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  • Blackwell Publishing Ltd  (65)
  • 2000-2004  (22)
  • 1985-1989  (43)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Bulletin of economic research 39 (1987), S. 0 
    ISSN: 1467-8586
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: Several techniques for solving dynamic rational expectations models have been proposed. This paper puts forward an alternative method for discrete time models, which is significantly simpler to use in practice. That solution is used to derive and compute optimal policy selections (incorporating ‘noncausal’ effects) which, by exploiting the discrete time framework, are also time consistent when sequentially reoptimized. Those decisions are shown to contain an optimal open loop component plus an innovations dependent correction mechanism. A numerical example is used to verify these properties, and to demonstrate the superiority of this policy selection technique over recursive methods (e.g. dynamic programming).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    R & D management 15 (1985), S. 0 
    ISSN: 1467-9310
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: ‘Expert Systems’ or intelligent knowledge-based computer systems can be expected to have a considerable impact in the near future on the dissemination and use of technical expertise in practical situations. The potential benefits of such an approach to decision-making in applied science domains, for example, in anti-corrosive coating selection, are considerable. This paper argues, therefore, that a premium must be placed on such a system's performance as a communicator.The structure and behaviour of a classical ‘production system’ are briefly described, and the communicative ability of such a system is analysed. This critical examination of a production system's question-answering capabilities highlights the inherent restrictions which the structure of this kind of system places on its explanatory and justificatory powers. An outline design for a less inhibitive structure is presented.It is argued that the form in which the system provides ‘answers’ after the completion of a problem-solving session, may not yield sufficient appropriate information to the user, and a possible alternative view of a ‘solution schema’ is proposed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Industrial relations journal 19 (1988), S. 0 
    ISSN: 1468-2338
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Notes: This article seeks to clarify the meaning of ‘Japanisation’ in the British economic context, and distinguishes at least three variants: direct, mediated and permeated or full. It is argued that a more satisfactory analysis needs to take account of the interrelationships between economic structures, economic systems, organisational units and employment practices.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    International journal of consumer studies 28 (2004), S. 0 
    ISSN: 1470-6431
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 16 (2000), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. There is increasing evidence that phosphorus has been accumulating in the surface horizons of agricultural soils to the extent that some soils represent a potential diffuse source of pollution to surface waters. The relationships between equilibrium phosphorus concentration at zero sorption (EPC 0) of soil and a number of soil physicochemical variables were investigated in the surface layers of arable and grassland agricultural soils sampled from the Thame catchment, England. Soil EPC0 could be predicted from an equation including soil test (Olsen) P, soil phosphate sorption index (PSI) and organic matter content (OM) (R2=0.88; P〈0.001) across a range of soil types and land use. The simple index Olsen P/PSI was found to be a good predictor of EPC0 (R2=0.77; P〈0.001) and readily desorbable (0.02 m KCl extractable) P (R2=0.73; P〈0.001) across a range of soil types under arable having soil organic matter contents of 〈10%.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 17 (2001), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Demand for water from catchments dominated by upland peat as a source of drinking water supplies in the UK is likely to increase in the future as demand per capita continues to rise (Thomsen 1990) and/or summer droughts increase in frequency (Arnell 1992). Concern has been expressed in recent years over rising colour levels (related to dissolved organic carbon (DOC) and iron (Fe)) from such catchments (e.g. Kay et al. 1989) causing reduced drinking water quality. One of the major causes of increased DOC concentrations is rewetting following periods of relative drought (Mitchell & McDonald 1992). Experimental rewetting of a naturally drained wetland in Mid-Wales over four years was found to substantially increase the concentrations of DOC, and Fe in the pore-water, with peak values of 〉60 mg dm–3 (Fe) and 〉300 mg dm–3 (DOC) after rewetting, compared with typical values of 〈1 mgdm–3 (Fe) and 〈15 mg dm–3 (DOC) under the drained conditions. Seasonal peak concentrations of Fe and DOC have since remained at these higher levels. Rewetting produced a selective enrichment of the 〉5000 to 〈90 000 apparent molecular weight (AMW) material and this fraction was found to yield peak Fe concentrations. Two additional peaks of DOC were also found in the experimental wetland (not present in the control wetland), of 〉90 000 to 〈200 000 AMW and 〉200 000 AMW material. The AMW spectrum of DOC in the experimental wetland changed with season, and the 〉90 000 to 〈200 000 AMW fraction could only be seen in spring, representing a transient pool of carbon that is rapidly transformed in or transported from the wetland. These findings suggest that rewetting of peatland following drought (e.g. due to climate change) has the potential to reduce water quality. Moreover, recent interest in restoration (rewetting) of drained peatlands (Wheeler & Shaw 1995) could create an additional source of DOC rich water.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 20 (2004), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Results from recent studies of peatland biogeochemistry suggest that appropriate soil water sampling techniques are required in order to advance our understanding of peatland soil systems. In a comparative field experiment, concentrations of inorganic solutes and dissolved organic carbon (DOC) were measured in soil water extracted at a depth of 10 cm beneath the surface of deep peat by three techniques: zero-tension (z-t) lysimeters, PTFE suction samplers, and polysulfone suction samplers. The majority of solute concentrations were broadly similar, but mean concentrations of silicon, DOC, iron and aluminium in water extracted by z-t lysimeters and PTFE samplers were in ratios of 1:5; 1:2; 1:5 and 1:3 respectively. Mean conductivity and concentrations of chloride and hydrogen ion were significantly larger in the z-t lysimeter samples, which had sodium, potassium and magnesium to chloride ratios that were very similar to local rainfall. The z-t lysimeters appeared to sample macropores preferentially, while the suction samplers collected micropore water.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Soil use and management 4 (1988), S. 0 
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. People in rural areas have disposed of their wastes on land for centuries, relying on the soil's ability to degrade and render harmless any toxic elements the wastes may contain. Leather tanneries produce a large amount of sludge and liquid wastes. The liquids contain much sodium and in most circumstances adversely affect both the soil and groundwater. However, in some countries they are used for irrigation. The sludges contain nitrogen, calcium, magnesium, phosphorus, trivalent chromium and some sodium. Given careful management these sludges can be used as soil amendments, either directly or after composting. Application rates of about 200 tonnes ha−1 have proved toxic to crops in pot trials, though larger applications than this have not adversely affected crops in the field. Much smaller rates, of less than 20 tonnes ha−1, have been used in the field to minimize nitrate contamination of groundwater. The effects of CrIII depend on complex interactions between the sludge, the soil to which it is added and the plant species grown. Safe limits for the disposal of the sludges and their long term effects are not known.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Fiscal studies 10 (1989), S. 0 
    ISSN: 1475-5890
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Economics
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. Boreholes have been constructed at eight sites on the Permo-Triassic Sandstone and Chalk aquifers to assess the extent of chemical and microbiological contamination emanating from unlined farm manure stores. Slurry along fracture faces in the Chalk was found on cores taken from beneath two stores. Porewaters from the Chalk sites and one of the Sandstone sites were discoloured and showed high concentrations of nitrate, ammonium and organic carbon to depths in excess of 10 m. Although Cryptosporidia and Escherichia coli O157 were found in many of the cattle slurry lagoons, neither were found in the aquifer material beneath. The self-sealing of unlined slurry stores is seen as a crucial step in minimizing leakage. A simple mass balance shows farm boreholes near to contaminant sources are at greater risk than public supply wells. Contaminant modelling shows discontinuing use of an unlined farm manure store will lead to little difference in solute concentrations over the short to medium term. Groundwater is most at risk where the water table is shallow since direct hydraulic connection between the lagoon base and the water table considerably increases the rate of vertical migration. This is of greatest significance for pathogens that are thought to be relatively short lived in the subsurface. Under the majority of situations minimal threat is posed to potable groundwater drinking supplies.
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