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Phase Equilibria in High Energy Density PVDF-Based Polymers (open access)

Phase Equilibria in High Energy Density PVDF-Based Polymers

Article on phase equilibria in high energy density PVDF-based polymers.
Date: July 27, 2007
Creator: Ranjan, Vivek; Yu, Liping; Buongiorno Nardelli, Marco & Bernholc, Jerry
System: The UNT Digital Library
Switchgrass (Panicum virgatum) possesses a divergent family of cinnamoyl CoA reductases with distinct biochemical properties (open access)

Switchgrass (Panicum virgatum) possesses a divergent family of cinnamoyl CoA reductases with distinct biochemical properties

Article on switchgrass (Panicum virgatum) possessing a divergent family of cinnamoyl CoA reductases with distinct biochemical properties.
Date: July 27, 2009
Creator: Escamilla-Treviño, Luis; Shen, Hui; Uppalapati, Srinivasa Rao; Ray, Tui; Tang, Yuhong; Hernandez, Timothy et al.
System: The UNT Digital Library
Experimental Quenching of Harmonic Stimuli: Universality of Linear Response Theory (open access)

Experimental Quenching of Harmonic Stimuli: Universality of Linear Response Theory

This article discusses experimental quenching of harmonic stimuli.
Date: July 15, 2009
Creator: Allegrini, Paolo; Bologna, Mauro; Fronzoni, Leone; Grigolini, Paolo & Silvestri, Ludovico
System: The UNT Digital Library
Fluctuation-Dissipation Theorem for Event-Dominated Processes (open access)

Fluctuation-Dissipation Theorem for Event-Dominated Processes

Article discussing the fluctuation-dissipation theorem for event-dominated processes.
Date: July 6, 2007
Creator: Allegrini, Paolo; Bologna, Mauro; Grigolini, Paolo & West, Bruce J.
System: The UNT Digital Library
New experimental capabilities and theoretical insights of high pressure compression waves (open access)

New experimental capabilities and theoretical insights of high pressure compression waves

Currently there are three platforms that offer quasi-isentropic compression or ramp-wave compression (RWC): light-gas gun, magnetic flux (Z-pinch), and laser. We focus here on the light-gas gun technique and on some current theoretical insights from experimental data. A gradient impedance through the length of the impactor provides the pressure pulse upon impactor to the subject material. Applications and results are given concerning high-pressure strength and liquid to solid, phase transition of water plus its associated phase fraction history. We also introduce the Korteweg-deVries-Burgers equation as a means to understand the evolution these RWC waves that propagate through the thickness of the subject material. This equation has the necessary competition between non-linear, dispersion, and dissipation processes, which is shown through observed structures that are manifested in the experimental particle velocity histories. Such methodology points towards a possible quantifiable dissipation, through which RWC experiments may be analyzed.
Date: July 20, 2007
Creator: Orlikowski, D.; Nguyen, J.; Patterson, J. R.; Minich, R.; Martin, L. P. & Holmes, N.
System: The UNT Digital Library
Loss Factor of the PEP-II Rings (open access)

Loss Factor of the PEP-II Rings

An RF power balance method is used to measure the synchrotron radiation losses and the wake field losses. We present the history of the losses in the Low Energy Ring (LER) and the High Energy Ring (HER) during the last several runs of PEP-II.
Date: July 11, 2008
Creator: Novokhatski, A. & Sullivan, M.
System: The UNT Digital Library
Elastic electron scattering from formic acid (open access)

Elastic electron scattering from formic acid

Following our earlier study on the dynamics of low energy electron attachment to formic acid, we report the results of elastic low-energy electron collisions with formic acid. Momentum transfer and angular differential cross sections were obtained by performing fixed-nuclei calculations employing the complex Kohn variational method. We make a brief description of the technique used to account for the polar nature of this polyatomic target and compare our results with available experimental data.
Date: July 31, 2006
Creator: Trevisan, Cynthia S.; Orel, Ann E. & Rescigno, Thomas N.
System: The UNT Digital Library
Certifying Industrial Energy Efficiency Performance: AligningManagement, Measurement, and Practice to Create Market Value (open access)

Certifying Industrial Energy Efficiency Performance: AligningManagement, Measurement, and Practice to Create Market Value

More than fifteen years after the launch of programs in theU.K. and U.S., industry still offers one of the largest opportunities forenergy savings worldwide. The International Energy Agency (IEA) estimatesthe savings potential from cost-optimization of industrial motor-drivensystems alone at 7 percent of global electricity use. The U.S. Departmentof Energy (USDOE) Industrial Technologies Program estimates 7 percentsavings potential in total US industrial energy use through theapplication of proven best practice. Simple paybacks for these types ofprojects are frequently two years or less. The technology required toachieve these savings is widely available; the technical skills requiredto identify energy saving opportunities are known and transferable.Although programs like USDOE's Best Practices have been highlysuccessful, most plants, as supported by 2002 MECS data, remain eitherunaware or unmotivated to improve their energy efficiency--as evidencedby the 98 percent of US industrial facilities reporting to MECS say thatthey lack a full-time energy manager. With the renewed interest in energyefficiency worldwide and the emergence of carbon trading and newfinancial instruments such as white certificates1, there is a need tointroduce greater transparency into the way that industrial facilitiesidentify, develop, and document energy efficiency projects. Historically,industrial energy efficiency projects have been developed by plantengineers, frequently with assistance from consultants and/or supplierswith …
Date: July 1, 2007
Creator: McKane, Aimee; Scheihing, Paul & Williams, Robert
System: The UNT Digital Library
First Principles Study of Double Photoionization of H2 UsingExterior Complex Scaling (open access)

First Principles Study of Double Photoionization of H2 UsingExterior Complex Scaling

Exterior complex scaling provides a practical path forfirst-principles studies of atomic and molecular ionizationproblemssince it avoids explicit enforcement of asymptotic boundary conditionsfor 3-body Coulomb breakup. We have used the method of exterior complexscaling, implemented with both the discrete variable representation andB-splines, to obtain the first-order wave function for molecular hydrogencorresponding to a single photon having been absorbed by a correlatedinitial state. These wave functions are used to construct convergedtriple differential cross sections for double photoionization of alignedH2 molecules.
Date: July 21, 2006
Creator: Rescigno, Thomas N.; Vanroose, Wim; Horner, Daniel A.; Martin,Fernando & McCurdy, C. William
System: The UNT Digital Library
Quench performance of Nb3Sn cos-theta coils made of 108/127 RRP strands (open access)

Quench performance of Nb3Sn cos-theta coils made of 108/127 RRP strands

A series of 1-m long Nb{sub 3}Sn dipole models has been built at Fermilab in an attempt to refine the wind-and-react technology for Nb3Sn accelerator magnets. Three models made with Powder-in-Tube Nb{sub 3}Sn strand reached their design field of 10 T demonstrating a good reproducibility of magnet quench performance and field quality. Recently a new dipole 'mirror' model based on Nb{sub 3}Sn coil made of improved Restack Rod Process strand was constructed and tested reaching the maximum field above 11 T. This paper describes the parameters of the RRP strand and cable used as well as the design, fabrication and test results of this magnet.
Date: July 1, 2007
Creator: Zlobin, A.V.; Ambrosio, G.; Andreev, N.; Barzi, E.; Bossert, R.; Carcagno, R. et al.
System: The UNT Digital Library
Radio-loud high-redshift protogalaxy canidates in Bootes (open access)

Radio-loud high-redshift protogalaxy canidates in Bootes

We used the Near Infrared Camera (NIRC) on Keck I to obtain K{sub s}-band images of four candidate high-redshift radio galaxies selected using optical and radio data in the NOAO Deep Wide-Field Survey in Bootes. Our targets have 1.4 GHz radio flux densities greater than 1 mJy, but are undetected in the optical. Spectral energy distribution fitting suggests that three of these objects are at z > 3, with radio luminosities near the FR-I/FR-II break. The other has photometric redshift z{sub phot} = 1.2, but may in fact be at higher redshift. Two of the four objects exhibit diffuse morphologies in K{sub s}-band, suggesting that they are still in the process of forming.
Date: July 20, 2007
Creator: Croft, S.; van Breugel, W.; Brown, M. J.; de Vries, W.; Dey, A.; Eisenhardt, P. et al.
System: The UNT Digital Library
A fast contour descriptor algorithm for supernova imageclassification (open access)

A fast contour descriptor algorithm for supernova imageclassification

We describe a fast contour descriptor algorithm and its application to a distributed supernova detection system (the Nearby Supernova Factory) that processes 600,000 candidate objects in 80 GB of image data per night. Our shape-detection algorithm reduced the number of false positives generated by the supernova search pipeline by 41% while producing no measurable impact on running time. Fourier descriptors are an established method of numerically describing the shapes of object contours, but transform-based techniques are ordinarily avoided in this type of application due to their computational cost. We devised a fast contour descriptor implementation for supernova candidates that meets the tight processing budget of the application. Using the lowest-order descriptors (F{sub 1} and F{sub -1}) and the total variance in the contour, we obtain one feature representing the eccentricity of the object and another denoting its irregularity. Because the number of Fourier terms to be calculated is fixed and small, the algorithm runs in linear time, rather than the O(n log n) time of an FFT. Constraints on object size allow further optimizations so that the total cost of producing the required contour descriptors is about 4n addition/subtraction operations, where n is the length of the contour.
Date: July 16, 2006
Creator: Aragon, Cecilia R. & Aragon, David Bradburn
System: The UNT Digital Library
Searches for Large Extra Dimensions at the Tevatron (open access)

Searches for Large Extra Dimensions at the Tevatron

None
Date: July 1, 2008
Creator: Krutelyov, Vyacheslav
System: The UNT Digital Library
Mg-induced increase of bandgap in Zn1-xMgxO nanorods revealed by x-ray absorption and emission spectroscopy (open access)

Mg-induced increase of bandgap in Zn1-xMgxO nanorods revealed by x-ray absorption and emission spectroscopy

X-ray absorption near-edge structure (XANES) and x-ray emission spectroscopy (XES) measurements were used to investigate the effect of Mg doping in ZnO nanorods. The intensities of the features in the O K-edge XANES spectra of Zn{sub 1-x}Mg{sub x}O nanorods are lower than those of pure ZnO nanorods, suggesting that Mg doping increases the negative effective charge of O ions. XES and XANES spectra of O 2p states indicate that Mg doping raises (lowers) the conduction-band-minimum (valence-band-maximum) and increases the bandgap. The bandgap is found to increase linearly with the Mg content, as revealed by photoluminescence and combined XANES and XES measurements.
Date: July 10, 2008
Creator: Pong, Way-Faung; Chiou, J. W.; Tsai, H. M.; Pao, C. W.; Chien, F. Z.; Pong, W. F. et al.
System: The UNT Digital Library
Multiple Valley Couplings in Nanometer Si MOSFETs (open access)

Multiple Valley Couplings in Nanometer Si MOSFETs

We investigate the couplings between different energy band valleys in a MOSFET device using self-consistent calculations of million-atom Schroedinger-Poisson Equations. Atomistic empirical pseudopotentials are used to describe the device Hamiltonian and the underlying bulk band structure. The MOSFET device is under nonequilibrium condition with a source-drain bias up to 2V, and a gate potential close to the threshold potential. We find that all the intervalley couplings are small, with the coupling constants less than 3 meV. As a result, the system eigenstates derived from different bulk valleys can be calculated separately. This will significantly reduce the simulation time, because the diagonalization of the Hamiltonian matrix scales as the third power of the total number of basis functions.
Date: July 11, 2008
Creator: Wang, Lin-Wang; Deng, Hui-Xiong; Jiang, Xiang-Wei; Luo, Jun-Wei; Li, Shu-Shen; Xia, Jian-Bai et al.
System: The UNT Digital Library
Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds. (open access)

Fine-scale Horizontal Structure of Arctic Mixed-Phase Clouds.

Recent in situ observations in stratiform clouds suggest that mixed phase regimes, here defined as limited cloud volumes containing both liquid and solid water, are constrained to narrow layers (order 100 m) separating all-liquid and fully glaciated volumes (Hallett and Viddaurre, 2005). The Department of Energy Atmospheric Radiation Measurement Program's (DOE-ARM, Ackerman and Stokes, 2003) North Slope of Alaska (NSA) ARM Climate Research Facility (ACRF) recently started collecting routine measurement of radar Doppler velocity power spectra from the Millimeter Cloud Radar (MMCR). Shupe et al. (2004) showed that Doppler spectra has potential to separate the contributions to the total reflectivity of the liquid and solid water in the radar volume, and thus to investigate further Hallett and Viddaurre's findings. The Mixed-Phase Arctic Cloud Experiment (MPACE) was conducted along the NSA to investigate the properties of Arctic mixed phase clouds (Verlinde et al., 2006). We present surface based remote sensing data from MPACE to discuss the fine-scale structure of the mixed-phase clouds observed during this experiment.
Date: July 10, 2006
Creator: Rambukkange,M.; Verlinde, J.; Elorante, E.; Luke, E.; Kollias, P. & Shupe, M.
System: The UNT Digital Library
Pathway confirmation and flux analysis of central metabolicpathways in Desulfovibrio vulgaris Hildenborough using gaschromatography-mass spectrometry and fourier transform-ion cyclotronresonance mass spectrometry (open access)

Pathway confirmation and flux analysis of central metabolicpathways in Desulfovibrio vulgaris Hildenborough using gaschromatography-mass spectrometry and fourier transform-ion cyclotronresonance mass spectrometry

It has been proposed that during growth under anaerobic oroxygen-limited conditions Shewanella oneidensis MR-1 uses theserine-isocitrate lyase pathway common to many methylotrophic anaerobes,in which formaldehyde produced from pyruvate is condensed with glycine toform serine. The serine is then transformed through hydroxypyruvate andglycerate to enter central metabolism at phosphoglycerate. To examine itsuse of the serine-isocitrate lyase pathway under anaerobic conditions, wegrew S. oneidensis MR-1 on [1-13C]lactate as the sole carbon source witheither trimethylamine N-oxide (TMAO) or fumarate as an electron acceptor.Analysis of cellular metabolites indicates that a large percentage(>75 percent) of lactate was partially oxidized to either acetate orpyruvate. The 13C isotope distributions in amino acids and other keymetabolites indicate that, under anaerobic conditions, a complete serinepathway is not present, and lactate is oxidized via a highly reversibleserine degradation pathway. The labeling data also suggest significantactivity in the anaplerotic (malic enzyme and phosphoenolpyruvatecarboxylase) and glyoxylate shunt (isocitrate lyase and malate synthase)reactions. Although the tricarboxylic acid (TCA) cycle is often observedto be incomplete in many other anaerobes (absence of 2-oxoglutaratedehydrogenase activity), isotopic labeling supports the existence of acomplete TCA cycle in S. oneidensis MR-1 under TMAO reductioncondition.
Date: July 11, 2006
Creator: Tang, Yinjie; Pingitore, Francesco; Mukhopadhyay, Aindrila; Phan,Richard; Hazen, Terry C. & Keasling, Jay D.
System: The UNT Digital Library
MODEL-BASED HYDROACOUSTIC BLOCKAGE ASSESSMENT AND DEVELOPMENT OF AN EXPLOSIVE SOURCE DATABASE (open access)

MODEL-BASED HYDROACOUSTIC BLOCKAGE ASSESSMENT AND DEVELOPMENT OF AN EXPLOSIVE SOURCE DATABASE

We are continuing the development of the Hydroacoustic Blockage Assessment Tool (HABAT) which is designed for use by analysts to predict which hydroacoustic monitoring stations can be used in discrimination analysis for any particular event. The research involves two approaches (1) model-based assessment of blockage, and (2) ground-truth data-based assessment of blockage. The tool presents the analyst with a map of the world, and plots raypath blockages from stations to sources. The analyst inputs source locations and blockage criteria, and the tool returns a list of blockage status from all source locations to all hydroacoustic stations. We are currently using the tool in an assessment of blockage criteria for simple direct-path arrivals. Hydroacoustic data, predominantly from earthquake sources, are read in and assessed for blockage at all available stations. Several measures are taken. First, can the event be observed at a station above background noise? Second, can we establish backazimuth from the station to the source. Third, how large is the decibel drop at one station relative to other stations. These observational results are then compared with model estimates to identify the best set of blockage criteria and used to create a set of blockage maps for each station. The …
Date: July 11, 2005
Creator: Matzel, E; Ramirez, A & Harben, P
System: The UNT Digital Library
Linearly Scaling 3D Fragment Method for Large-Scale Electronic Structure Calculations (open access)

Linearly Scaling 3D Fragment Method for Large-Scale Electronic Structure Calculations

We present a new linearly scaling three-dimensional fragment (LS3DF) method for large scale ab initio electronic structure calculations. LS3DF is based on a divide-and-conquer approach, which incorporates a novel patching scheme that effectively cancels out the artificial boundary effects due to the subdivision of the system. As a consequence, the LS3DF program yields essentially the same results as direct density functional theory (DFT) calculations. The fragments of the LS3DF algorithm can be calculated separately with different groups of processors. This leads to almost perfect parallelization on tens of thousands of processors. After code optimization, we were able to achieve 35.1 Tflop/s, which is 39percent of the theoretical speed on 17,280 Cray XT4 processor cores. Our 13,824-atom ZnTeO alloy calculation runs 400 times faster than a direct DFTcalculation, even presuming that the direct DFT calculation can scale well up to 17,280 processor cores. These results demonstrate the applicability of the LS3DF method to material simulations, the advantage of using linearly scaling algorithms over conventional O(N3) methods, and the potential for petascale computation using the LS3DF method.
Date: July 1, 2008
Creator: Wang, Lin-Wang; Lee, Byounghak; Shan, Hongzhang; Zhao, Zhengji; Meza, Juan; Strohmaier, Erich et al.
System: The UNT Digital Library
Light-Front Holography and Hadronization at the Amplitude Level (open access)

Light-Front Holography and Hadronization at the Amplitude Level

The correspondence between theories in anti-de Sitter space and conformal field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. Light-front holography is a remarkable feature of AdS/CFT: it allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates and the behavior of the QCD coupling in the infrared. We suggest that the spatial support of QCD condensates is restricted to the interior of hadrons, since they arise due to the interactions of confined quarks and gluons. Chiral symmetry is thus broken in a limited domain of size 1=m{sub {pi}} in analogy to the limited physical extent of superconductor phases. A new method for computing the hadronization of quark and gluon jets at the amplitude level, an event amplitude generator, is outlined.
Date: July 25, 2008
Creator: Brodsky, Stanley J.; de Teramond, Guy & Shrock, Robert
System: The UNT Digital Library
Multizone Age-of-Air Analysis (open access)

Multizone Age-of-Air Analysis

Age of air is a technique for evaluating ventilation that has been actively used for over 20 years. Age of air quantifies the time it takes for outdoor air to reach a particular location or zone within then indoor environment. Age of air is often also used to quantify the ventilation effectiveness with respect to indoor air quality. In a purely single zone situation this use of age of air is straightforward, but application of age of air techniques in the general multizone environment has not been fully developed. This article looks at expanding those single-zone techniques to the more complicated environment of multizone buildings and in doing so develops further the general concept of age of air. The results of this analysis shows that the nominal age of air as often used cannot be directly used for determining ventilation effectiveness unless specific assumptions are made regarding source distributions.
Date: July 1, 2007
Creator: Sherman, Max H.
System: The UNT Digital Library
Entropy of near-extremal black holes in AdS5 (open access)

Entropy of near-extremal black holes in AdS5

We construct the microstates of near-extremal black holes in AdS_5 x S5 as gases of defects distributed in heavy BPS operators in the dual SU(N) Yang-Mills theory. These defects describe open strings on spherical D3-branes in the S5, and we show that they dominate the entropy by directly enumerating them and comparing the results with a partition sum calculation. We display new decoupling limits in which the field theory of the lightest open strings on the D-branes becomes dual to a near-horizon region of the black hole geometry. In the single-charge black hole we find evidence for an infrared duality between SU(N) Yang-Mills theories that exchanges the rank of the gauge group with an R-charge. In the two-charge case (where pairs of branes intersect on a line), the decoupled geometry includes an AdS_3 factor with a two-dimensional CFT dual. The degeneracy in this CFT accounts for the black hole entropy. In the three-charge case (where triples of branes intersect at a point), the decoupled geometry contains an AdS_2 factor. Below a certain critical mass, the two-charge system displays solutions with naked timelike singularities even though they do not violate a BPS bound. We suggest a string theoretic resolution of these …
Date: July 24, 2007
Creator: Simon, Joan; Balasubramanian, Vijay; de Boer, Jan; Jejjala, Vishnu & Simon, Joan
System: The UNT Digital Library
Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks (open access)

Deinococcus geothermalis: The Pool of Extreme Radiation Resistance Genes Shrinks

Bacteria of the genus Deinococcus are extremely resistant to ionizing radiation (IR), ultraviolet light (UV) and desiccation. The mesophile Deinococcus radiodurans was the first member of this group whose genome was completely sequenced. Analysis of the genome sequence of D. radiodurans, however, failed to identify unique DNA repair systems. To further delineate the genes underlying the resistance phenotypes, we report the whole-genome sequence of a second Deinococcus species, the thermophile Deinococcus geothermalis, which at itsoptimal growth temperature is as resistant to IR, UV and desiccation as D. radiodurans, and a comparative analysis of the two Deinococcus genomes. Many D. radiodurans genes previously implicated in resistance, but for which no sensitive phenotype was observed upon disruption, are absent in D. geothermalis. In contrast, most D. radiodurans genes whose mutants displayed a radiation-sensitive phenotype in D. radiodurans are conserved in D. geothermalis. Supporting the existence of a Deinococcus radiation response regulon, a common palindromic DNA motif was identified in a conserved set of genes associated with resistance, and a dedicated transcriptional regulator was predicted. We present the case that these two species evolved essentially the same diverse set of gene families, and that the extreme stress-resistance phenotypes of the Deinococcus lineage emerged …
Date: July 24, 2007
Creator: Makarova, Kira S.; Omelchenko, Marina V.; Gaidamakova, Elena K.; Matrosova, Vera Y.; Vasilenko, Alexander; Zhai, Min et al.
System: The UNT Digital Library
Rh(I)-Catalyzed Direct Arylation of Pyridines and Quinolines (open access)

Rh(I)-Catalyzed Direct Arylation of Pyridines and Quinolines

The pyridine and quinoline nuclei are privileged scaffolds that occupy a central role in many medicinally relevant compounds. Consequently, methods for their expeditious functionalization are of immediate interest. However, despite the immense importance of transition-metal catalyzed cross-coupling for the functionalization of aromatic scaffolds, general solutions for coupling 2-pyridyl organometallics with aryl halides have only recently been presented. Direct arylation at the ortho position of pyridine would constitute an even more efficient approach because it eliminates the need for the stoichiometric preparation and isolation of 2-pyridyl organometallics. Progress towards this goal has been achieved by activation of the pyridine nucleus for arylation via conversion to the corresponding pyridine N-oxide or N-iminopyridinium ylide. However, this approach necessitates two additional steps: activation of the pyridine or quinoline starting material, and then unmasking the arylated product. The use of pyridines directly would clearly represent the ideal situation both in terms of cost and simplicity. We now wish to document our efforts in this vein, culminating in an operationally simple Rh(I)-catalyzed direct arylation of pyridines and quinolines. We recently developed an electron-rich Rh(I) system for catalytic alkylation at the ortho position of pyridines and quinolines with alkenes. Therefore, we initially focused our attention on the …
Date: July 29, 2008
Creator: Berman, Ashley; Lewis, Jared; Bergman, Robert & Ellman, Jonathan
System: The UNT Digital Library