Three dimensional finite element modelling of metatarsal stresses during running.

Second metatarsal stress fractures are a problematic injury for runners and are formed when the rate of repair of bone is outpaced by the damage accumulated during loading. Measuring the peak stresses on the bone during running gives an indication of damage accumulation but direct measurement is invasive. Finite element modelling is a viable alternative method of accurately estimating bone stresses but tends to be too computationally expensive for use in applied research. This study presents a novel and simple finite element model which can estimate bone stresses on the second metatarsal during the stance phase of walking and running, accounting for joint reaction forces and soft tissue effects. The influence of the forces and kinematic inputs to the model and the presence of the soft tissues was quantified using a sensitivity analysis. The magnitudes of maximum stress from the model are similar to existing finite element models and bone staple strain gauge values collected during walking and running. The model was found to be most sensitive to the pitch angle of the metatarsal and the joint reaction forces and was less sensitive to the ground reaction forces under the metatarsal head, suggesting that direct measurement of external forces should not be assumed to represent internal stresses.

Development of a conceptual framework of holistic risk assessment - Landfill as a particular type of contaminated land.

Landfills can be regarded as a particular type of contaminated land that has a potential to directly and indirectly pollute all of the four main spheres of the environment which are the lithosphere, atmosphere, hydrosphere and eventually adversely impact the biosphere. Therefore, environmental risk assessment of a landfill has to be more integrated and holistic by virtue of its nature of being a multidimensional pollutant source. Despite this, although various risk assessment approaches have been adopted for landfill waste disposal sites, there are still wide-ranging knowledge gaps and limitations which need to be addressed. One important knowledge gap and limitation of current risk assessment approaches is the inability to fully identify, categorise and aggregate all individual risks from all combinations of hazards, pathways and targets/receptors (e.g. water, air, soil and biota) in connection to a certain landfill leachate and yet at any stage of the landfill cycle. So such an approach is required that could not only integrate all possible characteristics of varying scenarios but also contain the ability to establish an overall risk picture, irrespective of the lifecycle stage of the landfill (e.g. planning stage/pre-operation, in-operation or post-operation/closed). One such approach to address the wide-breadth of landfill impact risks is by developing a more holistic risk assessment methodology, whose conceptual framework is presented in this paper for landfill leachate in a whole-system format. This conceptual framework does not only draw together various constituting factors and sub-factors of risk assessment in a logical sequence and categorical order, but also indicates the "what, why, when and how" outputs of and inputs to these factors and sub-factors can be useful. The framework is designed to identify and quantify a range of risks associated with all stages of the landfill lifecycle, and yet in a more streamlined, logical, categorical and integrated format, offering a more standardised and unified whole-system approach.

Removal of MTBE from a clay soil using electrokinetic technique.

Remediation of a soil contaminated with methyl tertiary butyl ether (MTBE) was studied by using the electrokinetic technique. A series of experimental tests were carried out on contaminated soil in an electro-osmotic apparatus at different applied gradients of voltage and time. The tests were conducted with distilled water and ethylenediaminetetra acetic acid (EDTA) solution as electrolyte. During each test the values of pH at anode and cathode reservoirs and also the discharge from cathode were measured. At the end of each test a number of soil samples were extracted from the middle of the soil at different distances from the anode and the removal of contaminant was measured by a gas chromatography apparatus. The results indicate that with EDTA as electrolyte the highest efficiency for removal of MTBE is achieved with 2.0 V/cm gradient and in the duration of 14 days. In addition, EDTA causes the values of pH to increase and decrease in the cathode and anode reservoirs, respectively. It also decreases the effluent and electro-osmotic permeability in comparison with distilled water. Experimental data were analysed by ANOVA and t-test methods. These statistical analyses showed significant difference (at 5% level) between the reference and other tests.

Literature review of baseline study for risk analysis - the landfill leachate case.

There is growing awareness and public concern about environmental impacts of waste management and disposal. Environmental policy instruments have been strengthened and associated governmental programmes have increased in recent years, resulting in high level strategies for waste management. Risk assessment is now an essential tool in the prioritisation of environmental and human health protection. However, regulators need to compare the full range of risks on a sound and consistent basis. Comparing risks from such diverse sources poses a significant challenge, and traditional hazard and risk assessments are no longer sufficient. Consideration now needs to be given to a much wider range of factors if risk assessment is to be used as an aid to more integrated decision-making process. For this purpose, baseline study - the foundation of risk assessment - can play a crucial role. To date limited research has been conducted on the need, parameters, requirements, and constituents of baseline study particularly in the context of how, why, and what information is to be collated in order to render risk assessments more appropriately integrated and complete. To establish the 'state-of-the-art' of baseline study, this paper comprehensively reviews the literature regarding environmental risk assessment in general terms, and then proceeds to review work that is specifically related to landfills and landfill leachate, thereby identifying knowledge gaps and shortfall areas. This review concludes that a holistic baseline study procedure for waste disposal sites, which risk assessors could use for carrying out risk analyses specifically for landfill leachate, does not as yet exist.

Finite element modeling of contaminant transport in soils including the effect of chemical reactions.

The movement of chemicals through soils to the groundwater is a major cause of degradation of water resources. In many cases, serious human and stock health implications are associated with this form of pollution. Recent studies have shown that the current models and methods are not able to adequately describe the leaching of nutrients through soils, often underestimating the risk of groundwater contamination by surface-applied chemicals, and overestimating the concentration of resident solutes. Furthermore, the effect of chemical reactions on the fate and transport of contaminants is not included in many of the existing numerical models for contaminant transport. In this paper a numerical model is presented for simulation of the flow of water and air and contaminant transport through unsaturated soils with the main focus being on the effects of chemical reactions. The governing equations of miscible contaminant transport including advection, dispersion-diffusion and adsorption effects together with the effect of chemical reactions are presented. The mathematical framework and the numerical implementation of the model are described in detail. The model is validated by application to a number of test cases from the literature and is then applied to the simulation of a physical model test involving transport of contaminants in a block of soil with particular reference to the effects of chemical reactions. Comparison of the results of the numerical model with the experimental results shows that the model is capable of predicting the effects of chemical reactions with very high accuracy. The importance of consideration of the effects of chemical reactions is highlighted.

Spinal tuberculosis: a major public health hazard in Isfahan.

The purpose of this study is to review of spinal tuberculosis in three hospitals in Isfahan of Iran. We carried out a cross sectional study of 630 patients with tuberculosis and identified 100 patients with spinal involvement in the three hospitals. Tuberculosis was diagnosed based on one of a compatible clinical picture. A radiographic study of the spine with suspicious signs and skin tested were performed for each patient. Demographic data, sign, symptoms and site of spinal involvement were recorded. In all patients, a chest X ray and sputum smear and culture was performed for rouling out of pulmonary tuberculosis. Out of the 100 patients with spinal tuberculosis, 58% were male and 42% were female. Main symptoms were spinal deformity, local tenderness and neurologic deficits. Fever and constitutional symptoms were in 80% of cases. Only 68% had a positive tuberculin skin test. Three percent involvement were the upper thoracic spine, 23% the lower thoracic spine, 69% also the lower thoracic, T12 and upper lumbar spines, (thoracolumbar) and 5% the cervical spine. 40 cases underwent bone biopsy that 25% had a positive smear, whereas 62.5% had a positive culture. Histologic findings suggestive of tuberculosis involvement of the bone were found in 37 of the 40 biopsies. The most common age for spinal involvement were 20-40 years (p < 0.05). Spinal tuberculosis may be missed in patients with no evidence of pulmonary. No pathognomonic imaging signs allow tuberculosis to be readily distinguished from other conditions. In this here, we discuss about clinical and histopathological findings in patients with spinal tuberculosis.