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Upward lightning (UL) has become a major threat to the growing number of wind turbines producing renewable electricity. It can be much more destructive than downward lightning due to the large charge transfer involved in the discharge process. Ground-truth lightning current measurements indicate that less than 50% of UL could be detected by lightning location systems (LLS). UL is expected to be the dominant lightning type during the cold season. However, current standards for assessing the risk of lightning at wind turbines mainly consider summer lightning, which is derived from LLS. This study assesses the risk of LLS-detectable and LLS-undetectable UL at wind turbines using direct UL measurements at instrumented towers. These are linked to meteorological data using random forests. The meteorological drivers for the absence/occurrence of UL are found from these models. In a second step, the results of the tower-trained models are extended to a larger study area (central and northern Germany). The tower-trained models for LLS-detectable lightning are independently verified at wind turbine sites in this area and found to reliably diagnose this type of UL. Risk maps based on cold season case study events show that high probabilities in the study area coincide with actual UL flashes. This lends credibility to the application of the model to all UL types, increasing both risk and affected areas., Competing Interests: The authors declare no conflicts of interest relevant to this study., (© 2023. The Authors.)

Upward lightning is rarer than downward lightning and requires tall (100+ m) structures to initiate. It may be either self-initiated or triggered by other lightning discharges. While conventional lightning location systems (LLSs) detect most of the upward lightning flashes superimposed by pulses or return strokes, they miss a specific flash type that consists only of a continuous current. Globally, only few specially instrumented towers can record this flash type. The proliferation of wind turbines in combination with damages from upward lightning necessitates an improved understanding under which conditions self-initiated upward lightning and the continuous-current-only subtype occur. This study uses a random forest machine learning model to find the larger-scale meteorological conditions favoring the occurrence of the different phenomena. It combines ground truth lightning current measurements at the specially instrumented tower at Gaisberg mountain in Austria with variables from larger-scale meteorological reanalysis data (ERA5). These variables reliably explain whether upward lightning is self-initiated or triggered by other lightning discharges. The most important variable is the height of the -10°C isotherm above the tall structure: the closer it is, the higher is the probability of self-initiated upward lightning. For the different flash types, this study finds a relationship to the larger-scale electrification conditions and the LLS-detected lightning situation in the vicinity. Lower amounts of supercooled liquid water, solid, and liquid differently sized particles and no LLS-detected lightning events nearby favor the continuous-current-only subtype compared to the other subtypes, which preferentially occur with LLS-detected lightning events within 3 km from the Gaisberg Tower., Competing Interests: The authors declare no conflicts of interest relevant to this study., (© 2023. The Authors.)

In this paper, a full-wave two-dimensional Finite-Difference-Time-Domain model is developed to evaluate the propagation effects of lightning electromagnetic fields over mountainous terrain in the Earth-ionosphere waveguide. In the model, we investigate the effect of the Earth-ionosphere waveguide structure and medium parameters, including the effect of the ionospheric cold plasma characteristics, the effect of the Earth curvature, and the propagation effects over mountainous terrain. For the first time, the obtained results are validated against simultaneous experimental data consisting of lightning currents measured at the Säntis Tower and electric fields measured in Neudorf, Austria, located at 380-km distance from the tower. It is shown that both the time delays and amplitudes of the lightning electromagnetic fields at 380-km distance can be strongly affected by the ionospheric electron density profile, the mountainous terrain, and the Earth curvature. After taking into account the effect of the irregular terrain between the Säntis Tower and the field measurement station, the vertical electric fields calculated by using our model are found to be in good agreement with the corresponding measured cases occurred in both daytime and nighttime. The ideal approximation used in either the classical solutions or the simplified models might lead to inaccuracies in the estimated reflection height. Furthermore, we discuss the sensitivity of our results by considering different return stroke models, as well as different typical values of the return stroke speed and of the ground conductivity., (©2019. The Authors.)

Purpose: To add a new set of 24 sentence optotypes to the German version of the RADNER reading charts and to investigate whether sentences constructed based upon an optimised concept of sentence optotypes can be used together with the original 38 sentences., Methods: Twenty-eight optimised sentence optotypes were constructed based upon the concept of sentence optotypes as established for the RADNER Reading Charts, with words having the same number of characters and syllables being placed in the same positions. The best comparable sentences were statistically selected in 30 volunteers. Reading speed and the number of errors were determined. Validity was analysed in comparison to a 111-word long standardised paragraph and 7 of the 38 original sentence optotypes., Results: The mean reading speed obtained with the 28 sentences was 192.30±26.69 words per minute (wpm), as compared with 192.47±25.32 wpm for the 7 original sentence optotypes and 165.28±20.82 wpm for the long paragraph; 24 of the 28 optimised sentences met our selection criteria for reading speed/time (mean reading speed: 192.41±26.58). The mean number of reading errors was 0.10±0.30. The correlation between the 24 optimised sentence optotypes and the long paragraph was r=0.90. Reliability analyses yielded an overall Cronbach's α coefficient of 0.992., Conclusion: The 24 new sentence optotypes can be integrated into the existing set of 38 original sentences. Since all the statistical results obtained were similar to those of the original sentences, the best possible reliability had apparently already been achieved with the original sentence optotypes., Competing Interests: Competing interests: WR receives royalties for the RADNER reading charts, of which seven optotypes were used. All other named authors have no affiliation with or involvement in any organisation or entity with any financial interest in the subject matter or materials discussed in this manuscript., (Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.)

Purpose: To compare the reading time and reading speed measurements obtained with a stopwatch with those of an automated computer program for measuring reading speed and acuity (rad-rd © ; patent: AT 504635B1/10-2006)., Methods: The rad-rd © was used (in conjunction with a PC and microphone) for the computer-based measurements. In rotation, each of four examiners took a turn reading the 12 sentences from one of the four RADNER Reading Charts to three other examiners, who served as stoppers. The stoppers simultaneously measured the reading time with a stopwatch while a fifth investigator used the rad-rd © to obtain computerized measurements. The stopwatch measurements were then statistically compared with the rad-rd © measurements., Results: The mean reading time obtained with the stopwatch measurements was 4.34 ± 0.57 seconds (196.21 ± 21.79 wpm), versus 4.44 ± 0.59 seconds (192.24 ± 22.20 wpm) by computer measurement (r = 0.84). Of the 144 stopwatch measurements, 97 (67.36%) were shorter, and 47 (32.64%) were equal to (n = 5) or longer than the computer measurements. The mean difference for the shorter measurements was -0.17 ± 0.1 seconds (3.91% of the mean reading time), and the mean difference for the longer measurements was 0.11 ± 0.1 seconds (2.53% of the mean reading time). Most differences ranged from -0.1 to 0.1 seconds (42.36%). The results did not differ significantly among the four stoppers., Conclusion: The rad-rd © is an accurate, automated computer program for measuring reading time. Stopwatch measurements, although subject to inaccuracy from several sources, remain a reliable and simple method for analysis of reading performance., (© 2016 Acta Ophthalmologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.)

Purpose: To develop 27 short sentence optotypes for the Portuguese version of the Radner Reading Charts., Methods: Thirty-four Portuguese sentences were constructed following the concept of the Radner Reading Charts to obtain highly comparable sentences in terms of lexical difficulty, syntactical complexity, word length, number of syllables, and position of words. A long text (106 words) at the 5th grade reading level was also tested to assess the validity of the reading speeds obtained with the short sentences. The short sentences and long text were tested in 50 volunteers with similar educational backgrounds (mean age 30.98 years ± 6.99 years, range 19-47 years). Reading speeds were measured with a stop-watch and reported as words per minute (wpm). The reading time for each of the short sentences to be selected for the chart was defined as falling within the range of the mean ± 0.40 × standard deviation (SD)., Results: The overall mean reading speed for each of the short sentences was 235.43 ± 36.39 wpm. The 27 sentences with a mean between 220.8 and 250.0 wpm (overall mean ± 0.40 × SD) were selected for construction of the reading charts. The mean reading speed for the long text was 212.42 ± 26.20 wpm. Correlation between the selected short sentences and long text was high (r =0.86). Reliability analysis yielded an overall Cronbach's alpha coefficient of 0.97., Conclusions: The 27 short Portuguese sentences were highly comparable in terms of syntactical structure, number, position and length of words, lexical difficulty, and reading length. This reading test can overcome the limitations of the current tests for homogeneity and comparability, reducing subjectivity in the evaluation of the functional outcomes of medical and surgical ophthalmologic treatments.

Purpose: To investigate the reliability, validity, and statistical comparability of long paragraphs that were developed to be equivalent in construction and difficulty., Methods: Seven long paragraphs were developed that were equal in syntax, morphology, and number and position of words (111), with the same number of syllables (179) and number of characters (660). For validity analyses, the paragraphs were compared with the mean reading speed of a set of seven sentence optotypes of the RADNER Reading Charts (mean of 7 × 14 = 98 words read). Reliability analyses were performed by calculating the Cronbach's alpha value and the corrected total item correlation. Sixty participants (aged 20-77 years) read the paragraphs and the sentences (distance 40 cm; font: Times New Roman 12 pt). Test items were presented randomly; reading length was measured with a stopwatch., Results: Reliability analysis yielded a Cronbach's alpha value of 0.988. When the long paragraphs were compared in pairwise fashion, significant differences were found in 13 of the 21 pairs (p < 0.05). In two sequences of three paragraphs each and in eight pairs of paragraphs, the paragraphs did not differ significantly, and these paragraph combinations are therefore suitable for comparative research studies. The mean reading speed was 173.34 ± 24.01 words per minute (wpm) for the long paragraphs and 198.26 ± 28.60 wpm for the sentence optotypes. The maximum difference in reading speed was 5.55 % for the long paragraphs and 2.95 % for the short sentence optotypes. The correlation between long paragraphs and sentence optotypes was high (r = 0.9243)., Conclusions: Despite good reliability and equivalence in construction and degree of difficulty, a statistically significant difference in reading speed can occur between long paragraphs. Since statistical significance should be dependent only on the persons tested, either standardizing long paragraphs for statistical equality of reading speed measurements or increasing the number of presented paragraphs is recommended for comparative investigations.

Purpose: To develop 28 short sentence optotypes for the English version of the Radner Reading Charts that are as comparable as possible in number and length of words, as well as in difficulty and syntactical construction., Methods: Thirty-four English sentences were constructed following the method used for other Radner Reading Charts to obtain "sentence optotypes" with comparable structure and the same lexical and grammatical difficulty. Best comparable sentences were statistically selected and standardized in 50 volunteers. Reading speed and the number of errors were determined. Validity was analyzed with a 124-word long 4th-grade paragraph of the Florida Comprehensive Assessment Test®. Computerized measurements of reading parameters were performed with the RADNER Reading Device (RAD-RD©; in conjunction with a PC and microphone)., Results: The mean reading speed obtained with the 28 selected short sentences was 201.53 ± 35.88 words per minute (wpm), as compared to 215.01 ± 30.37 wpm for the long paragraph. The mean reading times were 4.30 ± 0.79 s and 35.26 ± 4.85 s, respectively. The mean number of reading errors was 0.11 ± 0.34. The correlation between the short sentences and the long paragraph was high (r = 0.76; p < 0.05; n = 50). Reliability analyses yielded an overall Cronbach's alpha coefficient of 0.9743., Conclusion: The present study indicates that the 28 selected English sentence optotypes are comparable in terms of both lexical difficulty as well as in reading length, and it demonstrates the validity and reliability of such sentences as test items for determining reading parameters such as reading acuity and speed.

Purpose: To evaluate reading performance of patients with monofocal intraocular lenses (IOLs) (Acrysof SN60WF) with or without reading glasses under bright and dim light conditions., Setting: Austrian Academy of Ophthalmology, Vienna, Austria., Design: Evaluation of a diagnostic test or technology., Methods: In pseudophakic patients, the spherical refractive error was limited to between +0.50 diopter (D) and -0.75 D with astigmatism of 0.75 D (mean spherical equivalent: right eye, -0.08 ± 0.43 [SD]; left eye, -0.15 ± 0.35). Near addition was +2.75 D. Reading performance was assessed binocularly with or without reading glasses at an illumination of 100 candelas (cd)/m(2) and 4 cd/m(2) using the Radner Reading Charts., Results: In the 25 patients evaluated, binocularly, the mean corrected distance visual acuity was -0.07 ± 0.06 logMAR and the mean uncorrected distance visual acuity was 0.01 ± 0.11 logMAR. The mean reading acuity with reading glasses was 0.02 ± 0.10 logRAD at 100 cd/m(2) and 0.12 ± 0.14 logRAD at 4 cd/m(2). Without reading glasses, it was 0.44 ± 0.13 logRAD and 0.56 ± 0.16 logRAD, respectively (P < .05). Without reading glasses and at 100 cd/m(2), 40% of patients read 0.4 logRAD at more than 80 words per minute (wpm), 68% exceeded this limit at 0.5 logRAD, and 92% exceeded it at 0.6 logRAD. The mean reading speed at 0.5 logRAD was 134.76 ± 48.22 wpm; with reading glasses it was 167.65 ± 32.77 wpm (P < .05)., Conclusion: A considerable percentage of patients with monofocal IOLs read newspaper print size without glasses under good light conditions., (Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.)

The case of a 23-year-old mountaineer who was hit by a lightning strike to the occiput causing a large central visual field defect and bilateral tympanic membrane ruptures is described. Owing to extreme agitation, the patient was sent into a drug-induced coma for 3 days. After extubation, she experienced simple and complex visual hallucinations for several days, but otherwise largely recovered. Neuropsychological tests revealed deficits in fast visual detection tasks and non-verbal learning and indicated a right temporal lobe dysfunction, consistent with a right temporal focus on electroencephalography. At 4 months after the accident, she developed a psychological reaction consisting of nightmares, with reappearance of the complex visual hallucinations and a depressive syndrome. Using the European Cooperation for Lightning Detection network, a meteorological system for lightning surveillance, the exact geographical location and nature of the lightning strike were retrospectively retraced.

The case of a 23-year-old mountaineer who was hit by a lightning strike to the occiput causing a large central visual field defect and bilateral tympanic membrane ruptures is described. Owing to extreme agitation, the patient was set to a drug-induced coma for 3 days. After extubation, she experienced simple and complex visual hallucinations for several days, but otherwise recovered largely. Neuropsychological tests revealed deficits in fast visual detection tasks and non-verbal learning, and indicated a right temporal lobe dysfunction, consistent with a right temporal focus on electroencephalography. Four months after the accident, she developed a psychological reaction consisting of nightmares with reappearance of the complex visual hallucinations and a depressive syndrome. Using the European Cooperation for Lightning Detection network, a meteorological system for lightning surveillance, the exact geographical location and nature of the lightning flash were retrospectively retraced.

Purpose: To compare the effect of erbium:YAG laser photocapsulotomy (ELC), continuous curvilinear capsulorhexis (CCC), and high-frequency capsulotomy (HFC) on anterior capsule edges using light microscopy (LM) and transmission electron microscopy (TEM)., Setting: Department of Ophthalmology, Department of Histology and Embryology II, University of Vienna, Vienna, Austria., Methods: Five anterior capsule membranes were obtained experimentally by ELC, which was performed with the Oertli MicroLaser photoemulsification tip in eyes from 5 human cadavers. Thirty anterior capsule membranes were obtained during cataract surgery by CCC (n = 15) or, in cases with poor or missing red fundus reflexes, by HFC (n = 15). Continuous curvilinear capsulorhexis was performed conventionally with a manual, bent, 27-gauge cannula, and HFC was performed according to Klöti. Membranes were processed and examined by LM and TEM according to standard procedures., Results: The edges obtained by ELC showed mild signs of denaturation and mechanical disruption, tears, and micro-tears. Lens capsule edges obtained by CCC were smooth with no irregularities in any specimen; the edges were beveled anteriorly to posteriorly with no evidence of tearing. Edges produced by HFC were considerably wider; the surfaces showed distinct denaturation, preformed tears, and micro-tears. The edges were surrounded by a nonhomogeneous mass, which consisted mainly of denatured lens capsule material., Conclusions: Of the 3 techniques, CCC produced the mildest tissue damage. The histological damage at ELC edges was relatively mild and intermediate compared with that seen at CCC and HFC edges. These observations suggest that ELC is an appropriate option for anterior capsulotomy in cataract surgery.