Simulation of Acoustic Wave Propagation in Anisotropic Media Using Dynamic Programming Technique

International audienceIt is known that the Hamiltonian of the eikonal equation for an anisotropic medium may be nonconvex, which excludes the application of Fermat’s minimum-time principle related to minimum-time control problems. The idea proposed in this paper consists in finding a conflict control problem (differential game) whose Hamiltonian coincides with the Hamiltonian of the eikonal equation. It turns out that this is always possible due to Krasovskii’s unification technique. Having such a differential game allows us to apply dynamic programming methods to computing the value function of the game, and therefore to describe the propagation of wave fronts. This method is very appropriate for the simulation of wave patterns in surface acoustic wave biosensors. Numerical computations given in this paper prove the feasibility of the approach proposed

Broad-spectrum antivirals against viral fusion

© 2015 Macmillan Publishers LimitedEffective antivirals have been developed against specific viruses, such as HIV, Hepatitis C virus and influenza virus. This ‘one bug–one drug’ approach to antiviral drug development can be successful, but it may be inadequate for responding to an increasing diversity of viruses that cause significant diseases in humans. The majority of viral pathogens that cause emerging and re emerging infectious diseases are membrane-enveloped viruses, which require the fusion of viral and cell membranes for virus entry. Therefore, antivirals that target the membrane fusion process represent new paradigms for broad-spectrum antiviral discovery. In this Review, we discuss the mechanisms responsible for the fusion between virus and cell membranes and explore how broad-spectrum antivirals target this process to prevent virus entryWork on broad-spectrum antivirals against fusion was supported by US National Institutes of Health (NIH) grants U01 AI070495 and U01 AI082100, and by a project grant from the Pacific Southwest Regional Center of Excellence for Biodefense and Emerging Infectious Disease (U54 AI065359) (to B.L.). Work on the effect of photosensitization on biomembranes was supported by the Portuguese Fundação para a Ciência e Tecnologia – Ministério da Educação e Ciência (FCT-MEC) project VIH/SAU/0047/2011 (to N.C.S.)