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Development of techniques in magnetic resonance and structural studies of the prion protein

Description: Magnetic resonance is the most powerful analytical tool used by chemists today. Its applications range from determining structures of large biomolecules to imaging of human brains. Nevertheless, magnetic resonance remains a relatively young field, in which many techniques are currently being developed that have broad applications. In this dissertation, two new techniques are presented, one that enables the determination of torsion angles in solid-state peptides and proteins, and another that in… more
Date: July 1, 2000
Creator: Bitter, Hans-Marcus L.
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries Government Documents Department
open access

Surface and Borehole Electromagnetic Imaging of Conducting Contaminant Plumes

Description: Electromagnetic induction tomography is a promising new tool for imaging electrical conductivity variations in the earth. The source field is a magnetic field generated by currents in wire coils. This source field is normally produced in one borehole, while the received signals are the measured small changes in magnetic field in another, distant borehole; however, the method may also be used successfully in combination with surface sources and receivers. The goal of this procedure is to image e… more
Date: June 1, 2000
Creator: Berryman, James G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High Frequency Electromagnetic Impedance Measurements For Characterization, Monitoring And Verification Efforts

Description: Electromagnetic methods in exploration geophysics include many technologies capable of imaging the subsurface. The electromagnetic geophysical spectrum for shallow subsurface imaging is roughly 1 Hz to 500 MHz, with electrical resistivity and other geometric sounding methods located at the low frequency end and the familiar GPR method at the high end of the spectrum. Baseline studies (Pellerin et al., 1997) show that electromagnetic instrumentation in the mid- and low-frequencies (< 300 kHz)… more
Date: December 31, 2000
Creator: Lee, Ki Ha & Becker, Alex
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Analysis of the Magnetic Field Measured by a Rotating Hall Probe in a Solenoid to Locate its Magnetic Axis

Description: We have analyzed the motion of a Hall probe, which is rotated about an axis that is arbitrarily displaced and oriented with respect to the magnetic axis of a solenoid. We outline how the magnetic field measured by the rotating Hall probe can be calculated. We show how to compare theoretical results with actual measurements, to determine the displacement and orientation of the axis of rotation of the probe from the magnetic axis. If the center of rotation of the probe is known by surveying, the … more
Date: November 6, 2000
Creator: Kponou, A.; Pikin, A.; Beebe, E. & Alessi, J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Integration of Radiation-Hard Magnetic Random Access Memory with CMOS ICs

Description: The research undertaken in this LDRD-funded project addressed the joint development of magnetic material-based nonvolatile, radiation-hard memory cells with Sandia National Laboratory. Specifically, the goal of this project was to demonstrate the intrinsic radiation-hardness of Giant Magneto-Resistive (GMR) materials by depositing representative alloy combinations upon radiation-hardened silicon-based integrated circuits. All of the stated goals of the project were achieved successfully. The ne… more
Date: February 15, 2000
Creator: Cerjan, C. J. & Sigmon, T. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Status of the U.S. Dark Matter Axion Search

Description: We describe the status of a sensitive search for halo axions with masses in the {mu}eV range. A tunable large-volume and low-loss microwave cavity is operated at low temperature in a strong magnetic field. Resonant Primakoff conversion of axions into photons takes place when the cavity frequency is matched to the axion mass. No positive signal has been found so far, and we are able to exclude hadronic axions as the dominant halo component over a significant axion mass range. Future plans for a … more
Date: October 4, 2000
Creator: Hagmann, C.; Asztalos, S.; Daw, E.; Golubev, N. A.; Kinion, D.; Moltz, D. M. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The Inductrack Approach to Magnetic Levitation

Description: Concepts developed during research on passive magnetic bearing systems at the Lawrence Livermore National Laboratory gave rise to a new approach to magnetic levitation, the Inductrack. A passive induced-current system employing permanent magnets on the moving vehicle, the Inductrack maximizes levitation forces by a combination of two elements. First, the permanent magnets on the vehicle are arranged in a ''Halbach array,'' a magnet configuration that optimally produces a periodic magnetic field… more
Date: April 19, 2000
Creator: Post, R. F. & Ryutov, D. D.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Integrated Neutral Beam Measurements in a Tokamak Environment

Description: Tokamaks are, in many respects, the most promising avenue for the development of fusion power. The continual improvement in the performance of these devices and their understanding of them is due in greater measure to the development of accurate plasma diagnostics. Many of the most crucial measurements required to assess their progress on these experiments are based in one way or another upon collisional interactions of injected neutral beams with the plasma. These measurements include such fun… more
Date: September 1, 2000
Creator: Thomas, D. M.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Estimate of Magnetic Forces on Beam Sweeping Kickers

Description: The beam sweeping magnet kickers are two pairs of conductors placed 90 degrees apart inside a circular magnetic yoke. Each pair has the same excitation current in the opposite directions, and the two currents are a sine and a cosine in phase. To estimate the magnetic forces on the kickers due to the excitation currents, we make the following simplifications: (1) The four conductors are all parallel to one another; (2) There are no relative motions within the system; and (3) the magnetic yoke ha… more
Date: February 23, 2000
Creator: Hu, Martin & U., /Nebraska
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Surface-to-Borehole and Surface Electromagnetic Surveys at the Hanford Leak Experiment

Description: This is a preliminary report detailing the electromagnetic (EM) surveys and data interpretation for the leak experiment at the Hanford site. Two types of EM surveys were planned for the Hanford leak experiment held between June 5 and July 23, 2000. One survey used surface EM transmitters and borehole vertical magnetic field receivers (surface to borehole). Another survey consisted only of surface measurements, where an EM transmitter was located on the surface, and EM impedance measurements (co… more
Date: August 1, 2000
Creator: Hoversten, Gary M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Users manual for the UEDGE edge-plasma transport code

Description: Operational details are given for the two-dimensional UEDGE edge-plasma transport code. The model applies to nearly fully-ionized plasmas in a strong magnetic field. Equations are solved for the plasma density, velocity along the magnetic field, electron temperature, ion temperature, and electrostatic potential. In addition, fluid models of neutrals species are included or the option to couple to a Monte Carlo code description of the neutrals. Multi-species ion mixtures can be simulated. The ph… more
Date: January 10, 2000
Creator: Rognlien, T. D.; Rensink, M. E. & Smith, G. R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Dipole septum magnet in the fast kicker system for multi-axis advanced radiography

Description: Here we present designs for a static septum magnet with two adjacent apertures where ideally one aperture has a uniform dipole field and the other zero field. Two designs are considered. One is a true septum magnet with a thin layer of coils and materials separating the dipole field region from the null field region. During the beam switching process, the intense electron beam will spray across this material septum leading to concerns on beam control, vacuum quality, radiation damage, etc. due … more
Date: August 10, 2000
Creator: Wang, L.; Lund, S. M. & Poole, B. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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ALTERNATING CURRENT LOSSES IN AG-SHEATHED BSCCO (2212 AND 2223) TAPES AND WIRES AND YBCO (123) COATED CONDUCTORS

Description: In this study, we focus on the examination of ac losses in conductors utilizing Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O [BSCCO (2223)] high TC superconductors (HTS). In addition, we seek to assist other facilities such as the University of Wisconsin-Madison Applied Superconductivity Center (UW-ASC), Brookhaven National Laboratory, and other DoE facilities investigating the use of HTS in electric power applications (e.g., generators, motors, and transformers). To accomplish this we will develop an… more
Date: January 1, 2000
Creator: Hurley, John S.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Final Report Sustained Spheromak Physics Project FY 1997 - FY 1999

Description: This is the final report on the LDRD SI-funded Sustained Spheromak Physics Project for the years FY1997-FY1999, during which the SSPX spheromak was designed, built, and commissioned for operation at LLNL. The specific LDRD project covered in this report concerns the development, installation, and operation of specialized hardware and diagnostics for use on the SSPX facility in order to study energy confinement in a sustained spheromak plasma configuration. The USDOE Office of Fusion Energy Scie… more
Date: February 29, 2000
Creator: Hooper, E.B. & Hill, D.N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

AC losses in conductors based on high {Tc} superconductors

Description: In electrical power devices, ac losses from a superconductor is a primary factor which determines their usefulness as commercial power equipment. For this reason, extensive studies have been carried out on the losses of Bi{sub 2}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10}/Ag, [Bi(2223)/Ag], tapes. These studies were mostly limited to a single isolated tape. However, a conductor in a power device is surrounded by other conductors and the precise magnetic field distribution around it is very different f… more
Date: March 17, 2000
Creator: Suenaga, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Magnetoconductance of Independently Tunable Tunnel-Coupled Double Quantum Wires

Description: The authors report on their recent experimental studies of vertically-coupled quantum point contacts subject to in-plane magnetic fields. Using a novel flip-chip technique, mutually aligned split gates on both sides of a sub micron thick double quantum well heterostructure define a closely-coupled pair of ballistic one-dimensional (1D) constrictions. They observe quantized conductance steps due to each quantum well and demonstrate independent control of each ID constriction width. In addition, … more
Date: July 13, 2000
Creator: Blount, Mark A.; Moon, J. S.; Simmons, Jerry A.; Lyo, Sungkwun K.; Wendt, Joel R. & Reno, John L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Neutrino oscillation appearance experiment using nuclear emulsion and magnetized iron

Description: This report describes an apparatus that could be used to measure both the identity and charge of an outgoing lepton in a charged current neutrino interaction. This capability in a massive detector would allow the most comprehensive set of neutrino oscillation physics measurements. By measuring the six observable transitions between initial and final state neutrinos, one would be able to measure all elements of the neutrino mixing matrix, as well as search for CP violation, and matter effects. I… more
Date: January 24, 2000
Creator: Harris, D.A. & Para, A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Unusual magnetic quantum oscillations in organic metals at high magnetic fields

Description: The authors report on Shubnikov-de Haas (SdH) and de Haas-van Alphen (dHvA) results for the highly two-dimensional (2D) organic superconductors {kappa}-(ET){sub 2}I{sub 3} ({Tc} = 3.5 K) and {beta}{double_prime}-(ET){sub 2}SF{sub 5}CH{sub 2}CF{sub 2}SO{sub 3} ({Tc} = 4.4 K). The SdH oscillations of both materials show an apparent deviation from the well-understood 2D dHvA signal at low temperatures and high magnetic fields. For {kappa}-(ET){sub 2}I{sub 3}, the mechanism leading to this behavior… more
Date: April 4, 2000
Creator: Wosnitza, J.; Wanka, S.; Hagel, J.; Qualls, J. S.; Brooks, J. S.; Balthes, E. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

In-plane magneto-photoluminescence studies of modulation-doped GaAs/AlGaAs coupled double quantum wells

Description: In-plane magnetic field photoluminescence spectra from n series of n-type modulation doped GaAs/Al{sub 0.3}Ga{sub 0.7}As coupled double quantum wells show distinctive doublet structures related to the tunnel-split ground sub-level states. The magnetic field behavior of the upper transition from the antisymmetric state strongly depends on sample mobility. In a lower mobility sample, the transition energy displays an N-type kink with field (namely a maximum followed by a minimum), whereas higher … more
Date: May 11, 2000
Creator: KIM,YONGMIN; PERRY,C.H.; SIMMONS,JERRY A. & KLEM,JOHN F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Photochemical arrays formed by spatial compartmentalization of colloidal nanoparticles in a polymer-based hydrogel

Description: The development of practical strategies for the assembly of semiconductor and metal colloid nanoparticles into ordered architectures is an area of considerable current interest, since it offers an opportunity for exploiting the optical and electronic properties of these colloids for device development. Prior research has explored creating such organized nanoparticle assemblies by Langmuir-Blodgett techniques or controlled solvent evaporation on suitable substrates. These approaches suffer from … more
Date: January 13, 2000
Creator: Firestone, M. A.; Rajh, T.; Makarova, O. V.; Seifert, S.; Tiede, D. M. & Thurnauer, M. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Anisotropies in magnetic field evolution and local Lyapunov exponents

Description: The natural occurrence of small scale structures and the extreme anisotropy in the evolution of a magnetic field embedded in a conducting flow is interpreted in terms of the properties of the local Lyapunov exponents along the various local characteristic (un)stable directions for the Lagrangian flow trajectories. The local Lyapunov exponents and the characteristic directions are functions of Lagrangian coordinates and time, which are completely determined once the flow field is specified. The … more
Date: January 13, 2000
Creator: Tang, X. Z. & Boozer, A. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

The importance of the toroidal magnetic field for the feasibility of a tokamak burning plasma experiment

Description: The next step in the demonstration of the scientific feasibility of a tokamak fusion reactor is a DT burning plasma experiment for the study and control of self-heated plasmas. In this paper, the authors examine the role of the toroidal magnetic field on the confinement of a tokamak plasma in the ELMy H-mode regime--the operational regime foreseen for ITER.
Date: March 22, 2000
Creator: Mazzucato, E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Crossing behavior of the singlet and triplet State of the negatively charged magneto-exciton in a GaAs/AlGaAs quantum well

Description: Polarized magneto-photoluminescence (MPL) measurements on a high mobility {delta}-doped GaAs/AlGaAs single quantum well from 0--60 T at temperatures between 0.37--2.1 K are reported. In addition to the neutral heavy hole magneto-exciton (X{sup 0}), the singlet (X {sub s}{sup {minus}}) and triplet (X {sub t}{sup {minus}}) states of the negatively charged magneto-exciton are observed in both polarizations. The energy dispersive and time-resolved MPL data suggest that their development is fundamen… more
Date: January 27, 2000
Creator: Munteanu, F. M.; Kim, Yongmin; Perry, C. H.; Rickel, D. G.; SImmons, Jerry A. & Reno, John L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Beam emittance calculation in the presence of an axially symmetric magnetic field

Description: The Fermilab electron cooling project requires low transverse electron velocities (both coherent and incoherent) in the solenoidal cooling section. One of the possible reasons for an increase of these velocities is aberrations introduced by optical elements in the axially symmetric portion of the beam channel (first of all, in the acceleration tube) preceding the cooling section. Most of these optical elements can be treated as thin lenses so that the aberrations can be characterized by an incr… more
Date: May 15, 2000
Creator: Shemyakin, Sergei Nagaitsev and Alexander
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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