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1999

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Articles 1351 - 1380 of 2555

Full-Text Articles in Physical Sciences and Mathematics

Co Distribution And Kinematics Along The Bar In The Strongly Barred Spiral Ngc 7479, S Laine, J D P Kenny, Min S. Yun, S T. Gottesman Feb 1999

Co Distribution And Kinematics Along The Bar In The Strongly Barred Spiral Ngc 7479, S Laine, J D P Kenny, Min S. Yun, S T. Gottesman

Min S. Yun

We report on the 2farcs5 (400 pc) resolution CO (J=1→0) observations covering the whole length of the bar in the strongly barred late-type spiral galaxy NGC 7479. CO emission is detected only along a dust lane that traverses the whole length of the bar, including the nucleus. The emission is strongest in the nucleus. The distribution of emission is clumpy along the bar outside the nucleus and consists of gas complexes that are unlikely to be gravitationally bound. The CO kinematics within the bar consist of two separate components. A kinematically distinct circumnuclear disk, <500 pc in diameter, is undergoing predominantly circular motion with a maximum rotational velocity of 245 km s-1 at a radius of 1'' (160 pc). The CO-emitting gas in the bar outside the circumnuclear disk has substantial noncircular motions that are consistent with a large radial velocity component, directed inward. The CO emission has a large velocity gradient across the bar dust lane, ranging from 0.5 to 1.9 km s-1 pc-1 after correcting for inclination, and the projected velocity change across the dust lane is as high as 200 km s-1. This sharp velocity gradient is consistent with a shock front at the location of the bar dust lane. A comparison of Hα and CO kinematics across the dust lane shows that, although the Hα emission is often observed both upstream and downstream from the dust lane, the CO emission is observed only where the velocity gradient is large. We also compare the observations with hydrodynamic models and discuss star formation along the bar.

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Four Visions Of The Century Ahead: Will It Be Star Trek, Ecotopia, Big Government Or Mad Max?, Robert Costanza Feb 1999

Four Visions Of The Century Ahead: Will It Be Star Trek, Ecotopia, Big Government Or Mad Max?, Robert Costanza

Institute for Sustainable Solutions Publications and Presentations

Lays out different visions as to what the 21st century will be like. Where these visions are based; Default technological optimist vision; Technological skeptic's nightmare; War between public interest and private enterprise; Low-consumption sustainable vision; How society should decide among the visions; Challenges.

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Land Development And Biotechnology At The Claremont Colleges, Paul Faulstich Feb 1999

Land Development And Biotechnology At The Claremont Colleges, Paul Faulstich

Pitzer Faculty Publications and Research

Founded on the Oxford model of a cluster of institutions, the Claremont Colleges has periodically established a new school. In the Spring of 1997, the Board of Fellows of the Claremont University Center charged with policy-making for the consortium-voted to establish a seventh college; the Keck Graduate Institute of applied life sciences. or bioengineering. Despite other landholdings, including a golf course and a non-operational gravel quarry, the Board of Fellows voted to site the New Venture on a portion-approximately eleven acres--of the Bernard Biological Field Station. (Pitzer's vote was cast against building on the Field Station.)

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Woven Rope Friezes, Frank A. Farris, Nils Kristian Rossing Feb 1999

Woven Rope Friezes, Frank A. Farris, Nils Kristian Rossing

Mathematics and Computer Science

Here we present a complete set of recipes showing how to construct smooth curves with any desired frieze symmetry; we provide examples woven by Rossing for many of the pattern types, and invite readers to make others. We review the concept of frieze symmetry, develop the formulas for parametric equations with given symmetries, and pose some open questions raised by our analysis.

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Tight Linear Bounds On The Distance Between A Spline And Its B-Spline Control Polygon, David Lutterkort, Jörg Peters Feb 1999

Tight Linear Bounds On The Distance Between A Spline And Its B-Spline Control Polygon, David Lutterkort, Jörg Peters

Department of Computer Science Technical Reports

No abstract provided.

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Record Matching To Improve Data Quality, Vassilios S. Verykios, Ahmed K. Elmagarmid, Elias N. Houstis Feb 1999

Record Matching To Improve Data Quality, Vassilios S. Verykios, Ahmed K. Elmagarmid, Elias N. Houstis

Department of Computer Science Technical Reports

No abstract provided.

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Measurement Of The Mass Splittings Between The Bb̅ΧB,J(1P) States, K. W. Edwards, Kenneth A. Bloom, Cleo Collaboration Feb 1999

Measurement Of The Mass Splittings Between The Bb̅ΧB,J(1P) States, K. W. Edwards, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

We present new measurements of photon energies and branching fractions for the radiative transitions Υ(2S) → γχb(J=0,1,2)(1P). The masses of the χb states are determined from the measured radiative photon energies. The ratio of mass splittings between the χb substates, r ≡ [(MJ=2 -MJ=1)/( MJ=1 - MJ=0), with M the χb mass, provides information on the nature of the bb̅ confining potential. We find r(1P)=0.542 ±0.022±0.024. This value is somewhat lower than the previous world average, but more consistent with …

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Parity Violation In Neutron Resonances In 107,109ag, L Y. Lowie, J D. Bowman, J Corvi, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, H M. Shimizu Feb 1999

Parity Violation In Neutron Resonances In 107,109ag, L Y. Lowie, J D. Bowman, J Corvi, Bret E. Crawford, P P J. Delheij, C M. Frankle, M Iinuma, J N. Knudsen, A Masaike, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, E I. Sharapov, H M. Shimizu

Physics and Astronomy Faculty Publications

Parity nonconservation (PNC) was studied in p-wave resonances in Ag by measuring the helicity dependence of the neutron total cross section. Transmission measurements on natural Ag were performed in the energy range 32 to 422 eV with the time-of-flight method at the Manuel Lujan Neutron Scattering Center at Los Alamos National Laboratory. A total of 15 p-wave neutron resonances were studied in 107Ag and ninep-wave resonances in 109Ag. Statistically significant asymmetries were observed for eight resonances in 107Ag and for four resonances in109Ag. An analysis treating the PNC matrix elements as random variables yields a …

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Dislocation Scattering In Gan, David C. Look, J. R. Sizelove Feb 1999

Dislocation Scattering In Gan, David C. Look, J. R. Sizelove

Physics Faculty Publications

A theory of charged-dislocation-line scattering is developed within the framework of the Boltzmann transport equation. A fit of the theory to temperature-dependent Hall-effect data in GaN gives dislocation densities which are in excellent agreement with those measured by transmission electron microscopy. This work shows that threading edge dislocations in GaN indeed are electrically active, in agreement with recent theoretical predictions.

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Long-Term Prairie Falcon Population Changes In Relation To Prey Abundance, Weather, Land Uses, And Habitat Conditions, Karen Steenhof, Michael Kochert, Leslie B. Carpenter, Robert N. Lehman Feb 1999

Long-Term Prairie Falcon Population Changes In Relation To Prey Abundance, Weather, Land Uses, And Habitat Conditions, Karen Steenhof, Michael Kochert, Leslie B. Carpenter, Robert N. Lehman

United States Geological Survey: Staff Publications

We studied a nesting population of Prairie Falcons (Falco mexicanus) in the Snake River Birds of Prey National Conservation Area (NCA) from 1974-1997 to identify factors that influence abundance and reproduction. Our sampling period included two major droughts and associated crashes in Townsend's ground squirrel (Spermophilus townsendii) populations. The number of Prairie Falcon pairs found on long-term survey segments declined significantly from 1976-1997. Early declines were most severe at the eastern end of the NCA, where fires and agriculture have changed native shrubsteppe habitat. More recent declines occurred in the portion of canyon near the Orchard …

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Gas Turbine Engine Compressor- Combustor Dynamics Simulation Design, Sanford Fleeter, Elias N. Houstis, John R. Rice, Chem Zhou Feb 1999

Gas Turbine Engine Compressor- Combustor Dynamics Simulation Design, Sanford Fleeter, Elias N. Houstis, John R. Rice, Chem Zhou

Department of Computer Science Technical Reports

No abstract provided.

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Effect Of Uniform Electric Field On Homogeneous Vapor–Liquid Nucleation And Phase Equilibria. Ii. Extended Simple Point Charge Model Water, G.T. Gao, K.J. Oh, Xiao Cheng Zeng Feb 1999

Effect Of Uniform Electric Field On Homogeneous Vapor–Liquid Nucleation And Phase Equilibria. Ii. Extended Simple Point Charge Model Water, G.T. Gao, K.J. Oh, Xiao Cheng Zeng

Xiao Cheng Zeng Publications

The effects of a uniform electric field on homogeneous vapor–liquid nucleation of the extended simple point charge (SPC/E) model water have been simulated. A grand canonical Monte Carlo simulation approach [I. Kusaka et al., J. Chem. Phys. 108, 3416 (1998)], which directly gives the equilibrium distribution of physical clusters, is employed to calculate the formation free energy of the SPC/E water cluster. The results show that the formation free energy is lowered in a uniform field if the chemical potential of the supersaturated vapor is fixed; in this case, the field enhances the rate of nucleation. However, if the vapor …

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Magic "Squares" Indeed, Arthur T. Benjamin, Kan Yasuda '97 Feb 1999

Magic "Squares" Indeed, Arthur T. Benjamin, Kan Yasuda '97

All HMC Faculty Publications and Research

No abstract provided in this article.

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The Probe, Issue 197 – February 1999 Feb 1999

The Probe, Issue 197 – February 1999

The Probe: Newsletter of the National Animal Damage Control Association

A History of the Wildlife Services Program -- Donald W. Hawthorne, Gary L. Nunley, and Vivian Prothro, USDA-APHIS-Wildlife Services, Oklahoma and Texas Message from the President

Abstracts from the 5th Annual Conference of The Wildlife Society

Diverse Applications of Sharpshooting to Manage Abundant Deer Populations -- A.J. DeNicola, H.C. Frost, and K.E. Gustad.
Wildlife on Airports: A Fatal Attraction! -- R.A. DolbeerandS.E. Wright
An Empirical Model for Predicting Deer Population Trends in Suburban Chicago, Illinois -- DM. Etter, TJt. VanDeelen,R.E. Warner, andB.M. Hannon
Oral Vaccination Programs Against Canine Rabies in Texas -- M.G. Fearneyhough
Public Health and Safety Significance of …

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Search For Parity Violation In 93nb Neutron Resonances, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, K Fukuda, M Iinuma, J N. Knudsen, J Lokitz, L Y. Lowie, A Masaike, Y Matsuda, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, H M. Shimizu, Sharon L. Stephenson, Y-F Yen, V W. Yuan Feb 1999

Search For Parity Violation In 93nb Neutron Resonances, E I. Sharapov, J D. Bowman, Bret E. Crawford, P P J. Delheij, C M. Frankle, K Fukuda, M Iinuma, J N. Knudsen, J Lokitz, L Y. Lowie, A Masaike, Y Matsuda, Y Matsuda, G E. Mitchell, S I. Penttila, H Postma, N R. Roberson, S J. Seestrom, H M. Shimizu, Sharon L. Stephenson, Y-F Yen, V W. Yuan

Physics and Astronomy Faculty Publications

A new search has been performed for parity violation in the compound nuclear states of 94Nb by measuring the helicity dependence of the neutron total cross section. Transmission measurements on a thick niobium target were performed by the time-of-flight method at the Manuel Lujan Neutron Scattering Center with a longitudinally polarized neutron beam in the energy range 32 to 1000 eV. A total of 18 p-wave resonances in 93Nb were studied with none exhibiting a statistically significant parity-violating longitudinal asymmetry. An upper limit of 1.0×10-7 eV (95% confidence level) was obtained for the weak spreading widthΓw …

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Internal Temperature Of Douglas-Fir Buds Is Altered At Elevated Temperature, Martha E. Apple, Melissa S. Lucash, David M. Olszyk, David T. Tingey, Donald L. Phillips Feb 1999

Internal Temperature Of Douglas-Fir Buds Is Altered At Elevated Temperature, Martha E. Apple, Melissa S. Lucash, David M. Olszyk, David T. Tingey, Donald L. Phillips

Environmental Science and Management Faculty Publications and Presentations

Pseudotsuga menziesii (Douglas-fir) saplings were grown in sun-lit controlled environment chambers at ambient or elevated (4°C above ambient) temperature. We measured internal temperatures of vegetative buds with thermocouple probes and compared temperatures of normal buds and abnormal buds with loosened, rosetted outer scales in elevated temperature chambers. The abnormal buds had higher and earlier peak daily temperatures than normal buds. Elevated temperature may influence the internal temperature of buds and contribute to the development of abnormal, rosetted buds with loosened outer scales. Abnormal bud development may alter branching patterns and allometry of Douglas-fir trees subjected to climatic change.

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Structure-Function Relationships In The Pulmonary Arterial Tree, Christopher A. Dawson, Gary S. Krenz, Kelly Lynn Karau, Steven Thomas Haworth, Christopher C. Hanger, John H. Linehan Feb 1999

Structure-Function Relationships In The Pulmonary Arterial Tree, Christopher A. Dawson, Gary S. Krenz, Kelly Lynn Karau, Steven Thomas Haworth, Christopher C. Hanger, John H. Linehan

Mathematics, Statistics and Computer Science Faculty Research and Publications

Knowledge of the relationship between structure and function of the normal pulmonary arterial tree is necessary for understanding normal pulmonary hemodynamics and the functional consequences of the vascular remodeling that accompanies pulmonary vascular diseases. In an effort to provide a means for relating the measurable vascular geometry and vessel mechanics data to the mean pressure-flow relationship and longitudinal pressure profile, we present a mathematical model of the pulmonary arterial tree. The model is based on the observation that the normal pulmonary arterial tree is a bifurcating tree in which the parent-to-daughter diameter ratios at a bifurcation and vessel distensibility are …

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Heating Water Vapor In A Square Cavity Using Molecular And Particle Mechanics, Donald Greenspan Feb 1999

Heating Water Vapor In A Square Cavity Using Molecular And Particle Mechanics, Donald Greenspan

Mathematics Technical Papers

This paper explores the computer simulation of heating water vapor in a square cavity. Both molecular and particle mechanics are applied. A particular parameter called vel, found on the micro level, is shown to be applicable on the macro level in generating both laminar and turbulent flows.

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Source Water Assessment Plan, Water Quality Division Feb 1999

Source Water Assessment Plan, Water Quality Division

Publications (WR)

The safe drinking water amendments of 1996 placed a strong emphasis on the goal to establish a nationwide effort to protect drinking water sources. As part of that goal, the legislation provided for a preliminary assessment of drinking water sources and an inventory of surrounding adjacent land use (ALUs). This nationwide effort will result in the first comprehensive look at the nation's drinking water sources from an assessment perspective. One of the outcomes of this nationwide assessment will be information that public water systems (PWSs) can use to help determine appropriate monitoring frequencies and to protect their sources of drinking …

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Arizona Source Water Assessment Plan Final Draft, Arizona Department Of Environmental Quality Feb 1999

Arizona Source Water Assessment Plan Final Draft, Arizona Department Of Environmental Quality

Publications (WR)

The safe drinking water amendments of 1996 placed a strong emphasis on the goal to establish a nationwide effort to protect drinking water sources. As part of that goal, the legislation provided for a preliminary assessment of drinking water sources and an inventory of surrounding adjacent land use (ALUs). This nationwide effort will result in the first comprehensive look at the nation's drinking water sources from an assessment perspective. One of the outcomes of this nationwide assessment will be information that public water systems (PWSs) can use to help determine appropriate monitoring frequencies and to protect their sources of drinking …

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Survey Of Military Applications For Fourier Transform Infrared (Ftir) Spectroscopy, Robert G. Hauser Feb 1999

Survey Of Military Applications For Fourier Transform Infrared (Ftir) Spectroscopy, Robert G. Hauser

Theses and Dissertations

This paper surveyed four potential military uses for a Fourier Transform Infrared (FTIR) Spectrometer. A physical method to retrieve vertical atmospheric temperature profiles using a least-squares solution on atmospheric radiance observed at the surface in the 4.3-micrometer carbon dioxide absorption band was analyzed. The method was not successful. Weighting functions, calculated from the surface looking up, were a maximum at the surface, so no unique solution for temperature retrieval by height was determined. Observed atmospheric radiance measurements were compared with radiance calculated using the Moderate Resolution Transmittance Code (MODTRAN). Qualitative comparison showed spectral features of observed and calculated radiance plots …

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Shoreline Management Plan With Habitat Enhancement For Town Of Saxis, Virginia, C. Scott Hardaway Jr., Donna A. Milligan, George R. Thomas, Rebecca C.H. Brindley, Lyle M. Varnell, Walter L. Priest, Sharon Dewing Feb 1999

Shoreline Management Plan With Habitat Enhancement For Town Of Saxis, Virginia, C. Scott Hardaway Jr., Donna A. Milligan, George R. Thomas, Rebecca C.H. Brindley, Lyle M. Varnell, Walter L. Priest, Sharon Dewing

Reports

The goal of the present study is to identify the best course of action to manage shoreline erosion in Saxis and to provide a detailed Shoreline Management Plan with Habitat Enhancement which can be presented to potential State and Federal funding agencies. While the Plan itself will not resolve the erosion conditions in Saxis, it will allow the Town to market its need and the method of resolution of this need, to agencies and leaders with the resources to implement the Plan’s suggested actions. The shoreline management plan will provide the necessary level of shoreline stabilization while minimizing adverse impacts …

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Stellar Kinematics Of The Double Nucleus Of M31, Thomas S. Statler, Ivan R. King, Philippe Crane, Robert I. Jedrzejewski Feb 1999

Stellar Kinematics Of The Double Nucleus Of M31, Thomas S. Statler, Ivan R. King, Philippe Crane, Robert I. Jedrzejewski

Dartmouth Scholarship

We report observations of the double nucleus of M31 with the f/48 long-slit spectrograph of the Hubble Space Telescope Faint Object Camera. We obtain a total exposure of 19,000 s over seven orbits, with the 0063-wide slit along the line between the two brightness peaks (P.A. 42°). Careful correction of the raw data for detector backgrounds and geometric distortion is essential. A spectrum of Jupiter obtained with the same instrument is used as a spectral template to extract rotation and velocity dispersion profiles by cross-correlation. The rotation curve is resolved and reaches a maximum amplitude of ~250 km s-1 roughly …

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A Quadratic Fredholm Integral Equation And Its Solution For Various Kernels, Merlynd K. Nestell, Mostafa Ghandehari Feb 1999

A Quadratic Fredholm Integral Equation And Its Solution For Various Kernels, Merlynd K. Nestell, Mostafa Ghandehari

Mathematics Technical Papers

Consider the Fredholm integral equation [see pdf for notation], a parameter. The solution of this equation is discussed for separable, difference and distribution kernels. Existence, uniqueness and bifurcation questions are explored for various assumptions on the kernel.

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Anisotropic Magnetoresistance In The Organic Superconductor Β″–(Bedt-Ttf)2sf5ch2cf2so3, X. Su, F. Zuo, J. A. Schlueter, Jack M. Williams, P. G. Nixon, Rolf Walter Winter, Gary L. Gard Feb 1999

Anisotropic Magnetoresistance In The Organic Superconductor Β″–(Bedt-Ttf)2sf5ch2cf2so3, X. Su, F. Zuo, J. A. Schlueter, Jack M. Williams, P. G. Nixon, Rolf Walter Winter, Gary L. Gard

Chemistry Faculty Publications and Presentations

In this paper, we report transport measurements of interlayer magnetoresistance with field parallel and perpendicular to the current direction in an all organic superconductor β″–(BEDT-TTF)₂SF₅CH₂CF₂SO₃. For H∥I, the isothermal magnetoresistance R(H) at low temperatures (T

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Vims Shoreline Permit Database Impacts And Alterations Summary 1988 - 1992, Walter I. Priest Iii, Lyle M. Varnell, Thomas A. Barnard, Julie G. Bradshaw, Kirk J. Havens, Carl Hershner, Pamela Mason, William L. Roberts, Virginia Institute Of Marine Science, Wetlands Program Feb 1999

Vims Shoreline Permit Database Impacts And Alterations Summary 1988 - 1992, Walter I. Priest Iii, Lyle M. Varnell, Thomas A. Barnard, Julie G. Bradshaw, Kirk J. Havens, Carl Hershner, Pamela Mason, William L. Roberts, Virginia Institute Of Marine Science, Wetlands Program

Reports

No abstract provided.

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Test-Hole Drilling Program In Nebraska, Duane R. Mohlman Feb 1999

Test-Hole Drilling Program In Nebraska, Duane R. Mohlman

Conservation and Survey Division

No abstract provided.

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Exposure To Atmospheric Radon, Daniel J. Steck, R. William Field, Charles F. Lynch Feb 1999

Exposure To Atmospheric Radon, Daniel J. Steck, R. William Field, Charles F. Lynch

Physics Faculty Publications

We measured radon (222Rn) concentrations in Iowa and Minnesota and found that unusually high annual average radon concentrations occur outdoors in portions of central North America. In some areas, outdoor concentrations exceed the national average indoor radon concentration. The general spatial patterns of outdoor radon and indoor radon are similar to the spatial distribution of radon progeny in the soil. Outdoor radon exposure in this region can be a substantial fraction of an individual's total radon exposure and is highly variable across the population. Estimated lifetime effective dose equivalents for the women participants in a radon-related lung cancer …

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Single-Change Circular Covering Designs, John P. Mcsorley Feb 1999

Single-Change Circular Covering Designs, John P. Mcsorley

Articles and Preprints

A single-change circular covering design (scccd) based on the set [v] = {1, . . . ,v} with block size k is an ordered collection of b blocks, B = {B1, . . . ,Bb}, each Bi ⊂ [v], which obey: (1) each block differs from the previous block by a single element, as does the last from the first, and, (2) every pair of [v] is covered by some Bi. The object is to minimize b for a fixed v and k. …

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Elastic And Shear Moduli Of Single-Walled Carbon Nanotube Ropes, Nancy Burnham, Jean-Paul Salvetat, G Andrew D Briggs, Jean-Marc Bonard, Revathi Bacsa, Andrzej Kulik, Thomas Stöckli, László Forró Jan 1999

Elastic And Shear Moduli Of Single-Walled Carbon Nanotube Ropes, Nancy Burnham, Jean-Paul Salvetat, G Andrew D Briggs, Jean-Marc Bonard, Revathi Bacsa, Andrzej Kulik, Thomas Stöckli, László Forró

Nancy A. Burnham

Carbon nanotubes are believed to be the ultimate low-density high-modulus fibers, which makes their characterization at nanometer scale vital for applications. By using an atomic force microscope and a special substrate, the elastic and shear moduli of individual single-walled nanotube (SWNT) ropes were measured to be of the order of 1 TPa and 1 GPa, respectively. In contrast to multiwalled nanotubes, an unexpectedly low intertube shear stiffness dominated the flexural behavior of the SWNT ropes. This suggests that intertube cohesion should be improved for applications of SWNT ropes in high-performance composite materials.

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