Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Brigham Young University

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 7411 - 7440 of 8047

Full-Text Articles in Entire DC Network

Photoluminescence And Absorption Studies Of Defects In Cdte And Znxcd1-Xte Crystals, Cheryl Barnett Davis, David D. Allred, A. Reyes-Mena, Jesus González-Hernández, Ovidio González, Bret C. Hess, Worth P. Allred May 1993

Photoluminescence And Absorption Studies Of Defects In Cdte And Znxcd1-Xte Crystals, Cheryl Barnett Davis, David D. Allred, A. Reyes-Mena, Jesus González-Hernández, Ovidio González, Bret C. Hess, Worth P. Allred

Faculty Publications

We have studied at cryogenic temperatures photoluminescence features which lie more than 0.15 eV below the band edge in ZnxCd1-xTe (0≤x≤0.09) crystals. The same features, namely a defect band which lies at about 0.13-0.20 eV below the band-gap energy and a peak at 1.1 eV, that are observed in pure CdTe samples are observed in these alloy materials. In annealed samples we observe that the 1.1 eV feature, which has been attributed to tellurium vacancies, increases with fast cooling. Increased concentrations of tellurium vacancies can be understood in terms of the phase diagram of CdTe which indicates that higher concentrations …

Go to article

Another Cautionary Note On Interpreting Regression Results In Family Research: A Comment On Peterson And Gerson (1992), Alan J. Hawkins, Joseph A. Olsen, Richard R. Peterson, Kathleen Gerson May 1993

Another Cautionary Note On Interpreting Regression Results In Family Research: A Comment On Peterson And Gerson (1992), Alan J. Hawkins, Joseph A. Olsen, Richard R. Peterson, Kathleen Gerson

Faculty Publications

Occasionally in the family literature we receive reminders to be cautious about our interpretations of regressions results (e.g., Glenn & Kramer, 1985; Glenn & Shelton, 1983). After all, regression results are stated in the language of mathematics. We must be careful when we translate from the language of mathematics, which is blind to the human situation being represented by the numbers, into language that is meaningful in the human context. This brief not critiques the interpretation of regression results in an article by Peterson and Gerson (1992) that appeared in a recent issue of the Journal of Marriage and the …

Go to article

The Development Of An English-Influenced, Universal, Techno-Academic Rhetoric, Bill Eggington Apr 1993

The Development Of An English-Influenced, Universal, Techno-Academic Rhetoric, Bill Eggington

Deseret Language and Linguistic Society Symposium

No abstract provided.

Go to article

Microbial Spatial Heterogeneity In Microbiotic Crusts In Colorado National Monument. I. Algae, Anne E. Grondin, Jeffrey R. Johansen Apr 1993

Microbial Spatial Heterogeneity In Microbiotic Crusts In Colorado National Monument. I. Algae, Anne E. Grondin, Jeffrey R. Johansen

Great Basin Naturalist

Spatial heterogeneity in visually similar sites under Utah juniper canopy in Colorado National Monument was examined. Sample sites were arranged in a transect 24 m long, such that distances between samples were 0.013 m, 0.03 m, 1.0 m, 12 m, and 24 m. Twenty-five taxa of algae were observed, mostly belonging to Cyanophyta. Algal density varied by more than an order of magnitude within the 46 samples examined. The coefficients of variation for each distance class were very similar, demonstrating that algal patchiness can be as significant on a scale less than 0.013 m as it is on a scale …

Go to article

Language Transactions In Covenant And Contract, Chauncey Cazier Riddle Apr 1993

Language Transactions In Covenant And Contract, Chauncey Cazier Riddle

Deseret Language and Linguistic Society Symposium

No abstract provided.

Go to article

The Camel And Its Role In Shaping Mideastern Nomad Societies, Ralph W. Brauer Apr 1993

The Camel And Its Role In Shaping Mideastern Nomad Societies, Ralph W. Brauer

Comparative Civilizations Review

No abstract provided.

Go to article

Low-Frequency Feature In The First-Order Raman Spectrum Of Amorphous Carbon, David D. Allred, Qi Wang, Jesus González-Hernández Mar 1993

Low-Frequency Feature In The First-Order Raman Spectrum Of Amorphous Carbon, David D. Allred, Qi Wang, Jesus González-Hernández

Faculty Publications

In the first-order Raman spectrum of amorphous carbon (a-C) there is a low-frequency feature in the 200-900-cm-1 region. This feature is characteristic of the highly disordered amorphous-carbon materials. We note that the intensity of this feature is very sensitive to the thermal history of samples, thus suggesting that it is an important measure of the degree of disorder of the a-C materials. We also discuss the relationship between this feature and the phonon density of states of graphite.

Go to article

Exponential Growth Of An Unstable L=1 Diocotron Mode For A Hollow Electron Column In A Warm-Fluid Model, S. Neil Rasband, Ross L. Spencer, Richard R. Vanfleet Mar 1993

Exponential Growth Of An Unstable L=1 Diocotron Mode For A Hollow Electron Column In A Warm-Fluid Model, S. Neil Rasband, Ross L. Spencer, Richard R. Vanfleet

Faculty Publications

Numerical investigations of a warm-fluid model with an isothermal equation of state for the perpendicular dynamics of an axisymmetric, magnetically confined pure electron plasma predict an exponentially unstable, l=1, diocotron mode for hollow density profiles. The unstable mode can be identified with a stable, nonsmooth mode that exists in cold drift models but which is destabilized by finite temperature effects. The unstable mode has many properties similar to the experimental results reported by Driscoll [Phys. Rev. Lett. 64, 645 (1990)].

Go to article

Precision Spectroscopy Using The Lamb Dip In A Pure Ion Plasma, P. N. Barnes, Grant W. Hart Feb 1993

Precision Spectroscopy Using The Lamb Dip In A Pure Ion Plasma, P. N. Barnes, Grant W. Hart

Faculty Publications

The use of the Lamb dip as a technique for precision spectroscopy in a non-neutral plasma is explored through computer modeling. Using singly ionized magnesium as the ion and under typical pure ion plasma conditions, the measurement appears to be feasible. Under the conditions calculated here, the Lamb dip is only 4% wider than the natural linewidth of the transition.

Go to article

Ti-Ii Transition Probabilities And Radiative Lifetimes In Ti+ And The Solar Titanium Abundance, A. Bizzarri, M.C.E. Huber, A. Noels, N. Grevesse, Scott D. Bergeson, P. Tsekeris, J. E. Lawler Jan 1993

Ti-Ii Transition Probabilities And Radiative Lifetimes In Ti+ And The Solar Titanium Abundance, A. Bizzarri, M.C.E. Huber, A. Noels, N. Grevesse, Scott D. Bergeson, P. Tsekeris, J. E. Lawler

Faculty Publications

Transition probabilities of 100 Ti-II emission lines, originating from 7 different atomic levels, have been determined by combining branching fractions with radiative lifetimes. The branching fractions were meaures using Fourier transform spectroscopy on a hollow cathode. The radiative lifetimes of these 7 – and 35 additional – levels were measured using time resolved laser-induced fluorescence on a slow Ti ion beam. The transition probabilities of 21 very weak lines have been used to derive a solar titanium abundance of aTi=log(NTi/NH)+12=5.04±0.04 dex, which is insensitive to the solar model. This value is in …

Go to article

Oscillator Strengths Of The Si Ii 181 Nanometer Resonance Multiplet, Scott D. Bergeson, J. E. Lawler Jan 1993

Oscillator Strengths Of The Si Ii 181 Nanometer Resonance Multiplet, Scott D. Bergeson, J. E. Lawler

Faculty Publications

We report Si II experimental log (gf)-values of –2.38(4) for the 180.801 nm line, of –2.18(4) for the 181.693 nm line, and of –3.29(5) for the 181.745 nm line, where the number in parenthesis is the uncertainty in the last digit. The overall uncertainties (~10%) include the 1 σ random uncertainty (~6%) and an estimate of the systematic uncertainty. The oscillator strengths are determined by combining branching fractions and radiative lifetimes. The branching fractions are measured using standard spectroradiometry on an optically thin source; the radiative lifetimes are measured using time-resolved laser-induced fluorescence.

Go to article

Transition Probabilities For The 3s23p(2PO)–3s3p2(4P) Intersystem Lines Of Si Ii, Anthony G. Calamai, Peter L. Smith, Scott D. Bergeson Jan 1993

Transition Probabilities For The 3s23p(2PO)–3s3p2(4P) Intersystem Lines Of Si Ii, Anthony G. Calamai, Peter L. Smith, Scott D. Bergeson

Faculty Publications

Intensity ratios of lines of the spin-changing "intersystem" multiplet of Si II (4P → 2Po) at 234 nm have been used to determine electron densities and temperatures in a variety of astrophysical environments. However, the accuracy of these diagnostic calculations have been limited by uncertainties associated with the available atomic data. We report the first laboratory measurement, using an ion-trapping technique, of the radiative lifetimes of the three metastable levels of the 3s3p2 4P term of Si II. Our results are 104 ± 16, 406 ± 33, and 811 ± 77 µs for …

Go to article

Radiative Lifetimes, Branching Ratios, And Absolute Transition Probabilities In Cr Ii And Zn Ii, Scott D. Bergeson, J. E. Lawler Jan 1993

Radiative Lifetimes, Branching Ratios, And Absolute Transition Probabilities In Cr Ii And Zn Ii, Scott D. Bergeson, J. E. Lawler

Faculty Publications

New absolute atomic transition probability measurements are reported for 12 transitions in Cr II and two transitions in Zn II. These transition probabilities are determined by combining branching ratios measured by classical techniques and radiative lifetimes measured by time-resolved laser-induced fluorescence. The measurements are compared with branching fractions, radiative lifetimes, and transition probabilities in the literature. The 206 nm resonance multiplets in Cr II and Zn II are included in this work. These multiplets are very useful in determining the distribution of the elements in the gas versus grain phases in the interstellar medium.

Go to article

Linear Theory Of Non-Neutral Plasma Equilibrium In A Tilted Magnetic Field, Ross L. Spencer, Grant W. Hart Nov 1992

Linear Theory Of Non-Neutral Plasma Equilibrium In A Tilted Magnetic Field, Ross L. Spencer, Grant W. Hart

Faculty Publications

A linear perturbation expansion has been found that allows the rapid and accurate calculation of the response of a non-neutral plasma to a tilted magnetic field. The results of the calculation have been found to agree with previous three-dimensional equilibrium calculations, and also to agree with Keinigs' [Phys. Fluids 24, 860 (1981)] calculation of zero-frequency resonances caused by magnetic field errors. This expansion also allows the perturbed velocity to be calculated. It is speculated that this perturbed flow may be related to the enhanced radial transport in a non-neutral plasma with a tilted magnetic field.

Go to article

Use Of Raman Spectroscopy In Characterizing Soft X-Ray Multilayers: Tools In Understanding Structure And Interfaces, Ming Cai, Qi Wang, David D. Allred, Larry V. Knight, Dorian M. Hatch, A. Reyes-Mena, Guizhong Zhang Oct 1992

Use Of Raman Spectroscopy In Characterizing Soft X-Ray Multilayers: Tools In Understanding Structure And Interfaces, Ming Cai, Qi Wang, David D. Allred, Larry V. Knight, Dorian M. Hatch, A. Reyes-Mena, Guizhong Zhang

Faculty Publications

Our group is studying the structure and interfaces of soft x-ray multilayers by various techniques including x-ray diffraction and Raman spectroscopy. Raman spectroscopy is particularly useful since it is sensitive to the identity of individual bonds and thus can potentially characterize the abruptness of interfaces in multilayers. Blocking interfacial mixing is very important in achieving and maintaining high reflectivity. We report our studies of the as-deposited and postannealed structure of Mo/Si and W/C multilayers. The Mo/Si system is probably the most widely studied multilayer currently because of its potential applications for soft x-ray projection lithography for the range of 13 …

Go to article

Publications, C. F. Lee, Frank Joseph Shulman, Tai-Loi Ma, Edward Martinique, Maureen H. Donovan Oct 1992

Publications, C. F. Lee, Frank Joseph Shulman, Tai-Loi Ma, Edward Martinique, Maureen H. Donovan

Journal of East Asian Libraries

No abstract provided.

Go to article

On The Eighteenth-Century English Misreading Of The Chinese Garden, Liangyan Ge Oct 1992

On The Eighteenth-Century English Misreading Of The Chinese Garden, Liangyan Ge

Comparative Civilizations Review

No abstract provided.

Go to article

Comparative Logics And The Comparative Study Of Civilizations, Walter Benesch Oct 1992

Comparative Logics And The Comparative Study Of Civilizations, Walter Benesch

Comparative Civilizations Review

No abstract provided.

Go to article

The Mormon Concept Of God: A Philosophical Analysis By Francis J. Beckwith And Stephen E. Parrish, James E. Faulconer Oct 1992

The Mormon Concept Of God: A Philosophical Analysis By Francis J. Beckwith And Stephen E. Parrish, James E. Faulconer

BYU Studies

No abstract provided.

Go to article

Adaptive Boundary Detection Using “Live-Wire” Two-Dimensional Dynamic Programming, William A. Barrett, Bryan S. Morse, Eric N. Mortensen, Jayaram Udupa Oct 1992

Adaptive Boundary Detection Using “Live-Wire” Two-Dimensional Dynamic Programming, William A. Barrett, Bryan S. Morse, Eric N. Mortensen, Jayaram Udupa

Faculty Publications

An adaptive boundary detection algorithm that uses two-dimensional dynamic programming is presented. The algorithm is less constrained than previous one-dimensional dynamic programming algorithms and allows the user to interactively determine the mathematically optimal boundary between a user-selected seed point and any other dynamically selected "free” point in the image. Interactive movement of the free point by the cursor causes the boundary to behave like a “live wire” as it adapts to the new minimum cost path between the seed point and the currently selected free point. The algorithm can also be adapted or customized to learn boundary-defining features for a …

Go to article

Diatom Flora Of Beaver Dam Creek, Washington County, Utah, Usa, Kurtis H. Yearsley, Samuel R. Rushforth, Jeffrey R. Johansen Sep 1992

Diatom Flora Of Beaver Dam Creek, Washington County, Utah, Usa, Kurtis H. Yearsley, Samuel R. Rushforth, Jeffrey R. Johansen

Great Basin Naturalist

The diatom flora of Beaver Dam Creek, Washington County, Utah, was studied. The study area is in a warm Mojave Desert environment at an elevation between 810 and 850 m. A total of 99 taxa were identified from composite samples taken in the fall, winter, spring, and summer seasons. These taxa are all broadly distributed and no endemic species were encountered. Three new records for the state of Utah were identified: Gomphoneis eriense Skv. & Mayer, Navicula elginensis var. lata. (M. Perag.) Patr., and Nitzschia calida Grun. The most important taxa throughout the study as determined by multiplying percent presence …

Go to article

Approximation By Interval Bezier Curves, Thomas W. Sederberg, Rida T. Farouki Sep 1992

Approximation By Interval Bezier Curves, Thomas W. Sederberg, Rida T. Farouki

Faculty Publications

The interval Bezier curve, which, unlike other curve and surface approximation schemes, can transfer a complete description of approximation errors between diverse CAD/CAM systems that impose fundamentally incompatible constraints on their canonical representation schemes, is described. Interval arithmetic, which offers an essentially infallible way to monitor error propagation in numerical algorithms that use floating-point arithmetic is reviewed. Affine maps, the computations of which are key operations in the de Casteljau subdivision and degree-elevation algorithms for Bezier curves, the floating-point error propagation in such computations, approximation by interval polynomials, and approximation by interval Bezier curves are discussed.

Go to article

Species Of The Cretaceous Tree Fern Tempskya From Utah, William D. Tidwell, Naomi Hebbert Sep 1992

Species Of The Cretaceous Tree Fern Tempskya From Utah, William D. Tidwell, Naomi Hebbert

Faculty Publications

Nine species of the permineralized stems of Tempskya were investigated from the Lower Cretaceous Cedar Mountain and Burro Canyon Formations, and the lower Upper Cretaceous Dakota Formation in central and southeastern Utah. Tempskya jonesii, T. stichkae, and T. readii are new and are differentiated on the basis of the radial orientation of their dorsiventral stems, their internodal lengths, the lack of sclerenchyma in the inner cortex of T. jonesii, the three nearly continuous zones of sclerenchyma in the inner cortex off T. stichkae, and the completely sclerotic inner cortex of T. readii. Specimens of T. jonesii and T. minor were …

Go to article

Interface Cavitation Damage In Polycrystalline Copper, Brent L. Adams, David P. Field Jun 1992

Interface Cavitation Damage In Polycrystalline Copper, Brent L. Adams, David P. Field

Faculty Publications

The authors acknowledge the support of the Office of Basic Energy Sciences of the United States Department of Energy. Determination of an interface damage function (IDF) from a stereological procedure similar to that presented by Hilliard is described. The mathematical and experimental simplicity of the method is utilized in measuring an IDF for polycrystalline copper crept at 0.6T sub m under uniaxial tension. Whereas previous work focused on a five parameter description of the local state of a grain boundary, the domain of the IDF is increased to eight degrees of freedom in the present study to include the complete …

Go to article

A General Three Dimensional All Quadrilateral Surface Mesh Generation Algorithm, Roger Cass Apr 1992

A General Three Dimensional All Quadrilateral Surface Mesh Generation Algorithm, Roger Cass

Theses and Dissertations

Among the available all-quadrilateral mesh generation algorithms progressive-front offers the best quality and robustness. The paving algorithm is a progressive-front technique that generates a two dimensional mesh of all quadrilaterals on planar surfaces. The technique is particularly suited to meshing irregular boundaries with interior holes. This thesis presents an extension of the paving algorithm to generalized three dimensional surfaces. The major problems in three-dimensional surface mesh generation are projection of nodes, calculation of interior angles, and connection of mesh fronts. The solutions to these problems are presented. This work is part of the ongoing CUBIT project at Sandia Labs. The …

Go to article

Geography In The Medieval Muslim World: Seeking A Basis For Comparison Of The Development Of The Natural Sciences In Different Cultures, Ralph W. Brauer Apr 1992

Geography In The Medieval Muslim World: Seeking A Basis For Comparison Of The Development Of The Natural Sciences In Different Cultures, Ralph W. Brauer

Comparative Civilizations Review

No abstract provided.

Go to article

Civilization: A Definition Part Ii. The Nature Of Formal Knowledge Systems, John K. Hord Apr 1992

Civilization: A Definition Part Ii. The Nature Of Formal Knowledge Systems, John K. Hord

Comparative Civilizations Review

No abstract provided.

Go to article

Pressure Dependence Of The Thermal Conductivity Of Pyrophyllite To 40 Kbar, Wei Chen, Daniel L. Decker Mar 1992

Pressure Dependence Of The Thermal Conductivity Of Pyrophyllite To 40 Kbar, Wei Chen, Daniel L. Decker

Faculty Publications

A mathematical model for calculating the temperature distribution as a function of power delivered to a line source and the thermal conductivity of the surrounding medium in the pressure cell of a cubic-anvil press was derived. The model will handle anisotropic thermal conductivities. A simple sample assembly consisting of a line source and two or three thermocouple junctions is described. A comparison of measured to calculated temperatures yields the thermal conductivity. Thermal conductivity measurements were made on natural pyrophyllite and baked pyrophyllite to 40 kbar. For the natural pyrophyllite the thermal conductivity parallel to the bedding plane at room temperature …

Go to article

Amy Brown Lyman And Social Service Work In The Relief Society, David Roy Hall Jan 1992

Amy Brown Lyman And Social Service Work In The Relief Society, David Roy Hall

Theses and Dissertations

This thesis examines the life and accomplishments of Amy Brown Lyman, particularly as they relate to charity activities and social service work of the Relief Society of the Church of Jesus Christ of Latter-day Saints. It considers her early life, her call to the General Board in 1909, her contributions to the creation of the Relief Society Social Services Department in 1919, her association with national and international leaders of reform, and her efforts in sponsoring and supporting social welfare legislation in Utah. Also examined are her work with the Social Services Department during the Great Depression, her mission to …

Go to article

X-Ray Diode Using A Silicon Field Emission Photocathode, W. I. Karian, Larry V. Knight, David D. Allred, A. Reyes-Mena Jan 1992

X-Ray Diode Using A Silicon Field Emission Photocathode, W. I. Karian, Larry V. Knight, David D. Allred, A. Reyes-Mena

Faculty Publications

We have produced arrays of 10,000 sharp p-type silicon points using an etch plus oxidation method. The points were used as electron emitters. No high vacuum cesiation or high temperature cleaning was needed to observe the electron emission. These are seen to be photosensitive sources of electrons at 200 K and 300 K. They were also used to produce AlKα x-rays. This constitutes the first use of etched, point arrays for generating electrons for x-ray sources.

Go to article

First Prev Next Last