1,720,975 research outputs found
Nephrocalcinosis in juvenile farmed Atlantic salmon
No full textEnglish summary
Good health and welfare of farmed fish is crucial for further growth and development of the fish farming industry in Norway and abroad. Systematic work is being done at all levels of the industry with measures that can improve the health and welfare of farmed fish, but there are still some challenges that have not yet been resolved. One of these challenges is nephrocalcinosis or kidney stones. In Norway, it is reported that this, together with hemorrhagic smolt syndrome (HSS), are the most common causes of mortality in hatcheries, before the fish are transferred to sea. Nephrocalcinosis is not common in wild fish, and there is a common consensus that nephrocalcinosis is a production disorder among both fish health personnel, operational personnel and managers, and the research community.
The main aim of this project was therefore to first study the prevalence and severity of nephrocalcinosis in farmed salmon and then look at the health and welfare effects of the production disorder. Since previous studies and experience from the industry have pointed to the tank environment as a risk factor for developing nephrocalcinosis, it was important to investigate the extent to which the condition was linked to various environmental factors. By identifying risk factors linked to the development of nephrocalcinosis, measures can be introduced to prevent or reverse the development of the production disorder and thus contribute to increased health and welfare in farmed fish.Norsk sammendrag
God helse og velferd hos oppdrettsfisk er avgjørende for videre vekst og utvikling av oppdrettsnæringen i Norge og utlandet. Det jobbes systematisk i alle ledd i næringen med tiltak som kan bedre helse og velferd hos oppdrettsfisken, men det er likevel noen utfordringer som ikke er løst. En av disse utfordringene er nefrokalsinose eller nyrestein. I Norge rapporteres det om at dette, sammen med hemorragisk smoltsyndrom (HSS) er vanligste årsakene til dødelighet i settefiskfasen, før fisken flyttes over i sjø. Nefrokalinose er ikke vanlig hos villfisk, og det er en felles forståelse for at nefrokalsinose er en produksjonslidelse hos både næringsaktører, fiskehelsepersonell og forskningsmiljø.
Hovedmålet med denne oppgaven var derfor å først kartlegge utbredelsen og alvorlighetsgraden av nefrokalsinose hos oppdrettslaks for deretter å se på helse- og velferdseffekter av produksjonslidelsen. Siden tidligere studier og erfaring fra næringen har pekt på karmiljøet som risikofaktor for nefrokalsinose var det viktig å undersøke i hvilken grad tilstanden var knyttet til ulike miljøfaktorer. Ved å identifisere risikofaktorer knyttet til utvikling av nefrokalsinose kan man innføre tiltak for å forebygge eller reverse utvikling av produksjonslidelsen og dermed bidra til økt helse og velferd hos oppdrettsfisk
Turnover of trophic markers and lipid carbon in Arctic marine food webs : the contribution of key zooplankton species
Full text linkIn the context of climate warming, severe shifts in the phyto- and zooplankton communities, and thus changes in trophic interactions, are expected. It is therefore essential to better understand the lipid and fatty acid turnover in the in the lipid-driven Arctic food web. This study aims at evaluating the role of zooplankton in the transfer of lipids from primary producers to higher trophic levels. It combines field observations and experimental work to fill the gaps of knowledge in the ecology and lipid biochemistry of Arctic zooplankton key species, i.e. the copepods Calanus glacialis, Pseudocalanus minutus and Oithona similis, the thecosome pteropods Limacina helicina and L. retroversa and the gymnosome pteropod Clione limacina
Assimilation rates, compound-specific stable isotope analysis and fatty acid data of dominant Antarctic copepods
No full textCopepod samples were taken during the Antarctic expedition PS 79 (ANT XXVIII/2) with RV Polarstern (Cape Town – Cape Town, 3 Dec 2011 – 5 Jan 2012). Copepods were collected at Station 53 (60° 3.22'S, 0° 2.14' E) in the Antarctic Weddell Gyre on 28 December 2011 by vertical bongo net hauls down to 300 m depth. Specimens of C. acutus (210 copepodids CV and 160 females) and of C. propinquus (125 females, no CV stages available) were gently sorted from the catch, maintained alive in filtered seawater at 0°C in a cooling container on board and transported to Germany at 0°C by airplane. Feeding carbon-labelled diatoms to these copepods during 9 days of feeding ,13C elucidated assimilation and turnover rates of copepod total lipids as well as specific fatty acids and alcohols. The 13C incorporation into these compounds was monitored by compound-specific stable isotope analysis (CSIA). The differences in lipid assimilation and turnover clearly show that the copepod species exhibit a high variability and plasticity to adapt their lipid production to their various life phases
Umsatz von trophischen Markern und Lipidkohlenstoff in arktischen marinen Nahrungsmittelbahnen
No full textIn the context of climate warming, severe shifts in the phyto- and zooplankton communities, and thus changes in trophic interactions, are expected. It is therefore essential to better understand the lipid and fatty acid turnover in the in the lipid-driven Arctic food web. This study aims at evaluating the role of zooplankton in the transfer of lipids from primary producers to higher trophic levels. It combines field observations and experimental work to fill the gaps of knowledge in the ecology and lipid biochemistry of Arctic zooplankton key species, i.e. the copepods Calanus glacialis, Pseudocalanus minutus and Oithona similis, the thecosome pteropods Limacina helicina and L. retroversa and the gymnosome pteropod Clione limacina
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
Effect of food and light on the development of the Arctic copepod Calanus glacialis during the winter-spring transition
No full textWe investigated potential impacts of earlier sea ice retreat and timing of the spring bloom on overwintering copepodites (CIV) of Calanus glacialis, the main primary consumer in Arctic shelf seas. By field studies and laboratory experiments, we following the feeding and growth of C. glacialis under different light (dark/light) and food (starved/fed) conditions, spring 2013, in high-Arctic Svalbard. We carefully monitored the molting rate, lipid content and fatty acid composition in field and laboratory specimens, simultaneously, over a 2 months period. Field results indicated that CIV were in dormancy (diapause) until the light returned. Both light and food appeared to be important “wake-up” triggers from diapause. Growth and development, however, were strongly regulated by food. In field, the main molting from CIV to CV occurred 2-3 weeks after the onset of the spring bloom (June) which corresponded well with the experimental results where the fed ones molted end of April after 3 weeks of intensive feeding, while the starved ones not. Our results suggest that C. glacialis quickly respond to external cues, being able to adapt to a changing Arctic
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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