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1997

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Articles 1741 - 1770 of 2184

Full-Text Articles in Physical Sciences and Mathematics

On The Dynamic Behaviour Of A Thermoviscoelastic Body In Frictional Contact With A Rigid Obstacle, Kenneth Kuttler, K. T. Andrews, M. Shillor Jan 1997

On The Dynamic Behaviour Of A Thermoviscoelastic Body In Frictional Contact With A Rigid Obstacle, Kenneth Kuttler, K. T. Andrews, M. Shillor

Faculty Publications

We consider the dynamic behaviour of a thermoviscoelastic body which may come into frictional contact with a rigid obstacle. The frictional contact is modelled by general contact and friction laws which include as special cases the power law normal compliance condition and the corresponding generalization of Coulomb's law of dry friction. The stress-strain constitutive relation is assumed to be of Kelvin-Voigt type and the frictional heat generation on the contact surface is taken into account. In this setting we establish the existence of a solution to a weak version of the energy-elasticity system which consists of a parabolic equation coupled …

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Improved Heterogeneous Distance Functions, Tony R. Martinez, D. Randall Wilson Jan 1997

Improved Heterogeneous Distance Functions, Tony R. Martinez, D. Randall Wilson

Faculty Publications

Instance-based learning techniques typically handle continuous and linear input values well, but often do not handle nominal input attributes appropriately. The Value Difference Metric (VDM) was designed to find reasonable distance values between nominal attribute values, but it largely ignores continuous attributes, requiring discretization to map continuous values into nominal values. This paper proposes three new heterogeneous distance functions, called the Heterogeneous Value Difference Metric (HVDM), the Interpolated Value Difference Metric (IVDM), and the Windowed Value Difference Metric (WVDM). These new distance functions are designed to handle applications with nominal attributes, continuous attributes, or both. In experiments on 48 applications …

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How Much Of The Nucleon Spin Is Carried By Glue?, Ian Balitsky, Xiangdong Ji Jan 1997

How Much Of The Nucleon Spin Is Carried By Glue?, Ian Balitsky, Xiangdong Ji

Physics Faculty Publications

We estimate in the QCD sum rule approach the amount of the nucleon spin carried by the gluon angular momentum: the sum of the gluon spin and orbital angular momenta. The result indicates that gluons contribute at least one half of the nucleon spin at the scale of 1GeV2.

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Time-Optimal Tree Computations On Sparse Meshes, D. Bhagavathi, V. Bokka, H. Gurla, S. Olariu, J. L. Schwing Jan 1997

Time-Optimal Tree Computations On Sparse Meshes, D. Bhagavathi, V. Bokka, H. Gurla, S. Olariu, J. L. Schwing

Computer Science Faculty Publications

The main goal of this work is to fathom the suitability of the mesh with multiple broadcasting architecture (MMB) for some tree-related computations. We view our contribution at two levels: on the one hand, we exhibit time lower bounds for a number of tree-related problems on the MMB. On the other hand, we show that these lower bounds are tight by exhibiting time-optimal tree algorithms on the MMB. Specifically, we show that the task of encoding and/or decoding n-node binary and ordered trees cannot be solved faster than Ω(log n) time even if the MMB has an infinite …

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Search For Lepton Flavor Violation In Ep Collisions At 300 Gev Center Of Mass Energy, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasiński, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, P. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti, G. Levi Jan 1997

Search For Lepton Flavor Violation In Ep Collisions At 300 Gev Center Of Mass Energy, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasiński, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, P. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti, G. Levi

Faculty Publications

Using the ZEUS detector at the HERA electron-proton collider, we have searched for lepton flavor violation in ep collisions at a center-of-mass energy (√s) of 300 GeV. Events of the type e + p → ℓ + X with a final-state lepton of high transverse momentum, ℓ = μ or τ, were sought. No evidence was found for lepton flavor violation in the combined 1993 and 1994 data samples, for which the integrated luminosities were 0.84 pb-1 for e-p collisions and 2.94 pb-1 for e+p collisions. Limits on coupling vs. mass are provided for leptoquarks and R-parity violating squarks. For …

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The Zeus Leading Proton Spectrometer And Its Use In The Measurement Of Elastic Ρ0 Photoproduction At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasiński, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, P. Bruni, G. Cara Romeo, G. Castellini, M. Chiarini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

The Zeus Leading Proton Spectrometer And Its Use In The Measurement Of Elastic Ρ0 Photoproduction At Hera, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. R. Okrasiński, J. Repond, R. Stanek, R. L. Talaga, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, P. Bruni, G. Cara Romeo, G. Castellini, M. Chiarini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

The differential cross section dσ/dt for elastic ρ0 photoproduction, γp → ρ0ρ (ρ0 → π+π-), has been measured in ep interactions at HERA. The squared four-momentum exchanged at the proton vertex, t, has been determined directly by measuring the momentum of the scattered proton using the ZEUS Leading Proton Spectrometer (LPS), a large scale system of silicon micro-strip detectors operating close to the HERA proton beam. The LPS allows the measurement of the momentum of high energy protons scattered at small angles with accuracies of 0.4% for the longitudinal momentum and 5 MeV for the transverse momentum. Photoproduction of ρ0 …

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Measurement Of Inelastic J/Ψ Photoproduction At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

Measurement Of Inelastic J/Ψ Photoproduction At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

No abstract provided.

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Comparison Of Zeus Data With Standard Model Predictions For E+P → E+X Scattering At High X And Q2, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

Comparison Of Zeus Data With Standard Model Predictions For E+P → E+X Scattering At High X And Q2, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

Using the ZEUS detector at HERA, we have studied the reaction e+p → e+X for Q2 > 5000 GeV2 with a 20.1 pb-1 data sample collected during the years 1994 to 1996. For Q2 below 15000 GeV2, the data are in good agreement with Standard Model expectations. For Q2 > 35000 GeV2, two events are observed while 0.145 ± 0.013 events are expected. A statistical analysis of a large ensemble of simulated Standard Model experiments indicates that with probability 6.0%, an excess at least as unlikely as that observed would occur above some Q2 cut. For x > 0.55 and y > 0.25, four …

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Measurement Of Elastic J/Ψ Photoproduction St Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

Measurement Of Elastic J/Ψ Photoproduction St Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

The reaction γ p → J/ψ p has been studied in ep interactions using the ZEUS detector at HERA. The cross section for elastic J/ψ photoproduction has been measured as a function of the photon-proton centre of mass energy W in the range 40 < W < 140 GeV at a median photon virtuality Q2 of 5 × 10-5 GeV2. The photoproduction cross section, σγp→J/ψp, is observed to rise steeply with W. A fit to the data presented in this paper to determine the parameter δ in the form σγp→J/ψp α Wδ yields the value δ = 0.92±0.14±0.10. The differential cross section dσ/d|t| is presented over the range |t| < 1.0 GeV2 where t is the square of the four-momentum exchanged at the proton vertex. dσ/d|t| falls exponentially with a slope parameter of 4.6 ± 0.4-0.6+0.4 GeV-2. The measured decay angular distributions are consistent with s-channel helicity conservation. © Springer-Verlag 1997.

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Study Of Photon Dissociation In Diffractive Photoproduction At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti Jan 1997

Study Of Photon Dissociation In Diffractive Photoproduction At Hera, J. Breitweg, M. Derrick, D. Krakauer, S. Magill, D. Mikunas, B. Musgrave, J. Repond, R. Stanek, R. L. Talaga, R. Yoshida, H. Zhang, Margarita C. K. Mattingly, F. Anselmo, P. Antonioli, G. Bari, M. Basile, L. Bellagamba, D. Boscherini, A. Bruni, G. Bruni, G. Cara Romeo, G. Castellini, L. Cifarelli, F. Cindolo, A. Contin, M. Corradi, S. De Pasquale, I. Gialas, P. Giusti, G. Iacobucci, G. Laurenti

Faculty Publications

Diffractive dissociation of quasi-real photons at a photon-proton centre of mass energy of W ≈ 200 GeV is studied with the ZEUS detector at HERA. The process under consideration is γp → XN, where X is the diffractively dissociated photon system of mass MX and N is either a proton or a nucleonic system with mass MN < 2 GeV. The cross section for this process in the interval 3 < MX < 24 GeV relative to the total photoproduction cross section was measured to be σDpartial/σtot = 6.2 ± 0.2(stat) ± 1.4(syst)%. After extrapolating this result to the mass interval of mφ2 < MX2 < 0.05W2 and correcting it for proton dissociation, the fraction of the total cross section attributed to single diffractive photon dissociation, γp → Xp, is found to be σSD/σtot = 13.3 ± 0.5(stat) ± 3.6(syst)%. The mass spectrum of the dissociated photon system in the interval 8 < MX < 24 GeV can be described by the triple pomeron (IP IP IP) diagram with an effective pomeron intercept of αIP(0) = 1.12 ± 0.04(stat) ± 0.08(syst). The cross section for photon dissociation in the range 3 < MX < 8 GeV is significantly higher than that expected from the triple pomeron amplitude describing the region 8 < MX < 24 GeV. Assuming that this discrepancy is due to a pomeron-pomeron-reggeon (IP IP IR) term, its contribution to the diffractive cross section in the interval 3 < MX < 24 GeV is estimated to be fIP IP IR = 26 ± 3(stat) ± 12(syst)%. © Springer-Verlag 1997.

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An Examination Of Environmental Sensitivity Among Supporters Of An Outdoor Recreation Area, Rodney James Blackman Jan 1997

An Examination Of Environmental Sensitivity Among Supporters Of An Outdoor Recreation Area, Rodney James Blackman

Dissertations and Theses @ UNI

The environment as an issue has been prominently before the public for over three decades. Yet the question of how much people know about the natural environment and how committed they are to the environment has seldom been considered in research literature. Research of this nature is needed because without it individuals interested in the preservation and conservation of the environment cannot be sure how their efforts to increase people's environmental sensitivity should be applied. The purpose of this study was to examine the level and extent of environmental sensitivity among supporters of an outdoor recreation area/facility in northeast Iowa. …

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Development Of A Tire Pyrolysis Process And Apparatus Using Steam Displacement Of The Combustible Atmosphere, Timothy Whitney Burrell Jan 1997

Development Of A Tire Pyrolysis Process And Apparatus Using Steam Displacement Of The Combustible Atmosphere, Timothy Whitney Burrell

Dissertations and Theses @ UNI

It is the purpose of this research to convert a batch vacuum pyrolysis process into a pyrolytic process that operates at ambient air pressure with the capabilities of a continuous material flow operation. Further, it is important to optimize the conditions of the pyrolysis process so as to reduce costs of operation and to reasonably maximize products that have value. Steam will be used to displace the combustible atmosphere which enables ambient air pressure operation and elimination of need for inert carrier gasses or evacuation of the apparatus. The use of steam also allows water traps to be used as …

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Radiation And Gas Exchange Of Understory Species At Boreas: Research Annual Performance Report For Period June 15, 1997- June 14, 1998, E. A. Walter-Shea, T. J. Arkebauer Jan 1997

Radiation And Gas Exchange Of Understory Species At Boreas: Research Annual Performance Report For Period June 15, 1997- June 14, 1998, E. A. Walter-Shea, T. J. Arkebauer

School of Natural Resources: Documents and Reviews

No abstract provided.

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Effects Of Red Imported Fire Ants On Recruitment Of White-Tailed Deer Fawns, Craig R. Allen, Stephen Demarais, R. Scott Lutz Jan 1997

Effects Of Red Imported Fire Ants On Recruitment Of White-Tailed Deer Fawns, Craig R. Allen, Stephen Demarais, R. Scott Lutz

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

We investigated the effect of red imported fire ants (RIFA; Solenopsis invicta) on an index of whitetailed deer (Odocoileus virginianus) fawn recruitment (doe:fawn ratio) on 10 200-ha plots in the Texas Coastal Prairie during 1991-93. Five of the plots received treatments of the fire ant bait AMDRO© (Am. Cyanamid Co., Wayne, N.].) during April and October 1991 and May 1992 to reduce RIFA populations. The remaining 5 plots served as untreated comparison areas. Populations of RIFA were reduced (P < 0.10) on treated study areas during deer fawning periods in 1991-92. Fawn recruitment was higher on treated areas during 1991 (P = 0.037) and 1992 (P = 0.069), with recruitment about twice as high on treated areas. In 1993, after 1 year of RIFA reinfestation, fawn recruitment did not differ between treated and untreated plots (P = 0.443). We conclude that high density RIFA infestations reduced white-tailed deer fawn recruitment.

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Effect Of Red Imported Fire Ant Envenomization On Neonatal American Alligators, Craig R. Allen, Kenneth G. Rice, Daniel P. Wojcik, H. Franklin Percival Jan 1997

Effect Of Red Imported Fire Ant Envenomization On Neonatal American Alligators, Craig R. Allen, Kenneth G. Rice, Daniel P. Wojcik, H. Franklin Percival

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Alligator populations in the southeastern United States have substantially recovered since the late 1960s when they were placed on the federal Endangered Species List (Joanen and McNease, 1987). In Florida, both early age class and adult animals currently are harvested for commercial and recreational purposes (Hines and Abercrombie, 1987). In addition, the alligator is ecologically important as a keystone species and as an indicator of wetland health (Mazzotti and Brandt, 1994). Recently, the nonnative ant Solenopsis invicta (the red imported fire ant) has surfaced as a potential threat to alligator populations. Solenopsis invicta is a relatively new (approx. 65 yr) …

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Atmospheric Correction Of Visible To Middle-Infrared Eos-Modis Data Over Land Surfaces: Background, Operational Algorithm And Validation, E. F. Vermote, N. El Saleous, C. O. Justice, Y. J. Kaufman, J. L. Privette, L. Remer, J. C. Roger, D. Tanre Jan 1997

Atmospheric Correction Of Visible To Middle-Infrared Eos-Modis Data Over Land Surfaces: Background, Operational Algorithm And Validation, E. F. Vermote, N. El Saleous, C. O. Justice, Y. J. Kaufman, J. L. Privette, L. Remer, J. C. Roger, D. Tanre

United States National Aeronautics and Space Administration: Publications

The NASA moderate resolution imaging spectroradiometer (MODIS) instrument will provide a global and improved source of information for the study of land surfaces with a spatial resolution of up to 250 m.

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Environmental Characteristics Of Black Crappie (Pomoxis Nigromaculatus) Nesting Sites In Two South Dakota Waters, K. L. Pope, D. W. Willis Jan 1997

Environmental Characteristics Of Black Crappie (Pomoxis Nigromaculatus) Nesting Sites In Two South Dakota Waters, K. L. Pope, D. W. Willis

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

A biotelemetry study was undertaken during spring 1995 to identify black crappie (Pomoxis nigromaculatus) nesting sites in two South Dakota water bodies. Individually coded ultrasonic transmitters were implanted into the body cavity of 15 adult male black crappie in each water body prior to spawning. Available habitat characteristics were recorded at 75 randomly selected sites within each water body, and habitat characteristics at nesting sites were recorded for each male black crappie believed to be nesting. Of the habitat characteristics analyzed, only substrate firmness did not differ (P=0.79) between water bodies. In Richmond Lake, black crappie selected nesting …

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Oxytetracycline Marking Efficacy For Yellow Perch Fingerlings And Temporal Assays Of Tissue Residues, Eric G. Unkenholz, Michael L. Brown, Kevin L. Pope Jan 1997

Oxytetracycline Marking Efficacy For Yellow Perch Fingerlings And Temporal Assays Of Tissue Residues, Eric G. Unkenholz, Michael L. Brown, Kevin L. Pope

Nebraska Cooperative Fish and Wildlife Research Unit: Staff Publications

Differentiating between hatchery and naturally reproduced fishes is difficult because of the lack of appropriate marking techniques. Chemical immersion techniques can be a practical method for mass marking juvenile fishes. The objectives of this study were to determine the concentration of oxytetracycline (OTC) hydrochloride needed to effectively mark age-0 yellow perch Perca flavescens to observe the retention lime of the mark, and to measure the persistence of OTC in body tissues. Fish were immersed in 309, 534, and 748 mg OTC/L for 12 h. Initial fish collections were made weekly, and monthly collections began 1 month postmarking for tissue and …

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1997 Rapid Ecological Assessment Northern Great Plains Steppe Ecoregion: Western And Central South Dakota, Northwestern Nebraska, Eastern Wyoming, A Final Report, Terri Hildebrand Jan 1997

1997 Rapid Ecological Assessment Northern Great Plains Steppe Ecoregion: Western And Central South Dakota, Northwestern Nebraska, Eastern Wyoming, A Final Report, Terri Hildebrand

Nebraska Game and Parks Commission: White Papers, Conference Presentations, and Manuscripts

In an effort to gain a more complete understanding of existing vegetative communities of the Northern Great Plains Steppe Ecoregion, rapid ecological assessment was undertaken throughout the ecoregion during the field season of 1997. Field office personnel of The Nature Conservancy and private contractors evaluated previously delineated regions in accordance with methodology determined in May of 1997. The following document presents results of the rapid ecological assessments performed by Hildebrand Contracting. The purpose of this document is to provide The Nature Conservancy with information to help determine the vegetative features of regions sampled. The specific areas and boundaries for evaluation …

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A Field Method For Quantifying Ammonium Picrate And Picric Acid In Soil, Philip G. Throne, Thomas F. Jenkins Jan 1997

A Field Method For Quantifying Ammonium Picrate And Picric Acid In Soil, Philip G. Throne, Thomas F. Jenkins

United States Army: Publications

A simple field method for the determination of ammonium picrate and picric acid in soil was developed. Picric acid is a strong acid with a pKa 5 0.80, and is colorless when dissolved in an organic solvent, whereas its anion ( picrate) is bright yellow. Picric acid and picrate ions were extracted from undried soil by shaking with acetone; any picric acid extracted was rapidly converted to picrate in the wet acetone. Picrate was extracted from the acetone soil extracts by passing the solutions through a solid-phase anion exchanger to remove interferences. Acidified acetone was used to convert the picrate …

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1997 Platte River Basin Ecosystem Symposium Proceedings Jan 1997

1997 Platte River Basin Ecosystem Symposium Proceedings

Water Current Newsletter

No abstract provided.

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Classical Interpretation Of The Quantum Description Of H- Photodetachment In Parallel E And B Fields, Qiaoling Wang, Anthony F. Starace Jan 1997

Classical Interpretation Of The Quantum Description Of H- Photodetachment In Parallel E And B Fields, Qiaoling Wang, Anthony F. Starace

Anthony F. Starace Publications

Total quantum mechanical cross sections for photodetachment of H- in parallel E and B fields are examined both analytically and numerically to extract information which has a classical interpretation, thereby complementing recent classical and semiclassical periodic orbit studies.

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Clusters Of Stars, Ileana Streinu Jan 1997

Clusters Of Stars, Ileana Streinu

Computer Science: Faculty Publications

We solve two open problems posed by Goodman and Pollack[GP84] about sets of signed circular permutations (clusters of stars) arising from generalized configurations of points: recognition and efficient reconstruction (drawing). As a biproduct we get an O(n2) space data structure constructible in O(n2) time, representing the order type of a (generalized) configuration of points and from which the orientation of each triple can be found in constant time, a problem posed in [EHN].

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Vertex-Edge Pseudo-Visibility Graphs: Characterization And Recognition, Joseph O'Rourke, Ileana Streinu Jan 1997

Vertex-Edge Pseudo-Visibility Graphs: Characterization And Recognition, Joseph O'Rourke, Ileana Streinu

Computer Science: Faculty Publications

We extend the notion of polygon visibility graphs to pseudo-polygons defined on generalized configurations of points. We consider both vertex-to-vertex, as well as vertex-to-edge visibility in pseudo-polygons. We study the characterization and recognition problems for vertex-edge pseudo-visibility graphs. Given a bipartite graph G satisfying three simple properties, which can all be checked in polynomial time, we show that we can define a generalized configuration of points and a pseudo-polygon on it, so that its vertex-edge pseudo-visibility graph is G. This provides a full characterization of vertex-edge pseudo-visibility graphs and a polynomial-time algorithm for the decision problem. It also implies that …

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Improving Minority Class Prediction Using Case-Specific Feature Weights, Claire Cardie, Nicholas Howe Jan 1997

Improving Minority Class Prediction Using Case-Specific Feature Weights, Claire Cardie, Nicholas Howe

Computer Science: Faculty Publications

This paper addresses the problem of handling skewed class distributions within the case-based learning (CBL) framework. We first present as a baseline an information gain-weighted CBL algorithm and apply it to three data sets from natural language processing (NLP) with skewed class distributions. Although overall performance of the baseline CBL algorithm is good, we show that the algorithm exhibits poor performance on minority class instances. We then present two CBL algorithms designed to improve the performance of minority class predictions. Each variation creates test-case-specific feature weights by first observing the path taken by the test case in a decision tree …

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Some Remarks On Solid State Polymerization, George Adler Jan 1997

Some Remarks On Solid State Polymerization, George Adler

Turkish Journal of Chemistry

No abstract provided.

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Dielectric Studies Of Various Olefin/So2 Copolmers, B. Baysal, Candan Erbi̇l, Paul L. Morganelli, W. H. Stockmayer Jan 1997

Dielectric Studies Of Various Olefin/So2 Copolmers, B. Baysal, Candan Erbi̇l, Paul L. Morganelli, W. H. Stockmayer

Turkish Journal of Chemistry

Dielectric constant and loss have been measured at low and high frequencies for several poly(1-olefin sulfones) as well as for the polysulfones of allybenzene and allyl cyclopentane. The low-frequency dispersion in allylbenzene due to helical sequences is weaker in benzene than in dioxane, and in both solvents is much lower than for the 1-olefin polymers. Solvent effects on the high frequency process are also reported, but yield no simple uniform picture.

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Synthesis Characterization And Miscibility Of Polyvinyl Butyrals Of Varying Vinyl Alcohol Contents, Z. M. Zhou, D. J. David, W. J. Macknight, F. E. Karasz Jan 1997

Synthesis Characterization And Miscibility Of Polyvinyl Butyrals Of Varying Vinyl Alcohol Contents, Z. M. Zhou, D. J. David, W. J. Macknight, F. E. Karasz

Turkish Journal of Chemistry

Polyvinyl butyrals (PVB) of systematically varying vinyl alcohol content have been synthesized and characterized using wet chemistry, IR, DSC, and TGA. The miscibility of PVB-PVB blends was studied by DSC as a function of vinyl alcohol content and vinyl alcohol content differences between the respective blend components. These data were use to construct an isothermal miscibility map of PVB and to calculate the intramolecular interaction parameter \chi_{VA,VB}. The \chi_{VA,VB} was a function of the absolute level of the vinyl alcohol (VA) and vinyl butyral (VB) contents of the polymers. In addition, the thermal stability of polyvinyl butyral was found to …

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Network Characterization Of Energetic Poly(Glycidyl-Azide), Mehmet S. Eroğlu, Olgun Güven Jan 1997

Network Characterization Of Energetic Poly(Glycidyl-Azide), Mehmet S. Eroğlu, Olgun Güven

Turkish Journal of Chemistry

Energetic poly(glycidyl azide) (PGA) elastomers with different crosslink densities were prepared by varying the NCO/OH reactive-groups ratio from 0.8 to 1.0. In the preparation of the elastomers, PGA chains were end-liked with a mixture of hexamethylene diisocyanate (HMDI) and trimethylol propane (TMP) at a fixed TMP/PGA mole ratio. The number average molar mass between junction points of the network chains \overline{{\rm M}}_c was calculated using data obtained from swelling and uniaxial tensile tests and the results were compared. For the mechanical characterization of the networks, Mooney-Rivlin plots were prepared and the values of the constants 2C_1 and 2C_2 of PGA …

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Synthesis Of The New Cation Exchange Resins Having Poly (Styrene-Caprolactone) Units, S. Savaşkan Yilmaz, Hulisi Özbayrak, Baki Hazer Jan 1997

Synthesis Of The New Cation Exchange Resins Having Poly (Styrene-Caprolactone) Units, S. Savaşkan Yilmaz, Hulisi Özbayrak, Baki Hazer

Turkish Journal of Chemistry

The crosslinked polystyrene-polycaprolactone , PS-PCL-, block copolymers were prepared by the copolymerization of styrene and poly(caprolacton dimethylmethacrylate) (PCL-DM). The molecular weights of polycaprolactone, PCL, PCL-DM were 1250 and 2000. The swelling in H_2O or CHCl_3 of the sulfonated and unsulfonated block copolymers were determined under comparable conditions and investigated. The capacities of the obtained ion exchange resins were 1.31 and 1.10 meq/g.

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