A note on the determination of ozone concentrations from radio-meteor duration distributions.     

J. Jones  M. Simek 《Earth, Moon, and Planets》1995,68(1-3):329-338

Hajduk, et al (1992) have drawn attention to a possible source of error in our earlier analysis of visual and radar observations of shower meteors from which we calculated the ozone concentration at meteor heights. We have considered their main criticism that the features of our data which we used to calculate the ozone concentration may have been due to the constraint that our meteors had to be observed by both methods. We have shown that observations collected from radar-only systems show very similar characteristics and that these can be analysed without recourse to visual data to produce very similar results to those from our original analysis. Presented at theInternational Conference on Meteoroids 23 – 31 August 1994 in Bratislava.Submitted to Earth, Moon and Planets  相似文献   

Transmission electron microscopy of subsolidus oxidation and weathering of olivine     

Jillian F. Banfield  David R. Veblen  Blair F. Jones 《Contributions to Mineralogy and Petrology》1990,106(1):110-123

Olivine crystals in basaltic andesites which crop out in the Abert Rim, south-central Oregon have been studied by high-resolution and analytical transmission electron microscopy. The observations reveal three distinct assemblages of alteration products that seem to correspond to three episodes of olivine oxidation. The olivine crystals contain rare, dense arrays of coherently intergrown Ti-free magnetite and inclusions of a phase inferred to be amorphous silica. We interpret this first assemblage to be the product of an early subsolidus oxidation event in the lava. The second olivine alteration assemblage contains complex ordered intergrowths on (001) of forsterite-rich olivine and laihunite (distorted olivine structure with Fe³⁺ charge balanced by vacancies). Based on experimental results for laihunite synthesis (Kondoh et al. 1985), these intergrowths probably formed by olivine oxidation between 400 and 800°C. The third episode of alteration involves the destruction of olivine by low-temperature hydrothermal alteration and weathering. Elongate etch-pits and channels in the margins of fresh olivine crystals contain semi-oriented bands of smectite. Olivine weathers to smectite and hematite, and subsequently to arrays of oriented hematite crystals. The textures resemble those reported by Eggleton (1984) and Smith et al. (1987). We find no evidence for a metastable phase intermediate between olivine and smectite (M — Eggleton 1984). The presence of laihunite exerts a strong control on the geometry of olivine weathering. Single laihunite layers and laihunite-forsteritic olivine intergrowths increase the resistance of crystals to weathering. Preferential development of channels between laihunite layers occurs where growth of laihunite produced compositional variations in olivine, rather than where coherency-strain is associated with laihunite-olivine interfaces.  相似文献   

Applied statistics in atmospheric science Part A. Frequencies and curve fitting | O. Essenwanger, 1976. Elsevier,Amsterdam, 412 pp., $ 53.95.     

Richard H. Jones 《Earth》1978,14(1):75-76

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TESTING MACRO-THÜNEN MODELS BY LINEAR PROGRAMMING     

Richard C. Jones 《The Professional geographer》1976,28(4):353-361

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To the Editor, The Photogrammetric Record Remote Sensing     

A. Remote  Jones 《The Photogrammetric Record》1975,8(46):552-552

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Effects of enhanced zinc and copper in drinking water on spatial memory and fear conditioning     

L.D. Chrosniak  L.N. Smith  C.G. McDonald  B.F. Jones  J.M. Flinn 《Journal of Geochemical Exploration》2006,88(1-3):91

Ingestion of enhanced zinc can cause memory impairments and copper deficiencies. This study examined the effect of zinc supplementation, with and without copper, on two types of memory. Rats raised pre- and post-natally on 10 mg/kg ZnCO₃ or ZnSO₄ in the drinking water were tested in a fear-conditioning experiment at 11 months of age. Both zinc groups showed a maladaptive retention of fearful memories compared to controls raised on tap water. Rats raised on 10 mg/kg ZnCO₃, 10 mg/kg ZnCO₃ + 0.25 mg/kg CuCl₂, or tap water, were tested for spatial memory ability at 3 months of age. Significant improvements in performance were found in the ZnCO₃ + CuCl₂ group compared to the ZnCO₃ group, suggesting that some of the cognitive deficits associated with zinc supplementation may be remediated by addition of copper.  相似文献   

An ephemeral turbidity maximum generated by resuspension of organic-rich matter in a macrotidal estuary, S.W. Wales     

C. F. Jago  A. K. Ishak  S. E. Jones  M. R. G. Goff 《Estuaries and Coasts》2006,29(2):197-208

An ephemeral estuarine turbidity maximum (ETM) occurs at high water in the macrotidal Taf estuary (SW Wales, United Kingdom). A new mechanism of ETM formation, due to resuspension and advection of material by flood tidal currents, is observed that differs from classical mechanisms of gravitational circulation and tidal pumping. The flood tide advances across intertidal sand flats in the main body of the estuary, progressively entraining material from the rippled sands. Resuspension creates, a turbid front that has suspended sediment concentrations (SSC) of about 4,000 mg I⁻¹ by the time it reaches its landward limit which is also the landward limit of salt penetration. This turbid body constitutes the ETM. Deposition occurs at high slack water but the ETM retains SSC values up to 800 mg I⁻¹, 1–2 orders of magnitude greater than ambient SSC values in the river and estuarine waters on either side. The ETM retreats down the estuary during the ebb; some material is deposited thinly across emergent intertidal flats and some is flushed out of the estuary. A new ETM is generated by the next flood tide. Both location and SSC of the ETM scale on Q/R³ where Q is tidal range and R is river discharge. The greatest expression of the ETM occurs when a spring tide coincides with low river discharge. It does not form during high river discharge conditions and is poorly developed on neap tides. Particles in the ETM have effective densities (120–160 kg m⁻³) that are 3–4 times less than those in the main part of the estuary at high water. High chlorophyll concentrations in the ETM suggest that flocs probably originate from biological production in the estuary, including production on the intertidal sand flats.  相似文献   

New specimens of a fossil ostrich from the Miocene of Kenya   总被引：1，自引：0，他引：1  

Leona M. Leonard  Gareth J. Dyke  Cyril A. Walker 《Journal of African Earth Sciences》2006,45(4-5):391-394

Fossilised hind limb bones from the late Middle Miocene (approximately 14 million-year-old [MYA]) Fort Ternan, Kadianga West and Ngorora localities in Western Kenya indicate the presence of a new representative of the ostrich genus Struthio. These new fossils represent some of the oldest known records for Struthio yet described, slightly younger than Struthio coppensi, from the Lower Miocene of Namibia. Because the four sub-species of the modern-day ostrich (Struthio camelus camelus, Struthio camelus australis, Struthio camelus massaicus, and Struthio camelus molybdophanes) inhabit the plains of Africa, and as recently as the 1940s, a fifth sub-species was also present in the Middle East and Saudi Arabia (Struthio camelus syriacus), records of Struthio from Kenya and Namibia testify to the much wider distribution of these cursorial birds in the relatively recent past. This is further supported by the very high frequency of ostrich eggshell fragments found across Africa and Eurasia, which vastly outweighs the amount of skeletal material uncovered over the last century.  相似文献   

P. A. Siver, P. B. Hamilton, K. Stachura-Suchoples and J. P. Kociolek, Diatoms of North America The Freshwater Flora of Cape Cod, Massachusetts, USA, H. Lange-Bertalot (ed), Iconographia diatomologica annotated diatom micrographs, Vol 14     

Vivienne Jones 《Journal of Paleolimnology》2006,36(4):439-440

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Managing water resources in the British Isles in a changing environment     

Tony Jones  Geoff Petts 《Area》2006,38(1):7-8

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