1,720,959 research outputs found
L'azoto totale nelle torbide e relazioni con i parametri idrologici: primi dati
No full textIl trasporto torbido dei corsi d’acqua può essere considerato un indicatore dei fenomeni d’erosione del suolo che si manifestano sui versanti, nell’ambito del bacino. Il trasporto torbido è costituito da solidi in sospensione di granulometria variabile, dalle argille alle sabbie, in funzione dei parametri idraulici, litopedologici, vegetazionali del bacino. Numerose sono le indagini sui processi di trasporto che concordano nell’attribuire ai solidi sospesi il ruolo di veicolo per la migrazione degli agenti inquinanti e dei nutrienti . La concentrazione di tali sostanze, nei solidi in sospensione, può arrivare a diversi ordini di grandezza maggiori rispetto alla loro concentrazione nella frazione liquida, in fase disciolta. In particolare è stato provato il ruolo di vettore preferenziale degli aggregati di particelle fini come argilla e limo . Inoltre numerosi studi hanno provato come il tasso di azoto sia tendenzialmente in crescita negli acquiferi e nelle acque superficiali e come il ciclo naturale dell’azoto sia ormai modificato, a causa dei fertilizzanti e degli scarichi zootecnici e fognari . La necessità di dati sperimentali rende il monitoraggio fluviale un basilare tassello nell’ambito della gestione e della protezione dell’ambiente e, nel caso specifico, per il controllo dell’erosione del suolo, dell’inquinamento e dell’eutrofizzazione delle acque di superficie. Nel presente lavoro si riportano i primi risultati conseguiti, nell’ambito di un più ampio progetto, relativamente alle relazioni, in campioni di torbida fluviale, tra la concentrazione dell’azoto totale rilevato nei solidi sospesi, la concentrazione e la granulometria dei solidi sospesi. Si propone inoltre un primo tentativo di stima dell’azoto perso a livello di bacino, attraverso il vettore dei solidi sospesi fluviali.Lo studio si avvale di una rete di monitoraggio fluviale avviata nell’aprile del 1997 dal DEIAgra della Facoltà di Agraria col supporto dell’Autorità di Bacino del Reno, che vede operative le seguenti stazioni di rilevamento idrologico-torbidimetrico in continuo:T. Sillaro, con un bacino di 137,6 km2, avviata nell'aprile 1997, T. Lavino (82,6 km2), operativa dal settembre 1998,T. Savena (168,9 km2 ) dall’ottobre 2000
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
Chromatin structure of the Saccharomyces cerevisiae DNA topoisomerase I promoter in different growth phases
No full textWe have determined the chromatin organization of the Saccharomyces cerevisiae DNA topoisomerase I promoter. Three nucleo somal core particles have been mapped at nucleotide level over the promoter region, encompassing the presumptive TATA sequence and the two RNA initiation sites; the most upstream nucleosome particle forms on to a 29 bp-long poly(dA-dT) element. This simple organization remains constant throughout both the logarithmic and the linear phase of growth, with the exception of an increased accessibility to micrococcal nuclease of the nucleosome covering the TATA box and the RNA initiation sites during the diauxic shift (the switching from the fermentative to the respiratory metabolism) in parallel with an increase of the DNA topoisomerase I mRNA. In addition, a strong disorganization of the bulk chromatin structure in the late stationary phase is also reported
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
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