MICROFINANCE INSTITUTIONS UNDER INTEREST RATES CEILINGS

Microfinance institutions (MFIs) have grown fast in WAEMU surprising political decision makers. They reacted by setting up in the late 90's, a specific legislation. A legal usury rate for credits was defined fixing the borrower ceiling interest rate at 27 percent per year for microfinance institutions and 18 percent for banks. This statutory frame, fast elaborated, revealed early its incapacities and therefore, weakened structures in charge of the regulation of the sector. This structure is confronted with the difficult choice to maintain institutions outside the statutory frame or to apply a rigorous supervision and to precipitate a massive decline of MFIs. This law limits incentives to better governance, the efficiency and the flexibility expected from a good statutory frame. This paper models the behaviour of microfinance institutions in the context of interest rate ceilings and requirement of a minimal level of governance. We use comparative statics to show that a relaxation of the constraint on the usury rate does not lead necessarily to an increase of the borrower interest rate.regulation, usury ; governance ; microfinance

A Semi-parametric Two-component “Compound” Mixture Model and Its Application to Estimating Malaria Attributable Fractions

Malaria remains a major epidemiological problem in many developing countries. Malaria is dened as the presence of parasites and symptoms (usually fever) due to the parasites. In endemic areas, an individual may have symptoms attributable either to malaria or to other causes. From a clinical point of view, it is important to correctly diagnose an individual who has developed symptoms so that the appropriate treatments can be given. From an epidemiologic and economic point of view, it is important to determine the proportion of malaria affected cases in individuals who have symptoms so that policies on intervention programmes can be developed. Once symptoms have developed in an individual, the diagnosis of malaria can be based on analysis of the parasite levels in blood samples. However, even a blood test is not conclusive as in endemic areas, many healthy individuals can have parasites in their blood slides. Therefore, data from this type of studies can be viewed as coming from a mixture distribution, with the components corresponding to malaria and nonmalaria cases. A unique feature in this type of data, however, is the fact that a proportion of the non-malaria cases have zero parasite levels. Therefore, one of the component distribu-tions is itself a mixture distribution. In this article, we propose a semi-parametric likelihood approach for estimating the proportion of clinical malaria using parasite level data from a group of individuals with symptoms. Our approach assumes the density ratio for the parasite levels in clinical malaria and non-clinical malaria cases can be modeled using a logistic model. We use empirical likelihood to combine the zero and non-zero data. The maximum semi-parametric likelihood estimate is more ecient than existing non-parametric estimates using only the frequencies of zero and non-zero data. On the other hand, it is more robust than a fully parametric maximum likelihood estimate that assumes a parametric model for the non-zero data. Simulation results show that the performance of the proposed method is satisfactory. The proposed method is used to analyze data from a malaria survey carried out in Tanzania.Attributable fraction; Density ratio model; Empirical likelihood; Malaria; Mixture methods.

Emergent hyperuniformity in periodically-driven emulsions

We report the emergence of large-scale hyperuniformity in microfluidic emulsions. Upon periodic driving confined emulsions undergo a first-order transition from a reversible to an irreversible dynamics. We evidence that this dynamical transition is accompanied by structural changes at all scales yielding macroscopic yet finite hyperuniform structures. Numerical simulations are performed to single out the very ingredients responsible for the suppression of density fluctuations. We show that as opposed to equilibrium systems the long-range nature of the hydrodynamic interactions are not required for the formation of hyperuniform patterns, thereby suggesting a robust relation between reversibility and hyperuniformity which should hold in a broad class of periodically driven materials.Comment: 5p, 3f, submitte

Effect of body temperature of heavy broiler breeders on resistance to heat of their progeny

This trial aimed at studying the effects of the body temperature (BT) of heavy broiler breeders (HBB) on the productive parameters and the resistance to heat of the broilers of their progeny. The experiment was done on two phases: (1) measurements on breeders were done in the commercial hatchery, whereas (2) the tests on broilers were done in the poultry unit of UCV. In phase 1, 280 HBB of line L1 (Ross x Ross) and 280 HBB of line L2 (Hybro) were tested for their rectal body temperature (BT) and level of hyperventilation (LH) during periods of high ambient temperature. The animals were split into two groups: higher BT (HBT, 41.26±0.01°C) and lower BT (LBT, 40.9±0.08°C). Egg production, fertility and hatchability were recorded. A total of 400 chicks (100 of lower of higher parent BT for both lines) were raised in same environmental conditions, and tested for BT, LH and productive parameters. Egg production did not differ between breeders HBT or LBT. Fertility was significantly higher in L2 (98.5±0.08) than in L1 (96.02±0.61). In phase 2 weight gain, feed intake and feed conversion did not differ between animals issued from lower or higher BT parents. At day 36 during a heat challenge (TA=37°C), the BT of animals from L2 issued from parents of higher BT was higher (43.2±0.092 vs 42.7 ± 0.08, p<0.01) whereas this difference was not significant in line L1. Mortality during heat challenge was also 40% higher for these animals. These results suggest than there can be a heritability of BT characteristics, which could have an effect on the resistance of broilers to heat stress. (Résumé d'auteur

Safely Optimizing Highway Traffic with Robust Model Predictive Control-based Cooperative Adaptive Cruise Control

Road traffic crashes have been the leading cause of death among young people. Most of these accidents occur when the driver becomes distracted due to fatigue or external factors. Vehicle platooning systems such as Cooperative Adaptive Cruise Control (CACC) are one of the results of the effort devoted to the development of technologies for decreasing the number of road crashes and fatalities. Previous studies have suggested such systems improve up to 273\% highway traffic throughput and fuel consumption in more than 15\% if the clearance between vehicles in this class of roads can be reduced to 2 meters. This paper proposes an approach that guarantees a minimum safety distance between vehicles taking into account the overall system delays and braking capacity of each vehicle. A $l\infty$-norm Robust Model Predictive Controller (RMPC) is developed to guarantee the minimum safety distance is not violated due to uncertainties on the lead vehicle behavior. A formulation for a lower bound clearance of vehicles inside a platoon is also proposed. Simulation results show the performance of the proposed approach compared to a nominal controller when the system is subject to both modeled and unmodeled disturbances.Comment: Submitted to Transactions on Intelligent Transportation System

A Linear Sigma Model with Three Flavors and Vector and Axial-Vector Mesons

We outline the extension of the globally chirally invariant Nf = 2 linear sigma model with vector and axial-vector degrees of freedom to Nf=3. We present preliminary results concerning the scalar meson masses.Comment: Prepared for the Proceedings of the 11th International Workshop on Meson Production, Properties and Interaction (MESON 2010), in Krakow, Poland, 10-15 June 2010. Three page

Identification of point defects in HVPE-grown GaN by steady-state and time-resolved photoluminescence

We have investigated point defects in GaN grown by HVPE by using steady-state and time-resolved photoluminescence (PL). Among the most common PL bands in this material are the red luminescence band with a maximum at 1.8 eV and a zero-phonon line (ZPL) at 2.36 eV (attributed to an unknown acceptor having an energy level 1.130 eV above the valence band), the blue luminescence band with a maximum at 2.9 eV (attributed to ZnGa), and the ultraviolet luminescence band with the main peak at 3.27 eV (related to an unknown shallow acceptor). In GaN with the highest quality, the dominant defect-related PL band at high excitation intensity is the green luminescence band with a maximum at about 2.4 eV. We attribute this band to transitions of electrons from the conduction band to the 0/+ level of the isolated CN defect. The yellow luminescence (YL) band, related to transitions via the −/0 level of the same defect, has a maximum at 2.1 eV. Another yellow luminescence band, which has similar shape but peaks at about 2.2 eV, is observed in less pure GaN samples and is attributed to the CNON complex. In semi-insulating GaN, the GL2 band with a maximum at 2.35 eV (attributed to VN) and the BL2 band with a maximum at 3.0 eV and the ZPL at 3.33 eV (attributed to a defect complex involving hydrogen) are observed. We also conclude that the gallium vacancy-related defects act as centers of nonradiative recombination