Existence and Uniqueness of a Transient State for the Coupled Radiative-Conductive Heat Transfer Problem

This paper deals with existence and uniqueness results for a transient nonlinear radiative-conductive system in three-dimensional case. This system describes the heat transfer for a grey, semi-transparent and non-scattering medium with general boundary conditions. We reformulate the full transient state system as a fixed-point problem. The existence and uniqueness proof is based on Banach fixed point theorem.Comment: 16 page

ABC likelihood-freee methods for model choice in Gibbs random fields

Gibbs random fields (GRF) are polymorphous statistical models that can be used to analyse different types of dependence, in particular for spatially correlated data. However, when those models are faced with the challenge of selecting a dependence structure from many, the use of standard model choice methods is hampered by the unavailability of the normalising constant in the Gibbs likelihood. In particular, from a Bayesian perspective, the computation of the posterior probabilities of the models under competition requires special likelihood-free simulation techniques like the Approximate Bayesian Computation (ABC) algorithm that is intensively used in population genetics. We show in this paper how to implement an ABC algorithm geared towards model choice in the general setting of Gibbs random fields, demonstrating in particular that there exists a sufficient statistic across models. The accuracy of the approximation to the posterior probabilities can be further improved by importance sampling on the distribution of the models. The practical aspects of the method are detailed through two applications, the test of an iid Bernoulli model versus a first-order Markov chain, and the choice of a folding structure for two proteins.Comment: 19 pages, 5 figures, to appear in Bayesian Analysi

Public governance as a key determinant of FDI : a comparative analysis of sub-saharan Africa and south-east Asia host countries

The World Bank (2000), in its report on Quality of Growth emphasises the importance of public governance as the keystone of a country's development. Studies examining determinants of foreign direct investment (FDI) are also increasingly taking account of such fundamentals as institutional and political factors. Thus, rule of law, bureaucratic corruption, educational attainment or quality of physical infrastructure are now included in econometric analyses next to more common variables such as market size, labour costs or trade openness. In other words, good governance appears to be a key condition for attracting FDI. For instance, Lehmann (1999), shows that a country like India could increase its share of US affiliates' physical investment by 50% if it were to eliminate all political uncertainty. For a developing country, the stakes for improving its public governance are high. Beyond an increase in its growth rate, a favourable business climate is likely to attract more FDI and enhance their alleged spillovers. More FDI means more financial resources for the host country, whereas it is likely that the technological intensity of these investments and the transfer of foreign know-how to domestic firms will largely depend on the quality of public governance. This article has three goals. First, to clarify why public governance is likely to influence FDI inflows. Second, to propose a new evaluation of public governance through the construction of quantitative, relatively objective, easily replicable and sample-specific indicators. The public governance of two geographic zones will be assessed through this method: Sub-Saharan Africa (SSA) and South-East Asia (SEA). As shown in table 1.1, the former attracts much less FDI than the latter. Third, to test econometrically whether public governance explains the diverging abilities of SSA and SEA to attract FDI

La pérennité des peuplements insulaires laurentiens : le cas de l’île Saint-Ignace et de l’île Dupas

Depuis les débuts de la colonie, le peuplement des îles du Saint-Laurent situées à l'aval de Montréal a été l'objet de changements brusques. L'examen de l'évolution de la population des six îles (ou groupes d'îles) laurentiennes encore habitées en permanence, trahit la situation de dépendance dans laquelle ont évolué ces lieux à la fois particuliers et à la fois témoins et acteurs du peuplement de l'axe laurentien. À ce titre, le cas de l'île d'Anticosti est sûrement le plus éloquent. Quoique moins spectaculaire, l'évolution des autres populations insulaires laurentiennes (Cent-îles du lac Saint-Pierre, île d'Orléans, île aux Grues, île aux Coudres et île Verte) a également été mouvementée. Toutes à un moment ou un autre de leur histoire (exemples : île d'Orléans vers 1871 ; île aux Coudres vers 1956) ont vu leur population rurale atteindre un taux de saturation qui a été suivi d'une chute souvent brutale des effectifs insulaires. L'île d'Orléans et les Cent-îles sont les seules où s'est éventuellement opéré un regain démographique grâce à une réadaptation de la fonction insulaire. L'étude comparative de l'évolution récente de deux municipalités de cet archipel contribue à illustrer le paradoxe de l'insularité : la pérennité des peuplements insulaires laurentiens ne peut être assurée que dans des conditions impliquant l'érosion des caractères culturels qui définissent le milieu insulaire même.Ever since the early colony, the settlement of the islands of the St. Lawrence has withstood sharp changes. The evolution of the population of the six settled islands (or group of islands) lying between Montréal and Anticosti underlines the nature of the dependency under which these localities have survived as actors and spectators of the development of the laurentian axis. The case of Anticosti island is probably the most eloquent. Although less spectacular, the growth of the population of the other islands {Cent-lles of lake St. Peter, lie d'Orléans, Ile aux Grues, lie aux Coudres and lie Verte) has also been erratic. All of them, at one point or another (examples : lie d'Orléans around 1871 ; Ile aux Coudres around 1956) have seen their rural population reach a level of saturation generally followed by a sharp drop in the total population of the island community. Only the lie d'Orléans and Cent-Îles have been the object of a new demographic « take-off » thanks to a readaptation of their function. The comparative study of the recent demographic history of the two municipalities of the Cent-Îles group contributes to illustrate the paradox of insularity : the permanency of the insular settlements of the St. Lawrence can only be safeguarded under conditions implying the erosion of the cultural characters that define the originality of these insular localities

Analyse et simulation topologiques en géographie, application à l’étude des migrations interrégionales

Le modèle d'Analyse et de Simulation Topologique est à l'analyse de système ce que l'analyse de régression multiple est à l'analyse multivariée. Pour un système de flux ce modèle détermine les gains effectués par tous les noeuds dépendants pour tout changement de flux dans le noeud principal ; il détermine l'importance des diverses lignes de transmission entre les éléments et il permet de connaître la sensibilité d'un élément aux variations de flux sur tout arc du réseau. C'est un modèle qui pourrait s'avérer très utile pour des études d'interdépendance systémique ou pour une recherche sur les lignes de transmissions d'un phénomène de diffusion. C'est une technique très intéressante également pour mesurer l'évolution d'un réseau et connaître les éléments qui ont tendance à être refoulés en marge du système par d'autres qui prennent de l'importance.À titre d'illustration, le modèle a été appliqué à l'étude des migrations de populations en France pour les années 1962-68, dans le cadre des régions de programme.The A.S.T. model, Analyse et Simulation Topologique, does for system analysis what multiple regression does for multivariate analysis. For an origin-destination table this model determines the gains effected by the dependent elements of the System for any change in the independent ; it calculates the transmission links and gains, and it also establishes the sensitivity of any element to fluctuations in any arc of the network. It is a model which should prove of considerable interest for studies of repercussion effects of flow fluctuations, or for the analysis of transmission flows in a diffusion process. It should also prove of value for the study of the evolution of a system to establish which elements are gaining in influence and which are being relegated to the outer fringes.As an illustration, the model was applied to the study of the flow patterns of French migrant populations for the period 1962-68, by planning region

Some complexity and approximation results for coupled-tasks scheduling problem according to topology

We consider the makespan minimization coupled-tasks problem in presence of compatibility constraints with a specified topology. In particular, we focus on stretched coupled-tasks, i.e. coupled-tasks having the same sub-tasks execution time and idle time duration. We study several problems in framework of classic complexity and approximation for which the compatibility graph is bipartite (star, chain,. . .). In such a context, we design some efficient polynomial-time approximation algorithms for an intractable scheduling problem according to some parameters

Coherent Population Trapping Resonances in Buffer Gas-filled Cs Vapor Cells with Push-Pull Optical Pumping

We report on a theoretical study and experimental characterization of coherent population trapping (CPT) resonances in buffer gas-filled vapor cells with push-pull optical pumping (PPOP) on Cs D1 line. We point out that the push-pull interaction scheme is identical to the so-called lin per lin polarization scheme. Expressions of the relevant dark states, as well as of absorption, are reported. The experimental setup is based on the combination of a distributed feedback (DFB) diode laser, a pigtailed intensity Mach-Zehnder electro-optic modulator (MZ EOM) for optical sidebands generation and a Michelson-like interferometer. A microwave technique to stabilize the transfer function operating point of the MZ EOM is implemented for proper operation. A CPT resonance contrast as high as 78% is reported in a cm-scale cell for the magnetic-field insensitive clock transition. The impact of the laser intensity on the CPT clock signal key parameters (linewidth - contrast - linewidth/contrast ratio) is reported for three different cells with various dimensions and buffer gas contents. The potential of the PPOP technique for the development of high-performance atomic vapor cell clocks is discussed.Comment: 28 pages, 12 figure