Arbitrage and deflators in illiquid markets

This paper presents a stochastic model for discrete-time trading in financial markets where trading costs are given by convex cost functions and portfolios are constrained by convex sets. The model does not assume the existence of a cash account/numeraire. In addition to classical frictionless markets and markets with transaction costs or bid-ask spreads, our framework covers markets with nonlinear illiquidity effects for large instantaneous trades. In the presence of nonlinearities, the classical notion of arbitrage turns out to have two equally meaningful generalizations, a marginal and a scalable one. We study their relations to state price deflators by analyzing two auxiliary market models describing the local and global behavior of the cost functions and constraints

Giant rotary power of a fishnet-like metamaterial

We show experimentally and numerically that cholesteric-type metal-dielectric structures, made of twisted sub-wavelength hole elliptical–shaped arrays, exhibit strong optical activity and circular dichroism. The experimental demonstration is carried out with terahertz time-domain spectroscopy measurements on a three layered structure operating around 0.5 THz, leading to a rotary power as high as 1000◦/wavelength. The contribution of the chirality factor (κ), permittivity (ε), and permeability (μ) is discussed after the retrieval of effective parameters from the complex scattering one

The use of ERT to identity irrigatation patterns and efficiency in potato fields

Potatoes often need irrigation during dry summer weeks, because of their shallow root system, high water needs, and drought sensitivity. Lack of water at crucial moments can result in low tuber yield and loss of tuber quality. Farmers typically adopt a ridge-furrow plant system in which the fate of rain and irrigation water is not well known. As the incoming water is partitioned by plant leaves and by the microtopography itself, the boundary conditions for hydrological modelling (i.e. spatial distribution of incoming water fluxes) for agricultural decision-making are uncertain. There is a need to develop a better understanding of water and nutrient fluxes, especially under irrigated conditions. Non-invasive imaging techniques, such as electrical resistivity tomography (ERT) are increasingly used in the agricultural context to characterize soil moisture dynamics. Nevertheless, non-uniqueness of the inversion, and errors induced by uncertainties related to the measurement process, still weigh on the application of ERT to high-resolution agricultural problems. In this paper, we explore the artefacts we can expect originating from uncertainties during the ERT measurement process using a virtual experiment. We then show the results of a monitoring experiment performed in a potato field in 2018. Although some artefacts are to be expected from microtopography uncertainty in potato ridge-furrow systems, timelapse ERT monitoring remains a valuable tool to reveal infiltration and soil redistribution patterns after irrigation events. As inversion artefacts due to microtopography uncertainty typically occur in places where we also expect to see rapid soil moisture changes, due to root water uptake, an assessment of the changes of microtopography over the course of the experiment is required to reach reliable and quantitative tomograms. Nevertheless, ERT is a very promising tool to better understand spatio-temporal water dynamics in irrigated potato furrow-ridge plant systems, especially when looking at time-lapse differences during infiltration or water uptake processes and in cases of minor to moderate erosion of the ridges

Sauvegarde du patrimoine en cas de sinistre : conception d'une solution de localisation et de surveillance a base de RFIDs actifs, défis et perspectives. 2ème Atelier sur la Gestion des Données dans les Systèmes d'Information Pervasifs

International audience. La protection contre les incendies constitue l?une des pierres angulaires de la politique de sauvegarde du patrimoine menée par les musées et monuments historiques. Face à ce besoin, nous établissons les défis à relever, nos perspectives de recherche et les prémisses d?un système de surveillance d?une intervention suite à un incendie dans un musée. En munissant les oeuvres d?art d?étiquettes RFID et les combattants du feu de lecteurs RFID, notre objectif est de localiser dynamiquement les ?uvres devant être mises à l?abr

opesci/devito: Devito-3.4

Release notes Preliminary support for MPI (no changes to user code requested) Support for staggered grids Improved compilation technology Improved Operator autotuning More powerful DSL (e.g., take derivatives of entire expressions such as (u+v).dx) More efficient pickling Misc bug fixes New modeling examples based on the elastic wave equation New examples describing aspects of the compilation technologyRelease notes Preliminary support for MPI (no changes to user code requested) Support for staggered grids Improved compilation technology Improved Operator autotuning More powerful DSL (e.g., take derivatives of entire expressions such as (u+v).dx) More efficient pickling Misc bug fixes New modeling examples based on the elastic wave equation New examples describing aspects of the compilation technology3.

3D Photonic Crystals based on epitaxial III-V semiconductor structures for nonlinear optical interactions

International audienceWe have investigated a three-dimensionally periodic (3D) photonic crystal structure based on an epitaxial periodic GaAs/Al0.93Ga0.07As multilayer structure that was designed for non-linear optical interactions. The 3D photonic crystal structure consisted of a two-dimensionally periodic planar photonic crystal hole pattern etched into the one-dimensionally periodic multilayer structure designed for a centre wavelength of lambda = 1.6 µm. Numerical simulations on the 3D PhC structure have shown that it should exhibit slow group velocity modal features near the edge of the photonic bandgap