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Increasing Scots pine (Pinus sylvestris L.) mortality has been recently observed in the dry inner valleys of the European Alps. Besides drought, infection with pine mistletoe (Viscum album ssp. austriacum) seems to play an important role in the mortality dynamics of Scots pines, but how mistletoes promote pine decline remains unclear. To verify whether pine mistletoe infection weakens the host via crown degradation, as observed for dwarf mistletoes, we studied the negative effects of pine mistletoe infestation on the photosynthetic tissues and branch growth of pairs of infested and non-infested branches. Pine mistletoe infection leads to crown degradation in its host by reducing the length, the radial increment, the ramification, the needle length and the number of needle years of the infested branches. This massive loss in photosynthetic tissue results in a reduction in primary production and a subsequent decrease in carbohydrate availability. The significant reduction in needle length due to mistletoe infection is an indication for a lower water and nutrient availability in infested branches. Thus, mistletoe infection might lead to a decrease in the availability of water and carbohydrates, the two most important growth factors, which are already shortened due to the chronic drought situation in the area. Therefore, pine mistletoe increases the risk of drought-induced mortality of its host when growing in a xeric environment.
Purpose of Study: Thrombosis-related complications are among the leading causes for morbidity and mortality in patients who depend on artificial organs. For the prediction of platelet behavior both the flow conditions inside the device and the thrombogenic properties of the blood-contacting surfaces must be considered. Platelet reactions under the influence of well-defined shear rates are experimentally evaluated and numerically simulated. The approach is intended for the analysis of VAD and oxygenator design.
Methods Used: A mathematical model of platelet activation, adhesion and aggregation has been implemented into a finite element CFD (Computational Fluid Dynamics) code. The approach is based on the advective and diffusive transport equations for resting and activated platelets and platelet released agonists. Experiments with citrate-anticoagulated freshly-drawn whole blood are performed in a perfusion flow chamber as well as in a system of rotating cylinders for Couette and Taylor-vortex flow. Different biomaterials are used. The activation, adhesion and aggregation are quantified using scanning electron microscopy and flow cytometry.
Summary of Results: Regions and flow conditions with a high potential for thrombus growth could be identified. The experiments clearly show the influence of the blood contacting material and governing shear rates. Numerical analysis can explain observed adhesion patterns and the degree of thrombus formation
Ein lichtadressierbarer potentiometrischer Sensor (LAPS) kann die Konzentration eines oder mehrerer Analyten ortsaufgelöst auf der Sensoroberfläche nachweisen. Dazu wird mit einer modulierten Lichtquelle die Halbleiterstruktur des zu untersuchenden Bereiches angeregt und ein entsprechender Photostrom ausgelesen. Durch gleichzeitige Anregung mehrere Bereiche durch Lichtquellen mit unterschiedlichen Modulationsfrequenzen können diese auch zeitgleich ausgelesen werden. Mit der neuen, hier vorgestellten Ansteuerungselektronik integriert in einem "Field Programmable Gate Array" (FPGA) ist es möglich, mehrere Leuchtquellen gleichzeitig mit unterschiedlichen, während der Laufzeit festlegbaren Frequenzen, Phasen und Lichtintensitäten zu betreiben. Somit kann das Frequenzverhalten des Sensors untersucht und die Konzentration des Analyten über das Oberflächenpotential mit Hilfe von Strom/Spannungs-Kurven und Phase/Spannungs-Kurven bestimmt werden.