A Cellular Potts Model simulating cell migration on and in matrix environments

Cell migration on and through extracellular matrix plays a critical role in a wide variety of physiological and pathological phenomena, and in scaffold-based tissue engineering. Migration is regulated by a number of extracellular matrix- or cell-derived biophysical parameters, such as matrix fiber orientation, gap size, and elasticity, or cell deformation, proteolysis, and adhesion. We here present an extended Cellular Potts Model (CPM) able to qualitatively and quantitatively describe cell migratory phenotype on both two-dimensional substrates and within three-dimensional environments, in a close comparison with experimental evidence. As distinct features of our approach, the cells are represented by compartmentalized discrete objects, differentiated in the nucleus and in the cytosolic region, while the extracellular matrix is composed of a fibrous mesh and of a homogeneous fluid. Our model provides a strong correlation of the directionality of migration with the topological ECM distribution and, further, a biphasic dependence of migration on the matrix density, and in part adhesion, in both two-dimensional and three-dimensional settings. Moreover, we demonstrate that the directional component of cell movement is strongly correlated with the topological distribution of the ECM fibrous network. In the three-dimensional networks, we also investigate the effects of the matrix mechanical microstructure, observing that, at a given distribution of fibers, cell motility has a subtle bimodal relation with the elasticity of the scaffold. Finally, cell locomotion requires deformation of the cell's nucleus and/or cell-derived proteolysis of steric fibrillar obstacles within rather rigid matrices characterized by small pores, not, however, for sufficiently large pores. In conclusion, we here propose a mathematical modeling approach that serves to characterize cell migration as a biological phenomen in health, disease and tissue engineering applications. The research that led to the present paper was partially supported by a grant of the group GNFM of INdA

Food Safety in China: The Structure and Substantive Foci of an Emerging Field of Social Science Research

This paper is the first to describe the structure and content of the English language social science literature on food safety in China. To do this research we systematically searched Web of Science and Scopus, the most comprehensive indexes, using the terms “Food Safety” AND “China” OR “Chinese”. To focus our search results, we used the index features available on Web of Science and Scopus, and limited results to the English language, peer-reviewed journal articles, social sciences, and published in the period of 2009 to 2015. This resulted in 272 selected journal articles, with a final data set of 185 articles for review. A food safety system model we developed was used to classify and present the findings derived from content analysis of abstracts, titles, and keywords. Our findings show that the research reviewed is unevenly distributed across the components of the food safety system model. The greatest proportions of the literature reviewed focused on consumers, primary and secondary producers and products, and government legislators and regulators, respectively. Smaller proportions focused on food wholesalers, retailers, researchers, educators, and the media. Few of the articles reviewed used a model of the food safety system. None identified an explicit knowledge transfer strategy

The Easyline+ Project: Evaluation of a User Interface Developed to Enhance Independent Living of Elderly and Disabled people

This paper reports the usability evaluation of interfaces developed to enable elderly and disabled people interact remotely with kitchen appliances in the home to enhance their independent living. A number of evaluation exercises were undertaken throughout the project’s development, including user-participative workshops and focus groups. This paper focuses on the summative usability evaluation exercise, which comprised a laboratory-based study in a simulated home environment, with a view to determining the appropriateness of employing this approach with potentially vulnerable participants. The study involved 27 participants interacting with the user interface. Their behaviour was observed and recorded, and their interaction with the system was analysed. They were also given a post-session questionnaire, where their opinions of the usability of the interface were solicited. The results of the usability testing were positive, and insight has been gained into how products of this nature can be further improved. The experience of conducting laboratory-based studies with vulnerable users was positive and led to propose in this paper a set of guidelines for future work in evaluating usability for work in this domain