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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Anterior segment morphology in angle closure

Siddiqi, Rizwana January 2015 (has links)
Primary Angle Closure Glaucoma (PACG) is a worldwide leading cause of irreversible blindness much more prevalent in Asia than in European-derived populations. Patterns of ethnic differences may account for prevalence variation of the disease. Recent papers have reported a predicted rise in European-derived populations. Ocular risks associated with PAC(G) include an axially small, hypermetropic eye with a large lens. Potentially, there are patients in the UK with 'at risk' ocular biometrics predisposing them to PAC(G). Biometric disparities between ethnicities infer morphological variation of PAC(G).The morphology of PAC(G) can be evaluated using ultrasound biomicroscopy (UBM) and the development of a novel linear probe has enhanced its clinical utility. UBM allows quantitative analysis of the anterior chamber, however, there are inherent difficulties in identifying the landmark scleral spur. Qualitative image analyses are urgently required to assess the morphology of closure. Clinical grading scales (CGS) have been successful in other areas within ophthalmology; their application to PAC(G) is investigated within this thesis. The specific aims of the thesis are to: a) examine biometric differences between Caucasian & Chinese patients with PAC(G); b) describe the development of a series of CGS for PAC(G) and c) validate the CGS.Biometric differences between Chinese and Caucasian sample populations exist. The Caucasian cohort exhibit typical biometric findings associated with PAC(G): significantly smaller eyes, shallower anterior chambers, larger lenses, and a significantly shorter vitreous depth, when compared to Chinese counterparts. Biometric differences lend support to variation of PAC(G) mechanisms between ethnicities. A series of clinical CGS were developed using a 'consensus' based approach. The results: utilize psychometric techniques to evaluate inter-observer error; analyse intra-observer agreement by visualising concordance; target pruning to eliminate inter-observer confusion when constructing the CGS. A new custom-made software was developed to evaluate the performance of the CGS. The results show good intra- and inter- observer repeatability to characterise the morphology of closure. This is the first study describing a comprehensive method to construct and validate CGS in PAC(G). These can be used to evaluate the morphology of closure and in the future assess the fidelity of PAC(G) management.
2

Posouzení validity klasifikace obtížností nové bouldrové oblasti / Validity of new boulder area difficulty scaling

Hannsmann, Johan January 2021 (has links)
Title: Validity assessment of the grading scale evaluation in a new bouldering area. Objectives: The aim of this work is to assess the grading scale validity of bouldering routes in a new area. Methods: Routes grading was verified by a group of six men and four women. The evaluation took place during one continuous visit in the rocks with an individual rest period between problems. The classification of each of the 10 ascents was conducted immediately after finishing the specific problem. It was done individually, without the possibility to consult their guesses and ideas. The proposed difficulties of the classified routes ranged from 12 to 17 IRCRA. Results: The average rating of the route difficulty classification was 0.89 IRCRA points higher than the initial suggestion, with minor differences between men and women. The influence of climbers' performance on their ability to assess routes' difficulty was statistically insignificant. Conclusion: The first climbers of boulders in the area of Goethe rock underestimate the climbing grades, which proves that the determination of difficulty in local climbing centers can be significantly skewed compared to established standards. Keywords: bouldering, grading scales, IRCRA, validity
3

The evaluation of bulbar redness grading scales

Schulze, Marc-Matthias January 2010 (has links)
The use of grading scales is common in clinical practice and research settings. A number of grading scales are available to the practitioner, however, despite their frequent use, they are only poorly understood and may be criticised for a number of things such as the variability of the assessments or the inequality of scale steps within or between scales. Hence, the global aim of this thesis was to study the McMonnies/Chapman-Davies (MC-D), Institute for Eye Research (IER), Efron, and validated bulbar redness (VBR) grading scales in order to (1) get a better understanding and (2) attempt a cross-calibration of the scales. After verifying the accuracy and precision of the objective and subjective techniques to be used (chapter 3), a series of experiments was conducted. The specific aims of this thesis were as follows: • Chapter 4: To use physical attributes of redness to determine the accuracy of the four bulbar redness grading scales. • Chapter 5: To use psychophysical scaling to estimate the perceived redness of the four bulbar redness grading scales. • Chapter 6: To investigate the effect of using reference anchors when scaling the grading scale images, and to convert grades between scales. • Chapter 7: To grade bulbar redness using cross-calibrated versions of the MC-D, IER, Efron, and VBR grading scales. Methods: • Chapter 4: Two image processing metrics, fractal dimension (D) and % pixel coverage (% PC), as well as photometric chromaticity (u’) were selected as physical measures to describe and compare redness in the four bulbar redness grading scales. Pearson correlation coefficients were calculated between each set of image metrics and the reference image grades to determine the accuracy of the scales. • Chapter 5: Ten naïve observers were asked to arrange printed copies of modified versions of the reference images (showing vascular detail only) across a distance of 1.5m for which only start and end point were indicated by 0 and 100, respectively (non-anchored scaling). After completion of scaling, the position of each image was hypothesised to reflect its perceived bulbar redness. The averaged perceived redness (across observers) for each image was used for comparison to the physical attributes of redness as determined in chapter 4. • Chapter 6: The experimental setup from chapter 5 was modified by providing the reference images of the VBR scale as additional, unlabelled anchors for psychophysical scaling (anchored scaling). Averaged perceived redness from anchored scaling was compared to non-anchored scaling, and perceived redness from anchored scaling was used to cross-calibrate grades between scales. • Chapter 7: The modified reference images of each grading scale were positioned within the 0 to 100 range according to their averaged perceived redness from anchored scaling, one scale at a time. The same 10 observers who had participated in the scaling experiments were asked to represent perceived bulbar redness of 16 sample images by placing them, one at a time, relative to the reference images of each scale. Perceived redness was taken as the measured position of the placed image from 0 and was averaged across observers. Results: • Chapter 4: Correlations were high between reference image grades and all sets of objective metrics (all Pearson’s r’s≥0.88, p≤0.05); each physical attribute pointed to a different scale as being most accurate. Independent of the physical attribute used, there were wide discrepancies between scale grades, with sometimes little overlap of equivalent levels when comparing the scales. • Chapter 5: The perceived redness of the reference images within each scale was ordered as expected, but not all consecutive within-scale levels were rated as having different redness. Perceived redness of the reference images varied between scales, with different ranges of severity being covered by the images. The perceived redness was strongly associated with the physical attributes of the reference images. • Chapter 6: There were differences in perceived redness range and when comparing reference levels between scales. Anchored scaling resulted in an apparent shift to lower perceived redness for all but one reference image compared to non-anchored scaling, with the rank order of the 20 images for both procedures remaining fairly constant (Spearman’s ρ=0.99). • Chapter 7: Overall, perceived redness depended on the sample image and the reference scale used (RM ANOVA; p=0.0008); 6 of the 16 images had a perceived redness that was significantly different between at least two of the scales. Between-scale correlation coefficients of concordance (CCC) ranged from 0.93 (IER vs. Efron) to 0.98 (VBR vs. Efron). Between-scale coefficients of repeatability (COR) ranged from 5 units (IER vs. VBR) to 8 units (IER vs. Efron) for the 0 to 100 range. Conclusions: • Chapter 4: Despite the generally strong linear associations between the physical characteristics of reference images in each scale, the scales themselves are not inherently accurate and are too different to allow for cross-calibration based on physical redness attributes. • Chapter 5: Subjective estimates of redness are based on a combination of chromaticity and vessel-based components. Psychophysical scaling of perceived redness lends itself to being used to cross calibrate the four clinical scales. • Chapter 6: The re-scaling of the reference images with anchored scaling suggests that redness was assessed based on within-scale characteristics and not using absolute redness scores, a mechanism that may be referred to as clinical scale constancy. The perceived redness data allow practitioners to modify the grades of the scale they commonly use so that comparisons of grading estimates between calibrated scales may be made. • Chapter 7: The use of the newly calibrated reference grades showed close agreement between grading estimates of all scales. The between-scale variability was similar to the variability typically observed when a single scale is repeatedly used. Perceived redness appears to be dependent upon the dynamic range of the reference images of the scale. In conclusion, this research showed that there are physical and perceptual differences between the reference images of all scales. A cross-calibration of the scales based on the perceived redness of the reference images provides practitioners with an opportunity to compare grades across scales, which is of particular value in research settings or if the same patient is seen by multiple practitioners who are familiar with using different scales.
4

The evaluation of bulbar redness grading scales

Schulze, Marc-Matthias January 2010 (has links)
The use of grading scales is common in clinical practice and research settings. A number of grading scales are available to the practitioner, however, despite their frequent use, they are only poorly understood and may be criticised for a number of things such as the variability of the assessments or the inequality of scale steps within or between scales. Hence, the global aim of this thesis was to study the McMonnies/Chapman-Davies (MC-D), Institute for Eye Research (IER), Efron, and validated bulbar redness (VBR) grading scales in order to (1) get a better understanding and (2) attempt a cross-calibration of the scales. After verifying the accuracy and precision of the objective and subjective techniques to be used (chapter 3), a series of experiments was conducted. The specific aims of this thesis were as follows: • Chapter 4: To use physical attributes of redness to determine the accuracy of the four bulbar redness grading scales. • Chapter 5: To use psychophysical scaling to estimate the perceived redness of the four bulbar redness grading scales. • Chapter 6: To investigate the effect of using reference anchors when scaling the grading scale images, and to convert grades between scales. • Chapter 7: To grade bulbar redness using cross-calibrated versions of the MC-D, IER, Efron, and VBR grading scales. Methods: • Chapter 4: Two image processing metrics, fractal dimension (D) and % pixel coverage (% PC), as well as photometric chromaticity (u’) were selected as physical measures to describe and compare redness in the four bulbar redness grading scales. Pearson correlation coefficients were calculated between each set of image metrics and the reference image grades to determine the accuracy of the scales. • Chapter 5: Ten naïve observers were asked to arrange printed copies of modified versions of the reference images (showing vascular detail only) across a distance of 1.5m for which only start and end point were indicated by 0 and 100, respectively (non-anchored scaling). After completion of scaling, the position of each image was hypothesised to reflect its perceived bulbar redness. The averaged perceived redness (across observers) for each image was used for comparison to the physical attributes of redness as determined in chapter 4. • Chapter 6: The experimental setup from chapter 5 was modified by providing the reference images of the VBR scale as additional, unlabelled anchors for psychophysical scaling (anchored scaling). Averaged perceived redness from anchored scaling was compared to non-anchored scaling, and perceived redness from anchored scaling was used to cross-calibrate grades between scales. • Chapter 7: The modified reference images of each grading scale were positioned within the 0 to 100 range according to their averaged perceived redness from anchored scaling, one scale at a time. The same 10 observers who had participated in the scaling experiments were asked to represent perceived bulbar redness of 16 sample images by placing them, one at a time, relative to the reference images of each scale. Perceived redness was taken as the measured position of the placed image from 0 and was averaged across observers. Results: • Chapter 4: Correlations were high between reference image grades and all sets of objective metrics (all Pearson’s r’s≥0.88, p≤0.05); each physical attribute pointed to a different scale as being most accurate. Independent of the physical attribute used, there were wide discrepancies between scale grades, with sometimes little overlap of equivalent levels when comparing the scales. • Chapter 5: The perceived redness of the reference images within each scale was ordered as expected, but not all consecutive within-scale levels were rated as having different redness. Perceived redness of the reference images varied between scales, with different ranges of severity being covered by the images. The perceived redness was strongly associated with the physical attributes of the reference images. • Chapter 6: There were differences in perceived redness range and when comparing reference levels between scales. Anchored scaling resulted in an apparent shift to lower perceived redness for all but one reference image compared to non-anchored scaling, with the rank order of the 20 images for both procedures remaining fairly constant (Spearman’s ρ=0.99). • Chapter 7: Overall, perceived redness depended on the sample image and the reference scale used (RM ANOVA; p=0.0008); 6 of the 16 images had a perceived redness that was significantly different between at least two of the scales. Between-scale correlation coefficients of concordance (CCC) ranged from 0.93 (IER vs. Efron) to 0.98 (VBR vs. Efron). Between-scale coefficients of repeatability (COR) ranged from 5 units (IER vs. VBR) to 8 units (IER vs. Efron) for the 0 to 100 range. Conclusions: • Chapter 4: Despite the generally strong linear associations between the physical characteristics of reference images in each scale, the scales themselves are not inherently accurate and are too different to allow for cross-calibration based on physical redness attributes. • Chapter 5: Subjective estimates of redness are based on a combination of chromaticity and vessel-based components. Psychophysical scaling of perceived redness lends itself to being used to cross calibrate the four clinical scales. • Chapter 6: The re-scaling of the reference images with anchored scaling suggests that redness was assessed based on within-scale characteristics and not using absolute redness scores, a mechanism that may be referred to as clinical scale constancy. The perceived redness data allow practitioners to modify the grades of the scale they commonly use so that comparisons of grading estimates between calibrated scales may be made. • Chapter 7: The use of the newly calibrated reference grades showed close agreement between grading estimates of all scales. The between-scale variability was similar to the variability typically observed when a single scale is repeatedly used. Perceived redness appears to be dependent upon the dynamic range of the reference images of the scale. In conclusion, this research showed that there are physical and perceptual differences between the reference images of all scales. A cross-calibration of the scales based on the perceived redness of the reference images provides practitioners with an opportunity to compare grades across scales, which is of particular value in research settings or if the same patient is seen by multiple practitioners who are familiar with using different scales.
5

Assessing oral skills : A study comparing the Swedish and Norwegian English syllabi with the Common European Framework of Reference

Olsson, Martin January 2016 (has links)
This is a comparative study of the Swedish and Norwegian syllabi for English for the minimum courses required in order to be allowed to apply for university courses in both countries. The study focuses on the assessment of oral production and what guidelines teachers and students are provided with in order to know what is to be assessed. As a reference point while comparing, the Common European Framework of Reference has been used as a framework for this study.  The comparison has been done solely in a text-oriented manner, comparing both of the syllabi with the reference document. In the conclusion, the results drawn from this comparison will be put against each other in order to see any differences between the two syllabi and the ways in which they have interpreted the reference document.  The conclusion was that both of the syllabi were largely inspired by the reference document and so turned out to be very similar in many aspects within oral proficiency assessment, as well as there were some aspects where they were quite different. The most obvious of these were the aspect of descriptors of different grade levels which was an aspect where all three documents differed in some manner, the Norwegian syllabus being the document that was least alike the two other documents.
6

No-Zero Policy in Middle School: A Comparison of High School Student Achievement

Dennis, Janelle 01 January 2018 (has links)
Local middle schools have begun implementing a no-zero policy, which compels teachers to assign grades no lower than 50% even if a student did not turn in assignments for grading. In the study setting, high school teachers are struggling to motivate students who have attended a middle school with a no-zero policy in place. High school students who have attended a middle school with a no-zero policy show signs of learned helplessness. The purpose of this study was to examine the differences in core course grades between high school students who attended a middle school with a no-zero policy (NZPMS) and high school students who attended a middle school without this policy that would compel the assignment of F grades if earned by the student (FPMS). The theoretical framework is Seligman's theory of learned helplessness. The sample included 1,396 students in a high school who attended either of the two middle schools. Comparisons between mean high school mathematics, science, and English grades were compared using a one-tailed t-test. Effect sizes were measured using Cohen's d. The findings indicated statistically significant small to medium differences in students' core course grades. Students who had attended the NZPMS earned lower high school core course grades in mathematics, science, and English than students who had attended FPMS. Professional development activities were created to train teachers and administrators at the NZPMS about the negative effects of awarding students with passing grades without expanding any or only minimal effort. Positive social change could occur for students' academic careers and professional lives if the no-zero policy is rescinded.

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