Stephan Imfeld

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Technological advances of position aware devices lead to a wealth of data documenting the lifelines of GPS-tracked animals, people, or vehicles. The integration of knowledge discovery techniques in GIS is thus an important research field with respect to the emerging volumes of tracking data. The motivation of this research is to find patterns in the way(More)
The overall goal of the ongoing project is to develop methods for spatio-temporal analysis of relative motion within groups of moving point objects, e.g. GPS-tracked animals. Whereas recent efforts of dealing with dynamic phenomena within the GIScience community mainly concentrated on modeling and representation, this research project concentrates on the(More)
PURPOSE Colour coded duplex sonography (DS) is widely used for the assessment of renal artery stenosis (RAS). Different criteria have been specified for the detection of significant RAS. The aim of our study was to compare routinely used DS criteria, both with intra-arterial pressure gradients and arteriographic degree of stenosis, and to validate different(More)
The use of contrast-enhanced ultrasound (CEUS) for vascular imaging indications has increased dramatically during the last decade. Ultrasound contrast agents are gas-filled microbubbles that are injected into the bloodstream and serve as strict intravascular reflectors of ultrasound waves. Numerous studies have addressed the potential clinical use of CEUS(More)
OBJECTIVES We sought to validate a new noninvasive technique to determine central venous pressure (CVP) using high-resolution compression sonography. BACKGROUND Information concerning CVP is crucial in clinical situations, including cardiac failure, volume overload, and sepsis. The measurement of CVP, however, requires puncture of a vein with attendant(More)
The traditional treatment of venous thromboembolism (VTE) has been use of heparin and vitamin K antagonists (VKA), and although shown to be effective, they have numerous limitations. New oral anticoagulants (NOACs) including direct thrombin (factor IIa) inhibitors (dabigatran) and selective factor Xa inhibitors (rivaroxaban, apixaban and edoxaban) have(More)
Global positioning systems (GPS) are likely to revolutionize animal telemetry studies. GPS collars allow biologists to collect systematically scheduled data when VHF telemetry data is difficult or impossible to collect. Past studies have shown that the success of GPS telemetry is greater when animals are standing, or in open habitats. To make effective use(More)
BACKGROUND The magnitude of potential changes in Quality-of-Life (QoL) after structured institution-based or home-based peripheral arterial disease (PAD) rehabilitation programs are largely unknown at present. This pilot study provides first QoL data after PAD rehabilitation or a home-based PAD training. PATIENTS AND METHODS In a non-randomized,(More)
PURPOSE To prospectively evaluate the accuracy of noninvasive central venous pressure (CVP) assessment by compression ultrasound of a forearm vein (CUS), inferior vena cava (IVC-C) and internal jugular vein collapsibility (IJV-C) compared to invasive CVP measurement (invCVP) as the gold standard. MATERIALS AND METHODS CUS, IVC-C and IJV-C were performed(More)