Interchange of Data between Geographic Information Systems     

RICHARD PASCOE  JOHN PENNY 《New Zealand geographer》1990,46(1):26-28

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Views on the late Geological Museum     

NORMAN E. BUTCHER  RICHARD WILDING  DEREK GREEN  DAVID A. ROTHERY  MICHAEL BAMLETT 《Geology Today》1992,8(2):56-57

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The application of Kalman smoother theory to the estimation of 4DVAR error statistics     

RICHARD MÉNARD  ROGER DALEY 《地球，A辑:动力气象学与海洋学》1996,48(2):221-237

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Global geographies of innovation diffusion: the case of the Australian cattle industry     

MATTHEW TONTS  RICHARD YARWOOD†  ROY JONES‡ 《The Geographical journal》2010,176(1):90-104

The geographies and histories of the introduction of cattle breeds to Australia in the period since white settlement are documented as an example of the diffusion of agricultural innovations. Three phases of development are identified: a colonial expansion phase from the late eighteenth to the early twentieth century during which a number of primarily British cattle breeds were imported by the colonial settlers; an innovative phase in the mid twentieth century when both governments and private interests sought to produce or import new breeds deemed to be better adapted to Australian environments; and a multifunctional phase in recent decades. In this final phase, government deregulation and new technologies, such as the long distance transport of genetic packages, have facilitated the importation and development of many new cattle breeds in Australia. While this has produced a significant rise in the total number of breeds represented nationally, many recent and historic breeds currently exhibit extremely small numbers and a few generally well-established breeds such as Holstein, Hereford and Angus still dominate the national herd. This study of changing breed types and introductions provides some evidence of post-productivism and of a multifunctional transition in that several cattle breeds favoured by hobby farmers and boutique breeders are now represented, but the aggregate numbers for these breeds remain small and the numbers for several of the traditional (or colonial) breeds are currently in decline. Overall, it is apparent that Australia's cattle industry retains a strongly productivist ethos and that, particularly given the country's very great environmental variation, its levels of breed diversity remain low.  相似文献   

Freshwater calcite precipitates from in vitro mesocosm flume experiments: a case for biomediation of tufas   总被引：2，自引：0，他引：2  

MARTYN PEDLEY  MIKE ROGERSON  RICHARD MIDDLETON 《Sedimentology》2009,56(2):511-527

Freshwater carbonates (tufas) develop today from the Arctic to the tropics, many being localized about springs and upper water courses. Some Quaternary tufas, especially in the Mediterranean region, extend over tens of square kilometres and exceed 30 m in thickness. Radiometric dating of Holocene deposits shows that many have accumulated at an average rate of 1 mm year^?1. However, local precipitation may be much faster and some Holocene deposits may even have outpaced their tropical marine carbonate counterparts. Recently, the study of active sites has attempted to quantify the precipitation mechanisms which lead to tufa deposition. However, field observation and sampling procedures suffer from the inherent disadvantages of uncontrolled fluctuations in environmental conditions during the study programme. These disadvantages compromise any interpretations, particularly where controls on spar versus micrite precipitation are concerned. Many of these problems have been overcome in the current study by the construction and operation of laboratory mesocosm flumes which simulate the natural conditions (e.g. pH, flow rate, ambient temperature and daylight) in which freshwater carbonate (tufa) is deposited. Three mesocosms were supplied with natural river water from tufa precipitating streams and two mesocosms were supplied with UV‐treated (sterile) river water from the same source. One of the untreated flume mesocosms was linked with a calcium reactor, which replaced calcium ions removed during the precipitation process in order to maintain tufa growth over extended experimental runs. Low‐magnesium calcite precipitates (both rhombic sparite grown from long‐crystallite dendrites and short‐crystallite dendrite triad precursors) and micrite peloids (grown from spherulitic precursors) were precipitated in intimate association with biofilm (extracellular polymeric substances) within the four mesocosms supplied with natural river water. Virtually, no tufa‐like precipitate was obtained from the flumes supplied with UV‐treated river water. A second extended run flume experiment was also carried out for comparison purposes using a calcium hydroxide solution in deionized water. Collectively, these experiments provide convincing evidence confirming that the presence of a microbial biofilm strongly influences the precipitation of carbonates in riverine freshwater settings. In particular, experimental results show that micro‐peloidal micrite and short‐crystallite calcite dendrites are only produced in the presence of microbial extracellular polymeric substances.  相似文献   

Late Middle Pleistocene glaciation in East Anglia, England   总被引：1，自引：0，他引：1  

PHILIP L. GIBBARD  ANTTI H. PASANEN  RICHARD G. WEST  JUHA PEKKA LUNKKA  STEVE BOREHAM  KIM M. COHEN  CHRISTOPHER ROLFE 《Boreas: An International Journal of Quaternary Research》2009,38(3):504-528

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IMMIGRATION POLICY AND MIGRATION TO NEW ZEALAND FROM THE SOUTH PACIFIC, 1986–87     

RICHARD BEDFORD 《New Zealand geographer》1987,43(1):36-40

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Fossils explained 2: Trilobites     

RICHARD FORTEY 《Geology Today》1985,1(3):93-94

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PARAXIAL RAY TRACING IN 3D INHOMOGENEOUS,ANISOTROPIC MEDIA1     

RICHARD L. GIBSON  ARCANGELO G. SENA  M. NAFI TOKS Z 《Geophysical Prospecting》1991,39(4):473-504

Many investigations of the propagation elastic waves within the earth require a technique for producing synthetic seismograms which is capable of modelling 3D propagation effects. Ray methods are an excellent option for these problems, because they can be made fully 3D and allow a relatively quick and flexible computation of synthetic seismograms. However, the two point problem of finding the ray which connects exactly a specific source and receiver, may still be difficult and time consuming. Therefore, application of the paraxial method, which allows extrapolation of the information on a given ray to nearby receiver locations, is very valuable. With this approach, great savings in computation time and significant simplification of computer codes are possible. We investigate the application of the paraxial ray method to two problems in which the effects of 3D seismic wave propagation are important. The first is a model of a reef structure. In this case, we consider synthetic seismograms for a VSP experimental configuration. When the SV source and well are located along the axis of the reef, only 2D propagation effects are observed. If the source-receiver plane is located to the side of the reef, however, the 3D shape of the reef causes significant amplitudes to be predicted for shear-wave arrivals on the transverse component of the synthetic seismograms. The second example is a ID, layered earth model, but it includes two layers which are azimuthally anisotropic due to the presence of aligned, vertical fractures. This anisotropy leads to 3D raypaths. Synthetic seismographs are presented for a cross-hole geometry both for an equivalent isotropic model and for the direction parallel to the fractures and at an angle of 45° to the fractures in the anisotropic case. These synthetics show that the differences between the isotropic case and the case for source and receivers aligned with the plane of the fractures are small and subtle. On the other hand, the predictions for the direction at 45° to the cracks show shear-wave splitting and significant transverse component signal. These results have important implications for both modelling and for applications such as tomography. It is clear that for some of the cases considered, a 2D algorithm will lead to errors in interpretation of data. In addition, ray-based tomographic techniques will have great difficulty in obtaining a well-defined 2D planar image when the signals are propagating in regions outside the image plane.  相似文献   

Rank exposure index on a Silurian carbonate tidal flat     

RICHARD SMOSNA  STEVEN M. WARSHAUER 《Sedimentology》1981,28(5):723-731

Adequate discrimination between ancient intertidal and supratidal limestones and dolomites is often difficult because of vagueness of terms, problems of resolution, and the fact that most ‘diagnostic’sedimentary features are not restricted to narrow environmental zones. Furthermore, the rise and fall of sea-level in restricted, epeiric seas is usually due more to storm surges than to true tides, and hence the occurrence and extent of tidal-flat inundations are quite irregular. ‘Rank exposure index’is a concept introduced (1) to quantify the relative percentage of time that sediments are subaerially exposed and (2) to produce a more refined subdivision of shoreline carbonate rocks. The scheme employed to determine this index is a combination of numerical methods: cluster analysis separates 46 Tonoloway Limestone samples (Silurian of Maryland) into groups based on 16 sedimentary, mineralogic, and organic features, and minimum spanning tree produces a connected series of the five resultant groups. These groups are then ranked in sequence from 1 (greatest subaerial exposure) to 5 (least). Rocks of rank 1 are thought to have been deposited at the highest position within the tidal zone, as on a beach ridge. Rocks of decreasing rank reflect greater frequency of flooding. Those of rank 5 represent sediments deposited closest to low-water level, as in a tidal pond. Rock type, mineralogy, fossil content, algal stromatolites, and sedimentary structures are closely related to exposure rank as interpreted for the Tonoloway carbonates. Rank exposure index, therefore, is a semi-quantitative measure to aid in the detailed reconstruction of ancient shoreline environments.  相似文献