1,720,963 research outputs found
Metodi chimici e biochimici per misurare le concentrazioni e la tossicità di sostanze inquinanti in matrici ambientali
No full textIn questo lavoro di ricerca è stato misurato il grado di contaminazione originato da diverse classi di
composti organici in sedimenti e biota della Laguna di Venezia ed è stato utilizzato un biomarker per
stimare uno dei possibili effetti biologici generati da questi composti sugli organismi.
E' stato valutato l'andamento temporale e spaziale della contaminazione dei sedimenti superficiali da
PCB, IPA e Pesticidi Organoclorurati nel corso di quindici anni, dal 1987 al 1998, in 25 stazioni
uniformemente distribuite nella porzione centrale della Laguna di Venezia, I risultati mettono in
evidenza una diminuzione statisticamente significativa dal 1987 al 1998 per PCB e pesticidi
organoclorurati con percentuali di abbattimento in prossimità della zona industriale ài Porto Marghera
fino all'80 e 90 %. Al contrario, la contaminazione da IPA non è significativamente diminuita
nell'intervallo di tempo considerato, anzi in alcune zone in prossimità del centro storico veneziano
sembra essere in aumento per il continuo apporto di questi composti in Laguna. . .
Inoltre, è stata valutata la contamina none da Composti Organostannici, sia butilici che fenilici (TBT e
TPhT e i relativi metaboliti, DBT, MBT, DPhT e MPhT), rilasciati principalmente dalle vernici
antivegetative applicate sugli scafi delle barche. L'analisi in diversi comparti ambientali ha rilevato la
presenza di concentrazioni significativamente superiori nel biota piuttosto che nel sedimento e una
forte tendenza al bioaccumulo nei molluschi. La specie di mollusco gasteropode Hexaplex trunculus,
in particolare, è stata analizzata, oltre che per il contenuto di composti organostannici nei tessuti
(viscere e resto del corpo molle), anche per il grado di imposex. Questo fenomeno consiste
nell'imposizione di caratteristiche sessuali maschili (pene e vaso deferente) nelle femmine e. può
portare, allo stadio più acuto, alla sterilità e quindi impedire la riproduzione. Il grado di imposex nelle
popolazioni di H. trunculus analizzate in questo studio si è rivelato abbastanza elevato e nessuna delle
femmine ispezionate morfologicamente è risultata priva di modificazioni anatomiche. La lunghezza
del pene delle femmine è stata messa in relazione sia con il contenuto di TBT sia con la somma di
composti organostannici nell'intero organismo, ottenendo buone correlazioni nella forma di una curva
dose-risposta in entrambi i casi (rispettivamente r=0.917 e r=0.982 per n=l 1; p<0.05).
Al fine di verifìcare il possibile ruolo antagonista o sinergico giocato nello sviluppo dell'imposex da
altri composti in grado di perturbare il sistema endocrino, allo stesso modo del TBT, gli stessi
organismi di H. trunculus sono stati analizzati anche per il contenuto di PCB, Pesticidi
Organoclorurati e EPA. E' stato applicato il metodo PLS (Partial Least squares regression in latent
variables) per mettere in relazione la risposta biologica (imposex) con le concentrazioni delle quattro
classi di composti organici determinate nei tessuti del mollusco. Il modello chemiometrico mostra, con
una buona capacità predittiva della variabile dipendente, che le concentrazioni di PCB e Pesticidi
Organoclorurati contribuiscono positivamente a spiegare l' imposex, mentre gli IPA sono caratterizzati
da un effetto opposto ai Composti Organostannici, ai PCB e ai Pesticidi Organolorurati.
The level of pollution derived from different classes of organic compounds was estimated in sediments
and biota of the Lagoon of Venice and a biomarker was used to estimate one of the possible biological
effect of these compounds.
Temporal and spatial trends of the contamination by PCBs, PAHs and organochlorine compounds in
superficial sediments were evaluated at 25 stations uniformly distributed in the central portion of the
Lagoon in the period from 1987 to 1998. The results highlight a statistically significant difference
between 1987 and 1998 as regard PCBs and pesticides concentrations, with a reduction up to 80 and
90% at areas close to the industrial zone of Porto Marghera. On the contrary, PAH contamination has
not significantly decreased in the period considered and near the historical centre it seems rather to be
increased for the continuous input of these compounds to the Lagoon.
Moreover, the contamination by organotin compounds, both butyltins and phenyltins (TBT and TPhT
and the relative metabolites, DBT, MBT, DPhT and MPhT), mainly released from the antifouling
paints applied on the ship hulls, was measured. The analysis in different compartments of the
environment has pointed out significantly higher concentrations in the biota, rather than in the
sediments. Among the different species of biota analysed, molluscs are the ones that tend to
accumulate organotin compounds more than the others. The species of gastropod Hexaplex trimculus,
in addition to the content of organotin compounds in the tissues (visceral coil and rest of the soft
body), was analysed even for the degree of imposex. This phenomenon consists of the imposition of
male sexual characters (namely a penis and a vas deferens) on females and at its acute stage can lead
to sterility and prevent the reproduction. The level of imposex in the H. trunculus populations
analysed in this study was shown to be relatively high. No one of the morphologically inspected
females was free from abnormalities. Female penis length was related to the content of TBT and also
to the sum of butyltins and phenyltins in the entire organism, achieving a good correlation in the form
of a dose-response curve in both cases (r=0.917 and r=0.982 respectively, n=ll; p<0.05). In order to
verify the possible antagonistic or synergistic role of other endocrine disrupters in the development of
imposex, the same organisms of H. trunculus were also analysed for the content of PCBs, pesticides
and PAHs.
The PLS method (Partial Least squares regression in latent variables) was applied to relate the
imposex response (Y) to the concentrations of the four classes of compounds (X block) analysed in
this study. The chemometric model shows, with a good predictive capacity of the dependent variable,
that the concentrations of PCBs and pesticides positively contribute to the explanation of the imposex
effect. On the contrary, a negative effect seems to characterise PAHs in respect to PCBs, pesticides
and OTCs
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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