Gait and electromyographic analysis of patients recovering after limb-saving surgery

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Factors controlling phytoplankton ice-edge blooms in the marginal ice-zone of the northwestern Weddell Sea during sea ice retreat 1988:field observations and mathematical modelling

The factors controlling phytoplankton bloom development in the marginal ice zone of the northwestern Weddell Sea were investigated during the EPOS (Leg 2) expedition (1988). Measurements were made of physical and chemical processes and biological activities associated with the process of ice-melting and their controlling variables particularly light limitation mediated by vertical stability and ice-cover, trace metal deficiency and grazing pressure. The combined observations and process studies show that the initiation of the phytoplankton bloom, dominated by nanoplanktonic species, was determined by the physical processes operating in the marginal ice zone at the time of ice melting. The additional effects of grazing pressure by protozoa and deep mixing appeared responsible for a rather moderate phytoplankton biomass (4 mg Chl a m−3) with a relatively narrow geographical extent (100–150 km). The rôle of trace constituents, in particular iron, was minor. The importance of each factor during the seasonal development of the ice-edge phytoplankton bloom was studied through modelling of reasonable scenarios of meteorological and biological forcing, making use of a one-dimensional coupled physical-biological model. The analysis of simulations clearly shows that wind mixing events – their duration, strength and frequency – determines both the distance from the ice-edge of the sea ice associated phytoplankton bloom and the occurrence in the ice-free area of secondary phytoplankton blooms during the summer period. The magnitude and extent of the ice-edge bloom is determined by the combined action of meteorological conditions and grazing pressure. In the absence of grazers, a maximum ice-edge bloom of 7.5 mg Chl a m−3 is predicted under averaged wind conditions of 8 m s−1. Extreme constant wind scenarios (4-14 m s−1) combined with realistic grazing pressure predict maximum ice-edge phytoplankton concentrations varying from 11.5 to 2 mg Chl a m−3. Persistent violent wind conditions (≥ 14 m s−1) are shown to prevent blooms from developing even during the brightest period of the year

Optimal Design of Composite Structures by Advanced Mixed Integer Nonlinear Optimization

The objective of this case series study was reautomatization of gait after limb-saving surgery for tumors at a laboratory of gait analysis. Twelve patients (9 males and 3 females; mean age, 38 years) who underwent limb-saving surgery of the lower limb at least 1 year previously and ten normal subjects (3 males and 7 females; mean age, 37.5 years) were studied. The main outcome measures were walking speed and stride time duration under normal walking conditions as well as the use of different types of constraints. Patients walked with a lower preferred walking speed than the normal subjects. Patients showed a higher coefficient of variation of stride time in normal walking as well as complex walking compared with normal subjects. During walking with constraints, a significant decrease in stride time was found in patients but not in normal subjects. Although restoration of gait after limb-saving surgery is impressive, it is not complete (lower walking speed) and can break down under conditions of visual and cognitive load. Hence, the application of complex tasks reveals that gait reautomatization is not complete in these patients during a period of 2 to 5 years after surgery

Health scares: professional priorities

Currently, many health scholars are concerned about health scares. But what do they mean by the term ‘health scare’ – are health scares an identifiable phenomenon, and how do we currently understand their causation and consequences? By collecting and analyzing published articles about events considered to be health scares, this paper maps the current views of scholars on their characteristics and causes. Results show that health scares are generally understood as events characterized by fears of catastrophic consequences but little actual mortality. However, the social and economic impacts of these events have often been severe. This survey shows that health scares can be usefully sorted into 6 categories, each with identifiable internal dynamics, suggesting different communications strategies to achieve resolution in each category. Using the social amplification of risk framework, the conditions under which risk signals were amplified were traced in general terms among major stakeholders. Simple causes for health scare events could not be identified, though some triggers did emerge. Importantly, public ignorance of real risk, media scaremongering, and political inaction could be dismissed as primary explanations, though they were sometimes factors in scare events. Implications for risk communication and for future research on risk and public health are discussed. Keywords: Health scare, Social amplification of risk, Expert, Media, Risk controversyfunded by the Sidney Sax Travelling Postdoctoral Research Fellowship in Public Health, National Health and Medical Research Council, Australia

Klimaat onderzoek bij het Nederlands Instituut voor Onderzoek der Zee

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Refractive and visual outcomes of femtosecond laser-assisted cataract surgery

Objective: To compare refractive and visual acuity outcomes of femtosecond laser-assisted cataract surgery (FLACS) to manual surgery. Participants: Consecutive series of patients in a private ophthalmic practice in Sydney, with 337 eyes undergoing FLACS on the LenSx platform and 230 eyes manual cataract surgery. Main Outcome Measures: Astigmatism, surgically-induced corneal astigmatism, achievement of target refraction and corrected and uncorrected distance visual acuity (UDVA). Results: The FLACS group had statistically less mean residual post-operative astigmatism by 0.18D (p<0.001) than the manual group. The femtosecond laser produced equivalent mean magnitude and variability of surgically-induced corneal astigmatism compared to manual cataract surgery. Both surgical methods had equivalent achievement of target spherical equivalent (69% within 0.5 D of target refraction, p=0.911). In eyes with good visual potential and an emmetropic target, post-operative UDVA was statistically better in the femtosecond group with an average improvement of 2.4 logMAR letters (p=0.020). Conclusions: Femtosecond cataract surgery produced less residual post-operative refractive astigmatism and better unaided distance visual acuity compared to manual cataract surgery. However there was no improvement in the achievement of target post-operative refraction

Design and Topology Optimisation of Tissue Scaffolds

Tissue restoration by tissue scaffolding is an emerging technique with many potential applications. While it is well-known that the structural properties of tissue scaffolds play a critical role in cell regrowth, it is usually unclear how optimal tissue regeneration can be achieved. This thesis hereby presents a computational investigation of tissue scaffold design and optimisation. This study proposes an isosurface-based characterisation and optimisation technique for the design of microscopic architecture, and a porosity-based approach for the design of macroscopic structure. The goal of this study is to physically define the optimal tissue scaffold construct, and to establish any link between cell viability and scaffold architecture. Single-objective and multi-objective topology optimisation was conducted at both microscopic and macroscopic scales to determine the ideal scaffold design. A high quality isosurface modelling technique was formulated and automated to define the microstructure in stereolithography format. Periodic structures with maximised permeability, and theoretically maximum diffusivity and bulk modulus were found using a modified level set method. Microstructures with specific effective diffusivity were also created by means of inverse homogenisation. Cell viability simulation was subsequently conducted to show that the optimised microstructures offered a more viable environment than those with random microstructure. The cell proliferation outcome in terms of cell number and survival rate was also improved through the optimisation of the macroscopic porosity profile. Additionally artificial vascular systems were created and optimised to enhance diffusive nutrient transport. The formation of vasculature in the optimisation process suggests that natural vascular systems acquire their fractal shapes through self-optimisation

Good results with cemented total hip arthroplasty in patients between 40 and 50 years of age: 168 hips followed for 2–19 years

Background and purpose Total hip arthroplasties in young patients have lower long-term survival rates than in older patients. We evaluated the use of a unique treatment protocol in patients aged between 40 and 50 years. In all cases we used a cemented THA, and for acetabular deficiencies we also used impacted bone grafts together with a cemented cup