Physical Sciences and Mathematics Commons^™

Radiocarbon Dating Late Quaternary Loess Deposits Using Small Terrestrial Gastropod Shells, Jeffrey S. Pigati, John Mcgeehin, Daniel R. Muhs, E. Arthur Bettis Iii

United States Geological Survey: Staff Publications

No abstract provided.

The Malthusian–Darwinian Dynamic And The Trajectory Of Civilization, Jeffrey C. Nekola, Craig D. Allen, James H. Brown, Joseph R. Burger, Ana D. Davidson, Trevor S. Fristoe, Marcus J. Hamilton, Sean T. Hammond, Astrid Kodric-Brown, Norman Mercado-Silva, Jordan G. Okie

United States Geological Survey: Staff Publications

Two interacting forces influence all populations: the Malthusian dynamic of exponential growth until resource limits are reached, and the Darwinian dynamic of innovation and adaptation to circumvent these limits through biological and/or cultural evolution. The specific manifestations of these forces in modern human society provide an important context for determining how humans can establish a sustainable relationship with the finite Earth.

Performance Of Human Fecal Anaerobe-Associated Pcr-Based Assays In A Multi-Laboratory Method Evaluation Study, Blythe A. Layton, Yiping Cao, Darcy L. Ebentier, Kaitlyn Hanley, Elisenda Balleste, Joao Brandao, Muruleedhara Byappanahalli, Reagan Converse, Andreas H. Farnleitner, Jennifer Gentry-Shields, Maribeth L. Gidley, Michele Gourmelon, Chang Soo Lee, Jiyoung Lee, Solen Lozach, Tania Madi, Wim G. Meijer, Rachel Noble, Lindsay Peed, Georg H. Reischer, Raquel Rodrigues, Joan B. Rose, Alexander Schriewer, Chris Sinigalliano, Sangeetha Srinivasan, Jill Stewart, Laurie C. Van De Werfhorst, Dan Wang, Richard Whitman, Stefan Wuertz, Jenny Jay, Patricia A. Holden, Alexandria B. Boehm, Orin Shanks, John F. Griffith

United States Geological Survey: Staff Publications

A number of PCR-based methods for detecting human fecal material in environmental waters have been developed over the past decade, but these methods have rarely received independent comparative testing in large multi-laboratory studies. Here, we evaluated ten of these methods (BacH, BacHum-UCD, Bacteroides thetaiotaomicron (BtH), BsteriF1, gyrB, HF183 endpoint, HF183 SYBR, HF183 Taqman^®, HumM2, and Methanobrevibacter smithii nifH (Mnif)) using 64 blind samples prepared in one laboratory. The blind samples contained either one or two fecal sources from human, wastewater or non-human sources. The assay results were assessed for presence/absence of the human markers and also quantitatively while …

A Review Of Environmental Impacts Of Salts From Produced Waters On Aquatic Resources, Aida M. Farag, David D. Harper

United States Geological Survey: Staff Publications

Salts are frequently amajor constituent ofwastewaters produced during oil and gas production. These produced waters or brines must be treated and/or disposed and provide a daily challenge for operators and resourcemanagers. Some elements of salts are regulated with water quality criteria established for the protection of aquatic wildlife, e.g. chloride (Cl⁻), which has an acute standard of 860 mg/L and a chronic standard of 230 mg/L. However, data for establishing such standards has only recently been studied for other components of produced water, such as bicarbonate (HCO3 ⁻), which has acute median lethal concentrations (LC50s) ranging from …

Comparative Embryotoxicity Of A Pentabrominated Diphenyl Ether Mixture To Common Terns (Sterna Hirundo) And American Kestrels (Falco Sparverius), Barnett A. Rattner, Rebecca S. Lazarus, Gary H. Heinz, Natalie K. Karouna-Renier, Sandra L. Schultz, Robert C. Hale

United States Geological Survey: Staff Publications

Concentrations of polybrominated diphenyl ethers (PBDEs) in Forster’s tern (Sterna forsteri) eggs from San Francisco Bay have been reported to range up to 63 µg g^-1 lipid weight. This value exceeds the lowest-observed-adverse-effect level (1.8 µg g^-1 egg wet weight; ~32 µg g^-1 lipid weight) reported in an embryotoxicity study with American kestrels (Falco sparverius). As a surrogate for Forster’s terns, common tern (Sterna hirundo) eggs were treated by air cell injection with corn oil vehicle (control) or a commercial penta-BDE formulation (DE-71) at nominal concentrations of 0.2, 2, and 20 µg g …

Scalar Polarization Operator In A Superfluid Medium, Sajib Kumar Barman

Open Access Theses & Dissertations

A QCD-inspired effective theory of fermions is considered to study superfluidity. We calculate the quark propagator in a theory with fermion-fermion condensate at finite density. In this theory color degrees of freedom are absent and the quark-quark interaction is modeled through a Yukawa interaction term. Since the diquark condensate is neutral, the system is a superfluid. To study the response of this superfluid to the scalar field propagation, we find the scalar polarization operator of the system.

Integrated Geological And Geophysical Studies Of The Indio Mountains And Hueco Bolson, West Texas, Pawan Budhathoki

Open Access Theses & Dissertations

This Dissertation consists of two different projects. The first project describes the results of an outcrop based sequence stratigraphic study of the Albian Cox Sandstone in the Indio Mountains of west Texas. The depositional environment of the Cox Sandstone ranges from shallow marine to the coastal plain deposited in four sequences where sequence 1 and sequence 2 consists of transgressive system tracts (TST) followed by highstand system tracts (HST). The highstand system tract (HST) is missing in sequence 3 and the transgressive systems tract is missing in sequence 4. The Cox changes in thickness from 320 m in the northern …

Lead And Associated Heavy Metal Distribution In El Paso, Texas, Ali Ragab Elkekli

Open Access Theses & Dissertations

Contamination by lead and other heavy metals is one of the most important environmental concerns of today, locally and globally. This issue has led scientists and researchers to study the effect of heavy metals and their distribution in the environment. The aim of the present research is to document the concentration and geographic distribution of heavy metals in El Paso.

The selected heavy metals in the El Paso soil are lead, cadmium, chromium, zinc, antimony and copper. The soil sample for the study was collected during a previous community lead study (RO1 ESO11367; 2001-2006). 500 superficial soils samples were collected …

Urban Impact Of Dissolved Metals In The Paso Del Norte Segment Of The Rio Grande, Sumayeh Ahmad Freiwan

Open Access Theses & Dissertations

The Paso del Norte segment of the Rio Grande experiences two seasons per year; the (wet) irrigation season and the (dry) non-irrigation season. The goal of this study was to improve the understanding of occurrence and contribution of dissolved metals in this region during the non-irrigation season. The objectives of this study were to (1) evaluate the impact of anthropogenic sources of metals on the Rio Grande water quality during the non-irrigation season, and (2) estimate the metal loads carried by the flow to the downstream region of El Paso. In order to evaluate the surface water quality of the …

Reduced-Order Modeling Using Orthogonal And Bi-Orthogonal Wavelet Transforms, Miguel Hernandez Iv

Open Access Theses & Dissertations

It is well known that model reduction methods borrow techniques typically found in data compression, and current state-of-the-art techniques for data compression are based on the wavelet transform. Given these facts, it is surprising that model reduction using wavelets has not received much attention and has not been adequately addressed in the literature. This research seeks to determine if wavelets can be used for model reduction and if wavelet model reduction is a viable alternative to existing model reduction methods.

In this work we propose a novel method for model reduction using wavelets. Specifically, we introduce techniques for deriving wavelet …

Toward New Data And Information Management Solutions For Data-Intensive Ecological Research, Christine Marie Laney

Open Access Theses & Dissertations

Ecosystem health is deteriorating in many parts of the world due to direct and indirect anthropogenic pressures. Generating accurate, useful, and impactful models of past, current, and future states of ecosystem structure and function is a complex endeavor that often requires vast amounts of data from multiple sources and knowledge from collaborating researchers. Ecological data collection has improved rapidly over the past few decades due to the development, innovation, and large scale deployment of automated sensors, which are capable of measuring a gamut of ecosystem properties over broad spatiotemporal scales. Although complex ecosystem models and analyses are increasingly parameterized with …

Crystal Structure, Phase, And Optical Properties Of Yttrium-Doped Hafnium Oxide Nanocrystalline Thin Films, Alejandro Ortega

Open Access Theses & Dissertations

Yttrium-doped hafnium oxide (YDH) nanocrystalline films were produced by sputter-deposition at various substrate times and temperatures, to produce YDH films in a wide range of thicknesses, dYDH∼25 to 1100 nm. The deposition was made onto optical grade quartz and sapphire substrates. Samples deposited on sapphire were subject to post-deposition annealing (PDA) at various times (3-24 hr) and temperatures (1100 - 1500 °C). The effect of d[special characters omitted]YDH on the crystal structure, surface/interface morphology and optical properties of YDH films was investigated. X-ray diffraction analyses revealed the formation of monoclinic phase for relatively thin films (<150nm). The evolution towards stabilized cubic phase with increasing dYDH [special characters omitted]is observed. The scanning electron microscopy results indicate the dense, columnar structure of YDH films as a function of dYDH. Spectrophotometry analyses indicate that the grown YDH films are transparent and exhibit interference fringes. The band gap was found to be ∼ 5.60 eV for monoclinic YDH films while distinct separation and an increase in band gap to 6.03 eV is evident with increasing dYDH and formation cubic YDH films. The PDA films band gaps were found to be between 5.31 and 5.72 eV, all of which exhibit secondary gaps. A correlation between growth conditions, annealing, phase evolution, and optical properties of the YDH nanocrystalline thin films is established.

Refining Molecular Approaches For Bacterial Source Tracking (Bst) In Texas, Joy Truesdale

Open Access Theses & Dissertations

Bacterial source tracking (BST) is a new science that aids in identifying sources of human and animal fecal contamination of environmental water. There are currently two approaches used in BST, library-dependent and library-independent methods. The fecal bacterium E. coli is often used in library dependent methods because it indicates fecal contamination, has been used in human health risk assessments, and has water quality regulatory significance. A disadvantage of E. coli library dependent BST methods is that identification libraries of E. coli isolated from known fecal sources are needed to identify the sources of E. coli isolated from water samples. Further, …

A Block Operator Splitting Method For Heterogeneous Multiscale Poroelasticity, Paul M. Delgado

Open Access Theses & Dissertations

Traditional models of poroelastic deformation in porous media assume relatively homogeneous material properties such that macroscopic constitutive relations lead to accurate results. Many realistic applications involve heterogeneous material properties whose oscillatory nature require multiscale methods to balance accuracy and efficiency in computation.

The current study develops a multiscale method for poroelastic deformation based on a fixed point iteration based operator splitting method and a heterogeneous multiscale method using finite volume and direct stiffness methods. To characterize the convergence

of the operator splitting method, we use a numerical root finding algorithm to determine a threshold surface in a non-dimensional parameter space …

Principal Differential Analysis: Incorporating Covariates Using Kernel Smoothers, Christopher Alfred Dodoo

Open Access Theses & Dissertations

Principal Differential Analysis is a statistical technique which suggests that a given set of functional data curves can be annihilated completely when an estimated linear differential

operator (LDO) is applied (Coddington & Levinson). The novelty of residuals as forcing functions is introduced in PDA.

This thesis builds on PDA with covariates by Jin et al, 2012 by dropping the assumption that the coefficients of the linear differential operator are a product of a function in t and v; the equivalent kernel is used to estimate the coefficient functions at target values. Incorporating covariates with kernel smoothers leads to two …

A Case Study Towards Verification Of The Utility Of Analytical Models In Selecting Checkpoint Intervals, Michael Joseph Harney

Open Access Theses & Dissertations

As high performance computing (HPC) systems grow larger, with increasing numbers of components, failures become more common. Codes that utilize large numbers of nodes and run for long periods of time must take such failures into account and adopt fault tolerance mechanisms to avoid loss of computation and, thus, system utilization. One of those mechanisms is checkpoint/restart. Although analytical models exist to guide users in the selection of an appropriate checkpoint interval, these models are based on assumptions that may not always be true. This thesis examines some of these assumptions, in particular, the consistency of parameters like Mean Time …

Deprivation And Hispanic Health Paradox: Neighborhood Effects On Children's Wheezing In El Paso, Texas, Young-An Kim

Open Access Theses & Dissertations

This study examines the impact of hypothetical health determinants - including objective and relative economic deprivation, as well as foreign-born composition -at the neighborhood-level on respiratory wheezing among Hispanic children in El Paso, Texas while accounting for individual-level covariates based on hierarchical logistic modeling (HLM). Due to El Paso's majority Latino/a population, focus is placed on the so-called "Hispanic health paradox" through analysis of the impact of neighborhood foreign-born composition on Hispanic children's wheezing. Neighborhood-level variables at the census tract-level are derived from US Census data. The percent of families in poverty and the GINI coefficient for income (income inequality) …

Optimization Of Biomass Logistics System Using Genetic Algorithm And Particle Swarm Optimization For Biofuel Production, Ethel Regina Martinez-Schabez

Open Access Theses & Dissertations

As time goes by, Renewable Energy keeps proving to be an important and potential replacement for fossil fuels. All the different types of Renewable Energy offer a relief to the environmental aftermaths of the prolonged reliance on fossil fuel energy. Bioenergy is one of the types of Renewable Energy that can help by minimizing the emissions of fossil fuels. The Energy Independence and Security Act mandates the use of 21 billion gallons of advanced biofuels including 16 billion gallons of cellulosic biofuels by the year 2022. Biomass and Biofuels can clearly become a significant aid to sustainably supply energy in …

Modeling Visibility In The El Paso Del Norte (Pdn) Region, Richard Medina Calderon

Open Access Theses & Dissertations

Poor visibility is a subject of growing public concern throughout the U.S, and an active area of research. Its societal impacts on air quality, aviation transport and traffic are significant. Aerosols play a fundamental role in the attenuation of solar radiation, and also affect visibility. The scattering and extinction coefficients of aerosol particles in the Paso del Norte Region have been calculated using the T- matrix model in conjunction with a laser particle counter. Inter-comparison of the model's results of the scattering and absorption coefficients against the corresponding data from a Photoacustic extinctiometer instrument (which measures in-situ absorption and scattering …

Carbon Emissions From Soil Respiration In The Northern Chihuahuan Desert Shrubland, Anna Cristina Ortiz

Open Access Theses & Dissertations

The United States Department of Agriculture's Jornada Experimental Range (JER), is located in the northern Chihuahuan Desert in southern New Mexico and historically functioned as an experimental rangeland for cattle grazing. Historical grazing in the US Southwest has been identified as a leading, but not the sole, factor that has led to the conversion of pristine grasslands to shrublands, such has been the case on the JER. The estimated increased variability in precipitation intensity and frequency that is predicted to occur with climate warming will likely affect ecosystem responses from ecological processes including primary productivity, microbial decomposition, and thus respiration. …

Environmental Education Through The Lens Of Diverse Elementary School Students In The United States: A Phenomenographic Study, Brissa Yazmin Quiroz

Open Access Theses & Dissertations

Global environmental change is occurring, putting our planet under pressure. Children need to understand not only why the environment is important, but also their role as citizens of a globalized society and their necessary contribution to solving global problems. Students carry their own perspectives about the environment and education, and these differing perspectives should be a significant topic for environmental education research. Recent research studies have included the conceptualization of nature and the environment through children's eyes; yet, no studies have examined the concept of environmental education through the eyes of diverse children. Minority voices and experiences are not frequently …

Heavy Metal Pollution In The Paso Del Norte Region:Historical Reconstruction And Source Interpretation, Eugenia G. Shekhter

Open Access Theses & Dissertations

A unique and complex situation of heavy metal pollution arose in the El Paso del Norte region, one of the largest and oldest metropolitan areas on the US-Mexican border. This region with its complex topography is home to more than 2.2 million people sharing the same environment. Although many studies have been conducted in the region to identify the sources of environmental contamination, the cumulative history of heavy metal pollution is still incomplete. In order to identify the patterns of heavy metal dispersion and to test the hypothesis that the American Smelting and Refining Company (ASARCO) was a considerable contributor …

Snoop-Forge-Replay Attack On Continuous Verification With Keystrokes, Khandaker Abir Rahman

Doctoral Dissertations

We present a new attack called the snoop-forge-replay attack on the keystroke-based continuous verification systems. We performed the attacks on two levels – 1) feature-level and 2) sample-level.

(1) Feature-level attack targets specific keystroke-based continuous verification method or system. In feature-level attacks, we performed a series of experiments using keystroke data from 50 users who typed approximately 1200 to 2300 keystrokes of free text during three different periods. The experiments consisted of two parts. In the first part, we conducted zero-effort verification experiments with two verifiers ("R" and "S") and obtained Equal Error Rates (EERs) between 10% and 15% under …

Self-Adapting Mac Layer For Wireless Sensor Networks, Mo Sha, Meng Xu, Chenyang Lu, Linh T.X. Phan, Tae-Suk Kim, Taerim Park

All Computer Science and Engineering Research

The integration of wireless sensors with mobile phones is gaining momentum as an enabling platform for numerous emerging applications. These mobile systems face dynamic environments where both application requirements and ambient wireless conditions change frequently. Despite the existence of many MAC protocols however, none can provide optimal performance along multiple dimensions, in particular when the conditions are frequently changing. Instead of pursuing a one-MAC-fit all approach we present a Self-Adapting MAC Layer (SAML) comprising (1) a Reconfigurable MAC Architecture (RMA) that can switch to different MAC protocols at run time and (2) a learning-based MAC Selection Engine that selects the …

Geol 106: Environmental Geology—A Peer Review Of Teaching Project Benchmark Portfolio, Leilani Arthurs

UNL Faculty Course Portfolios

The Peer Review of Teaching (PRT) program provides faculty members the environment, support, structure, and time to carefully think about how they teach a particular course. PRT benchmark portfolios are prepared as a part of this program to assist faculty members in reflecting on and documenting their instructional practices and the potential impact they have on student learning.

This benchmark portfolio targets the Spring 2013 semester of GEOL 106: Environmental Geology. It documents the course objectives that provided the foundation for the instructional approach, the course-level learning goals that defined what students should be able to do by the end …

Geol 440/840: Tectonics—A Peer Review Of Teaching Project Inquiry Portfolio, Caroline M. Burberry

UNL Faculty Course Portfolios

This document is a follow-up document to the Benchmark Portfolio for this course, created in 2012. It details the changes made to the course following the observations from the Benchmark Portfolio and demonstrates that discussion of the metacognitive issues surrounding critical thinking does have some effect on increasing student learning. The document concludes with changes which will be made to the 2014 iteration of the class, to continue this inquiry and improvement process.

Coastal Towns Adapt To Realities Of Climate Change, Christine Woodside

Wrack Lines

The effects of climate change on the rate of sea level rise have hit the streets of every coastal town in Connecticut. The future will bring more waters creeping inland not only on the coast of New England, but around the world.

A Vision For Connecticut Shellfish, Tessa S. Getchis

Wrack Lines

Shellfish play a critical role in the marine ecosystem. Filter-feeeding shellfish such as oysters, clams, scallops, and mussels can improve water quality and clarity.

The Meaning Of Music-Making For Computer Scientists With A Serious Musing-Making Avocation: A Phenomenological Case Study, Varda Shaked

Educational Studies Dissertations

This study explores the meaning of music-making in the lives of computer scientists who play classical music as their serious avocation. In particular, it investigates their tendencies and capacities to concurrently engage in two such distinct disciplines on a regular basis, by exploring the cognitive, social, and cultural aspects of their concurrent engagement. While current research literature approaches the affinities between mathematicians/scientists and musicians through the presence of mathematical properties of music and through anecdotal evidence involving known persona and their innovations, this study provides a deeper look at the individuals who combine such worlds, in order to better understand …

Applications Of High Throughput (Combinatorial) Methodologies To Electronic, Magnetic, Optical, And Energy-Related Materials, Martin L. Green, Ichiro Takeuchi, Jason R. Hattrick-Simpers

Faculty Publications

High throughput (combinatorial) materials science methodology is a relatively new research paradigm that offers the promise of rapid and efficient materials screening, optimization, and discovery. The paradigm started in the pharmaceutical industry but was rapidly adopted to accelerate materials research in a wide variety of areas. High throughput experiments are characterized by synthesis of a “library” sample that contains the materials variation of interest (typically composition), and rapid and localized measurement schemes that result in massive data sets. Because the data are collected at the same time on the same “library” sample, they can be highly uniform with respect to …