Production halieutique du Lac Fae (bassin du San Pedro) en region Sud-ouest de la Cote d'Ivoire

L'etude, realisee de septembre 1996 a decembre 1997, dans le cadre du Projet d'Etude Participative AISA/IDESSA, a permis de caracteriser la production halieutique du lac Fae. Celle-ci a essentiellement porte sur les poissons (135,27 t) et les crevettes (4,40 t). La production globale obtenue, tous taxons confondus, a ete de 139,67 t, pour la periode d'etude. Le genre Chrysichthys a ete le plus dominant dans les prises et a represente 61,4 % des captures. Ence qui concerne la production crevettiere, celle-ci a concerne l'espece Macrobranchium vollenhovenii Herklots, 1851. La production enregistree en 1997 a ete de 105,442 et 3,486 t pour les poissons et les crevettes, respectivement. En terme de chiffre d'affaire, avec un prix de vente du poisson entre 1000 et 1750 FCFA/kg, ces captures rapporteraient entre 105.442 et 184,523 millions de F CFA pour les poissons, et environ 5,229 millions de FCFA pour la production crevettiere, a raison de 1500 F/kg.Mots-cles : Lac Fae, peche artisanale, effort de peche, production, Cote d' Ivoir

Production de Oreochromis niloticus avec des aliments à base de sousproduits agricoles

Des alevins de Oreochromis niloticus (0,7 ± 0,06 g) ont été nourris dans seize étangs avec quatre aliments dont trois aliments tests (A1, A2 et A3) formulés uniquement à base de sous-produits agricoles. La composition de ces aliments tests est la suivante : A1 (tourteaux de soja, de coton, sons de maïs et de mil) ; A2 (tourteaux de soja, de coton, sons de maïs et de riz) et A3 (tourteaux de soja, de coton, sons de mil et de riz). Le quatrième (At), contenant de la farine de poisson, est un produit industriel et a servi de témoin. Deux densités de mise en charge (10 et 13 ind./m2 ) ont été appliquées pour chaque traitement alimentaire. Chaque densité d\'élevage a été répliquée une fois. Après 120 jours d\'élevage, tous les poissons ont atteint au moins 25 g (poids seuil de sexage). Les meilleures performances zootechniques sont obtenues avec l\'aliment A1, suivi de l\'aliment A2. Les poids moyens finaux observés aux densités 10 et 13 ind./m2 sont de 54,69 ± 7,76 et 46,77 ± 5,87 g (A1), 46,32 ± 6,71 et 41,23 ± 5,32 g (A2) ; 40,90 ± 7,64 et 37,31 ± 5,73 g (A3) puis de 41,72 ± 6,57 et 37,45 ± 5,84 g (At). Les quotients nutritifs respectifs correspondants sont de 1,13 ; 1,30 ; 1,87 et 1,72 (10 ind. /m2), puis de 1,40 ; 1,63 ; 1,74 et 1,80 (13 ind. /m2). Les aliments A1 et A2 permettent un niveau de production supérieur à celui du témoin. Comparés au témoin, des taux de réduction respectifs de 30 % et d\'environ 14 à 37% des coûts des aliments tests et de production des fingerling ont été obtenus..Alevins of Oreochromis niloticus (0.7 ± 0,06 g) were fed with three test diets (A1, A2 and A3) formulated using agricultural by-products and a commercial one containing fish meal (control diet = At). The composition of these test diets is: A1 (oilcakes of soy, of cotton, bran of corn and of millet); A2 (oilcakes of soy, of cotton, bran of corn and of rice) and A3 (oilcakes of soy, of cotton, bran of millet and of rice). Two stocking densities (10 and 13 ind. / m2) were applied for each experimental diet. At the end of 120 days of rearing, all experimental fish reached more than 25g (doorstep weight for manual sexing). Diets A1 and A2 displayed the better growth and food utilization performances. Final mean weight of fish at stocking densities 10 and 13 ind. / m2 respectively, ranged from 54.69 ± 7.76 to 46.77 ± 5.87 g (A1), 46.32 ± 6.71 to 41.23 ± 5.32 g (A2); 40.90 ± 7.64 to 37.31 ± 5.73 g (A3) and 41.72 ± 6.57 to 37.45 ± 5.84 g (At). The corresponding food conversion rates were 1.13; 1.30; 1.87 and 1.72 (10 ind. /m2), then 1.40; 1.63; 1.74 and 1.80 (13 ind. /m2). Test diets A1 and A2 produced more yield than the control one. Relatively to the assessment economic aspect, test diets reduce the diet cost and fingerlings production cost, respectively of rate about 30 % and 14 to 37 %, compared to that of the control diet. Keywords: Oreochromis niloticus, feeding, agricultural by-products, production, Côte d\'Ivoire.Sciences & Nature Vol. 5 (1) 2008: pp. 89-9

Spatial distribution and structure of benthic macroinvertebrates in an artificial reservoir: Taabo Lake (Côte d’Ivoire)

Taabo Lake is facing eutrophication process characterized by a permanent and continuous colonization of its water body by invasive aquatic macrophytes since 1990. Until now, there is limited knowledge of its ecological state. The purpose of this study is to examine the spatial distribution and structure of benthic macroinvertebrates in Taabo Lake. Benthic macroinvertebrates were sampled from July 2006 to June 2007 using an Ekman grab. Four sampling stations were selected on the area of the reservoir along a longitudinal gradient: Sahoua and Ahondo in the upper part; Taabo Cité and Taabo Village in the lower part. Overall, 29 taxa belonging to 17 families, 7 orders and 3 classes were recorded. A total of 4028 individuals were collected. Insecta (53.21%) were most represented, followed by Gasteropoda (36.15%) and Oligochaeta (10.64%). A better knowledge of the ecological traits of species and the identification of indicator taxa will permit to develop a Benthic Quality Index able to monitor the lakes and man-made reservoirs of Côte d’Ivoire.Keywords: Benthic macroinvertebrates, diversity, structure, lake, Côte d’Ivoire

Class-based multicast routing in interdomain scenarios

DiffServ-like domains bring new challenges to quality of service (QoS) multicast routing simply by shifting the focus from individual flows into classes of flows. Packets are marked at edge routers and receive differentiated treatment according to the class and not the flow that they belong to. DiffServ therefore became adverse to multicast, as packet replication inside the domain may require classification and remarking functions not present in core nodes. At the interdomain level, no doubt multicast QoS complexity is increased by the interleaving of DiffServ and non-Diffserv domains, making it more difficult to address QoS multicast in an end-to-end perspective. In today’s real interconnection world, classes of service have no meaning in certain links of a full interdomain path. While the problem is not new, as already pointed out, there are no real efforts to bring multicast back to a class-of-service domain without compromising its model of operation. In this article, we present an innovative multicast QoS routing strategy, clearly designed for the new class-of-service paradigm. The solution is based upon the construction of multiple trees, one per class of service available, while still allowing receivers to shift for source-specific trees in its own class of service. The strategy is presented in a full end-to-end perspective. Intradomain trees use differentiated routing paths thus helping traffic differentiation. Intradomain receivers are allowed to shift from shared trees into an adequate class-of-service source tree. At interdomain level, each class-of-service interdomain tree branch is accomplished by means of an improved path probing strategy enabling for QoS path establishment. This paper presents this new strategy, and associated protocols, for constructing several multicast and directed distribution trees, one per class of service, within each multicast group. This new strategy and associated protocols are then simulated using NS-2 platform. Simulation results are analyzed and compared with other multicast routing solutions, both at intra- and interdomain levels

What do γ\gamma-ray bursts look like?

There have been great and rapid progresses in the field of $\gamma$-ray bursts (denoted as GRBs) since BeppoSAX and other telescopes discovered their afterglows in 1997. Here, we will first give a brief review on the observational facts of GRBs and direct understanding from these facts, which lead to the standard fireball model. The dynamical evolution of the fireball is discussed, especially a generic model is proposed to describe the whole dynamical evolution of GRB remnant from highly radiative to adiabatic, and from ultra-relativistic to non-relativistic phase. Then, Various deviations from the standard model are discussed to give new information about GRBs and their environment. In order to relax the energy crisis, the beaming effects and their possible observational evidences are also discussed in GRB's radiations.Comment: 10 pages, Latex. Invited talk at the Pacific Rim Conference on Stellar Astrophysics, Hong Kong, China, Aug. 199

Premolis semirufa (Walker, 1856) Envenomation, Disease Affecting Rubber Tappers of the Amazon: Searching for Caterpillar-Bristles Toxic Components

Pararama, the popular name of the larval form of the moth Premolis semirufa inhabits rubber plantations in the Amazon region and the accidental contact of the skin with the caterpillar's bristles or cocoons results in immediate and intense heat, pain, edema, and itching. In many cases a chronic inflammatory reaction with immobilization of the joints occurs. The current study has evaluated the biological and immunochemical characteristics of the Pararama caterpillar bristles extract. Electrophoretic analysis showed the presence of several components, including a very intense 82 kDa band. This latter component was endowed with intense gelatinolytic activity, as observed in zymography assays. Further analysis revealed that the extract also contained hyaluronidase activity but is devoid of phospholipase A2 activity. In vivo assays, using mice, showed that the extract was not lethal, but caused significant edema and induced intense infiltration of inflammatory cells to the envenomation site. The extract also induced high specific antibody titers, but no autoantibodies were detected. The data obtained, so far, demonstrate the existence of a mixture of different enzymes in the bristles of Premolis semirufa caterpillar, which can act together in the generation and development of the clinical manifestations of the Pararama envenomation

Thyrotropin-releasing hormone (TRH) promotes wound re-epithelialisation in frog and human skin

There remains a critical need for new therapeutics that promote wound healing in patients suffering from chronic skin wounds. This is, in part, due to a shortage of simple, physiologically and clinically relevant test systems for investigating candidate agents. The skin of amphibians possesses a remarkable regenerative capacity, which remains insufficiently explored for clinical purposes. Combining comparative biology with a translational medicine approach, we report the development and application of a simple ex vivo frog (Xenopus tropicalis) skin organ culture system that permits exploration of the effects of amphibian skin-derived agents on re-epithelialisation in both frog and human skin. Using this amphibian model, we identify thyrotropin-releasing hormone (TRH) as a novel stimulant of epidermal regeneration. Moving to a complementary human ex vivo wounded skin assay, we demonstrate that the effects of TRH are conserved across the amphibian-mammalian divide: TRH stimulates wound closure and formation of neo-epidermis in organ-cultured human skin, accompanied by increased keratinocyte proliferation and wound healing-associated differentiation (cytokeratin 6 expression). Thus, TRH represents a novel, clinically relevant neuroendocrine wound repair promoter that deserves further exploration. These complementary frog and human skin ex vivo assays encourage a comparative biology approach in future wound healing research so as to facilitate the rapid identification and preclinical testing of novel, evolutionarily conserved, and clinically relevant wound healing promoters

Gauge symmetry and W-algebra in higher derivative systems

The problem of gauge symmetry in higher derivative Lagrangian systems is discussed from a Hamiltonian point of view. The number of independent gauge parameters is shown to be in general {\it{less}} than the number of independent primary first class constraints, thereby distinguishing it from conventional first order systems. Different models have been considered as illustrative examples. In particular we show a direct connection between the gauge symmetry and the W-algebra for the rigid relativistic particle.Comment: 1+22 pages, 1 figure, LaTeX, v2; title changed, considerably expanded version with new results, to appear in JHE