1,721,022 research outputs found
Monitoreo genético no invasivo de una población de nutrias silvestres en los Países Bajos.
No full textHeavy metals in dolphins from Northern Adriatic Sea and potential subtle toxic effects
No full textEnvironmental pollution represents one of the main threats for marine ecosystems conservation. Top predators are particularly exposed to contaminants; due to their anatomical and physiological characteristics, cetaceans can reach very high pollutants tissue body burdens (i.e. organochlorine and heavy metals). These marine mammals are thus considered as good indicators of marine environmental pollutants and among them heavy metals are one of the major contaminants classes.
Present research reports about the quantification of heavy metals in tissues of stranded bottlenose dolphins (Tursiops truncatus) from Northern Adriatic Sea and presents some speculation on possible subtle adverse effects exerted by these levels on the general health of the animals.
Stranded dolphins were collected along Northern Adriatic Sea coasts during a 5 years period and underwent necropsy for the determination of the causes of death. During examination, organs were sampled and stored at -20°C until analysis, which was performed with an Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) technique. Quantified metals were Cr, Ni, Cu, Zn, Hg, As, Se, Cd and Pb and data are reported as mg/kg (ppm) on a wet weight basis. When possible, gender and age of the animals were recorded.
All metals were at detectable levels, presenting a huge variation among animals and tissues. Interestingly, some of the most common contaminants for marine environment were detected at low levels, often below limit of quantification, also in accumulation target organs like liver and kidney. Mean heavy metals detected were to be considered as low, but high enough to exert a potential immunotoxic effect on animals, as the levels detected are comparable to those which proved to be active in vitro on lymphocytic cytotoxicity, apoptosis, lymphocytic proliferation and phagocytic activity, as confirmed by some anatomo-pathological observations of lymph node swelling. Some speculation on potential reproductive effect of detected heavy metals levels are also proposed, even if no clear evidence of altered reproductive activity was observed.
From obtained data there seems to be a reduced exposure to heavy metals, even thought a higher susceptibility to infectious diseases can be considered for studied animals
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
Parametri ecologici condizionanti la comunità ectoparassitaria in colonie italiane di Chirotteri
No full textLo studio delle comunità ectoparassitarie nei Chirotteri presenta numerosi spunti per approfondire le relazioni evolutive ospiteparassita,essendo le specie ospiti caratterizzate da un’ecologia complessa, con cambi di roost stagionali e scelte microclimatiche e di substrato differenziate, oltre che da una fenologia variabile, con una serie di ectoparassiti che si sono adattati a queste particolarità con scelte evolutive davvero inusuali. Perapprofondire questi temi stiamo campionando le faunule parassitarie in diverse specie di Chirotteri, correlandole con la specie ospite e la relativa struttura dei roost, sia in termini di composizione faunistica, sia di microclima e substrato. In questa analisi abbiamo preso in considerazione i risultati dei campionamenti effettuati su 5 specie di Chirotteri in 6 siti italiani. I campionamenti avvengono sia a vista, in modo occasionale, sia secondo un protocollo che prevede l’utilizzo di uno spray a base di piretroidi, innocui per i vertebrati e con buon potere abbattente sui parassiti. Questa procedura permette di raccogliere l’intera comunità di ectoparassiti da ogni singolo esemplare ospite. I parassiti di ogni individuo vengono successivamente posti in provette singole con alcool a 70° per poi essere identificati in laboratorio. I risultati preliminari qui esposti, su 789 esemplari appartenenti alle specie Myotis myotis,M. blythii, M. punicus, Miniopterus schreibersii e Rhinolophus hipposideros, rivelano come le colonie campionate siano caratterizzate da una faunula parassitaria nel complesso adeguatamente descritta in letteratura per quanto riguarda la biodiversità, ma ancora da elaborare in termini ecologici e di comunità. La biodiversità della faunula parassitaria è apparsa proporzionale alla numerosità degli ospiti all’interno del rifugio. Colonie con più specie di ospiti presentano un maggior numero di specie di ectoparassiti per ospite e un carico parassitario totale maggiore. Significativa è la differenza tra 2, 3
e 4 specie ospiti presenti nel rifugio, ma non molto significativa tra 4 e 5.
Le specie di Chirotteri che vivono in gruppi più numerosi e insistono su roost ipogei umidi e freddi, frequentati da diverse
generazioni, mostrano carichi parassitari ingenti in particolare di Nycteribidae (Diptera: Streblidae) e Spinturnicidae (Acarina:
Mesostigmata). Non è significativamente diverso il carico tra le tre specie di Myotis nelle diverse stazioni di campionamento. La presenza di Streblidae (Diptera: Hippoboscoidea) si accentra, oltre che in Sardegna, soprattutto in un sito della Toscana
centrale. L’unico rappresentante presente nella nostra fauna, Brachitarsinia flavipennis, predilige i Rhinolophidae e recentemente è stata ritrovata su Rhinolophus hipposideros; tuttavia nelle colonie riproduttive miste si porta a foraggiare anche su Miniopterus schreibersii oltre che sui Myotis spp. Gli Spinturnicidae sono molto abbondanti nella coppia Myotis myotis/M. blythii, in tutti gli ambienti, mentre i rappresentanti delle famiglie Argasidae e Ixodidae (Acarina: Ixodida) sono stati raccolti solo in determinate colonie o risultano numericamente consistenti solo in situazioni sanitarie di crisi, soprattutto nei
giovani pipistrelli. Si sollecita in questo ambito quindi un’ulteriore collaborazione da parte di quanti possano venire a contatto con parassiti per uno studio più ampio e che valuti ulteriori specie e più ambiti ecologici
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
Postmortem investigations on a leatherback turtle Dermochelys coriacea stranded along the Northern Adriatic coastline
No full textLeatherback sea turtles Dermochelys coriacea are regularly reported in the Mediterranean Sea but rarely reach the northern Adriatic Sea. In the summer of 2009, a well-preserved carcass of an adult female of this species was found dead along the coast of Lido di Venezia. A complete necropsy was carried out, along with evaluation of levels of tissue trace elements. The the post-mortem revealed acute severe bacterial gastroenteritis caused by Photobacterium damselae ssp. piscicida, an opportunistic agent that infected an apparently debilitated animal weakened by ingested plastic debris. High levels of heavy metals (Hg, Pb, Cd and As) found in the liver and kidneys might have contributed to the animal's demise. These findings support previous indications that marine debris is one of the major threats to marine animals, particularly for critically endangered species such as the leatherback turtle
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