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  • 1
    Electronic Resource
    Electronic Resource
    Traits of benthic macroinvertebrates in semi-natural French streams: an initial application to biomonitoring in Europe (2000)
    Oxford, UK : Blackwell Science Ltd
    Freshwater biology 43 (2000), S. 0 
    Details
    ISSN: 1365-2427
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 〈list style="custom"〉1The methods used to indicate the biological state of streams are often based on taxonomic composition, and the abundance of species or other taxa. This ‘taxonomic structure’ varies among ecoregions and cannot be applied to wider geographical areas. Therefore, we assessed the species traits of benthic macroinvertebrates from semi-natural reference sites as a potential benchmark for large-scale biomonitoring. Our purpose was to assess the stability of community structure, based on the representation of taxa and of traits, across large gradients of geology (sedimentary to granitic), altitude (65–1982 m), geographical coordinates (0° 48′ W to 7° 20′ E and 42° 52′ to 48° 44′ N), stream order (1–5) and slope (0.5–60‰).2We used invertebrate abundance data from the 62 most natural French stream sites available. These abundance data served to weight the occurrence of ‘biological’ traits, such as reproductive characteristics, mobility, resistance forms, food, feeding habits, respiration, and ‘ecological’ traits, such as preferences for temperature, trophic level, saprobity, biogeographic distribution, longitudinal zonation, substratum and current velocity.3Multivariate analyses of taxonomic composition demonstrated a clear site gradient from lowlands to uplands and from calcareous to granitic geology. In contrast, community structure based on both biological and ecological traits was stable across environmental gradients.4The frequency distribution of biological traits indicated that the stream benthos of the ‘reference sites’ had a mixture of categories which confirmed theoretical predictions for temporally stable and spatially variable habitats. A mixture of ecological trait categories also occurred at our reference sites. Thus, semi-natural benthic macroinvertebrate communities are functionally diverse. Moreover, we included an initial application of these traits to a case of slightly to moderately polluted sites to show that the impact of humans significantly changes this natural functional diversity.5Future studies should focus on the potential for various biological and ecological traits to discriminate different human impacts on the benthic macroinvertebrates of running waters, and on the integration of this functional application into a general ‘reference-condition’ approach.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2427.2000.00545.x
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  • 2
    Electronic Resource
    Electronic Resource
    L'influence du ‘décor’ et du langage dans des épreuves de type ‘logique’ portant apparemment sur l'implication (1982)
    Springer
    Educational studies in mathematics 13 (1982), S. 409-429 
    Details
    ISSN: 1573-0816
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Description / Table of Contents: Abstract In this article are presented some results of research into different aspects of behavioural response to some ‘implication’ problems. After comparing the results obtained from tests which followed the same a priori analytical logic formulae, but with different formulations, we took account of the predominant influence of these factors in the solution process, which suggested two ideas; one, that an individual at the peak of his intellectual development is capable of reasoning in certain non-mathematical contexts by following some ‘binary-logic’ formulae independent of the given problem, and two, the teaching of mathematical logic from so-called concrete examples and situations.
    Notes: Résumé La recherche dont nous donnons ici quelques résultats avait pour but l'étude de différents paramètres dans le comportement de réponse à des problèmes portant apparemment sur l'implication d'une population hétérogène quant aux niveaux scolaires. En comparant les résultats obtenus à des tests suivant a priori les mêmes schémas logiques de raisonnement mais avec des formulations et/ou des ‘décors’ différents, nous avons mis en évidence l'influence prédominante de ces facteurs dans le processus de résolution, ce qui remet en question, d'une part, l'idée qu'un individu arrivé au sommet de son développement intellectuel soit capable de raisonner, dans certains contextes non mathématiques, suivant des schémas indépendants du problème posé et assimilables à ceux de la logique binaire et, d'autre part, une pédagogie de la logique mathématique à partir d'examples et de situations dits concrets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00366620
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  • 3
    Electronic Resource
    Electronic Resource
    Copolymères du chlorure de vinylidène avec l'acrylonitrile, le chlorure de vinyle et le méthacrylate de méthyle I. Transition vitreuse (1980)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 87 (1980), S. 149-163 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Evolution of the glass transition temperature Tg of copolymers of vinylidene chloride (CVD) with acrylonitrile (AN), vinyl chloride (VC) and methyl methacrylate (MMA) versus the CVD content was studied. A Monte-Carlo model of the crystallinity of these copolymers has been developped, which allows computation of the number of comonomer defects rejected in the amorphous phase by crystallization. It was possible to explain deviations of the experimental curves from the theoretical curves (obtained from the Barton and Johnston equations) for Tg values versus the copolymer composition which take into account the sequence distribution.
    Notes: On a etudie la variation de la température de transition vitreuse TV des copolymères du chlorure de vinylidène (CVD) avec l'acrylonitrile, le chlorure de vinyle et le méthacrylate de méthyle, en fonction de la composition de ces copolymères. A l'aide d'un modèle simulant, par la méthode de Monte-Carlo, la croissance des chaînes et la cristallisation, on calcule la composition de la phase amorphe dans laquelle ont été rejetés, lors de la cristallisation, un maximum de c«défauts» comonomères. On explique ainsi, pour les copolymerès semi-cristallins riches en CVD, l'écart entre la courbe experimentale et les courbes obtenues á partir des équations de Barton et de Johnston qui tiennent compte de la microstructure linéaires.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1980.050870111
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  • 4
    Electronic Resource
    Electronic Resource
    Copolymères du Chlorure de Vinylidène avec l'Acrylonitrile et le Chlorure de Vinyle II. Étude des propriétés mécaniques en relation avec la distribution des séquencesPartie I: B. Dumont, J. Guillot, Angew. Makromol. Chem. 87 (1980) 149. (1982)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 107 (1982), S. 75-86 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Relaxations observed in random copolymers of vinylidene chloride with acrylonitrile and vinyl chloride were studied. These relaxations, which are in direct relation with the glass-transition and below glass-transition, are explained in terms of tetrads for the first ones, and of diads for relaxations in the below glass-transition range.In the region where the modulus is falling, considered as the glass transition region, two transitions are seen, the temperatures of which are 65 and 85 °C in the case of a copolymer of acrylonitrile and vinylidene chloride, containing 25 mol-% of vinylidene
    Notes: On a étudié les relaxations observées dans les copolymères statistiques du chlorure de vinylidène avec l'acrylonitrile et le chlorure de vinyle. Ces relaxations correspondant aux transitions vitreuses et sous-vitreuses ont été interprétées a partir de la distribution des séquences, en termes de tétrades pour les premières et de diades pour les relaxations observées dans la zone de transition sous-vitreuse.Dans la zone correspondant à la chute du module que nous assimilons à la zone de transition vitreuse on observe deux transitions dont les températures seraient respectivement 65 et 85 °C pour un copolymère de l'acrylonitrile et du chlorure de vinylidène contenant 25 mol-% de chlorure de vinylidène. Pour les copolymères du chlorure de vinyle et du chlorure de vinylidène la relaxation correspondant à la transition sous vitreuse ß est observée nettement pour une teneur molaire en chlorure de vinyle supérieure à 70%.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1982.051070107
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  • 5
    Electronic Resource
    Electronic Resource
    Copolymères du chlorure de vinylidène avec l'acrylonitrile, le chlorure de vinyle et le méthacrylate de méthyle, 2.Partie 1: cf.4. Fusion  -  utilisation d'un modèle de simulation (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1207-1214 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The melting point depression in vinylidene chloride copolymers, when introducing an increasing number of units B = vinyl chloride, acrylonitrile or methyl methacrylate is studied in this paper. A Monte-Carlo simulation model of chains growing and crystallization is applied and allows to know the proportion Xc of defects in the crystalline phase. An equation given by Sanchez is then applied, and the excess energy ε of the defect created by the incorporation of a B unit in the crystalline vinylidene chloride lattice is calculated.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820420
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  • 6
    Electronic Resource
    Electronic Resource
    Étude de l'état solide des copolymères du chlorure de vinylidène avec le chlorure de vinyle, l'acrylonitrile et le méthacrylate de méthyle, 1. Structure des copolymères, modélisation mathématique en relation avec la structure chimique des chaînes (1981)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 182 (1981), S. 1283-1300 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The properties of a random copolymer are not only determined by composition, but also by the repartition of the monomeric units along the chain. In order to explain the properties of such a copolymer it is necessary to know the sequence distribution or microstructure, each sequence by itself showing structural characteristics: length, relative position, etc. It is thus necessary to conduct a precise synthesis process, and to know the kinetic parameters of the polymerization reaction. Knowledge of the kinetic invariants and monomer feed composition gives access to the theoretical sequence distribution. By different physicochemical methods (NMR, IR and UV spectroscopy), the results obtained by calculation are confirmed. Specifically the effect of microstructure and composition on the properties of some vinylidene chloride (VDC) copolymers with acrylonitrile (AN), vinyl chloride (VC) and methyl methacrylate (MMA) is studied. VDC leads to a very cristalline polymer, whereas PVC generally shows very poor cristallinity, and PAN shows particular structural characteristics. VDC copolymers can easily crystallize when they are rich in VDC. Generally the polymers are semi-crystalline with an amorphous phase. A theoretical model accounting for the lamellar structure and crystallinity of VDC copolymers is described. It utilizes the microstructural data, obtained by a kinetic study and some simple hypotheses, among them the possibility for molecules to slide along each other. This sliding brings together the material which is crystallizable in determined areas. It is thus possible to explain the presence of crystallinity peaks, or at least of paracrystallinity, up to a relatively high amount of comonomer MMA, AN and especially VC in the diffractograms of VDC copolymers with MMA, AN and VC. The paracrystalline domains are defined as areas which can present some degree of order at great distance, with a relatively high amount of comonomer defects.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1981.021820427
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  • 7
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    Conceptual framework and interdisciplinary approach for the sustainable management of gravel-bed rivers: The case of the Drôme River basin (S.E. France) (2009)
    Springer
    Details
    Publication Date: 2009-10-01
    Print ISSN: 1015-1621
    Electronic ISSN: 1420-9055
    Topics: Biology
    Published by Springer
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  • 8
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    Influence of riverbank stabilization techniques on taxonomic and functional macrobenthic communities (2017)
    Springer
    Details
    Publication Date: 2017-10-10
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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  • 9
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    Variability of water temperature may influence food-chain length in temperate streams (2013)
    Springer
    Details
    Publication Date: 2013-08-04
    Print ISSN: 0018-8158
    Electronic ISSN: 1573-5117
    Topics: Biology
    Published by Springer
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  • 10
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    Structural and functional responses of invertebrate communities to climate change and flow regulation in alpine catchments (2019)
    Wiley
    Details
    Publication Date: 2019-03-03
    Description: Understanding and predicting how biological communities respond to climate change is critical for assessing biodiversity vulnerability and guiding conservation efforts. Glacier‐ and snow‐fed rivers are one of the most sensitive ecosystems to climate change, and can provide early warning of wider‐scale changes. These rivers are frequently used for hydropower production but there is minimal understanding of how biological communities are influenced by climate change in a context of flow regulation. This study sheds light on this issue by disentangling structural (water temperature preference, taxonomic composition, alpha, beta and gamma diversities) and functional (functional traits, diversity, richness, evenness, dispersion and redundancy) effects of climate change in interaction with flow regulation in the Alps. For this, we compared environmental and aquatic invertebrate data collected in the 1970s and 2010s in regulated and unregulated alpine catchments. We hypothesized a replacement of cold‐adapted species by warming‐tolerant ones, high temporal and spatial turnover in taxa and trait composition, along with reduced taxonomic and functional diversities in consequence of climate change. We expected communities in regulated rivers to respond more drastically due to additive or synergistic effects between flow regulation and climate change. We found divergent structural but convergent functional responses between free‐flowing and regulated catchments. Although cold‐adapted taxa decreased in both of them, greater colonization and spread of thermophilic species was found in the free‐flowing one, resulting in higher spatial and temporal turnover. Since the 1970s, taxonomic diversity increased in the free flowing but decreased in the regulated catchment due to biotic homogenization. Colonization by taxa with new functional strategies (i.e. multivoltine taxa with small body size, resistance forms, aerial dispersion and reproduction by clutches) increased functional diversity but decreased functional redundancy through time. These functional changes could jeopardize the ability of aquatic communities facing intensification of ongoing climate change or new anthropogenic disturbances.
    Print ISSN: 1354-1013
    Electronic ISSN: 1365-2486
    Topics: Biology , Energy, Environment Protection, Nuclear Power Engineering , Geography
    Published by Wiley
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