1,720,963 research outputs found
Pelophylax lessonae embryos: a valid model for the study of muco-ciliary epithelia and for testing the effects of zerovalent iron, nickel and cobalt nanoparticles
No full textThe assessment of potential risk of emerging xenobiotics requires the use of good experimental models, to evaluate the effects on both health and ecosystems. The effects of engineered metal nanoparticles (ENPs) of iron, nickel and cobalt were tested on the embryos of the frog Pelophylax lessonae at Gosner developmental stage 21, to validate this species as an experimental model for ecotoxicological studies. Through microscopic investigations (light, SEM, TEM) the embryonic epithelium were characterized, since they are the first interface exposed to environmental pollutants, and five cell types have been identified: basal cells, ciliated cells, goblet cells, small secretory cells (SSCs) and ionocytes. Treatments with ENPs showed significant retard in growth and developmental stages and several malformations were observed such as abnormally large ventral mass, bent body axe, head malformation and underdeveloped or absent eyes. At epidermal level, an increase in the volume of ciliated cells, goblet cells and SSCs was observed. The number of exocytosis vesicles in mucus-secreting cells was increased. Besides, modifications of fucosylation and sulfation were detected in epidermal mucins, altering the protective role and function of cilia in the ciliated cells. The number of mitoses in the basal cells was increased, and mitotic processes were also observed in specialized goblet cells. At the ultrastructural level, enlarged intercellular spaces were observed and ciliated cells presented sticked cilia and mitochondrial swelling.La valutazione del potenziale rischio di xenobiotici emergenti, richiede l'uso di buoni modelli sperimentali per valutare gli effetti sia sulla salute che sugli ecosistemi. Gli effetti delle nanoparticelle metalliche ingegnerizzate (ENP) di ferro, nichel e cobalto sono stati testati sugli embrioni della comune rana verde Pelophylax lessonae, allo stadio di sviluppo 21 di Gosner, per validare questa specie come modello sperimentale per studi ecotossicologici. Attraverso indagini in microscopia ottica ed elettronica (SEM, TEM) è stato caratterizzato l'epitelio embrionale, in quanto prima interfaccia esposta agli inquinanti ambientali, e sono stati identificati cinque tipi di cellule: cellule basali, cellule ciliate, cellule caliciformi, piccole cellule secernenti (SSC) e ionociti. I trattamenti con ENP hanno mostrato un ritardo significativo nelle fasi di crescita e sviluppo embrionale e sono state osservate diverse malformazioni come massa ventrale accentuata, asse corporeo ricurvo, malformazione della testa e occhi sottosviluppati o assenti. A livello epidermico, è stato osservato un aumento del volume delle cellule ciliate, delle cellule caliciformi e delle SSC. Nelle cellule secernenti è stato osservato un aumento del numero di vescicole di esocitosi e inoltre sono state rilevate modificazione della fucosilazione e della solfatazione nelle mucine secrete, alterando il ruolo protettivo e la funzione delle ciglia nelle cellule ciliate. Nelle cellule basali è aumentato il numero di mitosi e sono stati osservati anche processi mitotici nelle cellule caliciformi specializzate. A livello ultrastrutturale, è stato osservato un aumento degli spazi intercellulari e le cellule ciliate presentavano ciglia attaccate e swelling mitocondriale
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
Comparative histochemical analysis of intestinal glycoconjugates in the blunthead pufferfish Sphoeroides pachygaster and grey triggerfish Balistes capriscus (Teleostei: Tetraodontiformes)
No full textThe localization of intestinal glycoconjugates of the blunthead pufferfish Sphoeroides pachygaster and the grey triggerfish Balistes capriscus from the north-western Ionian Sea was analysed by histochemical methods (PAS, AB pH 2.5, HID) and lectin binding experiments (WGA, LFA, SBA, sialidase-SBA, PNA, sialidase-PNA, ConA, AAA, UEA-I, LTA) to assess how evolutionary loss of a functional stomach in S. pachygaster affects intestinal secretions relative to the B. capriscus, which retains the plesiomorphic gastric condition. Sphoeroides pachygaster had a lower content of acid mucins but more complex sialylation patterns than B. capriscus. GalNAc and GlcNAc residuals were present in both, but GalNAc residuals in S. pachygaster were subterminal to sialic acid. Balistes capriscus lacked galactosylated residuals and its enterocytes had a glycocalyx that differed in composition between the small intestine and the rectum and was missing from S. pachygaster. Functional and ecological implications of these findings are discussed
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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