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University of Texas Rio Grande Valley

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Articles 751 - 780 of 2419

Full-Text Articles in Physical Sciences and Mathematics

Hidden Treasures In The Unknown 3cr Extragalactic Radio Sky: A Multiwavelength Approach, V. Missaglia, F. Massaro, E. Liuzzo, A. Paggi, R. P. Kraft, W. R. Forman, A. Jimenez-Gallardo, Juan P. Madrid, F. Ricci, C. Stuardi Jul 2021

Hidden Treasures In The Unknown 3cr Extragalactic Radio Sky: A Multiwavelength Approach, V. Missaglia, F. Massaro, E. Liuzzo, A. Paggi, R. P. Kraft, W. R. Forman, A. Jimenez-Gallardo, Juan P. Madrid, F. Ricci, C. Stuardi

Physics and Astronomy Faculty Publications and Presentations

We present the analysis of multiwavelength observations of seven extragalactic radio sources, listed as unidentified in the Third Cambridge Revised Catalog (3CR). X-ray observations, performed during Chandra Cycle 21, were compared to Very Large Array (VLA), Wide-field Infrared Survey Explorer, and Pan-STARRS observations in the radio, infrared, and optical bands, respectively. All sources in this sample lack a clear optical counterpart, and are thus missing their redshift and optical classification. In order to confirm the X-ray and infrared radio counterparts of core and extended components, here we present for the first time radio maps obtained manually reducing VLA archival data. …

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From Reaction Kinetics To Dementia: A Simple Dimer Model Of Alzheimer’S Disease Etiology, Michael R. Lindstrom, Manuel B. Chavez, Elijah A. Gross-Sable, Eric Y. Hayden, David B. Teplow Jul 2021

From Reaction Kinetics To Dementia: A Simple Dimer Model Of Alzheimer’S Disease Etiology, Michael R. Lindstrom, Manuel B. Chavez, Elijah A. Gross-Sable, Eric Y. Hayden, David B. Teplow

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Oligomers of the amyloid β-protein (Aβ) have been implicated in the pathogenesis of Alzheimer’s disease (AD) through their toxicity towards neurons. Understanding the process of oligomerization may contribute to the development of therapeutic agents, but this has been difficult due to the complexity of oligomerization and the metastability of the oligomers thus formed. To understand the kinetics of oligomer formation, and how that relates to the progression of AD, we developed models of the oligomerization process. Here, we use experimental data from cell viability assays and proxies for rate constants involved in monomerdimer-trimer kinetics to develop a simple mathematical model …

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Protistan Grazing Impacts Microbial Communities And Carbon Cycling At Deep-Sea Hydrothermal Vents, Sarah K. Hu, Erica L. Herrera, Amy R. Smith, Maria G. Pachiadaki, Virginia P. Edgcomb, Sean P. Sylva, Eric W. Chan, Jeffrey S. Seewald, Christopher R. German, Julie A. Huber Jul 2021

Protistan Grazing Impacts Microbial Communities And Carbon Cycling At Deep-Sea Hydrothermal Vents, Sarah K. Hu, Erica L. Herrera, Amy R. Smith, Maria G. Pachiadaki, Virginia P. Edgcomb, Sean P. Sylva, Eric W. Chan, Jeffrey S. Seewald, Christopher R. German, Julie A. Huber

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

Microbial eukaryotes (or protists) in marine ecosystems are a link between primary producers and all higher trophic levels, and the rate at which heterotrophic protistan grazers consume microbial prey is a key mechanism for carbon transport and recycling in microbial food webs. At deep-sea hydrothermal vents, chemosynthetic bacteria and archaea form the base of a food web that functions in the absence of sunlight, but the role of protistan grazers in these highly productive ecosystems is largely unexplored. Here, we pair grazing experiments with a molecular survey to quantify protistan grazing and to characterize the composition of vent-associated protists in …

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Comparative Study Of Leachate Characterization: Implication For Sustainable Environmental Management, Osakpolor Marvellous Omorogieva, Victory Itua Igberase Jul 2021

Comparative Study Of Leachate Characterization: Implication For Sustainable Environmental Management, Osakpolor Marvellous Omorogieva, Victory Itua Igberase

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

Understanding the sources of environmental stressors, the role of geology, climate and technology would provide a guide to solving the problems posed by such stressor. The study examine the sources of wastes in Ikhueniro open dumpsite located in Benin city, Nigeria and characterize the leachate emanating from it. This will assist in adequate design of managerial scheme to tackle the menace posed by it while putting into consideration the role of geology, climate and technology. The key objectives are to carry out field study, characterize wastes in the dumpsite and collect raw leachate emanating from the wastes heap in order …

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Search For Gravitational Waves Associated With Gamma-Ray Bursts Detected By Fermi And Swift During The Ligo–Virgo Run O3a, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Amit Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, P. K. Roy, W. H. Wang Jul 2021

Search For Gravitational Waves Associated With Gamma-Ray Bursts Detected By Fermi And Swift During The Ligo–Virgo Run O3a, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Amit Aich, G. Bissenbayeva, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, P. K. Roy, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We search for gravitational-wave transients associated with gamma-ray bursts (GRBs) detected by the Fermi and Swift satellites during the first part of the third observing run of Advanced LIGO and Advanced Virgo (2019 April 1 15:00 UTC–2019 October 1 15:00 UTC). A total of 105 GRBs were analyzed using a search for generic gravitational-wave transients; 32 GRBs were analyzed with a search that specifically targets neutron star binary mergers as short GRB progenitors. We find no significant evidence for gravitational-wave signals associated with the GRBs that we followed up, nor for a population of unidentified subthreshold signals. We consider several …

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Resolving Galactic Binaries In Lisa Data Using Particle Swarm Optimization And Cross-Validation, Xue-Hao Zhang, Soumya Mohanty, Xiao-Bo Zou, Yu-Xiao Liu Jul 2021

Resolving Galactic Binaries In Lisa Data Using Particle Swarm Optimization And Cross-Validation, Xue-Hao Zhang, Soumya Mohanty, Xiao-Bo Zou, Yu-Xiao Liu

Physics and Astronomy Faculty Publications and Presentations

The space-based gravitational wave detector Laser Interferometric Space Antenna is expected to observe signals from a large population of compact object binaries, comprised predominantly of white dwarfs, in the Milky Way. Resolving individual sources from this population against its self-generated confusion noise poses a major data analysis problem. We present an iterative source estimation and subtraction method to address this problem based on the use of particle swarm optimization (PSO). In addition to PSO, a novel feature of the method is the cross-validation of sources estimated from the same data using different signal parameter search ranges. This is found to …

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Assessing Climate Change Impacts On Live Fuel Moisture And Wildfire Risk Using A Hydrodynamic Vegetation Model, Wu Ma, Lu Zhai, Alexandria Pivovaroff, Jacquelyn Shuman, Polly Buotte, Junyan Ding, Bradley O. Christoffersen, Ryan G. Knox, Max Moritz, Rosie A. Fisher Jul 2021

Assessing Climate Change Impacts On Live Fuel Moisture And Wildfire Risk Using A Hydrodynamic Vegetation Model, Wu Ma, Lu Zhai, Alexandria Pivovaroff, Jacquelyn Shuman, Polly Buotte, Junyan Ding, Bradley O. Christoffersen, Ryan G. Knox, Max Moritz, Rosie A. Fisher

Biology Faculty Publications and Presentations

Live fuel moisture content (LFMC) plays a critical role in wildfire dynamics, but little is known about responses of LFMC to multivariate climate change, e.g., warming temperature, CO2 fertilization, and altered precipitation patterns, leading to a limited prediction ability of future wildfire risks. Here, we use a hydrodynamic demographic vegetation model to estimate LFMC dynamics of chaparral shrubs, a dominant vegetation type in fire-prone southern California. We parameterize the model based on observed shrub allometry and hydraulic traits and evaluate the model's accuracy through comparisons between observed and simulated LFMC of three plant functional types (PFTs) under current climate conditions. …

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Tunable Non-Hermitian Acoustic Filter, S. Puri, J. Ferdous, A. Shakeri, A. Basiri, M. Dubois, Hamidreza Ramezani Jul 2021

Tunable Non-Hermitian Acoustic Filter, S. Puri, J. Ferdous, A. Shakeri, A. Basiri, M. Dubois, Hamidreza Ramezani

Physics and Astronomy Faculty Publications and Presentations

We propose, design, and experimentally test a non-Hermitian acoustic superlattice that acts as a tunable precise filter. The superlattice is composed of two concatenated sublattices. The first sublattice is Hermitian, while the other can be adjusted to be Hermitian or non-Hermitian. The existence of non-Hermiticity, in terms of an induced loss in the second sublattice, results in the generation of absorption resonances that appear in the reflected spectrum. This provides us with a powerful knob to absorb or reflect several frequencies at will with high accuracy. The number of filtered frequencies can be controlled by designing the resonances in the …

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Reshaping The Landscape Of The Future: Software-Defined Manufacturing, Lei Xu, Lin Chen, Zhimin Gao, Hiram Moya, Weidong Shi Jul 2021

Reshaping The Landscape Of The Future: Software-Defined Manufacturing, Lei Xu, Lin Chen, Zhimin Gao, Hiram Moya, Weidong Shi

Computer Science Faculty Publications and Presentations

We describe the concept of software-defined manufacturing, which divides the manufacturing ecosystem into software definition and physical manufacturing layers. Software-defined manufacturing allows better resource sharing and collaboration, and it has the potential to transform the existing manufacturing sector.

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The Conservation Status Of The World’S Freshwater Molluscs, M. Böhm, N. I. Dewhurst-Richman, M. Seddon, C. Albrecht, D. Allen, A. E. Bogan, K. Cummings, G. Darrigran, W. Darwall, Kathryn E. Perez Jul 2021

The Conservation Status Of The World’S Freshwater Molluscs, M. Böhm, N. I. Dewhurst-Richman, M. Seddon, C. Albrecht, D. Allen, A. E. Bogan, K. Cummings, G. Darrigran, W. Darwall, Kathryn E. Perez

Biology Faculty Publications and Presentations

With the biodiversity crisis continuing unchecked, we need to establish levels and drivers of extinction risk, and reassessments over time, to effectively allocate conservation resources and track progress towards global conservation targets. Given that threat appears particularly high in freshwaters, we assessed the extinction risk of 1428 randomly selected freshwater molluscs using the IUCN Red List Categories and Criteria, as part of the Sampled Red List Index project. We show that close to one-third of species in our sample are estimated to be threatened with extinction, with highest levels of threat in the Nearctic, Palearctic and Australasia and among gastropods. …

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Machine Learning Using Host/Guest Energy Histograms To Predict Adsorption In Metal–Organic Frameworks: Application To Short Alkanes And Xe/Kr Mixtures, Zhao Li, Benjamin J. Bucior, Haoyuan Chen, Maciej Haranczyk, J. Ilja Siepmann, Randall Q. Snurr Jul 2021

Machine Learning Using Host/Guest Energy Histograms To Predict Adsorption In Metal–Organic Frameworks: Application To Short Alkanes And Xe/Kr Mixtures, Zhao Li, Benjamin J. Bucior, Haoyuan Chen, Maciej Haranczyk, J. Ilja Siepmann, Randall Q. Snurr

Chemistry Faculty Publications and Presentations

A machine learning (ML) methodology that uses a histogram of interaction energies has been applied to predict gas adsorption in metal–organic frameworks (MOFs) using results from atomistic grand canonical Monte Carlo (GCMC) simulations as training and test data. In this work, the method is first extended to binary mixtures of spherical species, in particular, Xe and Kr. In addition, it is shown that single-component adsorption of ethane and propane can be predicted in good agreement with GCMC simulation using a histogram of the adsorption energies felt by a methyl probe in conjunction with the random forest ML method. The results …

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Disorder Driven Asymmetry And Singular Red Emission In Doped Lu2hf2o7 Nanocrystals With No Charge Compensating Defects, Santosh K. Gupta, Mitzy A. Penilla Garcia, Jose P. Zuniga, Bhupendra B. Srivastava, Yuanbing Mao Jul 2021

Disorder Driven Asymmetry And Singular Red Emission In Doped Lu2hf2o7 Nanocrystals With No Charge Compensating Defects, Santosh K. Gupta, Mitzy A. Penilla Garcia, Jose P. Zuniga, Bhupendra B. Srivastava, Yuanbing Mao

Chemistry Faculty Publications and Presentations

High performance luminescent materials possess low symmetry, high color purity, no charge compensating defects, and high quantum yield. In this work, we have synthesized Lu2Hf2O7 (LuHO) and Lu2Hf2O7:Eu3+ (LuHOE) nanocrystals (NCs) using a molten salt synthesis and confirmed that both are stabilized in defect fluorite structure with a high degree of structural disordering. The LuHO NCs depicted green emission under ultraviolet irradiation, which decreases and increases after being treated in oxidizing and reducing environments, respectively, confirming the role of oxygen vacancies in the emission process. The LuHOE NCs (i) show excitation wavelength-dependent host to dopant energy transfer efficiency, …

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Effects Of Scarification, Phytohormones, Soil Type, And Warming On The Germination And/Or Seedling Performance Of Three Tamaulipan Thornscrub Forest Species, Paula Luera, Kimberly Wahl-Villarreal, Bradley O. Christoffersen, Abeny Treviño, Pushpa Soti, Christopher A. Gabler Jul 2021

Effects Of Scarification, Phytohormones, Soil Type, And Warming On The Germination And/Or Seedling Performance Of Three Tamaulipan Thornscrub Forest Species, Paula Luera, Kimberly Wahl-Villarreal, Bradley O. Christoffersen, Abeny Treviño, Pushpa Soti, Christopher A. Gabler

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

The Tamaulipan thornforests of south Texas and northeast Mexico are an ecologically and economically important conservation hotspot. Thornforest restoration is limited by native tree and shrub seedling availability for planting. Seedling shortages arise from low seed availability and knowledge gaps regarding best practices for germinating and growing the 70+ thornforest species desired for restoration plantings. To fill key knowledge gaps, we investigated three ecologically important thornforest species with low or highly variable germination or seedling survival rates: Ebenopsis ebano, Cordia boissieri, and Zanthoxylum fagara. For each, we quantified the effects of different dosages of chemical seed treatments used to promote …

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Observation Of Gravitational Waves From Two Neutron Star–Black Hole Coalescences, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang Jul 2021

Observation Of Gravitational Waves From Two Neutron Star–Black Hole Coalescences, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We report the observation of gravitational waves from two compact binary coalescences in LIGO's and Virgo's third observing run with properties consistent with neutron star–black hole (NSBH) binaries. The two events are named GW200105_162426 and GW200115_042309, abbreviated as GW200105 and GW200115; the first was observed by LIGO Livingston and Virgo and the second by all three LIGO–Virgo detectors. The source of GW200105 has component masses and , whereas the source of GW200115 has component masses and (all measurements quoted at the 90% credible level). The probability that the secondary's mass is below the maximal mass of a neutron star is …

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Stability Of Peakons And Periodic Peakons For A Nonlinear Quartic Camassa-Holm Equation, Aiyong Chen, Tongjie Deng, Zhijun Qiao Jul 2021

Stability Of Peakons And Periodic Peakons For A Nonlinear Quartic Camassa-Holm Equation, Aiyong Chen, Tongjie Deng, Zhijun Qiao

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In this paper, we study the orbital stability of peakons and periodic peakons for a nonlinear quartic Camassa-Holm equation (QCHE).We first verify that the QCHE has global peakon and periodic peakon solutions. Then by the invariants of the equation and controlling the extrema of the solution, we prove that the shapes of the peakons and periodic peakons are stable under small perturbations in the energy space.

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Latinx Students’ Mathematics Anxiety And Their Study Habits: Exploring Their Relationship At The Postsecondary Level, Luis M. Fernandez, Xiaohui Wang, Olga Ramirez, M. Cristina Villalobos Jul 2021

Latinx Students’ Mathematics Anxiety And Their Study Habits: Exploring Their Relationship At The Postsecondary Level, Luis M. Fernandez, Xiaohui Wang, Olga Ramirez, M. Cristina Villalobos

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Increasing Latinx students’ success in college-level mathematics calls for exploration on their mathematics anxiety as it relates to study habits. Using a sample of Latinx students in a Hispanic Serving Institution and their levels of mathematics anxiety, pairwise analyses revealed significant differences among subgroups. Moreover, regression analyses showed Latinx students’ study habits being predictive of mathematics anxiety. As a result, recommendations are provided that could alleviate mathematics anxiety and its effects on Latinx college students.

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Deep-Sea Biodiversity At The Extremes Of The Salas Y Gómez And Nazca Ridges With Implications For Conservation, Alan M. Friedlander, Whitney Goodell, Jonatha Giddens, Erin E. Easton, Daniel Wagner Jun 2021

Deep-Sea Biodiversity At The Extremes Of The Salas Y Gómez And Nazca Ridges With Implications For Conservation, Alan M. Friedlander, Whitney Goodell, Jonatha Giddens, Erin E. Easton, Daniel Wagner

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

The Salas y Gómez and Nazca ridges are underwater mountain chains that stretch across 2,900 km in the southeastern Pacific and are recognized for their high biodiversity value and unique ecological characteristics. Explorations of deep-water ecosystems have been limited in this region, and elsewhere globally. To characterize community composition of mesophotic and deep-sea demersal fauna at seamounts in the region, we conducted expeditions to Rapa Nui (RN) and Salas y Gómez (SyG) islands in 2011 and Desventuradas Islands in 2013. Remote autonomous baited-cameras were used to conduct stationary video surveys between 150–1,850 m at RN/SyG (N = 20) and 75–2,363 …

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Constraints On Cosmic Strings Using Data From The Third Advanced Ligo–Virgo Observing Run, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang Jun 2021

Constraints On Cosmic Strings Using Data From The Third Advanced Ligo–Virgo Observing Run, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop …

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Tests Of General Relativity With Binary Black Holes From The Second Ligo-Virgo Gravitational-Wave Transient Catalog, R. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, W. H. Wang Jun 2021

Tests Of General Relativity With Binary Black Holes From The Second Ligo-Virgo Gravitational-Wave Transient Catalog, R. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

Gravitational waves enable tests of general relativity in the highly dynamical and strong-field regime. Using events detected by LIGO-Virgo up to 1 October 2019, we evaluate the consistency of the data with predictions from the theory. We first establish that residuals from the best-fit waveform are consistent with detector noise, and that the low- and high-frequency parts of the signals are in agreement. We then consider parametrized modifications to the waveform by varying post-Newtonian and phenomenological coefficients, improving past constraints by factors of ∼2; we also find consistency with Kerr black holes when we specifically target signatures of the spin-induced …

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Miscanthus Biomass For Alternative Energy Production, Jikai Zhao, Donghai Wang, Valentina Pidlisnyuk, Larry E. Erickson Jun 2021

Miscanthus Biomass For Alternative Energy Production, Jikai Zhao, Donghai Wang, Valentina Pidlisnyuk, Larry E. Erickson

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

Biomass such as Miscanthus that is produced using phytoremediation can be used as a biofuel. In some locations it is used for heating homes that are located close to where it is produced. This chapter considers alternative energy technologies for Miscanthus and other plants, including liquid fuels such as ethanol, methane from anaerobic digestion, and pyrolysis (thermal Processing). Pretreatment alternatives to convert cellulose to glucose are reviewed because the economics of ethanol production from Miscanthus are impacted by the efficiency of cellulose hydrolysis to glucose. Size reduc tion of Miscanthus is often the first step in the process because enzymes …

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Quark Matter Contribution To The Heat Capacity Of Magnetized Neutron Stars, Efrain J. Ferrer, Vivian De La Incera, P. Sanson Jun 2021

Quark Matter Contribution To The Heat Capacity Of Magnetized Neutron Stars, Efrain J. Ferrer, Vivian De La Incera, P. Sanson

Physics and Astronomy Faculty Publications and Presentations

In this paper, we find the heat capacity of the magnetic dual chiral density wave (MDCDW) phase of dense quark matter and use it to explore the feasibility of this phase for a neutron star interior. MDCDW is a spatially inhomogeneous phase of quark matter known to be favored at intermediate densities over the chirally symmetric phase and the color-flavor-locked superconducting phase. By comparing our result to the lower limit of the core heat capacity established from observations of transiently accreting neutron stars, we show that the heat capacity of MDCDW quark matter is well above that lower limit and …

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Gwtc-2: Compact Binary Coalescences Observed By Ligo And Virgo During The First Half Of The Third Observing Run, R. Abbott, T. D. Abbott, S. Abraham, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, W. H. Wang Jun 2021

Gwtc-2: Compact Binary Coalescences Observed By Ligo And Virgo During The First Half Of The Third Observing Run, R. Abbott, T. D. Abbott, S. Abraham, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Malik Rakhmanov, Karla E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We report on gravitational-wave discoveries from compact binary coalescences detected by Advanced LIGO and Advanced Virgo in the first half of the third observing run (O3a) between 1 April 2019 15∶00 UTC and 1 October 2019 15∶00 UTC. By imposing a false-alarm-rate threshold of two per year in each of the four search pipelines that constitute our search, we present 39 candidate gravitational-wave events. At this threshold, we expect a contamination fraction of less than 10%. Of these, 26 candidate events were reported previously in near-real time through gamma-ray coordinates network notices and circulars; 13 are reported here for the …

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Dna-Topology Simplification By Topoisomerases, Andreas Hanke, Riccardo Ziraldo, Stephen D. Levene Jun 2021

Dna-Topology Simplification By Topoisomerases, Andreas Hanke, Riccardo Ziraldo, Stephen D. Levene

Physics and Astronomy Faculty Publications and Presentations

The topological properties of DNA molecules, supercoiling, knotting, and catenation, are intimately connected with essential biological processes, such as gene expression, replication, recombination, and chromosome segregation. Non-trivial DNA topologies present challenges to the molecular machines that process and maintain genomic information, for example, by creating unwanted DNA entanglements. At the same time, topological distortion can facilitate DNA-sequence recognition through localized duplex unwinding and longer-range loop-mediated interactions between the DNA sequences. Topoisomerases are a special class of essential enzymes that homeostatically manage DNA topology through the passage of DNA strands. The activities of these enzymes are generally investigated using circular DNA …

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Domes Over Curves, Alexey Glazyrin, Igor Pak Jun 2021

Domes Over Curves, Alexey Glazyrin, Igor Pak

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

A closed piecewise linear curve is called integral if it is comprised of unit intervals. Kenyon's problem asks whether for every integral curve γ in ℝ3, there is a dome over γ, i.e. whether γ is a boundary of a polyhedral surface whose faces are equilateral triangles with unit edge lengths. First, we give an algebraic necessary condition when γ is a quadrilateral, thus giving a negative solution to Kenyon's problem in full generality. We then prove that domes exist over a dense set of integral curves. Finally, we give an explicit construction of domes over all regular n-gons.

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Diving Below The Spin-Down Limit: Constraints On Gravitational Waves From The Energetic Young Pulsar Psr J0537-6910, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang Jun 2021

Diving Below The Spin-Down Limit: Constraints On Gravitational Waves From The Energetic Young Pulsar Psr J0537-6910, R. Abbott, T. D. Abbott, S. Abraham, F. Acernese, Teviet Creighton, Mario C. Diaz, Soma Mukherjee, Volker Quetschke, Karla E. Ramirez, W. H. Wang

Physics and Astronomy Faculty Publications and Presentations

We present a search for quasi-monochromatic gravitational-wave signals from the young, energetic X-ray pulsar PSR J0537-6910 using data from the second and third observing runs of LIGO and Virgo. The search is enabled by a contemporaneous timing ephemeris obtained using Neutron star Interior Composition Explorer (NICER) data. The NICER ephemeris has also been extended through 2020 October and includes three new glitches. PSR J0537-6910 has the largest spin-down luminosity of any pulsar and exhibits fRequent and strong glitches. Analyses of its long-term and interglitch braking indices provide intriguing evidence that its spin-down energy budget may include gravitational-wave emission from a …

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Approaching The Motional Ground State Of A 10-Kg Object, Chris Whittle, E. D. Hall, S. E. Dwyer, N. Mavalvala, Vivishek Sudhir, R. Abbott, A. Ananyeva, C. Austin, L. Barsotti, Karla E. Ramirez Jun 2021

Approaching The Motional Ground State Of A 10-Kg Object, Chris Whittle, E. D. Hall, S. E. Dwyer, N. Mavalvala, Vivishek Sudhir, R. Abbott, A. Ananyeva, C. Austin, L. Barsotti, Karla E. Ramirez

Physics and Astronomy Faculty Publications and Presentations

The motion of a mechanical object— even a human-sized object— should be governed by the rules of quantum mechanics. Coaxing them into a quantum state is, however, difficult: the thermal environment effectively masks any quantum signature of the object’s motion. Indeed, it also masks effects of proposed modifications of quantum mechanics at large mass scales. We prepare the center-of-mass motion of a 10 kg mechanical oscillator in a state with an average phonon occupation of 10.8. The reduction in oscillator temperature, from room temperature to 77 nK, represents a 100-fold improvement in the reduction of temperature of a solid-state mechanical …

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Quantization Coefficients For Uniform Distributions On The Boundaries Of Regular Polygons, Joel Hansen, Itzamar Marquez, Mrinal Kanti Roychowdhury, Eduardo Torres Jun 2021

Quantization Coefficients For Uniform Distributions On The Boundaries Of Regular Polygons, Joel Hansen, Itzamar Marquez, Mrinal Kanti Roychowdhury, Eduardo Torres

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In this paper, we give a general formula to determine the quantization coefficients for uniform distributions defined on the boundaries of different regular m-sided polygons inscribed in a circle. The result shows that the quantization coefficient for the uniform distribution on the boundary of a regular m-sided polygon inscribed in a circle is an increasing function of m, and approaches to the quantization coefficient for the uniform distribution on the circle as m tends to infinity.

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Hexagon Tilings Of The Plane That Are Not Edge-To-Edge, Dirk Frettlöh, Alexey Glazyrin, Z. Lángi Jun 2021

Hexagon Tilings Of The Plane That Are Not Edge-To-Edge, Dirk Frettlöh, Alexey Glazyrin, Z. Lángi

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

An irregular vertex in a tiling by polygons is a vertex of one tile and belongs to the interior of an edge of another tile. In this paper we show that for any integer k≥3, there exists a normal tiling of the Euclidean plane by convex hexagons of unit area with exactly k irregular vertices. Using the same approach we show that there are normal edge-to-edge tilings of the plane by hexagons of unit area and exactly k many n-gons (n>6) of unit area. A result of Akopyan yields an upper bound for k depending on the maximal diameter …

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Energy On Spheres And Discreteness Of Minimizing Measures, Dmitriy Bilyk, Alexey Glazyrin, Ryan Matzke, Josiah Park, Oleksandr Vlasiuk Jun 2021

Energy On Spheres And Discreteness Of Minimizing Measures, Dmitriy Bilyk, Alexey Glazyrin, Ryan Matzke, Josiah Park, Oleksandr Vlasiuk

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

In the present paper we study the minimization of energy integrals on the sphere with a focus on an interesting clustering phenomenon: for certain types of potentials, optimal measures are discrete or are supported on small sets. In particular, we prove that the support of any minimizer of the p-frame energy has empty interior whenever p is not an even integer. A similar effect is also demonstrated for energies with analytic potentials which are not positive definite. In addition, we establish the existence of discrete minimizers for a large class of energies, which includes energies with polynomial potentials.

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Fabrication Of Nd3+ And Yb3+ Doped Nir Emitting Nano Fluorescent Probe: A Candidate For Bioimaging Applications, D. Karthickraja, G. A. Kumar, D. K. Sardar, S. Karthi, Gamage C. Dannangoda, Karen S. Martirosyan, M. Prasath, M. Gowri, E. L. Girija Jun 2021

Fabrication Of Nd3+ And Yb3+ Doped Nir Emitting Nano Fluorescent Probe: A Candidate For Bioimaging Applications, D. Karthickraja, G. A. Kumar, D. K. Sardar, S. Karthi, Gamage C. Dannangoda, Karen S. Martirosyan, M. Prasath, M. Gowri, E. L. Girija

Physics and Astronomy Faculty Publications and Presentations

The intentional design of rare earth doped luminescent architecture exhibits unique optical properties and it can be considered as a promising and potential probe for optical imaging applications. Calcium fluoride (CaF2) nanoparticles doped with optimum concentration of Nd3+ and Yb3+ as sensitizer and activator, respectively, were synthesized by wet precipitation method and characterized by x-ray diffraction (XRD) and photoluminescence. In spite of the fact that the energy transfer takes place from Nd3+ to Yb3+, the luminescence intensity was found to be weak due to the lattice defects generated from the doping of trivalent cations (Nd3+ and Yb3+) for divalent host …

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