1,720,954 research outputs found
Maturation Dynamics of Arcto-Norwegian Cod.
No full textMany commercially important fish stocks are harvested with very high exploitation rates with the consequence of substantial changes in stock parameters as well as reduced harvest rates and, in the worst case, stock depletion. On a long-term the Arcto-Norwegian cod is the most productive cod stock in the world. It has a history of exploitation many hundred of years long and has been heavily exploited since about 1950. The chosen exploitation strategy might have substantial effects on the short-term production of the stock, and a serious question is if a long-term and heavy exploitation may change genetic properties of the stock and hence its reproductive and production potential. In this paper, age and size data of spawning cod, going back to 1932, are analyzed with respect to long-term changes caused by exploitation. During the studied period, average age and size at first spawning have been reduced by about three years and 20 cm. Immature growth has also increased substantially. It is shown that a lot of the variability in age and size at first spawning can be explained by the exploitation itself and, even better, by stock biomass (density dependency). Other factors, like food availability (capelin abundance) and year class strength, also seem to play a role. Due to more or less continuous trends in the data from World War II onwards, it is difficult to disentangle temporal effects (environmental forcing) from other causal agents.
Fluctuation in Stock Properties of Arcto-Norwegian Cod Related to Long-term Environmental Changes.
No full textFrom a historic perspective the cod in the Barents Sea-Svalbard region has been the most productive gadoid stock in the Atlantic. Variation in catches has always been large, but during the last 10-15 years catches and stock abundance have reached the lowest level on record. Three major causes of variation have been discussed; stock reduction through exploitation, environmental influences on recruitment, and species interaction effects on maturation, growth and mortality. In addition, interactions between these three sources might be important. The influence of each specific factor is difficult to evaluate from incidental observations and short-term time series. In that respect, the time series on catches and on biological and environmental information of this stock, which partly goes back to the 19th century assumes a unique position in comparison with data on most other stocks. In this paper fluctuations in catches and stock abundance will be compared with changes in recruitment, size/age composition and growth. This information is discussed in view of historic variation in ecological and environmental parameters. The stock has been under particularly high exploitation pressure since the mid-seventies. Further, large changes in growth rates and poor recruitment to the commercially exploited stock have characteristic for the end of the 1980s and the 1990s. The analysis here shows that substantial long-term variation might underlie short-term variability, and, more importantly, that long-term changes roughly coincide with similar fluctuations in the environment. Consequently, it is suggested that inserting on a steady-state perspective on the population dynamics of this stock may lead to mismanagement and to a reduction of long-term yield.
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
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
- …
