SR120819A, an orally-active and selective neuropeptide Y Y1 receptor antagonist

AbstractAn orally-active antagonist of neuropeptide Y (NPY) Y1 receptors, SR 120819A, has been characterized. This compound displays highly selective and competitive affinity for rat, guinea-pig and human (Ki = 15 nM) NPY Y1 receptors. In vitro, SR 120819A blocks the inhibitory effect of NPY on adenylyl cyclase activity in human SK-N-MC cells and that of the selective Y1 agonist, [Leu31,Pro34]NPY, on rabbit vas deferens contraction (pA2 = 7.20 ± 0.07). In vivo, by intravenous route, this compound acts as an antagonist in anesthetized guinea-pigs and, notably, after oral administration, SR 120819A counteracts the pressor response of [Leu31,Pro34]NPY (5 μg/kg i.v.) with a long duration of action (>4 h at 5 mg/kg p.o.). Thus, SR 120819A is the first orally-effective NPY Y1 receptor antagonist yet descrobed. It could be a useful tool for exploring the role of NPY and the therapeutic relevance of an antagonist at NPY Y1 receptors

Academic team formation as evolving hypergraphs

This paper quantitatively explores the social and socio-semantic patterns of constitution of academic collaboration teams. To this end, we broadly underline two critical features of social networks of knowledge-based collaboration: first, they essentially consist of group-level interactions which call for team-centered approaches. Formally, this induces the use of hypergraphs and n-adic interactions, rather than traditional dyadic frameworks of interaction such as graphs, binding only pairs of agents. Second, we advocate the joint consideration of structural and semantic features, as collaborations are allegedly constrained by both of them. Considering these provisions, we propose a framework which principally enables us to empirically test a series of hypotheses related to academic team formation patterns. In particular, we exhibit and characterize the influence of an implicit group structure driving recurrent team formation processes. On the whole, innovative production does not appear to be correlated with more original teams, while a polarization appears between groups composed of experts only or non-experts only, altogether corresponding to collectives with a high rate of repeated interactions

French Roadmap for complex Systems 2008-2009

This second issue of the French Complex Systems Roadmap is the outcome of the Entretiens de Cargese 2008, an interdisciplinary brainstorming session organized over one week in 2008, jointly by RNSC, ISC-PIF and IXXI. It capitalizes on the first roadmap and gathers contributions of more than 70 scientists from major French institutions. The aim of this roadmap is to foster the coordination of the complex systems community on focused topics and questions, as well as to present contributions and challenges in the complex systems sciences and complexity science to the public, political and industrial spheres

Monitoring Issues in Digital Public Space - From Data Collection to Issue Mapping

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Analysis of stability and viscous-inviscid interaction in compressible boundary layers

This work belongs to the theory of fluid flows at high Reynolds number, characterised by low viscosity and, to a lesser extent, high speeds. It is a mathematically intensive field covering most aspects of applied mathematics, from Partial Differential equations to Numerical Analysis and Complex Analysis. Two of the central areas of research within this particular branch of fluid dynamics are the boundary-layer laminar-turbulent transition and the boundary-layer separation. Both of these phenomena have a high impact on the aerodynamic performance of aircraft wings, turbine blades and other fast-moving objects such as rockets. As a consequence, their study is relevant both for industrial applications and to the scientific community as a whole. The mathematical element pertaining to the analysis of these two phenomena is the consistent use of asymptotic methods, such as matched asymptotic expansions and multiple scales analysis. In particular, this work will be based on the viscous-inviscid interaction theory originally discovered by Lin (1955) and further developed by the work of Neiland (1969) and Stewartson & Williams (1969). In the first chapter of this thesis, we will study the initial stages of the laminar-turbulent transition of a compressible boundary layer on a swept wing. The instability of interest will be the stationary crossflow vortex, which is known to be the main instability mode in three-dimensional boundary layers on a swept wing. We will focus on two specific aspects of the transition process, namely the receptivity and linear stability analysis of the flow. The receptivity mechanism introduced in our work is a roughness of size comparable with that of the boundary layer thickness. This justifies our restriction to the study of the inviscid instability of the flow and the use of the impermeability condition on the roughness. The remaining two chapters are concerned with the viscous-inviscid interaction of the boundary layer in the vicinity of a surface discontinuity. We will first study the behaviour of the subsonic flow exposed to the singular pressure gradient dp/dx = κ(x0 − x)−1/3, as x → x0. It forms when the body contour has a point x = x0 near which yw = (x0 − x)5/3. We will show how logarithmic terms need to be included in the solution. We then study a similar problem, this time in the context of an incoming transonic flow near a point of curvature discontinuity. We will show that in both cases the boundary layer experiences an “extreme acceleration”.Open Acces

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