Impact modelling studies for a three-wheeled scooter taxi.

Three-wheeled scooter taxis (TSTs) are being used in many Asian countries and along with buses are the main mode of public transport for the urban middle class population. The TST chassis is made by the manufacturer and the body is fabricated by local body-makers. The vehicle is not subject to any crash safety specifications. This work is the first attempt to study the crash characteristics of TSTs using a crash simulation computer software (MADYMO) with the objective of developing practical guidelines to make the vehicle safer in collisions with other motorized road users and pedestrians. Impact modelling was done for the standard and modified TST occupied by a driver and one passenger at impact velocities of 10-30 km/h crashing with a pedestrian and a bus front. The results show that the passenger and the driver of the standard TST can sustain high HICs, face/head contact forces and tibia/knee contact forces in crashes with buses at velocities 20 km/h and greater. The magnitude of these parameters can be reduced slightly by small changes in the design of the interior and padding of critical surfaces. To increase the safety of the TST significantly major modifications need to be incorporated in the design of TSTs and bus fronts. Pedestrian impact simulations indicate that it may be possible to reduce the impact forces by changing the shape of the front of the TST. The results indicate that it should be possible to improve the crash safety properties of vehicles indigenously designed in Asian and African countries by the use of crash simulation models like MADYMO. This procedure is relatively inexpensive and can provide the first approximations for design of safer vehicles.

Design and analysis of robust total joint replacements: finite element model experiments with environmental variables.

Computer simulation of orthopaedic devices can be prohibitively time consuming, particularly when assessing multiple design and environmental factors. Chang et al. (1999) address these computational challenges using an efficient statistical predictor to optimize a flexible hip implant, defined by a midstem reduction, subjected to multiple environmental conditions. Here, we extend this methodology by: (1) explicitly considering constraint equations in the optimization formulation, (2) showing that the optimal design for one environmental distribution is robust to alternate distributions, and (3) illustrating a sensitivity analysis technique to determine influential design and environmental factors. A thin midstem diameter with a short stabilizing distal tip minimized the bone remodeling signal while maintaining satisfactory stability. Hip joint force orientation was more influential than the effect of the controllable design variables on bone remodeling and the cancellous bone elastic modulus had the most influence on relative motion, both results indicating the importance of including uncontrollable environmental factors. The optimal search indicated that only 16 to 22 computer simulations were necessary to predict the optimal design, a significant savings over traditional search techniques.

Pulmonary toxicity of induction chemotherapy prior to standard or high-dose chemotherapy with autologous hematopoietic support.

We closely followed the pulmonary function of 150 consecutive high-risk breast cancer patients who underwent standard induction CAF (cyclophosphamide, doxorubicin, 5-fluorouracil) chemotherapy, followed by randomization to either standard-dose CPB (cyclophosphamide, cisplatin, bischloroethylnitrosourea [BCNU]) chemotherapy (SDC) or to high-dose CPB chemotherapy (HDC) with autologous bone marrow transplantation (ABMT) and peripheral blood progenitor cell support (PBPCS). Previously, we have described a delayed pulmonary toxicity syndrome (DPTS) which characterizes the pulmonary dysfunction after HDC and ABMT in this patient population. However, little is known concerning the role induction chemotherapy plays in its development. We found that after three cycles of induction CAF, the mean diffusing capacity of the lungs for carbon monoxide (DL(CO)) significantly decreased by 12.6%. Additionally, in patients receiving HDC, the mean DL(CO) further decreased to a nadir of 55.2 +/- 14.1% which was significantly lower than those receiving SDC (nadir: 80.7 +/- 12.3%). DPTS occurred in 72% of patients receiving HDC as compared with only 4% of patients receiving SDC. All individuals diagnosed with DPTS were treated with prednisone and the 2-yr follow-up of pulmonary function revealed a gradual improvement in mean DL(CO) such that there were no differences between HDC and SDC groups at the end of the study. No mortality was attributable to pulmonary toxicity in either group. After induction chemotherapy, but before HDC, bronchoalveolar lavage (BAL) demonstrated significant elevations in interleukin-6 (IL-6), IL-8, neutrophils, and lymphocytes. We conclude that induction CAF produces asymptomatic pulmonary dysfunction and inflammation which may prime the lungs for further injury by HDC and predispose to the development of DPTS. Fortunately, in this specific ABMT patient population, the early and judicious use of prednisone appears to improve pulmonary function in patients who develop DPTS.