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A New Search For Interstellar C3, Charles L. Joseph, Theodore P. Snow, C Gregory Seab Jan 1988

A New Search For Interstellar C3, Charles L. Joseph, Theodore P. Snow, C Gregory Seab

Physics Faculty Publications

A new, very sensitive search for interstellar triatomic carbon has resulted in upper limits for a few diffuse clouds of order 1010 cm – 2, or about 10 – 11 with respect to hydrogen. These limits are consistent with recent cold diffuse cloud chemistry models, but may be in conflict with shocked cloud models such as those invoked to explain CH + abundances. Our results may also be argue against linear carbon-chain molecules as carriers of the diffuse interstellar bands.

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Discharge Suppression System For A Double Focusing, Atmospheric Pressure Ionization Mass Spectrometer, Andrew H. Grange, Robert J. O'Brien, Douglas F. Barofsky Jan 1988

Discharge Suppression System For A Double Focusing, Atmospheric Pressure Ionization Mass Spectrometer, Andrew H. Grange, Robert J. O'Brien, Douglas F. Barofsky

Chemistry Faculty Publications and Presentations

An electrical discharge suppression system for a medium throughput (∼2 l/s) pumping line has been devised that works up to potentials of ±15 kV. This device permits atmospheric pressure ionization sources to be interfaced to high-resolution, magnetic sector mass spectrometers with source potentials of 6-10 kV

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Measurements Of The Drag On Spheres Falling Through The Air, J. G. Ross, Stephen R. Addison, N.O (Jack) Gaiser Jan 1988

Measurements Of The Drag On Spheres Falling Through The Air, J. G. Ross, Stephen R. Addison, N.O (Jack) Gaiser

Journal of the Arkansas Academy of Science

No abstract provided.

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Magnetite And Magnetotaxis In Microorganisms, Richard B. Frankel, R. P. Blakemore Jan 1988

Magnetite And Magnetotaxis In Microorganisms, Richard B. Frankel, R. P. Blakemore

Physics

No abstract provided.

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Solution Manual Of University Physics: Mechanics, Yimin Wang, Clifton Keller Jan 1988

Solution Manual Of University Physics: Mechanics, Yimin Wang, Clifton Keller

All Books

No abstract provided.

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Preparation, Crystal Structure, And Physical Properties Of A Pyrogallol-Bridged Vanadium(Iii) Complex, Seunghee Lee, Koji Nakanishi, Michael Y. Chiang, Richard B. Frankel, K. Spartalian Jan 1988

Preparation, Crystal Structure, And Physical Properties Of A Pyrogallol-Bridged Vanadium(Iii) Complex, Seunghee Lee, Koji Nakanishi, Michael Y. Chiang, Richard B. Frankel, K. Spartalian

Physics

The structure, n.m.r. spectrum, and magnetic properties of the vanadium(III) dimer [(acac)4V2{µ-OC6H3(OH)2}2] formed from [VO(acac)2] and an excess of pyrogallol are described.

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The Energy-Dependence Of Polarization Observables In The ²H(D,Γ)⁴He Reaction, H. R. Weller, R. M. Whitton, J. Langenbrunner, Evans Hayward, W. R. Dodge, S. Kuhn, D. R. Tilley Jan 1988

The Energy-Dependence Of Polarization Observables In The ²H(D,Γ)⁴He Reaction, H. R. Weller, R. M. Whitton, J. Langenbrunner, Evans Hayward, W. R. Dodge, S. Kuhn, D. R. Tilley

Physics Faculty Publications

Measurements of the tensor and vector analyzing powers, Ayy(130°) and Ay(130°), have been obtained for the 2H(d,γ )4He reaction for energies ranging from Ed(lab) = 0.3 MeV to Ed(lab) = 50 MeV. The Ayy(130°) data are sensitive to the D-state present in the ground state of 4He and are observed to have their maximum value near Ed = 30 MeV. The vector analyzing power data show a maximum near Ed = 3 MeV. The data are compared to the results of a microscopic …

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Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs Jan 1988

Condensation Method For Humidity Measurement In The Umr Cloud Simulation Chamber., Donald E. Hagen, Daniel R. White, Darryl J. Alofs

Mechanical and Aerospace Engineering Faculty Research & Creative Works

A Cloud Simulation Facility Has Been Developed for the Study of Various Atmospheric Cloud Processes. the Initial Relative Humidity of the Air Sample Put into the Cloud Chamber is a Key Parameter in Virtually Any Experiment and Needs to Be Known Accurately. This Report Describes How the Cloud Simulation Chamber itself Has Been Used as a Condensation Type Hygrometer to Calibrate the System's Humidifier. Two Distinct and Physically Different Methods for Inferring Mixing Ratio Are Used, One Exploiting the Sensitivity of Aerosol Activation to Humidity, and the Other Exploiting the Sensitivity of the Rate of Growth of Cloud Droplets to …

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Aerosol Evolution And Metamorphosis During And After Haze (Fog) Formation Over The Bay Of Naples, Josef Podzimek, H. Andriambeloma, A. De Maio, M. Ianniruberto, R. Montmory, E. Sansone, G. Spezie, G. Stowell Jan 1988

Aerosol Evolution And Metamorphosis During And After Haze (Fog) Formation Over The Bay Of Naples, Josef Podzimek, H. Andriambeloma, A. De Maio, M. Ianniruberto, R. Montmory, E. Sansone, G. Spezie, G. Stowell

Physics Faculty Research & Creative Works

No abstract provided.

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Charge- And Angle-Correlated Inelasticities In Collisions Of Bare Fast Carbon Ions With Neon, R. Schuch, H. Schöne, P. D. Miller, H. F. Krause, P. F. Dittner, S. Datz, Ronald E. Olson Jan 1988

Charge- And Angle-Correlated Inelasticities In Collisions Of Bare Fast Carbon Ions With Neon, R. Schuch, H. Schöne, P. D. Miller, H. F. Krause, P. F. Dittner, S. Datz, Ronald E. Olson

Physics Faculty Research & Creative Works

We have studied the detailed energy balance in collisions of 10-MeV C6+ ions with Ne. In these collisions, the Ne is multiply ionized and the C ion may emerge as either C6+ or C5+. Projectile energy loss and scattering angle for a given carbon-ion charge state were determined in a high-resolution magnetic spectrograph and were measured in coincidence with the formation of a given Ne recoil-ion charge state. The amount of energy transferred to the continuum electrons exceeds, by far, the sum of the values of the ionization potentials. © 1988 The American Physical Society.

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Dynamics Of Antimatter-Atom Collisions, Ronald E. Olson, Timothy James Gay Jan 1988

Dynamics Of Antimatter-Atom Collisions, Ronald E. Olson, Timothy James Gay

Physics Faculty Research & Creative Works

Classical-trajectory Monte Carlo calculations have been used to study ionizing collisions between charged particles (p,p»,e+,e-) and He atoms at an incident velocity of 2.83 a.u. While differences in the total single-ionization cross sections for these projectiles are small, our calculations reveal large effects at all angles in the ionized electron spectra and provide qualitative evidence for a Barkas effect in p and p» collisions. Experimental data agree well with our fully classical calculations, including cross sections involving ejected electrons of long wavelength. © 1988 The American Physical Society.

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Argon Metastable-Cadmium Dihalide Energy Transfer Collisions In A Flowing Afterglow, Christopher L. Bohler, Laird D. Schearer Jan 1988

Argon Metastable-Cadmium Dihalide Energy Transfer Collisions In A Flowing Afterglow, Christopher L. Bohler, Laird D. Schearer

Physics Faculty Research & Creative Works

The energy dependence of dissociating collisions between argon metastable atoms and cadmium dihalide molecules have been studied in a flowing afterglow apparatus. The fluorescence spectra obtained in the range of 3000-7600 Å which result from the Ar(3P2) + CdX2 interactions indicate a dominant dissociative excitation production mechanism. The emission spectra are used to narrow the uncertainty in the currently accepted values for the dissociation energy of the CdX2 molecules. The Wigner spin rule (conservation of total electronic spin) was verified for these processes as shown by the dominance of final state triplet production as compared to the virtual absence of …

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Electron Loss From Helium Atoms By Collisions With Fully Stripped Ions, A. E. Wetmore, Ronald E. Olson Jan 1988

Electron Loss From Helium Atoms By Collisions With Fully Stripped Ions, A. E. Wetmore, Ronald E. Olson

Physics Faculty Research & Creative Works

Electron-loss cross sections have been calculated for fully stripped ions with charge states +1 to +100 colliding with helium atoms in the energy range 100 1000 kev/amu. The classical-trajectory Monte Carlo method was used along with a model of the helium atom with two active electrons. The reactions studied were single and double ionization, single- and double-electron capture, and electron capture plus ionization. Cross sections for the single-electron-removal reactions agree well with experimental data. Double-electron-removal cross sections are in qualitative agreement with experimental results. The n-level distributions following electron capture show that the electron-capture plus ionization and double electron-capture processes …

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Contribution Of Excited Hydrogen Atoms To Charge-Exchange Excitation Of Impurities In Fusion Plasmas, R. C. Isler, Ronald E. Olson Jan 1988

Contribution Of Excited Hydrogen Atoms To Charge-Exchange Excitation Of Impurities In Fusion Plasmas, R. C. Isler, Ronald E. Olson

Physics Faculty Research & Creative Works

Cross sections are calculated for charge transfer into excited states of C5+ and O7+ from collisions of C6+ and O8+ with hydrogen atoms in the n=2 and 3 levels. Effective emission cross sections that account for cascading is then derived for spectral lines emitted when the product ions decay. These are compared to the emission cross sections calculated for excitation by ground-state hydrogen. It is shown that in some circumstances the contribution from excited hydrogen atoms must be taken into account when visible lines are used to determine the oxygen or carbon density from charge-exchange spectroscopy …

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A Study Of Vapor Phase Self-Initiated Thermal Polymerization Of Styrene With An Expansion Chamber, John L. Schmitt Jan 1988

A Study Of Vapor Phase Self-Initiated Thermal Polymerization Of Styrene With An Expansion Chamber, John L. Schmitt

Physics Faculty Research & Creative Works

Studies of the self-initiated polymerization of styrene have been performed in the uniform environment of an expansion cloud chamber, using nucleation of liquid monomer drops for detection. These studies are the first of this kind in an expansion chamber and, although preliminary and designed to explore feasibility, have yielded many interesting results. The occurrence of the self-initiated nonterminated gas phase processes, previously observed in a diffusion cloud chamber, has now been confirmed in an expansion chamber. At 15 °C the initiation rate is measured to be 2 to 6 radicals cm-3 s-1 and the propagation constant is approximately 6X10-21 cm3 …

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Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy James Gay, Jimmie Garwin Edwards, Edward Boyd Hale, M. L. Mckenzie, Ronald E. Olson Jan 1988

Projectile-Charge Dependence Of Ejected-Electron Spectra, V. D. Irby, Timothy James Gay, Jimmie Garwin Edwards, Edward Boyd Hale, M. L. Mckenzie, Ronald E. Olson

Physics Faculty Research & Creative Works

We have studied H++He and He++3+He ionizing collisions at intermediate energies (60 to 120 keV/amu) and have observed a significant shift in the velocity position of the maxima in forward-ejected electron spectra when changing projectiles from protons to particles. In ionizing collisions, a large portion of the ejected electrons are stranded near the transitory equiforce, or saddle point, position between the target ion and receding projectile. The shift in the electron spectra maxima to smaller velocities, due to changing projectiles from protons to particles, is consistent with the shift in the saddle-point velocity when the projectile …

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Single-Electron Removal Processes In Collisions Of Positrons And Protons With Helium At Intermediate Velocities, D. R. Schultz, Ronald E. Olson Jan 1988

Single-Electron Removal Processes In Collisions Of Positrons And Protons With Helium At Intermediate Velocities, D. R. Schultz, Ronald E. Olson

Physics Faculty Research & Creative Works

Total cross sections for single ionization and charge transfer have been calculated using the classical-trajectory Monte Carlo (CTMC) technique for collisions of both positrons and protons with helium. Analysis of the classical trajectories has helped to explain the differences in the collision mechanisms responsible for the observed relative magnitudes of the positron and proton electron-removal cross sections. In the intermediate collision velocity range (1.5 a.u.

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An Optically Controlled Closing And Opening Semiconductor Switch, K. H. Schoenbach, V. K. Lakdawala, R. Germer, S. T. Ko Jan 1988

An Optically Controlled Closing And Opening Semiconductor Switch, K. H. Schoenbach, V. K. Lakdawala, R. Germer, S. T. Ko

Electrical & Computer Engineering Faculty Publications

A concept for a bulk semiconductor switch is presented, where the conductivity is increased and reduced, respectively, through illumination with light of different wavelengths. The increase in conductivity is accomplished by electron ionization from deep centers and generation of bound holes. The reduction of conductivity is obtained by hole ionization from the excited centers and subsequent recombination of free electrons and holes. The transient behavior of electron and hole density in a high power semiconductor (GaAs:Cu) switch is computed by means of a rate equation model. Changes in conductivity by five orders of magnitude can be obtained.

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Molecular-Dynamics Simulation Of The Structural Phase Transition In Rb2Cacl4, D. P. Billesbach, P. J. Edwardson, John R. Hardy Jan 1988

Molecular-Dynamics Simulation Of The Structural Phase Transition In Rb2Cacl4, D. P. Billesbach, P. J. Edwardson, John R. Hardy

John R. Hardy Papers

We have simulated the structural phase transition of one member of A2BX4 layered perovskite-like compounds, Rb2CaC14. This family of compounds may be thought of as being constructed from normal perovskite unit cells but with a different stacking arrangement. In recent months, this structural family has become extremely important since it is the parent structure from which the new class of high-temperature superconductors comes from. The simulation was done using ab initio potentials with no adjustable parameters. Our calculations show a specific-heat anomaly at 400 K which corresponds to an observed pseudorotation of the …

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Radiobiological Modeling Based On Track Structure, Robert Katz Jan 1988

Radiobiological Modeling Based On Track Structure, Robert Katz

Robert Katz Publications

Since the interaction of beams of charged particles with targets in physics is customarily based on beam fluence and interaction cross section we have chosen the same logical structure for our radiobiological model.

Proceeding from simple to complex systems we have first constructed and verified a track structure model of observable tracks in nuclear emulsions, then of dry enzymes and viruses, of scintillation counters, of TLD’s, of the Fricke dosimeter as prerequisite to the construction of a valid radiobiological model.

For this model we require 1) knowledge of the average radial distribution of local dose about the path of an …

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Generation Of Moire Contours With Acousto-Optic Cells, Joel H. Blatt, Huey-Chin Chang Ho, Eddie H. Young Jan 1988

Generation Of Moire Contours With Acousto-Optic Cells, Joel H. Blatt, Huey-Chin Chang Ho, Eddie H. Young

Aerospace, Physics, and Space Science Faculty Publications

Moire contours are seen on a curved surface viewed through a grating when the surface is illuminated with a matched grating. We have been able to replace both the projection and viewing physical gratings with gratings of variable spacing generated in acousto-optic cells, and have been able to observe and record Moire contours. The gratings are generated by amplitude modulating 70 MHz AO cells with a 1 to 10 MHz square wave. The gratings become visible on the curved object by strobing the illuminating laser beam with 50 nsec pulses by means of an AO modulator. Data is given showing …

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Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele Jan 1988

Quantum Electrodynamics Based On Self-Fields, Without Second Quantization: A Nonrelativisitc Calculation Of G – 2, A. O. Barut, Jonathan P. Dowling, Jean F. Van Huele

Faculty Publications

Using a formulation of quantum electrodynamics that is not second quantized, but rather based on self-fields, we compute the anomalous magnetic moment of the electron to first order in the fine structure constant α. In the nonrelativistic (NR) case and in the dipole approximation, our result is ae≡(g—2)/2=(4Λ/3m)(α/2π), where Λ is a positive photon energy cutoff and m the electron mass. A reasonable choice of cutoff, Λ/m=¾, yields the correct sign and magnitude for g—2 namely, ae=+α/2π. . In our formulation the sign of a3 is correctly positive, …

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The Effectiveness Of Using Writing In The High School Biology Classroom, Lynne E. Kelly Jan 1988

The Effectiveness Of Using Writing In The High School Biology Classroom, Lynne E. Kelly

Dissertations and Theses @ UNI

"Writing across the curriculum" programs have emerged throughout the United States during the last decade as an attempt to improve both writing skills and learning of today's youth. The purpose of this study was to determine if students learn and retain concepts of biology to a greater extent in a program using expressive writing than a program using traditional expository writing. The sample consisted of two high school biology classes from Fort Dodge Senior High School, Fort Dodge, Iowa. Expressive writing assignments were incorporated into the biology curriculum of the experimental group two to four times a week during the …

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State-Selective Studies Of T→R, V Energy Transfer: The H+Co System, G. K. Chawla, George C. Mcbane, P. L. Houston, G. C. Schatz Dec 1987

State-Selective Studies Of T→R, V Energy Transfer: The H+Co System, G. K. Chawla, George C. Mcbane, P. L. Houston, G. C. Schatz

Peer Reviewed Articles

Collisional energy transfer from H atoms to CO(v=0, J≈2) has been studied at a collision energy of 1.58±0.07 eV by photolyzing H2S at 222 nm in a nozzle expansion with CO and probing the CO(v", J") levels using tunable VUV laser-induced fluorescence. The ratio CO(v"=1)/CO(v"=0) is found to be 0.1±0.008. The rotational distribution of CO(v"=0) peaks at J"gradually; population is still observed at J">45. The rotational distribution of CO(v"=1) is broad and peaks near J"=20. The experimental results are compared to …

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Theory Of The Observations Made Of High-Order Rainbows From A Single Water Droplet, James A. Lock Dec 1987

Theory Of The Observations Made Of High-Order Rainbows From A Single Water Droplet, James A. Lock

Physics Faculty Publications

Over a dozen rainbows have been observed in a single water droplet. They appear as glare spots on the water droplet which take on coloration at the appropriate rainbow angles. The appearance of rainbows as colored glare spots in this situation is understood in terms of the caustics created in the vicinity of the droplet by the refracting light rays. The angular positions of the glare spots are understood in terms of the Fourier transform of the geometric scattering amplitude. The rainbow glare spots are also found to appear numerically in the Fourier transform of the Mie scattered fields. An …

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Evidence For Weak Link And Anisotropy Limitations On The Transport Critical Current In Bulk Polycrystalline Y1Ba2Cu3O Χ , J.W. Ekin, A.I. Braginski, A.J. Panson, M.A. Janocko, D.W. Capone Ii, N.J. Zaluzec, B. Flandermeyer, O.F. De Lima, M. Hong, J. Kwo, Sy_Hwang Liou Dec 1987

Evidence For Weak Link And Anisotropy Limitations On The Transport Critical Current In Bulk Polycrystalline Y1Ba2Cu3O Χ , J.W. Ekin, A.I. Braginski, A.J. Panson, M.A. Janocko, D.W. Capone Ii, N.J. Zaluzec, B. Flandermeyer, O.F. De Lima, M. Hong, J. Kwo, Sy_Hwang Liou

Sy-Hwang Liou Publications

Measurements of the transport critical-current density (Jc), magnetization Jc, and magnetoresistance in a number of bulk sintered samples of Y1Ba2Cu3O χ from several different laboratories indicate that the transport Jc is limited by weak-link regions between high Jc regions. The weak-link Jc has a Josephson character, decreasing by two orders of magnitude as the magnetic field is increased from 0.1 to 10 mT at 77 K. An examination of the grain-boundary region in Y1Ba2Cu3O χ shows no observable impurities or …

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Generating Problem Sets With Word Processing Software, Jearl D. Walker Dec 1987

Generating Problem Sets With Word Processing Software, Jearl D. Walker

Physics Faculty Publications

No abstract provided.

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The O-O Collision Cross-Section: Can It Be Inferred From Aeronomical Measurements?, R G. Burnside, C A. Tipley, Vincent B. Wickwar Dec 1987

The O-O Collision Cross-Section: Can It Be Inferred From Aeronomical Measurements?, R G. Burnside, C A. Tipley, Vincent B. Wickwar

All Physics Faculty Publications

No abstract provided.

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Electrooptic And Piezoelectric Measurements In Photorefractive Barium Titanate And Strontium Barium Niobate, Stephen Ducharme, Jack Feinberg, R.R. Neurgaonkar Dec 1987

Electrooptic And Piezoelectric Measurements In Photorefractive Barium Titanate And Strontium Barium Niobate, Stephen Ducharme, Jack Feinberg, R.R. Neurgaonkar

Stephen Ducharme Publications

We have measured the low-frequency ("unclamped") electrooptic and piezoelectric coefficients in undoped BaTiO3and SrxBa1-xNb2O6 (x = 0.61) crystals using interferometric techniques. The contribution of the piezoelectric effect to the Pockels measurements is discussed. For an applied ac electric field in the range 0.1-200 V/cm, the electrooptic and piezoelectric effects are linear in the magnitude of the applied field and independent of its frequency in the range 10 Hz-100 kHz. The unclamped electrooptic coefficients of poled BaTiO3 single crystals are r13= 19.5 pm ±1 pm/V and r33 = …

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Moment Analysis Of The Cluster-Size-Distribution Approach To Scaling During Coagulation, Thomas W. Taylor, C. M. Sorensen Dec 1987

Moment Analysis Of The Cluster-Size-Distribution Approach To Scaling During Coagulation, Thomas W. Taylor, C. M. Sorensen

Physics Faculty Publications

We study the temporal approach of a cluster size distribution to its asymptotic scaling form. By enforcing consistency between the distribution’s zeroth moment derived from both the Smoluchowski equation and the scaling distribution ansatz, we find values for the scaling exponents w and z in terms of the scaling exponent τ and the kernel homogeneity λ which are not equivalent to their asymptotic, scaling forms. The predicted values do agree well, however, with intermediate time values found in simulations by Kang, Redner, Meakin, and Leyvraz [Phys Rev. A 33, 1171 (1986)]. By enforcing consistency between all moment orders, the asymptotic …

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