Tobias Heldt

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We hypothesise that differences in people s attitudes and personality traits lead them to attribute varying importance to environmental considerations, safety, comfort, convenience and flexibility. Differences in personality traits can be revealed not only in the individuals choice of transport, but also in other actions of their everyday lives—such as how(More)
We present an algorithm that automatically computes the QT interval duration from body surface electrocardiograms (ECGs). The algorithm consists of three processing steps: (1) PQ junction detection, (2) optimal lead selection, and (3) T-wave end detection. A previously developed algorithm for QRS detection was employed to detect the onset of each QRS(More)
A global system model of the systemic circulation is combined with a local finite element solution to simulate blood flow in a stenosed coronary artery. Local fluid dynamic issues arise in connection with the detailed flow patterns within the stenosed coronary artery while the global system model is used to simulate the response of the rest of the(More)
Orthostatic intolerance following spaceflight remains a critical problem in the current life-science space program. The study presented in this paper is part of an ongoing effort to use mathematical models to investigate the effects of gravitational stresses on the cardiovascular system of normals and microgravity adapted individuals. We employ a twelve(More)
In a natural experiment, this paper studies the impact of an informal sanctioning mechanism on individuals’ voluntary contribution to a public good. Cross-country skiers’ actual cash contributions in two ski resorts, one with and one without an informal sanctioning system, are used. I find the contributing share to be higher in the informal sanctioning(More)
The work presented in this paper is part of an ongoing effort to use mathematical models to investigate the effects of microgravity on the cardiovascular system. In particular, a thirteen compartment lumped parameter representation of the cardiovascular system is used to simulate some of the current hypotheses concerning the mechanism of post-flight(More)
Lumped-parameter models of the cardiovascular system have been used extensively in the past, especially when coupled to time-varying elastance (or compliance) representations of ventricular contraction. In this paper, we use a physiologically motivated approximation to the timevarying compliance waveform to derive analytical solutions to the short-term(More)
This paper presents a cardiovascular model that is capable of simulating the short-term (< or approximately equal to 3 min) transient hemodynamic response to gravitational stress and a gradient-based optimization method that allows for the automated estimation of model parameters from simulated or experimental data. We perform a sensitivity analysis of the(More)
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