1,721,026 research outputs found
A new method to determine the reproductive condition in female tubeworms tested in Seepiophila jonesi (Polychaeta: Siboglinidae: Vestimentifera)
Full text linkVestimentiferan tubeworms are significant members of deep-sea chemosynthetically-driven communities, including hydrothermal vents and cold seeps. The reproductive condition in this taxon is rarely studied because of sampling constraints inherent to these environments, and the lack of a simple methodology to quantify gonad development in vestimentiferans. We demonstrate that the amount of gonad found in the first 10 mm of trunk can be used as representative of the reproductive condition of the individual, and we establish a linear relationship between the amount of gonad and the proportion of wax ester in the trunk of female vestimentiferans. This relationship represents a new method for the determination of the reproductive condition in this group
Phospholipid fatty acids are correlated with critical thermal tolerance but not with critical pressure tolerance in the shallow-water shrimp Palaemon varians during sustained exposure to low temperature
No full textSome extant deep-sea shrimp are known to be descended from shallow-water ancestors that adapted to environmental conditions (constant low temperature and high hydrostatic pressure) in the deep sea. During acclimation to low temperature and high hydrostatic pressure representative of the deep-sea, critical thermal tolerance decreases and critical pressure tolerance increases in the shallow-water shrimp Palaemon varians. It has been suggested that these shifts may depend in part on adjustments to phospholipid fatty acid composition and/or metabolic adjustments. Here, we present evidence that metabolic rate does not change during sustained exposure to low temperature (5°C) in the shallow-water shrimp Palaemon varians, and that metabolic rate and acute environmental tolerances are not correlated during sustained exposure to low temperature, suggesting that standard metabolic rate does not affect acute environmental tolerances. In contrast, we present evidence that phospholipid fatty acid composition does shift during sustained exposure to low temperature. Desaturation of fatty acids during sustained exposure to low temperature supports the suggestion that cell lipid bilayer homeoviscous modifications are important in low temperature acclimation. Shifts in several individual phospholipid fatty acids during sustained low temperature exposure are correlated with critical thermal tolerance. Exploring the greater complexity apparent in the responses of these phospholipid fatty acids to sustained low temperature exposures suggests a potential homeostatic impact moderating adverse impacts on nervous system function. However, shifts in phospholipid fatty acids are not correlated with critical pressure tolerance during exposure to low temperature, suggesting that shifts in critical pressure tolerance are related to modifications other than cell lipid bilayer composition.<br/
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
Seabed foraging by Antarctic krill: Implications for stock assessment, bentho-pelagic coupling, and the vertical transfer of iron
No full textA compilation of more than 30 studies shows that adult Antarctic krill (Euphausia superba) may frequent benthic habitats year-round, in shelf as well as oceanic waters and throughout their circumpolar range. Net and acoustic data from the Scotia Sea show that in summer 2-20% of the population reside at depths between 200 and 2000 m, and that large aggregations can form above the seabed. Local differences in the vertical distribution of krill indicate that reduced feeding success in surface waters, either due to predator encounter or food shortage, might initiate such deep migrations and results in benthic feeding. Fatty acid and microscopic analyses of stomach content confirm two different foraging habitats for Antarctic krill: the upper ocean, where fresh phytoplankton is the main food source, and deeper water or the seabed, where detritus and copepods are consumed. Krill caught in upper waters retain signals of benthic feeding, suggesting frequent and dynamic exchange between surface and seabed. Krill contained up to 260 nmol iron per stomach when returning from seabed feeding. About 5% of this iron is labile, i.e., potentially available to phytoplankton. Due to their large biomass, frequent benthic feeding, and acidic digestion of particulate iron, krill might facilitate an input of new iron to Southern Ocean surface waters. Deep migrations and foraging at the seabed are significant parts of krill ecology, and the vertical fluxes involved in this behavior are important for the coupling of benthic and pelagic food webs and their elemental repositories
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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