Efficacité Du Kaolin (Kalaba) Dans La Gestion Intégrée Des Chenilles Endocarpiques Du Cotonnier Dans La Zone Centre Du Bénin

The study on the efficacy of Kaolin in the integrated management of the endocarpiques larvae of cotton was undertaken in the center of Benin. The objective of the work was to evaluate the potentiality of Kaolin in the control of some endocarpiques larvae of the cotton plant. To achieve this goal, a Fisher block device with 4 treatments and 4 repetitions were set up on two sites. The treatments developed consisted of an untreated plot ; a plot treated with Lambdacyalothrine 15 g/l - chlorpyrifos ethyl 300 g/l; a plot treated with kaolin 5% and another one with the mixture kaolin + Lambdacyalothrine 15 g/l - chlorpyrifos ethyl 300 g/l. The treatment with kaolin was achieved with a back, maintained pressure sprayer. Ten applications were conducted with the kaolin used alone and 6 with the other objects. Results showed that there is no significant difference between the average number of larvae recorded in the plots treated with kaolin and plots which served as control of reference (Lambdacyalothrine 15 g/l - chlorpyrifos ethyl 300 g/l at 1 l/ha). It was the same for the percentage of attacked green capsules and cotton seed production. The effect of kaolin in the control of Haritalodes derogata was low (11.6% of plants attacked against 0.1 % for the chemical reference control and 22.9 % for the untreated plot). The results of Kaolin associated with the binary acaricide, showed that the number of endocarpiques larvae has been significantly reduced compared to the reference control. This study indicates that kaolin can be used like other biological pesticides, as alternative to chemical control and then, constituted an important component of the integrated cotton pests management

Spin-to-Orbital Angular Momentum Conversion in Semiconductor Microcavities

We experimentally demonstrate a technique for the generation of optical beams carrying orbital angular momentum using a planar semiconductor microcavity. Despite being isotropic systems, the transverse electric - transverse magnetic (TE-TM) polarization splitting featured by semiconductor microcavities allows for the conversion of the circular polarization of an incoming laser beam into the orbital angular momentum of the transmitted light field. The process implies the formation of topological entities, a pair of optical half-vortices, in the intracavity field

Evolution de la diversité des cultivars de fonio pratiqués dans la commune de Boukoumbé au Nord-Ouest du Bénin

Afin de comparer la diversité actuelle des écotypes de fonio à celle cultivée dix (10) ans plus tôt au Bénin, une enquête a été menée en 2013 dans la commune de Boukoumbé. Dans chacun des vingt (20) villages prospectés, un focus groupe d’une douzaine de producteurs a été à chaque fois enquêté. Cinq (5) à dix (10) producteurs sont ensuite entretenus individuellement à l’aide d’un questionnaire semi-structuré pour recueillir des informations sur les cultivars, leurs noms locaux, leurs principales caractéristiques, et la gestion des semences. Les résultats ont confirmé la diversité des appellations et ont permis de recenser cinq (5) cultivars différenciés par la précocité, la couleur des racèmes, les tailles de graines et de plantes. Les semences, transmises surtout de génération en génération, sont prélevées à 99% sur les récoltes précédentes. Près de 95% des enquêtés cultivent une seule variété à la fois. La plus forte diversité a été rencontrée chez les "Ditamaris" des villages de Boukoumbé-centre et Natta. "Iporapia" et "Takotapuaka" sont cultivés par toutes les ethnies. La diversité décrite dix (10) ans plus tôt dans la zone a été maintenue. Toutefois, les variétés de précocités extrêmes sont de moins en moins cultivées, et donc menacées de disparition.© 2015 International Formulae Group. All rights reserved.Mots clés: Espèce négligée, accession de fonio, Digitalia spp., conservation in situ, amélioration variétale, BéninEnglish Title: Evolution of the diversity of fonio cultivars practiced in the commune of Boukoumbe in North-West of BeninEnglish AbstractTo compare the current diversity of landraces of millet fonio to that cultivated ten (10) years ago in Benin, a survey was conducted in 2013 in the district of Boukoumbé. In each of the twenty (20) villages surveyed a focus group of a dozen producers was investigated every time. Then, five (5) to ten (10) producers are individually interviewed using a semi-structured questionnaire to collect information on cultivars, their local names, their main characteristics and seed management. The results confirmed the diversity of names and allowed to identify five cultivars differentiated by the earliness, color of racemes, sizes of seeds and plant height. Seeds, especially transmitted from generation to generation, are taken at 99% on the previous harvest. Nearly 95% of respondents grow only one variety at a time. The greatest diversity was encountered among the "Ditamaris" of villages in Boukoumbé center and Natta. "Iporapia" and "Takotapuaka" are cultivated by all ethnic groups. The diversity described ten (10) years earlier in the area has been maintained. However, the extreme precocity varieties are lesser and lesser grown, and therefore at risk of extinction.© 2015 International Formulae Group. All rights reserved.Keywords: Neglected species, accession of fonio, Digitaria spp, in situ conservation, plant breeding, Beni

Vortices in polariton OPO superfluids

This chapter reviews the occurrence of quantised vortices in polariton fluids, primarily when polaritons are driven in the optical parametric oscillator (OPO) regime. We first review the OPO physics, together with both its analytical and numerical modelling, the latter being necessary for the description of finite size systems. Pattern formation is typical in systems driven away from equilibrium. Similarly, we find that uniform OPO solutions can be unstable to the spontaneous formation of quantised vortices. However, metastable vortices can only be injected externally into an otherwise stable symmetric state, and their persistence is due to the OPO superfluid properties. We discuss how the currents charactering an OPO play a crucial role in the occurrence and dynamics of both metastable and spontaneous vortices.Comment: 40 pages, 16 figure

The Rapid Degradation of Lambda-Cyhalothrin Makes Treated Vegetables Relatively Safe for Consumption.

Lambda-cyhalothrin (λ-cyhalothrin) is the most commonly used pyrethroid insecticide for vegetable farming in Benin. This insecticide is misused and overused by farmers, and hence may pose health hazards to consumers. We monitored λ-cyhalothrin residues in lettuce and cabbage from farms at the market gates in Cotonou and Parakou using high performance liquid chromatography (HPLC) analysis techniques. These residues were also monitored on samples directly from farms (on-farm sampling) for 14 days post-treatment. Potential factors such as photolysis and hydrolysis involved in λ-cyhalothrin degradation were also screened. Results revealed that the level of λ-cyhalothrin residue concentrations in lettuce from Houeyiho decreased from 4.2 mg/kg on Day 1 to about 0.2 mg/kg on Day 7. On Day 9, analyzed lettuces were all λ-cyhalothrin free. In contrast, even 14 days after treatment of cabbage from Bawera (Parakou), we still recorded the presence of λ-cyhalothrin residues in analyzed samples. For samples from market gates, λ-cyhalothrin residues were found in lettuce from two markets out of the nine surveyed in Cotonou. Interestingly, none of these contaminated samples had residues above the maximum residue limit for lettuce (MRL = 0.5 mg/kg). Similarly, in Parakou, samples from all five surveyed vegetable markets were contaminated with λ-cyhalothrin residues at concentrations below the MRL for cabbage (MRL = 0.2 mg/kg). We conclude that λ-cyhalothrin residues in lettuce and cabbage from farms and markets in Parakou and Cotonou are within the MRL, and hence are relatively safe for consumption

Simplified intensity- and phase-modulated transmitter for modulator-free decoy-state quantum key distribution

Quantum key distribution (QKD) allows secret key exchange between two users with unconditional security. For QKD to be widely deployed, low cost and compactness are crucial requirements alongside high performance. Currently, the majority of QKD systems demonstrated rely on bulk intensity and phase modulators to generate optical pulses with precisely defined amplitude and relative phase difference i.e., to encode information as signal states and decoy states. However, these modulators are expensive and bulky, thereby limiting the compactness of QKD systems. Here, we present and experimentally demonstrate a novel optical transmitter design to overcome this disadvantage by generating intensity- and phase-tunable pulses at GHz clock speeds. Our design removes the need for bulk modulators by employing directly modulated lasers in combination with optical injection locking and coherent interference. This scheme is, therefore, well suited to miniaturization and photonic integration, and we implement a proof-of-principle QKD demonstration to highlight potential applications

Nano-Opto-Electro-Mechanical Systems

A new class of hybrid systems that couple optical, electrical and mechanical degrees of freedom in nanoscale devices is under development in laboratories worldwide. These nano-opto-electro-mechanical systems (NOEMS) offer unprecedented opportunities to dynamically control the flow of light in nanophotonic structures, at high speed and low power consumption. Drawing on conceptual and technological advances from cavity optomechanics, they also bear the potential for highly efficient, low-noise transducers between microwave and optical signals, both in the classical and quantum domains. This Progress Article discusses the fundamental physical limits of NOEMS, reviews the recent progress in their implementation, and suggests potential avenues for further developments in this field.Comment: 27 pages, 3 figures, 2 boxe