1,720,959 research outputs found
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
Design and operation of a femtosecond micro-CARS experimental apparatus
Full text linkLa spettroscopia Raman consente di misurare mappe vibrazionali di campioni con alta risoluzione spaziale, utili per l’identificazione di composti chimici senza l’utilizzo di marcatori. In generale però, le tecniche di Raman spontaneo soffrono di alcuni svantaggi, principalmente dovuti ai bassi livelli di segnale e alla eventuale presenza di segnali di fluorescenza, che possono limitarne l’applicabilità. Per contro, le tecniche di Raman coerente, come ad esempio la diffusione Raman Anti-Stokes coerente (CARS), sfruttando la nonlinearità dell’interazione tra luce di sonda e campione, permettono di superare i limiti sopra descritti, e per questa ragione sono ampiamente utilizzate nonostante la maggior complessità e il costo dell’apparato sperimentale. D’altronde, negli ultimi venti anni, la grande diffusione di oscillatori laser a impulsi ultracorti e la disponibilità di fibre a cristalli fotonici per la generazione di luce bianca coerente hanno facilitato lo sviluppo di microscopi CARS a bassa energia di eccitazione e tempi di acquisizione brevi, che sono di particolare utilità in campo biologico e biomedico. In questo rapporto tecnico, dopo un breve richiamo alle caratteristiche della spettroscopia CARS al femtosecondo, viene descritto il microspettrometro CARS realizzato nel C. R. Casaccia nell’ambito di un progetto ENEA inter-dipartimentale. Inoltre, vengono riportati e discussi i risultati sperimentali ottenuti durante i primi due anni di operatività del sistema.Raman spectroscopy allows the measurement of vibrational maps of samples with high spatial resolution, useful for the identification of chemical compounds without the use of labels. In general, however, spontaneous Raman techniques suffer from some disadvantages, mainly due to low signal levels and the possible presence of fluorescence signals, which can limit their applicability. On the other hand, coherent Raman techniques, such as Coherent Anti-Stokes Raman Scattering (CARS), exploiting the nonlinearity of the interaction between probe and sample light, permit to overcome the limits described above, and for this reason they are widely used despite the greater complexity and cost of the experimental apparatus. On the other hand, in the last twenty years, the great diffusion of ultrashort pulse laser oscillators and the availability of photonic crystal fibers for the generation of coherent white light have facilitated the development of CARS microscopes with low excitation energy and short acquisition times, which are particularly useful in the biological and biomedical fields. In this technical report, after a brief reference to the characteristics of the femtosecond CARS spectroscopy, the CARS microspectrometer made in C. R. Casaccia in the framework of an inter-departmental ENEA project is described. Furthermore, the experimental results obtained during the first two years of operation of the system are reported and 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
Characterization of supercontinuum generation in a photonic crystal fiber for uses in multiplex CARS microspectroscopy
No full textCoherent anti-Stokes Raman scattering (CARS) is a versatile technique for vibrational imaging that can be realized by a simple setup using a single femtosecond laser oscillator. For such a layout, supercontinuum generation in a photonic crystal fiber (PCF) is commonly used to produce a broadband Stokes beam in the so-called multiplex CARS spectroscopy; accordingly, characterization of the supercontinuum beam is a necessary requirement to perform controlled experiments. In this paper, we first perform simulations and characterizations of the supercontinuum spectra produced by a PCF in conditions encountered in a typical single-oscillator multiplex CARS setup. Good agreement between the experimental and simulated supercontinuum spectra is obtained in the whole emission band and for different PCF working conditions, by accurate choice of the simulation input parameters and by accounting for the input beam chirp in the numerical code. The influence of PCF working conditions on the CARS signal measured on a reference sample is also shown. To this regard, we also study the long-term stability of the Stokes beam and of the associated CARS signal, using the Allan variance to determine a limit to the acquisition time in CARS measurements. We show that Stokes and CARS long-term spectral fluctuations are on a timescale of some minutes in our setup, setting an indicative limit to the practical acquisition time for reliable CARS measurements. Based on this work, good control over the measurement of vibrational bands by CARS microscopy can be achieved in view of optimized performances in specific spectral bands
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
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