Physical Sciences and Mathematics Commons^™

Ultrafast Spin-Currents And Charge Conversion At 3d-5d Interfaces Probed By Time-Domain Terahertz Spectroscopy, T. H. Dang, J. Hawecker, E. Rongione, G. Baez Flores, D. Q. To, J. C. Rojas-Sanchez, H. Nong, J. Mangeney, J. Tignon, F. Godel, S. Collin, P. Seneor, M. Bibes, A. Fert, M. Anane, J. M. George, L. Vila, M. Cosset-Cheneau, D. Dolfi, R. Lebrun, P. Bortolotti, Kirill Belashchenko, S. Dhillon, H. Jaffrès

Kirill Belashchenko Publications

Spintronic structures are extensively investigated for their spin-orbit torque properties, required for magnetic commutation functionalities. Current progress in these materials is dependent on the interface engineering for the optimization of spin transmission. Here, we advance the analysis of ultrafast spin-charge conversion phenomena at ferromagnetic-Transition metal interfaces due to their inverse spin-Hall effect properties. In particular, the intrinsic inverse spin-Hall effect of Pt-based systems and extrinsic inverse spin-Hall effect of Au:W and Au:Ta in NiFe/Au:(W,Ta) bilayers are investigated. The spin-charge conversion is probed by complementary techniques-ultrafast THz time-domain spectroscopy in the dynamic regime for THz pulse emission and ferromagnetic resonance spin-pumping …

Remediating Contaminated Groundwater With An Aerated, Direct-Push, Oxidant Delivery System, James Reece, Mark Christenson, Ann Kambhu, Yusong Li, Clifford Harris, Steve D. Comfort

School of Natural Resources: Faculty Publications

One of the biggest challenges to treating contaminated aquifers with chemical oxidants is achieving uniform coverage of the target zone. In an effort to maximize coverage, we report the design and installation of a novel aerated, slow-release oxidant delivery system that can be installed by direct-push equipment. By continuously bubbling air beneath a slow-release oxidant in situ, an airlift pump is created that causes water and oxidant to be dispersed from the top of the outer screen and drawn in at the bottom. This continuous circulation pattern around each drive point greatly facilitates the spreading of the oxidant as it …

Harmful Algal Blooms Threaten The Health Of Peri-Urban Fisher Communities: A Case Study In Kisumu Bay, Lake Victoria, Kenya, Amber Roegner, Lewis Sitoki, Chelsea Weirich, Jessica Corman, Dickson Owage, Moses Umami, Ephraim Odada, Jared Miruka, Zachary Ogari, Woutrina Smith, Eliska Rejmankova, Todd R. Miller

School of Natural Resources: Faculty Publications

Available guidance to mitigate health risks from exposure to freshwater harmful algal blooms (HABs) is largely derived from temperate ecosystems. Yet in tropical ecosystems, HABs can occur year-round, and resource-dependent populations face multiple routes of exposure to toxic components. Along Winam Gulf, Lake Victoria, Kenya, fisher communities rely on lake water contaminated with microcystins (MCs) from HABs. In these peri-urban communities near Kisumu, we tested hypotheses that MCs exceed exposure guidelines across seasons, and persistent HABs present a chronic risk to fisher communities through ingestion with minimal water treatment and frequent, direct contact. We tested source waters at eleven communities …

On Higher-Order Duality In Nondifferentiable Minimax Fractional Programming, S. Al-Homidan, Vivek Singh, I. Ahmad

Applications and Applied Mathematics: An International Journal (AAM)

In this paper, we consider a nondifferentiable minimax fractional programming problem with continuously differentiable functions and formulated two types of higher-order dual models for such optimization problem.Weak, strong and strict converse duality theorems are derived under higherorder generalized invexity.

Analyzing Strain Localization, Kinematic Partitioning And Fluid Flow In The Pulo Do Lobo Metasedimentary Rocks Along The Southern Iberian Shear Zone, Andalucia, Spain, Nancy Alejandra Carman

Theses and Dissertations

The Southern Iberian Shear Zone is a regional scale ductile shear zone that placed Beja-Acebuches metabasites over metapelite and quartzite rocks of the Pulo do Lobo Formation in a transpressional deformation with components of thrust and left-lateral movement. This project evaluates factors that contributed to strain localization at a variety of scales within the Pulo do Lobo formation, including lithologic variations, microstructures, and fluid flow. Additionally, microstructural data are used to test whether kinematic partitioning accompanied strain localization. Grain scale asymmetric indicators of sigma-type clasts, S-C fabrics, and asymmetric folds indicate dominant thrust motion. Strain intensity and metamorphic grade increase …

Surface Alteration In The Ölkelduháls, Nesjavellir, And Geysir Hydrothermal Systems, Iceland: Implications For Mars, Jordan Ludyan

Theses and Dissertations

Silica- and sulfate-rich deposits observed by Mars Exploration Rover (MER) Spirit near Home Plate, Gusev crater, Mars, indicate alteration of Mars basalt by a diverse array of hydrothermal fluids and processes. Constraining the precise fluid conditions present at the time of deposition for these deposits on Mars relies on investigations of terrestrial hydrothermal systems that produce similar mineral assemblages. Alteration products and fluids collected from the Ölkelduháls, Nesjavellir, and Geysir hydrothermal areas in southern Iceland cover a wide range of end-member and intermediate fluid and alteration environments, and provide a means to compare the secondary minerals produced from different hydrothermal …

Sustainability In Construction: Using Lean Management Principles To Reduce Waste, Matthew Waite

Theses and Dissertations

The construction industry is facing many challenges. There are growing consumer demands for sustainable building. The construction industry generates a significant portion of the waste going into landfills. The construction industry has failed to keep pace with productivity in the manufacturing industry. Through adoption of Lean management principles, the construction industry can become more sustainable while increasing productivity. The literature was evaluated for three concepts: Lean management principles interaction with sustainability, the current state of sustainability in the construction industry, and the current state of Lean management principles in the construction industry. Lean management philosophies interactions with sustainability has been …

On Subdiagonal Rational Pade Approximations And The Brenner-Thomee Approximation Theorem For Operator Semigroups, Frank Neubrander, Koray Ozer, Lee Windsperger

Faculty Publications

The computational powers of Mathematica are used to prove polynomial identities that are essential to obtain growth estimates for subdiagonal rational Pade approximations of the exponential function and to obtain new estimates of the constants of the Brenner-Thomee Approximation Theorem of Semigroup Theory.

Economics And Game Theory, Jeremiah Patrick Prenn

Mathematics Senior Showcase 2020

Game theory is one of the major fields of mathematics. Game theory is the study of how games, their players, and players’ strategies are defined, and how the games might play out. The outcomes of games are ultimately based on decisions, much like in the science of economics. Economics analyzes how scarce resources are to be allocated to suit unlimited needs. Every decision has an economic cost, and every decision has a utility value (utility being a quantitative measure of usefulness). Economics and game theory go hand in hand: Both analyze the effects of decisions and the rules imposed on …

The History And Application Of Benford's Law, Hunter Clark

Mathematics Senior Showcase 2020

My Poster is on the history and application of Benford’s law. This is a law that states that the leading digit of a set of numbers will be the number 1 approximately 30% of the time. This is a natural phenomenon and what I mean by that is that in order for this law to hold the numbers cannot be assigned. They must be random as in financial statements or logs. This law does not work on sets that are assigned such as time sheets and addresses. You will see in my poster that the original person to discover this …

Using The Chi-Square Test To Analyze Voter Behavior, Bailey Fadden

Mathematics Senior Showcase 2020

We explain the Chi-Square Test and how to use it to analyze voter behavior. Specifically we look at the behavior of U.S citizens and whether or not they voted in the 2016 U.S presidential election, and how this relates to income.

Morse-Code Encoded Eye Blinking As A Source Of Biometric Authentication Via Eeg, Ben Adams, Meghan Edgerton, Gabe Miles, Callum Young

Mathematics Senior Showcase 2020

Brain-Computer Interfaces (BCIs) have historically provided many uses in the medical field, including mobility for individuals with differing levels of paralysis. Present day research is focused around testing the efficacy of such devices on mental diseases such as Alzheimer's, Dementia, and Parkinson's. Leading companies that are spearheading the research of such devices, are looking at BCI's as a tool for solving many of the problems that these diseases produce, with the end goal of generalizing BCIs to appeal to the healthy layperson by providing an additional interface between them and the technological world. If such devices were present in society …

Internal Sorting Methods, Rebekah Marie Bitikofer

Mathematics Senior Showcase 2020

Internal sorting methods are possible when all of the items to be accessed fit in a computer's high-speed internal memory. There are quite a few (Knuth's third volume of The Art of Computer Programming covers 14 in total) but I will go over the four I found to be most versatile and useful. Each algorithm that I cover has a specific benefit that merits its' use in computer science. Some have faster run times (Heapsort), simpler code (Straight Insertion), run with a smaller memory space (Quicksort), or work well with large sets (Radix Sorting). Different sorting tasks lead users to …

Cybersecurity Of The Artificial Pancreas, D. J. Cooke, Andres Guzman, Robert Kinney, Christine Patterson, Josh Stone

Mathematics Senior Showcase 2020

We live in a world of cyber-enabled devices that enhance many aspects of life, including the treatment of diabetes. Type I Diabetes is a chronic autoimmune disorder characterized by destruction of pancreatic cells and subsequent deficiency of insulin - a crucial hormone in regulating blood glucose levels. The development of an Artificial Pancreas System is automating the maintenance of this disease by integrating wireless devices to continuously balance blood glucose levels without patient interaction. An integral part of this system is the Continuous Glucose Monitor (CGM) which wirelessly transmits blood glucose measurements every 5 minutes. CGMs and other Implantable Medical …

Construction Of A First Order Logic Theorem Prover, Luke Philip Tyler

Mathematics Senior Showcase 2020

There are many systems that have been researched in the past on automating the process of theorem proving in first-order logic. This research explores one of these systems, the tableau method. A point of interest within the tableau method is whether or not the method is sound and complete. This research was done in tandem with a computer implementation of the tableau method written in Haskell. The basic design of the implementation was to construct a fair rule for tableau expansion and expand the tableau until it was found to be closed, open, or infinite, thereby proving or disproving of …

Need For Shift-Invariant Fractional Differentiation Explains The Appearance Of Complex Numbers In Physics, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

Complex numbers are ubiquitous in physics, they lead to a natural description of different physical processes and to efficient algorithms for solving the corresponding problems. But why this seemingly counterintuitive mathematical construction is so natural here? In this paper, we provide a possible explanation of this phenomenon: namely, we show that complex numbers appear if take into account that some physical system are described by derivatives of fractional order and that a physically meaningful analysis of such derivatives naturally leads to complex numbers.

Why Physical Processes Are Smooth Or Almost Smooth: A Possible Physical Explanation Based On Intuitive Ideas Behind Energy Conservation, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

While there are some non-smooth (and even discontinuous) processes in nature, most processes are smooth or almost smooth. This smoothness help estimate physical quantities, but a natural question is: why are physical processes smooth or almost smooth? Are there any fundamental reasons for this ubiquitous smoothness? In this paper, we provide a possible physical explanation for emirical smoothness: namely, we show that smoothness naturally follows from intuitive ideas behind energy conservation.

Building Postsecondary Pathways For Latinx Students In Computing: Lessons From Hispanic-Serving Institutions, Anne-Marie Núñez, David S. Knight, Sanga Kim

Departmental Technical Reports (CS)

While the COVID-19 pandemic has transformed the use of technology in education and the workforce, a shortage of computer scientists continues, and computing remains one of the least diverse STEM disciplines. Efforts to diversify the computing industry often focus on the most selective postsecondary institutions, which are predominantly White. We highlight the role of Hispanic-Serving Institutions (HSI) in gradating large numbers of STEM graduates of color, particularly Latinx students. HSIs are uniquely positioned to leverage asset-based approaches that value students’ cultural background. We describe the practices educators use in the Computing Alliance for Hispanic-Serving Institutions, a network of 40 HSIs …

So How Were The Tents Of Israel Placed? A Bible-Inspired Geometric Problem, Julio Urenda, Olga Kosheleva, Vladik Kreinovich

Departmental Technical Reports (CS)

In one of the Biblical stories, prophet Balaam blesses the tents of Israel for being good. But what can be so good about the tents? A traditional Rabbinical interpretation is that the placement of the tents provided full privacy: from each entrance, one could not see what is happening at any other entrance. This motivates a natural geometric question: how exactly were these tents placed? In this paper, we provide an answer to this question.

Socio-Hydrology: An Interplay Of Design And Self-Organization In A Multilevel World, Vicken Hillis

Human-Environment Systems Research Center Faculty Publications and Presentations

The emerging field of socio-hydrology is a special case of social-ecological systems research that focuses on coupled human-water systems, exploring how the hydrologic cycle and human cultural traits coevolve and how such coevolutions lead to phenomena of relevance to water security and sustainability. As such, most problems tackled by socio-hydrology involve some aspects of engineering design, such as large-scale water infrastructure, and self-organization in a broad context, such as cultural change at the population level and the hydrologic shift at the river basin or aquifer level. However, within the field of socio-hydrology, it has been difficult to find general theories …

Deep Learning For Screening Covid-19 Using Chest X-Ray Images, Sanhita Basu, Sushmita Mitra, Nilanjan Saha

ISI Best Publications

With the ever increasing demand for screening millions of prospective 'novel coronavirus' or COVID-19 cases, and due to the emergence of high false negatives in the commonly used PCR tests, the necessity for probing an alternative simple screening mechanism of COVID-19 using radiological images (like chest X-Rays) assumes importance. In this scenario, machine learning (ML) and deep learning (DL) offer fast, automated, effective strategies to detect abnormalities and extract key features of the altered lung parenchyma, which may be related to specific signatures of the COVID-19 virus. However, the available COVID-19 datasets are inadequate to train deep neural networks. Therefore, …

A Colonized Cop: Indigenous Exclusion And Youth Climate Justice Activism At The United Nations Climate Change Negotiations, Corrie Grosse, Brigid Mark

Environmental Studies Faculty Publications

Youth activists around the world are demanding urgent climate action from elected leaders. The annual United Nations climate change negotiations, known as COPs, are key sites of global organizing and hope for a comprehensive approach to climate policy. Drawing on participant observation and in-depth interviews at COP25 in 2019, this research examines youth climate activists’ priorities, frustrations and hopes for creating just climate policy. Youth are disillusioned with the COP process and highlight a variety of ways through which the COP perpetuates colonial power structures that marginalize Indigenous peoples and others fighting for justice. This is intersectional exclusion - the …

Neighborhood Air Quality Impact From Construction Site Emissions In Portland, Or, Lyndsey Boyle

Environmental Science and Management Professional Master's Project Reports

Research has shown that diesel particulate matter, including black carbon, is harmful to human health and has climate warming properties. Emissions from off-road engines, specifically construction, are a major source of diesel particulate matter in Portland, OR. There has been little done to manage the impact that construction has on local air quality. This project included a review of recent literature on the health and climate warming effects of particulate matter and black carbon, a modeling study to better understand what the major sources of diesel particulate matter are in Oregon, and a review of current research on construction site …

Hypervalent Iodine Compounds With Halogen-Containing And Phosphinate Ligands, Yakun Cao

Chemistry Theses and Dissertations

In modern organic chemistry, hypervalent (HV) iodine(III) compounds have been used widely as oxidizing agents but applications of λ³-iodanes in polymer and material chemistry is still underexplored. In the first project, a new series of heterocyclic HV iodine(III) compounds with I–Cl bonds and various substituents at the N atom were synthesized and successfully employed in the synthesis of highly branched polymers when added to mixtures of styrene and 1,4-divinylbenzene containing 10–80 mol% of the divinyl crosslinker, or even pure crosslinker. HV iodine(III) also can be utilized for polymer modification. HV iodine(III) compounds with fluorine-containing ligands (F, CF_{3 …}

1,9,10-Substituted Phenothiazine Derivatives With Strained Radical Cations And Use Thereof, Susan A. Odom, Chad Risko, Matthew D. Casselman, Corrine F. Elliott, Nuwan Harsha Attanayake, Subrahmanyam Modekrutti

Chemistry Faculty Patents

Compounds for use in a rechargeable battery are provided, including a compound according to the formula: (see patent for the formula)

wherein R₁ and R₉ are independently selected from the group consisting of H, alkyl, aryl, perfluoroaryl, perfluoroalkyl, alkylaryl, alkoxyaryl, alkylcarboxyl, aryl carbonyl, haloalkyl, perfluoroalkyl, glycols, haloaryl, a negative electrolyte, and a polymer, so long as when R₁ is H, R₉ is not H; and R₁₀ is selected from the group consisting of methyl, alkyl, aryl, alkylaryl, alkoxyaryl, alkylcarboxyl, aryl carbonyl, haloalkyl, perfluoroalkyl, perfluoroaryl, glycols, haloaryl, an oligomer, and a polymer.

7th Annual Sustainability Report, Saint Mary's College Of California

Sustainability Report

No abstract provided.

Processor Modules For The Classroom Development Of Physical Computers, Lakshmi Ongolu

Master’s Theses and Projects

Processors are present in almost all the electronic components available in the market now. As they perform trillions of operations per second and are complex internally. This project is to build building modules for students, who will be able to develop their own processor. The main idea is that this will help students to experience the detailed workflow of a processor and focus on design and development instead of spending time on wiring and soldering. Different components such as Program Counter, Instruction Register, Memory, Multiplexer, Adder and transceivers are designed and printed as individual modules on printed circuit boards (PCB’s). …

Controlling The Chaotic Motions Of An Airfoil With A Nonlinear Stiffness Using Closed-Loop Harmonic Parametric Excitation, Robert Bruce Alstrom

Faculty and Student Publications

The purpose of this research is to conduct a preliminary investigation into the possibility of suppressing the flutter and post-flutter (chaotic) responses of a two-dimensional self-excited airfoil with a cubic nonlinear stiffness (in torsion) and linear viscous damping via closed-loop harmonic parametric excitation. It was found that the initial configuration of the proposed control scheme caused the torsional/pitch dynamics to act as a nonlinear energy sink; as a result, it was identified that the mechanisms of vibration suppression are the resonance capture cascade and the short duration or isolated resonance capture. It is the isolated resonance capture that is responsible …

Bird Collision Mitigation Report Fall 2020, Alejandra Cohen, Brandon Trusler, Wade Wilson, Ian Mcwilliams

Sustainability Exchange

Bird Strike Mitigation Project Report for Sustainability Exchange, Washington University in St. Louis, Fall 2020

Esg Investing, Fall 2020, Juliet Kamau, Anthony Qiu, Brent Schiller, Raheem Williams, Ge Yu, Zixin Zhou

Sustainability Exchange

ESG Investing Project for Sustainability Exchange, Washington University in St. Louis, Fall 2020