Cell migration codes

Fig. 2.2D-DIAS generated stacked perimeter plots (a) and difference pictures (b-d) of three wild-type Dictyostelium cells migrating in buffer. Perimeter outiines in (a) are stacked at 8-s intervals for a total of f 0 min. The last image in the series is fiiied with gray. Arrows show direction of travel and turning. Difference pictures in (b-d) are overlayed at 8-s intervals. Expansion zones are coded dark gray, retraction zones are hatched, and common zones are light gray. These images are used to evaluate behaviors such as turning and pseudopod dynamics.

In contrast to the pseudo 3-D models, tmly multi-dimensional models use, in general, finite element or finite volume CFD (Computational Fluid Dynamics) techniques to solve full 3-D Navier-Stokes equations with appropriate modifications to account for electrochemistry and current distribution. The details of electrochemistry may vary from code to code, but the current density is calculated almost exclusively from Laplace equation for the electric potential (see Equation (5.24)). Inside the electrolyte, the same equation represents the migration of ions (e g. 0= in SOFC), elsewhere it represents the electron/charge transfer. In what follows, we briefly summarize a commonly used multi-dimensional model for PEM fuel cells because of its completeness and of the fact that it also addresses most essential features of SOFC modeling. 

How a DNA vaccine might work. A viral gene coding for a core or capsid protein is inserted into a plasmid. The plasmids are injected into cells where the plasmid migrates to the nucleus. Viral proteins are expressed in the cells producing both a cell-mediated and humoral immune response. (Reproduced with permission from W. M. McDonnel and F. K. Ashari, DNA vaccines, N. Engl. J. Med. 314,44 (1996)]. 

When the governing model is given by the convection-diffusion equation (no electrical migration effects are considered), well-established numerical methods can be used directly in electrochemical cell design. When using commercial software, it should be remembered that the code has probably been benchmarked for applications different from those found in metallization, where spatial distributions of flux at high Schmidt numbers may be of more interest than the spatial average flux. Freitas has recently provided a comparison of several commercial CFD codes. Many of these codes are based on a finite-volume method (FVM) or a finite-element method. West jj yg discussed the application of... 

Once thyroid hormone enters a cell, it binds temporarily with a spt plasmic protein. Thyroid hormone molecules migrate to the nucleus chondria, where they bind to receptors. In the nucleus the binding hormone initiates the transcription of genes that play crucial roles i of cellular processes, such as those that code for growth hormone a ATPase. In mitochondria, thyroid hormones promote oxygen consur increased fatty acid oxidation. (The mechanism by which this latter pro< is not understood.)... 

Figure 4 Depiction of cell tracks in Imaris using a time-based color code (A and B) in original movie, after processing as described in Section 8 step 2 (C and D) after defining a common starting point (white dot). Dotted line indicates y-axis atx=0. Images show highly directional migration for wild type In contrast to Ccr7-deficlent bone marrow-derived dendritic cells. Scale bar 100 pm.

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