1,721,050 research outputs found
Closed-form analytical design of optically transparent wideband absorbers for 5G technology
No full textThe design of new transparent absorbers for the upcoming fifth-generation (5G) technology is investigated. The absorbers consist of a matching layer, a lossy sheet, a spacer, and a back conducting layer (BCL). Both the matching layer and the spacer are one-quarter-wavelength thick and made of polyethylene terephthalate (PET). The lossy sheet and the BCL consist of indium tin oxide (ITO) thin films or graphene-PET laminates in order to avoid the use of any metal and to guarantee the optical transmittance. An innovative closed-form formulation is developed with the aim of evaluating the optimal values of sheet resistances of the lossy layers through analytical expressions. The absorption performances are investigated considering impinging plane waves with an incidence angle between 0° and 30°. The computed absorption coefficients in transverse magnetic (TM) or transverse electric (TE) modes are greater than 0.8, and the transmission coefficient is lower than 0.1 in the 5G frequency range from 25 up to 47 GHz, assuming that the matching layer and the spacer are 1.3 mm thick. The optical transmittance of the absorbers is evaluated in the wavelength range from 400 up to 700 nm by means of an accurate matrix simulation model, considering both optical polarizations, S (i.e., TE) and P (i.e., TM) for different incidence angles. The computed average optical transmittances of the designed absorbers are greater than 80% at 550 nm, i.e., at the wavelength corresponding to the maximum eye sensitivit
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
Implantation of a single chamber pace-maker in patients with triple mechanical valve prosthesis: utilizaztion of coronary sinus distal branches to stimulate the left ventricle.
No full text
Arresto cardiaco in pazienti ricoverati per scompenso cardiaco grave. Differenze cliniche a seconda della aritmia registrata al momento dell’evento terminale.
No full textAppropriate 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
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