1,721,396 research outputs found
Begon, M., Harper, J.L. & Townsend, C.R. — Ecology, Individuals, populations and communities. Blackwell, Oxford, 1986
No full textBourlière François. Begon, M., Harper, J.L. & Townsend, C.R. — Ecology, Individuals, populations and communities. Blackwell, Oxford, 1986. In: Revue d'Écologie (La Terre et La Vie), tome 42, n°2, 1987. p. 205
Cowpox virus infection in natural field vole Microtus agrestispopulations: significant negative impacts on survival
Full text link1. Cowpox virus is an endemic virus circulating in populations of wild rodents. It has been implicated as a potential cause of population cycles in field voles Microtus agrestis L., in Britain, owing to a delayed density-dependent pattern in prevalence, but its impact on field vole demographic parameters is unknown. This study tests the hypothesis that wild field voles infected with cowpox virus have a lower probability of survival than uninfected individuals. 2. The effect of cowpox virus infection on the probability of an individual surviving to the next month was investigated using longitudinal data collected over 2 years from four grassland sites in Kielder Forest, UK. This effect was also investigated at the population level, by examining whether infection prevalence explained temporal variation in survival rates, once other factors influencing survival had been controlled for. 3. Individuals with a probability of infection, P(I), of 1 at a time when base survival rate was at median levels had a 22.4% lower estimated probability of survival than uninfected individuals, whereas those with a P(I) of 0.5 had a 10.4% lower survival. 4. At the population level, survival rates also decreased with increasing cowpox prevalence, with lower survival rates in months of higher cowpox prevalence. 5. Simple matrix projection models with 28 day time steps and two stages, with 71% of voles experiencing cowpox infection in their second month of life (the average observed seroprevalence at the end of the breeding season) predict a reduction in 28-day population growth rate during the breeding season from λ = 1.62 to 1.53 for populations with no cowpox infection compared with infected populations. 6. This negative correlation between cowpox virus infection and field vole survival, with its potentially significant effect on population growth rate, is the first for an endemic pathogen in a cyclic population of wild rodents
Effect of trunk sagittal attitude on shoulder, thorax and pelvis three-dimensional kinematics in able-bodied subjects during gait
Full text linkIt has been shown that an original attitude in forward or backward inclination of the trunk is maintained at gait initiation
and during locomotion, and that this affects lower limb loading patterns. However, no studies have shown the extent to
which shoulder, thorax and pelvis three-dimensional kinematics are modified during gait due to this sagittal inclination
attitude. Thirty young healthy volunteers were analyzed during level walking with video-based motion analysis. Reflecting
markers were mounted on anatomical landmarks to form a two-marker shoulder line segment, and a four-marker thorax
and pelvis segments. Absolute and relative spatial rotations were calculated, for a total of 11 degrees of freedom. The
subjects were divided into two groups of 15 according to the median of mean thorax inclination angle over the gait cycle.
Preliminary MANOVA analysis assessed whether gender was an independent variable. Then two-factor nested ANOVA was
used to test the possible effect of thorax inclination on body segments, planes of motion and gait periods, separately. There
was no significant difference in all anthropometric and spatio-temporal parameters between the two groups, except for
subject mass. The three-dimensional kinematics of the thorax and pelvis were not affected by gender. Nested ANOVA
revealed group effect in all segment rotations apart those at the pelvis, in the sagittal and frontal planes, and at the pushoff.
Attitudes in sagittal thorax inclination altered trunk segments kinematics during gait. Subjects with a backward thorax
showed less thorax-to-pelvis motion, but more shoulder-to-thorax and thorax-to-laboratory motion, less motion in flexion/
extension and in lateral bending, and also less motion during push-off. This contributes to the understanding of forward
propulsion and sideways load transfer mechanisms, fundamental for the maintenance of balance and the risk of falling
Begon, M., Townensend, C. R. & Harper, J. L. — Ecology. From individuals to ecosystems. 4e édition. Blackwell Publishing, Malden, Oxford & Carlton. 2005
No full textErard Christian. Begon, M., Townensend, C. R. & Harper, J. L. — Ecology. From individuals to ecosystems. 4e édition. Blackwell Publishing, Malden, Oxford & Carlton. 2005. In: Revue d'Écologie (La Terre et La Vie), tome 60, n°4, 2005. p. 383
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
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
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
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