Parallel Linear Multigrid Algorithms Applied to the Acceleration of Compressible Flows

The interest in unstructured meshes for Computational Fluid Dynamics (CFD) applications appears to be increansingly important in the industrial community. Industrial applications require the numerical simulation of complex flows (i.e. the underlying flows exhibit localized high variations of physical quantities) around or within complex geometries. Unstructured meshes are particularly well suited to these kinds of simulation due to their ability in accurately discretizing complex computational domains and, to their flexibility in dynamically refining and derefining, or deforming, in order to match the underlying flow features. Concerning flow solvers, the main question appears to be the lack of efficiency demonstrated by unstructured mesh solvers compared to structured ones. Many efficient methods developed in the structured context are not easily extensible to unstructured meshes and much research work has yet to be done in this direction. During the last ten years, several such works have demonstrated that multigrid principles can yield robust and efficient unstructured mesh solvers (see for example Lallemand {\it et al.}\cite{Lal92}, Koobus {\it et al.}\cite{Lal94}, Carré\cite{Car97}, Mavriplis {\it et al.}\cite{Mav87}-\cite{Mav88}-\cite{Mav95}). In this report, we describe ongoing research activities aiming at the construction of efficient and robust unstructured multigrid solvers for complex 2D and 3D flow simulations. Both academic and industrial aspects are considered

Semiring and semimodule issues in MV-algebras

In this paper we propose a semiring-theoretic approach to MV-algebras based on the connection between such algebras and idempotent semirings - such an approach naturally imposing the introduction and study of a suitable corresponding class of semimodules, called MV-semimodules. We present several results addressed toward a semiring theory for MV-algebras. In particular we show a representation of MV-algebras as a subsemiring of the endomorphism semiring of a semilattice, the construction of the Grothendieck group of a semiring and its functorial nature, and the effect of Mundici categorical equivalence between MV-algebras and lattice-ordered Abelian groups with a distinguished strong order unit upon the relationship between MV-semimodules and semimodules over idempotent semifields.Comment: This version contains some corrections to some results at the end of Section

Asymptotics of Selberg-like integrals: The unitary case and Newton's interpolation formula

We investigate the asymptotic behavior of the Selberg-like integral $$\frac1{N!}\int_{[0,1]^N}x_1^p\prod_{i<j}(x_i-x_j)^2\prod_ix_i^{a-1}(1-x_i)^{b-1}dx_i$$, as $N\to\infty$ for different scalings of the parameters $a$ and $b$ with $N$. Integrals of this type arise in the random matrix theory of electronic scattering in chaotic cavities supporting $N$ channels in the two attached leads. Making use of Newton's interpolation formula, we show that an asymptotic limit exists and we compute it explicitly

Redox-Driven Transformation of a Discrete Molecular Cage into an Infinite 3D Coordination Polymer

Two M12L6 redox‐active self‐assembled cages constructed from an electron‐rich ligand based on the extended tetrathiafulvalene framework (exTTF) and metal complexes with a linear geometry (PdII and AgI) are depicted. Remarkably, based on a combination of specific structural and electronic features, the polycationic self‐assembled AgI coordination cage undergoes a supramolecular transformation upon oxidation into a three‐dimensional coordination polymer, that is characterized by X‐ray crystallography. This redox‐controlled change of the molecular organization results from the drastic conformational modifications accompanying oxidation of the exTTF moiety

Bronchial responses to substance P after antigen challenge in the guinea-pig: in vivo and in vitro studies

The effect of antigen challenge on the airway responses to substance P and on the epithelial neutral endopeptidase (NEP) activity was investigated in aerosol sensitized guinea-pigs. In vivo, bronchial responses to aerosolized substance P were similar to the responses observed in antigen-challenged guinea-pigs and in the control groups. In contrast, when the guinea-pigs were pretreated with the NEP inhibitor, phosphoramidon, a significant increase in the airway responses to substance P was observed after antigen challenge in vivo. However, in vitro, the contractile responses of the tracheal smooth muscle to substance P were similar between groups of guinea-pigs, in respect to the presence or absence of the epithelium and/or phosphoramidon. Histological studies showed an accumulation of eosinophils in the tracheal submucosa after antigen challenge and intact epithelial cells. These results show that in vivo bronchial hyperresponsiveness to substance P after antigen challenge in the guinea-pig is not associated with increased responses of the smooth muscle to exogenous SP in vitro. In addition, the results with phosphoramidon suggest that loss of NEP activity cannot account for the in vivo bronchial hyperresponsiveness to substance P presently observed

Controlling the Host-Guest Interaction Mode through a Redox Stimulus

A proof-of-concept related to the redox-control of the binding/releasing process in a host-guest system is achieved by designing a neutral and robust Pt-based redox-active metallacage involving two extended-tetrathiafulvalene (exTTF) ligands. When neutral, the cage is able to bind a planar polyaromatic guest (coronene). Remarkably, the chemical or electrochemical oxidation of the host-guest complex leads to the reversible expulsion of the guest outside the cavity, which is assigned to a drastic change of the host-guest interaction mode, illustrating the key role of counteranions along the exchange process. The reversible process is supported by various experimental data (1 H NMR spectroscopy, ESI-FTICR, and spectroelectrochemistry) as well as by in-depth theoretical calculations performed at the density functional theory (DFT) level

Boot-insole effects on comfort and plantar loading at the heel and fifth metatarsal during running and turning in soccer

Plantar loading may influence comfort, performance and injury risk in soccer boots. This study investigated the effect of cleat configuration and insole cushioning levels on perception of comfort and in-shoe plantar pressures at the heel and fifth metatarsal head region. Nine soccer academy players (age 15.7 ± 1.6 years; height 1.80 ± 0.40 m; body mass 71.9 ± 6.1 kg) took part in the study. Two boot models (8 and 6 cleats) and two insoles (Poron and Poron/gel) provided four footwear combinations assessed using pressure insoles during running and 180° turning. Mechanical and comfort perception tests differentiated boot and insole conditions. During biomechanical testing, the Poron insole generally provided lower peak pressures than the Poron/gel insole, particularly during the braking step of the turn. The boot model did not independently influence peak pressures at the fifth metatarsal, and had minimal influence on heel loads. Specific boot-insole combinations performed differently (P < 0.05). The 8-cleat boot and the Poron insole performed best biomechanically and perceptually, but the combined condition did not. Inclusion of kinematic data and improved control of the turning technique are recommended to strengthen future research. The mechanical, perception and biomechanical results highlight the need for a multi-faceted approach in the assessment of footwear

Ancient agriculture in Southeast Arabia: A three thousand year record of runoff farming from central Oman (Rustaq)

Runoff farming is a key hydro-agricultural strategy that has proven efficient in arid areas. Research in Arabia on the function, development, maintenance, durability and abandonment of this technology is scarce. A multiproxy investigation (cartography, sedimentology, pedology, geochemistry, paleo-ecology and chronology) was conducted on a recently abandoned terraced area in Rustaq, Northern Oman. The aim was to characterize the formation, function and management of this runoff system and the driving factors behind its success. Cycles of cultivation were identified during the Iron Age II/III periods (specifically 750–450 BCE), the Early Pre-Islamic Period (PIR) (specifically 350–200 BCE), the Early and Middle Islamic periods (specifically 8–10th C CE, 13th-14th C CE) and the late Islamic period (specifically 17th C CE and later). This expansion and perenniality was possible thanks to: 1- available water (local to micro-regional orogenic precipitation despite a regional aridification during these periods); 2- suitable soils (weathered geological outcrops, probable aeolian /dust particles); 3- a system of production combining crops and husbandry; 4- a progressive increase in agricultural specialization (crops grown and techniques) in parallel with a diversification in hydraulic technology. These results are to some degree in accordance with known phases of settlement intensification and economic growth, but also reveal the persistence of small-scale rural livelihoods during periods of harsh conditions for which archaeological traces are very scarce

Similarities and Differences in Chinese and Caucasian Adults' Use of Facial Cues for Trustworthiness Judgments

All cultural groups in the world place paramount value on interpersonal trust. Existing research suggests that although accurate judgments of another's trustworthiness require extensive interactions with the person, we often make trustworthiness judgments based on facial cues on the first encounter. However, little is known about what facial cues are used for such judgments and what the bases are on which individuals make their trustworthiness judgments.In the present study, we tested the hypothesis that individuals may use facial attractiveness cues as a “shortcut” for judging another's trustworthiness due to the lack of other more informative and in-depth information about trustworthiness. Using data-driven statistical models of 3D Caucasian faces, we compared facial cues used for judging the trustworthiness of Caucasian faces by Caucasian participants who were highly experienced with Caucasian faces, and the facial cues used by Chinese participants who were unfamiliar with Caucasian faces. We found that Chinese and Caucasian participants used similar facial cues to judge trustworthiness. Also, both Chinese and Caucasian participants used almost identical facial cues for judging trustworthiness and attractiveness.The results suggest that without opportunities to interact with another person extensively, we use the less racially specific and more universal attractiveness cues as a “shortcut” for trustworthiness judgments