# Physical Sciences and Mathematics Commons™

Articles 1 - 30 of 2427

## Full-Text Articles in Physical Sciences and Mathematics

Dec 2018

#### Controls On Phosphorus Export From An Agricultural Watershed: Amsden Brook, Fort Fairfield, Maine Usa., Gregory J. Mcdonald

##### Electronic Theses and Dissertations

This study explores the sources and mechanisms of phosphorus (P) mobilization during base flow within the Amsden Brook watershed, Fort Fairfield, Maine, USA. Amsden Brook is an agriculturally dominated watershed drained by a spring-fed and perennial first- to second-order stream. We characterized the P concentrations within the watershed to investigate connections between soils, stream sediment, surface water, and groundwater. Waters were monitored monthly during the 2017 snow-free period for temperature, pH, dissolved oxygen, conductivity, soluble reactive P (SRP), total P, strong acid anions, strong base cations, dissolved organic carbon (DOC), Al, Fe, and Mn. Phosphorus speciation within soils and sediment ...

Dec 2018

#### Stream Dynamics In The Headwaters Of Post-Glacial Watershed Systems, Brett Gerard

##### Electronic Theses and Dissertations

This dissertation summarizes research examining watershed processes across Northern New England, with an emphasis on the Central and Coastal regions of Maine. The research presented here focuses on the linkages between watershed geomorphic conditions, climate, and surface flow regimes driving stream channel hydraulic conditions and bed dynamics governing channel geometry. The geologic and human history of the landscape provides the context in which earth surface processes are examined within the dominant physiographic settings in Maine to describe vulnerabilities to climate change. Results are summarized to support the development of sustainability solutions for forecasted watershed management problems by natural resource management ...

#### Syntheses Of A Tin (Iv) Meso-Tetra(4-Pyridyl) Porphyrin Dichloride-Tetrachlorobis (Bipy)2 Ruthenium (Ii) Complex And Studies Of Photophysical Properties Of 1-Nitropyrene, Phillip Sharp

##### Electronic Theses and Dissertations

Development of a photosensitizer that can work in both aerobic and anaerobic environments would increase the robustness of the cancer treatment known as photodynamic therapy. The development of a photosensitizer was first attempted by synthesizing a tin (IV) meso-tetra (4-pyridyl) porphyrin dichloride-tetrachlorobis (Bipy)2 ruthenium (II) complex. The synthesize of the tin porphyrin was done by a method from literature and had a percent error of 31.58 and 37.31 when comparing the theoretical percentages of carbon (55.39) and nitrogen (12.92) meaning that photosensitizer was not synthesized.

The second type of chromophore that was studied was 1-nitropyrene ...

Dec 2018

#### Mercury In Big Cypress Bayou And Caddo Lake Watersheds In Marion And Harrison Counties Texas, Joseph Watkins

##### Electronic Theses and Dissertations

Caddo Lake has been included on the Texas Commission on Environmental Quality 303(d) list for impairment due to mercury (Hg) content since 1996. One of the primary tributaries, Big Cypress Bayou, flows across Eocene-aged rocks and sediments associated with the Wilcox Group; the Wilcox is of interest because it contains lignite coal, which has a direct link to mercury. Previous research has focused on dry deposition from fossil fuel combustion as the primary source of mercury but has not addressed the potential watershed contribution to mercury concentrations in Caddo Lake.

Big Cypress Bayou flows through Harrison and Marion counties ...

# ABSTRACT

Traditional karst surveys require extensive field investigations to completely characterize large areas. They are often time-consuming, requiring up to several years to collect and categorize data. Bias is given to areas that are most easily accessible and false negatives are common. The implementation of geographic information systems (GIS) has aided in the aggregation and standardization of karst data; however, these systems have also been used to develop terrain models that allow the user to remotely delineate sinkholes and other surficial features. The Fort Hood Military Installation is a karst landscape that has been altered significantly for use in military ...

Dec 2018

#### Multispectral Classification Of Gulf Of Maine Surface Waters: Seasonal And Interannual Variability, Brianna M. King

##### Electronic Theses and Dissertations

Bio-optically, surface waters of the northeastern US continental shelf are strongly heterogeneous, exhibiting highly variable distributions in both time and space of suspended sediment, colored dissolved organic matter (CDOM), and phytoplankton concentration and community structure. These render the standard global NASA satellite chlorophyll algorithm suspect. However, spectral signatures of the water are well quantified by the actual satellite-based multispectral reflectance (Rrs) measurements. Here, we use 6 bands of Rrs measurements from 19 years (1998-2016) of monthly composite SeaWiFS and MODIS data to identify the spectral signatures of dominant water types present over the northeast shelf. A merged multivariate clustering approach ...

#### Computational Quantum Chemistry Studies Of The Interactions Of Amino Acids Side Chains With The Guanine Radical Cation., Edward Acheampong

##### Electronic Theses and Dissertations

Guanine is generally accepted as the most easily oxidized DNA base when cells are subjected to ionizing radiation, photoionization or photosensitization. At pH 7, the midpoint reduction potential is on the order of 0.2 – 0.3 V higher than those of the radicals of e.g. tyrosine, tryptophan cysteine and histidine, so that the radical “repair” (or at least, a thermodynamically favorable reaction) involving these amino acids is feasible. Computational quantum studies have been done on tyrosine, tryptophan, cysteine and histidine side chains as they appear in histones. Density functional theory was employed using B3LYP/6-31G+ (d, p) basis ...

Dec 2018

#### Relative Permittivity As A Function Of Co-Solvent And Impedance Spectroscopy For Quantifying Anions In Solution, Yahya Sami Alseiha

##### Electronic Theses and Dissertations

This work measured relative permittivity from 15.0 to 55.0 °C of aqueous solutions containing acetone or tetrahydrofuran using a BI 870 dielectric meter. A cubic polynomial fit resulted in coefficients for calculating permittivity as a function of temperature and mole fraction. Literature values for other co-solvent system resulted in similar polynomial coefficients. Using BI 870, permittivity measurements of ionic solutions were not possible because of high conductivity. A simple method using impedance spectroscopy measured these solutions. Impedance decreases with increasing temperature and decreases with increasing ionic strength. Due to the temperature dependence of impedance, all measurements were at ...

Dec 2018

#### Extraction And Purification Of Biologically Active Metabolites From Rhodococcus Sp. Mtm3w5.2, Mohrah Alenazi

##### Electronic Theses and Dissertations

Rhodococcushas been recognized as a potential antibiotic producer. Recently, a strain of Rhodococcussp. MTM3W5.2 was isolated from a soil sample collected in Morristown, Tennessee and was found to produce an inhibitory compound which is active against other related species. The purpose of this research is to extract, purify and analyze the active metabolite. The compound was extracted from RM broth cultures and purified by preliminary fractionation of crude extract through a Sephadex LH-20 column. Further purification was completed using semi-preparative reversed phase column chromatography. Final purification was obtained using multiple rounds of an analytical C18 HPLC column ...

##### Electronic Theses and Dissertations

An Italian dominating function on a graph $G = (V,E)$ is a function such that $f : V \to \{0,1,2\}$, and for each vertex $v \in V$ for which $f(v) = 0$, we have $\sum_{u\in N(v)}f(u) \geq 2$. The weight of an Italian dominating function is $f(V) = \sum_{v\in V(G)}f(v)$. The minimum weight of all such functions on a graph $G$ is called the Italian domination number of $G$. In this thesis, we will consider Italian domination in various types of products of a graph $G$ with the complete ...

#### A Normal Form For Words In The Temperley-Lieb Algebra And The Artin Braid Group On Three Strands, Jack Hartsell

##### Electronic Theses and Dissertations

The motivation for this thesis is the computer-assisted calculation of the Jones poly- nomial from braid words in the Artin braid group on three strands, denoted B3. The method used for calculation of the Jones polynomial is the original method that was created when the Jones polynomial was first discovered by Vaughan Jones in 1984. This method utilizes the Temperley-Lieb algebra, and in our case the Temperley-Lieb Algebra on three strands, denoted A3, thus generalizations about A3 that assist with the process of calculation are pursued.

#### Performance Assessment Of The Extended Gower Coefficient On Mixed Data With Varying Types Of Functional Data., Obed Koomson

##### Electronic Theses and Dissertations

Clustering is a widely used technique in data mining applications to source, manage, analyze and extract vital information from large amounts of data. Most clustering procedures are limited in their performance when it comes to data with mixed attributes. In recent times, mixed data have evolved to include directional and functional data. In this study, we will give an introduction to clustering with an eye towards the application of the extended Gower coefficient by Hendrickson (2014). We will conduct a simulation study to assess the performance of this coefficient on mixed data whose functional component has strictly-decreasing signal curves and ...

#### Dreadd Targeting Projections From The Nucleus Accumbens To The Ventral Pallidum With Nicotine Self-Administration, Amanda Smith

##### Electronic Theses and Dissertations

Projections from the Nucleus Accumbens (NAc) to the Ventral Pallidum (VP) play a critical role in motivation and reward. Rewards and reward-associated cues are thought to alter this pathway by suppressing GABA release to the VP, however, the role of the NAc to VP pathway has never been investigated with regard to nicotine self-administration. We hypothesized that increasing GABAergic signaling from the NAc to the VP would decrease the reinforcing effects of nicotine. To increase GABA release, CRE dependent DREADD was expressed in the NAc of male rats. Administration of low dose clozapine activated the DREADD receptor and showed a ...

Dec 2018

#### Imidacloprid Persistence, Mobility, And Effect On Ecosystem Function, Joanna Hardin

##### Electronic Theses and Dissertations

Imidacloprid is a neonicotinoid pesticide used to protect against biting and sucking insects. Land managers rely on its systemic properties, however long-term studies investigating imidacloprid effects on ecosystem function are limited. This study investigated imidacloprid applications to Tsuga caroliniana and Tsuga canadensis over time and compared concentrations to measures of ecosystem function including soil respiration, microbial function, and invertebrate density. Results indicate that imidacloprid is persistent (p0.5). Microbial function and invertebrate density were not significantly different between control and treatment locations nor did imidacloprid concentrations correlate with ecosystem functional indicator activity (p>0.05). It is evident that imidacloprid ...

#### Physical And Chemical Controls On Suffosion Development In Gypsic Soil, Culberson County, Texas, Jonah Morris

##### Electronic Theses and Dissertations

In the Gypsum Plain, suffosion processes have encouraged road failure through dissolution and transport of gypsic soils; however, no prior research has been conducted within the Delaware Basin in regard to these processes. These phenomena were evaluated in both field and laboratory settings in order to assess the parameters of suffosion development associated with Ranch to Market (RM) 652 in Culberson County, Texas, where infrastructure extends across Castile and Rustler strata. Field studies simulated surficial ponding in various gypsic soils and correlated suffosion potential with soil composition and thickness. Soluble fractions of gypsic soils were delineated through geochemical analyses, further ...

#### Depositional Environment And Facies Analyses Of The Owl Mountain Province, Fort Hood Military Installation, Bell And Coryell Counties, Texas, Jacob Meinerts

##### Electronic Theses and Dissertations

The Owl Mountain Province is a plateaued, karst landscape located in the eastern section of the Fort Hood Military Installation and is characterized by Lower Cretaceous Fredericksburg Group carbonates. The topography is capped by thick sequences of the Edwards limestone; steep scarps and incised valleys along the edges of the plateaus host inter-fingering outcrops of the Edwards and Comanche Peak limestones, and the lower valleys are covered by alluvial sediments and intermittent outcrops of the Walnut Clay. These formations were deposited to the north and west of the main Edwards trend, and are thought to be part of a series ...

#### An Outcrop Based Study Of The Weches Formation In Sabine County, Texas: Investigating Its Unconventional Resource Potential Through The Study Of Stratigraphy, Sedimentology, Petrology, And Geochemistry, Talban Kantala

##### Electronic Theses and Dissertations

Fresh Weches Formation (Middle Eocene) exposures found in aggregate quarries in Sabine County, Texas, were sampled, measured, and logged with gamma-ray spectrometry (GRS). Sedimentology and petrology characteristics of Weches samples were analyzed through thin section, scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and GRS Th/K ratios analyses. The source rock quality of the Weches was evaluated with geochemical techniques involving total organic carbon (TOC), Rock-Eval pyrolysis, and GRS Th/U ratios.

The Weches, in the study area, is 27.4 meters thick, and delineated into three major stratigraphic facies: an upper marginal marine prodeltaic facies (Therrill Member) comprised of ...

Dec 2018

#### Groundwater Hydrogeolgy And Hydrochemistry Of Karst Springs In The Eastern Peninsula Of Fort Hood Military Installation, William Scribner Welles

##### Electronic Theses and Dissertations

The eastern peninsula of Fort Hood Military Installation is underlain by a complex karst spring network. These springs are a primary water source in a protected habitat for endangered songbirds, which has only recently begun to be fully investigated. These Fredericksburg Group springs express both epigenetic and hypogenetic karst signatures. The study area is part of a paleo reef trend, a hydraulically disconnected segment of the northern section of the Edwards Aquifer. This study utilized standard ion index values, repeated measures, and principal component analyses on the chemical profiles of six perennial springs to classify spring water sources and their ...

Dec 2018

#### Application Of Silicon Nanohair Textured P-N Junctions In A Photovoltaic Device, Michael Small

##### Electronic Theses and Dissertations

The goal of this project is to design and develop a fabrication process for a silicon photovoltaic device which incorporates a nanohair textured p-n junction. The silicon nanowires are etched into a silicon wafer, comprising an epitaxial p-layer on n-substrate, via metal-assisted chemical etching (MACE). The resulting nanowires contain p-n junctions that lie along the length of the vertical nanowires. This construct has the potential to increase the optical bandwidth of a silicon photovoltaic device by allowing a greater amount of short wavelength light to reach the junction. In addition, the MACE method of nanofabrication has the potential for decreasing ...

Topological Properties Of A 3-Rung Möbius Ladder, Rebecca Woods Dec 2018

#### Topological Properties Of A 3-Rung Möbius Ladder, Rebecca Woods

##### Electronic Theses and Dissertations

In this work, we discuss the properties of the 3-rung Möbius ladder on the torus. We also prove ℤ2 is an orientation preserving topological symmetry group of the 3-rung Möbius ladder with sides and rungs distinct, embedded in the torus.

Oct 2018

#### Modern And Paleoecological Perspectives On A Terrestrial-Marine Linkage In The Falkland Islands, Dulcinea V. Groff

##### Electronic Theses and Dissertations

The Falkland Islands are a biodiversity hotspot in the South Atlantic Ocean, with some of the world’s most important populations of seabirds and seals. The impact of climate change on these marine populations and their coastal breeding habitat in the Falklands is unknown. Coastal grasslands of Poa flabellata (tussac grass) form critical breeding habitat for wildlife, but have been heavily degraded by the introduction of livestock in the 17th century. This dissertation investigates the impacts of global change (climate change, grazing) on P. flabellata and its sensitivity to the fecal nutrient subsidies provided by marine wildlife. Chapter 1 ...

#### An Evaluation Of Geotagged Twitter Data During Hurricane Irma Using Sentiment Analysis And Topic Modeling For Disaster Resilience, Ike Robert Vayansky

##### Electronic Theses and Dissertations

Disasters require quick response times, thought-out preparations, overall community, and government support. These efforts will ensure prevention of loss of life and reduce possible damages. The United States has been battered by multiple major hurricanes in the recent years and multiple avenues of disaster response efforts were being tested. Hurricane Irma can be recognized as the most popular hurricane in terms of social media attention. Irma made landfall in Florida as a Category 4 storm and preparation measures taken were intensive thus providing a good measure to evaluate in terms of efficacy. The effectiveness of the response methods utilized are ...

Oct 2018

#### Late Holocene Spit Evolution On Centennial Timescales In The Southeast Delaware Bay, Usa, Ryan Eli Phillip

##### Electronic Theses and Dissertations

The relationship between barrier spit growth and longshore drift is well established. However, the role of storm activity in spit evolution on an intermediate (centennial) timescale is more of a mystery due to a knowledge gap between decadal-scale shoreline processes and millennial-scale stratigraphic data. Recent studies in the northwestern Atlantic basin using ground-penetrating radar (GPR) and optically-stimulated luminescence (OSL) are providing the opportunity to study centennial-scale shoreline evolution and examine similar age storm activity. Cape Henlopen, Delaware exhibits preserved remnants of a long-term northward-growing spit coastline that evolved from a recurved spit complex, to a cuspate spit, to the present-day ...

#### Towards An Efficient, Scalable Stream Query Operator Framework For Representing And Analyzing Continuous Fields, John Whittier

##### Electronic Theses and Dissertations

Advancements in sensor technology have made it less expensive to deploy massive numbers of sensors to observe continuous geographic phenomena at high sample rates and stream live sensor observations. This fact has raised new challenges since sensor streams have pushed the limits of traditional geo-sensor data management technology. Data Stream Engines (DSEs) provide facilities for near real-time processing of streams, however, algorithms supporting representing and analyzing Spatio-Temporal (ST) phenomena are limited.

This dissertation investigates near real-time representation and analysis of continuous ST phenomena, observed by large numbers of mobile, asynchronously sampling sensors, using a DSE and proposes two novel stream ...

Three Examples Of Mondoromy Groups, Alice A. Wise Aug 2018

#### Three Examples Of Mondoromy Groups, Alice A. Wise

##### Electronic Theses and Dissertations

This thesis illustrates the notion of the Monodromy group of a global analytic function through three examples. One is a relatively simple finite example; the others are more complicated infinite cases, one abelian and one non-abelian, which show connections to other parts of mathematics.

#### Retreat Of The Antarctic Ice Sheet In The Southern Ross Embayment From Records At Amundsen And Liv Glaciers, Southern Transantarctic Mountains, Jillian Pelto

##### Electronic Theses and Dissertations

The Antarctic Ice Sheet contains ~58 m of global sea-level equivalent and thus its future behavior under global warming is of pressing concern. Examination of past ice-sheet behavior during periods of warming climate can afford insight useful for predicting future sea-level rise. This study focuses on a major unanswered question - namely, the cause of Antarctic Ice Sheet retreat following the last glaciation. Documenting the timing and nature of this deglaciation is crucial to understand the mechanisms behind ice-sheet behavior. Here, I examine how the marine portions of the ice sheet responded to the major warming that occurred at the end ...

Nitrogen Cycling During A Period Of Environmental Change, Kaizad Patel Aug 2018

#### Nitrogen Cycling During A Period Of Environmental Change, Kaizad Patel

##### Electronic Theses and Dissertations

Natural and anthropogenic disturbances have altered the N cycle on the regional to global scale. Although numerous studies have examined the effects of chronic atmospheric N deposition on ecosystem processes, less is known about intra-annual variability of these processes, or how these responses might be altered under conditions of changing climate. The work described in this dissertation focuses on the effects of a changing chemical and physical climate, particularly terrestrial N processes (a) during Maine’s changing winters, and (b) in response to chronic elevated N additions.

Subnivean winter soil processes were examined at the Dwight B. DeMerritt Forest (DBDF ...

#### Understanding Student Development Of Science Literacy Skills In An Undergraduate Environmental Science Course, Molly Picillo

##### Electronic Theses and Dissertations

Educators are expected to instill a variety of skills in their students that are necessary to be competent citizens of society. One such set of skills, science literacy skills, broadly encompass the ability of an individual to evaluate reliability of data and information and critically analyze and interpret them (Gormally Brickman, Hallar, & Armstrong, 2009). These skills are utilized in everyday decision-making and given their pertinence, there is a need for citizens to be scientifically literate. Thus, educators need tools and assessments to help students develop these skills and analyze their science literacy. The aim of this study was to develop science literacy interventions that could be easily incorporated into college curricula, providing instructors with exemplars of classroom interventions with the intent to improve students’ science literacy skills. Therefore, the broad research question for this investigation was: How do science literacy interventions impact student proficiency in science literacy skills in college general education courses? I measured effectiveness of the interventions using the Test of Science Literacy Skills (TOSLS, Gormally Brickman, & Lutz, 2012) pre- and post-survey scores, as well as student feedback from pre- and post-survey, follow-up interviews. The TOSLS surveys were given as part of a participation grade to students in a general education undergraduate college course (n = 148). A subset of students volunteered to be interviewed regarding specific questions from the TOSLS survey, after both the pre-survey (n = 12) and the post-survey (n = 5), to further investigate student understanding and interpretation. Interventions were designed by modifying previous assignments from earlier years’ offerings of the class and were conducted both during class and outside of class as homework extensions. These interventions were created by evaluating scores and interviews on the TOSLS survey deployed as a pilot study in a previous semester of the undergraduate course. Based on these pilot data, four survey questions encompassing different science literacy skills of particular difficulty were targeted for intervention. The interventions were: (1) An interactive clicker-based lesson involving graph selection methods; (2) Data summits involving graph interpretation and source evaluation; and (3) A role-play after which students discussed sources of bias.

Although the results indicated no statistically significant changes in the average scores between the pre-survey and post-survey (t test, p = 0.82, α = 0.05), interviewed students recalled ...

Biomass Based Monomers For Synthesis Of Renewably Sourced Polymers, Anushka E. Vithanage Aug 2018

#### Biomass Based Monomers For Synthesis Of Renewably Sourced Polymers, Anushka E. Vithanage

##### Electronic Theses and Dissertations

Limited fossil resources have raised research focus on synthesizing novel, sustainable polymers and renewably sourcing existing petroleum based polymers. This work presents the synthesis and ring opening polymerization (ROP) of a new functionalized lactone monomer, methoxy-δ-hexalactone (MDHL), to yield a functionalized polyester (polyMDHL). MDHL can be renewably sourced from hydroxymethylfurfural, a renewable platform chemical. MDHL was synthesized from methyl cyclopentanone-2-carboxylate by a five-step synthesis with a global yield of 23%. ROP of MDHL was conducted with benzyl alcohol initiator, catalyzed by diphenyl phosphate. 1H Nuclear Magnetic Resonance spectroscopy verified polyMDHL chemical structure. Targeting higher molecular weights for polyMDHL by increasing ...

Mechanistic Studies Of Reducible Metal Oxides As Hydrodeoxygenation Catalysts, Akbar Mahdavi Shakib Aug 2018

#### Mechanistic Studies Of Reducible Metal Oxides As Hydrodeoxygenation Catalysts, Akbar Mahdavi Shakib

##### Electronic Theses and Dissertations

Hydrodeoxygenation of phenol to benzene using ruthenium supported titania catalysts strongly varies depending on the support crystal structure and preparation conditions. Here, we performed spectroscopic characterization of titania supports to identify the surface impurities common to commercial and synthesized titania samples using a variety of spectroscopic methods. Sulfate impurities were detected for the commercial anatase samples and a procedure for their elimination was proposed so that inactive catalysts gained reactivity. Surface hydroxyls of different TiO2 samples (anatase, rutile, and pyrogenic) were identified using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments performed on vigorously cleaned surfaces and a facet-specific assignment ...