1,721,013 research outputs found
Strategie di vita di Thunnus thynnus nel bacino Mediterraneo: evidenze da indagini geochimiche e biologiche
No full textThunnus thynnus è uno delle più importanti specie commerciali di tonno presenti all’interno del bacino Mediterraneo e nell’oceano Atlantico .
Negli ultimi anni, un forte incremento nello sforzo di pesca esercitato su questa specie ha comportato una drastica riduzione nel numero di organismi di T. thynnus a scala globale (Sissenwine et al., 1998; SCRS, 2002). L’attuale gestione delle politiche di pesca per questa specie si basa sulla conoscenza del fatto che le due principali zone di spawning di T. thynnus sono localizzate nel mar Mediterraneo e nel Golfo del Messico. Inoltre, una serie di evidenze scientifiche basate su dati di rilevamento satellitare di un numero discreto di organismi congiuntamente a studi relativi alla chimica degli otoliti prelevati da un numero ridotto di esemplari della medesima specie, suggeriscono eventi di migrazioni trans-oceaniche di T. thynnus che sembrano mettere fortemente in dubbio il concetto di “confine di gestione” degli stocks di questa risorsa recentemente proposto dall’ICCAT (International Commission for the Conservation of Atlantic Tunas) (Magnuson et al., 1994; Lutcavage et al., 1999; Block et al., 2001,2005; Rooker et al., 2006).
Il recente sviluppo di tecnologie adeguate allo studio della chimica di campioni di ridottissime dimensioni ha permesso di utilizzare dati di chimica del carbonato biogenico degli otoliti presenti all’interno di pesci come “record” puntuale delle masse d’acqua all’interno delle quali gli organismi sono vissuti (Thresher, 1999) e quindi come affidabili strumenti di “stock discrimination” (Secor and Rooker 2000; Campana and Thorrold 2001). Il carbonato aragonitico degli otoliti, precipitando continuamente durante la crescita dell’individuo, incorpora in proporzione sostanzialmente lineare all’acqua di mare, elementi chimici vicarianti del calcio fornendo una marcatura naturale delle masse d’acqua all’interno delle quali gli organismi sono vissuti. Un ampio spettro di esperimenti eseguiti in ambiente controllato (Kalish, 1989; Arai et al., 1995, 1996, Fowler et al., 1995; Limburg 1996; Townsend et al., 1995; Radtke et al., 1990, Sadovy et al., 1992) e in ambiente naturale (Secor et al., 1995; Gallahar & Kingsford 1996; Tzeng 1996; Mugiya et al.,1995) hanno chiaramente dimostrato l’esistenza di tale proporzionalità nella concentrazione di alcuni elementi vicarianti del calcio (in particolare Mg, Sr, Ba, Cd) all’interno dell’aragonite dei pesci e nell’acqua di mare. I lavori di Campana (1999) e Bath, et al., (2000) suggeriscono che soprattutto il Ba nel carbonato degli otoliti, sembra riflettere la chimica delle masse d’acqua all’interno delle quali vivono gli organismi con limitati effetti legati alla termodinamica (T, S, etc.) di incorporazione nel carbonato stesso.
In questo lavoro di ricerca vengono presentati i risultati di un’ampia indagine analitica in LA-ICP-MS effettuata su un elevato numero di otoliti di esemplari di T. thynnus pescati nel bacino Mediterraneo e nel Golfo del Messico. I risultati si riferiscono alla misura dei valori di concentrazione di un numero discreto di elementi in tracce (Sr, Mg e Ba) su incrementi annuali di otoliti.
Un approfondito studio statistico dei risultati ottenuti ha permesso di individuare chiaramente i periodi di vita dei diversi organismi studiati trascorsi in area atlantica e in area mediterranea e pertanto di ipotizzare strategie di vita diverse per questa specie di tonno.
I dati sono stati confermati da ulteriori analisi eseguite su esemplari di T.thynnus in stadio giovanile e larvale, utilizzati quindi come marker biologici mediterranei.
Inoltre in questo lavoro di tesi sono state presentate delle informazioni preliminari relative alla distribuzione di una suite di elementi in traccia (Sc, T, V, Cr, Mn, Co, Ni, Cu, Zn, Rb, Y, Zr, Nb, Mo,Cd, Cs e Pb).
Tale dataset rappresentando il primo del genere, possa essere di aiuto nel guidare studi più approfonditi per i diversi elementi investigati, soprattutto in termini di concentrazioni medie presenti per i diversi analiti nel carbonato degli otoliti di T.thynnus
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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