1,720,977 research outputs found
Ecological and sanitary risk associated with organochlorine compound bioaccumulation in populations of Anguilla Anguilla from Mediterranean coastal waters.
No full textEcotoxicity of pp’DDE to Daphnia magna
No full textpp'-Dichlorodiphenyl-dichloroethylene (pp'DDE), a metabolite of pp'-dichlorodiphenyl-trichloroethane poses a risk for many ecosystems in spite of the banning of the parent compound because of its persistence and bioaccumulability. Nevertheless, the knowledge of acute and chronic toxicity on aquatic organisms is still very poor. In the present study, Daphnia magna was exposed to varying concentrations of pp'DDE in water and through diet to determine both acute toxicity and potential for effects on reproduction and survivability. The 48 h IC50 was 5.08 μg L-1 (3.76-7.01 μg L-1). As pp'DDE concentration in water was not stable and the amount assumed by food cannot be established with certainty, the results of chronic toxicity tests were expressed as the concentration in the organism which caused a negative effect. Grazing activity was affected with a pp'DDE concentration in the organism of 24 ng mg-1 d.w., while the lowest observed effect concentration for fecundity reduction was 109 ng mg-1 d.w
Use of Anguilla anguilla for biomonitoring persistent organic pollutants (POP) in brackish and riverine waters in Central and Southern Italy
No full textEcologia delle acque interne
No full textDell'oltre miliardo e 300 milioni di chilometri cubi di acqua esistente sul nostro pianeta, solo 35 milioni è acqua dolce (poco più del 2,5% del totale) e di questi, la maggior parte è sotto forma di ghiaccio (nelle calotte polari e nei grandi ghiacciai di montagna). Questi pochi dati in sintesi, fanno subito capire come l'acqua sia veramente un bene prezioso da tutelare, soprattutto oggi. "Ecologia delle acque interne", dopo una breve introduzione sulle proprietà e il ciclo dell'acqua, ha come obiettivo l'analisi degli ambienti acquatici per arrivare a individuare gli strumenti di gestione degli ecosistemi e delle risorse idriche. Oltre alle acque correnti e ai laghi, considerati separatamente per scopi di studio ma unitariamente e su scala di bacino per le problematiche di sorveglianza e gestione, sono state prese in considerazione anche le acque sotterranee. Un punto di forza del testo riguarda la trattazione volutamente semplice che fa ricorso ad esemplificazioni per lo più riferite a corpi idrici italiani. Non mancano, tuttavia, i riferimenti ad altre aree del pianeta, soprattutto nei casi in cui lo sfruttamento delle risorse idriche abbia portato ad alterazioni irreversibili degli ecosistemi e dove le risorse idriche rappresentano il fattore limitante per lo sviluppo delle società umane
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
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