Cerebellar augmented joint control for a humanoid robot

The joints of a humanoid robot experience disturbances of markedly different magnitudes during the course of a walking gait. Consequently, simple feedback control techniques poorly track desired joint trajectories. This paper explores the addition of a control system inspired by the architecture of the cerebellum to improve system response. This system learns to compensate the changes in load that occur during a cycle of motion. The joint compensation scheme, called Trajectory Error Learning, augments the existing feedback control loop on a humanoid robot. The results from tests on the GuRoo platform show an improvement in system response for the system when augmented with the cerebellar compensator.

Is it necessary to re-fuse a non-union of a hallux metatarsophalangeal joint arthrodesis?

BACKGROUND: The standard treatment for a non-union of the hallux metatarsophalangeal joint fusion has been to revise the fusion. Revision fusion is technically more demanding, often involving bone grafting, more substantial fixation and prolonged period of immobilization postoperatively. We present data to suggest that removal of hardware and debridement alone is an alternative treatment option. ---------- MATERIALS AND METHODS: A case note review identified patients with a symptomatic non-union after hallux metatarsophalangeal joint (MTPJ) fusion. It is our practice to offer these patients revision fusion or removal of hardware and debridement. For the seven patients that chose hardware removal and were left with a pseudarthrosis, a matched control group was selected from patients who had had successful fusions. Three outcome scores were used. Hallux valgus and dorsiflexion angles were recorded.---------- RESULTS: One hundred thirty-nine hallux MTPJ arthrodeses were carried out. Fourteen non-unions were identified. The rate of non-union in males and following previous hallux MTPJ surgery was 19% and 24%, respectively. In females undergoing a primary MTPJ fusion, the rate was 2.4%. Twelve non-union patients were reviewed at 27 months (mean). Eleven patients had elected to undergo removal of hardware and debridement. Four patients with pseudarthrosis were unhappy with the results and proceeded to either revision fusion or MTPJ replacement. Seven non-union patients, who had removal of hardware alone, had outcome scores marginally worse compared to those with successful fusions.---------- CONCLUSION: Removal of hardware alone is a reasonable option to offer as a relatively minor procedure following a failed arthrodesis of the first MTPJ. This must be accepted on the proviso that in this study four out of 11 (36%) patients proceeded to a revision first MTPJ fusion or first MTPJ replacement. We also found that the rate of non-union in primary first MTPJ fusion was significantly higher in males and those patients who had undergone previous surgery.

Employer evasion of workers’ entitlements 1968 – 1995: why, what and whose?

Employer non-compliance with workers’ entitlements has been largely ignored in Australian industrial relations. The legal and regulatory literature however, identifies arguments relating to employer propensity to evade regulatory requirements, as well as highlighting environmental factors that may influence such behaviour. This article explores these issues in the Australian federal industrial relations jurisdiction, as well as providing a picture of employer evasion of minimum labour standards between 1986 and 1995: who is exploited and in respect of what entitlements. Industry contexts and common characteristics of non-compliance are outlined by exploration of 30 awards ranked by the extent of underpayments recovered by the federal inspectorate during the period. Employer evasion of workers’ entitlements is arguably a calculated business decision, prompted or facilitated by intense competition, precarious employment (particularly female and youth), non-unionized workplaces and under-resourced enforcement agencies.

Shakedown stress analysis of insulated rail joint (IRJ)

A finite element numerical simulation is carried out to examine stress distributions on railhead in the cicinity of the endpost of an insulated rail joint. The contact patch and pressure distribution are considered using modified Hertzian simulation. A combined elasto-plastic material modelling available in Abaqus is employed in the simulation. A dynamic load factor of 1.21 is considered in modelling for the wheel load based on a previous study as part of this on going research. Shakedown theorem is employed in this study. A peak pressure load which is above the shakedown limit is determined as input load. As a result, a progressive damage in the railhead has been captured as depicted in the equivalent plastic strain plot.

Perioperative mortality after hemiarthroplasty related to fixation method : a study based on the Australian Orthopaedic Association National Joint Replacement Registry

Background and purpose: The appropriate fixation method for hemiarthroplasty of the hip as it relates to implant survivorship and patient mortality is a matter of ongoing debate. We examined the influence of fixation method on revision rate and mortality.----- ----- Methods: We analyzed approximately 25,000 hemiarthroplasty cases from the AOA National Joint Replacement Registry. Deaths at 1 day, 1 week, 1 month, and 1 year were compared for all patients and among subgroups based on implant type.----- ----- Results: Patients treated with cemented monoblock hemiarthroplasty had a 1.7-times higher day-1 mortality compared to uncemented monoblock components (p < 0.001). This finding was reversed by 1 week, 1 month, and 1 year after surgery (p < 0.001). Modular hemiarthroplasties did not reveal a difference in mortality between fixation methods at any time point.----- ----- Interpretation: This study shows lower (or similar) overall mortality with cemented hemiarthroplasty of the hip.

Elasto-plastic stress analysis of an insulated rail joint (IRJ) with a loading below shakedown limit

A finite element numerical simulation is carried out to examine stress distributions on railhead in the vicinity of the endpost of a insulated rail joint. The contact patch and pressure distribution are considered using modified Hertzian formulation. A combined elasto-plastic material modelling available in Abaqus is employed in the simulation. A dynamic load factor of 1.21 is considered in modelling for the wheel load based on a previous study as part of this on going research. Shakedown theorem is employed in this study. A peak pressure load which is above the shakedown limit is determined as input load. As a result, a progressive damage in the railhead has been captured as depicted in the equivalent plastic strain plot.

Employer-based support for registered nurses undertaking postgraduate study via distance education

Previous literature has focused on the need for support of undergraduate nursing students during clinical placements. Little is known about the support provided by employers for registered nurses (RNs) who pursue further education. This study sought to identify and describe the types, levels and perceived need for support in the workplace for RNs as they undertake further postgraduate nursing study by distance education (DE).Using an exploratory descriptive design a self-report questionnaire was distributed to a convenient sample of 270 RNs working in one acute care public hospital in Tasmania, Australia.92 questionnaires (response rate 34%) were returned with 26 (28%) reporting being currently enrolled in further study by DE and a further 50 (54)% of RNs planning future study. Results revealed that 100% of participants with a Masters degree completed this by DE. There were differences between the support sought by RNs to that offered by employers, and 16 (34%) who had done or were currently doing DE study, received no support to undertake DE. There was an overwhelming desire by RNs for support; 87 (94%), with a majority believing some support should be mandatory 76 (83%).This study may encourage employers to introduce structured support systems that will actively assist nurses to pursue further study. © 2010.

Experimental and finite element analysis of a double strap joint between steel plates and normal modulus CFRP

Strengthening of steel structures using externally-bonded carbon fibre reinforced polymers ‘CFRP’ is a rapidly developing technique. This paper describes the behaviour of axially loaded flat steel plates strengthened using carbon fibre reinforced polymer sheets. Two steel plates were joined together with adhesive and followed by the application of carbon fibre sheet double strap joint with different bond lengths. The behaviour of the specimens was further investigated by using nonlinear finite element analysis to predict the failure modes and load capacity. In this study, bond failure is the dominant failure mode for normal modulus (240 GPa) CFRP bonding which closely matched the results of finite elements. The predicted ultimate loads from the FE analysis are found to be in good agreement with experimental values.