Wirtschaftlichkeitsprognose und kontrolle von IT-Investitionen: Abschlussbericht und Fallbeispiel

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Schutz oder Schaden für die Gefäße? : Bei Sauerstoffradikalen kommt es auf das Gleichgewicht an

Sauerstoffradikale werden für Alterung, Krebs und Herz-Kreislauf-Erkrankungen verantwortlich gemacht. Von diesem schlechten Image profitiert der große Markt der Nahrungszusatzstoffe wie Vitamine, die Radikale im Körper einfangen. Doch in klinischen Studien können keine positiven Effekte durch die Einnahme von Vitaminpräparaten nachgewiesen werden. Warum? Weil Sauerstoffradikale nicht nur schädliche Nebenprodukte des Stoffwechsels sind, sondern auch lebensnotwendige Funktionen wie die Abwehr von Krankheitserregern übernehmen. Sie werden daher im Körper in einem eng regulierten Bereich aktiv produziert. Unsere Arbeitsgruppe am Institut für Kardiovaskuläre Physiologie untersucht Mechanismen der Radikalproduktion durch Nox-Enzyme und erforscht ihre physiologische Bedeutung im Herz-Kreislauf-System

Konzept zur Nutzenbewertung von IT-Investitionen

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Open-pore sintered glass-ceramics as carrier material for biotechnological use

Open-pore carriers with defined open porosity up to 45 % for biotechnological use were manufactured by sintering and crystallization of glass powders of cordierite stoichiometry. The stop of the shrinkage caused by a surface crystallization of the glass ("sinter blockade") is utilized to stabilize a desired pore volume without filier or foaming aids. Glass powders of the stoichiometric composition of cordierite (2MgO · 2AI₂O₃ · 5SiO₂) with different grain size distributions were used as starting materials. The efficiency of the sinter blockade and thereby the stabilized porosity of the resulting compact mainly depends on the surface nucleation density at the Single glass particles which can be adjusted by powder processing. Furtheron, the chosen grain size distribution of the glass powders and the sintering process parameters (heating rate, temperature, heating time) are important factors to control the sintering behaviour. Samples of carrier bodies produced by this way are tested and evaluated quantitatively as carriers for biofilms in a biotechnological process for decomposition of pollutants in a synthetic model waste water system

Detecting dominant changes in irregularly sampled multivariate water quality data sets

Time series of groundwater and stream water quality often exhibit substantial temporal and spatial variability, whereas typical existing monitoring data sets, e.g. from environmental agencies, are usually characterized by relatively low sampling frequency and irregular sampling in space and/or time. This complicates the differentiation between anthropogenic influence and natural variability as well as the detection of changes in water quality which indicate changes in single drivers. We suggest the new term "dominant changes" for changes in multivariate water quality data which concern (1) multiple variables, (2) multiple sites and (3) long-term patterns and present an exploratory framework for the detection of such dominant changes in data sets with irregular sampling in space and time. Firstly, a non-linear dimension-reduction technique was used to summarize the dominant spatiotemporal dynamics in the multivariate water quality data set in a few components. Those were used to derive hypotheses on the dominant drivers influencing water quality. Secondly, different sampling sites were compared with respect to median component values. Thirdly, time series of the components at single sites were analysed for long-term patterns. We tested the approach with a joint stream water and groundwater data set quality consisting of 1572 samples, each comprising sixteen variables, sampled with a spatially and temporally irregular sampling scheme at 29 sites in northeast Germany from 1998 to 2009. The first four components were interpreted as (1) an agriculturally induced enhancement of the natural background level of solute concentration, (2) a redox sequence from reducing conditions in deep groundwater to post-oxic conditions in shallow groundwater and oxic conditions in stream water, (3) a mixing ratio of deep and shallow groundwater to the streamflow and (4) sporadic events of slurry application in the agricultural practice. Dominant changes were observed for the first two components. The changing intensity of the first component was interpreted as response to the temporal variability of the thickness of the unsaturated zone. A steady increase in the second component at most stream water sites pointed towards progressing depletion of the denitrification capacity of the deep aquifer