1,721,132 research outputs found
Induction of anti-herbivore defences by direct amphipod consumption and water borne grazer cues in macroalgae
Full text linkDissertação mest., Estudos Marinhos e Costeiros, Universidade do Algarve, 2007Serrão, EsterHerbivores have been repeatedly shown to induce defences in terrestrial plants, but few
examples exist from marine macroalgae. In two bio-assayed laboratory experiments we
tested the effects of (1) direct amphipod consumption, (2) water borne cues from nearby
grazed conspecifics, and (3) water-borne cues from non grazing consumers on the
induction of anti-herbivore defences in macroalgae of the southern coast of Portugal.
Both the brown alga Fucus vesiculosus and the red alga Sphaerococcus coronopifolius
displayed distinct defence regulation. They induced defences when consumers were
present and reduced defences again when consumption ceased. A reduction in
palatability was considered to be indicative of an alga’s defence mechanism. Defence
regulation reacted to consumption stimuli in less than two weeks. For F. vesiculosus we
found the defence activity in the lipophilic fraction of the alga’s chemistry. Both algal
species induce defences after receiving water-borne signals from nearby grazed
conspecifics as well as non-grazing amphipods. These results imply that species of red
and brown algae can recognise a suite of cues indicating herbivore pressure, allowing
them to adjust their defensive traits in finely tuned short-term responses. Inducible
defences may be more common in macroalgae than suspected
The impact of predation on the structuring of Arctic intertidal soft-bottom communities
No full textPredation is a key modifier of community dynamics, but information on its magnitude in community regulation in systematically understudied Arctic coastal habitats is sparse. To test the magnitude and direction of predation effects on the diversity and structure of Arctic benthic communities, we conducted caging experiments in which consumers were excluded from plots at two intertidal sedimentary sites in Svalbard (Longyearbyen and Thiisbukta) for 2.5 months. At the end of the experiment, we took a sediment core from each plot and quantified the total biomass and, separately for each taxon encountered, the number of individuals. At both sites, the exclusion of predators changed the species composition of the communities, but had negligible effects on biomass, total abundance, species richness, evenness and Shannon index. In addition, we found spatial variability and artifact effects at both sites on several response variables
Identifisering av arter i fjæra med digitale verktøy. En mixed methods undersøkelse om hvordan elever bruker og lærer arter i fjæra med Artsapp og Artsorakelet.
Full text linkDenne studien hadde to formål. Det første var å videreutvikle en app slik at den kunne brukes av ungdomsskoleelever til å identifisere de vanligste artene i fjæra. Det andre formålet var å undersøke hvordan elever brukte forskjellige apper i identifikasjonsarbeidet. Det ble gjennomført en 60 min undervisningsøkt med 17 elever i 10. årstrinn om arter i fjæra. Økten inkluderte en førtest og spørreskjema, med en ettertest en uke senere. Appene som ble sammenlignet var Artsoraklet som bruker kunstig intelligens for å gjenkjenne bilder og Artsapp som bruke nøkling. Nøkkelen i artsapp ble selv utviklet for dette prosjektet.
Etter økten kunne elevene i gjennomsnitt identifisere 2.5 arter mer, men det var ikke en signifikant forskjell basert på appene. Det var en klar forskjell i hvordan elevene gikk frem under indentifiseringen basert på appene. Elevene som brukte Artsapp hadde mer nærkontakt med artene, større fokus på kjennetegn, snakket mer aktivt om dem, men diskuterte derimot lite når de skrev ned kjennetegn. Hos elevene som brukte Artsoraklet hadde mindre nærkontakt med artene og samtalen begynte først etter identifiseringen når de skulle skrive ned kjennetegn. Disse samtalene var ofte generelle, med noen få unntak hvor beskrivelsene av arten bygget på elevers egne erfaringer.
Nøkkelord: Artskunnskap, Apper, Artsapp, Artsorakelet, Fjæra, Ungdomsskol
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
Diversity and density of individuals in a predator exclusion experiment in Longyearbyen, Svalbard
No full textSpecies richness and individual abundance for each species in the predator exclusion experiment in the Longyearbyen intertidal, Svalbard during 2017. The file specifies species and abundance per species (columns) in four treatments: Start (start of experiment), Artefact (artefact), Contro/End (manipulation-free areas) and Exclusion (predator exclusion) (rows)
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