1,721,025 research outputs found
The role of phytoplankton in the diet of the bladderwort Utricularia australis R.Br. (Lentibulariaceae)
No full textIt is becoming more apparent that the aquatic carnivorous plants Utricularia (Lentibulariaceae) can capture and utilise a wide range of small aquatic organisms. Although they can take up nutrients directly from the water by rootless shoots, much of their overall nutrition comes from prey caught in their traps. Most of the early literature was focused mainly on animal prey, hence the term carnivorous to describe Utricularia spp., but more recently the contribution of other microorganisms and detritus to their diet is being realised. Specifically, the importance of the phytoplankton in traps as prey is proving interesting. However, most investigations have focused on the trap communities with few comparisons to phytoplankton as potential prey, which could reveal the occurrence of feeding selectivity. The eurytopic species Utricularia australis was surveyed across 12 sites in central Italy in lentic waterbodies ranging from oligotrophic to eutrophic. Phytoplankton communities outside the traps were composed of 135 taxa from 21 orders belonging to eight phyla and the algal community in the traps comprised 124 taxa from 17 orders belonging to eight phyla, recorded from all sampling sites. Among the 12 sites phytoplankton communities were highly diverse; however, communities inside and outside the traps at each site were very similar. This similarity indicated that feeding was not selective. Algal movements are not able to elicit a trap response, yet around 70% of the traps contained phytoplankton only (no animal prey). Therefore, regular spontaneous trap firing, known to occur in U. australis, is thought to be responsible for the similarities in trap and plankton algal communities. At two sites, a Euglenophyte (Lepocinclis sp.) and a Cryptophyte (Chilomonas sp.) proliferated, which were otherwise very rare in the phytoplankton community. This is indicative of favourable growth conditions in the traps and possibly of commensal relationships. It seems that the diet requirements of U. australis are met by having a highly varied prey spectrum
Nickel tolerance and phytoremediation potential of the aquatic plant Lemna minuta and the cyanobacterium Trichormus variabilis in monoculture and consortium
No full textOne of the main threats to aquatic conservation is heavy metal pollution, with nickel (Ni) among the most significant contaminants. The Ni tolerance and remediation potential of Lemna minuta (vascular plant) and Trichormus variabilis (cyanobacterium) in contaminated water were investigated. The phytotoxic effects of nickel sulfate (NiSO4·7 H2O; 6.47 mg/L) on these two species, were assessed after 7- and 14-days exposure by measuring morphological changes, growth (fresh weight) and key physiological parameters (chlorophyll, malondialdehyde, protein content and catalase activity). The ability of L. minuta and T. variabilis to remove Ni was compared in both monoculture (single species) and consortium (mixed species) by measuring the reduction in Ni concentration in the culture medium. Nickel exposure induced phytotoxic effects in both species, as shown by decreases in fresh weight, chlorophyll and protein content, and increases in malondialdehyde content and catalase activity. These effects were more pronounced in monocultures, particularly in T. variabilis, compared to consortia. Lemna minuta exhibited good Ni tolerance and remediation capacity, removing 75 % and 86 % of the metal from the solution after 7 and 14 days, respectively. Trichormus variabilis removed 36 % and 27 % of the Ni after the same exposure time. Consortia exhibited high Ni removal, reaching 80 % and 90 % after 7 and 14 days, but this was not statistically different to L. minuta monocultures. These results demonstrate the potential of L. minuta in the remediation of Ni-contaminated waters and suggest that consortia might enhance the tolerance and viability of both species under Ni-stress
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
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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