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  • Blackwell Publishing Ltd  (5)
  • International Union of Crystallography (IUCr)  (2)
  • American Association for the Advancement of Science (AAAS)  (1)
  • American Association of Petroleum Geologists (AAPG)
  • American Meteorological Society
  • Copernicus
  • 2000-2004
  • 1990-1994  (4)
  • 1975-1979  (4)
  • 1994  (4)
  • 1977  (4)
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  • 2000-2004
  • 1990-1994  (4)
  • 1975-1979  (4)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical prospecting 25 (1977), S. 0 
    ISSN: 1365-2478
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Physics
    Notes: Seismic reflection methods are being developed at the University of Manitoba to aid in determining fine crustal structure in the Precambrian of Manitoba and northwestern Ontario. Present-day environmental concern as well as mineshaft conditions necessitate the detonation of several smaller charges repeated, say, I times and followed by ‘vertical’ stacking. To obtain the familiar √I improvement in signal-to-noise (S:N) amplitude ratio applying the straight-sum (SS) method, one assumes, among other things, that both S:N ratio and signal variance are the same on all traces. Dropping these assumptions, as we must for our data, it becomes necessary to apply weighting coefficients to optimize the S:N ratio of the stacked trace. We still assume the signal shapes to be the same for repeated shots, so for the jth trace on the record of the ith shot we model the time series as: tij=ai (sj+nij); where ai is a scaling factor. The proper weights wi are then shown to be proportional to σsi/σ2ni where σ2 is variance, or to γi/ai where γi is S:N power ratio.Applying the weighted-stack (WS) method gives S:N amplitude ratios which are, on average, 55% of the optimal ratios expected from WS theory compared with only 24% for the SS method. The 45% shortfall in WS performance is ascribed mainly to trace-alignment (or time-delay) errors. Varying noise levels on individual traces, slight dissimilarity of signal shape, and correlated noise may also contribute to a lesser extent (in decreasing order of significance). This WS method appears to strike a good practical balance between S:N improvement and processing efficiency.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 17 (1977), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: A semi-open circuit system for measuring changes in net CO2 exchange (NCE) in single leaves of intact grasses following herbicide treatment is described and evaluated. There were significant differences in levels of inhibition and subsequent recovery of NCE in maize and eight weedy panicoid grasses following limited root uptake of atrazine (2-chloro-4-ethyl-amino-6-isopropylamino-1,3,5-triazine). cyanazine [2-chloro-4-(1-cyano-1-methylethylamino)-6-ethylamino-1,3,5-triazine] and cyprazine (2-chloro-4-cyclopropylamino-6-isopropyl-amino-1,3.5-triazine). Rate of NCE recovery was positively correlated (P = 0.05) with growth of seedlings in nutrient solution containing the herbicides. Rates of NCE recovery 〉0.9 mg CO2 per dm2 per h/h reflected rapid rates of herbicide detoxification in the leaves and a significant tolerance to preplant incorporated and postemergence applications of atra-zine, cyanazine and cyprazine. In contrast, some species, e.g. large crabgrass [Digitaria sanguinalis (L.) Scop.] and proso millet (Panicum miliaceum L.) treated with cyanazine demonstrated considerable tolerance to these treatments in spite of low NCE recovery rates indicating that factors other than foliar detoxification may play an important role in the tolerance of some grasses to 2-chloro- 1,3,5-triazine herbicides.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Atrazine [2-chloro-4-(ethylaminol-6-(isopropyl-amino)-s-triazine] resistant biotypes of lamb's quarters (Chenopodium athum L) were reported in the maize growing areas of Ontario, where the herbicide had been used fur a number of years. Field samples from four locations proved tolerant to higber than recommended rates of atrazine in controlled environment screening trials. A resistant biotype was not killed with up to 40 kg/ha atrazine. Diuron at 5 x10-5 M inhibited the Hill reaction with isolated chloroplasts of resisiant and susceptible biotypes of lamb's-quarters. However, with 10-4 M atrazine, the photochemical activity was inhibited in chloroplasts isolated from the susceptible biotype but not in chloroplasts from the resisiant biotype. With maize chloroplasts, inhibition with 10-4 M atrazine was the same as with the susceptible biotype of lamb's-quarters. These studies suggested that a new mechanism of intraspecific resistance in lamb's quarters to atrazine was involved, other than differences in uptake, translocation and metabolism reported with interspecific comparisons involving the s-triazines and other herbicides, It was also concluded that atrazine and diuron did not have precisely the same mechanism of action as photosynthetic inhibitors with lamb's-quarters, and that external and or internal structure or function of chloroplasts in relation to atrazine inhibition can vary significantly even in biotypes of the same species.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Water and environment journal 8 (1994), S. 0 
    ISSN: 1747-6593
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Increasing restrictions on sewage sludge disposal routes and the tightening of treatment requirements have led to an escalation of sludge-disposal costs which are out of proportion to other sewage-treatment costs: consequently reducing sludge volume is becoming increasingly cost-effective. Consolidation of anaerobically digested sludge has traditionally been difficult and takes many weeks in secondary digesters or deep storage tanks. Pre-aeration of the sludge using the Aercon process can enable consolidation to take place in days instead of weeks.This paper reports the results of a pilot-scale plant designed to investigate further the mechanism by which aeration speeds up consolidation. It was concluded that the rate of consolidation depended on aeration intensity and cooling of the sludge. Inhibition of anaerobiosis was more important than gas stripping in enhancing consolidation.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 118 (1994), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The angular variation of the median destructive field (MDF) of magnetite particles has been determined by subjecting anisotropic samples carrying an isothermal remanent magnetization (IRM) to static AF demagnetization, with the AF at an angle to the IRM. The alignment was produced by dispersing the magnetite particles in resin in the presence of a magnetic field thus making the sample anisotropic. After tumble demagnetization, an IRM in 80 mT was given to each sample along the alignment axis. 11 different particle sizes were used covering the range 0.7–82 μm. The results for all the samples are remarkably similar in that the MDF is smallest when the AF is applied parallel to the alignment axis and greatest when the AF is perpendicular to the axis. The results are also very similar to those found experimentally for single-domain ‘tape’ particles and indicate that the reversal mechanism even in the smallest particles is not by coherent reversal as in the Stoner-Wohlfarth model. The angular variation of the MDF for all the particle sizes is described quite well by a function derived by Aharoni for single-domain particles. The MDF at θ= 0 is found to be inversely proportional to the square root of the particle size.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: Computing provision is of major concern to synchrotron radiation researchers. An overview is presented of the computing facilities for synchrotron radiation work at the Synchrotron Radiation Source, Daresbury Laboratory. Data acquisition, reduction and analysis are seen as an integrated activity essential for full utilization of beam time. We discuss the evolution of data-acquisition systems from stand-alone systems of limited computing power, to a unified project computing village using state-of-the-art equipment for combined-technique, high-data-rate experiments. A brief account of software packages for data reduction and analysis is also given.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 33 (1977), S. 2117-2120 
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 8
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-02-18
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Lamb, G D -- Fryer, M W -- Stephenson, D G -- New York, N.Y. -- Science. 1994 Feb 18;263(5149):986-8.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8310298" target="_blank"〉PubMed〈/a〉
    Keywords: Acetates/chemistry/metabolism ; Adaptation, Physiological ; Animals ; Calcium/*metabolism ; Calcium Channels/*metabolism ; Dogs ; Electrodes ; Ethylenediamines/chemistry/metabolism ; Myocardium/*metabolism ; Photolysis
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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