1,721,067 research outputs found
Hvordan er tap av lam relatert til driftsform og rovdyrtetthet?
Full text linkRovdyr er noe som fascinerer og engasjerer. I den sammenheng er det er gjort uttalige studier av rovdyr, både nasjonalt og internasjonalt. Den norske forvaltingen står ovenfor store utfordringer i det videre arbeidet med norske rovdyr. Mye av disse utfordringene er skapt av at forvaltningen over lengre tid hovedsakelig er blitt styrt av politiske interesser, og i mindre grad av innspill fra ulike faglige miljø. Jeg har ved hjelp av tidligere studier og store mengder innsamlet data fra ulike databaser forsøkt å finne om det er enkelte faktorer som kan forutsi tap av lam på utmark. Tre ulike databaser (Rovbasen, NIJOS’ beitelagsdata og Rovviltobservasjoner 2000-2005) ble koblet sammen til en samlet database som kunne benyttes til ulike statistiske analyser av responsvariablene ”prosent tap lam i rovbasen” og ”prosent tap lam i beitelagsdata”. Disse responsvariablene ble testet opp mot flere ulike prediktorvariabler.
Mine resultater viser at tap av lam til rovdyr er additivt, og at tilstedeværelsen av rovdyr vil fortsette å medføre tap så lenge nye forholdsregler ikke blir tatt for å sikre dyr på beite. Analyser viser at det ikke er noen sterk sammenheng mellom driftsform og tap, og det kan dermed antas at fleste beitelagene og driftsenheter har dyr i god kondisjon. Det var en negativ sammenheng mellom tap og tetthet av sau på beite, noe som blant annet kan være et resultat av økt tilsyn. Tapet av sau økte med maksimalt 2 % poeng i områder med rovdyr i forhold til områder uten rovdyr. Dette er en svak sammenheng som er lett påvirkelig av skjevheter i forhold til data. Ettersom tilstedeværelsen av rovdyr medførte en svak økning i tap, vil fjerning av rovdyr som tapsforebyggende tiltak mest sannsynlig ha en svært begrenset effekt på det totale tapet
The spatial relationship between pelagic fish species in the Barents Sea
Full text linkCapelin (Mallotus villosus) is a pelagic fish species with large interannual stock variations in the Barents Sea ecosystem. Together with polar cod (Boreogadus saida) and juvenile herring (Clupea harengus), it functions as an intermediate link that transfers energy from zooplankton to higher trophic levels. Capelin is a key prey and important as a food resource both to sea birds, sea mammals and other fish species. In late summer capelin perform a feeding migration from the central part of the Barents Sea and into Arctic water masses in the north and east. Earlier studies have shown that this migration is strongly density dependent. In years of high abundance, capelin has a more aggregated spatial distribution and migrate further compared to years of low abundance. In this study I investigate how this density dependent migration might affect the distribution and habitat selection of two competing species; polar cod and herring. I compare two years with contrasting abundance in capelin and investigate the spatial distribution of the three competing species with respect to oceanographic habitat. As predicted, capelin showed a shift in distribution into colder water masses in the year with high abundance. One of my hypotheses, which suggested increased spatial overlap with polar cod in years with high capelin abundance, was supported. On the other hand, no increase in overlap with herring was detected. Neither did I find any significant displacement of polar cod or herring that could be connected to capelin abundance. I suggest that the overlap between polar cod and capelin would increase the opportunity of ecological interactions, as they probably utilize many of the same resources. Possible interactions between capelin and its neighbouring pelagic species were connected to the competitive exclusion principle and ecological niche theories
Lik vinterbeite, ulik produksjon og vektutvikling: Et demografistudie på tamrein (Rangifer Tarandus) i Finnmark
Full text linkTetthetsavhengig næringsmangel som fører til lave vekter og påfølgende minket rekruttering er et velkjent fenomen i reindriften i Finnmark. Forskjeller i vekt og produksjon i reindriften i Norge har blitt forklart med ulikheter i høstingsstrategier og vinterforhold. Imidlertid har det blitt viet mindre oppmerksomhet til hvordan ulike sommerbeiteforhold påvirker reproduksjon og vektutvikling. I dette studiet analyserer jeg data fra en vintersiida som fordeler seg i tre ulike sommerbeitedistrikt for å undersøke hvilke faktorer som kan påvirke vektutvikling og kalveproduksjon hos tamrein. Simler og kalvene deres ble veid om vinteren og våren, kalveproduksjon ble registrert om høsten, og drektighet ble undersøkt gjennom ultralydundersøkelser på våren. Resultatet viser at man vil oppleve forskjeller i både vekt og kalveproduksjon som en følge av ulik sommerbeite og ulike driftsformer. Studiet viser at gjeting, kontroll av rovdyr og kalvingsland er elementer som kan være med på å øke kalveproduksjonen selv med lave vekter og høy tetthet av dyr
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
The mating strategy of female Svalbard reindeer
Full text linkThe mating system of Svalbard reindeer was studied in detail on Nordenskiöld land, Svalbard during the mating season 2007. Little is known about the female mating systems of Svalbard reindeer. The aims of the study were to investigate the composition of harems in relation to male attractiveness, harem size and reproductive history and the associated behaviour of females. The movement patterns of marked females were studied in order to determine whether females stay in one harem throughout the rutting season.
Most of the females observed were in harems, i.e. in mating groups that included males. The majority of the harems were small compared to other reindeer populations. Harems usually consisted of 1-5 females, but up to 19 females were observed in a single harem, and up to five males were associated. With increasing number of females in the harem, the number of males increased, as did the maximum male antler size. This may indicate that antler size is an indirect sign of quality for Svalbard reindeer. Females with a calf at heel were uncommon in harems, suggesting they shortly visit harems to become fertilized. The number of males associated with the harem greatly increased the proportion of time the females spent on energy consuming activities such as running and walking. The frequency of mating behaviour (male-female and female-female interactions) directed towards females increased with increasing number of females in the harem, providing evidence for greater somatic cost for females being in harems.
The movement pattern of the observed females was mostly within the same valley, although some females were re-sighted in the adjacent valleys. The females were mostly re-sighted in harems, varying in size. Our results indicate that harems are dynamic entities in terms of the females attending them
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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