1,720,964 research outputs found
First evidence of microplastics ingestion in benthic amphipods from Svalbard
No full textThe present paper provides the first record of ingestion of microplastics in natural context by Gammarus setosus from Svalbard Archipelago. The plastic particles were identified both by Nile Red staining and Micro FT-IR spectroscopy. The species studied ingests microplastic particles in natural conditions if present in its habitat, probably mistaking them as food. The microplastic particles ingested may be available for uptake to predators that consume this Arctic amphipod, producing consequences to the food web
Plastic abundance and seasonal variation on the shorelines of three volcanic lakes in Central Italy: can amphipods help detect contamination?
No full textDespite the exponential increase of studies on plastic debris in recent years, there are still few works focusing on the problem as it relates to inland waters: little is known about the accumulation and dispersion dynamics on lake shores, and there are no standardized sampling methods for monitoring purposes. The accumulation of plastic litter in natural habitats also threatens the resident organisms. In this paper, we investigated the abundance and accumulation of plastic particles, ranging in size from 1 to 50 mm, from the beach sediment of three volcanic lakes in Central Italy: Albano, Bracciano, and Vico. The collection was designed to define the most important variables that one must consider in order to obtain a representative sample of plastic litter in a lake environment. In view of the high heterogeneity of sampling protocols used, comparison among the obtained results is limited and sometimes impossible. By using one of the proposed sampling methodologies, and critically analyzing the results, we aimed to highlight a possible monitoring criterion and to identify specific elements that can be meaningful and representative. The samples were collected in May and September 2017. For each lake, we sampled plastic items and sediments from two beaches. Albano contained the largest amount of plastic (in weight), while Bracciano had the largest number of particles. Our observations lead us to infer that the number of particles is the parameter most sensitive to environmental variations, as well as the more suitable for monitoring with greater definition the differences between sites. Moreover, sampling should be taken in different seasons, following a sampling pattern that includes at least two beaches placed in strategic positions with respect to wind and waves. In order to identify new indicators to evaluate the entry points of plastic into the food web, we collected, from the same sites analyzed, some specimens of the Talitrid Amphipod Cryptorchestia garbinii, a detritivorous species having a critical role in debris turnover of these environments. To investigate the microplastic (MP) ingestion in natural conditions, we analyzed their digestive tracts with both Nile red staining method and micro-FTIR spectroscopy. The analyses confirmed that C. garbinii was able to ingest plastics in natural conditions. Therefore, it can signify one of the entry points for microplastics (MPs) in the trophic chain. This observation constitutes the first evidence of MP ingestion in this species
Preliminary observations on the effect of light and temperature on the hatching success and rate of Lepidurus arcticus eggs
No full textDormancy, which arrests development, is a well-known survival strategy among animals living in the Arctic to overcome harsh periods. It is not clear if the dormant state in notostracans is controlled endogenously (diapause) or exogenously (quiescence). For Lepidurus arcticus, it is unknown how it responds to the photoperiod entrainment, if it has a biological clock and if it has a rhythmic expression of the clock genes. We studied the hatching success of resting eggs at four constant temperatures (5, 10, 15 and 25 °C) and under different illumination regimes [continuous light (LL) and continuous dark (DD)]. It was assumed that light and temperature are both important triggers, with temperature having the most pronounced effect. In our experiment, hatching occurred only at 5 and 10 °C, while we did not observe hatching at 15 and 25 °C. The highest percentage of eggs hatched was at 10 °C in LL (60%); the lowest was at 5 °C in DD (18%). The percentages hatched at 5 °C in LL (24%) and at 10 °C in DD (26%) were similar. Our results indicate that both temperature and light had a significant and interacting effect on hatching in L. arcticus, with temperature being the dominant factor controlling the process. This suggests that changes in temperature affecting the Arctic may significantly impact phenology of this key species in the region. Given that no hatching was observed at 15 °C or above, the persistence of this species may be at risk in areas were arctic lakes are expected to warm to such levels during the summer months
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
- …
