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Geometrical dependence of the low-frequency noise in superconducting flux qubits (open access)

Geometrical dependence of the low-frequency noise in superconducting flux qubits

Article reporting on a study of a series of 85 devices of vary design using a general method for directly measuring the low-frequency flux noise (below 10 Hz) in compound Josephson-junction superconducting flux qubits. The results support the hypothesis that local impurities in the vicinity of the qubit wiring are a key source of low-frequency flux noise in superconducting devices.
Date: February 26, 2009
Creator: Lanting, T.; Berkley, A. J.; Bumble, B.; Bunyk, P.; Fung, A.; Johansson, J. et al.
System: The UNT Digital Library
Prodrugs of Thyrotropin-Releasing Hormone and Related Peptides as Central Nervous System Agents (open access)

Prodrugs of Thyrotropin-Releasing Hormone and Related Peptides as Central Nervous System Agents

This article is a review of prodrug design for brain delivery of small- and medium-sized neuropeptides, focusing on thyrotropin-releasing hormone and structurally related peptides as examples.
Date: February 6, 2009
Creator: Prokai-Tatrai, Katalin & Prókai, László, 1958-
System: The UNT Digital Library
An Updating System for the Gridded Population Database of China Based on Remote Sensing, GIS and Spatial Database Technologies (open access)

An Updating System for the Gridded Population Database of China Based on Remote Sensing, GIS and Spatial Database Technologies

Describes the development of a Spatial Population Updating System (SPUS) for updating the gridded population database of China based on remote sensing, GIS and spatial database technologies, with a spatial resolution of 1 km by 1 km.
Date: February 20, 2009
Creator: Yang, Xiaohuan; Huang, Yaohuan; Dong, Pinliang; Jiang, Dong & Liu, Honghui
System: The UNT Digital Library
Multicultural Center in the News, October 26, 2005 (open access)

Multicultural Center in the News, October 26, 2005

A document about a story in the NT Daily that uses quotes from members of the UNT Multicultural Center. It is titled "Campus, nation mourn civil rights icon - Effects of Park's death felt by university community". There is also a picture of Parks being fingerprinted after her arrest at the bottom.
Date: February 22, 2006
Creator: University of North Texas. Multicultural Center.
System: The UNT Digital Library
Multicultural Center in the News, April 1, 2005 (open access)

Multicultural Center in the News, April 1, 2005

A document about a story in the NT Daily that covers a UNT Multicultural Center Event. It is titled "Women of Color conference focuses on unity". There is also a picture of panelists at the event.
Date: February 22, 2006
Creator: University of North Texas. Multicultural Center.
System: The UNT Digital Library
Multicultural Center in the News, October 12, 2005 (open access)

Multicultural Center in the News, October 12, 2005

A document about a story in the NT Daily that covers a UNT Multicultural Center Event. It is titled "'Celebración' showcases Hispanic Heritage month with banquet". There is also a picture of two students at the event.
Date: February 22, 2002
Creator: University of North Texas. Multicultural Center.
System: The UNT Digital Library
Multicultural Center in the News, October 7, 2005 (open access)

Multicultural Center in the News, October 7, 2005

A document about a story in the NT Daily that covers a screening of the film "Honk if You Love Buddha" at UNT as part of the first Asian Student Leadership Conference. The article is titled "Asian leadership conference to unite, debunk stereotypes".
Date: February 22, 2006
Creator: University of North Texas. Multicultural Center.
System: The UNT Digital Library
Multicultural Center in the News, October 12, 2005 (open access)

Multicultural Center in the News, October 12, 2005

A document about a story in the NT Daily that covers segregation issues in the pan-hellenic community. It is titled "Greeks viewed as segregated" and includes a picture of the Delta Theta Sorority at UNT.
Date: February 22, 2006
Creator: University of North Texas. Multicultural Center.
System: The UNT Digital Library
Large plasma pressure perturbations and radial convective transport in a tokamak (open access)

Large plasma pressure perturbations and radial convective transport in a tokamak

Strongly localized plasma structures with large pressure inhomogeneities (such as plasma blobs in the scrape-off-layer (SOL)/shadow regions, pellet clouds, ELMs) observed in the tokamaks, stellarators and linear plasma devices. Experimental studies of these phenomena reveal striking similarities including more convective rather than diffusive radial plasma transport. We suggest that rather simple models can describe many essentials of blobs, ELMs, and pellet clouds dynamics. The main ingredient of these models is the effective plasma gravity caused by magnetic curvature, centrifugal or friction forces effects. As a result, the equations governing plasma transport in such localized structures appear to be rather similar to that used to describe nonlinear evolution of thermal convection in the Boussinesq approximation (directly related to the Rayleigh-Taylor instability).
Date: February 4, 2004
Creator: Krasheninnikov, S.; Ryutov, D. & Yu, G.
System: The UNT Digital Library
Properties of High Efficiency CIGS Thin Film Solar Cells (open access)

Properties of High Efficiency CIGS Thin Film Solar Cells

We present experimental results in three areas. Solar cells with an efficiency of 19% have been fabricated with an absorber bandgap in the range of 1.1-1.2 eV. Properties of solar cells fabricated with and without an undoped ZnO layer were compared. The data show that high efficiency cells can be fabricated without using the high-resistivity or undoped ZnO layer. Properties of CIGS solar cells were fabricated from thin absorbers (1 {micro}m) deposited by the three-stage process and simultaneous co-deposition of all the elements. In both cases, solar cells with efficiencies of 16%-17% are obtained.
Date: February 1, 2005
Creator: Ramanathan, K.; Keane, J. & Noufi, R.
System: The UNT Digital Library
Reduction of laser beam spray at 0.527 (micron)m in an ignition scale length plasma with temporal beam smoothing (open access)

Reduction of laser beam spray at 0.527 (micron)m in an ignition scale length plasma with temporal beam smoothing

We have measured the effect of laser smoothing by spectral dispersion (SSD) on beam spray, transmission and deflection of a 2{omega} (527 nm) high intensity (10{sup 15} W/cm{sup 2}) interaction beam through an underdense large scale length plasma. We observe a 40% reduction of the beam spray when SSD is used, consistent with modeling by a fluid laser-plasma interaction code (pF3d). We measured a decrease in beam transmission with increasing laser intensity, consistent with the onset of parametric instabilities.
Date: February 4, 2004
Creator: Niemann, C.; Divol, L.; Froula, D. H.; Glenzer, S. H.; Gregori, G.; Kirkwood, R. K. et al.
System: The UNT Digital Library
a-SiGe:H Materials and Devices Deposited by Hot Wire CVD Using a Tantalum Filament Operated at Low Temperature (open access)

a-SiGe:H Materials and Devices Deposited by Hot Wire CVD Using a Tantalum Filament Operated at Low Temperature

We report the deposition of improved hydrogenated amorphous silicon germanium (a-SiGe:H) films by the hot wire CVD (HWCVD) technique using a tantalum filament operating at a low temperature. We gauge the material quality of the a-SiGe:H films by comparing infrared, small angle X-ray scattering (SAXS), photocapacitance, and conductivity measurements to earlier results, and fabricate single-junction n-i-p solar cell devices using these i-layers.
Date: February 1, 2005
Creator: Mahan, A. H.; Xu, Y.; Gedvilas, L. M.; Reedy, R. C.; Williamson, D. L.; Datta, S. et al.
System: The UNT Digital Library
A Simple test for the existence of two accretion modes in active galactic nuclei (open access)

A Simple test for the existence of two accretion modes in active galactic nuclei

By analogy to the different accretion states observed in black-hole X-ray binaries (BHXBs), it appears plausible that accretion disks in active galactic nuclei (AGN) undergo a state transition between a radiatively efficient and inefficient accretion flow. If the radiative efficiency changes at some critical accretion rate, there will be a change in the distribution of black hole masses and bolometric luminosities at the corresponding transition luminosity. To test this prediction, the author considers the joint distribution of AGN black hole masses and bolometric luminosities for a sample taken from the literature. The small number of objects with low Eddington-scaled accretion rates m < 0.01 and black hole masses M{sub BH} < 10{sup 9} M{sub {circle_dot}} constitutes tentative evidence for the existence of such a transition in AGN. Selection effects, in particular those associated with flux-limited samples, systematically exclude objects in particular regions of the (M{sub BH}, L{sub bol}) plane. Therefore, they require particular attention in the analysis of distributions of black hole mass, bolometric luminosity, and derived quantities like the accretion rate. The author suggests further observational tests of the BHXB-AGN unification scheme which are based on the jet domination of the energy output of BHXBs in the hard state, …
Date: February 1, 2005
Creator: Jester, Sebastian
System: The UNT Digital Library
Interconnection Testing of Distributed Resources: Preprint (open access)

Interconnection Testing of Distributed Resources: Preprint

With the publication of IEEE 1547-2003(TM) Standard for Interconnecting Distributed Resources With Electric Power Systems, the electric power industry has a need to develop tests and procedures to verify that interconnection equipment meets 1547 technical requirements. A new standard, IEEE P1547.1(TM), is being written to give detailed tests and procedures for confirming that equipment meets the interconnection requirements. The National Renewable Energy Laboratory has been validating test procedures being developed as part of IEEE P1547.1. As work progresses on the validation of those procedures, information and test reports are passed on to the working group of IEEE P1547.1 for future revisions.
Date: February 1, 2004
Creator: Kroposki, B.; Basso, T. & DeBlasio, R.
System: The UNT Digital Library
A Source-to-Source Architecture for User-Defined Optimizations (open access)

A Source-to-Source Architecture for User-Defined Optimizations

The performance of object-oriented applications often suffers from the inefficient use of high-level abstractions provided by underlying libraries. Since these library abstractions are user-defined and not part of the programming language itself only limited information on their high-level semantics can be leveraged through program analysis by the compiler and thus most often no appropriate high-level optimizations are performed. In this paper we outline an approach based on source-to-source transformation to allow users to define optimizations which are not performed by the compiler they use. These techniques are intended to be as easy and intuitive as possible for potential users; i.e. for designers of object-oriented libraries, people most often only with basic compiler expertise.
Date: February 6, 2003
Creator: Schordan, M & Quinlan, D
System: The UNT Digital Library
Reviewers Comments on the 5th Symposium and the Status of Fusion Research 2003 (open access)

Reviewers Comments on the 5th Symposium and the Status of Fusion Research 2003

Better to understand the status of fusion research in the year 2003 we will first put the research in its historical context. Fusion power research, now beginning its sixth decade of continuous effort, is unique in the field of scientific research. Unique in its mixture of pure and applied research, unique in its long-term goal and its promise for the future, and unique in the degree that it has been guided and constrained by national and international governmental policy. Though fusion research's goal has from the start been precisely defined, namely, to obtain a net release of energy from controlled nuclear fusion reactions between light isotopes (in particular those of hydrogen and helium) the difficulty of the problem has spawned in the past a very wide variety of approaches to the problem. Some of these approaches have had massive international support for decades, some have been pursued only at a ''shoestring'' level by dedicated groups in small research laboratories or universities. In discussing the historical and present status of fusion research the implications of there being two distinctly different approaches to achieving net fusion power should be pointed out. The first, and oldest, approach is the use of strong magnetic …
Date: February 3, 2005
Creator: Post, R F
System: The UNT Digital Library
Inversion of Synthetic Aperture Radar Interferograms for Sources of Production-Related Subsidence at the Dixie Valley Geothermal Field (open access)

Inversion of Synthetic Aperture Radar Interferograms for Sources of Production-Related Subsidence at the Dixie Valley Geothermal Field

We used synthetic aperture radar interferograms to image ground subsidence that occurred over the Dixie Valley geothermal field during different time intervals between 1992 and 1997. Linear elastic inversion of the subsidence that occurred between April, 1996 and March, 1997 revealed that the dominant sources of deformation during this time period were large changes in fluid volumes at shallow depths within the valley fill above the reservoir. The distributions of subsidence and subsurface volume change support a model in which reduction in pressure and volume of hot water discharging into the valley fill from localized upflow along the Stillwater range frontal fault is caused by drawdown within the upflow zone resulting from geothermal production. Our results also suggest that an additional source of fluid volume reduction in the shallow valley fill might be similar drawdown within piedmont fault zones. Shallow groundwater flow in the vicinity of the field appears to be controlled on the NW by a mapped fault and to the SW by a lineament of as yet unknown origin.
Date: February 7, 2003
Creator: Foxall, W & Vasco, D
System: The UNT Digital Library
Speckle Imaging of Titan at 2 microns: Surface Albedo, Haze Optical Depth, and Tropospheric Clouds 1996-1998 (open access)

Speckle Imaging of Titan at 2 microns: Surface Albedo, Haze Optical Depth, and Tropospheric Clouds 1996-1998

We present results from 14 nights of observations of Titan in 1996-1998 using near-infrared (centered at 2.1 microns) speckle imaging at the 10-meter W.M. Keck Telescope. The observations have a spatial resolution of 0.06 arcseconds. We detect bright clouds on three days in October 1998, with a brightness about 0.5% of the brightness of Titan. Using a 16-stream radiative transfer model (DISORT) to model the central equatorial longitude of each image, we construct a suite of surface albedo models parameterized by the optical depth of Titan's hydrocarbon haze layer. From this we conclude that Titan's equatorial surface albedo has plausible values in the range of 0-0.20. Titan's minimum haze optical depth cannot be constrained from this modeling, but an upper limit of 0.3 at this wavelength range is found. More accurate determination of Titan's surface albedo and haze optical depth, especially at higher latitudes, will require a model that fully considers the 3-dimensional nature of Titan's atmosphere.
Date: February 11, 2004
Creator: Gibbard, S. G.; Gavel, D.; Ghez, A. M.; de Pater, I.; Max, C. E.; Young, E. F. et al.
System: The UNT Digital Library
Adapting high-resolution speckle imaging to moving targets and platforms (open access)

Adapting high-resolution speckle imaging to moving targets and platforms

High-resolution surveillance imaging with apertures greater than a few inches over horizontal or slant paths at optical or infrared wavelengths will typically be limited by atmospheric aberrations. With static targets and static platforms, we have previously demonstrated near-diffraction limited imaging of various targets including personnel and vehicles over horizontal and slant paths ranging from less than a kilometer to many tens of kilometers using adaptations to bispectral speckle imaging techniques. Nominally, these image processing methods require the target to be static with respect to its background during the data acquisition since multiple frames are required. To obtain a sufficient number of frames and also to allow the atmosphere to decorrelate between frames, data acquisition times on the order of one second are needed. Modifications to the original imaging algorithm will be needed to deal with situations where there is relative target to background motion. In this paper, we present an extension of these imaging techniques to accommodate mobile platforms and moving targets.
Date: February 5, 2004
Creator: Carrano, C J & Brase, J M
System: The UNT Digital Library
12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Summary Discussion Sessions (open access)

12th Workshop on Crystalline Silicon Solar Cell Materials and Processes: Summary Discussion Sessions

This report is a summary of the discussion sessions of the 12th Workshop on Crystalline Silicon Solar Cells and Processes. The theme of the workshop was"Fundamental R&D in c-Si: Enabling Progress in Solar-Electric Technology." This theme was chosen to reflect a concern that the current expansion in the PV energy production may redirect basic research efforts to production-oriented issues. The PV industry is installing added production capacity and new production lines that include the latest technologies. Once the technologies are selected, it is difficult to make changes. Consequently, a large expansion can stagnate the technologies and diminish interest in fundamental research. To prevent the fundamental R&D program from being overwhelmed by the desire to address immediate engineering issues, there is a need to establish topics of fundamental nature that can be pursued by the universities and the research institutions. Hence, one of the objectives of the workshop was to identify such areas for fundamental research.
Date: February 1, 2003
Creator: Sopori, B.; Swanson, D.; Sinton, R. & Tan, T.
System: The UNT Digital Library
In-Situ TEM Observations of Interface Sliding and Migration in a Refined Lamellar TiAl Alloy (open access)

In-Situ TEM Observations of Interface Sliding and Migration in a Refined Lamellar TiAl Alloy

The stability of lamellar interfaces in lamellar TiAl by straining at ambient temperatures has been investigated using in-situ straining techniques performed in a transmission electron microscope in order to obtain direct evidence to support the previously proposed creep mechanisms in refined lamellar TiAl based upon the interface sliding in association with the cooperative motion of interfacial dislocations. The results have revealed that both sliding and migration of lamellar interfaces can take place as a result of the cooperative motion of interfacial dislocations.
Date: February 18, 2004
Creator: Schwartz, A J; Nieh, T G & Hsiung, L M
System: The UNT Digital Library
Metastable metallic hydrogen glass (open access)

Metastable metallic hydrogen glass

The quest for metallic hydrogen has been going on for over one hundred years. Before hydrogen was first condensed into a liquid in 1898, it was commonly thought that condensed hydrogen would be a metal, like the monatomic alkali metals below hydrogen in the first column of the Periodic Table. Instead, condensed hydrogen turned out to be transparent, like the diatomic insulating halogens in the seventh column of the Periodic Table. Wigner and Huntington predicted in 1935 that solid hydrogen at 0 K would undergo a first-order phase transition from a diatomic to a monatomic crystallographically ordered solid at {approx}25 GPa. This first-order transition would be accompanied by an insulator-metal transition. Though searched for extensively, a first-order transition from an ordered diatomic insulator to a monatomic metal is yet to be observed at pressures up to 120 and 340 GPa using x-ray diffraction and visual inspection, respectively. On the other hand, hydrogen reaches the minimum electrical conductivity of a metal at 140 GPa, 0.6 g/cm{sup 3}, and 3000 K. These conditions were achieved using a shock wave reverberating between two stiff sapphire anvils. The shock wave was generated with a two-stage light-gas gun. This temperature exceeds the calculated melting temperature …
Date: February 6, 2001
Creator: Nellis, W J
System: The UNT Digital Library
Statistical Stability and Time-Reversal Imgaing in Random Media (open access)

Statistical Stability and Time-Reversal Imgaing in Random Media

Localization of targets imbedded in a heterogeneous background medium is a common problem in seismic, ultrasonic, and electromagnetic imaging problems. The best imaging techniques make direct use of the eigenfunctions and eigenvalues of the array response matrix, as recent work on time-reversal acoustics has shown. Of the various imaging functionals studied, one that is representative of a preferred class is a time-domain generalization of MUSIC (MUltiple Signal Classification), which is a well-known linear subspace method normally applied only in the frequency domain. Since statistical stability is not characteristic of the frequency domain, a transform back to the time domain after first diagonalizing the array data in the frequency domain takes optimum advantage of both the time-domain stability and the frequency-domain orthogonality of the relevant eigenfunctions.
Date: February 5, 2002
Creator: Berryman, J; Borcea, L; Papanicolaou, G & Tsogka, C
System: The UNT Digital Library
Slow Nonradiative Decay for Rare Earths in KPb2Br5 and RbPb2Br5 (open access)

Slow Nonradiative Decay for Rare Earths in KPb2Br5 and RbPb2Br5

We report on spectroscopic investigations of Nd{sup 3+}- and Tb{sup 3+}- doped low phonon energy, moisture-resistant host crystals, KPb{sub 2}Br{sub 5} and RbPb{sub 2}Br{sub 5}, and their potential to serve as new solid state laser materials at new wavelengths, especially in the long wavelength infrared region. This includes emission spectra, emission lifetime measurements, Raman scattering spectra as well as calculations of the multiphonon decay rate, radiative lifetimes and quantum efficiencies for relevant (laser) transitions in these crystals.
Date: February 27, 2004
Creator: Rademaker, K.; Petermann, K.; Huber, G.; Krupke, W.; Page, R.; Payne, S. et al.
System: The UNT Digital Library