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

Physical Sciences and Mathematics Commons™

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

2003

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 391 - 420 of 3319

Full-Text Articles in Physical Sciences and Mathematics

Measurement Of The Mass Difference M(DS+)–M (D+) At Cdf Ii, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration Oct 2003

Measurement Of The Mass Difference M(DS+)–M (D+) At Cdf Ii, Darin Acosta, Kenneth A. Bloom, Collider Detector At Fermilab Collaboration

Kenneth Bloom Publications

We present a measurement of the mass difference m(Ds+)– m (D+), where both the Ds+ and D+ are reconstructed in the Φπ+ decay channel. This measurement uses 11.6 pb-1 of data collected by CDF II using the new displaced-track trigger. The mass difference is found to be m(Ds+)–m (D+)=99.41±0.38(stat)±0.21(syst) MeV/c2.

Go to article

Ordering Tendencies In Octahedral Mgo-Zno Alloys, Gus L. W. Hart, Mahdi Sanati, Alex Zunger Oct 2003

Ordering Tendencies In Octahedral Mgo-Zno Alloys, Gus L. W. Hart, Mahdi Sanati, Alex Zunger

Faculty Publications

Isostrutural II-VI alloys whose components are either rocksalt stable (e.g., CaO-MgO) or zincblende stable (e.g., ZnS-ZnSe) are known to be thermodynamically unstable at low temperatures, showing a miscibility gap and no bulk ordering. In contrast, we show that heterostructural MgO-ZnO is stable, under certain conditions, in the sixfold-coordinated structure for Zn concentrations below 67%, giving rise to spontaneously ordered alloys. Using first-principles calculations, we explain the origin of this stability, the structures of their low-temperature ordered phases, short-range-order patterns, and their optical band-gap properties.

Go to article

Sylvester: Ushering In The Modern Era Of Research On Odd Perfect Numbers, Steven Gimbel, John Jaroma Oct 2003

Sylvester: Ushering In The Modern Era Of Research On Odd Perfect Numbers, Steven Gimbel, John Jaroma

Philosophy Faculty Publications

In 1888, James Joseph Sylvester (1814-1897) published a series of papers that he hoped would pave the way for a general proof of the nonexistence of an odd perfect number (OPN). Seemingly unaware that more than fifty years earlier Benjamin Peirce had proved that an odd perfect number must have at least four distinct prime divisors, Sylvester began his fundamental assault on the problem by establishing the same result. Later that same year, he strengthened his conclusion to five. These findings would help to mark the beginning of the modern era of research on odd perfect numbers. Sylvester's bound stood …

Go to article

Electrochemical Preparation Of Chitosan/Hydroxyapatite Composite Coatings On Titanium Substrates, Jody G. Redepenning, Guhanand Venkataraman, Jun Chen, Nathan Stafford Oct 2003

Electrochemical Preparation Of Chitosan/Hydroxyapatite Composite Coatings On Titanium Substrates, Jody G. Redepenning, Guhanand Venkataraman, Jun Chen, Nathan Stafford

Jody Redepenning Publications

Composite coatings containing brushite (CaHPO4 • 2H2O) and chitosan were prepared by electrochemical deposition. The brushite/chitosan composites were converted to hydroxyapatite/chitosan composites in aqueous solutions of sodium hydroxide. The coatings ranged from 1 to 15% chitosan by weight. Qualitative assessment of the coatings showed adhesion signifi cantly improved over that observed for electrodeposited coatings of pure HA.

Go to article

Hygroscopic Growth Of Ammonium Sulfate/Dicarboxylic Acids, Matthew E. Wise, Jason D. Surratt, Daniel B. Curtis, John E. Shilling, Margaret A. Tolbert Oct 2003

Hygroscopic Growth Of Ammonium Sulfate/Dicarboxylic Acids, Matthew E. Wise, Jason D. Surratt, Daniel B. Curtis, John E. Shilling, Margaret A. Tolbert

CUP Faculty Research

Recent studies have shown that tropospheric sulfate aerosols commonly contain 50% by mass organic species. The influence of these organics on the chemical and physical properties of sulfate aerosols is not fully established. We have measured the water activity of pure dicarboxylic acids and eutonic mixtures of ammonium sulfate/dicarboxylic acids at 25°C and have calculated van't Hoff factors for each individual system. We have also used the vapor pressure data to determine the hygroscopic growth curves for pure dicarboxylic acids and eutonic mixtures and provide power law fits to the data. For the systems studied we find that the presence …

Go to article

Redox Scale For Assigning An Oxidizing/Reducing Potential To Groundwater: Method Development And Initial Results, Julie Bertoia, Vernon Hodge, Klaus J. Stetzenbach, Amy J. Smiecinski Oct 2003

Redox Scale For Assigning An Oxidizing/Reducing Potential To Groundwater: Method Development And Initial Results, Julie Bertoia, Vernon Hodge, Klaus J. Stetzenbach, Amy J. Smiecinski

Publications (YM)

This report outlines the progress on Task 33 of the Department of Energy's Yucca Mountain Cooperative Agreement with the University and Community College System of Nevada (UCCSN). The task is titled "The Experimental Determination of a "Redox Scale" for Assigning an Oxidizing/Reducing Potential to Groundwater from Wells in the Nye County Early Warning Drilling Program: A Scale for Predicting the Solubility and Mobility of Elements Commonly Found in Nuclear Wastes". The purpose of the research was to determine the concentrations of the various electrochemical oxidation states or redox species of eleven elements in groundwater samples collected from the Nye County …

Go to article

Maximum Likelihood Estimation Of Ordered Multinomial Parameters , Nicholas P. Jewell, Jack Kalbfleisch Oct 2003

Maximum Likelihood Estimation Of Ordered Multinomial Parameters , Nicholas P. Jewell, Jack Kalbfleisch

The University of Michigan Department of Biostatistics Working Paper Series

The pool-adjacent violator-algorithm (Ayer et al., 1955) has long been known to give the maximum likelihood estimator of a series of ordered binomial parameters, based on an independent observation from each distribution (see, Barlow et al., 1972). This result has immediate application to estimation of a survival distribution based on current survival status at a set of monitoring times. This paper considers an extended problem of maximum likelihood estimation of a series of ‘ordered’ multinomial parameters pi = (p1i, p2i, . . . , pmi) for 1 < = I < = k, where ordered means that pj1 < = pj2 < = .. . < = pjk for each j with 1 < = j < = m-1. The data consist of k independent observations X1, . . . ,Xk where Xi has a multinomial distribution with probability parameter pi and known index ni > = 1. By making use of variants of the pool adjacent violator algorithm, …

Go to article

On Textured Image Analysis Using Wavelets., Mausumi Acharyya Dr. Oct 2003

On Textured Image Analysis Using Wavelets., Mausumi Acharyya Dr.

Doctoral Theses

In image processing and computer vision research, we aim to derive better tools that give us different perspectives on the same image, allowing us to understand not only its content, but also its meaning and significance. Image processing can not compete with the human eye in terms of accuracy but it can outperform the latter easily on observational consistency, and ability to carry out detailed mathematical estimations. With time, image processing research has broadened from the basic pixel-based low- level operations to high-level analysis, that now includes the use of artificially intelligent techniques for image interpretation and understanding. These new …

Go to article

Coastal Observatory Investigates Energetic Current Oscillations On Southeast Florida Shelf, Alexander Soloviev, Rebekah J. Walker, Robert H. Weisberg, Mark E. Luther Oct 2003

Coastal Observatory Investigates Energetic Current Oscillations On Southeast Florida Shelf, Alexander Soloviev, Rebekah J. Walker, Robert H. Weisberg, Mark E. Luther

Marine & Environmental Sciences Faculty Articles

Coastal circulation along the southeast Florida shelf is strongly related to the dynamics of the Florida Current. The current follows the steep bottom terrain along the shelf break separating the deep ocean from the coastal zone (Figure 1 a, b). Energetic and complex flow regimes arise along the current's western edge, causing transient features such as sub-meso-scale eddies [Lee and Mayer, 1977; Shay et al., 2000] and energetic internal oscillations [Mooers, 1975; Soloviev et al., 2003], which affect mixing between the shelf and deeper ocean waters. Understanding of these regimes is important for modeling and prediction of the …

Go to article

Using Fecal Glucocorticoids For Stress Assessment In Mourning Doves, Brian E. Washburn, Joshua J. Millspaugh, John H. Schulz, Susan B. Jones, Tony Mong Oct 2003

Using Fecal Glucocorticoids For Stress Assessment In Mourning Doves, Brian E. Washburn, Joshua J. Millspaugh, John H. Schulz, Susan B. Jones, Tony Mong

United States Department of Agriculture Wildlife Services: Staff Publications

Fecal glucocorticoid assays provide a potentially useful, noninvasive means to study physiological responses of wildlife to various stressors. The objective of our study was to validate a method for measuring glucocorticoid metabolites in Mourning Dove (Zenaida macroura) feces. We validated the assay using standard procedures (e.g., parallelism, recovery of exogenous corticosterone) to demonstrate that the assay accurately and precisely measured glucocorticoid metabolites in Mourning Dove fecal extracts. We conducted adrenocorticotropin (ACTH) challenge experiments to validate the assay’s ability to determine biologically important changes in fecal glucocorticoids. Fecal glucocorticoid levels increased significantly approximately 2–3 hr after administration of ACTH …

Go to article

Effects Of Radio-Transmitters On Fecal Glucocorticoid Levels In Captive Dickcissels, Kimberly M. Suedkamp Wells, Brian E. Washburn, Joshua J. Millspaugh, Mark R. Ryan, Michael W. Hubbard Oct 2003

Effects Of Radio-Transmitters On Fecal Glucocorticoid Levels In Captive Dickcissels, Kimberly M. Suedkamp Wells, Brian E. Washburn, Joshua J. Millspaugh, Mark R. Ryan, Michael W. Hubbard

United States Department of Agriculture Wildlife Services: Staff Publications

We determined the effects of a leg-harness transmitter on fecal glucocorticoid levels of wild male Dickcissels (Spiza americana) in captivity. During the post-breeding season of 2001, we captured 10 male Dickcissels in central Missouri and housed them in individual pens of an outdoor aviary. We radio-tagged five birds; the other five were captured and handled, but were not radio-tagged. We collected fecal samples every other day prior to attachment (31 July– 21 August) and after attachment (24 August–20 September). Body condition and morphology were similar between control and transmitter-equipped birds. We observed a significant interaction between transmitter attachment …

Go to article

Nonparametric Estimation Of The Bivariate Recurrence Time Distribution, Chiung-Yu Huang, Mei-Cheng Wang Oct 2003

Nonparametric Estimation Of The Bivariate Recurrence Time Distribution, Chiung-Yu Huang, Mei-Cheng Wang

Johns Hopkins University, Dept. of Biostatistics Working Papers

This paper considers statistical models in which two different types of events, such as the diagnosis of a disease and the remission of the disease, occur alternately over time and are observed subject to right censoring. We propose nonparametric estimators for the joint distribution of bivariate recurrence times and the marginal distribution of the first recurrence time. In general, the marginal distribution of the second recurrence time cannot be estimated due to an identifiability problem, but a conditional distribution of the second recurrence time can be estimated non-parametrically. In literature, statistical methods have been developed to estimate the joint distribution …

Go to article

Clustering Of Galaxies At Z ∼ 3 Around The Probable Damped Lyα Absorber Toward Qso Apm 08279+5255, Nicolas Bouché, James D. Lowenthal Oct 2003

Clustering Of Galaxies At Z ∼ 3 Around The Probable Damped Lyα Absorber Toward Qso Apm 08279+5255, Nicolas Bouché, James D. Lowenthal

Astronomy: Faculty Publications

We present results on the clustering of Lyman break galaxies (LBGs) around a probable damped Lyα absorption line cloud (DLA) at z = 2.974 from deep UBVI images of the field containing the quasar APM 08279+5255 (z = 3.91). The large area covered by our images, 0.31 deg or ∼40 × 40 Mpc comoving at redshift z = 3, and their depth, μ (sky) ≃ 27.6 mag arcsec , allow us to identify ∼450 LBG candidates brighter than I = 24.80 at 2. 75 < z < 3.25 both close (50 kpc) to the DLA line of sight and up to 20 Mpc (comoving) from the DLA, i.e., physically unrelated. LBG candidates were identified using photometric redshift techniques that include the I magnitude as a prior estimate in addition to the colors. The two are combined using Bayes's theorem. This helps to break the degeneracies that occur in a pure spectral template fitting scheme. The overall rms is σ ≃ 0.15 at z ∼ 3 based on our analysis of photometric redshifts in the HDF-N. From the redshift likelihood distributions, we selected LBG galaxies within a redshift slice of width W = 0.15(≃ σ ) centered on the redshift of the DLA z . Within that redshift slice, we find an enhancement of galaxies near the DLA using both the surface density (Σ/Σ ≃ 3) and an estimator of the three-dimensional spatial overdensity (n/n̄ ∼ 5 ± 3). The surface overdensity Σ/Σ is significant at the more than 95% significance level on scales 2.5 < r < 5 Mpc comoving. The overdensity cannot be related to the QSO environment since the QSO is at z = 3.91. These results imply that some DLA could reside in high-density regions. We search within 45″ from the line of sight for galaxies responsible for the DLA and find one candidate with Z = 3.03 that is 26″ (145 kpc physical) away. From its magnitude I = 24.65 ± 0.2, its luminosity is M = -21.35. Due to its large impact parameter, however, this galaxy is not a likely candidate for the absorber. abs em I,AB AB z z z abs g g g θ em phot I,AB 2 -2

Go to article

Controlling H- Detachment With Few-Cycle Pulses, S. X. Hu, Anthony F. Starace Oct 2003

Controlling H- Detachment With Few-Cycle Pulses, S. X. Hu, Anthony F. Starace

Department of Physics and Astronomy: Faculty Publications

We present a detailed analysis of short-pulse detachment processes using few-cycle pulses with the aim of demonstrating means for controlling such processes. We first generalize the standard Keldysh-type formalism for laser-target interactions (in which final-state interaction between the detached electron and the core is ignored) to include the possibility that the vector potential is nonzero at the end of the interaction between a short laser pulse and the target. With this formalism in hand, we examine the effects of half-cycle pulses (HCPs) on detachment of the prototypical negative ion H–, and show that detachment by pairs of oppositely-directed (i.e., "bidirectional") …

Go to article

Fabrication Of Nonepitaxially Grown Double-Layered Fept:C/Feconi Thin Films For Perpendicular Recording, M.L. Yan, Xingzhong Li, L. Gao, Sy_Hwang Liou, David J. Sellmyer, R.J.M Van De Veerdonk, K.W. Wierman Oct 2003

Fabrication Of Nonepitaxially Grown Double-Layered Fept:C/Feconi Thin Films For Perpendicular Recording, M.L. Yan, Xingzhong Li, L. Gao, Sy_Hwang Liou, David J. Sellmyer, R.J.M Van De Veerdonk, K.W. Wierman

Sy-Hwang Liou Publications

A noneptaxially grown double-layered thin-film medium of nanocompsite FePt:C with a FeCoNi soft underlayer for high-density perpendicular magnetic recording was fabricated and investigated. Square-shaped perpendicular loops with a remanance ratio nearly equal to one and a coercivity as large as 8.5 kOe were obtained for this ordered FePt:C double-layered medium. The formation of the ordered L10 phase is confirmed by electron diffraction experiments. Transmission electron microscope observations reveal that FePt grains with a uniform size less than 5 nm are embedded in the C matrix and appear to be well isolated. Our results show that nonepitaxially grown (001) textured …

Go to article

Using The Intensity Modulation Index To Test Pulsar Radio Emission Models, Fredrick A. Jenet, Janusz Gil Oct 2003

Using The Intensity Modulation Index To Test Pulsar Radio Emission Models, Fredrick A. Jenet, Janusz Gil

Physics & Astronomy Faculty Publications

This Letter explores the possibility of testing pulsar radio emission models by observing pulse-to-pulse intensity modulation. It is shown that a relationship between a pulsar's period, period derivative, and intensity modulation is a natural consequence of at least one theoretical model of radio pulsar emission. It is proposed that other models may also predict a similar correlation. The exact form of the relationship will depend on the model in question. Hence, observations of intensity modulation should be able to determine the validity of the various emission models. In an attempt to search for the predicted dependencies, the modulation properties of …

Go to article

Gravitational Radiation From Pulsating White Dwarfs, Matthew Benacquista, M. Benacquista, D. M. Sedrakian, M. V. Hairapetyan, K. M. Shahabasyan, A. A. Sadoyan Oct 2003

Gravitational Radiation From Pulsating White Dwarfs, Matthew Benacquista, M. Benacquista, D. M. Sedrakian, M. V. Hairapetyan, K. M. Shahabasyan, A. A. Sadoyan

Physics & Astronomy Faculty Publications

Rotating white dwarfs undergoing quasi-radial oscillations can emit gravitational radiation in a frequency range from 0.1 to 0.3 Hz. Assuming that the energy source for the gravitational radiation comes from the oblateness of the white dwarf induced by the rotation, the strain amplitude is found to be ∼10-27 for a white dwarf at ∼50 pc. The Galactic population of these sources is estimated to be ∼107 and may produce a confusion-limited foreground for proposed advanced detectors in the frequency band between space-based and ground-based interferometers. Nearby oscillating white dwarfs may provide a clear enough signal to investigate white dwarf interiors …

Go to article

Liberating The Inflaton From Primordial Spectrum Constraints, Christian Armendariz-Picon Oct 2003

Liberating The Inflaton From Primordial Spectrum Constraints, Christian Armendariz-Picon

Physics - All Scholarship

I discuss a mechanism that renders the spectral index of the primordial spectrum and the inflationary stage independent of each other. If a scalar field acquires an appropriate time-dependent mass, it is possible to generate an adiabatic, Gaussian scale invariant spectrum of density perturbations during any stage of inflation. As an illustration, I present a simple model where the time-dependent mass arises from the coupling of the inflaton to a second scalar. The mechanism I propose might help to implement a successful inflationary scenario in particle physics theories that do not yield slow-roll potentials.

Go to article

Detection Of West Nile Virus Infection In Birds In The United States By Blocking Elisa And Immunohistochemistry, Martine Jozan, Richard Evans, Robert Mclean, Roy Hall, Basil Tangredi, Lisa Reed, Jamesina Scott Oct 2003

Detection Of West Nile Virus Infection In Birds In The United States By Blocking Elisa And Immunohistochemistry, Martine Jozan, Richard Evans, Robert Mclean, Roy Hall, Basil Tangredi, Lisa Reed, Jamesina Scott

United States Department of Agriculture Wildlife Services: Staff Publications

A blocking ELISA targeting an immunodominant West Nile epitope on the West Nile Virus NSI protein was assessed for the detection of West Nile-specific antibodies in blood samples collected from 584 sentinel chickens and 238 wild birds collected in New Jersey from May-December 2000. Ten mallard ducks (Anus platyrirynchos) experimentally infected with West Nile virus and six uninfected controls were also tested. The ELISA proved specific in detecting WNV antibodies in 9/10 chickens and 414 wild birds previously confirmed as positive by Plaque Reduction Neutralization test (PRNT) at the Center for Disease Control, Division of Vector Borne Diseases, …

Go to article

Spring Distribution Of Ring-Necked Pheasants (Phasianus Colchicus) Following Cattail Reduction With Glyphosate Herbicide, H.J. Homan, G. M. Linz, R.C. Carlson, W.J. Bleier Oct 2003

Spring Distribution Of Ring-Necked Pheasants (Phasianus Colchicus) Following Cattail Reduction With Glyphosate Herbicide, H.J. Homan, G. M. Linz, R.C. Carlson, W.J. Bleier

United States Department of Agriculture Wildlife Services: Staff Publications

To reduce blackbird (Icteridae) damage to field crops in the north-central United States. dense stands of cattail (Typha spp. ) are thinned with glyphosate herbicide. The stands become unusable as roosting and loafing sites, which helps to protect susceptible crops nearby, particularly sunflower (Helianthus annus). Landscape-level impacts of cattail management on non-target avian species have not been studied. We measured use of upland breeding territories by male ring-necked pheasants (Phasianus colchieus) following cattail reduction in wetlands used by pheasants for overwintering. In August 1992, glyphosate was applied to all wetlands with ≥70% cattail coverage in …

Go to article

Stored-Crop Loss Due To Deer Consumption, Kurt C. Vercauteren, Michael J. Pipas, Phil Peterson, Scott F. Beckerman Oct 2003

Stored-Crop Loss Due To Deer Consumption, Kurt C. Vercauteren, Michael J. Pipas, Phil Peterson, Scott F. Beckerman

United States Department of Agriculture Wildlife Services: Staff Publications

Deer (Odocoileus spp.) cause an estimated loss of $100 million in United States agricultural production each year (Conover 1997). In 1984 the Wisconsin Department of Agriculture, Trade and Consumer Protection surveyed producers in the state and estimated that white-tailed deer (Odocoileus virginianus) damage to all agricultural products exceeded $36 million annually (Wisconsin Department of Agriculture, Trade and Consumer Protection 1984). Nationwide, for stored crops alone, wildlife reportedly caused $26 million in losses in 1989 (Wywialowski 1994). Despite sometimes biased producer estimates of the value of wildlife-caused losses (Wywialowski 1994), many landowners are willing to accept a …

Go to article

Evaluation Of An Animal-Activated Scarecrow And A Monofilament Fence For Reducing Deer Use Of Soybean Fields, Jeff Beringer, Kurt C. Vercauteren, Joshua J. Millspaugh Oct 2003

Evaluation Of An Animal-Activated Scarecrow And A Monofilament Fence For Reducing Deer Use Of Soybean Fields, Jeff Beringer, Kurt C. Vercauteren, Joshua J. Millspaugh

United States Department of Agriculture Wildlife Services: Staff Publications

We measured the efficacy of an animal-activated scarecrow (AAS) and a 5-strand monofilament fence (MF) at reducing white-tailed deer (Odocoileus virginianus) use of 0.4-ha soybean plots in Missouri, USA. Our study design consisted of 9 soybean plots; 3 served as controls, 3 were surrounded by an MF, and 3 were surrounded by an AAS. Data collected for each protected plot included soybean height and weight taken from within and immediately adjacent to 10 unprotected, equally spaced 1 -m2 exclosures. A measure of deer use for each plot was collected with video cameras. A mixed-effects analysis of variance …

Go to article

Magnetic Storage Device Using Induced Magnetic Reversal Of A Cobalt Element Array, Hanning Chen, Scott L. Whittenburg Oct 2003

Magnetic Storage Device Using Induced Magnetic Reversal Of A Cobalt Element Array, Hanning Chen, Scott L. Whittenburg

Chemistry and Biochemistry Faculty Publications

The effects of the applied field, cell size, and cutting area on the ‘‘seed’’ induced magnetic reversal of a cobalt element array have been studied by a stochastic dynamic micromagnetics code using the Laudau–Lifshitz–Gilbert equation. Three magnetic reversal mechanisms under different magnitudes of the applied field have been investigated by examining the energy profiles. To minimize the effect of the thermal fluctuations on the switching time, an applied field with magnitude around 0.7 or 0.8 T and an element array with cutting area less than 10 nm X 10 nm are required. By using the smaller cellsize, the switching time …

Go to article

Coarse-Graining Description Of Solid Systems At Nonzero Temperature, Z.-B. Wu, Dennis J. Diestler, Ruqiang Feng, Xiao Cheng Zeng Oct 2003

Coarse-Graining Description Of Solid Systems At Nonzero Temperature, Z.-B. Wu, Dennis J. Diestler, Ruqiang Feng, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The quasicontinuum (QC) technique, in which the atomic lattice of a solid is coarse-grained by overlaying it with a finite-element mesh, has been employed previously to treat the quasistatic evolution of defects in materials at zero temperature. It is extended here to nonzero temperature. A coarse-grained Hamiltonian is derived for the nodes of the mesh, which behave as quasiparticles whose interactions are mediated by the underlying (non-nodal) atoms constrained to move in unison with the nodes. Coarse-grained thermophysical properties are computed by means of the Monte Carlo (MC) method. This dynamically constrained QC MC procedure is applied to a simple …

Go to article

Allowed Mesoscopic Point Group Symmetries In Domain Average Engineering Of Perovskite Ferroelectric Crystals, Dorian M. Hatch, H. T. Stokes, W. Cao Oct 2003

Allowed Mesoscopic Point Group Symmetries In Domain Average Engineering Of Perovskite Ferroelectric Crystals, Dorian M. Hatch, H. T. Stokes, W. Cao

Faculty Publications

In multivariant systems, several energetically degenerate low temperature domain states can be produced at the structural phase transition. Coexistence of these domain states can produce mesoscopic structures that possess symmetries distinct from the microscopic single domain crystal symmetry. Such engineered domain structures in certain ferroelectric materials have been proven to give superior piezoelectric properties and extremely soft shear moduli. The objective of this article is to consider the variety of symmetries that can be produced through domain average engineering in proper ferroelectric systems arising from the cubic Pm[overline 3]m symmetry perovskite structure.

Go to article

Origin And Implications Of The Observed Rhombohedral Phase In Nominally Tetragonal Pb(Zr0.35Ti0.65)O3 Thin Films, Paul C. Mcintyre, Alexei Gruverman, Bryan C. Hendrix, Steven M. Bilodeau, Jeffrey F. Roeder Oct 2003

Origin And Implications Of The Observed Rhombohedral Phase In Nominally Tetragonal Pb(Zr0.35Ti0.65)O3 Thin Films, Paul C. Mcintyre, Alexei Gruverman, Bryan C. Hendrix, Steven M. Bilodeau, Jeffrey F. Roeder

Alexei Gruverman Publications

The structural and electrical properties of Pb(Zr0.35Ti0.65)O3 (PZT) thin films ranging in thickness from 700 to 4000 Å have been investigated. These (001)/(100)-textured films were grown by metalorganic chemical vapor deposition on (111)-textured Ir bottom electrodes. It was observed that, in the as-deposited state, the thinnest PZT films are rhombohedral even though bulk PZT of this composition should be tetragonal. Thicker films have a layered structure with tetragonal PZT at the surface and rhombohedral PZT at the bottom electrode interface. In this article we investigate the origin of this structure and its effect of the …

Go to article

Solar Neutrinos, Sno And Neutrino-Deuteron Reactions, Vladimir Gudkov, Kuniharu Kubodera Oct 2003

Solar Neutrinos, Sno And Neutrino-Deuteron Reactions, Vladimir Gudkov, Kuniharu Kubodera

Faculty Publications

The standard nuclear physics approach and effective field theory approach for calculations of neutrino–deuteron cross sections for the solar neutrino energies are considered. Their main features, the level of accuracy and problems to be addressed for further developments are discussed.

Go to article

Density Matrix View Of The Double Well Problem, Ronald Lovett Oct 2003

Density Matrix View Of The Double Well Problem, Ronald Lovett

Topics in Quantum Mechanics

No abstract provided.

Go to article

Auroral Source Region: Plasma Properties Of The High-Latitude Plasma Sheet, C. A. Kletzing, J. D. Scudder, E. E. Dors, Carina Curto Oct 2003

Auroral Source Region: Plasma Properties Of The High-Latitude Plasma Sheet, C. A. Kletzing, J. D. Scudder, E. E. Dors, Carina Curto

Department of Mathematics: Faculty Publications

Statistical results from a survey of 93 passes through the high-latitude extension of the plasma sheet of electron data from the Hydra instrument on the Polar spacecraft show that the values for electron density can range from 0.01 to 0.5 cm–3 with an average value around 0.1 cm–3 on the poleward side and 0.3 cm–3 on the equatorward side. Electron mean energy is found to have an average value near 900 eV on the equatorward side and 400 eV on the poleward side but varies from 100 eV to 4 keV. These values for density and mean …

Go to article

Storage Coalescing, Delvin C. Defoe Oct 2003

Storage Coalescing, Delvin C. Defoe

All Computer Science and Engineering Research

Typically, when a program executes, it creates objects dynamically and requests storage for its objects from the underlying storage allocator. The patterns of such requests can potentially lead to internal fragmentation as well as external fragmentation. Internal fragmentation occurs when the storage allocator allocates a contiguous block of storage to a program, but the program uses only a fraction of that block to satisfy a request. The unused portion of that block is wasted since the allocator cannot use it to satisfy a subsequent allocation request. External fragmentation, on the other hand, concerns chunks of memory that reside between allocated …

Go to article

First Prev Next Last