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Articles 30421 - 30450 of 302505

Full-Text Articles in Physical Sciences and Mathematics

Finite-Difference-Time-Domain Simulation Of Ultrafast Experiments, Alpha Ma May 2022

Finite-Difference-Time-Domain Simulation Of Ultrafast Experiments, Alpha Ma

Macalester Journal of Physics and Astronomy

The Finite-Difference-Time-Domain (FDTD) method is a numerical method that calculates electric fields or magnetic fields by interleaving them in space and time. Using a python package called “MEEP”, I was able to write optical simulations of ultrafast experiments, especially the Terahertz Pump-Probe experiments. The goal of this project was to use FDTD simulation to measure the transmission of an electro-magnetic pulse passing through a thin film of conducting material on a dielectric substrate in order to study the characteristic conductivity of potential solar cell materials.

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Molecular Line Search In Archival Alma Imaging Of M87, Xueyi Li May 2022

Molecular Line Search In Archival Alma Imaging Of M87, Xueyi Li

Macalester Journal of Physics and Astronomy

We present a molecular line search in spectral imaging of the elliptical galaxy M87 using archival data from the Atacama Large Millimeter/sub-millimeter Array (ALMA). The primary goal of this project is to verify and characterize possible CO transition lines, which can be used for future studies to determine the dynamics of the system, or the mass of the supermassive black hole (BH) in the center of the galaxy. After performing extensive atmospheric modeling, we found that most of the absorption features have a corresponding atmospheric ozone transition, so it is unlikely that these features are either Galactic or extragalactic. We …

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Lie Algebras And The Poincare Group, Jack Hempel Costello May 2022

Lie Algebras And The Poincare Group, Jack Hempel Costello

Macalester Journal of Physics and Astronomy

This paper will discuss my research with
Professor Tonnis ter Veldhuis on the Poincare Group
and other similar algebraic approaches based on the
Minkowski Metric. This paper will begin with an
introduction discussing group theory and expand on its
specific applications in theoretical physics.

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Simulating Interactions Between Coronal Mass Ejections, Damen S. Beverlin, Tatiana Niembro May 2022

Simulating Interactions Between Coronal Mass Ejections, Damen S. Beverlin, Tatiana Niembro

Macalester Journal of Physics and Astronomy

Coronal mass ejections (CMEs) launch large amounts of plasma and magnetic fields into the interplanetary medium. Under the right initial conditions, this ejecta can reach Earth and cause issues with electronic devices. As such, we would like to have an accurate model that depicts how these CMEs propagate as they leave the sun. By using fluid dynamics and one-minute resolution in-situ solar wind data, we sought to simulate CME plasma propagation with analytical and numerical models. Because the interstellar medium contains other material and other events happen on the sun simultaneously, CMEs can interact with each other and other ejecta, …

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Custom Calibration And Correction Of Photoemission Electron Microscope Images Using Graphene, Henry Bell May 2022

Custom Calibration And Correction Of Photoemission Electron Microscope Images Using Graphene, Henry Bell

Macalester Journal of Physics and Astronomy

The Photoemission Electron Microscope (PEEM) is a full-field electron microscope that utilizes the photoelectric effect to image a surface. Due to a spatial resolution on the order of 10 nanometers and its ability to image both the morphology of a surface and its band structure, it is a useful tool for understanding the properties of materials for use in electronic devices. To correct for random sample misalignment and the experimental frame of reference in the spectroscopy mode of the PEEM, the 3D dataset must be rotated in both the momentum and energy coordinates which requires pixel calibration and energy alignment. …

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Knocking Down Nox: Examining The Effects Of Transportation Electrification On Urban Ozone Production In The South Coast Air Basin, Jason Beal May 2022

Knocking Down Nox: Examining The Effects Of Transportation Electrification On Urban Ozone Production In The South Coast Air Basin, Jason Beal

Macalester Journal of Physics and Astronomy

With last year’s commitment to all in-state sales of new passenger cars and trucks being zero-emission by 2035 (California Executive Order N-79-20), California is leading the charge for transportation electrification in the United States. Despite being at the forefront of climate change management and mitigation, California has some of the worst air quality in the nation. While primarily motivated by a desire to reduce carbon dioxide emissions and reliance on fossil fuels, transportation electrification will also have a significant impact on local air quality. The goal of this study is to quantify and qualify this impact in the context of …

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Tiling Rectangles And 2-Deficient Rectangles With L-Pentominoes, Monica Kane May 2022

Tiling Rectangles And 2-Deficient Rectangles With L-Pentominoes, Monica Kane

Rose-Hulman Undergraduate Mathematics Journal

We investigate tiling rectangles and 2-deficient rectangles with L-pentominoes. First, we determine exactly when a rectangle can be tiled with L-pentominoes. We then determine locations for pairs of unit squares that can always be removed from an m × n rectangle to produce a tileable 2-deficient rectangle when m ≡ 1 (mod 5), n ≡ 2 (mod 5) and when m ≡ 3 (mod 5), n ≡ 4 (mod 5).

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Prospects For Legal Analytics: Some Approaches To Extracting More Meaning From Legal Texts, Kevin D. Ashley May 2022

Prospects For Legal Analytics: Some Approaches To Extracting More Meaning From Legal Texts, Kevin D. Ashley

University of Cincinnati Law Review

No abstract provided.

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Wind Effects On Near- And Midfield Mixing In Tidally Pulsed River Plumes, Preston Spicer, Kelly L. Cole, Kimberly Huguenard, Daniel G. Macdonald, Michael M. Whitney May 2022

Wind Effects On Near- And Midfield Mixing In Tidally Pulsed River Plumes, Preston Spicer, Kelly L. Cole, Kimberly Huguenard, Daniel G. Macdonald, Michael M. Whitney

Civil Engineering Faculty Scholarship

River plumes transport and mix land-based tracers into the ocean. In tidally pulsed river plumes, wind effects have long been considered negligible in modulating interfacial mixing in the energetic nearfield region. This research tests the influence of variable, realistic winds on mixing in the interior plume. A numerical model of the Merrimack River plume-shelf system is utilized, with an application of the salinity variance approach employed to identify spatial and temporal variation in advection, straining, and dissipation (mixing) of vertical salinity variance (stratification). Results indicate that moderate wind stresses (∼0.5 Pa) with a northward component countering the downcoast rotation of …

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Geodesic Bicombings On Some Hyperspaces, Logan S. Fox May 2022

Geodesic Bicombings On Some Hyperspaces, Logan S. Fox

Mathematics and Statistics Faculty Publications and Presentations

We show that if (X,d)" role="presentation" style="box-sizing: inherit; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">(X,d)(X,d) is a metric space which admits a consistent convex geodesic bicombing, then we can construct a conical bicombing on CB(X)" role="presentation" style="box-sizing: inherit; display: inline; line-height: normal; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; padding: 0px; margin: 0px; position: relative;">CB(X)CB(X), the hyperspace of nonempty, closed, bounded, and …

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A New Model For Predicting The Drag And Lift Forces Of Turbulent Newtonian Flow On Arbitrarily Shaped Shells On The Seafloor, Carley R. Walker, James V. Lambers, Julian Simeonov May 2022

A New Model For Predicting The Drag And Lift Forces Of Turbulent Newtonian Flow On Arbitrarily Shaped Shells On The Seafloor, Carley R. Walker, James V. Lambers, Julian Simeonov

Dissertations

Currently, all forecasts of currents, waves, and seafloor evolution are limited by a lack of fundamental knowledge and the parameterization of small-scale processes at the seafloor-ocean interface. Commonly used Euler-Lagrange models for sediment transport require parameterizations of the drag and lift forces acting on the particles. However, current parameterizations for these forces only work for spherical particles. In this dissertation we propose a new method for predicting the drag and lift forces on arbitrarily shaped objects at arbitrary orientations with respect to the direction of flow that will ultimately provide models for predicting the sediment sorting processes that lead to …

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Analysis Of Fossil Pollen From A Pleistocene Cypress Forest Preserved On The Northern Gulf Of Mexico Continental Shelf, Kathryn Joyce Garretson May 2022

Analysis Of Fossil Pollen From A Pleistocene Cypress Forest Preserved On The Northern Gulf Of Mexico Continental Shelf, Kathryn Joyce Garretson

Master's Theses

This study presents the findings of fossil pollen analysis performed on terrestrial sediments preserved on the northern Gulf of Mexico continental shelf (site hereafter known as the Underwater Forest or DF). This research aims to establish vegetation composition on a continental shelf glacial refuge and provide a better understanding of vegetation response to sea-level rise. Two cores (15DF1 and 15DF3B) located at different locations within the forest were recovered and analyzed. Pollen results from both cores were similar, with high percentages of Taxodium and Nyssa pollen in the lowermost sections reflecting an assemblage typical of contemporary baldcypress swamps. Pollen assemblages …

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Analyzing The Interactions Of Thermoresponsive Coacervate-Forming Biodegradable Polyester Encapsulation On Model Protein Structure And Activity, Conner Casterline May 2022

Analyzing The Interactions Of Thermoresponsive Coacervate-Forming Biodegradable Polyester Encapsulation On Model Protein Structure And Activity, Conner Casterline

Master of Science in Chemical Sciences Theses

Protein therapeutics hold high efficacy in treatment for various diseases including cancer and diabetes. However, the treatment cost is generally higher than other therapeutics mainly due to in vivo protein degradation. This drawback creates demand for more efficient delivery methods to preserve the function and integrity of protein therapeutics. Thermoresponsive coacervate-forming biodegradable polyesters (TR-PEs) are a thermoresponsive molecular packaging system used in protein therapeutic research. The term coacervate refers to a phase-separated solution in which a dense polymer phase separates from the aqueous phase to form nanodroplets within solution, capturing bioactive molecules. Limited research demonstrates if TR-PEs can encapsulate and …

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Large Scale Disease Modeling, Walker Mattox May 2022

Large Scale Disease Modeling, Walker Mattox

Master's Theses

In this we study large scale disease modeling. After understanding the mechanics behind the SIR disease model in an ODE sense, we will apply this knowledge to model disease spread in more and more increasing advanced cellular automata. Eventually, some of our cellular automata will include long distance travel. From this discrete data, we can then build an SIR model in the PDE sense to display large scale disease spread.

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Final Residential Metals Abatement Program (Rmap) Quality Assurance Project Plan (Qapp) (Non-Residential Parcels), Pioneer Technical Services, Inc. May 2022

Final Residential Metals Abatement Program (Rmap) Quality Assurance Project Plan (Qapp) (Non-Residential Parcels), Pioneer Technical Services, Inc.

Silver Bow Creek/Butte Area Superfund Site

No abstract provided.

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Inorganic Cesium Lead Mixed Halide Based Perovskite Solar Materials Modified With Functional Silver Iodide, Vincent Obiozo Eze, Lucas Braga Carani, Haimanti Majumder, M. Jasim Uddin, Okenwa Okoli May 2022

Inorganic Cesium Lead Mixed Halide Based Perovskite Solar Materials Modified With Functional Silver Iodide, Vincent Obiozo Eze, Lucas Braga Carani, Haimanti Majumder, M. Jasim Uddin, Okenwa Okoli

Chemistry Faculty Publications and Presentations

Inorganic CsPbIBr2 perovskites have recently attracted enormous attention as a viable alternative material for optoelectronic applications due to their higher efficiency, thermal stability, suitable bandgap, and proper optical absorption. However, the CsPbIBr2 perovskite films fabricated using a one-step deposition technique is usually comprised of small grain size with a large number of grain boundaries and compositional defects. In this work, silver iodide (AgI) will be incorporated as an additive into the CsPbIBr2 perovskite precursor solution to prepare the unique perovskite CsI(PbBr2)1-x(AgI)x. The AgI additive in the precursor solution works as a nucleation promoter which will help the perovskite to grow …

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Identifying Key Stream Restoration Variables In An Agriculturally Impaired Chesapeake Bay Watershed, Julia Portmann May 2022

Identifying Key Stream Restoration Variables In An Agriculturally Impaired Chesapeake Bay Watershed, Julia Portmann

Masters Theses, 2020-current

The Chesapeake Bay watershed spans several states, supports diverse ecosystems, and is crucial to local economies. However, agricultural practices in this region impair water quality. The Smith Creek watershed, within the Shenandoah Valley, was designated a showcase watershed in 2010 by the United States Department of Agriculture to demonstrate the efficacy of implementing restoration projects. We sampled fifteen farms ranging from unrestored to thirty-six years since restoration. At each site, we conducted a kick-net survey for macroinvertebrates, measured canopy cover, algal density, substrate size, and bank height and angle. We identified macroinvertebrates to family and calculated the Chesapeake Basin-wide Index …

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The Identification And Quantification Of Organophosphate Flame Retardants In Raw Materials Utilized In Polyurethane Production, Lindsay Tudor May 2022

The Identification And Quantification Of Organophosphate Flame Retardants In Raw Materials Utilized In Polyurethane Production, Lindsay Tudor

Master of Science in Chemical Sciences Theses

Flame retardant additives are utilized in various polyurethane applications to comply with industry and flammability standards. Federal regulations and restrictive standards continue to tighten controls on certain impurities found in flame retardant blends. These restrictions include the limitation of organophosphates. Extensive research has been conducted to examine the effects of organophosphates in humans. To date, researchers have predominantly focused on the final product, mainly furniture and bedding products, rather than the raw materials utilized in production. Industrial chemists continue to grapple with the development of an effective method for detecting and quantifying organophosphate compounds in various flame retardant mixtures as …

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Shining A Light On Marginal Food Insecurity In An Understudied Population Comment, Angela D. Liese May 2022

Shining A Light On Marginal Food Insecurity In An Understudied Population Comment, Angela D. Liese

Faculty Publications

No abstract provided.

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Tabletop Extreme-Ultraviolet Source Using High Harmonic Generation For Polarization Sensitive Imaging, Taylor Jordan Buckway May 2022

Tabletop Extreme-Ultraviolet Source Using High Harmonic Generation For Polarization Sensitive Imaging, Taylor Jordan Buckway

Theses and Dissertations

We are developing a tabletop extreme-ultraviolet source using high harmonic generation at Brigham Young University. The thesis goes over the theory of high harmonic generation using the three-step model. This tabletop source was designed for probing magnetic domains of iron nanoparticles. We present optimization of the 42 eV and 52 eV harmonics through phase matching. Phase matching consists of tuning the intensity of the IR beam and pressure of the gas medium. The target gas medium used for this thesis is argon. The 42 eV harmonic was optimized to 8.2 billion photons per second. This was used with a 1500 …

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Prediction And Confirmation Of A Switch-Like Region Within The N-Terminal Domain Of Hsirt1, Angelina T. Huynh, Thi-Tina N. Nguyen, Carina A. Villegas, Saira Montemorso, Benjamin Strauss, Richard A. Pearson, Jason G. Graham, Jonathan Oribello, Rohit Suresh, Brooke Lustig, Ningkun Wang May 2022

Prediction And Confirmation Of A Switch-Like Region Within The N-Terminal Domain Of Hsirt1, Angelina T. Huynh, Thi-Tina N. Nguyen, Carina A. Villegas, Saira Montemorso, Benjamin Strauss, Richard A. Pearson, Jason G. Graham, Jonathan Oribello, Rohit Suresh, Brooke Lustig, Ningkun Wang

Faculty Research, Scholarly, and Creative Activity

Many proteins display conformational changes resulting from allosteric regulation. Often only a few residues are crucial in conveying these structural and functional allosteric changes. These regions that undergo a significant change in structure upon receiving an input signal, such as molecular recognition, are defined as switch- like regions. Identifying these key residues within switch-like regions can help elucidate the mechanism of allosteric regulation and provide guidance for synthetic regulation. In this study, we combine a novel computational workflow with biochemical methods to identify a switch-like region in the N-terminal domain of human SIRT1 (hSIRT1), a lysine deacetylase that plays important …

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Characterization Of Bimetallic Silver-Copper Nanoinks With Hydroxyethyl-Cellulose Additives, Daniel Brunick May 2022

Characterization Of Bimetallic Silver-Copper Nanoinks With Hydroxyethyl-Cellulose Additives, Daniel Brunick

Undergraduate Honors Theses

Coinage metal nanoparticles remain an intriguing subject for research due to their industrial versatility. Primary applications of coinage metal nanoparticles include printed electronics, solar panels, and sensors. Inks formulated with the nanoparticles are conductive and thus useful for fabricating sensors. Silver-copper nanoalloy inks are viable for the fabrication of flexible sensing devices for the detection of volatile organic compounds. One of the challenges is the ability to synthesize composition-controllable alloy nanoparticles at room temperature through wet chemical methods and achieve controllable sintering at room temperature. This work addresses the challenges by investigating the room-temperature synthesis of silver-copper alloy nanoparticles and …

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Synthesis And Characterization Of Hydrazine Derivatives Of Coumarin For Bioorthogonal Chemistry Inside Cells, Akiva J. Grimaldi May 2022

Synthesis And Characterization Of Hydrazine Derivatives Of Coumarin For Bioorthogonal Chemistry Inside Cells, Akiva J. Grimaldi

Undergraduate Honors Theses

Protein carbonylation is one manifestation of oxidative stress, which is characteristic of many diseases. Our lab has developed several coumarin-hydrazine based fluorescent probes capable of detecting carbonylation in live cells via the formation of hydrazone conjugates. As an effort to expand and improve on these achievements, this work presents new data regarding the synthesis and characterization of three such probes. Two of the probes—julolidine coumarin hydrazide (JCH) and trifluoromethyl coumarin hydrazine (TFCH)—were previously synthesized by our lab. Here, JCH is studied in terms of its reaction speed and fluorescence enhancement in acylhydrazone formation with aldehydes under various conditions and catalytic …

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A Survey On Cache-Aided Noma For 6g Networks, Dipen Bepari, Soumen Mondal, Aniruddha Chandra, Rajeev Shukla, Yuanwei Liu, Mohsen Guizani, Arumugam Nallanathan May 2022

A Survey On Cache-Aided Noma For 6g Networks, Dipen Bepari, Soumen Mondal, Aniruddha Chandra, Rajeev Shukla, Yuanwei Liu, Mohsen Guizani, Arumugam Nallanathan

Machine Learning Faculty Publications

Contrary to orthogonal multiple-access (OMA), non-orthogonal multiple-access (NOMA) schemes can serve a pool of users without exploiting the scarce frequency or time domain resources. This is useful in meeting the sixth generation (6G) network requirements, such as, low latency, massive connectivity, users' fairness, and high spectral efficiency. On the other hand, content caching restricts duplicate data transmission by storing popular contents in advance at the network edge which reduces 6G data traffic. In this survey, we focus on cache-aided NOMA-based wireless networks which can reap the benefits of both cache and NOMA; switching to NOMA from OMA enables cache-aided networks …

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Using Lidar To Estimate Carbon Sequestration Of Evergreen Trees At Eastern Washington University (Ewu) Campus, Cheney, Washington, Kristy A. Snyder May 2022

Using Lidar To Estimate Carbon Sequestration Of Evergreen Trees At Eastern Washington University (Ewu) Campus, Cheney, Washington, Kristy A. Snyder

2022 Symposium

EWU contains a variety of deciduous and evergreen trees across its campus, providing several benefits. However, no comprehensive record exists of the total number, location, species, or ages of these trees. This knowledge can inform facilities of proper care for individual trees and can be used to estimate carbon sequestration on campus. Traditional on-the-ground methods for assessing trees require tree cores or clinometers, making trees susceptible to pests or disease and leading to inaccurate results. Remote sensing using lidar data is a noninvasive, more precise method to measure tree height and subsequently assess tree age. This poster explores using point …

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Using Geologic Principles And Data To Create A Symphony For Wind Ensemble, Thomas J. Davis May 2022

Using Geologic Principles And Data To Create A Symphony For Wind Ensemble, Thomas J. Davis

2022 Symposium

Geology and geologic processes have featured in many pieces of classical music such as Alan Hovhaness’ symphonic works after Mt. St. Helens and Glacier Peak but these pieces are impressionistic and only take general inspiration from the geology of their subjects. This paper describes the creation of Tectonics (2021) a piece which incorporates and describes many geologic principles and processes, such as mantle convection, through the musical form of cannon, the formation of fold and thrust belts whose cross sections are directly visually recreated in the score, and the physical dynamics of earthquake waves demonstrated through variations of pitch and …

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Mapping The Covid-19 Pandemic In Staten Island, Vincenzo Mezzio May 2022

Mapping The Covid-19 Pandemic In Staten Island, Vincenzo Mezzio

Student Theses

COVID-19 has had diverging effects in New York City. Out of the five boroughs, Staten Island has one of the largest percentages of COVID-19 cases relative to population. This research examines key social and spatial factors that contribute to the increase in COVID-19 cases in Staten Island). It asks: Which parts of Staten Island have higher rates of transmission of COVID-19? Which parts of the borough have higher population who are more vulnerable to COVID-19? What is the relationship between the location of vaccination centers with the rates of COVID-19 cases? Using Geographic Information Systems (GIS), this research examines the …

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Genetic Structure Of Urban White-Tailed Deer In West Michigan, Jacob David Brand May 2022

Genetic Structure Of Urban White-Tailed Deer In West Michigan, Jacob David Brand

Masters Theses

In urban areas, green spaces are used by humans and wildlife. The proximity between them can lead to both positive and negative interactions, which can make managing urban wildlife difficult. Managers are challenged due to conflicts between wildlife population sizes that can be naturally supported versus those that are socially tolerable. White-tailed deer (Odocoileus virginianus) thrive in urban environments because their habitat requirements are met within green spaces and backyard vegetation. Matrilineal groups of urban white-tailed deer live within the same areas, at times forming high densities that can lead to the spread of diseases or environmental pests, including hemlock …

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Novel Instance-Level Weighted Loss Function For Imbalanced Learning, Trent Geisler May 2022

Novel Instance-Level Weighted Loss Function For Imbalanced Learning, Trent Geisler

Doctor of Data Science and Analytics Dissertations

Binary classification using imbalanced datasets remains a challenge. Typically, supervised learning algorithms minimize the binary cross-entropy objective function to determine the final parameter estimates. This objective function assumes an equal class distribution between the minority (i.e. events) and majority (i.e. non-events) classes, which almost never exists in real-world modeling. In the imbalanced data setting, the equal class distribution is grossly violated, and the resulting parameter estimates are biased toward the majority class. To overcome the bias and improve model generalization, we focus on modifying the original binary cross-entropy objective function by uniquely weighting each minority class observation. We base our …

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Synthesis And Characterization Of Sustainable And Biobased Copolymers From Lignocellulosic, Guery Saenz May 2022

Synthesis And Characterization Of Sustainable And Biobased Copolymers From Lignocellulosic, Guery Saenz

Theses and Dissertations

Natural compounds have been the primary resource used to produce polymeric materials by humankind since the mid-1900s. Yet, progress in bio-based polymers from renewable feedstock has encountered some obstacles, mainly due to the low prices of petroleum-based monomers, compared to natural and sustainable materials. However, most commodity plastics are non-degradable materials, and solid plastic waste accumulation adversely affects the environment. As the world population is growing and demanding chemicals, energy, and plastics materials, polymer research is focusing on synthesizing bio-based and degradable polymers. Thus, biomass, a sustainable and inexpensive feedstock, is highly appropriate for designing alternative thermoplastics that are degradable …

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