Wednesday, December 26, 2007

Math model of asymmetric distribution of cell membrane proteins 

Roland Wedlich-Söldner
To establish an asymmetric distribution of membrane proteins, diffusion has to be countered for a long enough time to allow the molecules to accumulate and fulfill their functions. This is possible through active and directed transport whose net effects need to outdo diffusion till the necessary concentration of molecules is reached.


Apart from diffusion which prevents locally elevated concentrations of molecules there are only two other cellular mechanisms that influence the distribution of membrane proteins. The already mentioned active transport processes rely on structures of the cytoskeleton to move molecules or whole organelles in specific directions. The process of endocytosis, on the other hand, allows cells to absorb membrane molecules by forming vesicles out of small portions of the cell membrane.

Topics: Cell | Biology

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Friday, December 14, 2007

Linear and non-linear learning 

Ken Carroll

The internet is changing the way we learn and that’s because of its network qualities. I believe we’ve moved beyond the Mechanical Age, and beyond the Information Age, to the Age of Networks, and therefore to the Age of Networked Learning. Networks are every where and, as Jay Cross persuasively argues, they are changing everything, including how we learn. The last time that happened we had the Enlightenment on our hands.

Topics: Learning | Web2.0 | Data2.0

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