1,721,016 research outputs found
Design study of plasma targets for laser driven wakefield acceleration experiments
Full text linkIn this work, a characterisation conducted in the SPARC_LAB (LNF-INFN) laboratories on some plasma targets, i.e. different nozzle geometries and different types of capillaries, is presented. The main goal of the work is the study and the realisation of the plasma guiding process of a laser pulse, inside a plasma-filled capillary discharge. This technique is necessary to increase the acceleration length and thus the energy gain of the accelerated beam, in the external-injection scheme of the Laser Wake Field Acceleration (LWFA). Plasma density is a characteristic of fundamental importance as it determines both the guiding and the acceleration process. Two different methods of plasma density measurement, interferometric and spectroscopic, are therefore reported. Preliminary studies of new techniques for the diagnostics of plasma inside channels and new schemes for the delivery/extraction of laser pulses inside capillaries are proposed. All topics covered include theoretical study, one-dimensional and/or fluid-dynamic simulations, and experimental data
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
Imperatori sul Nilo: il viaggio di Settimio Severo in Egitto
No full textTra il 199 e il 200 d.C. l'imperatore Settimio Severo e la sua famiglia visitarono l'Egitto, fermandosi per qualche tempo ad Alessandria e risalendo poi il corso del Nilo fino ad arrivare a Syene (Assuan). Le fonti letterarie, epigrafiche e papirologiche riportano numerosi dettagli su questo viaggio, soffermandosi, in particolare, sulle riforme amministrative di Severo, sulla sua grande curiosità per la storia della civiltà egizia, e sulla sua indole superstiziosa e diffidente verso le pratiche divinatorie locali. Tutti questi aspetti combaciano bene con le notizie riportate da Cassio Dione e dall'Historia Augusta sulla personalità di Severo, che viene spesso descritto come un imperatore fortemente dedito al lavoro amministrativo e giudiziario, desideroso di migliorare la proprie conoscenze in campo storico e naturalistico, ma allo stesso tempo estremamente superstizioso. Notevoli sono inoltre le differenze con tra il viaggio di Severo e quello di Adriano del 130-131. Quest'ultimo si preoccupò soprattutto di diffondere usi e costumi ellenistici attraverso la fondazione di nuovi centri di cultura greca (Antinopolis) e il rafforzamento di quelli già esistenti (Alessandria), mostrando oltretutto un atteggiamento di tipo più intellettuale verso le antichità egiziane. Le visite di Adriano e Severo in Egitto mostrano, dunque, diverse attitudini verso il governo delle province, la cui origine può essere rintracciata nella diversa estrazione sociale di questi due imperatori e nelle differenze che contraddistinsero i loro cursus honorum
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