1,721,029 research outputs found
Effort allocation of the Dutch beam trawl fleet
No full textDit proefschift gaat in op de vraag hoe vissers hun activiteiten verdelen in ruimte en tijd. Het begrijpen van de mechanismen die de dynamiek van vissersvloten bepaalt is van belang om te begrijpen hoe vissers reageren op maatregelen in
het kader van visserijbeheer en veranderingen in de omgevingsvariabelen. Deze kennis kan gebruikt worden door visserijbeheerders om effectieve beheersmaatregelen
te ontwerpen. Het onderzoek richt zich op demersale visserijen die een aantal soorten tegelijkertijd exploiteren.
De resulltaten in het proefschrift laten zien dat de visserij reageert op seizoensveranderingen in de ruimtelijke verdeling van hun doelsoorten schol en tong.
Gebiedsspecialisatie en interferentiecompetitie tussen schepen spelen een rol in de totstandkoming van de ruirntelijlce verdeling van de vloot, binnen de beperkingen
die er opgelegd worden door het visserijbeheer. Er is een 'dynamic state variable model' ontworpen om het effect van beperkingen als gevolg van visserijbeheer op de ruirntelijke en temporele verdeling van visserijinspanning
en discarding te bestuderen. Dit model evalueert de trade-offs en beperkingen waar individuele vissers mee geconfronteerd worden in hun visserij.
Beheersrnaatregelen be'invloeden de trade-offs en beperkingen die het individuele gedrag van vissers vormgeven, wat resulteert in veranderingen in de riuimtelijke
verdeling van vissersvloten en andere aspecten van vloot dynamica. In het geval van de boomkorvloot laat het onderzoek zien dat de visserij-inspanning als gevolg van de verlaging van het scholquotum zuidwaarts is verplaartst. Dit
heeft tot gevolg gehad dat er een toename is geweest van de relatitieve vangbaarheid voor tong en jonge schol, en een drijfveer voor vissers om marktwaardige vis te discarden.
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The Information Value of Full-Retention Policies
Full text linkDiscard rates in marine fisheries have been estimated at more than 80% for some individual fisheries, with an average global discard rate of 8%. Discarding of catch can be problematic for three main reasons: (1) in the absence of accurate and precise discards estimates, unreliable catch data distort estimation of the appropriate quotas; (2) bycatch imposes a cost on the resource as survival rates are generally low; and (3) bycatch-induced mortality of charismatic species presents a loss of non-use values. Policy instruments to limit discarding vary from taxes on bycatch, to subsidies for selective fishing gear, to outright bans on discarding, also called full-retention policies. The 2013 reform of the European Union's Common Fisheries Policy features the introduction of such an obligation to land all catches "of species which are subject to catch limits." In this paper we aim to estimate the economic effects of a full retention policy in a mixed fishery. More specifically, we estimate the economic value of the data distortion caused by discarding of fish, and how these economic losses are ameliorated by a ban on discards. We present a bioeconomic model capable of investigating these questions in a mixed fishery for a variety of stock assessment methods, harvest control rules, and discarding policies. We apply the model to the North Sea demersal fishery, focusing on the two main commercial species plaice (pleuronectes platessa) and sole (solea solea). We find that the information value of discard bans depends largely on the prevailing harvest control rule.Keywords: Poor Data and Uncertainty, Fisheries Economics, Modeling and Economic Theor
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
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
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