Variabilités bioclimatiques et distribution spatiale des herbacées fourragères dans le Moyen-Bénin (Afrique de l’Ouest)

Les menaces continues des parcours de transhumance sont dues aux variabilités des facteurs climatiques accentuées par les activités anthropiques. La dégradation de ces écosystèmes en zone soudanoguinéenne a des conséquences sur la disponibilité de fourrage pour l’alimentation du bétail. L’étude sur la compréhension de la distribution géographique des herbacées fourragères les plus appétées au cours des périodes de transhumance de bétail dans le Moyen-Bénin, a été possible grâce à la modélisation à partir de l’algorithme de Maximum Entropie. Le présent article se propose d’une part de déterminer les étendues des habitats potentiels présents et de prédire la distribution future de ces herbacées fourragères dans le Moyen- Bénin. A cet effet, 988 points d’observations dont (184) pour Andropogon chinensis, (350) pour Andropogon gayanus, (127) pour Andropogon schirensis et (327) pour Andropogon tectorum ont été utilisés pour la modélisation. Le modèle MIROC avec deux scénarii d’émission de Gaz à Effet de Serre dont l’un pessimiste RCP 2.6, et l’autre optimiste RCP 8.5 a contribué à faire tourner 19 variables bioclimatiques et 3 variables environnementales. Les résultats obtenus ont permis de déterminer les habitats potentiels des différentes herbacées fourragères et d’établir une corrélation entre leur distribution et l’évolution des paramètres environnementaux et bioclimatiques.Mots clés : Distribution géographique, variabilités climatiques, herbacées fourragères, Moyen-Bénin

Modelling tree fodder ecological niches in variable climatic conditions in Middle Benin (West Africa)

La conservation des ligneux fourragers est un bon moyen de gestion rationnelle de la biodiversité des parcours naturels et de durabilité des modes d’existence des éleveurs transhumants. La maîtrise de leur distribution géographique s’avère indispensable pour comprendre leur domaine de tolérance vis-à-vis des facteurs environnementaux et prédire leur dynamique. La modélisation de la niche écologique des ligneux fourragers dans le Moyen-Bénin a permis de construire une fonction de paramètres environnementaux qui prédit la probabilité de présence de ces ligneux dans les parcours de transhumance de bétail. Elle aborde de façon spécifique la distribution potentielle des ligneux fourragers et leur prédiction à l’horizon 2050. Le Modèle climatique MIROC a été utilisé à cet effet avec deux scénarii climatiques du Groupe Intergouvernemental d’évolution du Climat (GIEC) à savoir : 2.6 et 8.5 à l’horizon 2050. Sur les dix-neuf variables bioclimatiques et trois paramètres environnementaux testés, cinq variables bioclimatiques et deux paramètres environnementaux ayant le plus contribué au modèle ont été retenus. Trois zones de distribution potentielle des différents ligneux fourragers : très peu favorables (0,1 < P < 0,4), moyennement favorables (0,4 < P < 0,7), et très favorables (P < 0,7) ont été distinguées aussi bien dans le présent que dans le futur.Tree fodder conservation is a great way for better management of rangelands’ biodiversity and for sustaining pastoralists’ livelihoods. Mastering their geographical distribution is essential to understand to what extent they are tolerant to environmental factors and to predict their dynamics. In Middle Benin tree fodder ecological niche was modelled as a function of environmental parameters that predict tree fodder probability of occurrence in the grazing areas used by pastoralists during transhumance. The model specifically addresses tree fodder potential distribution and its probability till 2050. Climate Model MIROC was used for this purpose with two climate scenarios from the Intergovernmental Panel on Climate Change (IPCC), namely: 2.6 and 8.5. Over the nineteen bioclimatic variables and three environmental parameters tested, five bioclimatic variables and two environmental parameters that contributed most to the model were retained. Three areas of potential distribution of different tree fodder: very lowly favourable (0.1 < P < 0.4), moderately positive (0.4 < P < 0.7) and very favourable areas (P < 0.7), were distinguished both in the present and in the future (2050)

Reliability analysis of solar-gas hybrid receivers for Central Tower Plants

A novel Solar-Gas Hybrid Receiver (SGHR) that combines the function of a solar receiver and a gas boiler in a single device is presented. This concept requires less equipment and maintenance compared to the Solar Gas Hybrid(SGH) concept, in which the boiler and the solar receiver (SR) are independent devices. The economic benefit is attributed to the increased sharing of infrastructures. Additionally, it has less thermal stress, cycles and shocks, which reduce the failure risk. However, the additional benefit in the reliability of these receivers has not been analyzed so far. In this work, a mathematical model of SGHR is presented. It determines the stress in steady state which is used to estimate the allowable transient stress in order to achieve the required 30 years life design. The results show that the SGHR is exposed to lower thermal stress due to much better temperature distribution. Moreover the higher …info:eu-repo/semantics/publishedVersio

Traitement chirurgical par plaque à compression des fractures de Galeazzi chez l’adulte: À propos de 28 cas

La fracture de Galeazzi associe une fracture diaphysaire du radius ou des deux os de l'avant bras à une luxation de l'articulation radio ulnairedistale. Décrite en 1934, sa fréquence varie chez l'adulte entre 2,7% et 6,8% de l'ensemble des fractures de l'avant bras. Le traitement admis defaçon consensuel chez l'adulte est chirurgical reposant sur une ostéosynthèse stable par une plaque vissée de compression dynamique associée ou non à un embrochage de la radio ulnaire distale. Nous rapportons dans notre étude les résultats cliniques de 28 patients colligés au service de traumatologie et orthopédie A du CHU Hassan II de Fès sur une période de 06 ans. L'âge moyen de nos patients était de 30 ans avecprédominance masculine de 90%; tous nos patients ont présenté un traumatisme de poignet lors d'un accident de sport. Le côté droit était atteint dans 75 % des cas. Le bilan radiologique objectiva une fracture diaphysaire du raduis associée à une luxation radio ulnaire distale; nous avons adopté la classification de de Mansat. Le traitement a consisté en une synthèse par une plaque vissée dynamique associée à un   embrochage transversal chez six patients qui ont présenté une instabilité de la radio ulnaire distale. L'immobilisation par attelle plâtrée postérieure BABP était de mise. Après un recul de 36 mois, nos résultats ont été très satisfaisants suivant le score de Mestdagh, avec bonne récupération de la mobilité du poignet et reprise de toute activité sportive

Horizontal Gene Transfer Regulation in Bacteria as a “Spandrel” of DNA Repair Mechanisms

Horizontal gene transfer (HGT) is recognized as the major force for bacterial genome evolution. Yet, numerous questions remain about the transferred genes, their function, quantity and frequency. The extent to which genetic transformation by exogenous DNA has occurred over evolutionary time was initially addressed by an in silico approach using the complete genome sequence of the Ralstonia solanacearum GMI1000 strain. Methods based on phylogenetic reconstruction of prokaryote homologous genes families detected 151 genes (13.3%) of foreign origin in the R. solanacearum genome and tentatively identified their bacterial origin. These putative transfers were analyzed in comparison to experimental transformation tests involving 18 different genomic DNA positions in the genome as sites for homologous or homeologous recombination. Significant transformation frequency differences were observed among these positions tested regardless of the overall genomic divergence of the R. solanacearum strains tested as recipients. The genomic positions containing the putative exogenous DNA were not systematically transformed at the highest frequencies. The two genomic “hot spots”, which contain recA and mutS genes, exhibited transformation frequencies from 2 to more than 4 orders of magnitude higher than positions associated with other genes depending on the recipient strain. These results support the notion that the bacterial cell is equipped with active mechanisms to modulate acquisition of new DNA in different genomic positions. Bio-informatics study correlated recombination “hot-spots” to the presence of Chi-like signature sequences with which recombination might be preferentially initiated. The fundamental role of HGT is certainly not limited to the critical impact that the very rare foreign genes acquired mainly by chance can have on the bacterial adaptation potential. The frequency to which HGT with homologous and homeologous DNA happens in the environment might have led the bacteria to hijack DNA repair mechanisms in order to generate genetic diversity without losing too much genomic stability

Reliability analysis of Solar-Gas Hybrid Receivers for central tower plants

A novel Solar-Gas Hybrid Receiver (SGHR) that combines the function of a solar receiver and a gas boiler in a single device is presented. This concept requires less equipment and maintenance compared to the Solar Gas Hybrid (SGH) concept, in which the boiler and the solar receiver (SR) are independent devices. The economic benefit is attributed to the increased sharing of infrastructures. Additionally, it has less thermal stress, cycles and shocks, which reduce the failure risk. However, the additional benefit in the reliability of these receivers has not been analyzed so far. In this work, a mathematical model of SGHR is presented. It determines the stress in steady state which is used to estimate the allowable transient stress in order to achieve the required 30 years life design. The results show that the SGHR is exposed to lower thermal stress due to much better temperature distribution. Moreover the higher absorber heat flux of SGHR is translated in a higher mechanical stress with could jeopardizes the durability. However the reduced number of cycles and the lower thermal stress of a SGHR allows higher transient stresses than the conventional tube type solar receiver, which lead to more reliable and efficient designs

Real-Time DSP-Free 100Gbit/s/λ PAM-4 Fiber Access Link using EML and Direct Detection

A 100 Gbit/s/ λ PAM-4 fiber link with an optical budget of 30 dB and 20 km fiber reach is achieved in real time experiments. This is compliant with class A (20 dB) point to point (PtP) applications as mobile fronthaul for example, and with class N1 (29 dB) point to multipoint (PtMP) for residential market. We used an integrated externally modulated laser, an analog pre-equalizer, an optical booster amplifier and/or non-filtered preamplifier and direct detection without any digital signal processing (whether real-time or offline)

Integrating temperature-dependent life table data into Insect Life Cycle Model for predicting the potential distribution of <em>Scapsipedus icipe</em> Hugel &amp; Tanga

Scapsipedus icipe Hugel and Tanga (Orthoptera: Gryllidae) is a newly described edible cricket species. Although, there is substantial interest in mass production of S. icipe for human food and animal feed, no information exists on the impact of temperature on their bionomics. Temperature-dependent development, survival, reproductive and life table parameters of S. icipe was generated and integrated into advanced Insect Life Cycle Modeling software to describe relative S. icipe population increase and spatial spread based on nine constant temperature conditions. We examined model predictions and implications for S. icipe potential distribution in Africa under current and future climate. These regions where entomophagy is widely practiced have distinctly different climates. Our results showed that S. icipe eggs were unable to hatch at 10 and 40°C, while emerged nymphs failed to complete development at 15°C. The developmental time of S. icipe was observed to decrease with increased in temperature. The lowest developmental threshold temperatures estimated using linear regressions was 14.3, 12.67 and 19.12°C and the thermal constants for development were 185.2, 1111.1- and 40.7-degree days (DD) for egg, nymph and pre-adult stages, respectively. The highest total fecundity (3416 individuals/female/generation), intrinsic rate of natural increase (0.075 days), net reproductive rate (1330.8 female/female/generation) and shortest doubling time (9.2 days) was recorded at 30°C. The regions predicted to be suitable by the model suggest that S. icipe is tolerant to a wider range of climatic conditions. Our findings provide for the first-time important information on the impact of temperature on the biology, establishment and spread of S. icipe across the Africa continent. The prospect of edible S. icipe production to become a new sector in food and feed industry is discussed