A Mathematical Model of Liver Cell Aggregation In Vitro

The behavior of mammalian cells within three-dimensional structures is an area of intense biological research and underpins the efforts of tissue engineers to regenerate human tissues for clinical applications. In the particular case of hepatocytes (liver cells), the formation of spheroidal multicellular aggregates has been shown to improve cell viability and functionality compared to traditional monolayer culture techniques. We propose a simple mathematical model for the early stages of this aggregation process, when cell clusters form on the surface of the extracellular matrix (ECM) layer on which they are seeded. We focus on interactions between the cells and the viscoelastic ECM substrate. Governing equations for the cells, culture medium, and ECM are derived using the principles of mass and momentum balance. The model is then reduced to a system of four partial differential equations, which are investigated analytically and numerically. The model predicts that provided cells are seeded at a suitable density, aggregates with clearly defined boundaries and a spatially uniform cell density on the interior will form. While the mechanical properties of the ECM do not appear to have a significant effect, strong cell-ECM interactions can inhibit, or possibly prevent, the formation of aggregates. The paper concludes with a discussion of our key findings and suggestions for future work

Post-apartheid transition in a small South African town: interracial property transfer in Margate, KwaZulu-Natal

Post-apartheid transition in South Africa's small towns has received little attention. Using the South African Property Transfer Guide, 2500 residential transfers were analysed in Margate. Spatial and temporal patterns in Black house purchase were interpreted through discussions with key actors. The findings indicate the importance of micro-dynamics in determining specific post-apartheid transitions and confirm the relationship between racial employment profiles and housing markets. Black in-movement to previously White areas has focused on Extension 3, where private building of low-cost housing has occurred, but the area is now becoming resegregated. Whilst peripheral housing need not imply exclusion from services in small towns, unpaid mortgage bills and municipal rates have led to repossessions and affected the credit status of new Black buyers. <br/

Do radio stations in New Zealand target successfully?

While segmentation by the majority of marketers is seen as a key strategic activity, the results of this research are consistent with prior studies that raise question as to the success of the ability of companies to implement segmentation strategies successfully