Essais d'adaptation de production massive de juvéniles de Clarias gariepinus en conditions rurales

Adaptive Trials for Intensive Clarias gariepinus fingerling to Rural Conditions. Artificial reproduction and fingerling production of the African catfish Clarias gariepinus (Burchell 1822) have been tested under less controlled conditions to adapt the intensive technology used by Aquafarm (Tihange, Belgium) to rural conditions present in developing countries. The main aim was to compare the efficiency of ovaprim a synthesised hormone with catfish pituitary extracts. Fecundity and quality of eggs (egg weight) were not significantly different. Incubation results on water hyacinth and on mosquito mesh frames were compared to those obtained in Zoug jars; the latter showed a higher hatching rate (67%) than water hyacinth (39%) and mosquito mesh frames (44%). Larvae were stocked at different stocking rates in ponds (T1: 800 larvae.m-3 and T2: 1600 larvae. m-3 ) and in tanks (T3: 3200 larvae.m-3 et T4: 6400 larvae.m-3). After a 50-day nursing period, no significant difference (P> 0.05) was observed for specific growth rate (SGR) and survival rate, but better SGR were observed in ponds (18.34%.d-1) than in tanks (16.81%.d-1). In general, production was slightly higher in tanks than in ponds being related to a higher stocking density. Significantly higher harvests were obtained from tanks with higher stocking densities but the sizes of the larvae were very heterogeneous. In such case, it is recommended to grade the larvae at 6 or 7 days intervals using different mesh sizes (from 3 to 5 mm). These less intensive rearing conditions gave nevertheless good fingerling productions

LABORATORY INVESTIGATION OF SEAT SUSPENSION PERFORMANCE DURING VIBRATION TESTING

ABSTRACT Mining injury statistics show that a significant number of back, neck, and head injuries are linked to exposure from vehicle vibration. Use of a suspension seat is a common way to isolate the vehicle operator from the adverse effects of vibration exposure. Thus, researchers at the National Institute for Occupational Safety and Health 1 -Pittsburgh Research Laboratory (NIOSH -PRL) performed laboratory studies on four passive and two semi-active seat suspension designs. These are typical of seat suspensions commonly found on large off-road heavy surface mining, construction and agricultural vehicles as either replacement or original equipment manufacturer (OEM) systems. One included a pneumatic (air bladder) spring mechanism. The fifth and sixth suspensions were a NIOSH magnetorheological (MR) semiactive damper design based on the pneumatic (air bladder) and one of the coil spring suspensions above. These suspensions were modified with a commercially available MR damper substituted for the OEM damper. These six seat suspension systems were tested and analyzed, for vertical vibration only, using the ISO 5007 Standard Results for suspensions 1 through 3 showed frequencies of isolation from 2.1 to 3.0 Hz using the 40-kg (88-lb) mass and from 1.65 Hz to 1.8 Hz using the 80-kg (176-lb) mass. Suspension #4, in tests with only the 80-kg (176-lb) mass, showed an isolation frequency of 3.7 Hz. With the MR damper added to seat suspension #4, the peak transmissibility was lowered from 1.3 to 0.95 and showed a corresponding downward shift in frequency from 2.25 Hz to 1.4 Hz. In fact, the results for suspension #5 (the MR damper added to seat suspension #4), using test #3 conditions of the programmed control algorithm, showed isolation (attenuation of transmitted vibration) throughout the test frequency range from 1.0 to 6.0 Hz. INTRODUCTION NIOSH mining vehicle seat and vibration research is dedicated to reducing the risk of injuries to the back, neck, or head for vehicle operators through improved mining vehicle seat designs. In this regard, injury statistics for mobile mining equipment operators from the Mine Safety and Health Administration (MSHA) showed incidences of exposure to whole-body vibration (WBV) and mechanical shock (vehicle jarring or jolting). These injuries can be described as acute and chronic musculoskeletal disorders affecting the back, neck, and head. For example at surface mining operations, Wiehagen et al. One way to lessen the adverse effects of vehicle vibration to the operator is through the use of a seat suspension system. Suspension seats are included in most industrial vehicles and are passive in nature in that they consist of a damper and some form of a spring. Moreover, during operation, these vehicles are subjected to significant energy in the 2 to 4 Hz region where conventional seats tend to amplify vertical vibration. A common method used to reduce vehicle operators' exposure to vehicle vibration is to design the natural frequency of the seat suspension so that it is considerably lower than the typical operating frequency generated by the vehicle. However, a large decrease in seat stiffness ("softer" or lower spring rate) is required to achieve this. Considering equatio

Clinical Practice Guidelines for Childbearing Female Candidates for Bariatric Surgery, Pregnancy, and Post-partum Management After Bariatric Surgery

Emerging evidence suggests that bariatric surgery improves pregnancy outcomes of women with obesity by reducing the rates of gestational diabetes, pregnancy-induced hypertension, and macrosomia. However, it is associated with an increased risk of a small-for-gestational-age fetus and prematurity. Based on the work of a multidisciplinary task force, we propose clinical practice recommendations for pregnancy management following bariatric surgery. They are derived from a comprehensive review of the literature, existing guidelines, and expert opinion covering the preferred type of surgery for women of childbearing age, timing between surgery and pregnancy, contraception, systematic nutritional support and management of nutritional deficiencies, screening and management of gestational diabetes, weight gain during pregnancy, gastric banding management, surgical emergencies, obstetrical management, and specific care in the postpartum period and for newborns

The “resort effect”: Can tourist islands act as refuges for coral reef species?

There is global consensus that marine protected areas offer a plethora of benefits to the biodiversity within and around them. Nevertheless, many organisms threatened by human impacts also find shelter in unexpected or informally protected places. For coral reef organisms, refuges can be tourist resorts implementing local environment-friendly bottom-up management strategies. We used the coral reef ecosystem as a model to test whether such practices have positive effects on the biodiversity associated with de facto protected areas.USAI

Conservation genetics of the annual hemiparasitic plant Melampyrum sylvaticum (Orobanchaceae) in the UK and Scandinavia

Melampyrum sylvaticum is an endangered annual hemiparasitic plant that is found in only 19 small and isolated populations in the United Kingdom (UK). To evaluate the genetic consequences of this patchy distribution we compared levels of diversity, inbreeding and differentiation from ten populations from the UK with eight relatively large populations from Sweden and Norway where the species is more continuously distributed. We demonstrate that in both the UK and Scandinavia, the species is highly inbreeding (global F IS = 0.899). Levels of population differentiation were high (F’ST = 0.892) and significantly higher amongst UK populations (F’ST = 0.949) than Scandinavian populations (F’ST = 0.762; P < 0.01). The isolated populations in the UK have, on average, lower genetic diversity (allelic richness, proportion of loci that are polymorphic, gene diversity) than Scandinavian populations, and this diversity difference is associated with the smaller census size and population area of UK populations. From a conservation perspective, the naturally inbreeding nature of the species may buffer the species against immediate effects of inbreeding depression, but the markedly lower levels of genetic diversity in UK populations may represent a genetic constraint to evolutionary change. In addition, the high levels of population differentiation suggest that gene flow among populations will not be effective at replenishing lost variation. We thus recommend supporting in situ conservation management with ex situ populations and human-mediated seed dispersal among selected populations in the UK

The Enigma of Soil Animal Species Diversity Revisited: The Role of Small-Scale Heterogeneity

Peer reviewedPublisher PD

Technique de production intensive du poisson chat africain, Clarias gariepinus

Intensive Production of African Catfish, Clarias gariepinus. The African catfish, Clarias gariepinus, is well appreciated in Africa and reaches high prices on the town markets (2 - 3 Euro/kg). Although it is raised since 1974 and its production is increasing in Europe, Asia and Latin America, the African production is on standby. The intensive production systems (biomass: 10 - 400 kg/m3, production: 1 - 4 kg/m3/j) in recirculated systems recently developed in Europe (family farms: 200 - 250 t/year) are profitable when the selling price on the farm reach 1,2 Euro/kg. This kind of model could be adapted by the African fish farmers to their local conditions and finally contributed to an important development of fish culture in Africa