Applications of hydrodynamic models for modeling drifting jellyfish blooms around the Maltese Islands

Within the ambit of the MED-JELLYRISK project, the IOI-Malta Operational Centre is coordinating the development of a jellyfish dispersion model capable of generating both a hindcast and a forecast (extending up to a maximum of 4 days following day of sighting) output for the dispersion trajectory taken by a jellyfish bloom of specified densities and sighted at a specified location. The numerical tool is based on a high resolution hydrodynamic finite element coastal ocean model (SHYFEM) coupled with a particles tracking lagrangian model for reproducing both the surface water circulation and the transport and diffusion of numerical particles inside the area of interest. The coastal model is nested into an Open Ocean sub-regional 3D hydrodynamic model (ROSARIO), having a resolution of 1/640 and which reproduces daily the 3D hydrodynamic fields needed for predicting the fate of released numerical particles. The model domain was reproduced by means of a finite element mesh that was designed to accurately reproduce both the bathymetric features and the complex geometry of the Maltese archipelago coastlines. The system will be integrated into a Graphical User Interface (GUI) which will allow the user to define the position in time and space of a hypothetical bloom found in the Maltese waters, to select the amount of particles to simulate the jellyfish biomass and to launch the trajectory model run. The model will be partly validated by using the trajectories followed by a series of open water and coastal water drifters whose dispersion is geo-referenced and which have been regularly released by the IOI-MOC within Maltese coastal waters.peer-reviewe

The role of cellular fibronectin in the interaction of human endothelial cells with polymers

During in-vitro adhesion, spreading and proliferation of human endothelial cells (HEC) on tissue culture polystyrene (TCPS), cellular fibronectin is deposited onto the surface of TCPS in spite of the fact that relatively large amounts of proteins have been adsorbed from the serum-containing culture medium to this surface. Evidence is presented that serum proteins, adsorbed to the TCPS surface, are displaced by cellular fibronectin. In addition, the interaction of HEC with polyethylene, precoated with monoclonal antibodies directed against HEC membrane antigens and against extracellular matrix compounds, was studied. F(ab')2 fragments of two monoclonal antibodies were also included in this study. Preadsorption of these antibodies and F(ab')2 fragments resulted in cell adhesion and spreading as well as moderate cell proliferation (or no proliferation) for several days. A good cell proliferation of HEC was only observed on polyethylene precoated with fibronectin or an antibody directed against fibronectin. The results indicate that the direct or indirect deposition of fibronectin is a prerequisite for the proliferation of HEC. It is suggested that fibronectin, bound to a solid substrate, provides a biochemical signal necessary for the proliferation of HEC

No alternative to proliferation

We reflect on the nature, role and limits of non-empirical theory assessment in fundamental physics, focusing in particular on quantum gravity. We argue for the usefulness and, to some extent, necessity of non-empirical theory assessment, but also examine critically its dangers. We conclude that the principle of proliferation of theories is not only at the very root of theory assessment but all the more necessary when experimental tests are scarce, and also that, in the same situation, it represents the only medicine against the degeneration of scientific research programmes.Comment: 15 pages; contribution to the volume "Why trust a theory?", edited by: R. Dardashti, R. Dawid, K. Thebault, to be published by Cambridge University Pres

Skin Cell Proliferation Stimulated by Microneedles

A classical wound may be defined as a disruption of tissue integrity. Wounds, caused by trauma from accidents or surgery, that close via secondary intention rely on the biological phases of healing, i.e., hemostasis, inflammation, proliferation, and remodeling (HIPR). Depending on the wound type and severity, the inflammation phase begins immediately after injury and may last for an average of 7–14 days. Concurrent with the inflammation phase or slightly delayed, cell proliferation is stimulated followed by the activation of the remodeling (maturation) phase. The latter phase can last as long as 1 year or more, and the final healed state is represented by a scar tissue, a cross-linked collagen formation that usually aligns collagen fibers in a single direction. One may assume that skin microneedling that involves the use of dozens or as many as 200 needles that limit penetration to 1.5 mm over 1 cm2 of skin would cause trauma and bleeding followed by the classical HIPR. However, this is not the case or at least the HIPR phases are significantly curtailed and healing never ends in a scar formation. Conversely dermabrasion used in aesthetic medicine for improving skin quality is based on “ablation” (destruction or wounding of superficial skin layers), which requires several weeks for healing that involves formation of new skin layers. Such procedures provoke an acute inflammatory response. We believe that a less intense inflammatory response occurs following microneedle perforation of the skin. However, the mechanism of action of microneedling appears to be different. Here we review the potential mechanisms by which microneedling of the skin facilitates skin repair without scarring after the treatment of superficial burns, acne, hyperpigmentation, and the non-advancing periwound skin surrounding the chronic ulcerations of the integument