1,721,012 research outputs found
Seasonal and spatial patterns of adult Antarctic krill at the Antarctic Peninsula: insights from a 41 year data analysis
No full textLocating the spawning grounds of Antarctic krill Euphausia superba is key to understanding their population dynamics and managing the commercial krill fishery. In the shelf waters of the Antarctic Peninsula where krill and their fishery are concentrated, a recent relaxation of fishing quotas has meant that locally successful spawning grounds could become increasingly targeted. This study revisits the existing paradigm that in summer, larger adult krill migrate awayfrom these shelf-based fishing grounds, out towards oceanic waters to spawn off the shelf break (>1000 m). Our findings support a seasonal on-shelf division of adult krill, with smaller krill closer inshore. However, contrary to current understanding, our results suggest that 85% of the largest and most fecund >50 mm krill remain on-shelf during the summer spawning season. All adults(>30 mm) were strongly concentrated over the shelf throughout the whole spring–summer–autumn transition, with no evidence for any summer redistribution off-shelf. The Western Antarctic Peninsula (WAP) has strong on-shelf–off-shelf gradients in chlorophyll a and sea surface temperature,and based on generalised additive models, our study suggests that the high food requirement of adult krill, coupled with an oligotrophic off-shelf environment, contributes to the distribution of krill observed at the Antarctic Peninsula. The concentration of large, nutritious krill over the shelf throughout the season may be advantageous to land-based predators but raises concern for the management of fisheries that are becoming increasingly concentrated within the key adult krill habitat along the northern shelf of the WAP
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
Seasonal trophic structure of the Scotia Sea pelagic ecosystem considered through biomass spectra and stable isotope analysis
No full textThe biomass size structure of pelagic communities provides a system level perspective that can be instructive when considering trophic interactions. Such perspectives can become even more powerful when combined with taxonomic information and stable isotope analysis. Here we apply these approaches to the pelagic community of the Scotia Sea (Southern Ocean) and consider the structure and development of trophic interactions over different years and seasons. Samples were collected from three open-ocean cruises during the austral spring 2006, summer 2008 and autumn 2009. Three main sampling techniques were employed: sampling bottles for microplankton (0–50 m), vertically hauled fine meshed nets for mesozooplankton (0–400 m) and coarse-meshed trawls for macrozooplankton and nekton (0–1000 m). All samples were identified to the lowest practicable taxonomic level and their abundance, individual body weight and biomass (in terms of carbon) estimated. Slopes of normalised biomass spectrum versus size showed a significant but not substantial difference between cruises and were between −1.09 and −1.06. These slopes were shallower than expected for a community at equilibrium and indicated that there was an accumulation of biomass in the larger size classes (101–105 mg C ind−1). A secondary structure of biomass domes was also apparent, with the domes being 2.5–3 log10 intervals apart in spring and summer and 2 log10 intervals apart in autumn. The recruitment of copepod-consuming macrozooplankton, Euphausia triacantha and Themisto gaudichaudii into an additional biomass dome was responsible for the decrease in the inter-dome interval in autumn. Predator to prey mass ratios estimated from stable isotope analysis reached a minimum in autumn while the estimated trophic level of myctophid fish was highest in that season. This reflected greater amounts of internal recycling and increased numbers of trophic levels in autumn compared to earlier times of the year. The accumulation of biomass in larger size classes throughout the year in the Scotia Sea may reflect the prevalence of species that store energy and have multiyear life-cycles
Mesoscale zooplankton distribution patterns and euphausiid population ecology in the south-west Atlantic
No full textTwo mesoscale net sampling surveys were conducted in the south-west Atlantic between 34° and 55 °S. The first survey was in the austral spring of 1990 and used both an RMT8 net which was trawled obliquely down to 200 or 300 m and caught mainly macrozooplankton and a Bongo net which was deployed at the surface and sampled mesozooplankton. The second survey was in the austral spring of 1991 and used a Bongo net which was deployed obliquely down to 50 m and sampled mesozooplankton. This thesis considers the species composition and abundance of these samples and represents one of the first insights into the mesoscale biogeography of zooplankton communities in the south-west Atlantic.155 species from 9 taxonomic groups were considered including euphausiids, hyperiid amphipods, chaetognaths, salps, siphonophores, and nektonic/planktonic fish. Multivariate analyses were used to highlight species assemblage distribution patterns and determine strongly correlated environmental variables. In the 1990 RMT8 samples, species assemblages showed a distribution pattern related to the location of water masses, which was reflected in a combination of water mass and latitude being the most strongly correlated environmental variables. In the 1990 Bongo samples, a combination of seasurface temperature and latitude were most strongly correlated environmental variables and different species assemblages showed a pattern of being located in exclusive temperature ranges. The two sample sets did exhibit some common distribution patterns especially in the warm, sub-tropical waters to the north and the Falkland Shelf to the south. However, there were fundamental differences in the mid-latitudes regions, possibly reflecting the reduced ability of larvae to counteract expatriating forces when compared with adults. Further comparisons made between the 1990 and 1991 Bongo sample sets highlighted some of the causal factors behind distribution patterns. For instance, the precise definition of the boundary between sub-tropical and sub-Antarctic assemblages by the 17.3°C isotherm despite the multitude of expatriating phenomena suggested that many organisms were at the edge of their physiological limits in this region. In polar waters, distribution patterns were consistent but temperatures variable suggesting that advection rather than temperature tolerance was more influential. Further data from Montu (1977) and the Discovery Investigations was examined to add a seasonal dimension to the above patterns as well as providing an insight into the importance of population ecology on community distribution. Studies were concentrated on euphausiid species from which it was apparent that size structure and species dominance changed considerably with season. Estimates of the productivity of these species showed that weight-specific rates were comparable with more sub-tropical regions despite biomass levels being proportionally low.The use of satellite thermal images for predicting faunal distribution patterns was assessed with respect to future biogeographic analysis of this region. Images were a good predictor at the sub-tropical boundary but a poor predictor in other regions highlighting the fact that in situ net sampling methods still appear to be the most effective and reliable investigative tools for biogeographic 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
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
- …
