Search Results

NSFDEB-NERC: Collaborative Research: Wildlife corridors: do they work and who benefits?

Description: This study will use large corridors and habitat patches that have been stable for 50-200 years, so that genetic patterns reflect the influence of landscape pattern. Each landscape contains a corridor connecting two natural patches and two types of reference conditions, namely two patches lacking a connection that are about the same size and interpatch distance as the connected patches, and an intact natural area containing two sampling locales with similar size and spacing. The study will use 20 independent landscapes to quantify how corridor traits affect gene flow, and will use non-flying mammals as focal species because they are strongly affected by fragmentation. The research team hypothesizes (1) a strong non-linear decline in success (gene flow) with corridor length, reflecting the skewed distribution of dispersal distances within species; (2) success will drop steeply as corridor width falls below a threshold, with the threshold determined by species traits; and (3) species that are bigger, are habitat specialists, or have greater dispersal abilities (relative to brain size or reproductive rate) will benefit more from corridors. Testing these hypotheses will allow generalization to a wide range of mammal species not included in this project. We will use highly flexible Random Forest models to answer the overarching question: What landscape traits (e.g., corridor width, degree of human disturbance) and species traits (mobility, affinity to particular land cover types) are associated with effective corridors?
Date: 2021-01-15/2023-12-31
Creator: Gregory, Andrew
Partner: UNT College of Arts and Sciences

Concentric cone antihydrogen gravity experiment

Description: This article describes a proposed antihydrogen gravity experiment that could be conducted at the CERN Antiproton Decelerator facility to determine the directionality of the acceleration of antihydrogen in earth’s gravitational field.
Date: October 2, 2019
Creator: Patel, S. S.; Sun, S. R. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Artificially structured boundary plasma trap

Description: This article presents a computer simulation of single-species non-neutral plasma confinement using an artificially structured boundary. The results support the prospect of developing plasma space-charge based confinement, with an unmagnetized plasma of one species of charged particles confined by an electric field produced by an edge-confined plasma of a second species of charged particles.
Date: September 20, 2019
Creator: Hedlof, R. M. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Exploratory User Research for Computational Resource for South Asian Languages

Description: Report for the project, Exploratory User Research for CoRSAL, which was an exploratory ethnographic study to generate a foundational understanding of how different user groups might use a planned language archive for South Asian languages. Their research project was to be used by the CoRSAL team to help plan the design of CoRSAL’s infrastructure, and laid the groundwork for further studies that will take a deeper look at issues surrounding the design and use of the planned language archive.
Date: December 7, 2016
Creator: Al Smadi, Duha; Barnes, Sebastian; Blair, Molly; Chong, Miyoung; Cole-Jett, Robin; Davis, Aaron et al.
Partner: UNT College of Arts and Sciences

Terrestrial herpetofauna of Limnos and Agios Efstratios (Northern Aegean, Greece), including new species records for Malpolon insignitus (Geoffroy Saint-Hilaire, 1827) and Pelobates syriacus Boettger, 1889

Description: This article presents herpetofaunal observations from Limnos and Agios Efstratios, two Asia Minor continental shelf islands in the Aegean Sea. Comprehensive surveys over 88 days in total on Limnos, over a period of nine years, consisted mainly of visual encounter surveys and road cruised observations, revealed the presence of three species of amphibians and twelve species of reptiles, including two new species records for the island (Malpolon insignitus and Pelobates syriacus). The results of these surveys provide a clearer understanding of the extant herpetofauna on Limnos and Agios Efstratios and offer discussion on natural history, possible erroneous historical records and preliminary ecological understanding of the herpetofaunal assemblages residing on these islands.
Date: October 25, 2016
Creator: Strachinis, Ilias & Roussos, Stephanos Antonios
Partner: UNT College of Arts and Sciences

The Internet and College Students' Motivation to Vote

Description: This article investigates the impact of the political information available on-line on college students’ motivation to vote. The results illustrate that not only politicians, but educators should be cognizant of this civic engagement process. Schools and teachers of all levels are one the front lines of the battle to create a more informed, more involved citizenry; higher education has a strong influence on motivation to vote.
Date: March 1, 2004
Creator: White, Amy E. & King, Kimi L.
Partner: UNT College of Arts and Sciences

The Impact of Mental Aerobics Training on Older Adults

Description: This article investigates the impact of mental aerobics on older adults. Findings support the conclusion that MA can be an effective intervention in improving older adults’ affectivity, everyday task self-efficacy, and self-rated health.
Date: May 1, 2015
Creator: Hayslip, Bert; Paggi, Kay & Caballero, Daniela
Partner: UNT College of Arts and Sciences

UV and infrared absorption spectra and 248 nm photolysis of maleic anhydride (C₄H₂O₃)

Description: This article investigates maleic anhydride (C₂H₂(CO)₂O, Furan-2,5-dione) that is emitted into or formed in the atmosphere during bio-mass burning events as well as being a photochemical degradation product of some aromatic volatile organic compounds. The photochemical fate of maleic anhydride, however, is presently not well enough characterized to enable modeling of its impact on the environment and human health. In this study, the room temperature UV and infrared absorption spectra of maleic anhydride were measured and quantified using several complementary calibration methods.
Date: July 2, 2019
Creator: Marshall, Paul; Papadimitriou, Vassileios C.; Papanastasiou, Dimitrios K.; Roberts, James M. & Burkholder, James B. (James Bart), 1954-
Partner: UNT College of Arts and Sciences

Climate Metrics for C1–C4 Hydrofluorocarbons (HFCs)

Description: This article looks at hydrofluorocarbons (HFCs) which are potent greenhouse gases that are potential substitutes for ozone depleting substances. The Kigali amendment lists 17 HFCs that are currently in commercial use to be regulated under the Montreal Protocol. Future commercial applications may explore the use of other HFCs, most of which currently lack an evaluation of their climate metrics. In this work, atmospheric lifetimes, radiative efficiencies (REs), global warming potentials (GWPs), and global temperature change potentials (GTPs) for all saturated HFCs with fewer than 5 carbon atoms are estimated to help guide future usage and policy decisions.
Date: May 11, 2020
Creator: Burkholder, James B. (James Bart), 1954-; Marshall, Paul; Bera, Partha P.; Francisco, Joseph S. & Lee, Timothy J.
Partner: UNT College of Arts and Sciences

Experimental and Kinetic Modeling Study of Acetylene Oxidation at High Pressure

Description: Article describing a detailed chemical kinetic model for oxidation of acetylene at intermediate temperatures and high pressure that was developed and evaluated experimentally.
Date: August 29, 2016
Creator: Lopez, Jorge Gimenez; Rasmussen, Christian Lund; Hashemi, Hamid; Alzueta, María U.; Gao, Yide; Marshall, Paul et al.
Partner: UNT College of Arts and Sciences

Simulation Of An Antihydrogen Gravity Experiment Utilizing Multiple Apertures

Description: The article presents an analytical model and a Monte Carlo simulation of an antihydrogen gravity experiment that would employ multiple apertures. The model was developed with the primary goal of reducing the experimental run time necessary to determine the direction of free fall acceleration for antimatter in the gravitational field of the Earth. The experiment would confine cryogenic antihydrogen plasma for producing antihydrogen (e.g., by three-body recombination).
Date: April 19, 2013
Creator: Hedlof, R. M. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Giant cross-magnetic-field steps due to binary collisions between pair particles

Description: Article explores giant cross-magnetic-field steps which occur as a result of positron-electron collisions. Within a constant magnetic field (e.g., 1 T), a collision between a positron and an electron can result in a correlated drift across the magnetic field for a continuous range of impact parameters. Within this range, drift distances orders of magnitude larger than that associated with like-charge collisions were observed by computer simulation.
Date: March 5, 2015
Creator: Aguirre, F. F. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Accelerator-based fusion with a low temperature target

Description: This article reports a study of a cold target with a high Fermi energy in light of recent research that points to a new phase of hydrogen, which is hypothesized to be related to metallic hydrogen. It has been shown that if the energy transfer between injected ions and target electrons is sufficiently small, net energy gain can be achieved. As such, the target is considered to be composed of nuclei and delocalized electrons.
Date: April 19, 2013
Creator: Phillips, R. E. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Dual levitated coils for antihydrogen production

Description: Article on theoretical and experimental efforts to use dual levitated coils to confine relatively large, cold, dense non-drifting recombining antihydrogen plasmas. The theoretical effort includes the development of a classical trajectory Monte Carlo simulation of confinement. The experimental effort includes levitation of a NdFeB permanent ring magnet, which produces a magnetic field that is qualitatively similar to the field that would be produced by the two coaxial superconducting magnetic coils.
Date: April 19, 2013
Creator: Wofford, Joshua D. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Effect of a finite antiproton mass on antihydrogen synthesis via magnetobound positronium within electron-positron-antiproton plasmas

Description: This article describes a study that was conducted to determine what would happen if a magnetobound positronium system encountered a finite-mass antiproton. The simulation incorporates a strong magnetic field (1 T) similar to that found within Penning traps. The simulation shows that with a finite-mass antiproton, the electron will be ejected from the system, and the positron is captured into a bound state with an antiproton thereby synthesizing antihydrogen.
Date: July 2016
Creator: Thornton, E. A. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Artificially Structured Boundary for a high purity ion trap or ion source

Description: This article proposes a plasma enclosed by an Artificially Structured Boundary (ASB) as an alternative to existing ion source assemblies. In accelerator applications, many ion sources can have a limited lifetime or frequent service intervals due to sputtering and eventual degradation of the ion source assembly. Ions are accelerated towards the exit canal of positive ion sources, whereas, due to the biasing scheme, electrons or negative ions are accelerated towards the back of the ion source assembly.
Date: March 27, 2014
Creator: Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences

Phase space of positron trajectories exiting a charged particle source through a magnetic field point cusp

Description: This article presents a configuration of magnetic fields using properties of cylindrically symmetric permanent magnets as a candidate to produce a high purity charged particle source or trap. Cylindrically symmetric hollow permanent magnets produce magnetic field point cusps on the axis of symmetry. A magnetic field point cusp reflects all particles that lie outside a narrow region of phase space, a region dependent on particle kinetic energies and on the magnetic field intensity.
Date: December 30, 2013
Creator: Kiester, A. S.; Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences

Confinement of antiprotons in the electrostatic space charge of positrons in a model of the ALPHA antihydrogen trap

Description: This article details the equilibrium of a positron plasma in a model of the ALPHA apparatus that is computed using a finite-difference method. The positron plasma in the model extends to axial magnetic mirrors in absence of an octupole field. Formation of a three-dimensional electrostatic potential well is found to occur self-consistently. Well depths under various conditions are evaluated. Also, the equilibrium with an antiproton plasma confined in the potential well is computed.
Date: March 17, 2016
Creator: Lane, Ryan A. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Antihydrogen Synthesis Via Magnetobound States of Protonium Within Proton-Positron-Antiproton Plasmas

Description: Article studies the possibility that antihydrogen can be synthesized via three body recombination involving magnetobound protonium through classical trajectory simulation. It has been previously reported that proton antiproton collisions can result in a correlated drift of the particles perpendicular to a magnetic field. While the two particles are in their correlated drift, they are referred to as a magnetobound protonium system. Possible three body recombination resulting in bound state antihydrogen is studied when a magnetobound protonium system encounters a positron.
Date: July 2016
Creator: Hermosillo, M. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Classical trajectory Monte Carlo code for simulating ion beam focusing or defocusing with magnetic elements modeled as current loops or current lines

Description: Article describes a computational tool that can be used for designing magnetic focusing or defocusing systems. A fully three-dimensional classical trajectory Monte Carlo simulation has been developed.
Date: April 19, 2013
Creator: Lane, Ryan A. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Magnetobound positronium and protonium

Description: This article investigates the formation of magnetobound positronium and protonium via classical trajectory simulations of binary point charge interactions in an external magnetic field. The results of computer simulations of the fully three-dimensional trajectories of classical and non-relativistic point charges with the same mass, equal charge magnitude, and opposite sign are reported. The simulations show the formation of magnetobound positronium and protonium. The results yield formation cross sections, which are compared to analytical expressions. Additionally, the results reveal that magnetobound states drift across magnetic field lines.
Date: August 27, 2014
Creator: Correa, J. R. & Ordonez, Carlos A.
Partner: UNT College of Arts and Sciences

Electrostatic storage ring with focusing provided by the space charge of an electron plasma

Description: Article describes an electronic storage ring that employs the space charge of an electron plasma for focusing. An advantage of the present concept is that slow ions, or even a stationary ion plasma, can be confined. The concept employs an artificially structured boundary, which is defined at present as one that produces a spatially periodic static field such that the spatial period and range of the field are much smaller than the dimensions of a plasma or charged-particle beam that is confined by the field.
Date: April 19, 2013
Creator: Pacheco, J. L.; Ordonez, Carlos A. & Weathers, Duncan L.
Partner: UNT College of Arts and Sciences