11 research outputs found
Elastic interactions of active cells with soft materials
Anchorage-dependent cells collect information on the mechanical properties of
the environment through their contractile machineries and use this information
to position and orient themselves. Since the probing process is anisotropic,
cellular force patterns during active mechanosensing can be modelled as
anisotropic force contraction dipoles. Their build-up depends on the mechanical
properties of the environment, including elastic rigidity and prestrain. In a
finite sized sample, it also depends on sample geometry and boundary conditions
through image strain fields. We discuss the interactions of active cells with
an elastic environment and compare it to the case of physical force dipoles.
Despite marked differences, both cases can be described in the same theoretical
framework. We exactly solve the elastic equations for anisotropic force
contraction dipoles in different geometries (full space, halfspace and sphere)
and with different boundary conditions. These results are then used to predict
optimal position and orientation of mechanosensing cells in soft material.Comment: Revtex, 38 pages, 8 Postscript files included; revised version,
accepted for publication in Phys. Rev.
A mathematical model for simultaneous spatio-temporal dynamics of calcium and inositol 1,4,5-trisphosphate in Madin–Darby canine kidney epithelial cells
The landmark paper by Hirose et al. (Hirose, K., Kadowaki, S., Tanabe, M., Takeshima, H., Iino, M., Science 284:1527–1530, 1999) presented experimental investigations to show that not only can calcium upregulate IP3, but that it can also have an inhibitory effect on IP3. In this paper, we present a preliminary model, which is consistent with these experiments. This model includes positive and negative feedback between calcium and IP3 and is able to reproduce more precisely the data presented in Hirose et al. (Hirose, K., Kadowaki, S., Tanabe, M., Takeshima, H., Iino, M., Science 284:1527–1530, 1999). In the second part of the paper, the intracellular and intercellular calcium movement in Madin–Darby canine kidney epithelial cells is investigated. With the aid of the model we are able to identify the aspects of IP3 and calcium signalling, which should be studied further experimentally before refining the mode
El color en la arquitectura de Bruno Taut
La vinculaciĂłn del arquitecto Bruno Taut con los ideales que albergaba el movimiento para la reforma de la vida, desarrollado en la Alemania de Guillermo II como contraposiciĂłn a las consecuencias del enorme desarrollo econĂłmico e industrial, se materializĂł, esencialmente, en la proyecciĂłn de ciudades jardĂn y Siedlungen, en las que se refuerza el principio de cultura comunitaria. Esta práctica constructiva en el ámbito de la vivienda es expresiĂłn de su pensamiento social e intenta hacer efectiva la idea de una “nueva construcciĂłn” acorde con las necesidades de la sociedad moderna