Ammonia : this is not the end but rather the end of the beginning

Hepatic encephalopathy (HE) represents a wide spectrum of neurological or neuropsychological symptoms caused by liver disease and/or portosystemic shunts. The major role of hyperammonemia in association with systemic inflammation and oxidative stress in the pathogenesis of HE has progressively emerged. However, the cascading downstream effects caused by these pathogenic factors remain unresolved. The underlying abnormalities which are thought to cause HE include modification of glutamatergic and GABAergic neurotransmission, mitochondrial dysfunction, energy impairment, lactate dyshomeostasis, increased blood-brain barrier permeability, brain edema/astrocyte swelling, as well as accumulation of toxic compounds (manganese, bile acids, indols)

Variable density sampling based on physically plausible gradient waveform. Application to 3D MRI angiography

Performing k-space variable density sampling is a popular way of reducing scanning time in Magnetic Resonance Imaging (MRI). Unfortunately, given a sampling trajectory, it is not clear how to traverse it using gradient waveforms. In this paper, we actually show that existing methods [1, 2] can yield large traversal time if the trajectory contains high curvature areas. Therefore, we consider here a new method for gradient waveform design which is based on the projection of unrealistic initial trajectory onto the set of hardware constraints. Next, we show on realistic simulations that this algorithm allows implementing variable density trajectories resulting from the piecewise linear solution of the Travelling Salesman Problem in a reasonable time. Finally, we demonstrate the application of this approach to 2D MRI reconstruction and 3D angiography in the mouse brain.Comment: IEEE International Symposium on Biomedical Imaging (ISBI), Apr 2015, New-York, United State

Complexity of equal 0-surgeries

We say that two knots are friends if they share the same 0-surgery. Two friends with different sliceness status would provide a counterexample to the 4-dimensional smooth Poincar\'e conjecture. Here we create a census of all friends with small crossing numbers c and tetrahedral complexities t, and compute their smooth 4-genera. In particular, we compute the minimum of c(K)+c(K') and of t(K)+t(K') among all friends K and K'. Along the way, we classify all 0-surgeries of knots of at most 15 crossings.Comment: 13 pages, 1 figure, 5 Table

Anti-avoidance jurisprudence in direct taxation: the CJEU between politics and certainty

Over a span of several years, the Court of Justice of the European Union (CJEU) developed a framework for anti-abuse in the context of European law and particularly established criteria for justifying restrictions on the fundamental freedoms in the tax context. In tax cases on anti-avoidance that are more recent, however, the court has demonstrated a notable change in its stance towards this issue that represents a disruption in the consistent development of its jurisprudence on abuse. While the court covers the contradictions in its case law by passing an impression of continuity between disparate decisions, it is remarkable how recent rulings draw from Organisation for Economic Co-operation and Development (OECD) language. This reliance on concepts from a non-EU institution, however, leads to legitimacy concerns. The increasing importance of international organizations and public opinion – for example, in reaction to the Panama Papers – in shaping the international tax landscape is undeniable. While high-profile projects like Base Erosion and Profit Shifting (BEPS) and Global Anti-Base Erosion (GloBE) highlight international tax issues, they also exert political pressure on judicial bodies such as the CJEU which leads to less methodological decisions that will align the court with political interests. In this context, the CJEU’s acting as a political player at the borderline of its competences is to be viewed critically, especially regarding the recent shift in its case law on abuse and tax avoidance that leads to concerns over legal certainty

From variable density sampling to continuous sampling using Markov chains

International audienceSince its discovery over the last decade, Compressed Sensing (CS) has been successfully applied to Magnetic Resonance Imaging (MRI). It has been shown to be a powerful way to reduce scanning time without sacrificing image quality. MR images are actually strongly compressible in a wavelet basis, the latter being largely incoherent with the k-space or spatial Fourier domain where acquisition is performed. Nevertheless, since its first application to MRI [1], the theoretical justification of actual k-space sampling strategies is questionable. Indeed, the vast majority of k-space sampling distributions have been heuris- tically designed (e.g., variable density) or driven by experimental feasibility considerations (e.g., random radial or spiral sampling to achieve smoothness k-space trajectory). In this paper, we try to reconcile very recent CS results with the MRI specificities (magnetic field gradients) by enforcing the measurements, i.e. samples of k-space, to fit continuous trajectories. To this end, we propose random walk continuous sampling based on Markov chains and we compare the reconstruction quality of this scheme to the state-of-the art

A rapid and low noise switch from RANS to WMLES on curvilinear grids with compressible flow solvers

International audienceA turbulent inflow for a rapid and low noise switch from RANS to Wall-Modelled LES on curvilinear grids with compressible flow solvers is presented. It can be embedded within the computational domain in practical applications with WMLES grids around three-dimensional geometries in a flexible zonal hybrid RANS/LES modelling context. It relies on a physics-motivated combination of Zonal Detached Eddy Simulation (ZDES) as the WMLES technique together with a Dynamic Forcing method processing the fluctuations caused by a Zonal Immersed Boundary Condition describing roughness elements. The performance in generating a physically-sound turbulent flow field with the proper mean skin friction and turbulent profiles after a short relaxation length is equivalent to more common inflow methods thanks to the generation of large-scale streamwise vorticity by the roughness elements. Comparisons in a low Mach-number zeropressure-gradient flat-plate turbulent boundary layer up to Reθ = 6 100 reveal that the pressure field is dominated by the spurious noise caused by the synthetic turbulence methods (Synthetic Eddy Method and White Noise injection), contrary to the new low-noise approach which may be used to obtain the low-frequency component of wall pressure and reproduce its intermittent nature. The robustness of the method is tested in the flow around a three-element airfoil with WMLES in the upper boundary layer near the trailing edge of the main element. In spite of the very short relaxation distance allowed, self-sustainable resolved turbulence is generated in the outer layer with significantly less spurious noise than with the approach involving White Noise. The ZDES grid count for this latter test case is more than two orders of magnitude lower than the Wall-Resolved LES requirement and a unique mesh is involved, which is much simpler than some multiple-mesh strategies devised for WMLES or turbulent inflow

A projection method on measures sets

We consider the problem of projecting a probability measure π on a set MN of Radon measures. The projection is defined as a solution of the following variational problem: inf µ∈M N h (µ − π) 2 2 , where h ∈ L 2 (Ω) is a kernel, Ω ⊂ R d and denotes the convolution operator. To motivate and illustrate our study, we show that this problem arises naturally in various practical image rendering problems such as stippling (representing an image with N dots) or continuous line drawing (representing an image with a continuous line). We provide a necessary and sufficient condition on the sequence (MN) N ∈N that ensures weak convergence of the projections (µ * N) N ∈N to π. We then provide a numerical algorithm to solve a discretized version of the problem and show several illustrations related to computer-assisted synthesis of artistic paintings/drawings