Measuring range of active cervical rotation in a position of full head flexion using the 3D Fastrak measurement system: an intra-tester reliability study

Most external assessments of cervical range of motion assess the upper and lower cervical regions simultaneously. This study investigated the within and between days reliability of the clinical method used to bias this movement to the upper cervical region, namely measuring rotation of the head and neck in a position of full cervical flexion. Measurements were made using the Fastrak measurement system and were conducted by one operator. Results indicated high levels of within and between days repeatability (range of ICC2,1 values: 0.85-0.95). The ranges of axial rotation to right and left, measured with the neck positioned in full flexion, were approximately 56% and 50%, respectively of total cervical rotation, which relates well to the proportional division of rotation in the upper and lower cervical regions. These results suggest that this method of measuring rotation would be appropriate for use in subject studies where movement dysfunction is present in the upper cervical region, such as those with cervicogenic headache. (C) 2003 Elsevier Science Ltd. All rights reserved.

Respiratory health effects of cannabis: Position statement of the Thoracic Society of Australia and New Zealand

Both the gaseous and the particulate phases of tobacco and cannabis smoke contain a similar range of harmful chemicals. However, differing patterns of inhalation mean that smoking a 'joint' of cannabis results in exposure to significantly greater amounts of combusted material than with a tobacco cigarette. The histopathological effects of cannabis smoke exposure include changes consistent with acute and chronic bronchitis. Cellular dysplasia has also been observed, suggesting that, like tobacco smoke, cannabis exposure has the potential to cause malignancy. These features are consistent with the clinical presentation. Symptoms of cough and early morning sputum production are common (20-25%) even in young individuals who smoke cannabis alone. Almost all studies indicate that the effects of cannabis and tobacco smoking are additive and independent. Public health education should dispel the myth that cannabis smoking is relatively safe by highlighting that the adverse respiratory effects of smoking cannabis are similar to those of smoking tobacco, even although it remains to be confirmed that smoking cannabis alone leads to the development of chronic lung disease.

Biaxial failure model for fiber reinforced concrete

Steel fiber reinforced concrete (SFRC) is widely applied in the construction industry. Numerical elastoplastic analysis of the macroscopic behavior is complex. This typically involves a piecewise linear failure curve including corner singularities. This paper presents a single smooth biaxial failure curve for SFRC based on a semianalytical approximation. Convexity of the proposed model is guaranteed so that numerical problems are avoided. The model has sufficient flexibility to closely match experimental results. The failure curve is also suitable for modeling plain concrete under biaxial loading. Since this model is capable of simulating the failure states in all stress regimes with a single envelope, the elastoplastic formulation is very concise and simple. The finite element implementation is developed to demonstrate the conciseness and the effectiveness of the model. The computed results display good agreement with published experimental data.

Unsaturated diffusivity functions for concrete derived from NMR images

Deterioration of concrete or reinforcing steel through excessive contaminant concentration is often the result of repeated wetting and drying cycles. At each cycle, the absorption of water carries new contaminants into the unsaturated concrete. Nuclear Magnetic Resonance (NMR) is used with large concrete samples to observe the shape of the wetting profile during a simple one-dimensional wetting process. The absorption of water by dry concrete is modelled by a nonlinear diffusion equation with the unsaturated hydraulic diffusivity being a strongly nonlinear function of the moisture content. Exponential and power functions are used for the hydraulic diffusivity and corresponding solutions of the diffusion equation adequately predict the shape of the experimental wetting profile. The shape parameters, describing the wetting profile, vary little between different blends and are relatively insensitive to subsequent re-wetting experiments allowing universal parameters to be suggested for these concretes.