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Estimating Nitrogen Fixation Rates, Importance, And Short-Term Efficiency In Small, Temperate Reservoirs Using Delta15n Techniques, Bryant Christopher Baker

Graduate Theses and Dissertations

Nitrogen (N2) fixation can give certain species of cyanobacteria a competitive advantage in lake and reservoir phytoplankton. These species of cyanobacteria, along with others that cannot fix N2, can form toxic compounds that impair water quality when present in high concentrations. N2 fixation rates may be substantial in small (< 1.0 km2), temperate reservoirs since these systems experience thermal stratification and often nitrogen (N) limitation throughout a substantial proportion of the year. However, the effects of N2 fixation on N cycling, alleviation of short-term N limitation, and water quality are not well-understood. A mesocosm experiment and ecosystem-scale observational study were conducted to 1) determine the efficiency of N2 fixation under varying N relative to phosphorus (P) supply, 2) examine the effects of N2 fixation on autotrophic biomass accumulation and microcystin production, and 3) measure N2 fixation rates and importance to autotrophic N demand and zooplankton N assimilation. Results of the mesocosm experiment indicated that N2 fixation was increased at low N:P supply under high P. However, N2 fixation was inefficient at alleviating N limitation when fixed N was the primary source of N. Additionally, microcystin production occurred only at high N:P supply when N2 fixation was low, indicating that reducing external N inputs may have a positive effect on water quality. Results of whole-reservoir determination of N2 fixation using seston δ15N natural abundances indicated that N2 fixation rates throughout the warm season were substantial and influenced by water temperature. Annual N2 fixation rates ranged from 2.2 - 6.6 g N m-2 yr-1, and contributed up to 19% of the annual autotrophic N demand. Zooplankton were assimilating fixed N in most of the study reservoirs, representing a possible mechanism of ecosystem fixed N retention. Collectively, these results suggest that N2 fixation plays a substantial role in N cycling in small, temperate reservoirs, but likely cannot alleviate short-term N limitation.

Efficacy Of Rice Insecticide Seed Treatments At Selected Nitrogen Rates For Control Of The Rice Water Weevil, Lissorhoptrus Oryzophilus Kuschel, Mallory Elise Everett

Graduate Theses and Dissertations

Seed-applied insecticides are the standard control method used to prevent rice water weevil (Lissorhoptrus oryzophilus Kuschel) injury to rice (Oryza sativa L.) roots, and often results in greater yields than rice that receives no seed-applied insecticide. Yield increases from seed-applied insecticides often occur even when insect pressure is low and should not cause yield loss. The research objective was to evaluate the effect of urea-nitrogen rate and seed-applied insecticide on number of rice water weevil larvae, nitrogen uptake and rice grain yield. Six trials were conducted at the Pine Tree Research Station (PTRS) and the Rice Research Extension Center (RREC) …

The Effects Of Maternal Information Transmission On Daughters' Responding To A Voluntary Hyperventilation Challenge, Ashley Arehart Knapp

Graduate Theses and Dissertations

Contemporary models of panic etiology would benefit from additional tests of how fear of internal cues is acquired. Drawing from literature suggesting parent-to-child verbal information transmission is one pathway by which fear of external stimuli is learned, the current study is designed to address the effects of this pathway on fearful responding to internal cues (i.e., somatic perturbation produced by a voluntary hyperventilation challenge). Specifically, 53 mothers of adolescent females between the ages of 10 and 14 years were randomly assigned to either share negative or positive information regarding their experience with a voluntary hyperventilation challenge prior to their daughters …

Functionalization Of Silica Surface Using Chan-Lam Coupling, George Appiah Kubi

Electronic Theses and Dissertations

The reaction of base-free Chan-Lam coupling was successfully used for functionalization of surface of mesoporous silica gel. Various aromatic, aliphatic, and heterocyclic compounds were immobilized by a copper-catalyzed reaction of corresponding boronic acids with surface amino groups at mild conditions. Obtained functionalized materials were mesoporous although their surface area decreased after immobilization. The reactivity of some surface functional groups was tested in their characteristic reactions.

Design Of A Light-Weight Low-Volume High Oxygen Storage Density Material, Nicholas Robert Schwartz

Theses and Dissertations

A compact, lightweight, dense and safe method for storing and supplying oxygen remains a large hurdle for closed-circuit self-contained breathing apparatus (SCBA) and respiratory protective equipment. No filter that can protect against airborne chemical, biological, radiological, and nuclear (CBRN) contaminants exists, which presents the need for an isolated oxygen source. Heavy and high maintenance oxygen cylinders are typically used. The most important criteria for a smart and effective CBRN protection device are safety, weight, size, and cost, level of maintenance, ease-of-use and reliability. This study focused on nanomaterials for high capacity gas storage. Nanocapillary arrays composed of anodic aluminum oxide …

High-Dose Interleukin-2 Administration In The Oncology Medical-Surgical Setting – An Innovation To Impact Cost Efficiencies, Clinical Outcomes And The Ideal Patient Experience, Deidre L. Kutzler Rn, Megan L. Derr Rn

Patient Care Services / Nursing

No abstract provided.

Improving Lamb Performance With Sericea Lespedeza And Molybdenum, Mohan Acharya

Graduate Theses and Dissertations

The objective of this research was to find the effect of prolonged feeding of sericea lespedeza (SL) supplemented with sodium molybdate on changes in body weight, serum and liver concentration of trace minerals (TM), hematology, serum biochemistry, and gastrointestinal parasites. Thirty ram lambs (Katahdin and ¾ Katahdin × ¼ Romanov) were weaned; blood, liver, and fecal samples were collected and signs of internal parasitic infection on lambs were recorded. Lambs were supplemented with 900 g of alfalfa (n = 10; CON) or SL (n = 20) based supplement for 103 d. Within the SL group, half of the lambs were …

Analysis Of Environmental Influences On Dressed Stone Decay: A Case Study Of Tafoni Development On A Hewn Djinn Block In Petra, Jordan, Kaelin M. Groom

Graduate Theses and Dissertations

Petra, Jordan captivates tourists and researchers with its dramatic sandstone cliffs, Nabatean, Roman, Byzantine and Roman architecture, and rich cultural heritage. However, increasing tourism in the valley is exacerbating stone degradation and complicating heritage management. This research analyzed environmental influences on dressed stone decay via tafoni development and evaluating cell evolution on an isolated hewn feature, known as Djinn Block X. Resembling other sandstone blocks found in the area, this irregular sandstone monument exhibits faces ranging in size from 2.5m by 3.5m to 3.9m to 4.2m (29m perimeter). Protruding features, incisions along the top, and a large platform attached to …

Habitat Assessment Of Two Narrowly Endemic Plant Species, Ozark Spiderwort (Tradescantia Ozarkana) E. S. Anderson And Woods. And Newton's Larkspur (Delphinium Newtonianum) D. M. Moore, Autumn Lynn Coffey Olsen

Graduate Theses and Dissertations

The threat of biodiversity loss is upon us with the onset of climate change and our ever-demanding needs of the Earth's resources for a rapidly growing human population. Species highly vulnerable to loss are those limited in abundance and distribution, or those with reduced genetic diversity. Efforts to actively conserve a sensitive species require effectual data on the probable causes of their vulnerability. Two species of concern, Delphinium newtonianum and Tradescantia ozarkana, are globally rare endemic vascular plant species found only in the Interior Highlands of North America. In an attempt to understand the causes for their endemism, habitat …

Effects Of Petroleum Distillates On Amphibian Development, Kate Walker

Graduate Theses and Dissertations

Petroleum distillates are widely used as an energy source and the extraction and disposal of these chemicals are done with little consideration of their effects on aquatic environments. Amphibians are considered excellent ecological indicators but little research has examined effects of petroleum distillates on aquatic species. I evaluated the lethal and sublethal effects on larval amphibians with exposure to petroleum distillates associated with various venues of pollution including hydraulic fracturing. I selected three petroleum distillates (kerosene, oil, and unleaded gasoline) that are known to have negative effects on aquatic organisms and are similar to the common constituents of mixtures used …

Stability Of Nano-Encapsulated Rice Bran Derived Bioactive Pentapeptide In Apple Juice, Fatima Mohammed Alessa

Graduate Theses and Dissertations

Cereal grains and their components derived Bioactive compounds such as rice bran can promote health and can be derived from Rice bran contains 12-20 % protein and could be a good source for extracting bioactive peptides. A pentapeptide with a secqunce of amino acids Glu-Gln-Arg-Pro-Arg (EQRPR) has been prepared from heat stablized defatted rice bran (HDRB) and has demonstrated anti-cancer proprerties in-vitro. This bioactive pentapeptide can thus be used as a nutraceutical by incorporating it into a suitable food system. Fruit juces can be vehicles to incorporate this pentapeptide. Fruit juices contribute to about 60% of the consumed beverages in …

Fertilizer Nitrogen Uptake Efficiency In Soft Red Winter Wheat And The Ability Of N-Star To Detect Alkaline Hydrolyzable Nitrogen In Crop Residues, Lana Aubrey Clark

Graduate Theses and Dissertations

Soil testing methods such as the Illinois Soil Nitrogen Test (ISNT) and Direct Steam Distillation (DSD) have been developed which measure alkaline hydrolyzable-N (AH-N) as a means of estimating potentially mineralizable-N. Crop residues play an important role in N cycling. However, the ability of the ISNT and DSD methods to determine AH-N within crop residues is unknown. Therefore, the first objective of this study was to determine the ability of the ISNT and DSD to quantify potentially mineralizable-N within five different crop residues common to Arkansas. Corn (Zea mays L.), soybean (Glycine max, L.), wheat, rice (Oryza sativa, L.), and …

Rape Myths And Consent In College-Aged Southern Students, Amy Leanne Cofer

Graduate Theses and Dissertations

Rape and sexual assault are problematic issues for women on college campuses. Internal and external consent play a role in understanding sexual assault because sexual assault is defined as "nonconsensual sexual activity obtained through force, threats, intoxication, or intimidation." Factors related to understanding consent may include attitudes regarding sexual assault and rape, known as rape myths, which are defined as attitudes and false statements concerning rape that are widely known and accepted, mainly served to justify male sexual aggression towards women. The southeastern United States is known for being religiously and politically conservative, where gender roles are intertwined with a …

Synthesis And Characterization Of Nanocrystals And Their Application For Photodetectors, Ahmad Nusir

Graduate Theses and Dissertations

Room temperature operation is considered one of the essential restrictions in the design of electronic devices. Photodetectors are unable to detect light efficiently at room temperature due to high dark currents. Semiconductor nanocrystals possess unique optical and electrical properties which make them ideal for fabricating uncooled photodetectors. In this project, nanocrystals were synthesized and implemented in devices that detect light at room temperature.

Nanocrystalline I-III-VI2 and II-VI semiconductors (CuInS2 and CdSe) were grown by a wet chemical method, and characterized using: optical absorption, photoluminescence, Raman scattering, and x-ray diffraction. The optical absorption and photoluminescence spectra of the nanocrystals were recorded …

Hope, Faith And Trust: Conversations With Tibetans In Exile, William Lukas Gramlich

Graduate Theses and Dissertations

The goal of Hope, Faith and Trust: Conversations with Tibetans in Exile was to create a documentary to serve as a platform for Tibetan refugees living in India to tell, in their own words, the story of the Tibetan peoples' political struggles since the Chinese government occupied Tibet in the 1950s. To achieve this goal, this project utilized oral-history interviews with Tibetan exiles, gathered as part of the University of Arkansas TEXT Program. The TEXT Program, short for Tibetans in Exile Today, is a study abroad oral-history project in which undergraduate students conduct interviews with Tibetans living in India. The …

Comparing Virus Ultrafiltration Of Bacteriophages With Filtration Of Minute Virus Of Mice, Kent Smith

Graduate Theses and Dissertations

Industrial production of protein therapeutics demand rigorous testing and clearance of viruses. The U.S. Food and Drug Administration dictate the purity of pharmaceuticals with regards to viral contamination. As this testing is time consuming and expensive using mammalian cells and viruses, bacteriophages may provide a faster and cheaper alternative for membrane filtration processes. We used ultrafiltration membranes to filter protein solutions with viruses. Two bacteriophages were tested against membranes with two different pore sizes. These membranes were then tested by inverting the membrane's orientation. Flux measurements and log virus removal data were taken. Flux and log virus removal were seen …

Infrared Energy Harvesting For Optoplasmonics From Nanostructured Metamaterials, Gregory Thomas Forcherio

Graduate Theses and Dissertations

Metamaterials exhibit unique optical resonance characteristics which permit precise engineering of energy pathways within a device. The ability of plasmonic nanostructures to guide electromagnetism offers a platform to reduce global dependence on fossil fuels by harvesting waste heat, which comprises 60% of generated energy around the world. Plasmonic metamaterials were hypothesized to support an exchange of energy between resonance modes, enabling generation of higher energy photons from waste infrared energy. Infrared irradiation of a metamaterial at the Fano coupling lattice resonance was anticipated to re-emit as higher energy visible light at the plasmon resonance. Photonic signals from harvested thermal energy …

Small Mammal Community Associations And Habitat Use At Pea Ridge National Military Park, Benton County, Arkansas, Christopher Reddin

Graduate Theses and Dissertations

Juniperus virginiana L. (Eastern Red Cedar) is a fire-intolerant tree species that has been invading and altering grassland ecosystems throughout the American Great Plains and Midwest. To see how Eastern Red Cedar encroachment affects small mammal communities, we surveyed small mammals using mark-recapture methods in Eastern Red Cedar forest and 5 other habitats common to the Ozark region. Additionally, we compared the microhabitat use of presumed juniper obligate Peromyscus attwateri J.A. Allen (Texas Mouse) and its conspecific P. leucopus Rafinesque (White-Footed Mouse). We ran over 7000 trap-nights and found that the small mammal species composition in Eastern Red Cedar was …

Methane Emissions And Ammonia Volatilization From Drill-Seeded, Delayed-Flood Rice On A Silt-Loam Soil In Arkansas, Christopher Wade Rogers

Graduate Theses and Dissertations

The Environmental Protection Agency (EPA) currently uses a single methane (CH4) emissions factor of 160 kg CH4-C ha-1 for a primary rice (Oryza sativa L.) crop. The emissions factor is based on studies that do not adequately represent current management practices in Arkansas. Another concern is pre-flood fertilizer nitrogen (N) management, as the common N source, urea, is prone to loss via ammonia (NH3) volatilization. Thus, the objective of this research was to investigate trace gas emissions from rice on a silt-loam soil, including CH4 emissions as influenced by nitrogen (N) fertilization (i.e., optimal N and no N) in 2011, …

Effect Of Limit-Fed Co-Product Feedstuffs On Production, Digestion, Fermentation And Rumen Function In Beef Cattle, William Brandon Smith

Graduate Theses and Dissertations

In terms of energy density, the cost of shipping hay is often not justified in yr where adverse conditions limit available forage. Our objective was to determine if co-product feedstuffs could be used to meet the energy demands for cows in late pregnancy. Eighty-six crossbred cows (527 ± 0.8 kg BW) in late gestation were stratified by BW, BCS and age and allocated randomly to 1 of 6 groups held on 2-ha dormant bermudagrass pastures for 68 d. Three groups were offered bermudagrass hay ad libitum (HAY) and three groups were offered 6.4 kg of soybean hulls (LSH) daily and …

Porosity Development Within Lobes To Downslope Ramp Deposits On A Prograding Carbonate Shelf Of The Kinderhookian To Osagean Series In Northwest Arkansas, Elizabeth Marchese

Graduate Theses and Dissertations

Carbonate bodies with lobate geometries form a substantial part of the Osagean (early Mississippian) section in northwest Arkansas. The purpose of this study is to isolate and describe a single lobe from three-dimensional exposures in quarry walls to provide criteria by which lobe and lobe porosity can be recognized in the subsurface. Carbonate sediment generated on the Mississippian Burlington shelf moved southward by gravity flows from the shelf margin to positions on a prograding ramp in Arkansas where overlapping deposits with lobate geometries accumulated. These deposits are recognized in outcrops of the Boone Formation. Stratigraphic units within the Boone are …

Survival, Abundance, And Geographic Distribution Of Temperate-Nesting Canada Geese (Branta Canadensis) In Arkansas, Margaret Eliese Ronke

Graduate Theses and Dissertations

Temperate-nesting Canada geese in Arkansas have grown in abundance and range since reintroduction in the 1980s. The Arkansas Game and Fish Commission uses harvest and other methods to maintain the population at desired levels. However, continued management of temperate-nesting geese requires knowledge of the population's demographics and current range to help establish quantifiable management goals.

To assess the need and effect of changing hunting regulations, survival and recovery rates and abundance were estimated for this population. Annual survival rates of temperate-nesting Canada geese banded and recovered in Arkansas from 2005 to 2011 were estimated using the Burnham joint live-dead recovery …

Production Of A Soybean Meal With High-Protein And Low Anti-Nutritional Factors For Fish Feed, Maria De Las Mercedes Castro

Graduate Theses and Dissertations

Aquaculture is one of the fastest growing areas of the food production system. According to the FAO, its rise is expected to continue through the year 2030 in order to maintain per-capita consumption levels required for the increasing population. Fishmeal--obtained from wild-harvested fish--has been the source of protein for fish feed. However, data indicates that these fish harvests are in decline, which could restrain that growth. The possibility of a shortage of fishmeal prompted the industry to look into possible alternatives. Soybean meal appears as a promising substitute since it is an affordable high quality source of protein. However, the …

Participation In Recreation And Leisure Activities In Long-Term Care Facilities And Health Related Quality Of Life, James Michael Duncan

Graduate Theses and Dissertations

The purpose of this paper was to examine predicted variations in Health Related Quality of Life (HRQoL) among individuals over the age of 65 residing in Long Term Care (LTC) facilities. Variables related to self-care, depression, gender, social support, and leisure activities were examined. Univariate analysis was conducted from data collected from 110 LTC residents from 15 assisted living facilities (ALF) and nursing homes (NH) throughout Arkansas and a standard multiple regression was employed. Linear combinations of independent variables were significantly correlated to variations of HRQoL. More specifically, higher ratings in depression were positively correlated to lower ratings of HRQoL. …

A Tale Of Two Methylation Modifications In Archaeal Rnas, Kunal Chatterjee

Dissertations

In all the three domains of life, most RNAs undergo post transcriptional modifications both on the bases as well as the ribose sugars of the individual ribonucleotides. 2'-O-methylation of ribose sugars and isomerization of Uridines to Pseudouridines are two most predominant modifications in rRNAs and tRNAs across all domains of life. Besides 2'-O-methylation of ribose sugars, methylation of pseudouridine (Ø) at position 54 of tRNA, producing m1Ø, is a hallmark of many archaeal species but the specific methylase involved in the formation of this modification had yet to be characterized. A comparative genomics analysis had previously identified COG1901 (DUF358), part …

Evaluation Of Non-Functionalized Single Walled Carbon Nanotubes Composites For Bone Tissue Engineering, Ashim Gupta

Dissertations

Introduction: Bone defects and non-unions caused by trauma, tumor resection, pathological degeneration, or congenital deformity pose a great challenge in the field of orthopedics. Traditionally, these defects have been repaired by using autografts and allografts. Autografts have set the gold standard for clinical bone repair because of their osteoconductivity, osteoinductivity and osteogenicity. Nevertheless, the application of autografts is limited because of donor availability and donor site morbidity. Allografts have the advantage that the tissues are readily available and can be easily applied, especially when large segments of bone are to be reconstructed. However, their use is also limited by the …

Effect Of Structure In Problem Based Learning On Science Teaching Efficacy Beliefs And Science Content Knowledge Of Elementary Preservice Teachers, Selena K. Sasser

Dissertations

This study examined the effects of differing amounts of structure within the problem based learning instructional model on elementary preservice teachers' science teaching efficacy beliefs, including personal science teaching efficacy and science teaching outcome expectancy, and content knowledge acquisition. This study involved sixty (60) undergraduate elementary preservice teachers enrolled in three sections of elementary science methods classes at a large Midwestern research university. This study used a quasi-experimental nonequivalent design to collect and analyze both quantitative and qualitative data. Participants completed instruments designed to assess science teaching efficacy beliefs, science background, and demographic data. Quantitative data from pre and posttests …

Atomistic Modeling Of Phonon Bandstructure And Transport For Optimal Thermal Management In Nanoscale Devices, Sasi Sekaran Sundaresan

Dissertations

Monte Carlo based statistical approach to solve Boltzmann Transport Equation (BTE) has become a norm to investigate heat transport in semiconductors at sub-micron regime, owing mainly to its ability to characterize realistically sized device geometries qualitatively. One of the primary issues with this technique is that the approach predominantly uses empirically fitted phonon dispersion relations as input to determine the properties of phonons so as to predict the thermal conductivity of specified material geometry. The empirically fitted dispersion relations assume harmonic approximation thereby failing to account for thermal expansion, interaction of lattice waves, effect of strain on spring stiffness, and …

Open Quantum System Dynamics For Describing State Transfer, Nayeli Zuniga-Hansen

Dissertations

In principle a quantum system could be used to simulate another quantum system. The purpose of such a simulation would be to obtain information about problems which are difficult to simulate on a classical computer due to the exponential increase of the Hilbert space with the size of the system, and which cannot be readily measured or controlled in an experiment. A quantum simulator is, however, an open quantum system that will interact with the surrounding environment, which in this case are other particles in the system, and will be implemented using imperfect controls, making it subject to noise. It …

Phylogenetic Revision Of The Genus Arenivaga (Rehn) (Blattodea: Corydiidae), With Descriptions Of New Species, A Key To The Males, And An Investigation Of Its Ecological Niche, Heidi Hopkins

Biology ETDs

The cockroach genus Arenivaga is revised. Forty-eight Arenivaga species are recognized with nine previously known species and 39 described as new including the following: A. pagana sp. n., A. grandiscanyonensis sp. n., A. haringtoni sp. n., A. hopkinsorum sp. n., A. umbratilis sp. n., A. tenax sp. n., A. impensa sp. n., A. trypheros sp. n., A. darwini sp. n., A. nalepae sp. n., A. sequoia sp. n., A. mckittrickae sp. n., A. gaiophanes sp. n., A. belli sp. n., A. estelleae sp. n., A. delicata sp. n., A. mortisvallisensis sp. n., A. milleri sp. n., A. pratchetti sp. n., …