1,720,987 research outputs found
Design of an L-S-Band Frequency Selective Rasorber for Dual-Band Absorption and In-Band Transmission
No full textIn this paper, a passive Frequency Selective Rasorber (FSR) for dual-band absorption and in-band transmission operating in the L and S bands is presented. The proposed FSR consists of two lossy Frequency Selective Surface (R-FSS) layers and a lossless FSS layer, with opportune substrates between them for a total thickness of 32 mm. The design procedure of each layer is investigated, and full-wave simulations are performed. The lossy FSSs comprise a modified square loop element loaded with lumped elements. On the other hand, the lossless FSS layer includes a band-pass filter made of a square patch inserted in a connected grid. The simulated results show that the proposed FSR achieves a transmission band from 2.4 to 2.9 GHz with a minimum insertion loss of 1.4 dB. The -10 dB dual-band absorption covers the range from 0.8-1 GHz and from 3.4-3.9 GHz. Furthermore, the presented structure exhibits stable performance against oblique incidences up to 40°
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
Impact of Clostridium difficile infection on pediatric inflammatory bowel disease.
No full textTo determine the prevalence of and explore possible differences in the risk for and symptoms of Clostridium difficile infection between patients with and without inflammatory bowel disease (IBD). STUDY DESIGN: Stool specimens from subjects with and without IBD were evaluated for the presence of C difficile toxins. Demographic information, diagnosis, anatomic location, disease activity, IBD therapy, hospitalizations, and antibiotic and proton pump inhibitor (PPI) exposures were recorded. RESULTS: A total of 193 specimens were collected from 81 patients with IBD and 112 patients without IBD. The prevalence of C difficile infection was significantly greater in the patients with IBD than in those without IBD (P = .004; chi2 = 0.003; odds ratio = 3.3; 95% confidence interval = 1.5 to 7.6). In the patients with IBD, the prevalence of active disease was significantly greater in the C difficile-infected patients than in the uninfected patients (P < .0001). Colonic involvement was found in all patients with IBD. The specific type of IBD, IBD therapy, and antibiotic and PPI exposures that predisposed patients with IBD to C difficile infection were not identified, whereas hospitalization was significantly more frequent in the patients without IBD (P = .025). CONCLUSIONS: Our findings indicate that in children, IBD is associated with an increased prevalence of C difficile infection. The specific risk factors reported in adults were not identified in these children, suggesting the possible involvement of other mechanisms for acquiring the pathogen
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
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