1,721,003 research outputs found
Natural recruitment contributes to high densities of grass carp Ctenopharyngodon idella (Valenciennes, 1844) in Western Europe
Full text linkIntroductions of grass carp, well known for their potentially negative ecosystem effects, have been performed in several countries around the world.
As the species was considered unable to reproduce naturally under non-native environmental conditions, little attention was initially given to its
invasive potential. We studied an area in northern-Italy where, contrary to expectations, introductions that were performed in the early 80s still exert
a considerable pressure on aquatic macrophytes. In order to reveal whether the observed population dynamics are the result of natural events or
stocking we analysed the density, age- and size-structure of the grass carp population and the migration pathways available to it. Telephone surveys
were also used to check for fish transport from national and international suppliers. We also sampled potential spawning and nursery areas for
young individuals and, when some were captured, we applied stable isotope analyses to discriminate their origin. We found that the population of
large individuals likely originated solely from early stocking. We also documented the first analytical evidence of grass carp recruitment in the
study area and, to our knowledge, in Western Europe. Therefore the species has the potential to become invasive in these areas and more detailed
studies are needed to assess this potential. Further management should account at least for natural recruitment and potential negative environmental
effects, controlling the species where needed.peerReviewe
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
Accumulation of organochlorines in Baltic Sea fishes
No full textItämeri on yksi pahiten organoklooriyhdisteiden (PCB, dioksiinit, furaanit) saastuttamia merialueita. Kertyvinä ja ravintoketjuissa rikastuvina myrkkyinä ne ovat aiheuttaneet vakavia ongelmia Itämeren ravintoverkkojen huippupedoille, kuten hylkeille ja kalaa syöville petolinnuille, ja ovat myös uhka ihmisen terveydelle. Silakan myrkkypitoisuuksissa ei ole havaittu laskua 1980-luvun puolivälin jälkeen, vaikka tuntuvat päästörajoitukset ja yhdisteiden käyttökiellot ovat johtaneet taustapitoisuuksien tasaiseen laskuun Itämeressä aina 1970-luvulta saakka. Itämeren suuren silakan ja sitä syövän lohen myrkkypitoisuudet ylittävät EU:n organoklooriyhdisteille asettaman raja-arvon kaloissa ja kalatuotteissa. Pitoisuuksissa on myös havaittu suurta vaihtelua kalayksilöiden ja merialueiden välillä. Mikko Kiljusen väitöskirja selvittää näiden ilmiöiden taustoja. Kiljunen tutki, voidaanko kalastuksen säätelyllä vaikuttaa silakan myrkkypitoisuuksiin ja kuinka säätelytoimenpiteet vaikuttavat myrkkyjen kertymiseen ihmiseen.Commercially important Baltic Sea fish species such as herring (Clupea harengus L.) suffer from high concentrations of toxic and highly bioaccumulative organochlorines (OCs). This thesis investigates accumulation of these compounds in the Baltic Sea from invertebrates through herring, sprat (Sprattus sprattus (L.)) and three-spined stickleback (Gasterosteus aculeatus L.) into salmon (Salmo salar L.) and onwards to humans. Strategies to reduce present OC concentrations in fish and therefore human intake are also tested. The thesis presents some methodological insights into application of stable isotope analysis, used in accumulation studies. Age and growth seems to explain most of the individual variation in herring OC concentrations. An accumulation model constructed for herring together with empirical data suggested that growth plays a significant role in explaining the differences in OC concentration between sea areas. Changes in herring growth during past decades are the most probable explanation for observations that herring organochlorine concentrations have levelled out. Stable isotopes combined with an accumulation model developed for salmon revealed that individual and spatial variability in salmon OC concentrations arose from the differences in the salmon diet, trophic position, as well as prey OC concentrations and lipid content. Based on the theory of density-dependence in herring growth, the accumulation model combined with age-structured simulations and a probabilistic human intake model showed that concentration in the Baltic herring could be decreased substantially by increased fishing.unknown accessibilityei tietoa saavutettavuudest
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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