Haptically simulating soft tissue using spherical voxel and reactive agents

This thesis describes technology developed by the author enabling trainee surgeons to perform needle insertion procedures with force feedback (haptics) on a virtual patient. Addition of the sense of touch to medical simulation is arguably the most important step forward in the evolution of haptic technology to this day.

Association of high-sensitivity C-reactive protein with de novo major depression

Background: Although there is cross-sectional evidence that changes in the immune system contribute to the pathophysiology of depression, longitudinal data capable of elucidating cause and effect relationships are lacking.

Aims: We aimed to determine whether subclinical systemic inflammation, as measured by serum high-sensitivity C-reactive protein (hsCRP) concentration, is associated with an increased risk of de novo major depressive disorder.

Method: Major depressive disorder was diagnosed using a clinical interview (SCID-I/NP). This is a retrospective cohort study; from a population-based sample of 1494 randomly selected women recruited at baseline during the period 1994-7, 822 were followed for a decade and provided measures of both exposure and outcome. Of these women, 644 (aged 20-84 years) had no prior history of depression at baseline and were eligible for analysis.

Results: During 5827 person-years of follow-up, 48 cases of de novo major depressive disorder were identified. The hazard ratio (HR) for depression increased by 44% for each standard deviation increase in log-transformed hsCRP (ln-hsCRP) (HR = 1.44, 95% CI 1.04-1.99), after adjusting for weight, smoking and use of non-steroidal anti-inflammatory drugs. Further adjustment for other lifestyle factors, medications and comorbidity failed to explain the observed increased risk for depression.

Conclusions: Serum hsCRP is an independent risk marker for de novo major depressive disorder in women. This supports an aetiological role for inflammatory activity in the pathophysiology of depression.

Reactive block copolymer modified thermosets : highly ordered nanostructures and improved properties

A highly ordered poly(dimethyl siloxane)-poly(glycidyl methacrylate) (PDMS-PGMA) reactive diblock copolymer was synthesized and used to modify bisphenol A-type epoxy resin (ER). The PDMS-PGMA block copolymer consisted of epoxy-miscible PGMA blocks and an epoxy-immiscible PDMS block. The PGMA reactive block of the block copolymer formed covalent bonds with cured epoxy and was involved in the network formation, and the PDMS block phase separated to give different ordered and disordered nanostructures at different blend compositions. The solvent cast PDMS-PGMA diblock copolymer showed ordered hexagonal cylindrical morphology. A highly ordered morphology consisting of hexagonal cylinders inside the lamellar morphology was observed in the cured PDMS-PGMA block copolymer. In the cured ER/PDMS-PGMA blends, a variety of morphologies including lamellar, cubic and worm-like and spherical nanostructures were detected depending on the blend composition. Moreover, the addition of this reactive diblock copolymer significantly increases the hydrophobicity and the glass transition temperature. It also improves the tensile strength and tensile ductility of the nanostructured thermosets at low diblock copolymer contents.

Reclaiming spent liquor from cotton reactive dyebaths using nanofiltration membrane for possible reuse of water and salt

During dyeing, salts are placed in a dyebath to aid the fixation of various dyes on to the fabric while bases are added to raise the pH from around neutral to pH 11. Afterwards, the used dyebath solution, called dyebath spent liquor, is discharged with almost all the salts and bases added as well as unfixed dyes. Consequently, a lot of raw materials are lost in the waste stream ending up in the environment as pollutants. In this study, possibilities of reusing water and salts of dyebathes were investigated, using a nanofiltration membrane. When the salt concentration in the spent liquor was increased from 10 to 80 g/L, the salt rejection by membrane was found to decrease initially; however, the salt rejection increased over the time, which was not expected. The aggregation of dye was also studied and found to decrease in the concentrate when the salt concentration was increased. This may be due to the aggregation of salt in the concentrate, which explains the increase in salt rejection. This information is useful for the textile industry in evaluating the treated water quality for the purpose of reuse.

Measuring the impact of arthritis on worker productivity : perspectives, methodologic issues and contextual factors

Leading up to the Outcome Measures in Rheumatology (OMERACT) 10 meeting, the goal of the Worker Productivity Special Interest Group (WP-SIG) was to make progress on 3 key issues that relate to the application and interpretation of worker productivity outcomes in arthritis: (1) to review existing conceptual frameworks to help consolidate our intended target and scope of measurement; (2) to examine the methodologic issues associated with our goal of combining multiple indicators of worker productivity loss (e.g., absenteeism <—> presenteeism) into a single comprehensive outcome; and (3) to examine the relevant contextual factors of work and potential implications for the interpretation of scores derived from existing outcome measures. Progress was made on all 3 issues at OMERACT 10. We identified 3 theoretical frameworks that offered unique but converging perspectives on worker productivity loss and/or work disability to provide guidance with classification, selection, and future recommendation of outcomes. Several measurement and analytic approaches to combine absenteeism and presenteeism outcomes were proposed, and the need for further validation of such approaches was also recognized. Finally, participants at the WP-SIG were engaged to brainstorm and provide preliminary endorsements to support key contextual factors of worker productivity through an anonymous “dot voting” exercise. A total of 24 specific factors were identified, with 16 receiving ≥ 1 vote among members, reflecting highly diverse views on specific factors that were considered most important. Moving forward, further progress on these issues remains a priority to help inform the best application of worker productivity outcomes in arthritis research.

Plagiarism : proactive prevention instead of reactive punishment

Purpose - This study investigated whether providing university students with extra feedback regarding their referencing improves their referencing confidence and reduces their propensity to plagiarise. The study also sought to increase our understanding of what factors underlie student plagiarism.

Design/methodology/approach - Undergraduate and post-graduate accounting students were surveyed regarding their experience when completing a formative essay designed to give feedback on their referencing ability. All students in one undergraduate and one postgraduate accounting course were invited to participate in a post-assessment, electronically administered survey consisting of sixteen question.

Findings - The results indicate that a considerable number of the students perceived the formative assessment to be of benefit with respect to improving their referencing confidence. A significant proportion of the students indicated that their understanding of what constitutes plagiarism and their confidence in avoiding plagiarism improved as a result of the assessment and its associated feedback.

Research limitations/implications - This study supports the provision of assessment designed to assist students with improving their ability to both recognise and avoid plagiarism in their written work. However, this research has not investigated whether these types of exercises lead to an actual reduction in the incidence of plagiarism in tertiary student cohorts. This is an area for future research.

The effect of cocoa supplementation on hepatic steatosis, reactive oxygen species and LFABP in a rat model of NASH

Background: Non alcoholic steatohepatitis is hypothesised to develop via a mechanism involving fat accumulation and oxidative stress. The current study aimed to investigate if an increase in oxidative stress was associated with changes in the expression of liver fatty acid binding protein in a rat model of non alcoholic steatohepatitis and whether cocoa supplementation attenuated those changes.

Methods: Female Sprague Dawley rats were fed a high fat control diet, a high fat methionine choline deficient diet, or one of four 12.5% cocoa supplementation regimes in combination with the high fat methionine choline deficient diet.

Results: Liver fatty acid binding protein mRNA and protein levels were reduced in the liver of animals with fatty liver disease when compared to controls. Increased hepatic fat content was accompanied by higher levels of oxidative stress in animals with fatty liver disease when compared to controls. An inverse association was found between the levels of hepatic liver fatty acid binding protein and the level of hepatic oxidative stress in fatty liver disease. Elevated NADPH oxidase protein levels were detected in the liver of animals with increased severity in inflammation and fibrosis. Cocoa supplementation was associated with partial attenuation of these pathological changes, although the severity of liver disease induced by the methionine choline deficient diet prevented complete reversal of any disease associated changes. Red blood cell glutathione was increased by cocoa supplementation, whereas liver glutathione was reduced by cocoa compared to methionine choline deficient diet fed animals.

Conclusion: These findings suggest a potential role for liver fatty acid binding protein and NADPH oxidase in the development of non alcoholic steatohepatitis. Furthermore, cocoa supplementation may have be of therapeutic benefit in less sever forms of NASH.

Reliability and validity of a reactive agility test for Australian football

Purpose: The aim of this study was to test the reliability and construct validity of a reactive agility test (RAT), designed for Australian Football (AF).

Methods: Study I tested the reliability of the RAT, with 20 elite junior AF players (17.44 ± 0.55 y) completing the test on two occasions separated by 1 wk. Study II tested its construct validity by comparing the performance of 60 participants (16.60 ± 0.50 y) spread over three aged-matched population groups: 20 athletes participating in a State Under-18 AF league who had represented their state at national competitions (elite), 20 athletes participating in the same league who had not represented their state (subelite), and 20 healthy males who did not play AF (controls).

Results: Test-retest reliability reported a strong correlation (0.91), with no significant difference (P = .22) between the mean results (1.74 ± 0.07 s and 1.76 ± 0.07 s) obtained (split 2+3). Nonparametric tests (Kruskal-Wallis and Mann-Whitney) revealed both AF groups performed significantly faster on all measures than the control group (ranging from P = .001 to .005), with significant differences also reported between the two AF groups (ranging from P = .001 to .046). Stepwise discriminant analyses found total time discriminated between the groups, correctly classifying 75% of the participants.

Conclusions: The RAT used within this study demonstrates evidence of reliability and construct validity. It further suggests the ability of a reactive component within agility test designs to discriminate among athletes of different competition levels, highlighting its importance within training activities.