1,721,053 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Changes in monochromatic aberrations during accommodation
No full textPurpose: The monochromatic aberrations of the human eye are known to vary considerably between individuals. However little is known about the similarity in monochromatic aberrations between the right and left eyes of an individual and how the aberrations in both eyes change as a function of accommodation level.\ud
Methods: The effect of accommodation on the nature and magnitude of monochromatic aberrations was studied using the aberroscope technique. The aberrations were measured in single dioptre steps of accommodation up to the subject's maximum amplitude of accommodation and were recorded in both eyes of eleven young subjects.\ud
Results: The longitudinal spherical aberration of the subjects because progressively more negative in power with increasing accommodation (p=0.0001). The aberration data showed a trend towards a higher mean-square-error of the wavefront (p=0.06) with increasing accommodation levels. The third-order components of the aberrations were found to be of greater magnitude than fourth-order components (about 4:1 for a 5mm pupil). There was substantial correlation in the magnitude and sign of the spherical aberration present in the fellow eyes of individuals, however other components of the wavefront showed little correlation between fellow eyes. There was little general correlation between fellow eyes in the third-order components (eg. Zernike C7 (lateral coma) or C8 (vertical coma) coefficients) of the wavefront.\ud
Conclusions: The significant trend toward higher negative spherical aberration with increasing accommodation levels was confirmed in this study and shown to continue at high levels of accommodation. The monochromatic aberrations of fellow eyes showed greatest similarity for spherical aberration, however little systematic correlation was evident between fellow eyes for third-order components of the wavefront.\ud
CR: Non
Longitudinal spherical aberration in contact lens correction of aphakia
No full textPurpose\ud
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Correction of aphakia in infants with standard spherical contact lenses results in significant levels of positive longitudinal spherical aberration (LSA). These infants often achieve relatively poor levels of visual acuity. We measured visual acuity for different object vergences in the presence of representative levels of LSA, and make recommendations for LSA management in contact lens corrections for aphakic infants. \ud
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Methods\ud
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Levels of LSA induced by rigid and soft lenses on eye were calculated using raytracing for typical aphakia corrections found at the ages 1 month, 1 year and 4 years. We then measured the likely effects of these LSA levels on visual performance. Twelve subjects between the ages of 21 and 28 were recruited and cycloplegia was induced prior to testing. LSA was induced by means of custom-designed aspheric rigid contact lenses positioned close to the eye. Visual acuity was measured with the Freiburg visual acuity test for object vergences from 2 to +2D. An artificial aperture of 4 mm was used to control the level of LSA. Eight LSA levels were tested between -3.67D and +8.14D. \ud
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Results\ud
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Peak visual acuity reduced at a rate of approximately 0.7 logMAR per dioptre LSA. For an average aphakia correction for a 1 month old (+35DS) and a 4mm pupil, the LSA induced by a rigid spherical lens on-eye is +4.86D. This would correspond to a drop in acuity of approximately 3 lines (0.33 logMAR). A soft spherical lens of the same power on-eye would induce +2.10D LSA which corresponds to approximately one and a half lines of acuity loss (0.14 logMAR), provided the lens flexed perfectly to the underlying cornea. Visual acuity improved for negative vergences (closer objects) in lenses with positive LSA and for positive vergences (further objects) in lenses with negative LSA, as expected. \ud
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Conclusions\ud
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The poor optics due to positive LSA in contact lens corrections for aphakia will potentially contribute to amblyopia. Correction of LSA in contact lenses can be achieved with an aspheric lens surface and correction strategies are presented for unilateral and bilateral aphakia in infants. CR: Non
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
Microfluctuations of steady-state accommodation and the cardiopulmonary system
No full textAbstractThe relationship between variations in steady-state accommodation (microfluctuations) and rhythmic cycles in cardiopulmonary system was investigated. As previously reported, vascular pulse frequency was consistently correlated with the high frequency component of steady-state accommodation microfluctuations. In a new finding, respiration rate and an associated cycle in the instantaneous pulse rate also showed a correlation with a low frequency component of the accommodation power spectra. This apparent coherence between respiration frequency and an accommodation low frequency component was maintained during rapid breathing and was evident at the expected frequency during regulated breathing patterns. This association may reflect the direct influence of the autonomic nervous system upon the ciliary muscle or may be caused by the modulation of intraocular pulse by the autonomic nervous system
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