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1997

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Articles 151 - 180 of 2184

Full-Text Articles in Physical Sciences and Mathematics

Study On Perchlorate Produced By Electrolysis With Oxygen Cathode, Zhigang Shao, Baolian Yi, Naichao Li, Ming Han Nov 1997

Study On Perchlorate Produced By Electrolysis With Oxygen Cathode, Zhigang Shao, Baolian Yi, Naichao Li, Ming Han

Journal of Electrochemistry

A new method of measuring the flow capacity of cell gas in the perchlorate cell process equipped with an oxygen cathode is applided to investigate the influence of changes in the concentration of solution (chloride, chlorate, perchlorate and metal ion) and changes in the operation parameters (current density, temperature and pH) on perchlorate current efficiency. The main abstacle that the oxygen cathode is used in the perchlorate cell process is put forward and a method is provided to resolve it.

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The Effect Of Solution Composition On The Corrosion Behavior Of Electrodeposited Zinc Powder, Qingwen Li, Qin Yang, Xi Xia Nov 1997

The Effect Of Solution Composition On The Corrosion Behavior Of Electrodeposited Zinc Powder, Qingwen Li, Qin Yang, Xi Xia

Journal of Electrochemistry

Zinc powder as a widely anode material can be electrowon from ZnCl2 or ZnO+KOH media. The properties of zinc powder are likely to be modified with electrolytic conditions such as the composition of bath solution, electrolysis manner, current density and additives etc.. In this paper, we have discussed the effect of the compositions of bath solution on the microstructure and corrosion resistance of zinc powder.

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The Activity Of Alloy Cu-Ni Electrode In Electroreduction Of Aromatic Nitro-Compounds, Chunan Ma, Shaoping Tong, Xiaojun Cheng, Hui Wang Nov 1997

The Activity Of Alloy Cu-Ni Electrode In Electroreduction Of Aromatic Nitro-Compounds, Chunan Ma, Shaoping Tong, Xiaojun Cheng, Hui Wang

Journal of Electrochemistry

Cu-Ni alloy on the basis of copper at different ratio Cu/Ni are prepared by codepostion. The cathode activtiy of film are studied by steady-state polarization for electroreduction nitro-benzene (NB) and 1,5-dinitroanthraquinone (1,5-DNA) to p-aminophenol and 1,5-diamino-4,8-dihydroanthraquinone respectly. The results show that the alloy cathodes at different ratio Cu/Ni have different exchange current density (io) and apparent activition energy (EA). The alloy (CN-30) has maximal io and minimal EA by codeposition at the following conditions: electrolyte: 0.05 mol/L CuSO4·5H2O+0.6 mol/L NiSO4·6H2O+0.25 mol/L Na3Cit·2H2O; …

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Photoluminescence Of Photoelectrochemically Etched N+-Si, Guozheng Li, Chengqian Zhang, Xiumei Yang Nov 1997

Photoluminescence Of Photoelectrochemically Etched N+-Si, Guozheng Li, Chengqian Zhang, Xiumei Yang

Journal of Electrochemistry

PS layer on n+-Si with (111) orientation prepered by means of photoelectrochemically etched has photo-luminescent (PL) ability like PS layer on usual n-Si. The data of PL spectra and quenching are given.

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The Initial Process Of Amophous Electroless Nickel, Yi Chi, Lei Zhang, Yijan Wang, Maoyuan Ma Nov 1997

The Initial Process Of Amophous Electroless Nickel, Yi Chi, Lei Zhang, Yijan Wang, Maoyuan Ma

Journal of Electrochemistry

The initial process and mophology of electroless nickel played a domination role in adhesive strenghth of EN coating. The structure of initial deposits on certain matrixes was observed by TEM analysis. The deposition of a extremaly fine grain film depended on relative contrast between a coating and a matrix in crystal lattice parameters. When the coating and matrix had similar srystal lattice parameters. A extremely fine grain film was obtained. On the contrary, when the crystal lattice parameters were very different, a amorphous structure was observed.

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Development Of A New Type Ni-S Evolution Hydrogen Electrode For Water Electrolysis, Xiaoyou Yuan, Jinyu Wang Nov 1997

Development Of A New Type Ni-S Evolution Hydrogen Electrode For Water Electrolysis, Xiaoyou Yuan, Jinyu Wang

Journal of Electrochemistry

A new type evolution hydrogen electrode NiS(N) has been made from nickel plating electrode in NiSO4CS(NH2)2 bath by electrodeposition. It is analyzed by SEM and X-ray energy spectrum. The NiS(N) electrode is different from the NiS(O) electrode (which is used in plant at present time) in surface metallograph configuration and surfer content. The results of measurement polarization curves and water electrolysis 480 hours at 5 000 A·m-2 show that the evolution hydrogen overpotential of NiS(N) electrode is decreased at least 160 mV relative to NiS(O) electrode and the stablisum of NiS(N) electrode is better …

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Molten Carbonate Fuel Cell Materials And Technology, Naichao Li, Baolian Yi Nov 1997

Molten Carbonate Fuel Cell Materials And Technology, Naichao Li, Baolian Yi

Journal of Electrochemistry

Molten Carbonate Fuel Cell materials are reviewed, and the technology of Molten Carbonate Fuel Cell are discussed.

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Calculation Of The Sacrificial Anode Resistance Utilizing Boundary Element Method, Jianhua Wu, Mingxian Sun, Guangzhou Liu, Guangzhang Chen Nov 1997

Calculation Of The Sacrificial Anode Resistance Utilizing Boundary Element Method, Jianhua Wu, Mingxian Sun, Guangzhou Liu, Guangzhang Chen

Journal of Electrochemistry

According to a kind of mathematic model set up for the cathodic protection potential field, the boundary element method (BEM) was used to study the working state of plate sacrificial anodes which were galvanically coupled to mild steel. In situ experiment showed that the current output and resistance of sacrificial anodes could be calculated more accurately using BEM than loiyd formula. On the basis of the calculation, the cathodic protection design would be more accurate. It was also investigated that the effect of the length to breadth ratio (L/B) on current output and resistance of plate zinc anodes. The results …

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The Effect Of Bismuth On Microstructure Of The Cathodic Copper Deposition Of Copper Electrorefining, Daorong Lu, Jianxing Lin Nov 1997

The Effect Of Bismuth On Microstructure Of The Cathodic Copper Deposition Of Copper Electrorefining, Daorong Lu, Jianxing Lin

Journal of Electrochemistry

The electrocrystal formation, crystal orientation and the chemical composition of the cathodic copper deposition in the presence of Bi3+ in the electrolyte of acidified CuSO4 are studies by scanning electron microscopy, X-ray diffraction, atomic absorption and EDAM. The results indicate that the Bi could′t deposit on cathode when copper electrolysed at common current density i=200 A·mol/L-2 and t=60 ℃. Bi3+ scarcely effected on the crystal orientation (220) of copper deposition. High concentration Bi3+ in the electrolyte promoted (220) growth and inhibited the other crystal orientation growth. Bi3+ effected on electrocrystal formation and the cell …

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Study On The Electrochemical Behaviour Of Eu(Ⅲ) Tryptophane Imidazole Triple Complex, Huixia Wu, Zemin Wang, Xiaqin Wu, Haifeng Yang, Zongrang Zhand Nov 1997

Study On The Electrochemical Behaviour Of Eu(Ⅲ) Tryptophane Imidazole Triple Complex, Huixia Wu, Zemin Wang, Xiaqin Wu, Haifeng Yang, Zongrang Zhand

Journal of Electrochemistry

Eu(Ⅲ) Tryptophane Imidazole binary and triple complexes were synthesized. IR spectra indicate that the carboxy group of tryptophane and the N atom of imidazole are coordinated with Eu(Ⅲ) ion. Cyclic voltammetry was used to study the electrochemical behaviour of Eu(Ⅲ) ion, the mixture of Eu(Ⅲ) with tryptophane and imidazole, and Eu(Ⅲ) binary or triple complexes. Among the scan range of -0.4～-1.0 V (vs. SCE), all of these three kinds of systems depicted pseudoreversible electron transfer. The kinetic parameters including D and Ks were also evaluated.

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Observation Of Scaling Violations In Scaled Momentum Distributions 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 Nov 1997

Observation Of Scaling Violations In Scaled Momentum Distributions 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

Charged particle production has been measured in deep inelastic scattering (DIS) events over a large range of x and Q2 using the ZEUS detector. The evolution of the scaled momentum, xp, with Q2, in the range 10 to 1280 GeV2, has been investigated in the current fragmentation region of the Breit frame. The results show clear evidence, in a single experiment, for scaling violations in scaled momenta as a function of Q2. © 1997 Elsevier Science B.V.

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Market-Based Resource Control For Mobile Agents, Jonathan Bredin, David Kotz, Daniela Rus Nov 1997

Market-Based Resource Control For Mobile Agents, Jonathan Bredin, David Kotz, Daniela Rus

Computer Science Technical Reports

Mobile agents are programs that can migrate from machine to machine in a heterogeneous, partially disconnected network. As mobile agents move across a network, they consume resources. We discuss a system for controlling the activities of mobile agents that uses electronic cash, a banking system, and a set of resource managers. We describe protocols for transactions between agents. We present fixed-pricing and dynamic-pricing policies for resources. We focus on and analyze the sealed-bid second-price auction as a mechanism for dynamic pricing.

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Low-Field Hole Mobility In A Photorefractive Polymer, Arosha Goonesekera, Stephen Ducharme, James M. Takacs, Lei Zhang Nov 1997

Low-Field Hole Mobility In A Photorefractive Polymer, Arosha Goonesekera, Stephen Ducharme, James M. Takacs, Lei Zhang

Stephen Ducharme Publications

We present the time-of-flight measurements of hole mobility in a photorefractive polymer composite as a function of temperature and applied electric field. The analysis shows that the temperature dependence of the low-field mobility is in apparent disagreement with the predictions of the Gaussian disorder model and also with polaron models.

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Mechanisms Of Change: Do Lemons Whistle?, James Burke Nov 1997

Mechanisms Of Change: Do Lemons Whistle?, James Burke

James R. Thompson Leadership Lectures

Award-winning science historian, author and screenwriter James Burke was born in Northern Ireland and educated at Jesus College, Oxford University, where he received his Master of Arts Degree in English Literature. Upon leaving Oxford, Burke taught at the universities of Bologna and Urbino, Italy and was director of the English Schools at Bologna and at Rome. He also was a contributor to the production of the major Italian-English dictionary (Zanichelli).

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Upper Hillsborough River Diagnostic Watershed Assessment Final Project Report, Limno-Tech, Inc. (Lti), Southwest Florida Water Management District (Swfwmd) Nov 1997

Upper Hillsborough River Diagnostic Watershed Assessment Final Project Report, Limno-Tech, Inc. (Lti), Southwest Florida Water Management District (Swfwmd)

Reports

This report was prepared under a contract between Limno-Tech, Inc. (L TI) and the Southwest Florida Water Management District (SWFWMD) for a diagnostic assessment study of the Upper Hillsborough River watershed. The Hillsborough River drains more than 695 mi2 of predominantly agricultural lands in Pasco, Polk, and Hillsborough Counties. The present investigation focused on a 650 mi2 area encompassing the northern and central drainage segments of the Hillsborough River Watershed (Figure E-1). Of particular concern to this investigation is the Hillsborough River reservoir, which is designated as a Class I water based on its use as a potable water supply. …

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Limit On The Two-Photon Production Of The Glueball Candidate FJ(2220) At The Cornell Electron Storage Ring, R. Godang, Kenneth A. Bloom, Cleo Collaboration Nov 1997

Limit On The Two-Photon Production Of The Glueball Candidate FJ(2220) At The Cornell Electron Storage Ring, R. Godang, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

We use the CLEO detector at the Cornell e+e- storage ring, CESR, to search for the two-photon production of the glueball candidate fJ (2220) in its decay to KsKs. We present a restrictive upper limit on the product of the two-photon partial width and the KsKs branching fraction, (Γγγ BKsKs)fJ(2220). We use this limit to calculate a lower limit on the stickiness, which is a measure of the two-gluon coupling relative to the two-photon coupling. This limit on stickiness …

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Study Of The Decay Τ-→2Π-Π+3Π0ΝΤ, S. Anderson, Kenneth A. Bloom, Cleo Collaboration Nov 1997

Study Of The Decay Τ-→2Π-Π+3Π0ΝΤ, S. Anderson, Kenneth A. Bloom, Cleo Collaboration

Kenneth Bloom Publications

The decay τ-→2π-π+3π0ντ has been studied with the CLEO II detector at the Cornell Electron Storage Ring. The branching fraction is measured to be (2.85 ± 0.56 ± 0.51) X 10-4. The result is in good agreement with the isospin expectation but somewhat below the conserved-vectorcurrent prediction. We have searched for resonance substructure in the decay. Within the statistical precision, the decay is saturated by the channels τ-→π-2π0ωντ, 2π-π+ωντ, and π-2π0ων …

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Upper Limits To The Outflow Of Ions At Mars: Implications For Atmospheric Evolution, Jane L. Fox Nov 1997

Upper Limits To The Outflow Of Ions At Mars: Implications For Atmospheric Evolution, Jane L. Fox

Physics Faculty Publications

Escape of ions is potentially important for the evolution of volatiles on Mars, but the mechanisms and rates of ion escape processes are not fully understood. Instruments on the Russian Phobos 2 orbiter have, however, measured fluxes of heavy ions apparently of ionospheric origin in the optical shadow of Mars. These ions are assumed to arise from escape processes induced by the interaction of the solar wind with the ionosphere. We determine here upper limits to the ion loss rates by imposing upward flux boundary conditions on models of the low and high solar activity Mars ionosphere. The maximum fluxes …

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Characterizing The Coherence Of Bose-Einstein Condensates And Atom Lasers, R. J. Dodd, Charles W. Clark, Mark Edwards, Keith Burnett Nov 1997

Characterizing The Coherence Of Bose-Einstein Condensates And Atom Lasers, R. J. Dodd, Charles W. Clark, Mark Edwards, Keith Burnett

Physics & Astronomy: Faculty Publications

For a dilute, interacting Bose gas of magnetically-trapped atoms at temperatures below the critical temperature T 0 for Bose-Einstein condensation, we determine the second-order coherence function g (2)(r 1, r 2) within the framework of a finite-temperature quantum field theory. We show that, because of the different spatial distributions of condensate and thermal atoms in the trap, g (2)(r 1, r 2) does not depend on |r 1 - r 2| alone. This means that the experimental determinations of g (2) reported to date give only its spatial average. Such an average may underestimate the degree of coherence attainable in …

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Observation Of Isolated High-ET Photons In Photoproduction At Hera: Zeus Collaboration, 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 Nov 1997

Observation Of Isolated High-ET Photons In Photoproduction At Hera: Zeus Collaboration, 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

Events containing an isolated prompt photon with high transverse energy, together with a balancing jet, have been observed for the first time in photoproduction at HERA. The data were taken with the ZEUS detector, in a γp centre of mass energy range 120-250 GeV. The fraction of the incoming photon energy participating in the production of the prompt photon and the jet, xγ, shows a strong peak near unity, consistent with LO QCD Monte Carlo predictions. In the transverse energy and pseudorapidity range 5 ≤ EγT < 10 GeV, -0.7 ≤ ηγ < 0.8, EjetT ≥ 5 GeV, and -1.5 ≤ ηjet ≤ 1.8, with xOBSγ > 0.8, the measured cross section is 15.3 ± 3.8 ± 1.8 pb, in good …

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The Reform Calculus Debate And The Psychology Of Learning Mathematics, James M. Cargal Nov 1997

The Reform Calculus Debate And The Psychology Of Learning Mathematics, James M. Cargal

Humanistic Mathematics Network Journal

No abstract provided.

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Teaching Mathematics Appreciation To Nonscience Majors, Josefina Alvarez Nov 1997

Teaching Mathematics Appreciation To Nonscience Majors, Josefina Alvarez

Humanistic Mathematics Network Journal

No abstract provided.

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Poems, David L. Finn Nov 1997

Poems, David L. Finn

Humanistic Mathematics Network Journal

No abstract provided.

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Borsuk-Ulam Implies Brouwer: A Direct Construction, Francis E. Su Nov 1997

Borsuk-Ulam Implies Brouwer: A Direct Construction, Francis E. Su

All HMC Faculty Publications and Research

No abstract provided in this article.

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Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Xi. Intensive Monitoring Of The Ultraviolet Spectrum Of Ngc 7469, I. Wanders, Bradley M. Peterson, D. Alloin, T.R. Ayres, J. Clavel, D. Michael Crenshaw, K. Horne, Gerard A. Kriss, Julian Henry Krolik, Matthew A. Malkan, Hagai Netzer, Paul T. O'Brien, G.A. Reichert, P.M. Rodriguez-Pascual, W. Wamsteker, T. Alexander, K. S.J. Anderson, E. Benitez, N.G. Bochkarev, A.N. Burenkov, F.-Z. Cheng, S.J. Collier, A. Comastri, M. Dietrich, D. Dultzin-Hacyan, B.R. Espey, A. V. Filippenko, C. Martin Gaskell, I.M. George, M.R. Goad, L.C. Ho, Shai Kaspi, W. Kollatschny, Kirk T. Korista, Ari Laor, G.M. Macalpine, M. Mignoli, S.L. Morris, K. Nandra, S. Penton, Richard William Pogge, R.L. Ptak, J.M. Rodriguez-Espinoza, M. Santos-Lleo, A.I. Shapovalova, J.M. Shull, Stephanie A. Snedden, L.S. Sparke, G.M. Stirpe, W.-H. Sun, T.J. Turner, M.-H. Ulrich, T.-G. Wang, C. Wei, W.F. Welsh, S.-J. Xue, Z.-L. Zhou Nov 1997

Steps Toward Determination Of The Size And Structure Of The Broad-Line Region In Active Galactic Nuclei. Xi. Intensive Monitoring Of The Ultraviolet Spectrum Of Ngc 7469, I. Wanders, Bradley M. Peterson, D. Alloin, T.R. Ayres, J. Clavel, D. Michael Crenshaw, K. Horne, Gerard A. Kriss, Julian Henry Krolik, Matthew A. Malkan, Hagai Netzer, Paul T. O'Brien, G.A. Reichert, P.M. Rodriguez-Pascual, W. Wamsteker, T. Alexander, K. S.J. Anderson, E. Benitez, N.G. Bochkarev, A.N. Burenkov, F.-Z. Cheng, S.J. Collier, A. Comastri, M. Dietrich, D. Dultzin-Hacyan, B.R. Espey, A. V. Filippenko, C. Martin Gaskell, I.M. George, M.R. Goad, L.C. Ho, Shai Kaspi, W. Kollatschny, Kirk T. Korista, Ari Laor, G.M. Macalpine, M. Mignoli, S.L. Morris, K. Nandra, S. Penton, Richard William Pogge, R.L. Ptak, J.M. Rodriguez-Espinoza, M. Santos-Lleo, A.I. Shapovalova, J.M. Shull, Stephanie A. Snedden, L.S. Sparke, G.M. Stirpe, W.-H. Sun, T.J. Turner, M.-H. Ulrich, T.-G. Wang, C. Wei, W.F. Welsh, S.-J. Xue, Z.-L. Zhou

C. Martin Gaskell Publications

From 1996 June 10 to July 29, the International Ultraviolet Explorer monitored the Seyfert 1 galaxy NGC 7469 continuously in an attempt to measure time delays between the continuum and emission-line fluxes. From the time delays, one can estimate the size of the region dominating the production of the UV emission lines in this source. We find the strong UV emission lines to respond to continuum variations with time delays of about 2.d3-3.d1 for Lyα, 2.d7 for C IV λ1549, 1.d9-2.d4 for N IV λ …

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A Situational Pedagogy For Elementary Mathematics, Vincent Haag Nov 1997

A Situational Pedagogy For Elementary Mathematics, Vincent Haag

Humanistic Mathematics Network Journal

No abstract provided.

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The Object And The Study Of Mathematics, Pinar Karaca Nov 1997

The Object And The Study Of Mathematics, Pinar Karaca

Humanistic Mathematics Network Journal

No abstract provided.

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Book Review: Ethnomathematics--Challenging Eurocentrism Inmathematics Education, Edited Byarthur B. Powell And Marilyn Frankenstein, Karen Dee Michalowicz Nov 1997

Book Review: Ethnomathematics--Challenging Eurocentrism Inmathematics Education, Edited Byarthur B. Powell And Marilyn Frankenstein, Karen Dee Michalowicz

Humanistic Mathematics Network Journal

No abstract provided.

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Teaching College Physics To A Blind Student, Michelle Parry, Mark Brazier, Ephraim Fischbach Nov 1997

Teaching College Physics To A Blind Student, Michelle Parry, Mark Brazier, Ephraim Fischbach

Chemistry & Physics Faculty Publications

No abstract provided.

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Strawberry Valley Assessment, A Cooperative Project Between The Mitigation Commission & The U.S. Forest Service, Mitigation Commission, U.S. Forest Service Nov 1997

Strawberry Valley Assessment, A Cooperative Project Between The Mitigation Commission & The U.S. Forest Service, Mitigation Commission, U.S. Forest Service

All U.S. Government Documents (Utah Regional Depository)

No abstract provided.

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