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First Gps Baseline Results From The North Andes, James N. Kellogg, Jeffrey T. Freymueller, Timothy H. Dixon, Ruth E. Neilan, Clemente Ropain U., Sergio Camargo M., Benjamin Fernandez Ch., James L. Stowell, Anibal Salazar, Jaime Mora V., Luis Espin, Vernon Perdue, Leonard Leos Mar 1990

First Gps Baseline Results From The North Andes, James N. Kellogg, Jeffrey T. Freymueller, Timothy H. Dixon, Ruth E. Neilan, Clemente Ropain U., Sergio Camargo M., Benjamin Fernandez Ch., James L. Stowell, Anibal Salazar, Jaime Mora V., Luis Espin, Vernon Perdue, Leonard Leos

Faculty Publications

The CASA UNO GPS (Global Positioning System) experiment (January-February 1988) has provided the first epoch baseline measurements for the study of plate motions and crustal deformation in and around the North Andes. Two dimensional horizontal baseline repeatabilities are as good as 5 parts in 108 for short baselines (100-1000km), and better than3 parts in 108 for long baselines (>1000km). Vertical repeatabilities are typically 4 -6 cm, with a weak dependence on baseline length. The expected rate of plate convergence across the Colombia Trench is 6-8 cm/yr, which should be detectable by the repeat experiment planned for 1991. …

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Photoluminescence Studies In Znxcd1-Xte Single Crystals, David D. Allred, Jesus González-Hernández, Elías López-Cruz, Worth P. Allred Mar 1990

Photoluminescence Studies In Znxcd1-Xte Single Crystals, David D. Allred, Jesus González-Hernández, Elías López-Cruz, Worth P. Allred

Faculty Publications

The crystalline quality of ZnxCd1-xTe single crystals prepared by a modified Bridgman method with 0≤x≤0.05 has been analyzed using photoluminescence. The spectrum of a typical sample is dominated by lines originating from the recombination of free and bound excitons. Lines due to free excitons in their ground and first excited states are observed in both the pure CdTe and the mixed crystals. Excitons bound to Dc vacancies are observed in the pure CdTe crystal but not in the mixed crystal. Weaker and broader features appearing at energies below the exciton emission range were associated with transitions involving free-to-bound and bound-to-bound …

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On Two Function-Spaces Which Are Similar To L0, S J. Dilworth, D A. Trautman Feb 1990

On Two Function-Spaces Which Are Similar To L0, S J. Dilworth, D A. Trautman

Faculty Publications

No abstract provided.

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Inhomogeneous Broadening In Spectral Bands Of Carbonmonoxymyoglobin: The Connection Between Spectral And Functional Heterogeneity, Todd B. Sauke, P. Ormos, A. Ansari, D. Braunstein, B. R. Cowen, H. Fraunfelder, M. K. Hong, I. E. T. Iben, P. J. Steinbach, R. D. Young Jan 1990

Inhomogeneous Broadening In Spectral Bands Of Carbonmonoxymyoglobin: The Connection Between Spectral And Functional Heterogeneity, Todd B. Sauke, P. Ormos, A. Ansari, D. Braunstein, B. R. Cowen, H. Fraunfelder, M. K. Hong, I. E. T. Iben, P. J. Steinbach, R. D. Young

Faculty Publications

The rebinding kinetics of CO to myoglobin after flash photolysis is nonexponential in time below approximately 180 K; the kinetics is governed by a distribution of enthalpic barriers. This distribution results from inhomogeneities in the protein conformation, referred to as conformational substates. Hole-burning experiments on the Soret and IR CO-stretch bands test the assumption that an inhomogeneous distribution of conformational substates results in inhomogeneously broadened spectra. CO was slowly photolyzed at different wavelengths in the Soret band at 10 K. Both the Soret band and the CO-stretch band A1, centered at 1,945 cm-1, shift during photolysis, demonstrating that different wavelengths …

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Utility Function And Fiscal Illusion From Grants, Yeung-Nan Shieh, J. P. O'Brien Jan 1990

Utility Function And Fiscal Illusion From Grants, Yeung-Nan Shieh, J. P. O'Brien

Faculty Publications

No abstract provided.

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A Course In Laboratory And Stockroom Management, John T. Moore Jan 1990

A Course In Laboratory And Stockroom Management, John T. Moore

Faculty Publications

No abstract provided.

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Lévy Laplacian Of Generalized Functions On A Nuclear Space, Hui Hsiung Kuo, Nobuaki Obata, Kimiaki Saitô Jan 1990

Lévy Laplacian Of Generalized Functions On A Nuclear Space, Hui Hsiung Kuo, Nobuaki Obata, Kimiaki Saitô

Faculty Publications

The Lévy Laplacian ΔF(ξ) = limN→∞N-1∑n = 1N 〈F″(ξ),en⊗ en〉 is shown to be equal to (i) ∝TF″s″(ξ;t)dt, where Fs″ is the singular part of F″, and (ii) 2limρ{variant}→0ρ{variant}-2(MF(ξ,ρ{variant})-F(ξ)), where MF is the spherical mean of F. It is proved that regular polynomials are Δ-harmonic and possess the mean value property. A relation between the Lévy Laplacian Δ and the Gross Laplacian ΔGF(ξ) = ∑n = 1∞=〈F″(ξ),en⊗ en〉 is obtained. An application to white noise calculus is discussed. © 1990.

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Local Semigroups In Lie Groups And Locally Reachable Sets, Karl H. Hofmann, Jimmie D. Lawson Jan 1990

Local Semigroups In Lie Groups And Locally Reachable Sets, Karl H. Hofmann, Jimmie D. Lawson

Faculty Publications

In this paper the relationship between locally reachable sets for a fixed set of controls in the Lie algebra of a Lie group and the local semigroups generated by the corresponding one-parameter semigroup is considered. It is convenient to carry out the investigation in the Lie algebra itself, and the appropriate machinery for doing this is first developed. It is shown that local semigroups contain locally reachable sets. A general criterion (rerouting) is developed for the converse inclusion, and it is shown that if the set of controls is contained in a proper cone or is a Lie wedge (i.e., …

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A Characterization Of A Class Of Non-Binary Matroids, James G. Oxley Jan 1990

A Characterization Of A Class Of Non-Binary Matroids, James G. Oxley

Faculty Publications

A well-known result of Tutte is that U2,4, the 4-point line, is the only non-binary matroid M such that, for every element e, both Mβe and M e, the deletion and contraction of e from M, are binary. This paper characterizes those non-binary matroids M such that, for every element e, Mβe or M e is binary. © 1990.

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Characterization Of Metal/Carbon Multilayers By Raman Spectroscopy, David D. Allred, Qi Wang, Jesus González-Hernández Jan 1990

Characterization Of Metal/Carbon Multilayers By Raman Spectroscopy, David D. Allred, Qi Wang, Jesus González-Hernández

Faculty Publications

Laser Raman spectroscopy has been found to be useful for characterizing amorphous semiconductor multilayers, especially the interfaces of multilayers. Recently, we have extended this technique to the characterization of magnetron sputtered multilayers commonly used as reflectors in soft x-ray optics. Unlike the multilayers previously studied which contained only semiconductors and dielectrics, these are generally semiconductor/metal multilayers. We report here on the Raman characterization of the most common class of multilayers used in soft x-ray optics, those that contain a high density metal like tungsten interspersed with layers of carbon. In all of the metal/carbon multilayers the dominate feature in the …

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Design Of High Performance Soft X-Ray Windows, Raymond T. Perkins, David D. Allred, Larry V. Knight, James M. Thorne Jan 1990

Design Of High Performance Soft X-Ray Windows, Raymond T. Perkins, David D. Allred, Larry V. Knight, James M. Thorne

Faculty Publications

X-ray windows are used in sources and detectors to separate the neighborhood of the x-ray generation or detection from the use environment. While each use has its own requirements, there are some principles that should be used in designing an optimal x-ray window. Because x-rays are absorbed to some extent by all materials, minimizing absorption is one criterion in preparing windows. Also, for most uses there is a pressure difference across the window so that ensuring pinhole-free structure and sufficient mechanical strength to support the differential is another criterion for window design. Traditionally, absorption is minimized by fabricating the window …

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Rheology Of Aqueous Suspensions Of Polystyrene Latex Stabilized By Grafted Poly(Ethylene Oxide), Harry J. Ploehn, J. W. Goodwin Jan 1990

Rheology Of Aqueous Suspensions Of Polystyrene Latex Stabilized By Grafted Poly(Ethylene Oxide), Harry J. Ploehn, J. W. Goodwin

Faculty Publications

A water-soluble carbodiimide has been used to end-graft aminated poly (ethylene oxide)(PEO) chemically onto colloidal polystyrene particles. Two particle sizes (115 and 347 nm diameter) and two PEO molecular weights (112 000 and 615 000 g mol–1) were combined to give suspensions with four different ratios of polymer layer thickness to particle radius. Electrophoresis demonstrated that the PEO was grafted, not just adsorbed. Dynamic light scattering showed that the adsorbed and grafted layers had similar structures and that non-ionic surfactant perturbed the PEO configurations. Steady shear and oscillatory rheometry indicated that long-ranged polymeric forces between particles governed the …

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Mathematical Modeling Of An H2s Removal Electrolyzer, Z. Mao, P. Adanuvor, Ralph E. White Jan 1990

Mathematical Modeling Of An H2s Removal Electrolyzer, Z. Mao, P. Adanuvor, Ralph E. White

Faculty Publications

A mathematical model is presented for a high temperature H2S electrolyzer. It is shown that the maximum current in this type of a cell is determined entirely by the transport rate of sulfide ions through the separator. It is suggested that this model could be used to determine the feasibility of various designs for this electrolyzer.

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A Computer Simulation Of The Oxygen Reduction Reaction In Carbonate Melts, P. K. Adanuvor, Ralph E. White, A. J. Appleby Jan 1990

A Computer Simulation Of The Oxygen Reduction Reaction In Carbonate Melts, P. K. Adanuvor, Ralph E. White, A. J. Appleby

Faculty Publications

A computer simulation of the oxygen reduction reaction in various carbonate melts has been carried out under steady-state conditions on the basis of a proposed kinetic model which takes into consideration the autocatalytic reaction involving oxygen and other reducible oxygen species in the melt, and the neutralization of oxide ions by dissolved carbon dioxide. A simulation of the presence of (physically) dissolved oxygen, in the diffusion layer region of the melt, corresponding to the possible situation in porous electrodes, causes a significant enhancement in the polarization curves, particularly in the mass-transfer control region. On the other hand, high levels of …

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Estimation Of The Diffusion Coefficient And Solubility For A Gas Diffusing Through A Membrane, Michael C. Kimble, Ralph E. White, Yu-Min Tsou, R. Neal Beaver Jan 1990

Estimation Of The Diffusion Coefficient And Solubility For A Gas Diffusing Through A Membrane, Michael C. Kimble, Ralph E. White, Yu-Min Tsou, R. Neal Beaver

Faculty Publications

Analysis of the data obtained by the electrochemical monitoring technique for diffusion of a gas through a membrane is considered. It is shown that combining a numerical method with a nonlinear parameter estimation technique provides a means to determine values for the diffusion coefficient and the solubility of the diffusing gas. It is shown that better accuracy can be obtained for the diffusion coefficient and solubility of this gas by using the method presented and all experimental data rather than only part of the data, as has often been done in the past.

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Mathematical Model Of A Lithium/Polypyrrole Cell, Taewhan Yeu, Ralph E. White Jan 1990

Mathematical Model Of A Lithium/Polypyrrole Cell, Taewhan Yeu, Ralph E. White

Faculty Publications

A mathematical model to simulate the charge/discharge behavior of a lithium/lithium perchlorate-propylene carbonate/polypyrrole(Li/LiClO4-PC/PPy) secondary battery cell is presented. The model can be used to gain a better understanding of the behavior of this cell and to provide guidance toward the design of new secondary batteries which utilize an electronically conductive polymer such as polypyrrole (PPy) as the cathode. The model includes the capability of handling charge and discharge behavior and is used to study the effect of various design parameters on the performance of the cell.

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The Effects Of Separator Design On The Discharge Performance Of A Starved Lead-Acid Cell, T. V. Nguyen, Ralph E. White, Hiram Gu Jan 1990

The Effects Of Separator Design On The Discharge Performance Of A Starved Lead-Acid Cell, T. V. Nguyen, Ralph E. White, Hiram Gu

Faculty Publications

A mathematical model of a starved lead-acid cell has been developed to study the dynamic behavior of the cell during discharge. Concentrated binary electrolyte theory and a volume-averaging technique were used to model the transport of electrolyte. The model can be used to predict cell voltage and profile of: acid concentration, overpotential, porosity, reaction rate, and electrode capacity, as functions of time. The effects of separator thickness and its porosity were examined with respect to cold-cranking amperage and reserve capacity of the battery. The separator was found to be a significant factor governing performance.

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Lottery Proceeds In California Pay For Installation Of A Ground-Water Monitoring System, June Ann Oberdorfer, J. W. Williams, M. G. Smelser Jan 1990

Lottery Proceeds In California Pay For Installation Of A Ground-Water Monitoring System, June Ann Oberdorfer, J. W. Williams, M. G. Smelser

Faculty Publications

No abstract provided.

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Advanced Infrared Optically Black Baffle Materials, David D. Allred, Ronald D. Seals, C. M. Egert Jan 1990

Advanced Infrared Optically Black Baffle Materials, David D. Allred, Ronald D. Seals, C. M. Egert

Faculty Publications

Infrared optically black baffle surfaces are an essential component of many advanced optical systems. All internal surfaces in advanced infrared optical sensors that require stray light management to achieve resolution are of primary concern in baffle design. Current industrial materials need improvements to meet advanced optical sensor systems requirements for optical, survivability, and endurability. Baffles are required to survive and operate in potentially severe environments. Robust diffuse-absorptive black surfaces, which are (1) thermally and mechanically stable to threats of x-ray, launch, and in-flight maneuver conditions, with specific densities to allow an acceptable weight load, (2) handleable during assembly, (3) cleanable, …

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Photoconductive Characterization Of Znxcd1-Xte (0≤X≤0.25) Single Crystal Alloys, David D. Allred, Elías López-Cruz, Jesus González-Hernández, Worth P. Allred Jan 1990

Photoconductive Characterization Of Znxcd1-Xte (0≤X≤0.25) Single Crystal Alloys, David D. Allred, Elías López-Cruz, Jesus González-Hernández, Worth P. Allred

Faculty Publications

Large grain polycrystalline and single crystals of ZnxCd1-xTe grown by a modified Bridgman method were studied using the photoluminescence and photoconductivity techniques. The temperature dependence of the band gap, as determined by photoluminescence, follows the Varshni equation for measuring temperature in the range of 15-290 K. One of the fitted parameters, the Debye temperature, monotonically decreases with the increase of the atomic zinc concentration. A close correlation between the photoluminescence and photoconductivity measurements is also found. Samples in which the photoluminescence spectra exhibit emission bands associated to cadmium vacancies and other structural defects, show a photoresponse curve which includes, in …

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Deposition Of Zinc Selenide By Atomic Layer Epitaxy For Multilayer X-Ray Optics, J.K. Shurtleff, David D. Allred, R. T. Perkins, J. M. Thorne Jan 1990

Deposition Of Zinc Selenide By Atomic Layer Epitaxy For Multilayer X-Ray Optics, J.K. Shurtleff, David D. Allred, R. T. Perkins, J. M. Thorne

Faculty Publications

Thin film deposition techniques currently being used to produce multilayer x-ray optics (MXOs) have difficulty producing smooth, uniform multilayers with d-spacings less than about twelve angstroms. We are investigating atomic layer epitaxy (ALE) as an alternative to these techniques. ALE is a chemical vapor deposition technique which deposits an atomic layer of material during each cycle of the deposition process. The thickness of a film deposited by ALE depends only on the number of cycles. Multilayers deposited by ALE should be smooth and uniform with precise d-spacings which makes ALE an excellent technique for producing multilayer x-ray optics. We have …

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Annealing Behavior Of The Photoluminescence Lines In Cdte And Znx Cd1-X Te Single Crystals, David D. Allred, A. Reyes-Mena, Jesus González-Hernández, Elías López-Cruz, Worth P. Allred Jan 1990

Annealing Behavior Of The Photoluminescence Lines In Cdte And Znx Cd1-X Te Single Crystals, David D. Allred, A. Reyes-Mena, Jesus González-Hernández, Elías López-Cruz, Worth P. Allred

Faculty Publications

The main lines in the photoluminescence spectra of Zn1Cd1-xTe single crystals grown by a modified Bridgman method in the compositional range of 0≤X≤0.25 have been identified. All crystals show only near-band-edge emission. To assist in the identification, various samples with different compositions were annealed under a Cd atmosphere. In the pure crystals, the prominent (A°, X) bound exciton line, as well as the doublet at longer wavelengths, disappear after the annealing. In contrast, the treatments do not change significantly the PL spectra of the mixed crystals.

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Diffuse Absorbing Beryllium Coatings Produced By Magnetron Sputtering, David D. Allred, C. M. Egert Jan 1990

Diffuse Absorbing Beryllium Coatings Produced By Magnetron Sputtering, David D. Allred, C. M. Egert

Faculty Publications

Beryllium coatings with varying thicknesses and columnar grain sizes were deposited by low temperature magnetron sputtering and wet chemically etched to enhance diffuse absorption of light. After etching these coatings exhibited a matte black surface finish and low specular reflectance (below 2%) in the IR up to a critical wavelength dependent upon the original grain size of the coating. Extremely thick coatings (350 µm) with original grain sizes of 10 to 12 µm were produced which exhibited specular reflectances below 0.5% up to 50 µm wavelength and a Lambertian BRDF at 10.6 µm averaging 4.3x10-3 ster-1. Scanning electron micrographs are …

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A Relaxation Algorithm For Segmentation Of The Endocardial Surface From Cine Ct, William A. Barrett, Bryan S. Morse Sep 1989

A Relaxation Algorithm For Segmentation Of The Endocardial Surface From Cine Ct, William A. Barrett, Bryan S. Morse

Faculty Publications

A relaxation algorithm has been developed for automated segmentation of the endocardial surface from contrast Cine CT images. The image is contoured at an initial density threshold and a one-dimensional edge operator is applied orthogonally to each point of the contour. Output from the operator is used to generate a histogram, the mode of which identifies a new threshold. The image is contoured again at the new threshold and the process is repeated. Iteration continues with successive threshold estimates converging to a stable value in the region of the endocardial surface. Computer-determined thresholds compare favorably with manual segmentation while reducing …

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Probabilistic Segmentation Of Myocardial Tissue By Deterministic Relaxation, William A. Barrett, Shawn C. Becker, Jerome A. Broekhuijsen Sep 1989

Probabilistic Segmentation Of Myocardial Tissue By Deterministic Relaxation, William A. Barrett, Shawn C. Becker, Jerome A. Broekhuijsen

Faculty Publications

A recently-developed probabilistic model for automatically segmenting regions of interest in abdominal CT scans has been adapted to the challenging task of segmenting myocardial tissue in Cine CT scans. A system has been implemented on relatively low-cost hardware which performs such segmentations. Special techniques have been developed to improve consistency and accuracy. Early results of testing this new modality are encouraging and promising. Based on observations from experimentation, new directions for future work have been identified.

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Interactive Measurement Of Three-Dimensional Cardiac Morphology, William A. Barrett, Shawn C. Becker Sep 1989

Interactive Measurement Of Three-Dimensional Cardiac Morphology, William A. Barrett, Shawn C. Becker

Faculty Publications

Techniques have been developed for extracting three-dimensional (3D) measurements directly and interactively from 3D representations of Cine CT images. In order to obtain 3D measurements the anatomical surface is interrogated directly through the use of a 3D graphical "probe" (line). The probe is interactively positioned and stretched between any visible surface points to allow direct capture of 3D (linear) distance. Distance measurements are updated in real time as the probe dynamically "penetrates" any intervening anatomy while providing valuable depth cuing for visual feedback and probe placement. Curvilinear distance is obtained by stretching the probe over multiple surface points. The probe …

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A Note On Roe's Characterization Of The Sine Function, Ralph Howard Mar 1989

A Note On Roe's Characterization Of The Sine Function, Ralph Howard

Faculty Publications

No abstract provided.

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Simultaneous Diagonalization Of Matrices Parametrized By A Projective Algebraic Curve, William A. Adkins Jan 1989

Simultaneous Diagonalization Of Matrices Parametrized By A Projective Algebraic Curve, William A. Adkins

Faculty Publications

If K is an algebraic function field in one variable over an algebraically closed field k, then conditions are presented to insure that a matrix A ∈ M (K) is diagonalizable by means of a similarity transformation T ∈ GL(n, k). This result generalizes results of Friedland [1] and Motzkin-Taussky [4]. © 1989. n

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A Note On Negami's Polynomial Invariants For Graphs, James G. Oxley Jan 1989

A Note On Negami's Polynomial Invariants For Graphs, James G. Oxley

Faculty Publications

Negami has introduced two polynomials for graphs and proved a number of properties of them. In this note, it is shown that these polynomials are intimately related to the well-known Tutte polynomial. This fact is used, together with a result of Brylawski, to answer a question of Negami. © 1989.

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The Regular Matroids With No 5-Wheel Minor, James G. Oxley Jan 1989

The Regular Matroids With No 5-Wheel Minor, James G. Oxley

Faculty Publications

For r in {3, 4}, the class of binary matroids with no minor isomorphic to M(Wr), the rank-r wheel, has an easily described structure. This paper determines all graphs with no W5-minor and uses this to show that the class of regular matroids with no M(W5)-minor also has a relatively simple structure. © 1989.

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