Physical Sciences and Mathematics Commons^™

The Complete Classification Of Five-Dimensional Dirichlet–Voronoi Polyhedra Of Translational Lattices, Mathieu Dutour Sikiric, Alexey Garber, Achill Schürmann, Clara Waldmann

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

This paper reports on the full classification of Dirichlet–Voronoi polyhedra and Delaunay subdivisions of five-dimensional translational lattices. A complete list is obtained of 110 244 affine types (L-types) of Delaunay subdivisions and it turns out that they are all combinatorially inequivalent, giving the same number of combinatorial types of Dirichlet–Voronoi polyhedra. Using a refinement of corresponding secondary cones, 181 394 contraction types are obtained. The paper gives details of the computer-assisted enumeration, which was verified by three independent implementations and a topological mass formula check.

Asymptotic And Optimal Liouville Properties For Wolff Type Integral Systems, John Villavert

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

This article examines the properties of positive solutions to fully nonlinear systems of integral equations involving Hardy and Wolff potentials. The first part of the paper establishes an optimal existence result and a Liouville type theorem for the integral systems. Then, the second part examines the decay rates of positive bound states at infinity. In particular, a complete characterization of the asymptotic properties of bounded and decaying solutions is given by showing that such solutions vanish at infinity with two principle rates: the slow decay rates and the fast decay rates. In fact, the two rates can be fully distinguished …

The Effect Of Ignoring Statistical Interactions In Regression Analyses Conducted In Epidemiologic Studies: An Example With Survival Analysis Using Cox Proportional Hazards Regression Model, Kristina Vatcheva, Joseph B. Mccormick, Mohammad H. Rahbar

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Objective: To demonstrate the adverse impact of ignoring statistical interactions in regression models used in epidemiologic studies.

Study design and setting: Based on different scenarios that involved known values for coefficient of the interaction term in Cox regression models we generated 1000 samples of size 600 each. The simulated samples and a real life data set from the Cameron County Hispanic Cohort were used to evaluate the effect of ignoring statistical interactions in these models.

Results: Compared to correctly specified Cox regression models with interaction terms, misspecified models without interaction terms resulted in up to 8.95 fold bias in estimated …

Effect Of Polymer Concentration, Rotational Speed, And Solvent Mixture On Fiber Formation Using Forcespinning, Nancy Obregon, Victor Agubra, Madhab Pokhrel, Howard Campos, David Flores, David De La Garza, Yuanbing Mao, Javier Macossay, Mataz Alcoutlabi

Physics and Astronomy Faculty Publications and Presentations

Polycaprolactone (PCL) fibers were produced using Forcespinning® (FS). The effects of PCL concentration, solvent mixture, and the spinneret rotational speed on fiber formation were evaluated. The concentration of the polymer in the solvents was a critical determinant of the solution viscosity. Lower PCL concentrations resulted in low solution viscosities with a correspondingly low fiber production rate with many beads. Bead-free fibers with high production rate and uniform fiber diameter distribution were obtained from the optimum PCL concentration (i.e., 12.5 wt%) with tetrahydrofuran (THF) as the solvent. The addition of N, N-dimethylformamide (DMF) to the THF solvent promoted the gradual formation …

Improved Analysis Of Gw150914 Using A Fully Spin-Precessing Waveform Model, B. P. Abbott, R. Abbott, T. D. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. B. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, L. Aiello, A. Ain, P. Ajith, B. Allen, A. Allocca, P. A. Altin, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. C. Arceneaux, J. S. Areeda, N. Arnaud, K. G. Arun

Physics and Astronomy Faculty Publications and Presentations

This paper presents updated estimates of source parameters for GW150914, a binary black-hole coalescence event detected by the Laser Interferometer Gravitational-wave Observatory (LIGO) in 2015 [Abbott et al. Phys. Rev. Lett. 116, 061102 (2016).]. Abbott et al. [Phys. Rev. Lett. 116, 241102 (2016).] presented parameter estimation of the source using a 13-dimensional, phenomenological precessing-spin model (precessing IMRPhenom) and an 11-dimensional nonprecessing effective-one body (EOB) model calibrated to numerical-relativity simulations, which forces spin alignment (nonprecessing EOBNR). Here, we present new results that include a 15-dimensional precessingspin waveform model (precessing EOBNR) developed within the EOB formalism. We find good agreement with the …

Mapping Gravitational-Wave Backgrounds Of Arbitrary Polarisation Using Pulsar Timing Arrays, Jonathan Gair, Joseph D. Romano, Stephen R. Taylor

Physics and Astronomy Faculty Publications and Presentations

We extend our previous work on mapping gravitational-wave backgrounds using techniques borrowed from the analysis of cosmic microwave background data to backgrounds which have non-general-relativity (non-GR) polarisations. Our analysis and results are presented in the context of pulsar timing array observations, but the overarching methods are general, and can be easily applied to LIGO or eLISA observations using appropriately modified response functions. Analytic expressions for the pulsar timing response to gravitational waves with non-GR polarisation are given for each mode of a spin-weighted spherical-harmonic decomposition of the background, which permit the signal to be mapped across the sky to any …

Coherent Network Analysis For Continuous Gravitational Wave Signals In A Pulsar Timing Array: Pulsar Phases As Extrinsic Parameters, Yan Wang, Soumya D. Mohanty, F. A. Jenet

Physics and Astronomy Faculty Publications and Presentations

Supermassive black hole binaries are one of the primary targets of gravitational wave (GW) searches using pulsar timing arrays (PTAs). GW signals from such systems are well represented by parameterized models, allowing the standard Generalized Likelihood Ratio Test (GLRT) to be used for their detection and estimation. However, there is a dichotomy in how the GLRT can be implemented for PTAs: there are two possible ways in which one can split the set of signal parameters for semi-analytical and numerical extremization. The straightforward extension of the method used for continuous signals in ground-based GW searches, where the so-called pulsar phase …

Mitigating N2o Emissions From Soil: From Patching Leaks To Transformative Action, C. Decock, Juhwan Lee, M. Necpalova, Engil Isadora Pujol Pereira, D. M. Tendall, Johan Six

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

Further progress in understanding and mitigating N2O emissions from soil lies within transdisciplinary research that reaches across spatial scales and takes an ambitious look into the future.

Computational Analysis Of The Sir Mathematical Model For The Dengue Fever, Joseph Phillip Diaz

Theses and Dissertations

Dengue fever is a disease affecting people in more than 100 countries. Here we consider a host and vector model for the transmission of dengue fever. This SIR model consists of three compartments of susceptible, infective and removed for host (human) and two compartments of susceptible and infective for vector (dengue mosquitos). These five compartments yield five coupled nonlinear ordinary differential equations (ODEs). After non-dimensionalization, we have a system of three nonlinear ODEs. Reproductive number and two equilibrium points are calculated for various cases. Simulation is carried out for susceptible, infective and removed and the results are presented in graphical …

Decomposition And Nitrogen Dynamics Of Turtle Grass (Thalassia Testudinum) In A Subtropical Estuarine System, Monica Delgado

Theses and Dissertations

Seagrass beds are pivotal in the functioning of coastal ecosystems in terms of productivity, organic matter turnover and nutrient cycling. Aiming to document decay and nitrogen (N) dynamics of turtle grass (Thalassia testudinum) in a subtropical estuarine system, decomposition patterns of leaves and rhizomes were characterized and compared. Nitrogen usage during decomposition of tissues, and of live tissues and epiphytes growing on live leaves, was also quantified and compared. Stable isotope ratios allowed tracing N within the seagrass bed, following N incorporation into seagrass tissues from the surrounding media (water, sediment). Leaves had a higher N content and decomposed at …

First Astrophysical Observations With The Low Frequency All Sky Monitor, Emma Youmans Handzo

Theses and Dissertations

The Low Frequency All Sky Monitor (LoFASM) is a radio telescope that consists of dipole antennas. It is sensitive to the frequencies of 10-88MHz. The primary science goals of LoFASM are to detect and study low frequency radio transient events and to develop and test low frequency interference (RFI) mitigation techniques.

Once a telescope starts collecting data, it is necessary to calibrate the telescope to convert the data into standard units. This will allow for scientific deductions to be made from the data. Once the calibration of a telescope is complete it is necessary to determine what astrophysical sources are …

Molecular Modeling And Mutational Mapping Of The Gpr119 Binding Site, Shane M. Askar

Theses and Dissertations

GPR119 receptor’s biological role in regulating glucose homeostasis has been studied extensively. Results in the scientific literature indicate that, when activated, GPR119 releases insulin in a glucose dependent manner. Currently the 3D structure of GPR119 has not been resolved.

The goal of this research is to use a combination of homology modeling and ligand docking studies to predict the binding mode of GPR119 ligands. Amino acids implicated to have direct interactions with docked ligands will further be assessed experimentally for their roll in binding and activation of GPR119. Our results indicate that residues W2656.48 and R813.28 are likely to be …

Facile Sol-Gel Molten Salt Synthesis Of Double Perovskite La 2nimno6 As An Electrocatalyst For Oxygen Evolution Reactions, Padmini Kukkapalli

Theses and Dissertations

Double perovskites have attracted a great attention recently for its high intrinsic activity in oxygen evolution reaction (OER) in electrochemical energy storage and conversion systems in alkaline media. In this study, we are the first to report the new approach of La2NiMnO6 double perovskite which was synthesized via Sol-gel molten-Salt synthesis method. However their stability and specific activity remain challenging that need to be addressed to meet the reqiurement for OER activities. Here in this study we synthesized three different samples with varying concentrations by taking molten salts NaNO 3 and KNO3 in (1:1) ratio such as 30:30, 60:60, 90:90. …

3d Reconstruction Of Close Range Objects Using Free And Open Source Software And Raspberry Pi Technologies, Juan Lorenzo Monrreal

Theses and Dissertations

Existing 3D rendering open source software along with Raspberry Pi technology can be used to create an affordable method and workflow for time efficient, accurate and quality scans for 3D printing. The emergence of technology spurs a technological community working to progress in a collaborative effort. This brings a potential to the possibility of efficient and economical solutions to emerging problems, in this case, the ability to render three dimensional scans using free and open source software as well as Raspberry Pi technology. The focus of this paper will be divided into three different aspects including the background needed to …

The Bourbaki-Jacobson Correspondence, Jose R. Vera

Theses and Dissertations

A general ring theoretic correspondence between subrings of the endomorphism ring of the additive group of a commutative field will be established. This correspondence (called Bourbaki-Jacobson Correspondence) provides the ordinary Galois correspondence when applied to specific group rings. Throughout this thesis, we will work with finite dimensional field extensions.

Use Of Cubic B-Spline In Approximating Solutions Of Boundary Value Problems, Maria Mungia, Dambaru Bhatta

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Here we investigate the use of cubic B-spline functions in solving boundary value problems. First, we derive the linear, quadratic, and cubic B-spline functions. Then we use the cubic B-spline functions to solve second order linear boundary value problems. We consider constant coefficient and variable coefficient cases with non-homogeneous boundary conditions for ordinary differential equations. We also use this numerical method for the space variable to obtain solutions for second order linear partial differential equations. Numerical results for various cases are presented and compared with exact solutions.

On The Disk Wind Mass Loss Rates In Qsos, Nicolas A. Pereyra

Physics and Astronomy Faculty Publications and Presentations

We derive here a relatively simple expression for the total wind mass loss rates in QSOs within the accretion disk wind scenario. We show that the simple expression derived here for QSO disk wind mass loss rate is in a very good agreement with the more “exact” values obtained through significantly more complex and detailed numerically intensive 2.5D time-dependent simulations. Additionally we show that for typical QSO parameters, the disk itself will be emitting mostly in the UV/optical spectrum, in turn implying that the X-ray emission from QSOs likely is produced through some physical mechanism acting at radii smaller than …

Genomic And Transcriptomic Evidence For Scavenging Of Diverse Organic Compounds By Widespread Deep-Sea Archaea, Meng Li, Brett J. Baker, Karthik Anantharaman, Sunit Jain, John A. Breier, Gregory J. Dick

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

Microbial activity is one of the most important processes to mediate the flux of organic carbon from the ocean surface to the seafloor. However, little is known about the microorganisms that underpin this key step of the global carbon cycle in the deep oceans. Here we present genomic and transcriptomic evidence that five ubiquitous archaeal groups actively use proteins, carbohydrates, fatty acids and lipids as sources of carbon and energy at depths ranging from 800 to 4,950 m in hydrothermal vent plumes and pelagic background seawater across three different ocean basins. Genome-enabled metabolic reconstructions and gene expression patterns show that …

Searches For Continuous Gravitational Waves From Nine Young Supernova Remnants, J. Aasi, B. P. Abbott, R. Abbott, T. Abbott, M. R. Abernathy, F. Acernese, K. Ackley, C. Adams, T. Adams, P. Addesso, R. X. Adhikari, V. Adya, C. Affeldt, M. Agathos, K. Agatsuma, N. Aggarwal, O. D. Aguiar, A. Ain, P. Ajith, A. Alemic, B. Allen, A. Allocca, D. Amariutei, S. B. Anderson, W. G. Anderson, K. Arai, M. C. Araya, C. Arceneaux, J. S. Areeda, S. Ast

Physics and Astronomy Faculty Publications and Presentations

We describe directed searches for continuous gravitational waves (GWs) in data from the sixth Laser Interferometer Gravitational-wave Observatory (LIGO) science data run. The targets were nine young supernova remnants not associated with pulsars; eight of the remnants are associated with non-pulsing suspected neutron stars. One target's parameters are uncertain enough to warrant two searches, for a total of 10. Each search covered a broad band of frequencies and first and second frequency derivatives for a fixed sky direction. The searches coherently integrated data from the two LIGO interferometers over time spans from 5.3-25.3 days using the matched-filtering -statistic. We found …

The Nanograv Nine-Year Data Set: Observations Arrival Time Measurements And Analysis Of 37 Millisecond Pulsars, Z. Arzoumanian, Zaven Arzoumanian, Adam Brazier, Sarah Burke-Spolaor, Sydney Chamberlin, Shami Chatterjee, Brian Christy, James M. Cordes, Neil Cornish, Fredrick A. Jenet, Jing Luo

Physics and Astronomy Faculty Publications and Presentations

We present high-precision timing observations spanning up to nine years for 37 millisecond pulsars monitored with the Green Bank and Arecibo radio telescopes as part of the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) project. We describe the observational and instrumental setups used to collect the data, and methodology applied for calculating pulse times of arrival; these include novel methods for measuring instrumental offsets and characterizing low signal-to-noise ratio timing results. The time of arrival data are fit to a physical timing model for each source, including terms that characterize time-variable dispersion measure and frequency-dependent pulse shape evolution. In …

On The Formation And Evolution Of The First Be Star In A Black Hole Binary Mwc 656, M. Grudzinska, K. Belczynski, J. Casares, S. E. De Mink, J. Ziolkowski, I. Negueruela, M. Ribó, I. Ribas, J. M. Paredes, A. Herrero, M. Benacquista

Physics and Astronomy Faculty Publications and Presentations

We find that the formation of MWC 656 (the first Be binary containing a black hole) involves a common envelope phase and a supernova explosion. This result supports the idea that a rapidly rotating Be star can emerge out of a common envelope phase, which is very intriguing because this evolutionary stage is thought to be too fast to lead to significant accretion and spin up of the B star.We predict ~10-100 of B-BH binaries to currently reside in the Galactic disc, among which around 1/3 contain a Be star, but there is only a small chance to observe a …

Pulsar J0453+1559: A Double Neutron Star System With A Large Mass Asymmetry, J. G. Martinez, K. Stovall, P. C.C. Freire, J. S. Deneva, F. A. Jenet, M. A. Mclaughlin, M. Bagchi, S. D. Bates, A. Ridolfi

Physics and Astronomy Faculty Publications and Presentations

To understand the nature of supernovae and neutron star (NS) formation, as well as binary stellar evolution and their interactions, it is important to probe the distribution of NS masses. Until now, all double NS (DNS) systems have been measured as having a mass ratio close to unity (q ≥ 0.91). Here, we report the measurement of the individual masses of the 4.07-day binary pulsar J0453+1559 from measurements of the rate of advance of periastron and Shapiro delay: the mass of the pulsar is Mp = 1.559 � 0.005 Mo and that of its companion is Mo; q = 0.75. …

Arecibo Pulsar Survey Using Alfa. Iv. Mock Spectrometer Data Analysis Survey Sensitivity And The Discovery Of 40 Pulsars, P. Lazarus, A. Brazier, J. W.T. Hessels, C. Karako-Argaman, V. M. Kaspi, R. Lynch, E. Madsen, C. Patel, S. M. Ransom, P. Scholz, J. Swiggum, W. W. Zhu, B. Allen, S. Bogdanov, F. Camilo, F. Cardoso, S. Chatterjee, J. M. Cordes, F. Crawford, J. S. Deneva, R. Ferdman, P. C.C. Freire, F. A. Jenet, B. Knispel, K. J. Lee, J. Van Leeuwen, D. R. Lorimer, A. G. Lyne, M. A. Mclaughlin, X. Siemens

Physics and Astronomy Faculty Publications and Presentations

The on-going Arecibo Pulsar-ALFA (PALFA) survey began in 2004 and is searching for radio pulsars in the Galactic plane at 1.4 GHz. Here we present a comprehensive description of one of its main data reduction pipelines that is based on the PRESTO software and includes new interference-excision algorithms and candidate selection heuristics. This pipeline has been used to discover 40 pulsars, bringing the surveys discovery total to 144 pulsars. Of the new discoveries, eight are millisecond pulsars (MSPs; P 10 ms) and one is a Fast Radio Burst (FRB). This pipeline has also re-detected 188 previously known pulsars, 60 of …

Depression, Obesity, And Metabolic Syndrome: Prevalence And Risks Of Comorbidity In A Population-Based Study Of Mexican Americans, Rene L. Olvera, Douglas E. Williamson, Susan P. Fisher-Hoch, Kristina Vatcheva, Joseph B. Mccormick

School of Mathematical and Statistical Sciences Faculty Publications and Presentations

Introduction: We examined the prevalence of depression, obesity, and metabolic syndrome and associations between them in a population-based representative cohort of Mexican Americans living on the United States-Mexico border.

Method: The sample in this cross-sectional analysis consisted of 1,768 Mexican American adults (≥ 18 years of age) assessed between the years 2004 and 2010, with whom we tested our central hypothesis of a significant relationship between obesity and depression. Depression was measured using the Center for Epidemiologic Studies-Depression scale (CES-D) with a cutoff score of ≥ 16 for depression and a cutoff score of ≥ 27 for severe depression. We …

Using Fish Population Metrics To Compare The Effects Of Artificial Reef Density, Catheline Y. M. Froehlich, Richard Kline

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

Artificial reefs continue to be added as habitat throughout the world, yet questions remain about how reef design affects fish diversity and abundance. In the present study, the effects of reef density were assessed for fish communities and sizes of economically valuable Lutjanus campechanus 13 km off Port Mansfield, Texas, at a reef composed of more than 4000 concrete culverts. The study spanned from May to June in 2013 and 2014, and sites sampled included natural reefs, bare areas, and varying culvert patch density categories, ranging from 1–190 culverts. Abundances of adults and species evenness of juvenile populations differed between …

Depth-Resolved Multispectral Sub-Surface Imaging Using Multifunctional Upconversion Phosphors With Paramagnetic Properties, Zaven Ovanesyan, L. Christopher Mimun, Gangadharan Ajith Kumar, Brian G. Yust, Chamath Dannongoda, Karen S. Martirosyan, Dhiraj K. Sardar

Physics and Astronomy Faculty Publications and Presentations

Molecular imaging is very promising technique used for surgical guidance, which requires advancements related to properties of imaging agents and subsequent data retrieval methods from measured multispectral images. In this article, an upconversion material is introduced for subsurface near-infrared imaging and for the depth recovery of the material embedded below the biological tissue. The results confirm significant correlation between the analytical depth estimate of the material under the tissue and the measured ratio of emitted light from the material at two different wavelengths. Experiments with biological tissue samples demonstrate depth resolved imaging using the rare earth doped multifunctional phosphors. In …

Microwave Spectra And Structure Of The Cyclopropanecarboxylic Acid-Formic Acid Dimer, Aaron M. Pejlovas, Wei Lin, Stephen G. Kukolich

Chemistry Faculty Publications and Presentations

The rotational spectrum of the cyclopropanecarboxylic acid-formic acid doubly hydrogen bonded dimer has been measured in the 4-11 GHz region using a Flygare-Balle type pulsed-beam Fourier transform microwave spectrometer. Rotational transitions were measured for the parent, four unique singly substituted ¹³C isotopologues, and a singly deuterated isotopologue. Splittings due to a possible concerted double proton tunneling motion were not observed. Rotational constants (A, B, and C) and centrifugal distortion constants (DJ and DJK) were determined from the measured transitions for the dimer. The values of the rotational (in MHz) and centrifugal distortion constants (in kHz) for the parent isotopologue …

Nanograv Constraints On Gravitational Wave Bursts With Memory, Z. Arzoumanian, A. Brazier, S. Burke-Spolaor, S. J. Chamberlin, S. Chatterjee, B. Christy, J. M. Cordes, N. J. Cornish, Fredrick A. Jenet, Jing Luo

Physics and Astronomy Faculty Publications and Presentations

Among efforts to detect gravitational radiation, pulsar timing arrays are uniquely poised to detect \"memory\" signatures, permanent perturbations in spacetime from highly energetic astrophysical events such as mergers of supermassive black hole binaries. The North American Nanohertz Observatory for Gravitational Waves (NANOGrav) observes dozens of the most stable millisecond pulsars using the Arecibo and Green Bank radio telescopes in an effort to study, among other things, gravitational wave memory. We herein present the results of a search for gravitational wave bursts with memory (BWMs) using the first five years of NANOGrav observations. We develop original methods for dramatically speeding up …

A Comparative Study Of Polyurethane Nanofibers With Different Patterns And Its Analogous Nanofibers Containing Mwcnts, Javier Macossay-Torres, Faheem A. Sheikh, Hassan Ahmad, Hern Kim, Gary L. Bowlin

Chemistry Faculty Publications and Presentations

Tissue engineering is a multidisciplinary field that has evolved in various dimensions in recent years. One of the main aspects in this field is the proper adjustment and final compatibility of implants at the target site of surgery. For this purpose, it is desired to have the materials fabricated at the nanometer scale, since these dimensions will ultimately accelerate the fixation of implants at the cellular level. In this study, electrospun polyurethane nanofibers and their analogous nanofibers containing MWCNTs are introduced for tissue engineering applications. Since MWCNTs agglomerate to form bundles, a high intensity sonication procedure was used to disperse …

Dna Cyclization And Looping In The Wormlike Limit: Normal Modes And The Validity Of The Harmonic Approximation, Stefan M. Giovan, Andreas Hanke, Stephen D. Levene

Physics and Astronomy Faculty Publications and Presentations

For much of the last three decades, Monte Carlo-simulation methods have been the standard approach for accurately calculating the cyclization probability, J, or J factor, for DNA models having sequence-dependent bends or inhomogeneous bending flexibility. Within the last 10 years approaches based on harmonic analysis of semi-flexible polymer models have been introduced, which offer much greater computational efficiency than Monte Carlo techniques. These methods consider the ensemble of molecular conformations in terms of harmonic fluctuations about a well-defined elastic-energy minimum. However, the harmonic approximation is only applicable for small systems, because the accessible conformation space of larger systems is increasingly …