Propagation of Casuarina equisetifolia through axillary buds of immature female inflorescences cultured in vitro

The study of the actinorhizal symbiosis in #Casuarina equisetifolia$ requires an homogenous plant material. Consequently, we devised a method of micropropagation based on the use of immature female inflorescences (IFI) as explants. IFI excised from an adult tree formed multiple buds after 4-week incubation on Murashige and Skoog medium with 0.05 micromol 1-1 NAA and 11.1 micromol 1-1 BAP. The axillary buds evolved into 5-6 cm long shoots 5 weeks after the transfer of IFI on a similar medium except for the addition of activated charcoal. Rooting of the shoots was obtained on a third medium, without BAP or charcoal, but with 1 micromol 1-1 NAA. The plantlets were transferred into soil. Their growth was satisfactory and no plagiotropic tendency was observed. (Résumé d'auteur

Le reboisement au Sénégal : bilan des réalisations de 1993 à 1998

La production de plants au Sénégal, toutes espèces confondues, a régressé de 46% entre 1993 et 1998 et reste dominée par les espèces forestières (77% des productions). Les espèces exotiques à croissance rapide sont les plus demandées par les populations locales. Durant cette période, le taux annuel de reboisement est évalué à 13 679 ha. Ce taux est nettement inférieur au taux de déboisement estimé à 50 000 ha/an. Les plantations massives représentent l'essentiel des réalisations de ces dernières années et concernent essentiellement les plantations villageoises et communautaires. L'effort national de reboisement est en baisse constante et les superficies plantées ont diminué de 38%. Cette situation est en grande partie liée à la récession économique et à la régression de près de 60% des réalisations des projets de développement forestier qui assurent plus de 58% des superficies plantées. La situation actuelle du secteur forestier découles de contraintes d'ordre économique, méthodoloqique, technique et institutionnelle qui sont discutées dans cette étude. (Résumé d'auteur

Аналитический метод решения нестационарных дифференциальных игр сближения

Досліджено ігрову задачу зближення для нестаціонарних динамічних процесів, що функціонують в умовах невизначеності та протидії. При цьому термінальна множина представляє собою циліндричне багатозначне відображення. На основі методу розв’язуючих функцій отримано достатні умови завершення гри в класі квазі- та стробоскопічних стратегій для різних схем методу. Проведено порівняння гарантованих часів. Результати ілюструються на моделі з інтегральним блоком керування та ігрових задачах з простим рухом.The game problem of pursuit is studied for dynamic processes evolving under uncertainty and counteraction. The terminal set is supposed to be a cylindrical set-valued mapping. The method of resolving functions is used to derive the sufficient conditions for the game termination in the class of quasi- and stroboscopic strategies for various schemes of the method. The guaranteed times are compared. The results are illustrated using the model with integral control unit and game problems with simple motion

Shady business: understanding the spatial ecology of exophilic Anopheles mosquitoes

Background: Understanding the ecology of exophilic anophelines is a key step toward developing outdoor control strategies to complement existing indoor control tools against malaria vectors. This study was conducted to assess the movement pattern of exophilic Anopheles mosquitoes between blood meal sources and resting habitats, and the landscape factors dictating their resting habitat choice. Results: Resting clay pots were placed at 5 m, 25 m, 50 m, 75 m and 100 m away from isolated focal houses, radiating from them in four directions. The locations of the clay pots represent heterogeneous land cover types at a relatively fine spatial scale in the landscape. The effect of the landscape characters on the number of both female and male anophelines caught was modelled using zero-inflated negative binomial regression with a log link function. A total of 420 Anopheles mosquitoes (353 females and 67 males) belonging to three species; Anopheles arabiensis, Anopheles pharoensis, and Anopheles tenebrosus were caught in the resting clay pots, with An. arabiensis being the dominant species. Canopy cover, distance from the house, and land cover type were the significant landscape characters influencing the aggregation of resting mosquitoes. Both the count and binary models showed that canopy cover was the strongest predictor variable on the counts and the presence of Anopheles mosquitoes in the clay pots. Female Anopheles were most frequently found resting in the pots placed in banana plantations, and at sampling points that were at the greater distances (75 m and 100 m) from the focal house. Conclusions: This study showed that exophilic Anopheles mosquitoes tend to rest in shaded areas some distance away from human habitation. These findings are important when targeting mosquitoes outdoors, complementing the existing effort being made to control malaria vectors indoors

Влияние интенсивности механической активации на структуру гексагонального нитрида бора

Изучено влияние интенсивности механической активации на микроструктуру и свойства гексагонального нитрида бора (hBN).Вивчено вплив інтенсивності механічної активації на мікроструктуру і властивості гексагонального нітриду бору (hBN).The mechanical activation intensity effect on the microstructure and properties of hexagonal boron nitride (hBN) has been studied