Physical Sciences and Mathematics Commons^™

Non-Diffracting States At Exceptional Points, Cem Yuce, Hamidreza Ramezani

Physics and Astronomy Faculty Publications and Presentations

We propose to use exceptional points (EPs) to construct diffraction-free beam propagation and localized power oscillation in lattices. We specifically consider two systems to utilize EPs for diffraction-free beam propagation, one in synthetic gauge lattices and the other one, in unidirectionally coupled resonators where each resonator individually is capable of creating orbital angular momentum beams (OAM). In the second system, we introduce the concept of robust and tunable OAM beam propagation in discrete lattices. We show that one can create robust OAM beams in an arbitrary number of sites of a photonic lattice. Furthermore, we report power oscillation at the …

Environmental Drivers Of Mesophotic Echinoderm Assemblages Of The Southeastern Pacific Ocean, Ariadna Mecho, Boris Dewitte, Javier Sellanes, Simon Van Gennip, Erin E. Easton, Joao B. Gusmao

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

Mesophotic ecosystems (50–400 m depth) of the southeastern Pacific have rarely been studied because of the logistical challenges in sampling across this remote zone. This study assessed how oxygen concentrations and other environmental predictors explain variation in echinoderm assemblages at these mesophotic systems, where this group is among the predominant fauna. We compiled data on echinoderm taxa at 91 sampling stations, from historical and recent surveys (between 1950 and 2019), covering a longitudinal gradient of approximately 3,700 km along with the Nazca, Salas y Gómez, and Juan Fernández ridges. Uni- and multivariate model-based tools were applied to analyze the patterns …

Extending The Frequency Reach Of Pulsar Timing Array Based Gravitational Wave Search Without High Cadence Observations, Yan Wang, Soumya Mohanty, Zhoujian Cao

Physics and Astronomy Faculty Publications and Presentations

Gravitational wave (GW) searches using pulsar timing arrays (PTAs) are assumed to be limited by the typical average observational cadence of 1/(2 weeks) for a single pulsar to GW frequencies . 4 × 10−7 Hz. We show that this assumption is incorrect and that a PTA can detect signals with much higher frequencies, which are preserved in the data due to aliasing, by exploiting asynchronous observations from multiple pulsars. This allows an observation strategy that is scalable to future large-scale PTAs containing O(103) pulsars, enabled by the Five-hundred meter Aperture Spherical Telescope and the Square Kilometer Array, without requiring a …

Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov

Physics and Astronomy Faculty Publications and Presentations

Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200nm tetragonal BaTiO3 powder. CoFe2O4 …

Scalable, Cost-Efficient Synthesis And Properties Optimization Of Magnetoelectric Cobalt Ferrite/Barium Titanate Composites, Farnaz Safi Samghabadi, Long Chang, Mohammad Khodadadi, Karen S. Martirosyan, Dmitri Litvinov

Physics and Astronomy Faculty Publications and Presentations

Cobalt ferrite (CoFe2O4)/barium titanate (BaTiO3) particulate composites exhibiting high magnetoelectric coefficients were synthesized from low-cost commercial precursors using mechanical ball milling followed by high-temperature annealing. CoFe2O4 (20 nm–50 nm) and either cubic or tetragonal BaTiO3 nanoparticle powders were used for the synthesis. It was found that utilizing a 50nm cubic BaTiO3 powder as a precursor results in a composite with a magnetoelectric coupling coefficient value as high as 4.3 mV/Oe cm, which is comparable to those of chemically synthesized core–shell CoFe2O4–BaTiO3 nanoparticles. The microstructure of these composites is dramatically different from the composite synthesized using 200nm tetragonal BaTiO3 powder. CoFe2O4 …

Traveling Wave Phenomena In A Nonlocal Dispersal Predator-Prey System With The Beddington-Deangelis Functional Response And Harvesting, Zhihong Zhao, Yan Li, Zhaosheng Feng

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

This paper is devoted to studying the existence and nonexistence of traveling wave solution for a nonlocal dispersal delayed predator-prey system with the Beddington-DeAngelis functional response and harvesting. By constructing the suitable upper-lower solutions and applying Schauder's fixed point theorem, we show that there exists a positive constant c∗ such that the system possesses a traveling wave solution for any given c>c∗. Moreover, the asymptotic behavior of traveling wave solution at infinity is obtained by the contracting rectangles method. The existence of traveling wave solution for c=c∗ is established by means of Corduneanu's theorem. The nonexistence of traveling wave …

Heterocycles In The Treatment Of Neglected Tropical Diseases, Kush K. Maheshwari, Debasish Bandyopadhyay

Chemistry Faculty Publications and Presentations

Background: Neglected Tropical Diseases (NTDs) affect a huge population of the world and the majority of the victims belong to the poor community of the developing countries. Until now, the World Health Organization (WHO) has identified 20 tropical diseases as NTDs that must be addressed with high priority. However, many heterocyclic scaffolds have demonstrated potent therapeutic activity against several NTDs.

Objective: There are three major objectives: (1) To discuss the causes, symptoms, and current status of all the 20 NTDs; (2) To explore the available heterocyclic drugs, as well as their mechanisms of action (if known), that are being used …

Influence Of Land Use Intensity And Management On Arbuscular Mycorrhizal Fungi-Avocado Symbiosis, Pushpa Soti, Bulent Toprak, Nina De La Rosa, Krish Jayachandran

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

This study was done to assess the effect of soil disturbance on arbuscular mycorrhizal fungi spore abundance and root colonization in avocado (Persea americana Mill.). Rhizosphere soil and root samples of avocado were collected from different farms in south Florida and analyzed for degree of mycorrhizal colonization in roots, spore density and diversity in soil along with soil characteristics. There was significant difference in the soil characteristics among the different farms. Similarly, there was a significant difference in the degree of mycorrhizal colonization in the roots and the arbuscular mycorrhizal fungi spore morphotypes among different land use and management practices. …

Campus Carbon Footprint Study At A South Texas University, Monica Garcia, Christian Florez, Diego Lopez, Jongmin Kim, Maysam Pournik

Mechanical Engineering Faculty Publications and Presentations

A campus carbon footprint study was conducted at the University of Texas Rio Grande Valley, a Southern Texan university. This initiative was the school’s strategic plan to set a baseline for overall campus resource utilization status as well as to answer global requests to track and reduce campus greenhouse gas emissions and achieve greater sustainability on campus. For fiscal years of 2016 to 2018, an overall increase of campus carbon footprint was about 0.6%. The biggest increase was observed from sources owned or controlled by the school while the emissions associated with power usage decreased. The university’s carbon footprint was …

Covert Computation In Self-Assembled Circuits, Angel A. Cantu, Austin Luchsinger, Robert Schweller, Tim Wylie

Computer Science Faculty Publications and Presentations

Traditionally, computation within self-assembly models is hard to conceal because the self-assembly process generates a crystalline assembly whose computational history is inherently part of the structure itself. With no way to remove information from the computation, this computational model offers a unique problem: how can computational input and computation be hidden while still computing and reporting the final output? Designing such systems is inherently motivated by privacy concerns in biomedical computing and applications in cryptography. In this paper we propose the problem of performing “covert computation” within tile self-assembly that seeks to design self-assembly systems that “conceal” both the input …

Carbon Combustion Synthesis Of Janus-Like Particles Of Magnetoelectric Cobalt Ferrite And Barium Titanate, Carlos Trevino De Leo, Gamage Chamath Dannangoda, Mkhitar A. Hobosyan, J. T. Held, F. Safi Samghabadi, Mohammad Khodadadi, Dmitri Litvinov, K. A. Mkhoyan, Karen S. Martirosyan

Physics and Astronomy Faculty Publications and Presentations

Carbon combustion synthesis of oxides was applied for quick and energy efficient production of multiferroic composite of cobalt ferrite and barium titanate to form Janus-like particles matrix structure. The exothermic oxidation of carbon nanoparticles with an average size of 5 nm and a specific surface area of 110 m2/g generates a self-propagating thermal wave with peak temperature of up to 1000 °C. The thermal front rapidly propagates through the mixture of solid reactants (magnetic- CoFe2O4 and ferroelectric-BaTiO3) and results in localized hot-spot sintering of magneto-electric phases to form a nanocomposite structure. Carbon is not incorporated in the product and is …

Identifying Nitrogen Source And Seasonal Variation In A Black Mangrove (Avicennia Germinans) Communityof The South Texas Coast, Ashley Elizabeth Murphy, Carlos E. Cintra-Buenrostro, Alejandro Fierro-Cabo

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

Black mangrove (Avicennia germinans) stands in south Texas grow in association with other autotrophic organisms including herbaceous halophytes and cyanobacterial mats. Despite the relevant ecosystem services provided by this coastal plant community, limited information exists on its functioning, in particular as it pertains to nutrient dynamics, namely nitrogen (N). Nitrogen stable isotopes were used to assess potential N sources for plant growth in this community. Plant tissue (leaves), cyanobacteria, and sediment were sampled once every season for one year. Total N in A. germinans (2.6 %) and associated saltwort (Batis maritima) (2.1 %) was higher than in cyanobacteria (0.6 %), …

Global-In-Time Solvability And Blow-Up For A Non-Isospectral Two-Component Cubic Camassa-Holm System In A Critical Besov Space, Lei Zhang, Zhijun Qiao

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In this paper, we prove the global Hadamard well-posedness of strong solutions to a non-isospectral two-component cubic Camassa-Holm system in the critical Besov space B2,11/2(T). Our results show that in comparison with the well-known work for classic Camassa-Holm-type equations, the existence of global solution only relies on the L1-integrability of the variable coefficients α(t) and γ(t), but nothing to do with the shape of the initial data. The key ingredient of the proof hinges on the careful analysis of the mutual effect among two component forms, the uniform bound of approximate solutions, and several crucial estimates of cubic nonlinearities in …

Nuclear Niño Response Observed In Simulations Of Nuclear War Scenarios, Joshua Coupe, Samantha Stevenson, Nicole S. Lovenduski, Tyler Rohr, Cheryl S. Harrison, Alan Robock, Holly Olivarez, Charles G. Bardeen, Owen B. Toon

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

The climate impacts of smoke from fires ignited by nuclear war would include global cooling and crop failure. Facing increased reliance on ocean-based food sources, it is critical to understand the physical and biological state of the post-war oceans. Here we use an Earth system model to simulate six nuclear war scenarios. We show that global cooling can generate a large, sustained response in the equatorial Pacific, resembling an El Niño but persisting for up to seven years. The El Niño following nuclear war, or Nuclear Niño, would be characterized by westerly trade wind anomalies and a shutdown of equatorial …

A Multi-Modal Approach To Measuring Particulate Iron Speciation In Buoyant Hydrothermal Plumes, Brandy D. Stewart, Jeffry V. Sorensen, Kathleen Wendt, Jason B. Sylvan, Christopher R. German, Karthik Anantharaman, Gregory J. Dick, John A. Breier, Brandy M. Toner

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

Processes active within buoyant hydrothermal plumes are expected to modulate the flux of elements, such as Fe, to the deep ocean; however, they are yet to be described in a comprehensive manner through observations or models. In this study, we compare observed particulate Fe (pFe) speciation with thermodynamic (equilibrium) reaction path modeling for three vent fields in the Eastern Lau Spreading Center (ELSC). At each site, particles were collected from the buoyant rising portion of hydrothermal plumes using in situ filtration with a Remotely Operated Vehicle. Filter bound particles were analyzed by synchrotron micro-probe X-ray fluorescence mapping (XRF), X-ray diffraction …

Huygens' Principle For The Generalized Dirac Operator In Curved Spacetime, Karen Yagdjian

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In this article we give sufficient conditions for the generalized Dirac operator to obey the incomplete Huygens principle, as well as necessary and sufficient conditions to obey the Huygens principle by the Dirac operator in the curved spacetime of the Friedmann-Lemaître-Robertson-Walker models of cosmology.

Arithmetic Properties Of Septic Partition Functions, Timothy Huber, Mayra Huerta, Nathaniel Mayes

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Congruences and related identities are derived for a set of colored and weighted partition functions whose generating functions generate the graded algebra of integer weight modular forms of level seven. The work determines a general strategy for identifying and proving identities and associated congruences for modular forms on the principal congruence subgroup of level 7. Ramanujan's partition congruence modulo 7 serves as a prototype for the process used to prove new congruences for modular forms of level 7.

Co-Phosphorylation Networks Reveal Subtype-Specific Signaling Modules In Breast Cancer, Marzieh Ayati, Mark R. Chance, Mehmet Koyuturk

Computer Science Faculty Publications and Presentations

Motivation Protein phosphorylation is a ubiquitous mechanism of post-ranslational modification that plays a central role in cellular signaling. Phosphorylation is particularly important in the context of cancer, as down-regulation of tumor suppressors and up-regulation of oncogenes by the dysregulation of associated kinase and phosphatase networks are shown to have key roles in tumor growth and progression. Despite recent advances that enable large-scale monitoring of protein phosphorylation, these data are not fully incorporated into such computational tasks as phenotyping and subtyping of cancers.

Results We develop a network-based algorithm, CoPPNet, to enable unsupervised subtyping of cancers using phosphorylation data. For this …

Carbon Fibers Coated With Ternary Ni-Co-Se Alloy Particles As Low-Cost Counter Electrode For Flexible Dye Sensitized Solar Cell, Brishty Deb Choudhury, Chen Lin, Sk Md Ali Zaker Shawon, Javier Soliz-Martinez, Jose Gutierrez, Muhammad N. Huda, Federico Cesano, Karen Lozano, Jin Zhong Zhang, M. Jasim Uddin

Chemistry Faculty Publications and Presentations

Compared to flat devices based on rigid substrates, cable-shaped dye-sensitized solar cells hold advantages of smaller size, light weight, facile fabrication, flexibility, and low cost, thus a promising direction for applications such as wearable electronic devices. However, most reported fiber-shaped dye-sensitized solar cells use Pt wires as counter electrodes, which are high in cost. Herein, a flexible Pt-free counter electrode is fabricated via depositing ternary nickel cobalt selenide (Ni–Co–Se) particles on the surface of carbon fibers. Scanning electron microscopy and X-ray diffraction are used to characterize the counter electrode and alloy material. Results from bare and modified carbon fiber counter …

Contextual And Organizational Factors In Sustainable Supply Chain Decision-Making: Grey Relational Analysis And Interpretative Structural Modeling, Zhaojun Yang, Xiaoting Guo, Jun Sun, Yali Zhang

Information Systems Faculty Publications and Presentations

Sustainable supply chain emerges as a major business trend essential to long-term competitive advantage. Relevant corporate decisions concern a broad range of factors and require novel analytical models for critical control. This study conducts mathematical analyses to identify the factors that are vital yet receiving insufficient attention from researchers and practitioners. Valid survey observations were collected from 113 enterprises in China, the biggest emerging economy that faces the dilemma between development and sustainability. Grey relational analysis (GRA) and interpretative structural modeling (ISM) assess the importance levels of contextual and organizational factors and explore their joint effects. Validated with conventional expert …

Environmental Noise In Advanced Ligo Detectors, P. Nguyen, R. M. S. Schofield, A. Effler, C. Austin, V. B. Adya, M. Ball, S. Banagiri, K. Banowetz, C. Billman, Karla E. Ramirez

Physics and Astronomy Faculty Publications and Presentations

The sensitivity of the advanced LIGO detectors to gravitational waves can be affected by environmental disturbances external to the detectors themselves. Since the transition from the former initial LIGO phase, many improvements have been made to the equipment and techniques used to investigate these environmental effects. These methods have aided in tracking down and mitigating noise sources throughout the first three observing runs of the advanced detector era, keeping the ambient contribution of environmental noise below the background noise levels of the detectors. In this paper we describe the methods used and how they have led to the mitigation of …

Evaluating The Impacts Of Dam Construction And Longshore Transport Upon Modern Sedimentation Within The Rio Grande Delta (Texas, U.S.A.), Samantha Moore, Elizabeth A. Heise, Marty Grove, Anthony Reisinger, Jude A. Benavides

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

The modern Rio Grande delta system has experienced a century of dam construction, water removal for irrigation and municipal use, and land use modifications that have dramatically reduced its sediment load. This study examines whether damming has sufficiently limited delivery of upstream sediment to permit locally eroded sources and/or littoral transport along the coast to influence the provenance signal of the Rio Grande delta. Changes in sediment provenance within the Rio Grande’s delta can be detected and quantified by measurement of detrital zircon Uranium–lead dating age distributions. Previous provenance studies indicate that modern Rio Grande river sand upstream of Falcon …

Edsc: An Event-Driven Smart Contract Platform, Mudabbir Kaleem, Keshav Kasichainula, Rabimba Karanjai, Lei Xu, Zhimin Gao, Lin Chen, Weidong Shi

Computer Science Faculty Publications and Presentations

This paper presents EDSC, a novel smart contract platform design based on the event-driven execution model as opposed to the traditionally employed transaction-driven execution model. We reason that such a design is a better fit for many emerging smart contract applications and is better positioned to address the scalability and performance challenges plaguing the smart contract ecosystem. We propose EDSC’s design under the Ethereum framework, and the design can be easily adapted for other existing smart contract platforms. We have conducted implementation using Ethereum client and experiments where performance modeling results show on average 2.2 to 4.6 times reduced total …

Sentiment Analysis Of Long-Term Social Data During The Covid-19 Pandemic, Sophanna Ek, Marco Curci, Xiaokun Yang, Beiyu Lin, Pinchao Liu, Hailu Xu

Computer Science Faculty Publications and Presentations

The COVID-19 pandemic has bringing the “infodemic” in the social media worlds. Various social platforms play a significant role in instantly acquiring the latest updates of the pandemic. Social media such as Twitter and Facebook produce vast amounts of posts related to the virus, vaccines, economics, and politics. In order to figure out how public opinion and sentiments are expressed during the pandemic, this work analyzes the long-term social posts from social media and conducts sentiment analysis on tweets within 12 months. Our findings show the trend topics of long-term social communities during the pandemic and express people’s attitudes towards …

Covert Computation In Staged Self-Assembly: Verification Is Pspace-Complete, David Caballero, Timothy Gomez, Robert Schweller, Tim Wylie

Computer Science Faculty Publications and Presentations

Staged self-assembly has proven to be a powerful abstract model of self-assembly by modeling laboratory techniques where several nanoscale systems are allowed to assemble separately and then be mixed at a later stage. A fundamental problem in self-assembly is Unique Assembly Verification (UAV), which asks whether a single final assembly is uniquely constructed. This has previously been shown to be Π^{p}₂-hard in staged self-assembly with a constant number of stages, but a more precise complexity classification was left open related to the polynomial hierarchy.
Covert Computation was recently introduced as a way to compute a function while hiding the input …

New Amphibian And Reptile Distribution Records From Eastern South Dakota, Usa, Drew R. Davis

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

Over recent years, the continued collection of voucher specimens has helped to better document the distributions of South Dakota’s amphibians and reptiles. Despite large increases in our knowledge of these distributions, it remains clear that gaps in our understanding remain. Here, I report 17 new county records of six species of amphibians and reptiles from eastern South Dakota (east of the Missouri River) that are the result of fieldwork conducted in September 2020. The majority of these records are from the northern portions of the James River Lowland, Missouri Coteau, and Drift Plains ecoregions (Bryce et al. 1998), which are …

Agn Jets And A Fanciful Trio Of Black Holes In The Abell 85 Brightest Cluster Galaxy, Juan P. Madrid

Physics and Astronomy Faculty Publications and Presentations

A new radio map of the Abell 85 Brightest Cluster Galaxy (BCG) was obtained with the Karl G. Jansky Very Large Array. With a resolution of 002, this radio image shows two kiloparsec-scale bipolar active galactic nucleus jets emanating from the active galactic nucleus of the A85 BCG. The galaxy core appears as a single entity on the new radio map. It has been assumed that the A85 BCG contained a binary black hole in its core. However, Chandra X-ray data and the new high-resolution radio map show no evidence that the A85 BCG harbors a binary black hole. The …

Enhancing Student Learning In Introductory Physics Through Funds Of Knowledge, Liang Zeng, Guang Zeng

Physics and Astronomy Faculty Publications and Presentations

Researchers have reported the funds of knowledge (FK) pedagogical approach effective in engaging minority students in learning. However, there are a lack of studies connecting FK to introductory college physics or physical science classes. By using examples from regional Mexican-American lived experiences at an Hispanic-serving institution located along the recently politicized U.S.-Mexico border, this paper provides evidence to show how physics educators can use FK to engage students in learning introductory college physics concepts.

Reducing Scattered Light In Ligo's Third Observing Run, S. Soni, C. Austin, A. Effler, R. M. S. Schofield, G. Gonzalez, V. V. Frolov, J. C. Driggers, A. Pele, A. L. Urban, G. Valdes, K. E. Ramirez

Physics and Astronomy Faculty Publications and Presentations

Noise due to scattered light has been a frequent disturbance in the advanced LIGO gravitational wave detectors, hindering the detection of gravitational waves. The non stationary scatter noise caused by low frequency motion can be recognized as arches in the time-frequency plane of the gravitational wave channel. In this paper, we characterize the scattering noise for LIGO and Virgo's third observing run O3 from April, 2019 to March, 2020. We find at least two different populations of scattering noise and we investigate the multiple origins of one of them as well as its mitigation. We find that relative motion between …

Pint: A Modern Software Package For Pulsar Timing, Jing Luo, S. M. Ransom, Paul B. Demorest, P. S. Ray, Anne M. Archibald, M. Kerr, Ross J. Jennings, Matteo Bachetti, Rutger Van Haasteren, Fredrick A. Jenet

Physics and Astronomy Faculty Publications and Presentations

Over the past few decades, the measurement precision of some pulsar timing experiments has advanced from ~10 μs to ~10 ns, revealing many subtle phenomena. Such high precision demands both careful data handling and sophisticated timing models to avoid systematic error. To achieve these goals, we present PINT (PINT Is Not Tempo3), a high-precision Python pulsar timing data analysis package, which is hosted on GitHub and available on the Python Package Index (PyPI) as pint-pulsar. PINT is well tested, validated, object oriented, and modular, enabling interactive data analysis and providing an extensible and flexible development platform for timing applications. …