Biaxial cell stimulation : a mechanical validation

To analyse mechanotransduction resulting from tensile loading under defined conditions, various devices for in vitro cell stimulation have been developed. This work aimed to determine the strain distribution on the membrane of a commercially available device and its consistency with rising cycle numbers, as well as the amount of strain transferred to adherent cells. The strains and their behaviour within the stimulation device were determined using digital image correlation (DIC). The strain transferred to cells was measured on eGFP-transfected bone marrow-derived cells imaged with a fluorescence microscope. The analysis was performed by determining the coordinates of prominent positions on the cells, calculating vectors between the coordinates and their length changes with increasing applied tensile strain. The stimulation device was found to apply homogeneous (mean of standard deviations approx. 2% of mean strain) and reproducible strains in the central well area. However, on average, only half of the applied strain was transferred to the bone marrow-derived cells. Furthermore, the strain measured within the device increased significantly with an increasing number of cycles while the membrane's Young's modulus decreased, indicating permanent changes in the material during extended use. Thus, strain magnitudes do not match the system readout and results require careful interpretation, especially at high cycle numbers.

Spatial and temporal variations of mechanical properties and mineral content of the external callus during bone healing

After bone fracture, various cellular activities lead to the formation of different tissue types, which form the basis for the process of secondary bone healing. Although these tissues have been quantified by histology, their material properties are not well understood. Thus, the aim of this study is to correlate the spatial and temporal variations in the mineral content and the nanoindentation modulus of the callus formed via intramembranous ossification over the course of bone healing. Midshaft tibial samples from a sheep osteotomy model at time points of 2, 3, 6 and 9 weeks were employed. PMMA embedded blocks were used for quantitative back scattered electron imaging and nanoindentation of the newly formed periosteal callus near the cortex. The resulting indentation modulus maps show the heterogeneity in the modulus in the selected regions of the callus. The indentation modulus of the embedded callus is about 6 GPa at the early stage. At later stages of mineralization, the average indentation modulus reaches 14 GPa. There is a slight decrease in average indentation modulus in regions distant to the cortex, probably due to remodelling of the peripheral callus. The spatial and temporal distribution of mineral content in the callus tissue also illustrates the ongoing remodelling process observed from histological analysis. Most interestingly the average indentation modulus, even at 9 weeks, remains as low as 13 GPa, which is roughly 60% of that for cortical sheep bone. The decreased indentation modulus in the callus compared to cortex is due to the lower average mineral content and may be perhaps also due to the properties of the organic matrix which might be different from normal bone.

Development and validation of a pregnancy symptoms inventory

BACKGROUND. Physical symptoms are common in pregnancy and are predominantly associated with normal physiological changes. These symptoms have a social and economic cost, leading to absenteeism from work and additional medical interventions. There is currently no simple method for identifying common pregnancy related problems in the antenatal period. A validated tool, for use by pregnancy care providers would be useful. AIM: The aim of the project was to develop and validate a Pregnancy Symptoms Inventory for use by healthcare professionals (HCPs). METHODS: A list of symptoms was generated via expert consultation with midwives and obstetrician gynaecologists. Focus groups were conducted with pregnant women in their first, second or third trimester. The inventory was then tested for face validity and piloted for readability and comprehension. For test-re-test reliability, it was administered to the same women 2 to 3 days apart. Finally, outpatient midwives trialled the inventory for 1 month and rated its usefulness on a 10cm visual analogue scale (VAS). The number of referrals to other health care professionals was recorded during this month. RESULTS: Expert consultation and focus group discussions led to the generation of a 41-item inventory. Following face validity and readability testing, several items were modified. Individual item test re-test reliability was between .51 to 1 with the majority (34 items) scoring .0.70. During the testing phase, 211 surveys were collected in the 1 month trial. Tiredness (45.5%), poor sleep (27.5%) back pain (19.5%) and nausea (12.6%) were experienced often. Among the women surveyed, 16.2% claimed to sometimes or often be incontinent. Referrals to the incontinence nurse increased > 8 fold during the study period. The median rating by midwives of the ‘usefulness’ of the inventory was 8.4 (range 0.9 to 10). CONCLUSIONS: The Pregnancy Symptoms Inventory (PSI) was well accepted by women in the 1 month trial and may be a useful tool for pregnancy care providers and aids clinicians in early detection and subsequent treatment of symptoms. It shows promise for use in the research community for assessing the impact of lifestyle intervention in pregnancy.

Validation Gating for Non-Linear Non-Gaussian Target Tracking

This paper develops a general theory of validation gating for non-linear non-Gaussian mod- els. Validation gates are used in target tracking to cull very unlikely measurement-to-track associa- tions, before remaining association ambiguities are handled by a more comprehensive (and expensive) data association scheme. The essential property of a gate is to accept a high percentage of correct associ- ations, thus maximising track accuracy, but provide a su±ciently tight bound to minimise the number of ambiguous associations. For linear Gaussian systems, the ellipsoidal vali- dation gate is standard, and possesses the statistical property whereby a given threshold will accept a cer- tain percentage of true associations. This property does not hold for non-linear non-Gaussian models. As a system departs from linear-Gaussian, the ellip- soid gate tends to reject a higher than expected pro- portion of correct associations and permit an excess of false ones. In this paper, the concept of the ellip- soidal gate is extended to permit correct statistics for the non-linear non-Gaussian case. The new gate is demonstrated by a bearing-only tracking example.

Development and validation of a questionnaire designed to measure foot-health status

The aim of this study was to apply the principles of content, criterion, and construct validation to a new questionnaire specifically designed to measure foot-health status. One hundred eleven subjects completed two different questionnaires designed to measure foot health (the new Foot Health Status Questionnaire and the previously validated Foot Function Index) and underwent a clinical examination in order to provide data for a second-order confirmatory factor analysis. Presented herein is a psychometrically evaluated questionnaire that contains 13 items covering foot pain, foot function, footwear, and general foot health. The tool demonstrates a high degree of content, criterion, and construct validity and test-retest reliability.

Development of diagnostic and prognostic algorithms from vacuum circuit breaker restrike review and its validation proposal

The CIGRE WGs A3.20 and A3.24 identify the requirements of simulation tools to predict various stresses during the development and operational phases of medium voltage vacuum circuit breaker (VCB) testing. This paper reviews the modelling methodology [13], VCB models and tools to identify future research. It will include the application of the VCB model for the impending failure of a VCB using electro-magnetic-transient-program with diagnostic and prognostic algorithm development. The methodology developed for a VCB degradation model is to modify the dielectric equation to cover a restriking period of more than 1 millimetre.

Learning and teaching from the edge to centre stage : Critical factors in embedding sustainable university-wide engagement in external awards and grants funding initiatives.

Teaching awards, grants and fellowships are strategies used to recognise outstanding contributions to learning and teaching, encourage innovation, and to shift learning and teaching from the edge to centre stage. Examples range from school, faculty and institutional award and grant schemes to national schemes such as those offered by the Australian Learning and Teaching Council (ALTC), the Carnegie Foundation for the Advancement of Teaching in the United States, and the Fund for the Development of Teaching and Learning in higher education in the United Kingdom. The Queensland University of Technology (QUT) has experienced outstanding success in all areas of the ALTC funding since the inception of the Carrick Institute for Learning and Teaching in 2004. This paper reports on a study of the critical factors that have enabled sustainable and resilient institutional engagement with ALTC programs. As a lens for examining the QUT environment and practices, the study draws upon the five conditions of the framework for effective dissemination of innovation developed by Southwell, Gannaway, Orrell, Chalmers and Abraham (2005, 2010): 1. Effective, multi-level leadership and management 2. Climate of readiness for change 3. Availability of resources 4. Comprehensive systems in institutions and funding bodies 5. Funding design The discussion on the critical factors and practical and strategic lessons learnt for successful university-wide engagement offer insights for university leaders and staff who are responsible for learning and teaching award, grant and associated internal and external funding schemes.

Effect of external high pressures on the clay mineral sodium montmorillonite intercalated with methylated octadecylammonium bromide surfactants

Raman microprobe spectra of the clay mineral Wyoming SWy-2-sodium montmorillonite intercalated with the surfactants, methyltrioctadecylammonium bromide (TOMA) dimethyldiotadecylammonium bromide (DODMA) and octadecyl-trimethylammonium bromide (ODTMA), have been measured in the CH2 stretching region at external pressures up to ~40 kbar with the aid of a diamond-anvil cell. In the case of the intercalated clays containing TOMA and DODMA, the Raman data afford evidence for gauche to trans conformational changes in the orientation of the CH2 chains in the surfactants with increasing pressure. These conformational changes are reversed completely upon the release of pressure.

Investigating the development of the internal and external service tasks of non-executive directors: the case of the Netherlands (1997-2005)

During the last decade, globalisation and liberalisation of financial markets, changing societal expectations and corporate governance scandals have increased the attention for the fiduciary duties of non-executive directors. In this context, recent corporate governance reform initiatives have emphasised the control task and independence of non-executive directors. However, little attention has been paid to their impact on the external and internal service tasks of non-executive directors. Therefore, this paper investigates how the service tasks of non-executive directors have evolved in the Netherlands. Data on corporate governance at the top-100 listed companies in the Netherlands between 1997 and 2005 show that the emphasis on non-executive directors' external service task has shifted to their internal service task, i.e. from non-executive directors acting as boundary spanners to non-executive directors providing advice and counselling to executive directors. This shift in board responsibilities affects non-executive directors' ability to generate network benefits through board relationships and has implications for non-executive directors' functional requirements.