1,720,982 research outputs found
Miopizzazione temporanea e sintomatologia soggettiva in operatori al videoterminale
No full textThe study covered a group of female VDT operators assigned to data entry and data acquisition. Subjective VDT-related symptoms of asthenopia were assessed by means of a questionnaire. All operators were examined by an ophthalmologist. Visual acuity was measured using vision tables with optotypes. In order to achieve an objective assessment of VDT-induced visual fatigue, refractive power was measured at the beginning and at the end of the shift, using an infra-red autorefractometer. Changes in refractive power were then related to VDT work and asthenopia symptoms. Visual acuity defects were observed in 63.5% of the operators; in 36% of the cases the subjects were either unaware of the defects or the defects were not adequately corrected. 62.5% of the operators complained of subjective asthenopia symptoms. Asthenopia was not related to the number of hours at the VDT. The results suggest that ametropic subjects are likely to be more susceptible to visual fatigue than emmetropic subjects, since there was a tendency for the prevalence of asthenopia to increase in the former group. A significant decrease in refractive power (temporary myopization) was observed in 20% of the operators at the end of the shift at the VDT: all these subjects also complained of asthenopia, compared to 50% of the workers without end-of-shift myopization. The difference between the groups was highly significant (p less than 0.01); contrarywise, none of the subjects without asthenopia developed myopization. On the basis of these results, it can be concluded that end-of-shift myopization, as measured by an automatic refractometer, may be used as a reliable objective measurement of VDT-related visual fatigu
The McCollough effect and visual fatigue induced by the use of green phosphorus monochromatic video terminals
No full textWe examined 101 students (40 men, 61 women) aged 16-19 years, working 1-3 hours daily with video display terminals (VDT) with luminous green characters on dark background. McCollough visual aftereffect (ME) was reported, almost occasionally, in 80.2% of the examined group. 68% of the students referred daily ME appearance. Usually the effect appeared after 1 hour or less of VDT work and might persist for 1 hour or more. ME prevalence and persistence were significantly greater in women than in men. Apparently no relations were observed between ME prevalence and VDT work hours of visual defects. ME prevalence and persistence were significantly related to VDT induced visual asthenopia symptoms, but not with ocular asthenopia. According to our results, ME appearance may represent an early index of individual susceptibility to visual asthenopia induced by green characters VDT and/or be itself a precocious visual asthenopia sympto
Serum type III procollagen peptide in asbestos workers: an early indicator of pulmonary fibrosis
No full texterum type III procollagen peptide (PIIIP) concentrations were determined in 36 male workers exposed to asbestos fibres in the production of asbestos cement items and in 13 healthy male controls. Mean (SD) PIIIP serum concentrations were 9.3 (1.5) ng/ml (range 7-12) in the controls and 13.7 (3.5)ng/ml (range 7.5-20) in the asbestos workers; the difference was statistically significant (p less than 0.01). The exposed workers were subdivided according to presence or absence of radiological signs of asbestosis and intensity and duration of exposure. PIIIP serum values of workers with asbestos related interstitial fibrosis were the highest of the groups at 14.6 (2.3) ng/ml. In workers with heavy exposure the PIIIP values were significantly related to duration of exposure (r = 0.95; p less than 0.01). PIIIP serum values may be a useful index for the early diagnosis of asbestos induced pulmonary fibrosis and its use should be considered as part of the biological monitoring of exposed worker
Visual fatigue in video display terminal operators: objective measure and relation to environmental conditions
No full textThe lighting conditions, luminance, contrast, and design of the workplace were studied in video display terminal (VDT) work stations operated by a group of female VDT data-acquisition clerks. VDT-induced symptoms were assessed by means of subject answers to a questionnaire. To measure VDT-induced ocular fatigue objectively, refraction power was determined before and at the end of workshift by an infrared autorefractometer. Job-induced refraction changes were then related to visual complaints and conditions in the workplace. The results confirmed that VDT data-acquisition work can lead to temporary myopia (myopization) in a remarkable percentage of operators; a significant correlation between eye discomfort, ocular asthenopia, and myopization was also found. Illumination levels, luminance, and contrast seem to be of paramount importance regarding visual symptoms: neither asthenopia nor myopization was observed when all of these conditions were adequate. If the ergonomic design of the workplace and the viewing distance are adequate, there are also usually fewer musculoskeletal symptoms. Our results suggest that changes in the ocular refraction status before and at the end of the workshift, as determined by an automatic refractometer, provide a good objective index of VDT-induced "ocular fatigue", which in our study proved to be significantly related to workplace conditions. © 1988 Springer-Verlag
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
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