74 research outputs found
A low perfusion rate microreactor for continuous monitoring of enzyme characteristics: application to glucose oxidase
This report describes a versatile and robust microreactor for bioactive proteins physically immobilized on a polyether sulfone filter. The potential of the reactor is illustrated with glucose oxidase immobilized on a filter with a cut-off value of 30Â kDa. A flow-injection system was used to deliver the reactants and the device was linked on-line to an electrochemical detector. The microreactor was used for on-line preparation of apoglucose oxidase in strong acid and its subsequent reactivation with flavin adenine dinucleotide. In addition we describe a miniaturized version of the microreactor used to assess several characteristics of femtomole to attomole amounts of glucose oxidase. A low negative potential over the electrodes was used when ferrocene was the mediator in combination with horseradish peroxidase, ensuring the absence of oxidation of electro-active compounds in biological fluids. A low backpressure at very low flow rates is an advantage, which increases the sensitivity. A variety of further applications of the microreactor are suggested
Cooperation, Norms, and Revolutions: A Unified Game-Theoretical Approach
Cooperation is of utmost importance to society as a whole, but is often
challenged by individual self-interests. While game theory has studied this
problem extensively, there is little work on interactions within and across
groups with different preferences or beliefs. Yet, people from different social
or cultural backgrounds often meet and interact. This can yield conflict, since
behavior that is considered cooperative by one population might be perceived as
non-cooperative from the viewpoint of another.
To understand the dynamics and outcome of the competitive interactions within
and between groups, we study game-dynamical replicator equations for multiple
populations with incompatible interests and different power (be this due to
different population sizes, material resources, social capital, or other
factors). These equations allow us to address various important questions: For
example, can cooperation in the prisoner's dilemma be promoted, when two
interacting groups have different preferences? Under what conditions can costly
punishment, or other mechanisms, foster the evolution of norms? When does
cooperation fail, leading to antagonistic behavior, conflict, or even
revolutions? And what incentives are needed to reach peaceful agreements
between groups with conflicting interests?
Our detailed quantitative analysis reveals a large variety of interesting
results, which are relevant for society, law and economics, and have
implications for the evolution of language and culture as well
Locally weighted interpolating growing neural gas
In this paper, we propose a new approach to function approximation based on a growing neural gas (GNG), a self-organizing map (SOM) which is able to adapt to the local dimension of a possible high-dimensional input distribution. Local models are built interpolating between values associated with the map's neurons. These models are combined using a weighted sum to yield the final approximation value. The values, the positions, and the "local ranges" of the neurons are adapted to improve the approximation quality. The method is able to adapt to changing target functions and to follow nonstationary input distributions. The new approach is compared to the radial basis function (RBF) extension of the growing neural gas and to locally weighted projection regression (LWPR), a state-of-the-art algorithm for incremental nonlinear function approximation
LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION FOR THE DETERMINATION OF CHOLINE AND ACETYLCHOLINE IN PLASMA AND RED BLOOD-CELLS - FAILURE TO DETECT ACETYLCHOLINE IN BLOOD OF HUMANS AND MICE
AUTOMATED ASSAY OF TRYPTOPHAN AT NANOGRAM LEVEL - DETERMINATION OF TRYPTOPHAN IN CEREBROSPINAL-FLUID AND OF TOTAL AND NON-PROTEIN BOUND TRYPTOPHAN IN SERUM
LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION FOR THE DETERMINATION OF CHOLINE AND ACETYLCHOLINE IN PLASMA AND RED BLOOD-CELLS - FAILURE TO DETECT ACETYLCHOLINE IN BLOOD OF HUMANS AND MICE
LIQUID-CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION FOR THE DETERMINATION OF CHOLINE AND ACETYLCHOLINE IN PLASMA AND RED BLOOD-CELLS - FAILURE TO DETECT ACETYLCHOLINE IN BLOOD OF HUMANS AND MICE
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