Stability of the Structure of the Technical Coefficients: Hybrid Estimator Approach

Les comptes nationaux ont été, pendant longtemps, l’une des préoccupations majeures dans la production de statistiques économiques au sein de l’administration publique sénégalaise. Les travaux de la comptabilité nationale s’intéressent beaucoup à la production statistique des comptes et d’autres tableaux synthétiques comme le Tableau Economique d’Ensemble et le Tableau des Entrées Intermédiaires (TEI). Le TEI, conçu grâce à la détermination des coefficients techniques, met en exergue les interrelations entre les différentes branches d’activités. La présente étude s’inspire des travaux de Leontief [1927] sur les modèles input-output et propose une démarche synthétique permettant de calculer des coefficients techniques robustes, ainsi que leurs intervalles de confiance. Les données utilisées proviennent d’une compilation des Tableaux Entrées Sorties (TES) de 1980 à 2004. Pour assurer la robustesse des résultats, un estimateur hybride, combinaison optimale de la moyenne et de la médiane a été privilégié. Les résultats obtenus mettent en évidence, une bonne adéquation entre les intervalles estimés et les données réelles observées. Les simulations faites dans le cas d’une flambée du prix du baril en 2005, répliquent assez bien la réalité observée dans la structure économique au Sénégal.Estimateur hybride; coefficients techniques; modèle input output

Are neighbors welcome ? e-buyer search, price competition and coalition strategy in the Internet retailing

On étudie les forces qui régissent l'agrégation des sites Web marchands (B-to-C) en concurrence sur un marché électronique différencié, où le coût de recherche pour les consommateurs est indépendant du coût d'adaptation/transport supporté lorsque le bien trouvé ne correspond pas à leur préférence. On s'intéresse à la possibilité pour les sites Internet de se coaliser, ce qui se traduit par une réduction du coût de recherche pour trouver d'autres sites à l'intérieur de la coalition. On effectue la statique comparative des structures de coalitions (en fonction du degré de différenciation de ses partenaires) lorsque les sites se font une concurrence en prix. On montre qu'un site préfère se coaliser avec un partenaire fortement différencié et fixe dans ce cas un prix unique plus bas.En vendant au détail;Coûts de recherche;Coalition

Overview of the mean of production used for FSW

The Friction Stir welding process is now introduced in production plants. More and more applications are developed and the most part of the work is now centered on the mean of production to be used. Institut de Soudure and Arts et Métiers ParisTech are working on this subject since mid of 2005. The results of this work is a recognize knowledge on the methodology for qualifying a Friction Stir Welding Equipment [1]. In the same time, and based on this work, Institut de Soudure has bought a new kind of Friction Stir Welding machine based on a KUKA Robot

Experimental investigation of the influence of the FSW plunge processing parameters on the maximum generated force and torque

The paper presents the results of an experimental investigation, done on the friction stir welding (FSW) plunging stage. Previous research works showed that the axial force and torque generated during this stage were characteristic for a static qualification of a FSW machine. Therefore, the investigation objectives are to better understand the relation between the processing parameters and the forces and torque generated. One of the goals is to find a way to reduce the maximum axial force and torque occurring at the end of the plunging stage in order to allow the use of a flexible FSW machine. Thus, the influence of the main plunge processing parameters on the maximum axial force and torque are analysed. In fact, forces and torque responses can be influenced by the processing parameter. At the end, a diagram presenting the maximum axial force and torque according to the processing parameters is presented. It is an interesting way to present the experimental results. This kind of representation can be useful for the processing parameters choice. They can be chosen according to the force and torque responses and consequently to the FSW machine capacities

Estimation of the Equilibrium Interest Rate: Case of CFA zone

Problem Statement The framework of this study is consisted of the countries of zone CFA and in fact the two central banks (BCEAO and BEAC) in charge of the monetary policy implementation. There was a great resurgence of interest these last years on the question in the way of leading the monetary policy. One of the indicators of this phenomenon is the enormous volume of recent papers and the conferences prepared on this subject. In addition, much of macro economists proposed specific rules of policy or ruled on the way in which the monetary policy should be led. The principal objective of this study is the evaluation of the macroeconomic gold rule in the CFA countries which stipulates that in an economy with equilibrium growth and under simplifying macroeconomic assumptions: the neutral interest rate is equal to the potential growth rate of the economy. Research Method To achieve this objective we try to determine the weight of the goals of monetary and fiscal policies attaches with a quadratic reaction function which takes into account a target of inflation, public expenditure and interest rate. And then the methodology of determination of the neutral interest rate is derived from a generalized Taylor rule. The estimation of the parameters is based on panel data econometrics, the generalized method of moments and the Kalman filter. These different methods are used to emphasize the robustness of the results of our analysis. Results and conclusion The estimates carried out on the panel data emphasize a neutral interest rate in the interval of 1.4% to 1.6%. It is generally noticed that the estimates made on the panel data are compatible with those carried out by using the Kalman filter. In addition, it is observed that, overall the level of the natural interest rate in UEMOA zone (1.51) is lower than CEMAC zone (1.65). The most important neutral rate is observed in the Malian economy and the lowest in the Burkina economy. But we notice a larger homogeneity in CEMAC zone (standard deviation of 0.12) than UEMOA zone ( standard deviation of 0.29).Taylor Rule; equilibrium interest rate; Kalman filter

Are neighbors welcome ? e-buyer search, price competition and coalition strategy in the Internet retailing

We study the forces that drive the phenomenon of aggregation of merchant Web sites (B-to-C) competing in a differentiated electronic market, where the search cost for the consumers is independent from the adaptation/transportation cost they incur when the good they find does not match with their preference. We focus on the possibility for Internet sites to coalesce, which results in a reduction of the search cost to find other sites within the coalition. We do the static comparative of coalition structures (depending on whether there is little or high differentiation between partners), when firms compete in price. We find that firms prefer to coalesce with highly differentiated partners, and set in this case lower prices.On étudie les forces qui régissent l'agrégation des sites Web marchands (B-to-C) en concurrence sur un marché électronique différencié, où le coût de recherche pour les consommateurs est indépendant du coût d'adaptation/transport supporté lorsque le bien trouvé ne correspond pas à leur préférence. On s'intéresse à la possibilité pour les sites Internet de se coaliser, ce qui se traduit par une réduction du coût de recherche pour trouver d'autres sites à l'intérieur de la coalition. On effectue la statique comparative des structures de coalitions (en fonction du degré de différenciation de ses partenaires) lorsque les sites se font une concurrence en prix. On montre qu'un site préfère se coaliser avec un partenaire fortement différencié et fixe dans ce cas un prix unique plus bas

Consumers' Search Cost and Emerging Structure of Web Sites Coalitions : a multi-agent based simulation of an electronic market

On développe un modèle multi-agent, extension d'un modèle analytique qui étudie la structure des coalitions de sites B-to-C, lorsque les consommateurs-internautes ont un coût de recherche pour trouver le bien qui correspond à leur préférence, et lorsque les coalitions de sites permettent de réduire ces coûts de recherche via des moteurs de recherche spécialisés. Ce modèle multi-agent comporte des agents hétérogènes à rationnalité limitée: sites et internautes, dont on défini l'état et les règles de comportement. Notre objectif est de faire des simultations qui mettent en jeu ces deux types d'agents (une populations de sites marchands et une population de consommateurs), de les faire intéragir à travers une procédure de recherche des consommateurs et un processus de formation des coalitions des sites, et d'observer la dynamique du système, en particulier en ce qui concerne la structure de coalition émergente. Le modèle multi-agent étends ainsi les résultats obtenus dans le modèle analytique, avec des hypothèses moins restrictives. En plus du processus de formation des coalitions, le modèle théorique se voit aussi enrichi par d'autres règles de comportement pour les sites (entrée sur le marché, faillite), ce qui apporte des enseignements sur la dynamique de la concurrence lorsque la formation des coalition permet d'accroître la demande au détriment des sites peu ou non coalisées.Commerce électronique;Multi-agents;formation de coalitions

The effects of physical activity on adipose tissue metabolism and DNA methylation

"May 2009"Vita.The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file.Thesis (Ph. D.) University of Missouri-Columbia 2009.The increased prevalence of obesity and diabetes threatens both the real and economic health of Western counties. There were two major goals of this dissertation, 1) to determine if in response to inactivity and hyperphagia there is a decrease in fatty acid oxidation and mitochondria concentration in WAT, similar to skeletal muscle and liver and 2) to determine if physical active and sedentary mice have differentially methylated DNA in skeletal muscle. First, (chapter 2) I established that the increase in abdominal WAT during inactivity occurs even when food intake is restricted to the level of always-sedentary animals. A follow-up study (chapter 3) showed that the increase in WAT is not associated with a decrease in acid oxidation adipocytes fatty. Markers of WAT mitochondrial protein content (cytochrome c, COXIV-subunit I, and citrate synthase activity) significantly increased from 13 to 40 weeks in the wild type rats, were significantly attenuated in the hyperphagic sedentary rats, but were partially restored to the wild type levels with wheel running in the hyperphagic rats. Although strong evidence suggests that differences in DNA methylation in physically active and sedentary animals can occur, I was unable to verify candidate genes selected based on initial microarrays. However, two novel physical activity responsive genes were found, Dnmt3a and Pitx3. Future studies are needed to examine the feasibility of differences in DNA methylation occurring in response to physical activity. In summary, WAT oxidative phenotype is modified by aging and physical activity, while it remains unclear whether DNA methylation differences in skeletal muscle can occur.Includes bibliographical reference

Qualification of a robotized Friction Stir Welding System

This paper presents an experimental methodology to determine a Friction Stir Welding (FSW) means of production based on the experimental study of the tool / material mechanical interactions generated during the welding operation. These two stages have been identified as being characteristic for the qualification of a FSW equipment. This paper presents the experimental results of the parametric study done on the plunging and welding phases. Ranges of forces and torques diagrams were established according to the processing parameters, in order to qualify a means of production and select the process parameters allowing the operation on the available FSW equipment

Determining the ability of a high payload robot to perform FSW applications

This paper presents an experimental methodology to determine a Friction Stir Welding (FSW) means of production based on the experimental study of the tool / material mechanical interactions generated during the welding operation. These two stages have been identified as being characteristic for the qualification of a FSW equipment. This paper presents the experimental results of the parametric study done on the plunging and welding phases. Ranges of forces and torques diagrams were established according to the processing parameters, in order to qualify a means of production and to select the processing parameters allowing the operation on the available FSW equipment