1,857 research outputs found
Altered Narratives: Female Eighteenth-Century French Authors Reinterpreted
Vol. I of the Eighteenth-Century French World Centre-The University of Western Ontario, edited by Servanne Woodward, Anthony Purdy, Minnette Gaudet, and Peter R. SaĂŹzhttps://ir.lib.uwo.ca/frenchebooks/1000/thumbnail.jp
Development of non-linear guidance algorithms for asteroids close-proximity operations
In this paper, we discuss non-linear methodologies that can be employed to devise real-time algorithms suitable for guidance and control of spacecrafts during asteroid close-proximity operations. Combination of optimal and sliding control theory provide the theoretical framework for the development of guidance laws that generates thrust commands as function of the estimated spacecraft state. Using a Lyapunov second theorem one can design non-linear guidance laws that are proven to be globally stable against unknown perturbations with known upper bound. Such algorithms can be employed for autonomous targeting of points of the asteroid surface (soft landing , Touch-And-Go (TAG) maneuvers). Here, we theoretically derived and tested the Optimal Sliding Guidance (OSG) for close-proximity operations. The guidance algorithm has its root in the generalized ZEM/ZEV feedback guidance and its mathematical equations are naturally derived by a proper definition of a sliding surface as function of Zero-Effort-Miss and Zero-Effort-Velocity. Thus, the sliding surface allows a natural augmentation of the energy-optimalguidance via a sliding mode that ensures global stability for the proposed algorithm. A set of Monte Carlo simulations in realistic environment are executed to assess the guidance performance in typical operational scenarios found during asteroids close-proximity operations. OSG is shown to satisfy stringent requirements for asteroid pinpoint landing and sampling accuracy
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Cell-to-cell variability in cell death: can systems biology help us make sense of it all?
One of the most common observations in cell death assays is that not all cells die at the same time, or at the same treatment dose. Here, using the perspective of the systems biology of apoptosis and the context of cancer treatment, we discuss possible sources of this cell-to-cell variability as well as its implications for quantitative measurements and computational models of cell death. Many different factors, both within and outside of the apoptosis signaling networks, have been correlated with the variable responses to various death-inducing treatments. Systems biology models offer us the opportunity to take a more synoptic view of the cell death process to identify multifactorial determinants of the cell death decision. Finally, with an eye toward âsystems pharmacology', we discuss how leveraging this new understanding should help us develop combination treatment strategies to compel cancer cells toward apoptosis by manipulating either the biochemical state of cancer cells or the dynamics of signal transduction
Wheat stripe rust disease dynamics in southern Alberta, Saskatchewan, and Manitoba, 2009-2014
Non-Peer Reviewe
Characterization of Structural and Electronic Transitions During Reduction and Oxidation of Ru(acac)3 Flow Battery Electrolytes by using Xâray Absorption Spectroscopy
Metal acetylacetonates possess several very attractive electrochemical properties; however, their cyclabilities fall short of targets for use in nonaqueous redox flow batteries. This paper describes structural and compositional changes during the reduction and oxidation of ruthenium(III) acetylacetonate [Ru(acac)3], a representative acetylacetonate. Voltammetry, bulk electrolysis, and inâ
situ Xâray absorption spectroscopy (XAS) results are complemented by those from density functional theory (DFT) calculations. The reduction of Ru(acac)3 in acetonitrile is highly reversible, producing a couple at â1.1â
V versus Ag/Ag+. Inâ
situ XAS and DFT indicate the formation of [Ru(acac)3]â with RuâO bonds lengthened relative to Ru(acac)3, nearly all of the charge localized on Ru, and no ligand shedding. The oxidation of Ru(acac)3 is quasireversible, with a couple at 0.7â
V. The initial product is likely [Ru(acac)3]+; however, this species is shortâlived, converting to a product with a couple at â0.2â
V, a structure that is nearly identical to that of Ru(acac)3 within 3â
Ă
of Ru, and approximately 70â% of the charge extracted from Ru (balance from acetylacetone). This nonâinnocence likely contributes to the instability of [Ru(acac)3]+. Taken together, the results suggest that the stabilities and cyclabilities of acetylacetonates are determined by the degree of charge transfer to/from the metal.Track changes: The structural and electronic changes of Ru(acac)3 during oxidation and reduction are characterized using bulk electrolysis and inâ
situ Xâray absorption spectroscopy. Reduction is found to be reversible with minimal structural changes, and the electrons being stored entirely on the ruthenium. Oxidation results in a rapid side reaction as a result of electrons extracted from the ligand.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134821/1/celc201600360-sup-0001-misc_information.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134821/2/celc201600360_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134821/3/celc201600360.pd
The 2011 stripe rust epidemic in western Canada
Non-Peer Reviewe
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