Motivation et maintien de la paix : Élaboration d’un lien entre agir et structure

Le maintien de la paix multilatéral est, de plus en plus fréquemment, le moyen par lequel la communauté internationale répond aux conflits violents, qu’ils soient internes ou entre États. L’étude du maintien de la paix requiert des investigations transnationales et multi-sites dont l’importance est croissante en anthropologie. En dépit de ce fait, peu d’études anthropologiques du maintien de la paix ont été réalisées. Cet article prolonge un programme ininterrompu de recherche anthropologique sur le maintien de la paix. Il utilise la théorie de l’inversion psychologique pour interpréter des données ethnographiques recueillies par l’Organisme des Nations Unies chargé de la surveillance de la trêve (ONUST). Dans le maintien de la paix, les actions individuelles sont liées, dans un processus d’implications mutuelles, à des schémas à grande échelle de légitimité et d’efficacité du maintien de la paix. L’analyse présentée ici crée un échafaudage théorique permettant de connecter l’analyse des motivations au niveau individuel à un exposé de l’inversion culturelle dans le maintien de la paix à de plus hauts niveaux d’organisation sociale.Multilateral peacekeeping is an increasingly important way that the international community responds to violent conflicts within and between states. Studying peacekeeping requires transnational, multisided investigation, which is increasingly important for anthropology. Despite this, there have been few anthropological studies of peacekeeping. This paper extends an ongoing program of anthropological research on peacekeeping. This paper uses psychological reversal theory to interpret ethnographic data collected from the United Nations Truce Supervision Organization. Individual actions in peacekeeping are linked in a mutually implicative process to broad-scale patterns of peacekeeping legitimacy and effectiveness. The analysis presented here creates a theoretical scaffolding to connect the analysis of motivation at an individual level to a cultural inversion account of peacekeeping at higher levels of social organization.El mantenimiento multilateral de la paz es el medio que, con mayor frecuencia, utiliza la comunidad internacional en tanto que respuesta a los conflictos violentos, sean internos o entre naciones. El estudio del mantenimiento de la paz exige investigaciones trasnacionales y multi-situacionales, que son cada día más importantes en antropología. A pesar de ello, se han realizado pocos estudios antropológicos sobre el mantenimiento de la paz. Este artículo prolonga un continuo programa de investigación antropológica sobre el mantenimiento de la paz. Utiliza la teoría de la inversión sicológica en la interpretación de los datos etnográficos recogidos por la Organización de la Naciones Unidas encargada de la vigilancia de la tregua (ONUVT). En el mantenimiento de la paz, las acciones individuales están ligadas, al interior de un proceso de implicaciones mutuas, con esquemas a gran escala de legitimidad y eficacia del mantenimiento de la paz. El análisis que aquí se presenta, propone un andamiaje teórico que permite conectar el análisis de las motivaciones a escala individual con una explicación de la inversión cultural en el mantenimiento de la paz a niveles más altos de la organización socia

Investigation of methods to produce a uniform cloud of fuel particles in a flame tube

The combustion of a uniform, quiescent cloud of 30-micron fuel particles in a flame tube was proposed as a space-based, low-gravity experiment. The subject is the normal- and low-gravity testing of several methods to produce such a cloud, including telescoping propeller fans, air pumps, axial and quadrature acoustical speakers, and combinations of these devices. When operated in steady state, none of the methods produced an acceptably uniform cloud (+ or - 5 percent of the mean concentration), and voids in the cloud were clearly visible. In some cases, severe particle agglomeration was observed; however, these clusters could be broken apart by a short acoustic burst from an axially in-line speaker. Analyses and experiments reported elsewhere suggest that transient, acoustic mixing methods can enhance cloud uniformity while minimizing particle agglomeration

Topological analysis of polymeric melts: Chain length effects and fast-converging estimators for entanglement length

Primitive path analyses of entanglements are performed over a wide range of chain lengths for both bead spring and atomistic polyethylene polymer melts. Estimators for the entanglement length N_e which operate on results for a single chain length N are shown to produce systematic O(1/N) errors. The mathematical roots of these errors are identified as (a) treating chain ends as entanglements and (b) neglecting non-Gaussian corrections to chain and primitive path dimensions. The prefactors for the O(1/N) errors may be large; in general their magnitude depends both on the polymer model and the method used to obtain primitive paths. We propose, derive and test new estimators which eliminate these systematic errors using information obtainable from the variation of entanglement characteristics with chain length. The new estimators produce accurate results for N_e from marginally entangled systems. Formulas based on direct enumeration of entanglements appear to converge faster and are simpler to apply.Comment: Major revisions. Developed near-ideal estimators which operate on multiple chain lengths. Now test these on two very different model polymers

Parametric Study of Decay of Homogeneous Isotropic Turbulence Using Large Eddy Simulation

Numerical simulations of decaying homogeneous isotropic turbulence are performed with both low-order and high-order spatial discretization schemes. The turbulent Mach and Reynolds numbers for the simulations are 0.2 and 250, respectively. For the low-order schemes we use either second-order central or third-order upwind biased differencing. For higher order approximations we apply weighted essentially non-oscillatory (WENO) schemes, both with linear and nonlinear weights. There are two objectives in this preliminary effort to investigate possible schemes for large eddy simulation (LES). One is to explore the capability of a widely used low-order computational fluid dynamics (CFD) code to perform LES computations. The other is to determine the effect of higher order accuracy (fifth, seventh, and ninth order) achieved with high-order upwind biased WENO-based schemes. Turbulence statistics, such as kinetic energy, dissipation, and skewness, along with the energy spectra from simulations of the decaying turbulence problem are used to assess and compare the various numerical schemes. In addition, results from the best performing schemes are compared with those from a spectral scheme. The effects of grid density, ranging from 32 cubed to 192 cubed, on the computations are also examined. The fifth-order WENO-based scheme is found to be too dissipative, especially on the coarser grids. However, with the seventh-order and ninth-order WENO-based schemes we observe a significant improvement in accuracy relative to the lower order LES schemes, as revealed by the computed peak in the energy dissipation and by the energy spectrum

Adaptive Importance Sampling in General Mixture Classes

In this paper, we propose an adaptive algorithm that iteratively updates both the weights and component parameters of a mixture importance sampling density so as to optimise the importance sampling performances, as measured by an entropy criterion. The method is shown to be applicable to a wide class of importance sampling densities, which includes in particular mixtures of multivariate Student t distributions. The performances of the proposed scheme are studied on both artificial and real examples, highlighting in particular the benefit of a novel Rao-Blackwellisation device which can be easily incorporated in the updating scheme.Comment: Removed misleading comment in Section

Small Scale Response and Modeling of Periodically Forced Turbulence

The response of the small scales of isotropic turbulence to periodic large scale forcing is studied using two-point closures. The frequency response of the turbulent kinetic energy and dissipation rate, and the phase shifts between production, energy and dissipation are determined as functions of Reynolds number. It is observed that the amplitude and phase of the dissipation exhibit nontrivial frequency and Reynolds number dependence that reveals a filtering effect of the energy cascade. Perturbation analysis is applied to understand this behavior which is shown to depend on distant interactions between widely separated scales of motion. Finally, the extent to which finite dimensional models (standard two-equation models and various generalizations) can reproduce the observed behavior is discussed

Open TURNS: An industrial software for uncertainty quantification in simulation

The needs to assess robust performances for complex systems and to answer tighter regulatory processes (security, safety, environmental control, and health impacts, etc.) have led to the emergence of a new industrial simulation challenge: to take uncertainties into account when dealing with complex numerical simulation frameworks. Therefore, a generic methodology has emerged from the joint effort of several industrial companies and academic institutions. EDF R&D, Airbus Group and Phimeca Engineering started a collaboration at the beginning of 2005, joined by IMACS in 2014, for the development of an Open Source software platform dedicated to uncertainty propagation by probabilistic methods, named OpenTURNS for Open source Treatment of Uncertainty, Risk 'N Statistics. OpenTURNS addresses the specific industrial challenges attached to uncertainties, which are transparency, genericity, modularity and multi-accessibility. This paper focuses on OpenTURNS and presents its main features: openTURNS is an open source software under the LGPL license, that presents itself as a C++ library and a Python TUI, and which works under Linux and Windows environment. All the methodological tools are described in the different sections of this paper: uncertainty quantification, uncertainty propagation, sensitivity analysis and metamodeling. A section also explains the generic wrappers way to link openTURNS to any external code. The paper illustrates as much as possible the methodological tools on an educational example that simulates the height of a river and compares it to the height of a dyke that protects industrial facilities. At last, it gives an overview of the main developments planned for the next few years

Estimation of cosmological parameters using adaptive importance sampling

We present a Bayesian sampling algorithm called adaptive importance sampling or Population Monte Carlo (PMC), whose computational workload is easily parallelizable and thus has the potential to considerably reduce the wall-clock time required for sampling, along with providing other benefits. To assess the performance of the approach for cosmological problems, we use simulated and actual data consisting of CMB anisotropies, supernovae of type Ia, and weak cosmological lensing, and provide a comparison of results to those obtained using state-of-the-art Markov Chain Monte Carlo (MCMC). For both types of data sets, we find comparable parameter estimates for PMC and MCMC, with the advantage of a significantly lower computational time for PMC. In the case of WMAP5 data, for example, the wall-clock time reduces from several days for MCMC to a few hours using PMC on a cluster of processors. Other benefits of the PMC approach, along with potential difficulties in using the approach, are analysed and discussed.Comment: 17 pages, 11 figure

Action Anthropology and Pedagogy: University-Community Collaborations in Setting Policy

This article describes a student-led, community-participatory project focused on reducing the burden of childhood lead poisoning in rental housing. A multidisciplinary group of students and faculty worked with community members. We compiled the social, public health, economic, and policy information on the human and fiscal costs of childhood lead poisoning. This analysis was done for community advocates to use to persuade policymakers to enact a local law strengthening the prevention of childhood lead poisoning in rental property. In conducting this work, the students gained experience in qualitative research methods, quantitative data analysis, the health consequences of lead exposure, health policy, urban health, science writing, and public presentation

In and Out of Equilibrium II: Evolution in Repeated Games with Discounting and Complexity Costs

We explore evolutionary dynamics for repeated games with small, but positive complexity costs. To understand the dynamics, we extend a folk theorem result by Cooper (1996) to continuation probabilities, or discount rates, smaller than 1. While this result delineates which payoffs can be supported by neutrally stable strategies, the only strategy that is evolutionarily stable, and has a uniform invasion barrier, is All D. However, with sufficiently small complexity costs, indirect invasions - but now through 'almost neutral' mutants - become an important ingredient of the dynamics. These indirect invasions include stepping stone paths out of full defection