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1999

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Articles 1 - 30 of 2201

Full-Text Articles in Physical Sciences and Mathematics

Dynamics Of The Dbi Spike Soliton, David Kastor, Jennie Traschen Dec 1999

Dynamics Of The Dbi Spike Soliton, David Kastor, Jennie Traschen

David Kastor

We compare oscillations of a fundamental string ending on a D3-brane in two different settings: (1) a test-string radially threading the horizon of an extremal black D3-brane and (2) the spike soliton of the DBI effective action for a D3-brane. Previous work has shown that overall transverse modes of the test-string appear as l=0 modes of the transverse scalar fields of the DBI system. We identify DBI world-volume degrees of freedom that have dynamics matching those of the test-string relative transverse modes. We show that there is a map, resembling T-duality, between relative and overall transverse modes for the ...


Viscoelastic Depinning Of Driven Systems: Mean-Field Plastic Scallops, M. Cristina Marchetti, Alan Middleton, Thomas Prellberg Dec 1999

Viscoelastic Depinning Of Driven Systems: Mean-Field Plastic Scallops, M. Cristina Marchetti, Alan Middleton, Thomas Prellberg

Physics

We have investigated the mean field dynamics of an overdamped viscoelastic medium driven through quenched disorder. The model introduced incorporates coexistence of pinned and sliding degrees of freedom and can exhibit continuous elastic depinning or first order hysteretic depinning. Numerical simulations indicate mean field instabilities that correspond to macroscopic stick-slip events and lead to premature switching. The model is relevant for the dynamics of driven vortex arrays in superconductors and other extended disordered systems.


A Continuous Sampling Air-Icp For Metals Emission Monitoring, David P. Baldwin, Daniel S. Zamzow, David E. Eckels, George P. Miller Dec 1999

A Continuous Sampling Air-Icp For Metals Emission Monitoring, David P. Baldwin, Daniel S. Zamzow, David E. Eckels, George P. Miller

Chemistry Conference Papers, Posters and Presentations

An air-inductively coupled plasma (air-ICP) system has been developed for continuous sampling and monitoring of metals as a continuous emission monitor (CEM). The plasma is contained in a metal enclosure to allow reduced-pressure operation. The enclosure and plasma are operated at a pressure slightly less than atmospheric using a Roots blower, so that sample gas is continuously drawn into the plasma. A Teflon sampling chamber, equipped with a sampling pump, is connected to the stack that is to be monitored to isokinetically sample gas from the exhaust line and introduce the sample into the air-ICP. Optical emission from metals in ...


The Reflectance Spectrum Of Human Skin, Elli Angelopoulou Dec 1999

The Reflectance Spectrum Of Human Skin, Elli Angelopoulou

Technical Reports (CIS)

The automated detection of human skin has become an important task for machine vision systems. Prior vision and graphics research on this topic has primarily focused on images acquired with conventional color cameras. Formal spectrographic analyses have largely been undertaken in the medical domain and focus on the detection of pathology. We have constructed a facility capable of producing accurate, dense and repeatable reflectance measurements. The light reflected from the skin is measured using a high resolution, high accuracy spectrograph under precisely calibrated lighting conditions. This paper presents observations from the first body of data gathered at this facility. From ...


Emissions Of Formaldehyde, Acetic Acid, Methanol, And Other Trace Gases From Biomass Fires In North Carolina Measured By Airborne Fourier Transform Infrared Spectroscopy, Robert J. Yokelson, Jon G. Goode, Darold E. Ward, Ronald A. Susott, Ronald E. Babbitt, D. D. Wade, Issac T. Bertschi, David W. T. Griffith, Wei Min Hao Dec 1999

Emissions Of Formaldehyde, Acetic Acid, Methanol, And Other Trace Gases From Biomass Fires In North Carolina Measured By Airborne Fourier Transform Infrared Spectroscopy, Robert J. Yokelson, Jon G. Goode, Darold E. Ward, Ronald A. Susott, Ronald E. Babbitt, D. D. Wade, Issac T. Bertschi, David W. T. Griffith, Wei Min Hao

Chemistry and Biochemistry Faculty Publications

Biomass burning is an important source of many trace gases in the global troposphere. We have constructed an airborne trace gas measurement system consisting of a Fourier transform infrared spectrometer (FTIR) coupled to a “flow-through” multipass cell (AFTIR) and installed it on a U.S. Department of Agriculture Forest Service King Air B-90. The first measurements with the new system were conducted in North Carolina during April 1997 on large, isolated biomass fire plumes. Simultaneous measurements included Global Positioning System (GPS); airborne sonde; particle light scattering, CO, and CO2; and integrated filter and canister samples. AFTIR spectra acquired within ...


Nanocomposite Copt:C Films For Extremely High-Density Recording, M. Yu, Yi Liu, A. Moser, D. Weller, David J. Sellmyer Dec 1999

Nanocomposite Copt:C Films For Extremely High-Density Recording, M. Yu, Yi Liu, A. Moser, D. Weller, David J. Sellmyer

David Sellmyer Publications

Nanocomposite CoPt:C films were investigated as potential media for extremely high-density recording. An annealing temperature of over 600 °C is necessary to form nanocomposite CoPt:C films consisting of C matrix and fct CoPt nanocrystallites with grain sizes of 8–20 nm and coercivities of 3–12 kOe. Coercivity and grain size increase with increasing annealing temperature and decreasing C concentration and they are insensitive to film thickness. The average activation volumes are about 0.9×10-18 cm3. The properties of these nanocomposite CoPt:C films can be tailored to satisfy the thermal stability, coercivity, and media ...


Electrical Resistivity Of A Thin Metallic Film, Horacio E. Camblong Dec 1999

Electrical Resistivity Of A Thin Metallic Film, Horacio E. Camblong

Physics and Astronomy

The electrical resistivity of a pure sample of a thin metallic film is found to depend on the boundary conditions. This conclusion is supported by a free-electron model calculation and confirmed by an ab initio relativistic Korringa-Kohn-Rostoker computation. The low-temperature resistivity is found to be zero for a free-standing film (reflecting boundary conditions) but nonzero when the film is sandwiched between two semi-infinite samples of the same material (outgoing boundary conditions). In the latter case, this resistivity scales inversely with the number of monolayers and is due to the background diffusive scattering by a finite lattice.


Breeding Bird Census On Four Shelterwood-Cut Stands In Buckingham County, Virginia, Sally Ann Statham Dec 1999

Breeding Bird Census On Four Shelterwood-Cut Stands In Buckingham County, Virginia, Sally Ann Statham

Theses, Dissertations & Honors Papers

The Breeding Bird Census (BBC) technique was used to study breeding bird populations on two paired shelter wood-cut oak stands in Buckingham County, Virginia. The four plots are part of a study to determine oak regeneration following controlled burns in the Virginia piedmont. There is an interest in determining how shelter wood-cut plots affect the breeding birds of Virginia. A total of twenty-seven bird species established and defended territories among the four plots. Ten bird species defended territories on all four plots. All of these species were birds characteristic of forest habitats.


A Patching Model For Surface Tension Of Spherical Droplet And Tolman Length. Ii, T.V. Bykov, Xiao Cheng Zeng Dec 1999

A Patching Model For Surface Tension Of Spherical Droplet And Tolman Length. Ii, T.V. Bykov, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

In the framework of density functional theory (DFT), two patching models for the density profile of spherical liquid droplet are developed. The patching is based on analytical expressions of the asymptote of the density profiles. The first model leads to analytic expressions of the Tolman length and the effective rigidity constant, from which the temperature dependence of the Tolman length and effective rigidity constant can be determined. The second model is developed particularly for small spherical droplets, from which the dependence of chemical potential and the surface tension of the droplet on the radius are obtained. The results are compared ...


Quasicrystalline Nature Of Quasicrystal Surfaces: A Photoemission Study, D. Naumović, P. Aebi, :L. Schlapbach, C. Beeli, Thomas A. Lograsso, Dwight W. Delaney Dec 1999

Quasicrystalline Nature Of Quasicrystal Surfaces: A Photoemission Study, D. Naumović, P. Aebi, :L. Schlapbach, C. Beeli, Thomas A. Lograsso, Dwight W. Delaney

Ames Laboratory Publications

Differently prepared surfaces of quasicrystalline i-Al-Pd-Mn are analyzed using angle-resolved photoemission in the x-ray andultraviolet range of photon energies. Depending on the preparation, we find both surfaces with crystalline structure and metallic character, and surfaces with quasicrystalline structural fingerprints and a suppressed density of states at the Fermi level, compatible with a pseudogap.


Synthesis And Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations: Model Studies For The Preparation Of The 8E,10Z,16E,18E-Tetraene Segment Of Macrolactin A, Abdel-Aziz S. El-Ahl, Young Yun, William Donaldson Dec 1999

Synthesis And Reactivity Of Acyclic (Pentadienyl)Iron(1+) Cations: Model Studies For The Preparation Of The 8E,10Z,16E,18E-Tetraene Segment Of Macrolactin A, Abdel-Aziz S. El-Ahl, Young Yun, William Donaldson

Chemistry Faculty Research and Publications

The dicarbonyl(1,2-dimethylpentadienyl)triphenylphosphineiron(1+) cation (11) has been prepared from methyl 4-methyl-2E,4E-hexadienoate in four steps. The cation (11) reacts with hydride and carbon nucleophiles in a regiospecific fashion to afford (3-methyl-2E,4Z-diene)iron complexes. Dicarbonyl(3-methyl-7-nitro-2E,4Z-heptadiene)triphenylphosphineiron (15), the product from the reaction of 11 with nitromethane anion, has been utilized as a precursor for nitrile oxide–olefin cyclocondensations.


Minmax Trees: Efficient Relational Operation Support For Hierarchical Data Exploration, Ionel D. Stroe, Elke A. Rundensteiner, Matthew O. Ward Dec 1999

Minmax Trees: Efficient Relational Operation Support For Hierarchical Data Exploration, Ionel D. Stroe, Elke A. Rundensteiner, Matthew O. Ward

Computer Science Faculty Publications

This paper presents a new method for implementing hierarchical navigation operations in relational database systems as required for applications such as interactive visual explorations over large datasets. A particular class of recursive unions of joins and divisions that operate on hierarchies has been identified. By using adequate pre-computation (i.e., organizing the hierarchical structure as what we called a MinMax tree), the recursive processing of the operations in this class is shown to be reducible to range queries. Extensions of the method for non-tree as well as dynamic hierarchies have also been designed. We implemented our technique using Oracle 7 ...


Fundamental Plane Distances To Early-Type Field Galaxies In The South Equatorial Strip. I. The Spectroscopic Data, K. R. Müller, G. Wegner, S. Raychaudhury, W. Freudling Dec 1999

Fundamental Plane Distances To Early-Type Field Galaxies In The South Equatorial Strip. I. The Spectroscopic Data, K. R. Müller, G. Wegner, S. Raychaudhury, W. Freudling

Open Dartmouth: Peer-reviewed articles by Dartmouth faculty

Radial velocities and central velocity dispersions are derived for 238 E/S0 galaxies from medium-resolution spectroscopy. New spectroscopic data have been obtained as part of a study of the Fundamental Plane distances and peculiar motions of early-type galaxies in three selected directions of the South Equatorial Strip, undertaken in order to investigate the reality of large-scale streaming motion; results of this study have been reported in M\"uller $et$ $al.$ (1998). The new APM South Equatorial Strip Catalog (−17.5 < δ < +2.5) was used to select the sample of field galaxies in three directions: (1) 15h10 – 16h10; (2) 20h30 – 21h50; (3) 00h10 – 01h30. The spectra obtained have a median S/N per ̊A of 23, an in- strumental resolution (FWHM) of ∼ 4 ̊A, and the spectro- graph resolution (dispersion) is ∼ 100 km s−1. The Fourier cross-correlation method was used to derive the radial ve- locities and velocity dispersions. The velocity dispersions have been corrected for the size of the aperture and for the galaxy effective radius. Comparisons of the derived radial velocities with data from the literature show that our values are accurate to 40 km s−1. A comparison with results from Jørgensen et al. (1995) shows that the derived central velocity dispersion have an rms scatter of 0.036 in log σ. There is no offset relative to the velocity dispersions of Davies et al. (1987).


Interaction Second Virial Coefficients From A Recent H2-Co Potential Energy Surface, J. Gottfried, George C. Mcbane Dec 1999

Interaction Second Virial Coefficients From A Recent H2-Co Potential Energy Surface, J. Gottfried, George C. Mcbane

Peer Reviewed Articles

No abstract provided.


Langmuir Monolayers As Disordered Solids: Disorder And Elastic Fluctuations In Mesophases , Tadeusz Luty, Craig J. Eckhardt, Jacques Lefebvre Dec 1999

Langmuir Monolayers As Disordered Solids: Disorder And Elastic Fluctuations In Mesophases , Tadeusz Luty, Craig J. Eckhardt, Jacques Lefebvre

Craig J. Eckhardt Publications

Ordering in Langmuir monolayer mesophases is examined using an approach based on the elastic theory of crystals. Molecular tails are modeled as ‘‘defects’’ grafted onto a two-dimensional elastic medium and are characterized by elastic dipoles. It is assumed that disorder in the parent, LS, phase is due to competition between local (within a domain) and global (hexagonal arrangement of domains) structure. By treating the LS phase as a mixture of rectangular and/or oblique domains (rectangular and/or oblique defects within the two-dimensional elastic medium), density fluctuations due to elastic interactions between domains are analyzed. The correlation function for the ...


Noncommutative Computer Algebra In The Control Of Singularly Perturbed Dynamical Systems, J. W. Helton, F. Dell Kronewitter, Mark Stankus Dec 1999

Noncommutative Computer Algebra In The Control Of Singularly Perturbed Dynamical Systems, J. W. Helton, F. Dell Kronewitter, Mark Stankus

Mathematics

Most algebraic calculations which one sees in linear systems theory, for example in IEEE TAC, involve block matrices and so are highly noncommutative. Thus conventional commutative computer algebra packages, as in Mathematica and Maple, do not address them. Here we investigate the usefulness of noncommutative computer algebra in a particular area of control theory-singularly perturbed dynamic systems-where working with the noncommutative polynomials involved is especially tedious. Our conclusion is that they have considerable potential for helping practitioners with such computations. For example, the methods introduced here take the most standard textbook singular perturbation calculation, [KK086], one step further than had ...


Peculiar Velocities Of Nonlinear Structure: Voids In Mcvittie Spacetime, Sakai, Nobuyuki, Haines, Paul Dec 1999

Peculiar Velocities Of Nonlinear Structure: Voids In Mcvittie Spacetime, Sakai, Nobuyuki, Haines, Paul

Open Dartmouth: Peer-reviewed articles by Dartmouth faculty

As a study of peculiar velocities of nonlinear structure, we analyze the model of a relativistic thin-shell void in the expanding universe. (1) Adopting McVittie (MV) spacetime as a background universe, we investigate the dynamics of an uncompensated void with negative MV mass. Although the motion itself is quite different from that of a compensated void, as shown by Haines & Harris (1993), the present peculiar velocities are not affected by MV mass. (2) We discuss how precisely the formula in the linear perturbation theory applies to nonlinear relativistic voids, using the results in (1) as well as the previous results ...


An Adaptation Of Krylov Subspace Methods To Path Following Problems, Homer F. Walker Dec 1999

An Adaptation Of Krylov Subspace Methods To Path Following Problems, Homer F. Walker

Mathematical Sciences Faculty Publications

A procedure is outlined for adapting Krylov subspace methods to solving approximately the underdetermined linear systems that arise in path following (continuation, homotopy) methods. This procedure, in addition to preserving the usual desirable features of Krylov subspace methods, has the advantages of satisfying orthogonality constraints exactly and of not introducing ill-conditioning through poor scaling.


Creation Of An Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, S. Kulin, L. A. Orozco, C. Orzel, S. L. Rolston Dec 1999

Creation Of An Ultracold Neutral Plasma, Scott D. Bergeson, T. C. Killian, S. Kulin, L. A. Orozco, C. Orzel, S. L. Rolston

Faculty Publications

We report the creation of an ultracold neutral plasma by photoionization of laser-cooled xenon atoms. The charge carrier density is as high as 2×10^9 cm^-3, and the temperatures of electrons and ions are as low as 100 mK and 10 uK, respectively. Plasma behavior is evident in the trapping of electrons by the positive ion cloud when the Debye screening length becomes smaller than the size of the sample. We produce plasmas with parameters such that both electrons and ions are strongly coupled.


Variability Of Soil And Landscape Properties Related To Precision Agriculture, Thomas E. Fenton Dec 1999

Variability Of Soil And Landscape Properties Related To Precision Agriculture, Thomas E. Fenton

Proceedings of the Integrated Crop Management Conference

Soil survey involves the mapping, classification, correlation, and interpretation of soils. The first soil survey in Iowa was in the Dubuque County area but did not include the entire county. The field work was done in 1902 and the report was published in 1903. Since that time, most Iowa counties have had at least two soil surveys completed and some have had three. The basic factors of soil formation have not changed but the use of the soils for intensive agriculture has resulted in changes in some soil properties, especially of the surface horizons. However, generally factors other than soil ...


The Pesticide Decision Tool: A Field-Level Approach To Integrating Envionmental Factors In Pesticide Decision Making, John Vickery Dec 1999

The Pesticide Decision Tool: A Field-Level Approach To Integrating Envionmental Factors In Pesticide Decision Making, John Vickery

Proceedings of the Integrated Crop Management Conference

The Institute for Agriculture and Trade Policy (IATP) is working to reduce the environmental impacts of agriculture and improve water quality through the voluntary adoption of on-farm assessment and decision tools. The objective of the Pesticide Decision Tool (PDT) project is to facilitate the integration of environmental risk assessment in the selection and management of pesticides in arable crop production. It is designed for use by agricultural professional such as co-op and elevator agronomists, independent crop consultants, and Natural Resources Conservation Service (NRCS), Soil and Water Conservation District, and university Extension specialists, as well as by farmers. We take a ...


Soil Phosphorus Testing For Crop Production And Environmental Purposes, Antonio Mallarino Dec 1999

Soil Phosphorus Testing For Crop Production And Environmental Purposes, Antonio Mallarino

Proceedings of the Integrated Crop Management Conference

Increasing animal production in the state or its concentration in certain areas is increasing the amounts of manure being applied to the land. Often, the manure is applied at rates or at a frequency that exceed the phosphorus (P) needs of crops and even the amount removed in harvested products. Animal manure can supply the nitrogen (N) and P needed by crops as well as other nutrients. Due to its relative N and P content and potential N losses, however, continued use of rates that supply the N removed in com grain (and in soybean grain too) results in P ...


Making Every Fertilizer Dollar Pay, John E. Sawyer Dec 1999

Making Every Fertilizer Dollar Pay, John E. Sawyer

Proceedings of the Integrated Crop Management Conference

In an ideal crop production system, all nutrient and limestone needs would be determined by evaluating expected return from each input, without required purchases being limited by overall financial resources. More realistically, resources get allocated by priority need, and decisions related to fertilizer and limestone use are judged against other crop production needs, enterprise requirements, and overall farm business goals. This allocation becomes especially pertinent when cash flow is low and financial resources become inadequate. In this situation, and considering all potential inputs, the focus should be on garnering the greatest return to each input dollar expended. Prioritizing fertilizer and ...


Year In Review - 1999, Annis Water Resources Institute Dec 1999

Year In Review - 1999, Annis Water Resources Institute

AWRI Reviews

No abstract provided.


12. Pierre Sigwalt, Otto Vogl Dec 1999

12. Pierre Sigwalt, Otto Vogl

Emeritus Faculty Author Gallery

No abstract provided.


17th International Herman F. Mark Symposium: Polypropylene - A Material Of The Future, Otto Vogl, Helga Roder Dec 1999

17th International Herman F. Mark Symposium: Polypropylene - A Material Of The Future, Otto Vogl, Helga Roder

Emeritus Faculty Author Gallery

No abstract provided.


Grundlagenreflexionen Zur Thematik Anthropomorpher Schnittstellen, Rudolf Kaehr Dec 1999

Grundlagenreflexionen Zur Thematik Anthropomorpher Schnittstellen, Rudolf Kaehr

Rudolf Kaehr

Report for the EMBASSI Project


Segment Analysis Of Sucker Brook: The Location Of Sources Of Pollution, Joseph C. Makarewicz, Theodore W. Lewis, Stephen Lewandowski Dec 1999

Segment Analysis Of Sucker Brook: The Location Of Sources Of Pollution, Joseph C. Makarewicz, Theodore W. Lewis, Stephen Lewandowski

Technical Reports

Sucker Brook is located in the northwest portion of the Canandaigua Lake watershed, Ontario County, New York (Figs. 1 and 2). The relatively large watershed encompasses 6.9 square miles and flows into Canandaigua Lake at the City of Canandaigua. The Canandaigua Lake Watershed Task Force with the assistance of the Ontario County Planning Department and the Soil and Water Conservation District has monitored Sucker Brook since 1996 in collaboration with the State University of New York at Brockport's Center for Applied Aquatic Science and Aquaculture (CAASA). Monitoring efforts have included the installation of a permanent gauging and sampling ...


Carleson Measure And Some Classes Of Meromorphic Functions, Rauno Aulaskari, Hasi Wulan, Ruhan Zhao Dec 1999

Carleson Measure And Some Classes Of Meromorphic Functions, Rauno Aulaskari, Hasi Wulan, Ruhan Zhao

Mathematics Faculty Publications

No abstract provided.


Synthesis And Characterization Of Metal Ion Sensing High Performance Polymers And Directional Metallopolymers, Odessa N. Petzold Dec 1999

Synthesis And Characterization Of Metal Ion Sensing High Performance Polymers And Directional Metallopolymers, Odessa N. Petzold

ETD Collection for AUC Robert W. Woodruff Library

High performance polyamides containing the 4,4’-disubstituted-2,2’-bipyridyl moiety were synthesized by phosphorylation polycondensation from 2,2’-bipyridyl-4,4’-dicarboxylic acid and a series of primary aromatic diamines with triphenylphosphite and pyridine as the agents to facilitate condensation. Polyamides exhibiting improved solubility in organic solvents and strong acids, melting transitions at low temperatures and good thermal properties were prepared by introducing bulky methyl and fluoro groups, flexible ether and propyl linkages, and by using monomers with reduced symmetry. Solutions of the polyamides with rigid mainchains (II, III, IV, V, VI, and VIII) showed birefringence (colorful spherulites) at concentrations ...