L'Institut de Recherches sur les Fruits et Agrumes 1942-1984 : de l'IFAC à l'IRFA

Ce rapport fournit quelques éléments pour un bilan et ravive la mémoire par un rappel historique et géographique de la naissance de l'IFAC, de sa croissance, puis de l'ultime phase de dépendance croissante à son intégration dans un organisme de plus grande dimension. Tout au long de ses 40 années d'existence, l'activité de l'IRFA a été répartie en quatre programmes consacré aux agrumes, à l'ananas, aux bananiers et aux plantains et aux autres fruitier

Improvement of the guiding performances of near infrared organic/inorganic channel waveguides

New sol-gel derived organic/inorganic hybrid single mode waveguides devices have been developed for telecommunication applications in the two near infrared windows at 1310 and 1550 nm. The overall procedure of fabrication of these devices is described and the refractive indices of the guiding, the buffer and the protective layers are adjusted by a precise control of the materials' composition. Due to the improvement of the composition of the guiding layer, the attenuation losses are significantly decreased to 0.8 dB/cm and 2dB/cm at respectively 1310 and 1550 nm

Neutrinos in flat extra dimension: towards a realistic scenario

We consider the simple extension of the Standard Model in which an additional right handed neutrino propagates along a flat extra dimension, while the Standard Model fields are confined on a 3-brane. The fifth dimension is $S^1/Z_2$ orbifold compactified. In this scenario, the neutrino mass can be naturally suppressed. By studying systematically the fundamental parameter space, we show that the strong phenomenological constraints on mixing angles between active and sterile neutrinos (especially those derived from the SNO experiment data) do not conflict with the possibility of generating a realistic neutrino mass spectrum. As a second step, we explore the possibility of a successful leptogenesis through the decays of the Kaluza-Klein excitations of the right handed neutrino.Comment: 16 pages, 2 ps figure

Scarron, Le Roman comique

Cours sur Le Roman comique de Scarron. I. Un roman en pleine vogue du burlesque. II. Errances et circulation dans la composition du roman. III. Un roman sur l\u27écritur

Viral markers of hepatitis B, C and D and HB vaccination status of a health care team in a rural district of Cameroon

UNLABELLED: Ninety-three health care workers (HCW) in the Tokombere sahelian district volunteered to participate in a trial to investigate viral markers of hepatitis B, C, and D and HB vaccination status. METHODS: . Sera were tested using the Vikia HBsAg kit followed by CMIA for detection of HBsAg, anti-HBs, anti-HBc, and anti-HCV. HBsAg-positive HCW were tested for HBV-DNA, anti-HDV, and, if positive for anti-HDV, HDV-RNA.RESULTS: Analysis of anti-HBc positivity indicated that 91% of HCW had been infected by HBV, regardless of vaccination history. Vikia HBsAg results were confirmed by chemiluminescent microparticle immunoassay (CMIA) in all HCW and were positive in 17 HCW with virus load >2000 IU/mL in 6 and HDV co-infection in 6. Anti-HCV was found in 6 HCW. Among the 55 HCW that had not been vaccinated, only 3 needed vaccination because of anti-HBc negativity. Among HCW considered for HBV treatment, one patient presenting HBV/HDV co-infection was excluded after diagnosis of hepatocarcinoma. CONCLUSION: Systematic HB vaccination of new HCW appears unnecessary in this rural region of Africa. Anti-HBc screening is cost-effective for identifying HCW requiring vaccination. Vikia HBsAg is effective for point-of-care screening. We underline the need for universal early (preferably neonatal) HB vaccination and for availability of anti-HBV drug in limited-resource countries

Successful Yukawa structures in Warped Extra Dimensions

For a RS model, with SM fields in the bulk and the Higgs boson on the TeV-brane, we suggest two specific structures for the Yukawa couplings, one based on a permutation symmetry and the other on the Universal Strength of Yukawa couplings hypothesis (USY). In USY, all Yukawa couplings have equal strength and the difference in the Yukawa structure lies in some complex phase. In both scenarios, all Yukawa couplings are of the same order of magnitude. Thus, the main features of the fermion hierarchies are explained through the RS geometrical mechanism, and not because some Yukawa coupling is extremely small. We find that the RS model is particularly appropriate to incorporate the suggested Yukawa configurations. Indeed, the RS geometrical mechanism of fermion locations along the extra dimension, combined with the two Yukawa scenarios, reproduces all the present experimental data on fermion masses and mixing angles. It is quite remarkable that in the USY case, only two complex phases of definite value +-Pi/2 are sufficient to generate the known neutrino mass differences, while at same time, permitting large leptonic mixing in agreement with experiment.Comment: 11 page

Top-quark rare decay t→cht\to c h in R-parity-violating SUSY

The flavor-changing top-quark decay $t\to c h$, where $h$ is the lightest CP-even Higgs boson in the minimal supersymmetric standard model, is examined in the R-parity-violating supersymmetric model. Within the existing bounds on the relevant R-parity-violating couplings, the branching fraction for $t\to c h$ can be as large as about $10^{-5}$ in some part of the parameter space.Comment: version to appear in Phys. Lett.

Strategic review of enhancements and culture-based fisheries

Enhancements are interventions in the life cycle of common-pool aquatic resources. Enhancement technologies include culture-based fisheries, habitat modifications, fertilization, feeding and elimination of predators/competitors. Enhancements are estimated to yield about two million mt per year, mostly from culture-based fisheries in fresh waters where they account for some 20 percent of capture, or 10 percent of combined capture and culture production. Marine enhancements are still at an experimental stage, but some have reached commercial production. Enhancements use limited external feed and energy inputs, and can provide very high returns for labour and capital input. Moreover, enhancement initiatives can facilitate institutional change and a more active management of aquatic resources, leading to increased productivity, conservation and wider social benefits. Enhancements may help to maintain population abundance, community structure and ecosystem functioning in the face of heavy exploitation and/or environmental degradation. Negative environmental impacts may arise from ecological and genetic interactions between enhanced and wild stocks. Many enhancements have not realised their full potential because of a failure to address specific institutional, technological, management and research requirements emanating from two key characteristics. Firstly, enhancement involves investment in common-pool resources and can only be sustained under institutional arrangements that allow regulation of use and a flow of benefits to those who bear the costs of enhancement. Secondly, interventions are limited to certain aspects of the life cycle of stocks, and outcomes are strongly dependent on natural conditions beyond management control. Hence, management must be adapted to local conditions to be effective, and certain conditions may preclude successful enhancement altogether. Governments have a major role to play in facilitating enhancement initiatives through the establishment of conducive institutional arrangements, appropriate research support, and the management of environmental and other impacts on and from enhancements.<br /

Sub-microsecond correlations in photoluminescence from InAs quantum dots

Photon correlation measurements reveal memory effects in the optical emission of single InAs quantum dots with timescales from 10 to 800 ns. With above-band optical excitation, a long-timescale negative correlation (antibunching) is observed, while with quasi-resonant excitation, a positive correlation (blinking) is observed. A simple model based on long-lived charged states is presented that approximately explains the observed behavior, providing insight into the excitation process. Such memory effects can limit the internal efficiency of light emitters based on single quantum dots, and could also be problematic for proposed quantum-computation schemes.Comment: 8 pages, 8 figure

KK Parity in Warped Extra Dimension

We construct models with a Kaluza-Klein (KK) parity in a five- dimensional warped geometry, in an attempt to address the little hierarchy problem present in setups with bulk Standard Model fields. The lightest KK particle (LKP) is stable and can play the role of dark matter. We consider the possibilities of gluing two identical slices of 5D AdS in either the UV (IR-UV-IR model) or the IR region (UV-IR-UV model) and discuss the model-building issues as well as phenomenological properties in both cases. In particular, we find that the UV-IR-UV model is not gravitationally stable and that additional mechanisms might be required in the IR-UV-IR model in order to address flavor issues. Collider signals of the warped KK parity are different from either the conventional warped extra dimension without KK parity, in which the new particles are not necessarily pair-produced, or the KK parity in flat universal extra dimensions, where each KK level is nearly degenerate in mass. Dark matter and collider properties of a TeV mass KK Z gauge boson as the LKP are discussed.Comment: 35 pages, 11 figure