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Articles 1 - 12 of 12
Full-Text Articles in Physical Sciences and Mathematics
Nonlocal Helmholtz Decompositions And Connections To Classical Counterparts, Andrew Haar, Petronela Radu
Nonlocal Helmholtz Decompositions And Connections To Classical Counterparts, Andrew Haar, Petronela Radu
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In recent years nonlocal models have been successfully introduced in a variety of applications, such as dynamic fracture, nonlocal diffusion, flocking, and image processing. Thus, the development of a nonlocal calculus theory, together with the study of nonlocal operators has become the focus of many theoretical investigations. Our work focuses on a Helmholtz decomposition in the nonlocal (integral) framework. In the classical (differential) setting the Helmholtz decomposition states that we can decompose a three dimensional vector field as a sum of an irrotational function and a solenoidal function. We will define new nonlocal gradient and curl operators that allow us …
Remediation Strategies To Reduce Heavy Metal Uptake In Lettuce Grown In Contaminated Urban Soil, Ryley Thomas
Remediation Strategies To Reduce Heavy Metal Uptake In Lettuce Grown In Contaminated Urban Soil, Ryley Thomas
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Urban soils are increasingly used to produce food for local consumption, which requires at the same time management strategies that prevent the plant uptake of potentially present contaminants. This study was conducted to test different soil amendments for their ability to retain lead (Pb) and arsenic (As) within the soil matrix. The analyzed soil was taken from a potential community garden lot near a railroad in Lincoln, NE where elevated concentrations in Pb and As had been detected. Ponderosa pine biochar and spent coffee grounds were used as soil additives because of their documented chemical reactivity towards soil cations or …
Measurements Of Radio Pulse Reception With Stations Of The Ara Experiment Based On The Spicecore Pulser Data Set, Jesse Osborn, Ilya Kravchenko Dr.
Measurements Of Radio Pulse Reception With Stations Of The Ara Experiment Based On The Spicecore Pulser Data Set, Jesse Osborn, Ilya Kravchenko Dr.
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The Askaryan Radio Array Experiment located near the South Pole works to pinpoint specific instances of neutrinos from outside the solar system interacting with nucleons inside the Antarctic ice. Neutrinos are a subatomic particle that has nearly no mass and a net neutral charge. As they are, neutrinos tend not to interact with anything as they travel through space which means they can provide us with information about events occurring far from Earth that might not be easily attained through other methods. Neutrinos are known to be emitted from a myriad of sources, including the Sun, the interaction between cosmic …
Testing A Drone-Based Magnetic Field Surveying System, Erik Jacobson, Irina Filina
Testing A Drone-Based Magnetic Field Surveying System, Erik Jacobson, Irina Filina
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Aeromagnetic surveys are conducted by geoscientists to study subsurface geologic structures, such as faults. This type of survey uses a magnetometer mounted upon an airborne vehicle to collect magnetic field data. Magnetic anomalies are caused by variations in subsurface geology, namely in magnetic properties of subsurface rocks. Jacobson and Filina (2019) reported on the development of a new low cost drone, based magnetic field surveying system by the UNL Geophysics Team. This drone-based magnetic system is capable of collecting high resolution data at low speeds and low altitudes. The current study focuses on testing this system by conducting two flights …
Phosphorus Nmr And Its Application To Metabolomics, Paula Evans, Fatema Bhinderwala, Robert Powers, Martha Morton, Thomas Smith
Phosphorus Nmr And Its Application To Metabolomics, Paula Evans, Fatema Bhinderwala, Robert Powers, Martha Morton, Thomas Smith
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Stable isotopes are routinely employed by NMR metabolomics to highlight specific metabolic processes and to monitor pathway flux. 13C-carbon and 15N-nitrogen labeled nutrients are convenient sources of isotope tracers and are commonly added as supplements to a variety of biological systems ranging from cell cultures to animal models. Unlike 13C and 15N, 31P-phosphourous is a naturally abundant and NMR active isotope that doesn’t require an external supplemental source. To date, 31P NMR has seen limited usage in metabolomics because of a lack of reference spectra, difficulties in sample preparation, and an absence of two-dimensional (2D) NMR experiments. But, 31P NMR …
Management Effects On Soil Quality Of The Geary Soil Series In Thayer County, Nebraska, Aime Nishimwe
Management Effects On Soil Quality Of The Geary Soil Series In Thayer County, Nebraska, Aime Nishimwe
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The CGIAR reports that around 40% of global crop yield variability is explained by climate. While global food consumption is expected to soar in 2050, the impact of climate change accounts for approximately 5% decrease in crop productivity. FAO estimates a 60% increase in global food demand by 2050, with global population reaching 9.8 billions. Sustainable soil management was also noted to boost agricultural food production by 58%. The evaluation of the impact of different management practices on dynamic soil properties was conducted on Geary silty clay loam, 3 to 7 %, eroded soils, which are mainly used for crop …
Impacts Of Human Recreation On Nutrient Availability And Periphyton Abundance On The Niobrara River, Matthew Chen, Jessica Corman, Sydney Kimnach, Kayla Vondracek
Impacts Of Human Recreation On Nutrient Availability And Periphyton Abundance On The Niobrara River, Matthew Chen, Jessica Corman, Sydney Kimnach, Kayla Vondracek
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In freshwater ecosystems, eutrophication can create many problems. Excess nutrients, like nitrogen or phosphorus, promote algal or cyanobacterial growth. This growth also leads to increased organic matter production and decomposition, a process that can reduce oxygen concentration in the water. When this happens, species diversity declines, transparency of the water declines, and anoxia may lead to fish kills . Of particular concern is the possibility of cyanobacteria blooms that create compounds toxic for humans. Many of the waters across Nebraska receive excessive nutrients from human activities, largely related to agriculture (Dickey 1982). However, there is one river, the Niobrara River, …
Transect Survey Biases And Correction Methods In Southern Africa, Erika Swenson, Larkin Powell
Transect Survey Biases And Correction Methods In Southern Africa, Erika Swenson, Larkin Powell
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In southern Africa, transect surveys and distance-based analyses are often used to obtain density and population estimates for species in large reserves or management zones. However, these estimates may be biased by unnaturally large concentrations of animals at waterholes that are on or near the path of the transect. We used empirical survey data from the Namibrand Nature Reserve in southwest Namibia to parameterize spatial simulations in which we distributed gemsbok (Oryx gazella) on a grid along a 50-kilometer transect. We created multiple simulations with and without waterholes to determine how the proportion of animals clumped at the …
Modeling Predator-Prey Interaction In A Two Patch System, Marc Wade
Modeling Predator-Prey Interaction In A Two Patch System, Marc Wade
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In this study we examine predator-prey relationships in the context of a two patch system. What is meant by a two patch system is that prey live in a habitat that consists of type 1 patches with an abundance of food and type 2 patches with no food. In our study, we will be assuming that predators cannot enter the first type of patch. We combine three well-established ecological theories: migration theory, optimal foraging theory, and the standard predator-prey model in order to answer the motivating question: "Under what environmental conditions is a predator population stable when predation can only …
Using Electrocoagulation To Remove Perfluoroalkyl And Polyfluoroalkyl Substances (Pfas) From Contaminated Water, Amy Yanagida
Using Electrocoagulation To Remove Perfluoroalkyl And Polyfluoroalkyl Substances (Pfas) From Contaminated Water, Amy Yanagida
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Perfluoroalkyl and Polyfluoroalkyl substances (PFAS) are a family of manmade chemicals that are used to improve the quality of several commercial products by making them resistant to heat, oil, stains, grease and water. Unfortunately, the chemical properties that make PFAS useful from an industrial perspective also make them mobile and recalcitrant once released into the environment. We used electrocoagulation to run a direct current through contaminated water to generate a zinc floc to precipiate PFAS out of water.
Explainable Deep Learning For Medical Image Analysis, Brennan Rhoadarmer
Explainable Deep Learning For Medical Image Analysis, Brennan Rhoadarmer
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Explainable Deep Learning for Medical Image Analysis is a project focused on improving the ability for deep learning models to explain the reasoning behind their classification in order to improve their viability in the medical field, where explanations of decisions is critical for the care of patients. In order to explore this topic, we work to implement GradCAM, which is a new method of determining the cause classification in models by tracing back through the model layers to the input.
Crystallization At Droplet Interfaces For The Fabrication Of Geometrically Programmed Synthetic Magnetosomes, Matthew Gromowsky, Michael Stoller, Maddee Rauhauser, Marcus Judah, Abhiteja Konda, Christopher Jurich, Stephen Morin
Crystallization At Droplet Interfaces For The Fabrication Of Geometrically Programmed Synthetic Magnetosomes, Matthew Gromowsky, Michael Stoller, Maddee Rauhauser, Marcus Judah, Abhiteja Konda, Christopher Jurich, Stephen Morin
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Many organisms rely on the precise growth, assembly, and/or organization of inorganic crystals to achieve vital functions, for example, three-dimensional structural support (i.e., skeletal systems based on calcite) or environmental sensing (i.e., magnetosomes based on magnetite). Mimicking the production of the complex products observed in these biomineralization processes, synthetically, remains challenging. Herein, a method for the synthesis of artificial magnetosomes with programmable magnetic domains was developed. Specifically, precursors were compartmentalized inside different surfactant-stabilized aqueous-phase droplets suspended in oil and microfluidic technologies were implemented to control their interactions precisely. When reactive droplets were brought into contact with one another, a lipid …