Stability of Dissipative Optical Solitons in the 2D Complex Swift-Hohenberg Equation

International audienceThis article deals with stationary localized solutions of the (2D) two-dimensional complex Swift-Hohenberg equation (CSHE). Our approach is based on the semi-analytical method of collective coordinate approach. According to the parameters of the equation and a suitable choice of ansatz, the stationary dissipative solitons of the 2D CSHE equation are mapped. This approach allows to describe the influence of the parameters of the equation on the various physical parameters of the pulse and their dynamics. Finally, the major impact of spectral filtering terms on the dynamic of the solitons is demonstrated

Earthworm Grazed-Trichoderma harzianum Biofortified Spent Mushroom Substrates Modulate Accumulation of Natural Antioxidants and Bio-Fortification of Mineral Nutrients in Tomato

The present investigation was aimed at evaluating the impact of earthworm grazed and Trichoderma harzianum biofortified spent mushroom substrate (SMS) on natural antioxidant and nutritional properties of tomato. Results of the investigation reveal that earthworm grazing and T. harzianum bio-fortification led to significant improvement in the physico-chemical properties of fresh SMS and its application increased the accumulation of natural antioxidants and mineral content in tomato as compared to either T. harzianum biofortified SMS or fresh SMS. In particular, the earthworm grazed, T. harzianum biofortified SMS (EGTHB-SMS) was found to inhibit lipid peroxidation and protein oxidation with significant increase in total polyphenol and flavonoid content in tomato. Further, it increased Fe2+/Fe3+ chelating activity, superoxide anion radical scavenging activity compared to other treatments. The results thus suggest an augmented elicitation of natural antioxidant properties in tomato treated with EGTHB-SMS, resulting in a higher radical scavenging activity, that is highly desirable for human health. In addition, the use of SMS to enhance the nutritional value of tomato fruits becomes an environment friendly approach in sustainable crop production

The challenge of improving soil fertility in yam cropping systems of West Africa

Published online: 21 Nov 2017Yam (Dioscorea spp.) is a tuber crop grown for food security, income generation, and traditional medicine. This crop has a high cultural value for some of the groups growing it. Most of the production comes from West Africa where the increased demand has been covered by enlarging cultivated surfaces while the mean yield remained around 10 t tuber ha−1. In West Africa, yam is traditionally cultivated without input as the first crop after a long-term fallow as it is considered to require a high soil fertility. African soils, however, are being more and more degraded. The aims of this review were to show the importance of soil fertility for yam, discuss barriers that might limit the adoption of integrated soil fertility management (ISFM) in yam-based systems in West Africa, present the concept of innovation platforms (IPs) as a tool to foster collaboration between actors for designing innovations in yam-based systems and provide recommendations for future research. This review shows that the development of sustainable, feasible, and acceptable soil management innovations for yam requires research to be conducted in interdisciplinary teams including natural and social sciences and in a transdisciplinary manner involving relevant actors from the problem definition, to the co-design of soil management innovations, the evaluation of research results, their communication and their implementation. Finally, this research should be conducted in diverse biophysical and socio-economic settings to develop generic rules on soil/plant relationships in yam as affected by soil management and on how to adjust the innovation supply to specific contexts

The Comparative Economics of Catch-Up in Output per worker, total factor productivity and technological gain in Sub-Saharan Africa

After investigating the effect of external financial flows on total factor productivity and technological gain, we use the beta catch-up and sigma convergence to compare dispersions in output per worker, total factor productivity and technological gain in Sub-Saharan Africa (SSA) for the years 1980-2010. The comparative evidence is articulated with income levels, years of schooling, and health factors. We find; first, a positive association between foreign direct investment, trade openness, foreign aid, remittances and total factor productivity. However, when foreign direct investment is interacted with schooling, it is direct effect becomes negative on total factor productivity. Second, beta catch-up is between19.22% and 19.70% per annum with corresponding time to full catch-up of 25.38 years and 26.01 years respectively. Third, we find sigma-convergence among low-income nations and upper-middle income nations separately, but not for the entire sample together. Fourth, schooling in SSA is not yet a significant source of technology, but it can make external financial inflows more effective. Policies to induce external financial flows are not enough for development if absorptive capacity is low. More policy implications are discussed

Activite Nycthemerale De Oryctes monoceros Olivier (Coleoptera : Dynastidae) En Côte D\'ivoire

L\'insecte (Oryctes monoceros (Coleoptera, Dynastidae) est connu pour ses dégâts importants sur les cultures de cocotiers et de palmiers à huile en Côte d\'Ivoire. Pour connaître les périodes d\'activité de cet insecte, une étude a été menée pendant 7 jours sur des individus adultes issus de pièges, de vieux stipes et de cocotiers vivants. Les insectes collectés ont été mis dans des carafes transparentes contenant des rafles de palmier à huile et nourris avec la canne à sucre. Le dénombrement des insectes en activité tentatives d\'envol, accouplements et alimentation) a été fait toutes les heures, la température et les jours de pluie ont été relevés. Les résultats révèlent une forte activité entre 20 h et 2 h pour les individus de sexes différents. Aussi, les mâles sont-ils plus actifs que les femelles et les couples. Néanmoins, ces différentes périodes d\'activité ont varié en fonction du lieu de collecte des insectes et aussi des facteurs climatiques. Les insectes issus des pièges sont plus actifs que ceux des vieux stipes et des cocotiers vivants. L\'activité de O. monoceros a été négativement influencée par la pluie lorsque celle-ci survint entre 20 h et 3 h et aussi par des températures nocturnes supérieures à 25 °C. La connaissance des périodes d\'activité des insectes peut être utilisée en olfactométrie pour améliorer la capture de O. monoceros avec la phéromone dans les plantations de cocotiersOryctes monoceros (Coleoptera : Dynastidae) causes very significant damages in coconut and palm tree crops in Côte d\'Ivoire. To assess the activity period of this insect, a 7-days study was conducted on adult individuals obtained from traps, old stems and living coconut trees. The collected insects were put in transparent bottles containing pieces of empty fruit, bunches of palm tree and fed with sugarcane. The counting of insects in activity (tentatives of flying, matings and feeding) was done every hour, while noting temperature and rainy days. This study reveals high insects activities with both sexes, between 8 p.m. and 2 a.m. Males were more active than females and couples. Nevertheless, these periods of activity varied according to the trapping place and weather conditions. The insects from the traps were more active than those from the old stems and the living coconut trees. The activity of O. monoceros was negatively affected by rain occuring between 8 p.m. and 3 a.m., and also by night temperature above 25 ° C. The knowledge of the activity periods of the insect can be used in olfactometry to improve its capture with the pheromone in coconut plantations. Keywords: Oryctes monoceros, cocotiers, période d'activité, pluviométrie, Côte d'IvoireAgronomie Africaine Vol. 19 (1) 2007: pp. 71-7