Medical imaging and clinical studies have proven that the heart pumps by means of minor outer volume changes and back-and-forth longitudinal movements in the atrioventricular (AV) region. The magnitude of AV-plane displacement has also shown to be a reliable index for diagnosis of heart failure. Despite this, AV-plane displacement is usually omitted from cardiovascular modelling. We present a lumped-parameter cardiac model in which the heart is described as a displacement pump with the AV plane functioning as a piston unit (AV piston). This unit is constructed of different upper and lower areas analogous with the difference in the atrial and ventricular cross-sections. The model output reproduces normal physiology, with a left ventricular pressure in the range of 8-130 mmHg, an atrial pressure of approximatly 9 mmHg, and an arterial pressure change between 75 mmHg and 130 mmHg. In addition, the model reproduces the direction of the main systolic and diastolic movements of the AV piston with realistic velocity magnitude (similar to 10 cm/s). Moreover, changes in the simulated systolic ventricular-contraction force influence diastolic filling, emphasizing the coupling between cardiac systolic and diastolic functions. The agreement between the simulation and normal physiology highlights the importance of myocardial longitudinal movements and of atrioventricular interactions in cardiac pumping.

Previous research has shown that wheelchair-seated passengers using special transportation services (STS) have been injured without being involved in a vehicle crash. In order to estimate incident rate andsocietal costs for these vehicle-related injuries, the focus needs to be adjusted towards a traveler/incidentoriented perspective. The aim of the project was to utilize such a perspective, related to travelers using STS in Sweden. In order to address the chosen perspective, a mixed method approach was used, involving quantitative as well as qualitative research techniques applied on four different sets of data: one hospital-based record,two sets of STS incident report databases, and interviews with wheelchair-seated STS passengers. The results showed that the injury incidence rate in STS is considerable, i.e. 10 per 100,000 trips. However, this high incidence rate is not due to road traffic collisions, but to non-collision injury incidents involving many elderly and frail passengers, who easily sustain traumas ranging from minor to moderate. The costs were estimated to be 23 million USD per annum or 14 USD per trip. Results suggest that future injury prevention measures should focus on safety in boarding and alighting procedures, as well as thecontinuing development of WTORS.

Previous research has pointed out that non-collision injuries occur among wheelchair users in Special Transportation Services (STS – a demand-responsive transport mode). The organization of such modesis also quite complex, involving both stakeholders and key personnel at different levels. Our objectivewas therefore to qualitatively explore the state of safety, as perceived and discussed within a workplace context. Focus groups were held with drivers of both taxi companies and bus companies. The results indicated that passengers run the risk of being injured without being involved in a vehicle collision. The pertinent organizational and corporate culture did not prioritize safety. The drivers identifiedsome relatively clear-cut safety threats, primarily before and after a ride, at vehicle standstill. The driver’s work place seemed to be surrounded with a reactive instead of proactive structure. We conclude that not only vehicle and wheelchair technical safety must be considered in STS, butalso system safety. Instead of viewing drivers’ error as a cause, it should be seen as a symptom of systems failure. Human error is connected to aspects of tools, tasks, and operating environment. Enhanced understanding and influence of these connections within STS and accessible public transport systemswill promote safety for wheelchair users.