Editorial overview: Membrane traffic and cell polarity

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A performance evaluation of pruning effects on hybrid neural network

In this paper, we explore the pruning effects on a hybrid mode sequential learning algorithmnamely FuzzyARTMAP-prunable Radial Basis Function (FAM-PRBF) that utilizes FuzzyARTMAP to learn a training dataset and Radial Basis Function Network (RBFN) to performregression and classification. The pruning algorithm is used to optimize the hidden layer ofthe RBFN. The experimental results show that FAM-PRBF has successfully reduced thecomplexity and computation time of the neural network.Keywords: pruning; radial basis function network; fuzzy ARTMAP

Modelling and risk analysis of the western rock lobster (Panulirus cygnus) fishery of Western Australia

The predictive power for short-term forecasting of selected biomass dynamic models was examined using the standardised catch and effort data from the 1944/45 to 1990/91 season of the western rock lobster. Risk analysis of the fishery based on the predicted fishing efforts with the Deriso-Schnute delay-difference model indicates a high probability of recruitment failure. Some hypothetical management strategies of reducing fishing effort were evaluated by taking into consideration the total catch and biological risk to the fishery

Contact inhibition of locomotion and mechanical cross-talk between cell-cell and cell-substrate adhesion determines the pattern of junctional tension in epithelial cell aggregates

We generated a computational approach to analyze the biomechanics of epithelial cell aggregates, either island or stripes or entire monolayers, that combines both vertex and contact-inhibition-of-locomotion models to include both cell-cell and cell-substrate adhesion. Examination of the distribution of cell protrusions (adhesion to the substrate) in the model predicted high order profiles of cell organization that agree with those previously seen experimentally. Cells acquired an asymmetric distribution of basal protrusions, traction forces and apical aspect ratios that decreased when moving from the edge to the island center. Our in silico analysis also showed that tension on cell-cell junctions and apical stress is not homogeneous across the island. Instead, these parameters are higher at the island center and scales up with island size, which we confirmed experimentally using laser ablation assays and immunofluorescence. Without formally being a 3-dimensional model, our approach has the minimal elements necessary to reproduce the distribution of cellular forces and mechanical crosstalk as well as distribution of principal stress in cells within epithelial cell aggregates. By making experimental testable predictions, our approach would benefit the mechanical analysis of epithelial tissues, especially when local changes in cell-cell and/or cell-substrate adhesion drive collective cell behavior.Comment: 39 pages, 8 Figures. Supplementary Information is include

Investigating the Presence of Regional Economic Growth Convergence in the Philippines using Kalman Filter

This paper investigates the presence of stochastic and dynamic convergence of the 14 regional economies in the Philippines in terms of per capita Gross Regional Domestic Product (GRDP) using regional panel data from 1988 to 2007. Stochastic convergence, which indicates convergence of regions in the long-run, is tested using Levin, Lin & Chu (LLC) and Im, Pesaran & Shin (IPS) panel unit root tests. The presence of convergence, on one hand, indicates that the economically laggard regions are gaining on the economically better-performing regions with respect to per capita GRDP. On the other hand, the lack of convergence indicates a need to reevaluate existing regional and national economic policies on development. Dynamic convergence reveals several convergence characteristics of individual regions over time. Dynamic convergence is determined by the time-varying parameter (TVP) model derived using the Kalman Filter. The paper proceeds to examine the individual convergence behavior of each region based on the value of the estimate of the parameter of the TVP. The results show that out of the 14 regions studied, seven regions are found to converge towards the average of the national per capita GDP growth rate over 1988 to 2007 while six regions lag behind the average of the national per capita GDP growth rate over the same period. No region converges towards the economic growth rate of National Capital Region, the lead region used in the study.Panel Unit Root Test, Time-varying Parameter (TVP) Model, Kalman Filter, Stochastic Convergence, Dynamic Convergence

Doing cell biology in embryos: regulated membrane traffic and its implications for cadherin biology

Regulated trafficking of cadherin adhesion molecules is often invoked as a mechanism to generate dynamic adhesive cell-cell contacts for tissue modeling and morphogenesis. The past 2-3 years have seen several important papers that tackle the cell biology of cadherin trafficking in organismal systems to provide new insights into both mechanism and morphogenetic impact