1,720,965 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
A Model for Changes in Germination Synchrony and Its Implements to Study Weed Population Dynamics: A Case Study of Brassicaceae
No full textIn every agricultural system, weed seeds can be found in every cubic centimeter of soil. Weed seeds, as a valuable trait underlying the fate of weed populations, exhibit differing levels of seed dormancy, ensuring their survival under uncertain conditions. Seed dormancy is considered as an innate mechanism that constrains germination under suitable conditions that would otherwise stimulate germination of nondormant seeds. This work provides new insight into changes in germination patterns along the dormant to nondormancy continuum in seeds with physiological dormancy. Notable findings are: (1) germination synchrony can act as a new parameter that quantitatively describes dormancy patterns and, subsequently, weed population dynamics, (2) germination synchrony is dynamic, suggesting that the more dormancy decreases, the more synchrony is obtainable, (3) after-ripening and stratification can function as a synchronizing agent that regulates germination behavior. Freshly harvested seeds of Brassica napus with type 3 of non-deep physiological dormancy showed the most synchronous germination, with a value of 3.14, while a lower level of germination asynchrony was found for newly harvested seeds of Sinapis arvensis with type 1 of non-deep physiological dormancy, with an asynchrony value of 2.25. After-ripening and stratification can act as a synchronizing factor through decreasing the asynchrony level and increasing synchrony. There is a firm relationship between seed dormancy cycling and germination synchrony patterns, ensuring their survival and reproductive strategies. By germinating in synchrony, which is accompanied by cycling mechanisms, weeds have more opportunities to persist. The synchrony model used in the present study predicts germination behavior and synchrony along the dormant to nondormancy continuum in weed seeds with physiological dormancy, suggesting a useful method for the quantification of germination strategies and weed population dynamics
Variations on the Author
Full text link“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
Full text linkWe 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
Study of the development of a community focused strategy on the cost of innovative solutions for small and rural drinking water systems
No full textImperial Users onlyDistinctio
Modélisation numérique du couplage entre l'endommagement et la perméabilité des roches. Application à l'étude des ouvrages de stockage souterrain
No full textThe relation between damage and permeability in rocks is a very important subject in industrial applications. It is for example the case of cracks around the radioactive waste storage galleries (EDZ) which can rise considerably the permeability and so make a serious problem for the sealing and the safety of these structures. The same phenomena can occur in the surrounding concrete wall of the nuclear power stations and also in the cracking of the oil-bearing rocks reservoirs. The experimental research on this subject, specially in laboratory G.3S-LMS in Ecole Polytechnique made it possible to determine the orders of damage effect on the permeability change. But a numerical modeling of these phenomena for setting a constitutive behavior law was to be done. This is the principal objective of this thesis.Le couplage entre l'endommagement et la perméabilité des roches suscite un intérêt grandissant pour des applications industrielles. C'est le cas par exemple du problème de la fissuration autour des galeries (EDZ) de stockage de déchets radioactifs qui peut augmenter considérablement la perméabilité et constituer, de ce fait, un risque sérieux pour l'étanchéité et la sûreté de ces ouvrages. Le même phénomène peut se produire dans le béton des enceintes des centrales nucléaires ainsi que dans les roches réservoirs pétrolifères. Des recherches à caractère expérimental sur ce sujet, particulèrement au laboratoire G.3S-LMS de l'Ecole Polytechnique, ont permis de déterminer les ordres de grandeur de l'effet de l'endommagement sur la perméabilité. Mais une modélisation numérique de ce phénomène permettant d'établir des lois rhéologiques restait à faire, et c'était l'objectif principal de ce travail
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
The role of climate and plant life-history traits as drivers of seed germination niches
No full text<p>The relationship between climate and life-history traits plays a crucial role in defining the ecological niches of plants. By examining the extensive information available in the literature, we can gain a thorough understanding of the factors that shape the germination niches of various seed plant species. Our goal was to explore the global impact of climate and life-history traits on the germination niches of plants using newly assembled, extensive data sets.</p>
Modélisation numérique du couplage entre l'endommagement et la perméabilité des roches. Application à l'étude des ouvrages de stockage souterrain
Full text linkThe relation between damage and permeability in rocks is a very important subject in industrial applications. It is for example the case of cracks around the radioactive waste storage galleries (EDZ) which can rise considerably the permeability and so make a serious problem for the sealing and the safety of these structures. The same phenomena can occur in the surrounding concrete wall of the nuclear power stations and also in the cracking of the oil-bearing rocks reservoirs. The experimental research on this subject, specially in laboratory G.3S-LMS in Ecole Polytechnique made it possible to determine the orders of damage effect on the permeability change. But a numerical modeling of these phenomena for setting a constitutive behavior law was to be done. This is the principal objective of this thesis.Le couplage entre l'endommagement et la perméabilité des roches suscite un intérêt grandissant pour des applications industrielles. C'est le cas par exemple du problème de la fissuration autour des galeries (EDZ) de stockage de déchets radioactifs qui peut augmenter considérablement la perméabilité et constituer, de ce fait, un risque sérieux pour l'étanchéité et la sûreté de ces ouvrages. Le même phénomène peut se produire dans le béton des enceintes des centrales nucléaires ainsi que dans les roches réservoirs pétrolifères. Des recherches à caractère expérimental sur ce sujet, particulèrement au laboratoire G.3S-LMS de l'Ecole Polytechnique, ont permis de déterminer les ordres de grandeur de l'effet de l'endommagement sur la perméabilité. Mais une modélisation numérique de ce phénomène permettant d'établir des lois rhéologiques restait à faire, et c'était l'objectif principal de ce travail
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