1,720,968 research outputs found
Student decision-making about a globally familiar socioscientific issue: the value of sharing and comparing views with international counterparts
No full textThis paper focuses on the views of 16–17-year-old science students from England, Germany, Hong Kong and Sweden on whale hunting, and their perceptions of the views of their international counterparts. The students were all provided with the same decision-making task, discussed the issue in small groups and then presented their views on video, which were shared with their counterparts. The findings show that the decision-making task served to deepen and modify students’ views across all nationalities, and the students generally valued and learned from the sharing of views with students of the same age from around the world. However, an important discovery was that the German students’ opinions often ran counter to those from the other 3 locations, and the paper cautions against making broad-sweeping generalisations about students’ views on socioscientific issues
Different earthworm ecological groups interactively impact seedling establishment
No full textThere is increasing evidence that direct interactions between earthworms and seeds impact the assembly of plant communities. However, effects of earthworms of different ecological groups and their interactions on plant germination and establishment are little known. We set up a full-factorial greenhouse experiment in order to explore impacts of different ecological groups of earthworms (epigeic, endogeic and anecic) on the establishment of seedlings. The three ecological groups of earthworms affected seedling establishment in an interactive way with the effects varying in time. While anecic earthworms detrimentally affected the number of established seedlings, impacts of epigeic and endogeic species depended on the presence of earthworms belonging to other ecological groups. Impacts of anecic earthworms were more significant and consistent than those of epigeic and endogeic ones pointing to the dominance of the effect of anecic earthworms for seedling establishment. The initial positive effect of the combined presence of epigeic and endogeic earthworms compared to treatments with only endogeic and only anecic earthworms was likely due to the acceleration of seed germination and elevated nutrient availability for seedlings in earthworm casts. By contrast, reduced numbers of seedlings in presence of both epigeic and endogeic earthworms compared to the control treatment might have been due to seedling predation after the litter layer had disappeared. The results extend current knowledge on interactions between earthworms and seeds by showing that, in addition to anecic species, also epigeic and endogeic species influence seedling establishment with their effect depending on the presence of anecic species. Moreover, the results indicate that impacts of earthworms vary with the developmental stage of seedlings highlighting the importance of interactions between earthworms and seeds. (C) 2010 Elsevier Masson SAS. All rights reserved.German Research Foundation (DFG) [FOR 456
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
In situ effects of elevated CO2 on plants and insects
Full text link10.1 Mature trees in a CO2 enriched world
Mature (app. 100 years old) temperate forest trees were exposed to an increased
atmospheric CO2 concentration for four growing seasons at the Swiss Canopy Crane site
(SCC) near Basel (Switzerland) using web-FACE (Free air CO2 enrichment) technology.
For 11 trees (5 different species) in elevated CO2 and 26 control trees growing at ambient
CO2 I documented seasonal phenology, measured basal area (BA) increment, main and
lateral shoot growth, leaf area/shoot length ratio and calculated a branching index. At the
end of 2001, one year after the onset of the experiment, I found a significant BA growth
stimulation in Fagus growing in elevated CO2. Fagus exhibited a second significant BA
stimulation in 2003, when Europe experienced a centennial drought (no response in 2002
and 2004). None of the other species showed a stem growth response to CO2 in any of the 4
years. Also when tested across all species, BA increment did not show a significant
response to elevated CO2 (neither when tested per year nor cumulative for four years). The
inclusion of Prunus and Tilia did not change the picture. Fagus showed a significant higher
lateral branching in elevated CO2 in 2002 when shoots developed from buds that were
formed during the first season of CO2 enrichment (2001). The effect disappeared in 2003.
In Quercus, there was a steady increase in leading shoot length in high CO2 trees resulting
in longer leading shoots after 4 years of CO2 enrichement. Phenology (bud break, leaf fall,
leaf duration) was highly species-specific and did not reveal a consistent effect of elevated
CO2. Our four-year data set reflects a highly dynamic and species-specific response of tree
growth to a step change in CO2 supply. In spite of some transient growth stimulation our
results do not support the notion that mature forest trees will grow better in a CO2 enriched
world and thus act as carbon sinks.
10.2 Plant-insect interaction in a CO2 enriched world
I studied two insect species feeding on in situ CO2 enriched plants at treeline. Miramella
alpina fed on two Vaccinium species and Zeiraphera diniana on Larix decidua shoots. In
both plant species elevated CO2 reduced nutritional quality, which affected the
performance of the insects feeding on them. Relative growth rates of Miramella were lower
in animals feeding on V. myrtillus compared to those feeding on V. uliginosum and
grasshoppers growth was affected by elevated CO2 depending on plant species and
nymphal development stage. Relative growth rate of Miramella correlated with CO2
induced changes in leaf water, nitrogen, and starch concentrations, depending on
grasshoppers' instar. Elevated CO2 resulted in reduced female adult weight; irrespective of
plant species elevated CO2 prolonged development time in animals feeding on V.
uliginosum only, but did not cause a significant difference in nymphal mortality. Newly
molted adults of Miramella produced lighter eggs and less secretion, (serving as egg
protection) under elevated CO2. When grasshoppers had a choice among four different
plant species grown either under ambient or elevated CO2, the consumption of V. myrtillus
and V. uliginosum leaves increased under elevated CO2 in females while it decreased in
males compared to ambient CO2-grown leaves. These findings suggest that rising
atmospheric CO2 distinctly affects leaf chemistry in two important dwarf shrub species at
the alpine treeline, leading to changes in feeding behaviour, growth, and reproduction of
the most important insect herbivore in this system.
The study of Zeiraphera (larch bud moth) revealed that larvae grew slower under elevated
CO2 compared to ambient CO2 when trees had remained undefoliated in the previous year.
If, however, trees had been defoliated, this response was reversed, with a faster growth of
larch bud moth on high CO2-exposed trees than on control trees. Pupal weight was not
affected by either CO2 or defoliation. Thus elevated CO2 and defoliation had only minor
effects of larch bud moth performance. Needle maturation over the course of the season
incurres significant compositional changes. N concentration was on average 38% lower and
lignin concentration 55% higher in early July than in mid June 2003. In conclusion, my
results suggest that elevated CO2 and defoliation induced changes in larch needle quality
have only little impact on larch bud moth performance at the alpine treeline, and, in
particular, indicate no reinforced negative effect of these two factors. However, the
pronounced changes of needle quality during needle maturation might suggest that any
shifts in tree phenology due to global change may be of greater importance for alpine larch
bud moth populations than the direct impact of CO2 on needle quality.
An increasing number of studies suggest that switching of host plants due to rising
atmospheric CO2 concentrations is probable (Goverde and Erhardt 2003, Hättenschwiller
and Schafellner 2004, Agrell et al. 2005). However all the experimental work on effects of
elevated CO2 on insect herbivores compares insects in ambient CO2 conditions and insects
feeding on plants, which have been abruptly subjected to the chosen elevated CO2 levels.
One fundamental point, which enables insects to switch host plants, is the degree of insect
mobility. A priori it would be presumed that nymphs are less mobile than adults, but this
was never experimentally tested. I showed that for example caterpillar or grasshopper
nymphs do not switch between tree species or even trees during their larval stages. The
poorer food quality becomes with rising CO2 concentrations the higher might be the need
to switch feeding plants in the future. However, the change in leaf chemistry as well as
related changes in insect behaviour (e.g. switching host plants for feeding or egg
deposition) will occur gradually. It is not known, whether adaptions of insect-plant
relations will occur over the next decades (Whittaker 1999, 2003).
10.3 Conclusion
This work revealed insight into a number of biotic influences of elevated CO2 under most
realistic experimental conditions. Across all tests it became clear that atmospheric CO2-
enrichment exerts rather subtle influences all related to biodiversity.
The major conclusion of my growth analysis in a mature deciduous forest is that after four
years these tall trees do not respond to elevated CO2 with more stem growth. If there is a
sustained response it would be small and much longer observation periods would be needed
to identify such a response, and it is almost certain that such responses will be species
specific as they were during the starting phase of this experiment. From what I see at the
Swiss forest FACE site, a first approximation would be that there is no gain in carbon
stocking in a CO2 rich future in such trees. A smaller CO2 responsiveness of larger, more
complex test systems was already obvious as CO2 research switched from seedlings (pots)
to saplings (open top chambers), a trend now finding strong support by data from the tallest
and oldest forest studied so far under free air CO2 enrichment. My plant-animal interaction
studies with plant material grown in situ under elevated CO2 are in line with other studies,
but do not permit a simple generalizing conclusion. I showed that food plant species matter
and even the sex of the feeding animals played a role. Performance of both insect species is
likely to become impaired by rising CO2 concentration. However, the overall picture is
highly complex.
Scientist are now beginning to study the effects of elevated CO2 on plants and insects in
"natural" (e.g. FACE experiments) systems although they have to deal with a lot more
variability compared to earlier works in controlled conditions, which makes the analysis
more difficult. So far, too little attention was put on species specifity although evidence is
emerging that generalisation of effects found in plants, as well as in insects is not possible
because they show distinct species specific reactions to elevated CO2, as I have shown in
my thesis
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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