Analytical and Numerical Estimates for Solar Radiation Pressure Semi-secular Resonances

The aim of this work is to provide new insights on the dynamics associated to the resonances which arise as a consequence of the coupling of the effect due to the oblateness of the Earth and the Solar Radiation Pressure (SRP) effect for an uncontrolled object with moderate to high area-to-mass ratio. Analytical estimates for the location of the resulting resonant equilibrium points are provided, together with formulas to compute the maximum amplitude of the corresponding variation in the eccentricity, as a function of the initial conditions of the object and of its area-to-mass ratio. The period of the variations of the eccentricity and inclinations due to such resonances is estimated using classical formulas. A classification based on the strength of the SRP resonances is provided. The estimates presented in the paper are validated using numerical tools, including the use of Fast Lyapunov Indicators to draw phase portraits and bifurcation diagrams. Many FLI maps depicting the location and overlapping of SRP resonances are presented. The results from this paper suggest that SRP resonances could be modeled in the context of either the Extended Fundamental Model by [1] or the Second Fundamental Model by [2]. [1] S. Breiter. Extended fundamental model of resonance. Celestial Mechanics and Dynamical Astronomy, 85:209-218, 03 (2003). doi: 10.1023/A:1022569419866 [2] J. Henrard and A. Lemaitre. A second fundamental model for resonance. Celestial Mechanics, 30:197-218, (1983). doi: 10.1007/BF01234306Comment: 42 pages, 32 figure

Mimicking the kidney: A key role in organ-on-chip development

Pharmaceutical drug screening and research into diseases call for significant improvement in the effectiveness of current in vitro models. Better models would reduce the likelihood of costly failures at later drug development stages, while limiting or possibly even avoiding the use of animal models. In this regard, promising advances have recently been made by the so-called "organ-on-chip"(OOC) technology. By combining cell culture with microfluidics, biomedical researchers have started to develop microengineered models of the functional units of human organs. With the capacity to mimic physiological microenvironments and vascular perfusion, OOC devices allow the reproduction of tissue- and organ-level functions. When considering drug testing, nephrotoxicity is a major cause of attrition during pre-clinical, clinical, and post-approval stages. Renal toxicity accounts for 19% of total dropouts during phase III drug evaluation more than half the drugs abandoned because of safety concerns. Mimicking the functional unit of the kidney, namely the nephron, is therefore a crucial objective. Here we provide an extensive review of the studies focused on the development of a nephron-on-chip device

PBZ*-Lattices: Structure Theory and Subvarieties

We investigate the structure theory of the variety of \emph{PBZ*-lattices} and some of its proper subvarieties. These lattices with additional structure originate in the foundations of quantum mechanics and can be viewed as a common generalisation of orthomodular lattices and Kleene algebras expanded by an extra unary operation. We lay down the basics of the theories of ideals and of central elements in PBZ*-lattices, we prove some structure theorems, and we explore some connections with the theories of subtractive and binary discriminator varieties.Comment: 29 page