorb photons, which upon excitation, inject electrons into the anode, while holes migrate to the cathode via liquid electrolyte. However, these dyes are expensive, difficult to make, and resource-limited. This dissertation focuses on replacing synthetic dyes with the naturally occurring, …

Measurements Of Methyl Radicals And Temperatures By Using Coherent Microwave Rayleigh Scattering From Resonance Enhanced Multiphoton Ionization, Yue Wu

Doctoral Dissertations

This thesis includes two main parts: (I) The CH₃[methyl radical] detection in methane/air flames and (II) the rotational temperature measurement of O₂[molecular oxygen] in a variety of environments by using coherent microwave Rayleigh scattering from resonance enhanced multiphoton ionization (Radar REMPI).

In first the part, from Chapter I to Chapter III, the methyl radical detection and quantitative measurements have been conducted in hydrocarbon flame with one-dimensional and two-dimensional spatial-resolved concentration distribution. Due to the proximity of the argon resonance state (4+1 REMPI by 332.5 nm) with the CH₃ state (2+1 REMPI by 333.6 nm), in …

Examination Of Banded Iron Formation Through Petrographic, Geochemical And Iron Isotope Analyses, Melissa Margaret Hage

Doctoral Dissertations

Banded iron formation (BIF) has the potential to preserve geochemical signatures critical to interpretation of early Earth because: (1) it is found within the Precambrian when fundamental changes in Earth’s physical, biological and chemical evolution occurred, and (2) it may preserve a record of the depositional environment. Rare earth elements (REE) are useful for investigating BIF because they have characteristic features. One goal of this study was to evaluate the calculation of certain REE ratios to determine if the calculation affected the interpretation. It was concluded that the method for calculating certain ratios may affect the interpretation of redox conditions …

Developing An Optimal Model For Infant Home Visitation, Isaac Atuahene

Doctoral Dissertations

The United States, Great Britain, Denmark, Canada and many other countries have accepted home visitation (HV) as a promising strategy for interventions for infants after births and for their mothers. Prior HV studies have focused on theoretical foundations, evaluations of programs, cost/benefit analysis and cost estimation by using hospital/payer/insurance data to prove its effectiveness and high cost. As governments and private organizations continue to fund HVs, it is an opportune time to develop and formulate operations research (OR) models of HV coverage, quality and cost so they might be used in program implementation as done for adult home healthcare (HHC) …

Evaluating The Effects Of Standardized Patient Care Pathways On Clinical Outcomes, Anna V. Romanova

Doctoral Dissertations

The main focus of this study is to create a standardized approach to evaluating the impact of the patient care pathways across all major disease categories and key outcome measures in a hospital setting when randomized clinical trials are not feasible. Toward this goal I identify statistical methods, control factors, and adjustments that can correct for potential confounding in observational studies. I investigate the efficiency of existing bias correction methods under varying conditions of imbalanced samples through a Monte Carlo simulation. The simulation results are then utilized in a case study for one of the largest primary diagnosis areas, chronic …

Evidence Of Late Quaternary Fires From Charcoal And Siliceous Aggregates In Lake Sediments In The Eastern U.S.A., Joanne P. Ballard

Doctoral Dissertations

The late-glacial transition to the Holocene, 15,000–11,600 cal yr BP, is an enigmatic period of dynamic global changes and a major extinction event in North America. Fire is an agent of disturbance that transforms the environment physically and chemically, and affects plant community composition. To improve understanding of the linkages between fire, vegetation, and climate over the late glacial and Holocene in the eastern U.S., I analyzed lake-sediment cores for charcoal and indicators of wood ash, and compared results to existing pollen records. A new microscopic charcoal record from Anderson Pond, Tennessee revealed high fire activity from 23,000–15,000 cal yr …

On The Spin Evolution Of Isolated Pulsars, Oliver Quinn Hamil

Doctoral Dissertations

Neutron stars are the remnants of supernova explosions, and harbor the densest matter found in the universe. Because of their extreme physical characteristics, neutron stars make superb laboratories from which to study the nature of matter under conditions of extreme density that are not reproducible on Earth. The understanding of QCD matter is of fundamental importance to modern physics, and neutron stars provide a means of probing into the cold, dense region of the QCD phase diagram.

Isolated pulsars are rotating neutron stars that emit beams of electromagnetic radiation into space which appear like lighthouses to observers on Earth. Observations …

Timing And Extent Of The Little Ice Age Glacial Advances In The Eastern Tian Shan, China, Yanan Li

Doctoral Dissertations

Located in Central Asia, one of the most continental regions on Earth, the Tian Shan’s glaciers contribute critical fresh water to populated areas in the lowland. These glaciers are sensitive to climate change, and knowledge of contemporary glaciers and their changes in the past is of critical importance for sustainable development in this region. Constraining glacial fluctuations in recent centuries will fill a gap in numerical constraints on glacial history and paleoclimate information, and provide important evidence on the spatio-temporal changes of the climate systems in the Tian Shan. This doctoral dissertation investigates the timing and extent of Little Ice …

Nanoscaled Cellulose And Its Carbonaceous Material: Application And Local Structure Investigation, Yujie Meng

Doctoral Dissertations

In this dissertation, cellulose nanocrystals three-dimensional morphology, size distribution, and the crystal structure were statistically and quantitatively investigated. Lognormal distribution was identified as the most likely for cellulose nanocrystals’ size distribution. Height and width dimensions were shown to decrease toward the ends from the midpoint of individual CNCs, implying a spindle-like shape. XRD analysis of crystallite size accompanied with TEM and AFM measurements revealed that the cross-sectional dimensions of individual switchgrass CNC were either rectangular or elliptical shape, with an approximately 3~5 nm [nanometer] lateral element length range. A sponge-like carbon aerogel from microfibril cellulose with high porosity, ultra-low density, …

Synthesis, Characterization And Evaluation Of Lectin-Binding Properties Of 1,2-Cis-Glycosides, Bo Meng

Doctoral Dissertations

This dissertation presents a state-of-the-art research of 1,2-cis-glycosides, including synthetic methodology development, combinatorial total synthesis of galactoside ligands, construction of glycomicroarray surfaces, and quantitative evaluation of carbohydrate–lectin binding properties.

In Chapter 1, as a general introduction, various strategies that have been developed for the stereoselective construction of 1,2-cis-O-glycosidic bond are reviewed. 1,2-cis-O-Glycoside structural units are ubiquitous in nature, and they are extensively involved in numerous biological activities. The systematic identification and evaluation of the roles of carbohydrates usually relies on practical synthetic approaches to afford pure carbohydrates in considerable quantities. …