1,720,961 research outputs found
Microbiome at the land-sea interface : influence of variable river inputs on coastal communities from daily to pluri-secular scales
No full textCette thèse s’est intéressée à l’étude du continuum terre-mer en analysant des impacts fluviatiles sur la variabilité spatio-temporelle des communautés microbiennes de l’écosystème côtier. L’association entre les changements de structure de ces communautés, évalués par séquençage d’ADN environnemental, et différents paramètres physiques, chimiques, biologiques et géologiques a permis de mieux comprendre la dynamique des écosystèmes côtiers face aux perturbations naturelles et humaines à des échelles variables de temps et d’espace. La Nouvelle-Calédonie, avec son climat subtropical, aux saisons contrastées, ses sols riches en métaux, et des pressions humaines spécifiques, a été choisie comme laboratoire naturel pour étudier des impacts fluviaux variables. Les résultats révèlent que l’influence de facteurs naturels (e.g., cyclones, géologie des bassins versants) génèrent des communautés microbiennes spécifiques qui pourraient être utilisées comme traceurs de ces impacts et démontrent d’une forte connectivité entre les écosystèmes terrestres et côtiers. Cette connectivité peut être amplifiée par les activités humaines, comme l’exploitation pluriséculaire d’une mine de nickel. Les modifications de la composition et de la quantité des apports sédimentaires ont engendré des changements jusqu’à présent pérennes des communautés microbiennes. Cette thèse combine ainsi des approches multi-échelles et multidisciplinaires pour développer une vision holistique de l’écosystème côtier en lien avec l’environnement terrestre. Les résultats promeuvent la mise en place de systèmes de gestion et de conservations de ces écosystèmes fragiles faces aux pressions anthropiques et naturelles croissantes.This thesis focuses on the study of the land-sea continuum and in particular the analysis of river impacts on the spatio-temporal variability of microbial communities in the coastal ecosystem. The association between changes in the structure of these communities, assessed by environmental DNA sequencing, and different physical, chemical, biological and geological parameters has madeit possible to better understand the dynamics of coastal ecosytems in the face of natural and human disturbances on variable spatiotemporal scales. New Caledonia, with its subtropical climate, with contrasting seasons, its soils rich in metals, and specific human pressures, was chosen as a natural laboratory to study variable river impacts. The results reveal that the influence of natural factors such as cyclones and watershed geology generate specific microbial communities that could be used as tracers of these impacts and demonstrate strong connectivity between terrestrial landscapes and coastal ecosystmes. Huamn activity excerbates this link. The centuries-old exploitation of a nickel mine has shown that modifications in the composition and quantity of sediment inputs due to mining activity have generated hitherto invariant changes in microbial communities. This thesis combines multi-scale and multidisciplinary approaches to develop a holistic vision of the coastal ecosystem with its link with the land. The results promote the establishment of management and conservation systems for these fragile ecosystems in the face of increasing anthropogenic and natural pressures
Le microbiome à l'interface terre-mer : l'influence d'apports fluviaux variables sur la structuration des communautés côtières à l'échelle journalière à pluriséculaire
No full textThis thesis focuses on the study of the land-sea continuum and in particular the analysis of river impacts on the spatio-temporal variability of microbial communities in the coastal ecosystem. The association between changes in the structure of these communities, assessed by environmental DNA sequencing, and different physical, chemical, biological and geological parameters has madeit possible to better understand the dynamics of coastal ecosytems in the face of natural and human disturbances on variable spatiotemporal scales. New Caledonia, with its subtropical climate, with contrasting seasons, its soils rich in metals, and specific human pressures, was chosen as a natural laboratory to study variable river impacts. The results reveal that the influence of natural factors such as cyclones and watershed geology generate specific microbial communities that could be used as tracers of these impacts and demonstrate strong connectivity between terrestrial landscapes and coastal ecosystmes. Huamn activity excerbates this link. The centuries-old exploitation of a nickel mine has shown that modifications in the composition and quantity of sediment inputs due to mining activity have generated hitherto invariant changes in microbial communities. This thesis combines multi-scale and multidisciplinary approaches to develop a holistic vision of the coastal ecosystem with its link with the land. The results promote the establishment of management and conservation systems for these fragile ecosystems in the face of increasing anthropogenic and natural pressures.Cette thèse s’est intéressée à l’étude du continuum terre-mer en analysant des impacts fluviatiles sur la variabilité spatio-temporelle des communautés microbiennes de l’écosystème côtier. L’association entre les changements de structure de ces communautés, évalués par séquençage d’ADN environnemental, et différents paramètres physiques, chimiques, biologiques et géologiques a permis de mieux comprendre la dynamique des écosystèmes côtiers face aux perturbations naturelles et humaines à des échelles variables de temps et d’espace. La Nouvelle-Calédonie, avec son climat subtropical, aux saisons contrastées, ses sols riches en métaux, et des pressions humaines spécifiques, a été choisie comme laboratoire naturel pour étudier des impacts fluviaux variables. Les résultats révèlent que l’influence de facteurs naturels (e.g., cyclones, géologie des bassins versants) génèrent des communautés microbiennes spécifiques qui pourraient être utilisées comme traceurs de ces impacts et démontrent d’une forte connectivité entre les écosystèmes terrestres et côtiers. Cette connectivité peut être amplifiée par les activités humaines, comme l’exploitation pluriséculaire d’une mine de nickel. Les modifications de la composition et de la quantité des apports sédimentaires ont engendré des changements jusqu’à présent pérennes des communautés microbiennes. Cette thèse combine ainsi des approches multi-échelles et multidisciplinaires pour développer une vision holistique de l’écosystème côtier en lien avec l’environnement terrestre. Les résultats promeuvent la mise en place de systèmes de gestion et de conservations de ces écosystèmes fragiles faces aux pressions anthropiques et naturelles croissantes
Inferring European coastal ecosystem evolutions during the Anthropocene by paleoecology
No full textInternational audienc
Inferring European coastal ecosystem evolutions during the Anthropocene by paleoecology
No full textInternational audienc
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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