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  • 1
    Electronic Resource
    Electronic Resource
    A preliminary classification of running-water sites in Great Britain based on macro-invertebrate species and the prediction of community type using environmental data (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 14 (1984), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. Macro-invertebrate species lists were obtained for 268 sites on forty-one river systems throughout Great Britain by qualitative sampling in spring, summer and autumn. Information on twenty-eight environmental variables was also collated for each site. The sites were ordinated on the basis of their species content using detrended correspondence analysis (DCA) and classified by two-way indicator species analysis (TWINSPAN). Correlation coefficients between ordination scores and single environmental variables indicated that Axis 1 distinguished between types of rivers and Axis 2 reflected variation along the length of rivers. A preliminary classification of sites into sixteen groups has been proposed, together with a key which allows new sites to be classified. Information on the species and environmental features which characterize each group is also presented.2. Multiple discriminant analysis (MDA) was employed to predict the group membership of the 268 sites using the twenty-eight environmental variables. 76.1% of sites were classified correctly. An independent assessment of predictive ability using forty test sites yielded a 50% success rate. Predictive ability was higher for the classification presented in this paper than in fifteen additional classifications produced using data from single seasons and/or different taxonomic treatments.3. TWINSPAN and MDA were found to be useful approaches to the classification of running-water sites by their macro-invertebrate fauna and the prediction of community type (as indicated by the occurrence of species in the sites comprising the group) using environmental variables. Extension of the scope of the classification, coupled with the use of additional environmental variables to increase predictive ability, is now in progress.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1984.tb00039.x
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  • 2
    Electronic Resource
    Electronic Resource
    The influence of seasonal and taxonomic factors on the ordination and classification of running-water sites in Great Britain and on the prediction of their macro-invertebrate communities (1984)
    Oxford, UK : Blackwell Publishing Ltd
    Freshwater biology 14 (1984), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: SUMMARY. 1. Macro-invertebrate samples were collected from 268 running-water sites in Great Britain in each of three seasons (spring, summer and autumn). A combined seasons’treatment was generated by amalgamating the individual seasons’data. These four seasonal options were each subjected to four distinct taxonomic analyses differing in level of identification and whether the data were quantitative or qualitative. Thus sixteen data-sets were available for analysis. Environmental data on physical and chemical variables, macrophyte cover and date of sampling were also recorded for each site.2. All sixteen data-sets were ordinated by detrended correspondence analysis and classified by two-way indicator species analysis. There were strong correlations between the sixteen ordinations and significant concordance between classifications.3. The relationships between ordination scores and single environmental variables were investigated. Muhiple discriminant analysis was used to fit environmental data to eight selected classifications covering the full range of seasonal and taxonomic treatments. The environmental variables most useful in distinguishing between rivers were substratum characteristics, alkalinity and total oxidized nitrogen. Within-river differences were often highly correlated with discharge, distance from source, width and depth. Slope and altitude contributed strongly to both between-river and within-river distinctions.4. Between-site variation (beta diversity), eigenvalues of ordination, the reliability of classifications, the proportion of sites correctly assigned to their biological group using environmental data and the standardized similarity between observed and predicted fauna were all higher when identifications were taken to species level, rather than one of three family treatments. Qualitative data on a reduced list of families gave comparable or better results than more detailed family treatments.5. Combined seasons’data enabled better categorization and prediction than single season's.6. The values of the Czekanowski Index of Similarity between the observed and predicted fauna of test sites were close to realistic maximum values.7. Recommendations are made concerning potential usages of the various classifications. The species level classification has uses in the field of conservation and in the prediction of biological response to environmental change. The family level classifications have value in developing local site inventories and in the interpretation of pollution surveillance programmes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2427.1984.tb00040.x
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  • 3
    Electronic Resource
    Electronic Resource
    Α comparison of alternative techniques for prediction of the fauna of running-water sites in Great Britain (1999)
    Oxford, UK : Blackwell Science, Ltd
    Freshwater biology 41 (1999), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 1. Early versions of the river invertebrate prediction and classification system (RIVPACS) used TWINSPAN to classify reference sites based on the macro-invertebrate fauna, followed by multiple discriminant analysis (MDA) for prediction of the fauna to be expected at new sites from environmental variables. This paper examines some alternative methods for the initial site classification and a different technique for prediction.2. A data set of 410 sites from RIVPACS II was used for initial screening of seventeen alternative methods of site classification. Multiple discriminant analysis was used to predict classification group from environmental variables.3. Five of the classification–prediction systems which showed promise were developed further to facilitate prediction of taxa at species and at Biological Monitoring Working Party (BMWP) family level.4. The predictive capability of these new systems, plus RIVPACS II, was tested on an independent data set of 101 sites from locations throughout Great Britain.5. Differences between the methods were often marginal but two gave the most consistently reliable outputs: the original TWINSPAN method, and the ordination method semi-strong hybrid multidimensional scaling (SSH) followed by K-means clustering.6. Logistic regression, an alternative approach to prediction which does not require the prior development of a classification system, was also examined. Although its performance fell within the range offered by the other five systems tested, it conveyed no advantages over them.7. This study demonstrated that several different multivariate methods were suitable for developing a reliable system for predicting expected probability of occurrence of taxa. This is because the prediction system involves a weighted average smoothing across site groupings.8. Hence, the two most promising procedures for site classification, coupled to MDA, were both used in the exploratory analyses for RIVPACS III development, which utilized over 600 reference sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.1999.00376.x
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  • 4
    Electronic Resource
    Electronic Resource
    Historical records of the occurrence of butterflies in Britain: examples showing associations between annual number of records and weather (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Global change biology 1 (1995), S. 0 
    Details
    ISSN: 1365-2486
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Notes: Historical records (1900–66) from the Lepidoptera Recording Scheme were used to examine associations with weather for three butterfly species Ladoga Camilla, Celastrina argiolus and Nymphalis polychloros. For each species, a series of equations was examined in which the number of records per year was considered to be a function of (1) the number of records in the previous year and (2) temperature or rainfall in the months leading up to the current flight-period. Significant associations with weather were found for all species. Further multiple regression equations were obtained, using a stepwise procedure to select weather variables contributing separately to annual variation in the number of records. For L. Camilla and C. argiolus, predictions from these equations were significantly correlated with data on changes in abundance for the later period 1976–91. No recent data exist for JV. polychloros, which is now very rare, or possibly extinct, in Britain. Similar historic data are available for other butterfly species and for other taxa. It is suggested that these types of data have potential for the study, and perhaps prediction, of some effects of climate change.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2486.1995.tb00010.x
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  • 5
    Electronic Resource
    Electronic Resource
    Sequential appearance of Epstein–Barr virus nuclear and lymphocyte-detected membrane antigens in B cell transformation (1981)
    [s.l.] : Nature Publishing Group
    Nature 291 (1981), S. 664-666 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] EB virus-specific memory T cells are present exclusively in seropositive individuals and can be reactivated in vitro by co-cultivation either with freshly-infected autologous B cells6 or with low numbers of cells from the autologous EB virus-transformed B cell line11. Such reactivated T-cell ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/291664a0
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  • 6
    Electronic Resource
    Electronic Resource
    Computing in crystallography edited by R. Diamond, S. Ramaseshan and K. Venkatesan (1981)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 37 (1981), S. 446-446 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567739481001022
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  • 7
    Electronic Resource
    Electronic Resource
    A strategy for combining restrained least squares with computer graphics in the refinement of protein structures (1983)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 39 (1983), S. 196-199 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A method of combining interactive molecular graphics with restrained least-squares refinement is described. This enables a researcher using the interactive computer graphics terminal to weight the shifts applied to the individual atoms in following cycles of refinement according to the confidence in their positions. The weights are incorporated into the least-squares procedure using the Marquardt factor which was originally introduced to handle the ill-conditioned case [Moss & Morffew (1982). Comput. Chem. 6, 1-3; Marquardt (1963). SIAM J. Appl. Math. 11, 431-441]. The described refinement strategy has been implemented at Birkbeck College, London, and, using avian pancreatic polypeptide (APP) as test data, some refinements have been carried out. In order to compare the results of these refinements, histograms have been drawn that show the distribution of distances between the corresponding atoms in the different models. These histograms show that the model is improved by including the 'confidence' weighting. An improvement of 7.5% was achieved in the mean distance between the corresponding atoms in the fully refined model and a model resulting from four cycles of restrained least squares. When the 'confidence' weighting was included this improvement rose to 14-0%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767383000446
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  • 8
    Electronic Resource
    Electronic Resource
    Crystallization and preliminary X-ray diffraction studies of α-toxin from two different strains (NCTC8237 and CER89L43) of Clostridium perfringens (1998)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 54 (1998), S. 1425-1428 
    Details
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The α-toxin of Clostridium perfringens is the major virulence determinant for gas gangrene in man. The gene encoding the α-toxin has been cloned into E. coli from two strains of the bacterium (NCTC8237 and CER89L43) and subsequently purified to homogeneity. The two strains of α-toxin differ by five amino acids, resulting in the toxin from NCTC8237 being sensitive to chymotrypsin digestion while that from CER89L43 is resistant. The α-toxin from each of these strains has been crystallized in two different forms by the hanging-drop vapour-diffusion method at 293 K. CER89L43 form I crystals belong to space group R32 and have two molecules in the crystallographic asymmetric unit and a unit cell with a = b = 151.4, c = 195.5 Å, α = β = 90, γ = 120°. The crystals diffracted to dmin = 1.90 Å. The characteristics of the NCTC8237 form I crystals have already been reported. The form II crystals from both strains belong to space group C2221 with one molecule in the crystallographic asymmetric unit and, for strain CER89L43, have cell dimensions a = 61.05, b = 177.50, c = 79.05 Å, α = β = γ = 90°, while for strain NCTC8237 the cell dimensions are a = 60.50, b = 175.70, c = 80.20 Å, α = β = γ = 90°. The crystals diffracted to maximum resolutions of 1.85 and 2.1 Å for the CER89L43 and the NCTC8237 strains, respectively.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0907444998005186
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  • 9
    Electronic Resource
    Electronic Resource
    Ribonuclease-A: least-squares refinement of the structure at 1.45 Å resolution (1982)
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 38 (1982), S. 2210-2217 
    Details
    ISSN: 1600-5740
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0567740882008346
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  • 10
    Electronic Resource
    Electronic Resource
    6,7-Dimethoxy-3-(5,6,7,8-tetrahydro-4-methoxy-6-methyl-1,3-dioxolo[4,5-g]isoquinolin-5-yl)-1(3H)-isobenzofuranone [(−)-α-narcotine], C22H23NO7, a structural analogue of GABA (1984)
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 40 (1984), S. 1960-1963 
    Details
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108270184010222
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