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Spettroscopia di risonanza magnetica nucleare (NMR) "in vitro" di cristallini umani catarattosi
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Sensitivity and specificity of a visual acuity screening protocol performed with the Lea Symbols 15-line folding distance chart in preschool children.
No full textPurpose: The aim of this study was to assess the feasibility of a visual acuity
(VA) test using the Lea Symbols 15-line folding distance chart and its diagnostic
validity in detecting VA deficiency in preschool children.
Methods: A group of 149 children aged 38–54 months underwent VA examination
performed with the Lea 15-line folding optotype at a distance of 3 metres,
according to a test protocol described in the Methods section. After the VA test,
a complete ophthalmological examination, including cycloplegic retinoscopy,
a cover test and examination of the anterior and posterior segments, was performed
on each child in order to detect any VA-threatening ocular abnormality.
The Lea Symbols test’s sensitivity, specificity, positive and negative likelihood
ratios (LR +, LR )) and the receiver operating characteristic (ROC) curve
were calculated by means of standard procedures using each VA level of the
chart from 0.1 to 1 (1–0 logMAR) as a cut-off point.
Results: The Lea Symbols test could be successfully used in 95.9% of the population.
The most useful cut-off points for screening preschool children were
found to be 0.8 (LR +5.73, LR ) 0.05) or 0.63 (LR +11.7, LR ) 0.23).
Conclusion: The Lea Symbols test proved to be clinically useful in detecting
VA deficiency in preschool children. The choice between the two best performing
cut-off levels should be made according to the expected cost-effectiveness
of the screening programme
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
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