Modeling Calcium Concentration and Biochemical Reactions

Almost all regions of the brain receive one or more neuromodulatory inputs, and disrupting these inputs produces deficits in neuronal function. Neuromodulators act through intracellular second messenger pathways to influence the electrical properties of neurons, integration of synaptic inputs, spatio-temporal firing dynamics of neuronal networks, and, ultimately, systems behavior. Second messengers pathways consist of series of bimolecular reactions, enzymatic reactions, and diffusion. Calcium is the second messenger molecule with the most effectors, and thus is highly regulated by buffers, pumps and intracellular stores. Computational modeling provides an innovative, yet practical method to evaluate the spatial extent, time course and interaction among second messenger pathways, and the interaction of second messengers with neuron electrical properties. These processes occur both in compartments where the number of molecules are large enough to describe reactions deterministically (e.g. cell body), and in compartments where the number of molecules is small enough that reactions occur stochastically (e.g. spines). – In this tutorial, I explain how to develop models of second messenger pathways and calcium dynamics. The first part of the tutorial explains the equations used to model bimolecular reactions, enzyme reactions, calcium release channels, calcium pumps and diffusion. The second part explains some of the GENESIS, Kinetikit and Chemesis objects that implement the appropriate equations. In depth explanation of calcium and second messenger models is provided by reviewing code, both in XPP, Chemesis and Kinetikit, that implements simple models of calcium dynamics and second messenger cascades.

Marked Silence, Neo-Feudalistic Reactions and the Stabilized Moral Regime – The Current De- and Reformation of „the Social“

The German chancellor and leader of the German conservative party, Angela Merkel, said in an interview a few weeks ago: “Nobody could have imagined a few months ago to what extent we would be pushed into state intervention programs. Of course, Merkel spoke on, this intervention is not easy for anybody. Therefore, she recommended turning back to the former course as soon as possible” (tagesschau.de, 11. März 2008, zit. nach Bildzeitungsinterview mit Angela Merkel, own translation). The worldwide celebrated new president of the United States, Barack Obama, said in an interview on CBS-News a few weeks before Merkel: “(...) there's no doubt that we have not been able yet to reset the confidence in the financial markets and in the consumer markets and among businesses that allow the economy to move forward in a strong way. And my job as president is gonna be to make sure that we restore that confidence“ (CBS News, 16. November 2008, Obama On Economic Crisis, Transition; http://www.cbsnews.com/stories/2008/11/16/60minutes/main4607893.shtml; Stand: 16. April 2009).