Computational criteria for establishing reflex from plasticity to hardwiring (open access)

Computational criteria for establishing reflex from plasticity to hardwiring

Article accompanying a poster for the 2010 Computational Neuroscience Annual Meeting. This article discusses computational criteria for establishing reflex from plasticity to hardwiring.
Date: July 20, 2010
Creator: Tam, Nicoladie D.
System: The UNT Digital Library
A Search for the Decay Modes B +/- to h +/- tau l (open access)

A Search for the Decay Modes B +/- to h +/- tau l

We present a search for the lepton flavor violating decay modes B{sup {+-}} {yields} h{sup {+-}} {tau}{ell} (h = K, {pi}; {ell} = e, {mu}) using the BABAR data sample, which corresponds to 472 million B{bar B} pairs. The search uses events where one B meson is fully reconstructed in one of several hadronic final states. Using the momenta of the reconstructed B, h, and {ell} candidates, we are able to fully determine the {tau} four-momentum. The resulting {tau} candidate mass is our main discriminant against combinatorial background. We see no evidence for B{sup {+-}} {yields} h{sup {+-}} {tau}{ell} decays and set a 90% confidence level upper limit on each branching fraction at the level of a few times 10{sup -5}.
Date: July 20, 2012
Creator: Lees, J.P.
System: The UNT Digital Library
EFFECT OF COMPRESSION ON CONDUCTIVITY AND MORPHOLOGY OF PFSA MEMBRANES (open access)

EFFECT OF COMPRESSION ON CONDUCTIVITY AND MORPHOLOGY OF PFSA MEMBRANES

Polymer-Electrolyte-Fuel-Cells (PEFCs) are promising candidates for powering vehicles and portable devices using renewable-energy sources. The core of a PEFC is the solid electrolyte membrane that conducts protons from anode to cathode, where water is generated. The conductivity of the membrane, however, depends on the water content of the membrane, which is strongly related to the cell operating conditions. The membrane and other cell components are typically compressed to minimize various contact resistances. Moreover, the swelling of a somewhat constrained membrane in the cell due to the humidity changes generates additional compressive stresses in the membrane. These external stresses are balanced by the internal swelling pressure of the membrane and change the swelling equilibrium. It was shown using a fuel-cell setup that compression could reduce the water content of the membrane or alter the cell resistance. Nevertheless, the effect of compression on the membrane’s transport properties is yet to be understood, as well as its implications in the structure-functions relationships of the membrane. We previously studied, both experimentally and theoretically, how compression affects the water content of the membrane.6 However, more information is required the gain a fundamental understanding of the compression effects. In this talk, we present the results of …
Date: July 20, 2011
Creator: Kusoglu, Ahmet; Weber, Adam; Jiang, Ruichin & Gittleman, Craig
System: The UNT Digital Library
A simple method for enzymatic synthesis of unlabeled and radiolabeled Hydroxycinnamate-CoA (open access)

A simple method for enzymatic synthesis of unlabeled and radiolabeled Hydroxycinnamate-CoA

Hydroxycinnamate coenzyme A (CoA) thioesters are substrates for biosynthesis of lignin and hydroxycinna- mate esters of polysaccharides and other polymers. Hence, a supply of these substrates is essential for investigation of cell wall biosynthesis. In this study, three recombinant enzymes, caffeic acid 3-O-methyltransferase, 4-coumarate- CoA ligase 1, and 4-coumarate-CoA ligase 5, were cloned from wheat, tobacco, and Arabidopsis, respectively, and were used to synthesize {sup 14}C-feruloyl-CoA, caffeoyl-CoA, p-coumaroyl-CoA, feruloyl-CoA, and sinapoyl-CoA. The corresponding hydroxycinnamoyl-CoA thioesters were high-performance liquid chromatography purified, the only extraction/purification step necessary, with total yields between 88-95%. Radiolabeled {sup 14}C-feruloyl-CoA was generated from caffeic acid and S-adenosyl-{sup 14}C-methionine under the combined action of caffeic acid 3-O-methyltransferase and 4-coumarate-CoA ligase 1. About 70% of {sup 14}C-methyl groups from S-adenosyl methionine were incorporated into the final product. The methods presented are simple, fast, and efficient for the preparation of the hydroxycinnamate thioesters.
Date: July 20, 2011
Creator: Rautergarten, Carsten; Baidoo, Edward; Keasling, Jay & Vibe Scheller, Henrik
System: The UNT Digital Library
2012 ATOMIC AND MOLECULAR INTERACTIONS GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR, JULY 15-20, 2012 (open access)

2012 ATOMIC AND MOLECULAR INTERACTIONS GORDON RESEARCH CONFERENCE AND GORDON RESEARCH SEMINAR, JULY 15-20, 2012

At the 2012 Atomic and Molecular Interactions Gordon Conference, there will be talks in several broadly defined and partially overlapping areas:  Intramolecular and single-collision reaction dynamics;  Photophysics and photochemistry of excited states;  Clusters, aerosols and solvation;  Interactions at interfaces;  Conformations and folding of large molecules;  Interactions under extreme conditions of temperature and pressure. The theme of the Gordon Research Seminar on Atomic & Molecular Interactions, in keeping with the tradition of the Atomic and Molecular Interactions Gordon Research Conference, is far-reaching and involves fundamental research in the gas and condensed phases along with application of these ideas to practical chemical fields. The oral presentations, which will contain a combination of both experiment and theory, will focus on four broad categories:  Ultrafast Phenomena;  Excited States, Photoelectrons, and Photoions;  Chemical Reaction Dynamics;  Biomolecules and Clusters.
Date: July 20, 2012
Creator: Zwier, Timothy
System: The UNT Digital Library
Ionic liquid pretreatment (open access)

Ionic liquid pretreatment

None
Date: July 20, 2011
Creator: Simmons, Blake; Singh, Seema; Holmes, Bradley & Blanch, Harvey
System: The UNT Digital Library
Comparison of H-Mode Plasmas Diverted to Solid and Liquid Lithium Surfaces (open access)

Comparison of H-Mode Plasmas Diverted to Solid and Liquid Lithium Surfaces

Experiments were conducted with a Liquid Lithium Divertor (LLD) in NSTX. Among the goals was to use lithium recoating to sustain deuterium (D) retention by a static liquid lithium surface, approximating the ability of flowing liquid lithium to maintain chemical reactivity. Lithium evaporators were used to deposit lithium on the LLD surface. Improvements in plasma edge conditions were similar to those with lithiated graphite plasma-facing components (PFCs), including an increase in confinement over discharges without lithiumcoated PFCs and ELM reduction during H-modes. With the outer strike point on the LLD, the D retention in the LLD was about the same as that for solid lithium coatings on graphite, or about two times that achieved without lithium PFC coatings. There were also indications of contamination of the LLD surface, possibly due erosion and redeposition of carbon from PFCs. Flowing lithium may thus be needed for chemically active PFCs during long-pulse operation.
Date: July 20, 2012
Creator: R. Kaita, et. al.
System: The UNT Digital Library
2012 PLANT MOLECULAR BIOLOGY GORDON RESEARCH CONFERENCE, JULY 15-20, 2012 (open access)

2012 PLANT MOLECULAR BIOLOGY GORDON RESEARCH CONFERENCE, JULY 15-20, 2012

The 2012 Gordon Conference on Plant Molecular Biology will present cutting-edge research on molecular aspects of plant growth and development, with particular emphasis on recent discoveries in molecular mechanisms involved with plant signaling systems. The Conference will feature a wide range of topics in plant molecular biology including hormone receptors and early events in hormone signaling, plant perception of and response to plant pathogen and symbionts, as well as technological and biological aspects of epigenomics particularly as it relates to signaling systems that regulate plant growth and development. Genomic approaches to plant signaling will be emphasized, including genomic profiling technologies for quantifying various biological subsystems, such as the epigenome, transcriptome, phosphorylome, and metabolome. The meeting will include an important session devoted to answering the question, "What are the biological and technological limits of plant breeding/genetics, and how can they be solved"?
Date: July 20, 2013
Creator: Sussman, Michael
System: The UNT Digital Library
Calculation of the Effect of Random Superfluid Density on the Temperature Dependence of the Penetration Depth (open access)

Calculation of the Effect of Random Superfluid Density on the Temperature Dependence of the Penetration Depth

Microscopic variations in composition or structure can lead to nanoscale inhomogeneity in superconducting properties such as the magnetic penetration depth, but measurements of these properties are usually made on longer length scales. We solve a generalized London equation with a non-uniform penetration depth {lambda}(r), obtaining an approximate solution for the disorder-averaged Meissner screening. We find that the effective penetration depth is different from the average penetration depth and is sensitive to the details of the disorder. These results indicate the need for caution when interpreting measurements of the penetration depth and its temperature dependence in systems which may be inhomogeneous.
Date: July 20, 2012
Creator: Lippman, Thomas & Moler, Kathryn A.
System: The UNT Digital Library
Pair-distribution function analysis of the structural valence transition in Cp{sub 2}{sup *}Yb(4,4'-Me{sub 2}-bipy) (open access)

Pair-distribution function analysis of the structural valence transition in Cp{sub 2}{sup *}Yb(4,4'-Me{sub 2}-bipy)

The Cp{sup ∗}{sub 2} Yb(L) class of compounds, where Cp{sup ∗}=pentamethylcyclopentadienyl = C{sub 5}Me{sub 5} and L is either a 1,4-diazabutadiene or bipy = 2,2′-bipyridine related ligand, have provided excellent analogies to the Kondo state on the nanoscale. Cp{sup ∗}{sub 2} Yb(4,4′-Me{sub 2}-bipy) furthers this analogy by demonstrating a valence transition as the sample is cooled below 200 K. Here, pair-distribution function (PDF) analysis of x-ray powder diffraction data demonstrate that the Cp{sup ∗}{sub 2}Yb(4,4′-Me{sub 2}-bipy) molecule is virtually unchanged through the valence transition. However, the molecule’s stacking arrangement is altered through the valence transition.
Date: July 20, 2010
Creator: Booth, C H; Bauer, E D; Bozin, E S; Billinge, S J L & Walter, M D
System: The UNT Digital Library
Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators (open access)

Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators

The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.
Date: July 20, 2011
Creator: Osterhoff, Jens; Sokollik, Thomas; Nakamura, Kei; Bakeman, Michael; Weingartner, R; Gonsalves, Anthony et al.
System: The UNT Digital Library
Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability (open access)

Analysis of Conductor Impedances Accounting for Skin Effect and Nonlinear Permeability

It is often necessary to protect sensitive electrical equipment from pulsed electric and magnetic fields. To accomplish this electromagnetic shielding structures similar to Faraday Cages are often implemented. If the equipment is inside a facility that has been reinforced with rebar, the rebar can be used as part of a lighting protection system. Unfortunately, such shields are not perfect and allow electromagnetic fields to be created inside due to discontinuities in the structure, penetrations, and finite conductivity of the shield. In order to perform an analysis of such a structure it is important to first determine the effect of the finite impedance of the conductors used in the shield. In this paper we will discuss the impedances of different cylindrical conductors in the time domain. For a time varying pulse the currents created in the conductor will have different spectral components, which will affect the current density due to skin effects. Many construction materials use iron and different types of steels that have a nonlinear permeability. The nonlinear material can have an effect on the impedance of the conductor depending on the B-H curve. Although closed form solutions exist for the impedances of cylindrical conductors made of linear materials, computational …
Date: July 20, 2011
Creator: Perkins, M. P.; Ong, M. M.; Brown, C. G. & Speer, R. D.
System: The UNT Digital Library
Autonomous Monitoring of Control Hardware to Predict Off-Normal Conditions Using NIF Automatic Alignment Systems (open access)

Autonomous Monitoring of Control Hardware to Predict Off-Normal Conditions Using NIF Automatic Alignment Systems

The National Ignition Facility (NIF) is a high power laser system capable of supporting high-energy-density experimentation as a user facility for the next 30 years. In order to maximize the facility availability, preventive maintenance enhancements are being introduced into the system. An example of such an enhancement is a camera-based health monitoring system, integrated into the automated alignment system, which provides an opportunity to monitor trends in measurements such as average beam intensity, size of the beam, and pixel saturation. The monitoring system will generate alerts based on observed trends in measurements to allow scheduled pro-active maintenance before routine off-normal detection stops system operations requiring unscheduled intervention.
Date: July 20, 2011
Creator: Awwal, A.; Wilhelmsen, K.; Leach, R.; Kamm, V. M.; Burkhart, S.; Lowe-Webb, R. et al.
System: The UNT Digital Library
THE EFFECTS OF HALIDE MODIFIERS ON THE SORPTION KINETICS OF THE LI-MG-N-H SYSTEM (open access)

THE EFFECTS OF HALIDE MODIFIERS ON THE SORPTION KINETICS OF THE LI-MG-N-H SYSTEM

The effects of different transition metal halides (TiCl{sub 3}, VCl{sub 3}, ScCl{sub 3} and NiCl{sub 2}) on the sorption properties of the 1:1 molar ratio of LiNH{sub 2} to MgH{sub 2} are investigated. The modified mixtures were found to contain LiNH{sub 2}, MgH{sub 2} and LiCl. TGA results showed that the hydrogen desorption temperature was reduced with the modifier addition in this order: TiCl{sub 3} > ScCl{sub 3} > VCl{sub 3} > NiCL{sub 2}. Ammonia release was not significantly reduced resulting in a weight loss greater than the theoretical hydrogen storage capacity of the material. The isothermal sorption kinetics of the modified systems showed little improvement after the first dehydrogenation cycle over the unmodified system but showed drastic improvement in rehydrogenation cycles. X-ray diffraction and Raman spectroscopy identified the cycled material to be composed of LiH, MgH{sub 2}, Mg(NH{sub 2}){sub 2} and Mg{sub 3}N{sub 2}.
Date: July 20, 2011
Creator: Anton, D.; Gray, J.; Price, C. & Lascola, R.
System: The UNT Digital Library
Interfacing Chapel with traditional HPC programming languages (open access)

Interfacing Chapel with traditional HPC programming languages

None
Date: July 20, 2011
Creator: Prantl, A.; Epperly, T.; Imam, S. & Sarkar, V.
System: The UNT Digital Library
Ten-fold spectral resolution boosting using TEDI at the Mt. Palomar NIR Triplespec spectrograph (open access)

Ten-fold spectral resolution boosting using TEDI at the Mt. Palomar NIR Triplespec spectrograph

None
Date: July 20, 2011
Creator: Erskine, D. J.; Edelstein, J.; Muirhead, P.; Muterspaugh, M.; Covey, K.; Mondo, D. et al.
System: The UNT Digital Library
Algorithm for precision sub-sample timing between Gaussian like pulses (open access)

Algorithm for precision sub-sample timing between Gaussian like pulses

None
Date: July 20, 2010
Creator: Lerche, R A; Golick, B P; Holder, J P & Kalantar, D H
System: The UNT Digital Library
Development of the Joints for ITER Central Solenoid (open access)

Development of the Joints for ITER Central Solenoid

None
Date: July 20, 2010
Creator: Martovetsky, N. N.; Kenney, S. J. & Miller, J. R.
System: The UNT Digital Library
Shielding Studies for Superconducting RF Cavities at Fermilab (open access)

Shielding Studies for Superconducting RF Cavities at Fermilab

A semi-empirical method that allows us to predict intensity of generated field emission in superconducting RF cavities is described. Spatial, angular and energy distributions of the generated radiation are calculated with the FISHPACT code. The Monte Carlo code MARS15 is used for modeling the radiation transport in matter. A comparison with dose rate measurements performed in the Fermilab Vertical Test Facility for ILC-type cavities with accelerating gradients up to 35 MV/m is presented as well.
Date: July 20, 2010
Creator: Ginsburg, Camille & Rakhno, Igor
System: The UNT Digital Library
Alcohol Withdrawal and Brain Injuries: Beyond Classical Mechanisms (open access)

Alcohol Withdrawal and Brain Injuries: Beyond Classical Mechanisms

This review attempts to provide integrated information at the levels of oxidative signaling mechanisms by which ethanol withdrawal (EW) provokes brain injuries and 17β-estradiol (E2) protects against it. Unmanaged sudden withdrawal from the excessive consumption of alcohol (ethanol) adversely alters neuronal integrity in vulnerable brain regions such as the cerebellum, hippocampus, or cortex.
Date: July 20, 2010
Creator: Jung, Marianna E. & Metzger, Daniel B.
System: The UNT Digital Library
Bot-teachers in hybrid massive open online courses (MOOCs): A post-humanist experience (open access)

Bot-teachers in hybrid massive open online courses (MOOCs): A post-humanist experience

This article explores networked learning technologies and the development of Massive Online Open Courses (MOOCs). The study examines and explains hybrid MOOCs and focuses on the use of bot-teachers within a post-humanist perspective. The research findings reveal that, while the use of bot-teachers is beneficial in terms of facilitating and increasing discourse/interaction, it is ineffective in providing other components of teaching presence. Yet ultimately, learners' positive behaviors indicate that bot-teachers hold promise as an educational tool.
Date: July 20, 2018
Creator: Bozkurt, Aras; Kilgore, Whitney & Crosslin, Matt
System: The UNT Digital Library