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Articles 21811 - 21840 of 21971

Full-Text Articles in Physical Sciences and Mathematics

A Survey Of Water Flow In Drainage Ditches And Streams In South Central Minnesota, Clay L. Pierce, Bill Thompson Jan 1981

A Survey Of Water Flow In Drainage Ditches And Streams In South Central Minnesota, Clay L. Pierce, Bill Thompson

Clay L. Pierce

Discharge was monitored on 13 agricultural drainage ditches and 4 small rivers in south central Minnesota. Derived data were categorized by response to hydrologic events and stream order. Stream order was found to be the most reliable predictor of hydrologic event response. Peak flows in drainage ditches were found to correspond to peak flows in rivers.

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Expansion Approach To Photodissociation Dynamics. I. Theory, Kazuo Takatsuka, Mark S. Gordon Jan 1981

Expansion Approach To Photodissociation Dynamics. I. Theory, Kazuo Takatsuka, Mark S. Gordon

Mark S. Gordon

We propose a new formulation for a photodissociation process to which an expansional (or algebraic) quantum‐variation‐method of scattering is applicable. By solving a ’’full collision’’ problem which describes a multichannel process on the repulsive surface, the photodissociation scheme takes account of interchannel coupling from the outset. Our expression for the amplitude of the partial linewidth is similar to that of the ’’half‐collision’’ approximation of Jortner e t a l. The present formalism differs in that the scattering wave functions take acount of interchannel coupling exactly. As a result, only on‐the‐energy‐shell contributions appear in the partial linewidth.

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Expansion Approach To Photodissociation Dynamics. Ii. Correction Formula For Linewidth And Numerical Examples For Hcn, Kazuo Takatsuka, Mark S. Gordon Jan 1981

Expansion Approach To Photodissociation Dynamics. Ii. Correction Formula For Linewidth And Numerical Examples For Hcn, Kazuo Takatsuka, Mark S. Gordon

Mark S. Gordon

A correction formula for energy disposal and linewidth of photodissociation dynamics is proposed. This formula was derived from an identity similar to the Kato identity of the scattering theory. Thanks to the correction formula the resultant linewidth turns out to be more accurate and stable even when a relatively poor basis set is used. Numerical examples for assumed direct dissociation of HCN, DCN, and TCN and for the predissociation of HCN and DCN are presented.

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Centers Of Polymer Research; Polymer Science In Kyoto, Japan, Otto Vogl, A. Nakajima Jan 1981

Centers Of Polymer Research; Polymer Science In Kyoto, Japan, Otto Vogl, A. Nakajima

Otto Vogl

No abstract provided.

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Synoptic Climatology Of The Western United States In Relation To Climatic Fluctuations During The Twentieth Century, R. G. Barry, G. Kiladis, Raymond S. Bradley Jan 1981

Synoptic Climatology Of The Western United States In Relation To Climatic Fluctuations During The Twentieth Century, R. G. Barry, G. Kiladis, Raymond S. Bradley

Raymond S Bradley

An objectively derived catalogue of daily pressure patterns for 11199-1974 has been prepared for the western United States. The temperature and precipitation characteristics of the major types are described and a more detailed analysis for Colorado in extreme cold and warm months shows that the sign of the anomalies for each type is generally consistent with expectation hased Oil the prohable airflow patterns. A regression analysis of type frequencies versus temperature and precipitation anomalies for 1899--1970 at stations east and west of the Continental Divide in the Rocky Mountain states shows that useful explanation of variance is obtained only for …

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Structure-Factor Measurements In 4he At Saturated Vapor Pressure For 1.38<~T<~4.24 K, Robert Hallock, H. N. Robkoff Jan 1981

Structure-Factor Measurements In 4he At Saturated Vapor Pressure For 1.38<~T<~4.24 K, Robert Hallock, H. N. Robkoff

Robert Hallock

We present the results of measurements of the liquid structure factor, S(k), for liquid 4He at saturated vapor pressure at seven temperatures between 1.38 and 4.24 K over the momentum-transfer range k<~5.1 Å-1. The results are compared with previous measurements carried out by both x-ray and neutron scattering techniques. Comparison with recent theoretical work emphasizes the importance of higher-order correlations and more realistic potentials in the description of the liquid. Measurements in the vicinity of the λ transition document a loss in spatial order as the liquid is cooled through Tλ.

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Phase Separation In 3he-4he Mixture Films, Robert Hallock, F. M. Ellis, M. D. Miller, R. A. Guyer Jan 1981

Phase Separation In 3he-4he Mixture Films, Robert Hallock, F. M. Ellis, M. D. Miller, R. A. Guyer

Robert Hallock

We report detailed observations of the propagation of third sound in 3He-4He mixture films as a function of temperature and 3He concentration. The data are consistent with a simple model for the film and we conclude that thin 3He-4He mixture films exhibit nearly complete phase separation.

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Areal Distribution, Thickness, Mass, Volume, And Grain Size Of Air-Fall Ash From The Six Major Eruptions Of 1980, Andrei M. Sarna-Wojcicki, Susan Shipley, Richard B. Waitt Jr., Daniel Dzurisin, Spencer H. Wood Jan 1981

Areal Distribution, Thickness, Mass, Volume, And Grain Size Of Air-Fall Ash From The Six Major Eruptions Of 1980, Andrei M. Sarna-Wojcicki, Susan Shipley, Richard B. Waitt Jr., Daniel Dzurisin, Spencer H. Wood

Spencer H. Wood

The airborne-ash plume front from the Mount St. Helens eruption of May 18 advanced rapidly to the northeast at an average velocity of about 250 km/hr during the first 13 min after eruption. It then traveled to the east-northeast within a high-velocity wind layer at altitudes of 10-13 km at an average velocity of about 100 km/hr over the first 1,000 km. Beyond about 60 km, the thickest ash fall was east of the volcano in Washington, northern Idaho, and western Montana. A distal thickness maximum near Ritzville, Wash., is due to a combination of factors: (1) crude sorting within …

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Effects Of N2h4 On The Transition Temperature In The Anisotropic Superconductor Tase3, K. Yamaya, T. H. Geballe, Juana Vivó Acrivos, J. Code Jan 1981

Effects Of N2h4 On The Transition Temperature In The Anisotropic Superconductor Tase3, K. Yamaya, T. H. Geballe, Juana Vivó Acrivos, J. Code

Juana Vivó Acrivos

No abstract provided.

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Mott G-Ratios In Rbx(Nh3)1-X And Oxidation State Of Rubidium Compounds From Xas, Juana Vivó Acrivos, K. Hathaway, A. Robertson, M. P. Klein, A. Thompson Jan 1981

Mott G-Ratios In Rbx(Nh3)1-X And Oxidation State Of Rubidium Compounds From Xas, Juana Vivó Acrivos, K. Hathaway, A. Robertson, M. P. Klein, A. Thompson

Juana Vivó Acrivos

The x-ray absorption spectra (XAS) of Rb metal, Rh,("JH,J, ,, 2H-NbSe2Rb111x and RbBr near the Rb K-edge have been used to ascertain that the oxidation state V of rubidium dissolved in ammonia and intt:rcalated in the layer compound is in the range 0 < V < I. Theobservededge shifts with temperature for semimctals are explainedin terms of the population of band states, and the ratio of the density states near the mobility edge over that calculated for a free electron model, i.e. the Mott ratio g, is ascertained using a semiempirical relation developed for the x-ray absorbance from Is levels to empty states ncar the mobility edge.

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Conduction Band Symmetry In Ta Chalcogenides From Ta L Edge X-Ray Absorption Spectroscopy (Xas), Juana Vivó Acrivos, S.S. P. Parkin, J. Code, J. Reynolds, K. Hathaway, H. Kurasaki, E. Marseglia Jan 1981

Conduction Band Symmetry In Ta Chalcogenides From Ta L Edge X-Ray Absorption Spectroscopy (Xas), Juana Vivó Acrivos, S.S. P. Parkin, J. Code, J. Reynolds, K. Hathaway, H. Kurasaki, E. Marseglia

Juana Vivó Acrivos

No abstract provided.

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A Quantitative Test Of Unimolecular Rate Theory In The Multi‐Photon Dissociation Of Cf2Cfcl, John C. Stephenson, Stephen E. Bialkowski, David S. King, Everet Thiele, James Stone, Myron F. Goodman Jan 1981

A Quantitative Test Of Unimolecular Rate Theory In The Multi‐Photon Dissociation Of Cf2Cfcl, John C. Stephenson, Stephen E. Bialkowski, David S. King, Everet Thiele, James Stone, Myron F. Goodman

Stephen E. Bialkowski

We have measured the distribution of total energy in reaction products for the CO2 laser‐induced MPD: CF2CFCl→CF2+CFC1. From a separate study of MPD rates as a function of laser intensity and inert buffer gas pressure, reliable estimates of the radiative pumping rates are known for this reaction. These results, when analyzed together, allow us to extract a unimolecular A factor from the MPD data. The determined value A = 3×1016 sec−1 agrees well with estimates based on independent thermal data.

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F-Region East-Westdrifts At Jicamarca, Bela G. Fejer, D. T. Farley, C. A. Gonzales, R. F. Woodman, C. Calderson Jan 1981

F-Region East-Westdrifts At Jicamarca, Bela G. Fejer, D. T. Farley, C. A. Gonzales, R. F. Woodman, C. Calderson

Bela G. Fejer

F region east-west drifts have been measured at Jicamarca for almost 10 years, using incoherent scatter. The drifts are westward during the day and eastward at night. The daytime drift velocities are about 50 m/s and change very little with season or solar cycle. The evening reversal occurs at about 1600 local time throughout the solar cycle. The maximum nighttime eastward drifts are about 105 and 130 m/s during solar minimum and maximum, respectively. The daytime and nighttime drifts show very litle variation with magnetic activity. These Jicamarca incoherent scatter results (especially the reversal times) differ appreciably from results obtained …

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Triple Gamma Directional Correlations In The Decay Of Europium-154, Gary Lewis Dec 1980

Triple Gamma Directional Correlations In The Decay Of Europium-154, Gary Lewis

Gary C. Lewis

The ('154)Eu nucleus decays by beta emission to an excited state of the ('154)Gd nucleus. The resulting ('154)Gd nucleus decays to its ground state by emission of gamma rays. One series of gamma rays emitted in this process is a cascade of energies 723 keV, 873 keV, and 123 keV. The 873 keV gamma ray is a mixture of E2 and M1 radiation. The mixing ratio of this transition has been measured using the triple gamma directional correlation technique. The experiments used a planar geometry with one angle fixed at 90 degrees. Two Ge(Li) detectors and one NaI(T1) detector were …

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An Oscillation Condition For Differential Equations Of Arbitrary Order, William F. Trench Dec 1980

An Oscillation Condition For Differential Equations Of Arbitrary Order, William F. Trench

William F. Trench

No abstract provided.

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Limits Of Certain Sequences Associated With Cylinder Functions, William F. Trench Dec 1980

Limits Of Certain Sequences Associated With Cylinder Functions, William F. Trench

William F. Trench

No abstract provided.

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The Dependence On Zenith Angle Of The Strength Of 3-Meter Equatorial Electrojet Irregularities, H. M. Ierkic, Bela G. Fejer, D. T. Farley Dec 1980

The Dependence On Zenith Angle Of The Strength Of 3-Meter Equatorial Electrojet Irregularities, H. M. Ierkic, Bela G. Fejer, D. T. Farley

Bela G. Fejer

Radar measurements in Peru were used to deduce the zenith angle dependence of the scattering cross section of plasma irregularities generated by instabilities in the equatorial electrojet. The irregularities probed by the 50 MHz Jicamarca radar had a wavelength of 3m. The cross section for the type 2 irregularities was isotropic in the plane perpendicular to the magnetic field, while the cross section for the stronger type 1 irregularities varied with zenith angle at a rate of approximately 0.3 dB/degree; the horizontally traveling waves were more than 100 times stronger than those traveling vertically.

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Ring Strain In Cyclopropane, Cyclopropene, Silacyclopropane, And Silacyclopropene, Mark S. Gordon Dec 1980

Ring Strain In Cyclopropane, Cyclopropene, Silacyclopropane, And Silacyclopropene, Mark S. Gordon

Mark S. Gordon

The strain energy in four three-membered rings is calculated by using the appropriate isodesmic reactions. Calculations with and without d functions on the heavy atoms indicate that while these polarization functions tend to reduce ring strain, the addition of d orbitals has little effect on the predicted trends. While introduciton of unsaturation drastically increases the strain in the carbon system (cyclopropane---. cyclopropene), this is not the case for silicon (silacyclopropane--+ silacyclopropene). As a result cyclopropane and cyclopropene are predicted to be the least and most strained rings, respectively.

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Centers Of Polymer Research; Polymer Science In Silesia, Poland:Gliwice, Zabrze, Otto Vogl, W. Pradellok Dec 1980

Centers Of Polymer Research; Polymer Science In Silesia, Poland:Gliwice, Zabrze, Otto Vogl, W. Pradellok

Otto Vogl

No abstract provided.

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Polymer Science In Lodz, Poland, Otto Vogl, P. Kubisa Nov 1980

Polymer Science In Lodz, Poland, Otto Vogl, P. Kubisa

Otto Vogl

No abstract provided.

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Synthesis Of Peroxyacetyl And Peroxyaroyl Nitrates. Complexation Of Perqxyacetyl Nitrate With Benzene, Tina M. Kravetz, Steve W. Martin, G. David Mendenhall Oct 1980

Synthesis Of Peroxyacetyl And Peroxyaroyl Nitrates. Complexation Of Perqxyacetyl Nitrate With Benzene, Tina M. Kravetz, Steve W. Martin, G. David Mendenhall

Steve W. Martin

Convenient procedures are given for the condensed-phase synthesis Of peroxyacetyl nitrate (PAN), peroxybenzoyl ni- sponding peracid% sulfuric acid, and sodium nitrate- The compounds of considerable interest because of their physio- logical and action in polluted atmospheres (1-4). Samples of such compounds are routinely needed for cali- several syntheses have been published (I, 5-8). The procedure of Louw et al. (5) is particularly convenient because the re- corrosive reagents are required. trate, and m-chloroperoxybenzoyl nitrate from the corre- position of the ‘H NMR signal from peroxyacetyl nitrate in CC14-benzene mixtures depended on the solvent composition benzene, with K,, = 0.095 at …

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An Empirical Model Of Quiet Dayionospheric Electric Fields Of Middle And Low Latitudes, A. D. Richmond, M. Blanc, B. A. Emery, R. H. Wand, Bela G. Fejer, R. F. Woodland, S. Ganguly, P. Amyenc, R. A. Behnke, C. Calderon, J. V. Evans Sep 1980

An Empirical Model Of Quiet Dayionospheric Electric Fields Of Middle And Low Latitudes, A. D. Richmond, M. Blanc, B. A. Emery, R. H. Wand, Bela G. Fejer, R. F. Woodland, S. Ganguly, P. Amyenc, R. A. Behnke, C. Calderon, J. V. Evans

Bela G. Fejer

Seasonally averaged quiet-day F region ionospheric E × B drift observations from the Millstone Hill, St. Santin, Arecibo, and Jicamarca incoherent scatter radars are used to produce a model of the middle and low-latitude electric field for solar minimum conditions. A function similar to an electrostatic potential is fitted to the data to provide model values continuous in latitude, longitude, time of day, and day of the year. This model is intended to serve as a reference standard for applications requiring global knowledge of the mean electric field or requiring information at some location removed from the observing radars. This …

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Secular Fluctuations Of Temperature In The Rocky Mountain States And A Comparison With Precipitation Fluctuations, Raymond S. Bradley Jul 1980

Secular Fluctuations Of Temperature In The Rocky Mountain States And A Comparison With Precipitation Fluctuations, Raymond S. Bradley

Raymond S Bradley

Fluctuations of temperature in the Rocky Mountain states of Idaho. Montana. Wyoming. Colorado and Utah are analyzed forthe period 1891-1978. Prior to 1891. data forthis area are too sparse to make meaningful generalizations. After screening temperature data for homogeneity. selected records are used to map seasonal mean temperature departures from 1941-70 means. In all seasons. mean temperatures were higher by 1-I.soC during the last 40 years compared to the previous 40-50 years. However. spring and fall temperatures have been declining since the period maximum in the late 1930·s. Pentad mean winter and summer temperatures show a statistically significant temperature increase …

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Ionospheric Irregularities, Bela G. Fejer, M. C. Kelley Jun 1980

Ionospheric Irregularities, Bela G. Fejer, M. C. Kelley

Bela G. Fejer

Extensive experimental and theoretical research has been performed in the last decade to study ionospheric irregularities. These studies have shown that plasma instabilities play a major role in the generation of the irregularities. In this work we describe in detail the recent experimental studies of the E and F region irregularities and also the extensive work on plasma instability theories developed to explain them. We also describe both radio wave and spacecraft-borne experimental techniques to allow a common ground for the understanding of the data from ground-based and in situ experiments. To date, theoretical work has been mostly concentrated on …

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Fluid-Structure-Factor Measurements In 4he For 5.5<=T<=7.0 K, Robert Hallock, D. A. Ewen, H. N. Robkoff May 1980

Fluid-Structure-Factor Measurements In 4he For 5.5<=T<=7.0 K, Robert Hallock, D. A. Ewen, H. N. Robkoff

Robert Hallock

We report precise measurements of the structure factor S(k) as a function of the momentum transfer k for 4He at T=5.5 and 6.5 K in the density range 10<~ρ<~155 kg/m3. No theoretical predictions that can be tested against the data are available. The recent theoretical work by Bruch et al. at T=7.0 K, ρ=69.6 kg/m3 is in only limited agreement with our experimental data at T=7.0 K, ρ=69.0 kg/m3.

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Third Sound And The Decay Of Persistent Currents In Unsaturated 3he-4he Films, Robert Hallock May 1980

Third Sound And The Decay Of Persistent Currents In Unsaturated 3he-4he Films, Robert Hallock

Robert Hallock

We report the observation of metastable currents in unsaturated 3He-4He-mixture films. The decay rate of these currents is found to be an increasing function of 3He concentration in the film. A simple model for the role of the 3He, adequate to explain our observations of the concentration dependence of the third-sound velocity, does not agree with the measured decay rates.

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Ozonation At The Stander Water Reclamation Plant, Johannes Van Leeuwen, J. Prinsloo Apr 1980

Ozonation At The Stander Water Reclamation Plant, Johannes Van Leeuwen, J. Prinsloo

Johannes van Leeuwen

The results achieved by ozonation at the Stander Water Reclamation Plant, Pretoria, are discussed. A packed column together with an injector mixing device gave ozone· utilization levels higher than 95 % at dosages of about 10 mg/ dm3. Redistribution plates in the packing proved necessary to prevent poor adsorption due to backmixing in the gas phase. Disinfection is satisfactory if total oxidant residuals can be maintained at more than 0,2 mg/dm3 for 15 min. The results indicated that ozonation also lowered the chemical oxygen demand and total organic carbon concentration in the water. In spite of the fact that it …

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The Electrochemical Reduction Of Phenylpropadiene, Dennis Peters, Tsu-Yu Chen, Mark Anderson, Steven Grossman Feb 1980

The Electrochemical Reduction Of Phenylpropadiene, Dennis Peters, Tsu-Yu Chen, Mark Anderson, Steven Grossman

Mark R. Anderson

No abstract is currently available.

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The Effects On Grain-Boundary Processes Of The Steps In The Boundary Plane Associated With The Cores Of Grain-Boundary Dislocations, Alexander H. King, D. A. Smith Jan 1980

The Effects On Grain-Boundary Processes Of The Steps In The Boundary Plane Associated With The Cores Of Grain-Boundary Dislocations, Alexander H. King, D. A. Smith

Alexander H. King

The contribution of the associated steps to the properties of grain-boundary dislocations are investigated. Two methods of step-height determination are given and it is shown that the step height, like the Burgers vector, must be conserved during the reactions of grain-boundary dislocations: this is not always automatic and additional coherent steps must take part in some reactions. The energies associated with steps have been estimated and compared with the elastic energies of grain-boundary dislocations; these comparisons suggest that (a) the reduction of elastic energy alone may not be a sufficient criterion for the progress of a reaction and (b) that …

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Thermodynamic Model And Sum Rules For Three-Phase Coexistence Near Thetricritical Point In A Liquid Mixture, Miron Kaufman, K. K. Bardhan, Robert B. Griffiths Jan 1980

Thermodynamic Model And Sum Rules For Three-Phase Coexistence Near Thetricritical Point In A Liquid Mixture, Miron Kaufman, K. K. Bardhan, Robert B. Griffiths

Miron Kaufman

Two sum rules for order-parameter susceptibilities are derived for the classical theory of the three-phase region near a tricritical point in ordinary liquid mixtures. The classical theory can also be fitted in a quantitative way to the composition data of Lang and Widom near the tricritical point in the mixture ethanol+ benzene+ water + ammonium sulfate.

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