Physical Sciences and Mathematics Commons^™

Experimental Testing Of A 3d-Printed Metamaterial Slow Wave Structure For High Power Microwave Generation, Antonio B. De Alleluia

Electrical and Computer Engineering ETDs

A metamaterial (MTM) high power microwave (HPM) vacuum electron device (VED) was developed using 3D printing technology. The specific geometric pattern of the source can produce both negative permittivity and permeability to interact with a relativistic electron beam. The electron beam is generated using a pulsed electron accelerator with a maximum energy of 700 keV and lasting approximately 16 ns. The design of this novel VED consists of a circular waveguide loaded with complementary split-ring resonators in a linear periodic arrangement in which the relativistic beam travels guided by a magnetic field. The electrons interact with the MTM producing electromagnetic …

Melissa: System Description And Spectral Features Of Pre- And Post-Midnight F-Region Echoes, Fabiano S. Rodrigues, Weijia Zhan, Marco A. Milla, B. G. Fejer, Eurico R. De Paula, Acacio C. Neto, Angela M. Santos, Inez S. Batista

All Physics Faculty Publications

Most of the low‐latitude ionospheric radar observations in South America come from the Jicamarca Radio Observatory, located in the western longitude sector (∼75°W). The deployment of the 30 MHz FAPESP‐Clemson‐INPE (FCI) coherent backscatter radar in the magnetic equatorial site of São Luis, Brazil, in 2001 allowed observations to be made in the eastern sector (∼45°W). However, despite being operational for several years (2001–2012), FCI only made observations during daytime and pre‐midnight hours, with a few exceptions. Here, we describe an upgraded system that replaced the FCI radar and present results of full‐night F‐region observations. This radar is referred to …

The Experiences Of African American Male Computer Science Majors In Two Year Colleges, Simone Brookins Jenkins

USF Tampa Graduate Theses and Dissertations

As the field of computer science grows and the computing science workforce demands more qualified workers, the United States workforce will require underrepresented minorities to help meet these demands. African American males are a demographic that can help meet this need but there are few of them pursuing computer science careers and successfully graduating with computer science degrees. The purpose of this qualitative study was to examine the experiences of African American male two-year college students who are in pursuit of a degree in computer science. My findings indicated that the study participants’ experiences such as positive interactions with faculty …

Smooth Flow In Diamond: Atomistic Ductility And Electronic Conductivity, Chang Liu, Xianqi Song, Quan Li, Yanming Ma, Changfeng Chen

Physics & Astronomy Faculty Research

Diamond is the quintessential superhard material widely known for its stiff and brittle nature and large electronic band gap. In stark contrast to these established benchmarks, our first-principles studies unveil surprising intrinsic structural ductility and electronic conductivity in diamond under coexisting large shear and compressive strains. These complex loading conditions impede brittle fracture modes and promote atomistic ductility, triggering rare smooth plastic flow in the normally rigid diamond crystal. This extraordinary structural change induces a concomitant band gap closure, enabling smooth charge flow in deformation created conducting channels. These startling soft-and-conducting modes reveal unprecedented fundamental characteristics of diamond, with profound …

A New Algorithm For Primer Design, Debanjan Guha Roy

Electronic Thesis and Dissertation Repository

The Polymerase Chain Reaction (PCR) technology is widely used to create DNA copies. It has impacted many diverse fields including genetics, forensics, molecular paleontology, medical applications and environmental microbiology.

The main object in PCR is a primer, a short single strand of DNA, about 18-25 bases long, that serves as the starting point of DNA synthesis. Primers are essential for DNA replication because the enzymes that catalyze this process, DNA polymerases, can only add new nucleotides to an existing strand of DNA. The PCR starts at the 3’-end of the primer and copies the opposite strand.Designing good primers is essential …

How Good Are Standard Copulas Anyway?, Dragan Radulovic

Mathematics Colloquium Series

First, we will raise a question: How good are standard copulas in capturing the dependency structure? To this end we will offer a series of simulated/numerical examples demonstrating that, more often than not, standard model copulas do not capture the underlying dependency structure. We believe that copula models, unlike other statistical tools, are too readily accepted by practitioners. Rigorous, goodness-of-fit tests are commonly replaced by off-hand statements like: “it works well”. To this end, the second part of the talk offers a theoretical result, an umbrella type theorem tailored for creating numerous Goodness of Fit tests for copulas.

Structure-Property-Function Connections Underlying Performance Of Polybenzoxazole Membranes Derived From Bisapaf Polyimides, Maram A. Q. Al-Sayaghi, Jeremy Lewis, Chris Buelke, Ali Alshami

Chemical Engineering Faculty Publications

Highlights

• Stable rigid monomers result in polyimides with higher Mw, Tg, TR, and the more superior separation performance.
• Thermal rearrangement improved ideal gas separation by 1.5 to 2.0 orders of magnitude.
• Thermal rearrangement resulted in an enhanced thermal, mechanical and chemical properties of the produced membranes.

Polymeric membranes remain and will most likely continue to be the most practical cost-effect chemical constructs for gas separation processes, provided that novel polymers are developed to overcome current and persisting limitations facing exiting membranes. Here, we report a methodical and systematic study of the structure-property-function relations of standard polyimide membranes and their implications …

Weather And Climate Summary And Forecast: November 2019 Report, Gregory V. Jones

Linfield University Wine Studies Reports

This report provides a summary of the weather and climate forecast for November 2019. It includes forecast information specific to the Pacific Northwest and the western United States, as well as forecast information for other portions of the United States and abroad.

Soil Aggregates As A Source Of Dissolved Organic Carbon To Streams: An Experimental Study On The Effect Of Solution Chemistry On Water Extractable Carbon, Malayika M. Cincotta, Julia N. Perdrial, Aaron Shavitz, Arianna Libenson, Maxwell Landsman-Gerjoi, Nicolas Perdrial, Jesse Armfield, Thomas Adler, James B. Shanley

College of Arts and Sciences Faculty Publications

Over the past two decades, headwater streams of the northern hemisphere have shown increased amounts of dissolved organic carbon (DOC), coinciding with decreased acid deposition. The exact nature of the mechanistic link between precipitation composition and stream water DOC is still widely debated in the literature. We hypothesize that soil aggregates are the main source of stream water DOC and that DOC release is greater in organic rich, riparian soils vs. hillslope soils. To test these hypotheses, we collected soils from two main landscape positions (hillslope and riparian zones) from the acid-impacted Sleepers River Research Watershed in northeastern Vermont. We …

Planck's And Callendar's Blackbody Radiation Formulas And Their Fitness To Experimental Data, Max Tran

Publications and Research

In this paper, we compare the blackbody radiation density formula obtained with classical physics by Hugh L Callendar and the formula obtained by Max Planck using quantization of energy. We use R and Maxima to analyze their fitness on coordinating experimental data and indicate some limitations with experiments in this area.

Why The Crackling Deformations Of Single Crystals, Metallic Glasses, Rock, Granular Materials, And The Earth’S Crust Are So Surprisingly Similar, Karin A. Dahmen, Jonathan T. Uhl, Wendelin J. Wright

Faculty Journal Articles

Recent experiments show that the deformation properties of a wide range of solid materials are surprisingly similar. When slowly pushed, they deform via intermittent slips, similar to earthquakes. The statistics of these slips agree across vastly different structures and scales. A simple analytical model explains why this is the case. The model also predicts which statistical quantities are independent of the microscopic details (i.e., they are "universal"), and which ones are not. The model provides physical intuition for the deformation mechanism and new ways to organize experimental data. It also shows how to transfer results from one scale to another. …

Charging And Supercharging Of Proteins For Mass Spectrometry: Recent Insights Into The Mechanisms Of Electrospray Ionization., Lars Konermann, Haidy Metwally, Quentin Duez, Insa Peters

Chemistry Publications

Electrospray ionization (ESI) is an essential technique for transferring proteins from solution into the gas phase for mass spectrometry and ion mobility spectrometry. The mechanisms whereby [M + zH]^z+ protein ions are released from charged nanodroplets during ESI have been controversial for many years. Here we discuss recent computational and experimental studies that have shed light on many of the mysteries in this area. Four types of protein ESI experiments can be distinguished, each of which appears to be associated with a specific mechanism. (i) Native ESI proceeds according to the charged residue model (CRM) that entails droplet evaporation …

Stretchable Self-Healable Semiconducting Polymer Film For Active-Matrix Strain-Sensing Array, Jin Young Oh, Donghee Son, Toru Katsumata, Yeongjun Lee, Yeongin Kim, Jeffrey Lopez, Hung-Chin Wu, Jiheong Kang, Joonsuk Park, Xiaodan Gu, Jaewan Mun, Nathan Ging-Ji Wang, Yikai Yin, Wei Cai, Youngjun Yun, Jeffrey B.-H. Tok, Zhenan Bao

Faculty Publications

Skin-like sensory devidces shoud be stretchable and self-healable to meet the demands for future electronic skin applications. Despite recent notable advances in skin-inspired electronic materials, it remains challenging to confer these desired functionalities to an active semiconductor. Here, we report a strain-sensitive, stretchable, and autonomously self-healable semiconducting film achieved through blending of a polymer semiconductor and a self-healable elastomer, both of which are dynamically cross-linked by metal coordination. We observed that by controlling the percolation threshold of the polymer semiconductor, the blend film became strain sensitive, with a gauge factor of 5.75 x 10⁵ at 100% strain in a …

Investigations Of Aerobic Methane Oxidation In Two Marine Seep Environments: Part 2—Isotopic Kinetics, Eric W. Chan, Allan M. Shiller, Dongjoo J. Joung, Eleanor C. Arrington, David L. Valentine, Molly C. Redmond, John A. Breier, Scott A. Socolofsky, John D. Kessler

School of Earth, Environmental, and Marine Sciences Faculty Publications and Presentations

During aerobic oxidation of methane (CH4) in seawater, a process which mitigates atmospheric emissions, the 12C‐isotopologue reacts with a slightly greater rate constant than the 13C‐isotopologue, leaving the residual CH4 isotopically fractionated. Prior studies have attempted to exploit this systematic isotopic fractionation from methane oxidation to quantify the extent that a CH4 pool has been oxidized in seawater. However, cultivation‐based studies have suggested that isotopic fractionation fundamentally changes as a microbial population blooms in response to an influx of reactive substrates. Using a systematic mesocosm incubation study with recently collected seawater, here we investigate the fundamental isotopic kinetics of aerobic …

Recommendation-Based Team Formation For On-Demand Taxi-Calling Platforms, Lingyu Zhang, Tianshu Song, Yongxin Tong, Zimu Zhou, Dan Li, Wei Ai, Lulu Zhang, Guobin Wu, Yan Liu, Jieping Ye

Research Collection School Of Computing and Information Systems

On-demand taxi-calling platforms often ignore the social engagement of individual drivers. The lack of social incentives impairs the work enthusiasms of drivers and will affect the quality of service. In this paper, we propose to form teams among drivers to promote participation. A team consists of a leader and multiple members, which acts as the basis for various group-based incentives such as competition. We define the Recommendation-based Team Formation (RTF) problem to form as many teams as possible while accounting for the choices of drivers. The RTF problem is challenging. It needs both accurate recommendation and coordination among recommendations, since …

Using Customer Service Dialogues For Satisfaction Analysis With Context-Assisted Multiple Instance Learning, Kaisong Song, Lidong Bing, Wei Gao, Jun Lin, Lujun Zhao, Jiancheng Wang, Changlong Sun, Xiaozhong Liu, Qiong Zhang

Research Collection School Of Computing and Information Systems

Customers ask questions and customer service staffs answer their questions, which is the basic service model via multi-turn customer service (CS) dialogues on E-commerce platforms. Existing studies fail to provide comprehensive service satisfaction analysis, namely satisfaction polarity classification (e.g., well satisfied, met and unsatisfied) and sentimental utterance identification (e.g., positive, neutral and negative). In this paper, we conduct a pilot study on the task of service satisfaction analysis (SSA) based on multi-turn CS dialogues. We propose an extensible Context-Assisted Multiple Instance Learning (CAMIL) model to predict the sentiments of all the customer utterances and then aggregate those sentiments into service …

Co2 Levels And Climate Change During Early Eocene Hyperthermals, Ying Cui

Ying Cui

Early Eocene (56 to 33.9 million years ago) is punctuated by a series of rapid and extreme global warming events, known as the ‘hyperthermals’, triggered by massive release of carbon dioxide. Despite the carbon emission rate might have been ten times smaller than the current emission from burning fossil fuels and cement production, the early Eocene hyperthermals are considered one of the best analogues for CO2 concentration projected into the future. The temperature records are well established from deep sea sediments during these hyperthermals, but the CO2 levels in the atmosphere remain poorly known, partly due to the lack of …

Marine Sediment Record From The East Antarctic Margin Reveals Dynamics Of Ice Sheet Recession, Amy Leventer, Eugene Domack, Jennifer Pike, Catherine Stickley, Eleanor Maddison, Stefanie A. Brachfeld, Patricia Manley, Charlie Mcclennen

Stefanie Brachfeld

The Antarctic shelf is traversed by large-scale troughs developed by glacial erosion. Swath bathymetric, lithologic, and chronologic data from jumbo piston cores from four sites along the East Antarctic margin (Iceberg Alley, the Nielsen Basin, the Svenner Channel, and the Mertz-Ninnis Trough) are used to demonstrate that these cross-shelf features controlled development of calving bay reentrants in the Antarctic ice sheet during deglaciation. At all sites except the Mertz-Ninnis Trough, the transition between the Last Glacial Maximum and the Holocene is characterized by varved couplets deposited during a short interval of extremely high primary productivity in a fjordlike setting. Nearly …

Redundancy Effect Of Vehicular Cloud’S Environment Using Location Estimate (Revise), Mohamed El-Tawab, Samy El-Tawab, M. Hossain Heydari

Showcase of Graduate Student Scholarship and Creative Activities

The rapid growth of modern wireless technology increases the invention of new applications using the concept of Internet of Things (IoT). Vehicular Cloud, which is a concept introduced recently to use the vehicles sitting idle for hours as a processing devices, has been a hot topic. This subject became more popular after the Department of Transportation’s (DOT) announcement of mandatory wireless capabilities of each vehicle since 2015. We investigate the idea of benefiting from the unused processing power of vehicles sitting in parking lots for a long period of time (e.g. an airport, or train station). Moreover, researchers propose the …

Properties Of New York/New Jersey Harbor Sediments, K. W. Jones, Huan Feng, E. A. Stren, U. Neuhäusler, J. Osán, N. Marinkovic, Z. Song

Huan Feng

Sediments found in waterways around the world may contain toxic compounds of anthropogeilic origin that can harm the environment and human health. As a result, it is often necessary to remove them and find disposal methods that are environmentally and economically acceptable. Here, we report on results obtained in an experimental program to characterize the nature of the sediment contamination. The objective was to gain a better understanding of the properties of the sediments to develop better methods for understanding the fate and transport of the contaminants and for improving methods for their removal from the sediments. Our investigations made …

Urban Environmental Pollution 2010: Trace Metal Dispersion In Soil From Auto-Mechanic Village To Urban Residential Areas In Owerri, Nigeria, Michael A. Nwachukwu, Huan Feng, Jude Alinnor

Huan Feng

Due to poor waste management in mechanic villages (MVs), average metal concentration (mgkg-1) is Pb 1162±572; Mn 864±531; Cu 385±202; Fe 49259±4770; Cd 20±13; Zn 824±190; and Ni 40±35, causing ecological and public health risks in parts of Nigeria. Average metal dispersion (mgkg-1/m) from MVs to residential areas was estimated at 9.2 for Pb; 6.7 for Mn; 6.1 for Zn; 1.5 for Cu; 197 for Fe; 0.3 for Ni; and 0.04 for Cd. This represents a mobility order of Fe>Pb>Mn>Zn>Cu>Ni>Cd, and a pollution order of Pb>Ni>Mn>Zn>Fe>Cu>Cd. MV advantages …

Magnetic Mineral Diagenesis In The River‐Dominated Inner Shelf Of The East China Sea, China, Can Ge, Weiguo Zhang, Chenyin Dong, Yan Dong, Jinyan Liu, Nguyen Thi Thu Hien, Huan Feng, Lizhong Yu

Huan Feng

The inner shelf of the East China Sea is a river-dominated margin characterized by fine-grained mud deposits and a rapid sedimentation rate. Three short sediment cores (similar to 2.7m in length) were examined to characterize spatial variations in magnetic mineral diagenesis. The sediment cores were analyzed for sedimentation rates, magnetic properties, particle size distribution, organic carbon, and total sulfur content. The two more proximal cores with higher sedimentation rates (similar to 2.2cm/yr and similar to 0.96cm/yr) do not exhibit obvious effects of reductive dissolution of magnetite with increasing depth, which is consistent with their lower total sulfur content. The offshore …

Evidence For Exocellular Arsenic In Fronds Of Pteris Vittata, Rupali Datta, Padmini Das, Ryan Tappero, Pravin Punamiya, Evert Elzinga, Shivendra Sahi, Huan Feng, Jeffrey Kiiskila, Dibyendu Sarkar

Huan Feng

The arsenic (As) hyperaccumulating fern species Pteris vittata (PV) is capable of accumulating large quantities of As in its aboveground tissues. Transformation to AsIII and vacuolar sequestration is believed to be the As detoxification mechanism in PV. Here we present evidence for a preponderance of exocellular As in fronds of Pteris vittata despite numerous reports of a tolerance mechanism involving intracellular compartmentalization. Results of an extraction experiment show that 43–71% of the As extruded out of the fronds of PV grown in 0.67, 3.3 and 6.7mM AsV. SEM-EDX analysis showed that As was localized largely on the lower pinna surface, …

Enhancing Digestibility And Ethanol Yield Of Populus Wood Via Expression Of An Engineered Monolignol 4-O-Methyltransferase, Yuanheng Cai, Kewei Zhang, Hoon Kim, Guichuan Hou, Xuebin Zhang, Huijun Yang, Huan Feng, Lisa Miller, John Ralph, Chang-Jun Liu

Huan Feng

Producing cellulosic biofuels and bio-based chemicals from woody biomass is impeded by the presence of lignin polymer in the plant cell wall. Manipulating the monolignol biosynthetic pathway offers a promising approach to improved processability, but often impairs plant growth and development. Here, we show that expressing an engineered 4-O-methyltransferase that chemically modifies the phenolic moiety of lignin monomeric precursors, thus preventing their incorporation into the lignin polymer, substantially alters hybrid aspens’ lignin content and structure. Woody biomass derived from the transgenic aspens shows a 62% increase in the release of simple sugars and up to a 49% increase in the …

Sustainable Solutions, Fall/Winter 2020, Issue 41

Sustain Magazine

No abstract provided.

Performance Of Concrete Made With A Calcined Clay – Limestone-Portland Cement Exposed To Natural Conditions, Fernando Martirena, Ernesto Díaz, Dayran Rocha, Hamed Maraghechi, Karen Louise Scrivener

International Conference on Durability of Concrete Structures

This work presents the results of an investigation carried out to assess durability of concrete made with a calcined clay- limestone-Portland cement with 47% of clinker, hereafter named LC3, produced during an industrial trial in 2013. LC3 was used to cast concrete blocks and later expose them at a natural location at the northern coast of Cuba. Reference concrete was cast with Cuban Portland cement having 88% of clinker. Throughout three years (2015, 2016, 2017) concrete cores were systematically taken and the specimens were subjected to a testing program that included Formation factor, chloride profiling, surface resistivity, air permeability and …

Virtual Wrap-Up Presentation: Digital Libraries, Intelligent Data Analytics, And Augmented Description, Elizabeth Lorang, Leen-Kiat Soh, Yi Liu, Chulwoo Pack

CSE Conference and Workshop Papers

Includes framing, overview, and discussion of the explorations pursued as part of the Digital Libraries, Intelligent Data Analytics, and Augmented Description demonstration project, pursued by members of the Aida digital libraries research team at the University of Nebraska-Lincoln through a research services contract with the Library of Congress. This presentation covered: Aida research team and background for the demonstration project; broad outlines of “Digital Libraries, Intelligent Data Analytics, and Augmented Description”; what changed for us as a research team over the collaboration and why; deliverables of our work; thoughts toward “What next”; and deep-dives into the explorations. The machine learning …

Habitat Associations And Reproduction Of Fishes On The Northwestern Gulf Of Mexico Shelf Edge, Elizabeth Marie Keller

LSU Doctoral Dissertations

Several of the northwestern Gulf of Mexico (GOM) shelf-edge banks provide critical hard bottom habitat for coral and fish communities, supporting a wide diversity of ecologically and economically important species. These sites may be fish aggregation and spawning sites and provide important habitat for fish growth and reproduction. Already designated as habitat areas of particular concern, many of these banks are also under consideration for inclusion in the expansion of the Flower Garden Banks National Marine Sanctuary. This project aimed to gain a more comprehensive understanding of the communities and fish species on shelf-edge banks by way of gonad histology, …

Wcu Study Abroad And Carbon Offsets: Not Whether But Whxen Now!, Paul Sylvester

Sustainability Research & Practice Seminar Presentations

No abstract provided.

Topological Markers For Subcellular Chemical Mapping Using Tof-Sims, Anthony Castellanos

FIU Electronic Theses and Dissertations

Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is a powerful mass spectrometry imaging technique that is uniquely suited to the study of small and challenging biological samples. Mass spectrometry imaging permits the simultaneous detection of chemical species without a priori knowledge of a sample. In the present work, the use of endogenous chemical species, three-dimensional dual-beam depth profiling, and multi-modal mass spectrometry approaches are utilized to increase the specificity and reliability of sub-cellular chemical assignments. In addition, the use of these complimentary indicators serve as useful quality controls to ensure optimal preparation of samples for a high-vacuum environment. In the study …