International perspectives on part-time farming: A review     

Ada Cavazzani  Anthony M. Fuller 《GeoJournal》1982,6(4):383-389

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The coronal disturbance of 1972, August 12     

Riddle  Anthony C.  Hansen  Richard T.  Tandberg-Hanssen  Einar 《Solar physics》1974,36(1):171-178

Using the observed data for metric and hectometric type III radio bursts, the dependence of burst characteristics on the solar longitude has been examined over a wide frequency range. It is found that there exists an east-west asymmetry for the extension of metric type III bursts into hectometric wavelength range. In particular, hectometric bursts are rarely observed for solar flares associated with metric bursts eastward solar longitude 60°E. Furthermore, for eastern longitudes, the low frequency radio observations show a large dispersion in drift time interval.  相似文献   

Super-speed centrifugation at sea using a gimballed platform     

Anthony W. Young  Joel D. Cline 《Estuarine, Coastal and Shelf Science》1983,16(2):145-150

The use of a super-speed centrifuge at sea for the recovery of suspended solids or interstitial pore fluids requires a stabilizing platform. In this report, we describe a simple platform gimball and magnetic rotor stabilizer that have been fitted to a Sorvall model SS_?3 super-speed centrifuge. In principle, any centrifuge of comparable weight (86 kg) could be easily adapted for use at sea with gimbals of similar design.The magnetic rotor coupler is designed to eliminate rotor precession when the centrifuge is operated at sea. This attachment is particularly useful when the Sorvall SS_?3 (equipped with a conventional rotor) is used to recover interstitial pore fluids.  相似文献   

On the evolution of interacting,magnetized, galactic plasmas     

Anthony L. Peratt  James C. Green 《Astrophysics and Space Science》1983,91(1):19-33

The advent of three-dimensional, electromagnetic, and fully relativistic particle simulations allows a detailed study of a magnetized, rotating plasma, galaxy model. When two such models are simulated, an interaction yielding results resembling observational data from double radio sources, including the emission of synchrotron radiation, are obtained. Simulation derived morphologies, radiation intensities, frequency spectra, and isophote patterns are directly compared to observations. The constituent plasma parameters associated with the source Cygnus A are found to ben _e =1.8×10^?3 cm^?3,T=2.8 keV,B=20–30 gamma, with a small population of electrons accelerated to GeV energies by a rotation induced electric field. The results of these simulations, involving a computational resource of five CDC 7600 and five Cray-1 computers, strongly supports an inhomogeneous version of the Klein world model.  相似文献   

Environment aspects of manganese nodule mining     

Anthony F. Amos  Oswald A. Roels 《Marine Policy》1977,1(2):156-163

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Geochemical stability of fine-grained silicic Holocene tephra in Iceland and Scotland     

Andrew J. Dugmore  Anthony J. Newton  David E. Sugden  Gudrun Larsen 《第四纪科学杂志》1992,7(2):173-183

This paper tests two assumptions fundamental to the use of fine-grained silicic tephras from Iceland for creating chronological frameworks in northwest Europe. It is shown firstly, that glass shards can retain their overall chemical integrity on at least a four millennial time-scale in contrasting depositional environments in Iceland and Scotland, and secondly, that an acid digestion process, the most practical method for extracting tephra from peat, does not significantly bias the results of major element analysis by electron microprobe. The implication is that there is great potential and an appropriate method for developing both the resolution and the spatial coverage of chronologies based on silicic Icelandic tephras in northwest Europe.  相似文献   

Blowing in the wind. II. Creation and redistribution of refractory inclusions in a turbulent protoplanetary nebula     

Jeffrey N. Cuzzi  Sanford S. Davis  Anthony R. Dobrovolskis 《Icarus》2003,166(2):385-402

Ca-Al rich refractory mineral inclusions (CAIs) found at 1-6% mass fraction in primitive chondrites appear to be 1-3 million years older than the dominant (chondrule) components which were accreted into the same parent bodies. A prevalent concern is that it is difficult to retain CAIs for this long against gas-drag-induced radial drift into the Sun. We reassess the situation in terms of a hot inner (turbulent) nebula context for CAI formation, using analytical models of nebula evolution and particle diffusion. We show that outward radial diffusion in a weakly turbulent nebula can overcome inward drift, and prevent significant numbers of CAI-size particles from being lost into the Sun for times on the order of 10⁶ years. CAIs can form early, when the inner nebula was hot, and persist in sufficient abundance to be incorporated into primitive planetesimals at a much later time. Small (?0.1 mm diameter) CAIs persist for longer times than large (?5 mm diameter) ones. To obtain a quantitative match to the observed volume fractions of CAIs in chondrites, another process must be allowed for: a substantial enhancement of the inner hot nebula in silicate-forming material, which we suggest was caused by rapid inward drift of meter-sized objects. This early in nebula history, the drifting rubble would have a carbon content probably an order of magnitude larger than even the most primitive (CI) carbonaceous chondrites. Abundant carbon in the evaporating material would help keep the nebula oxygen fugacity low, plausibly solar, as inferred for the formation environment of CAIs. The associated production of a larger than canonical amount of CO₂ might also play a role in mass-independent fractionation of oxygen isotopes, leaving the gas rich in ¹⁶O as inferred from CAIs and other high temperature condensates.  相似文献   

First results from the Very Small Array – I. Observational methods     

Robert A. Watson  Pedro Carreira  Kieran Cleary  Rod D. Davies  Richard J. Davis  Clive Dickinson  Keith Grainge †  Carlos M. Gutiérrez  Michael P. Hobson  Michael E. Jones  Rüdiger Kneissl  Anthony Lasenby  Klaus Maisinger  Guy G. Pooley  Rafael Rebolo  José Alberto Rubiño-Martin ‡  Ben Rusholme §  Richard D. E. Saunders  Richard Savage  Paul F. Scott  An&#;e Slosar  Pedro J. Sosa Molina  Angela C. Taylor  David Titterington  Elizabeth Waldram  Althea Wilkinson 《Monthly notices of the Royal Astronomical Society》2003,341(4):1057-1065

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Towards a theory for type III solar radio bursts     

Dean F. Smith  Anthony C. Riddle 《Solar physics》1975,44(2):471-483

The procedure developed in Smith (1974) to model the radiation source for type III bursts is modified to include scattering of radiation in the source itself. Since the inhomogeneities in the source must have the same statistical properties as the inhomogeneities used in tracing radiation from the source to the observer, these two parts of the type III problem are no longer uncoupled. Thus we use inhomogeneities consistent with the scattering inhomogeneities of Steinberg et al. (1971) and Riddle (1974) and apply the procedure to an archetype ‘fundamental-harmonic’ pair observed at Culgoora on 28 September, 1973 at 0319 UT. We find that it is impossible to model this burst with a source which is homogeneous in the sense that every part of the source has the same energy density in plasma waves. The density inhomogeneities in the source severely hamper amplification of the supposed fundamental. Possible ways out of this dilemma are discussed, including second harmonic pairs and a source with an inhomogeneous distribution of plasma waves. It is concluded that none of the possibilities are completely satisfactory to explain present observations and suggested that critical observations are missing.  相似文献   

The Distribution and Significance of Evaporitic Weathering Products on Antarctic Meteorites     

Michael Anthony Velbel 《Meteoritics & planetary science》1988,23(2):151-159

Abstract— The distribution of white evaporitic deposits differs among different meteorite compositional groups and weathering categories of Antarctic meteorites. Evaporites occur with unusual frequency on carbonaceous chondrites, and are especially common in carbonaceous chondrites of weathering categories A and B. Among achondrites, weathering categories A and A/B show the most examples of evaporite weathering. Unlike carbonaceous chondrites and achondrites, most evaporite-bearing ordinary (H and L) chondrites are from rustier meteorites of weathering categories B and, to a lesser degree, B/C and C. LL chondrites are conspicuous by their complete lack of any evaporitic weathering product. Almost two-thirds of all evaporite-bearing meteorites belong to weathering categories A, A/B, and B. Where chemical data are available, surficial evaporite deposits are associated with elemental anomalies in meteorite interiors. Meteorites of weathering classes B, A/B, and even A may have experienced significant element redistribution and/or contamination as a result of terrestrial exposure. Evaporite formation during terrestrial weathering cannot be neglected in geochemical, cosmochemical, and mineralogical studies of Antarctic meteorites. A lower-case “e” should be added to the weathering classification of evaporite-bearing Antarctic meteorites, to inform meteorite scientists of the presence of evaporite deposits and their associated compositional effects.  相似文献