Absolutely Continuous Compensators

We give sufficient conditions on the underlying filtration such that all totally inaccessible stopping times have compensators which are absolutely continuous. If a semimartingale, strong Markov process X has a representation as a solution of a stochastic differential equation driven by a Wiener process, Lebesgue measure, and a Poisson random measure, then all compensators of totally inaccessible stopping times are absolutely continuous with respect to the minimal filtration generated by X. However Cinlar and Jacod have shown that all semimartingale strong Markov processes, up to a change of time and space, have such a representation

Braving the waves: The economics of clandestine migration from Africa

Illegal immigration from the developing world to rich countries is one of the most controversial topics today. Using a unique data set on potential illegal migrants collected in Dakar, Senegal, we characterize the preferences and characteristics of illegal migrants, and the manner in which these factors interact so as to yield observed behavior. On the basis of our theoretical model, we evaluate a measure of the time and risk preferences through the individual discount rates and the individual coefficients of absolute risk aversion. Then, we test empirically our theoretical propositions and we show that these variables play a role, in the illegal migration decision, in the willingness to pay a smuggler and in the choice of the method of migration, at least as important as "classical" migration determinants such as the expected wage in the host country.Illegal Migration; Preferences; Expectations

Braving the waves: The economics of clandestine migration from Africa

Illegal immigration from the developing world to rich countries is one of the most controversial topics today. Using a unique data set on potential illegal migrants collected in Dakar, Senegal, we characterize the preferences and characteristics of illegal migrants, and the manner in which these factors interact so as to yield observed behavior. On the basis of our theoretical model, we evaluate a measure of the time and risk preferences through the individual discount rates and the individual coefficients of absolute risk aversion. Then, we test empirically our theoretical propositions and we show that these variables play a role, in the illegal migration decision, in the willingness to pay a smuggler and in the choice of the method of migration, at least as important as "classical" migration determinants such as the expected wage in the host country

Band or Point Inflation Targeting? An Experimental Approach

We conduct laboratory experiments with human subjects to test the rationale of adopting a band versus point inflation targeting regime. Within the standard New Keynesian model, we evaluate the macroeconomic performances of both regimes according to the strength of shocks affecting the economy. We find that when the economy faces small shocks, the average level of inflation as well as its volatility are significantly lower in a band targeting regime, while the output gap and interest rate levels and volatility are significantly lower in a point targeting regime with tolerance bands. However, when the economy faces large shocks, choosing the suitable inflation targeting regime is irrelevant because both regimes lead to comparable performances. These findings stand in contrast to those of the literature and question the relevance of clarifying a mid-point target within the bands, especially in emerging market economies more inclined to large and frequent shocks

Inflation Targeting under Heterogeneous Information and Sticky Prices

Under what conditions should a central bank adopt an inflation targeting regime ? This is the main question we address in this paper. A large part of the literature puts forward that these regimes should have to be adopted, as they yield higher macroeconomic performances. We analyze the issue of optimal inflation targeting in a new theoretical framework, which conciliates the interaction between the degree of price stickiness, and the degree of strategic complementarities in fi-rms' price setting. We show that adopting a target for inflation, crucially depends on the sequential but complementary importance of the model's parameters. In particular, we show that strategic complementarities appear to be the fi-rst driving force. When they are low, the central bank must adopt an inflation targeting regime whatever the importance of other parameters in the model. By contrast, when the degree of strategic complementarities is high, adopting a target for in ation depends on both the degree of price stickiness and the precision of central bank's information about the fundamentals of the economy. When prices are exible enough, adopting an inflation target is never optimal. However, when prices are strongly sticky, and the central bank holds precise information about the fundamentals, the central bank should adopt an explicit target for inflation

Does Inflation Targeting Matter ? An Experimental Investigation

We use laboratory experiments with human subjects to test the relevance of di-fferent inflation targeting regimes. In particular and within the standard New Keynesian model, we evaluate to what extent communication of the inflation target is relevant to the success of inflation targeting. We -find that if the central bank only cares about inflation stabilization, announcing the inflation target does not make a difference in terms of macroeconomic performances compared to a standard active monetary policy. However, if the central bank also cares about the stabilization of the economic activity, communicating the target helps to reduce the volatility of inflation, interest rate, and output gap although their average levels are not aff-ected. This finding is consistent with those of the theoretical literature and provides a rationale for the adoption of a flexible inflation targeting regime

Investigation of resonators loaded periodic structures

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2006."February 2006."Includes bibliographical references (leaves 71-74).The study of metamaterials has brought about new changes in modern microwave communication systems. As predicted by Veselago some 37 years ago, substances which exhibit simultaneously, negative permittivity ([epsilon]) and negative permeability ([mu]) over a certain range of frequencies would display some unusual phenomena such as backward waves, reversed refraction, backward Cerenkov radiation, and negative refractive index. Because of these new features of left handed materials, many structures such as split rings resonators (SRR) have been proposed in the literature to artificially fabricate radio frequency and microwave components. Due to their bulk properties, periodic arrays of SRRs provide a negative permeability. Therefore under the fundamental limit of effective medium theory that the dimensions of the lattice are much smaller than the wavelength, we can treat the array of SRRs as bulk material and retrieve its effective parameters.(cont.) Also because of size reduction and selective passband transmission spectra in planar geometry, split rings resonators are designed under the fundamental limit (dimensions of one-tenth of the wavelength or smaller), and as a result they constitute better candidates than their L-C loaded transmission lines counterparts for microwaves applications. The generalized formula for impedance-loaded transmission line is derived. The dispersion characteristic and impedance of structures with periodic resonators are analyzed as well.by M'baye Diao.S.M

Traitement contre les nématodes dans le bassin arachidier Nord du Sénégal

Le traitement au dibromochloropropane (DBCP) autorise des augmentations de rendements spectaculaires chez l'arachide en première année de rotation, puis sur les cultures suivantes. Ces résultats mis en évidence par les nématologistes de l'ORSTOM et la Direction de la protection des végétaux sénégalaise ont été jugés suffisamment prometteurs pour mettre en route une opération de recherche développement dont le but est de définir une technique permettant l'utilisation de la fumigation en milieu paysan. Au bout de trois années c'est chose faite et l'on peut penser à une nouvelle extension. Le changement de conditions amené par le traitement tant au point de vue production que système agraire pose comme préalable la connaissance des techniques culturales et de l'environnement qu'il a fallu étudier de ce point de vue phytosanitair

Etude quantitative de quelques pigments de la Spiruline cultivée en Mauritanie en vue d’une valorisation nutritionnelle

La spiruline est une cyanobactérie comestible, extrêmement riche en protéine, en acides gras essentiels, en vitamines et en divers oligo- éléments. Elle est utilisée pour lutter contre la malnutrition infantile. Dans le but d'élucider les pigments constitutifs de la Spiruline cultivée en Mauritanie, des campagnes de prélèvements ont été effectuées. Cinquante un (51) échantillons de spiruline dont vingt huit (28) échantillons sous forme de spaghettis et Vingt trois (23) sous forme de poudre ont été prélevés d’Octobre à Décembre 2010. Les résultats de ces analyses ont montré que l’humidité qui caractérise la teneur en eau dans la spiruline varie de 5,1 à 9,6%, la teneur en cendre varie de 7,1 à 10,2%. La teneur en protéine est remarquablement élevée et varie de 51% à 87,5% par rapport au poids sec. La teneur en phycocyanines oscille entre 46% et 53%. Les valeurs des caroténoïdes varient de 5,43 mg/g à 8,93 mg/g. La spiruline peut être actuellement l'une des meilleures solutions pour la production simple d'un complément alimentaire de haute qualité.Mots clés: Spiruline, protéines, phycocyanines, caroténoïdes, Mauritani