Restauration de plages nues d’une brousse tachetée au Niger

Un essai de restauration de plages nues dfune brousse tachetee degradee du Parc National du W au sudouest du Niger a ete installe en 2007. Cet article etablit le bilan de cette restauration realisee par la plantation dfespeces locales dans des ouvrages antierosifs du type tranchees sylvopastorales. Dans la zonetemoin et dans la zone mise en defens par une cloture, le taux de survie des plants mis en place, leur croissance en hauteur et en diametre, la composition et la diversite floristique des herbacees ont ete suivis pendant trois ans (2007-2009). Lfeffet des ouvrages antierosifs sur lfhumidite du sol a ete evalue pendant lapremiere annee. Les analyses demontrent une amelioration nette des conditions ecologiques du site dfexperimentation, qui evolue progressivement vers lfetat dfune brousse tachetee, qui est lfecosysteme de reference. Lfamelioration de lfhumidite du sol induit des conditions beaucoup plus favorables pour la couverture vegetale. La richesse floristique dans la zone-temoin est passee en trois annees de 16 a 49, la diversite ƒ¿ de 2,1 a 4,42 et lfequitabilite de Pielou de 0,59 a 0,78. Dans la zone cloturee (mise en defens), la richesse floristique, la diversite ƒ¿ et lfequitabilite de Pielou sont respectivement passees en trois ans de 14 a 43, de 2,26 a 4,22 et de 0,53 a 0,79, ce qui traduit une amelioration progressive de la flore. Acacia senegal et Bauhinia rufescens ont enregistre les plus forts taux de survie et les plus importantes croissances en hauteur et en diametre. Les mortalites elevees des A. seyal et Ziziphus mauritiana sont vraisemblablement liees a la forte concentration de rongeurs que la presence dfune cloture ne gene guere. La pose couteuse dfune cloture nfest efficace que contre les grands mammiferes, ce qui se traduit toujourspar une croissance en diametre et en hauteur superieure pour la zone cloturee.Mots-cles : restauration ecologique, brousse tachetee, Acacia senegal, Acacia seyal, Bauhinia rufescens, Ziziphus mauritiana, ouvrage antierosif

Bethe lattice approach study of the mixed spin-1/2 and spin-7/2 Ising model in a longitudinal magnetic field

The magnetic properties of the mixed spin-1/2 and spin-7/2 Ising model with a crystal-field in a longitudinal magnetic field are investigated on the Bethe lattice using exact recursion relations. The ground-state phase diagram is constructed. The temperature-dependent one is displayed in the case of uniform crystal-field on the (k_BT/|J|, D/|J|) plane in the absence of the external constraint for lattice coordination numbers z=3,4,6. The order parameters and corresponding response functions as well as the internal energy are calculated and examined in detail in order to feature the real nature of phase boundaries and corresponding temperatures. The thermal variations of the average magnetization are classified according to the Néel nomenclature

Bethe approach study of the mixed spin-1/2 and spin-5/2 Ising system in the presence of an applied magnetic field

The mixed spin-1/2 and spin-5/2 Ising model is investigated on the Bethe lattice in the presence of a magnetic field h via the recursion relations method. A ground-state phase diagram is constructed which may be needful to explore important regions of the temperature phase diagrams of a model. The order-parameters, the corresponding response functions and internal energy are thoroughly investigated in order to typify the nature of the phase transition and to get the corresponding temperatures. So, in the absence of the magnetic field, the temperature phase diagrams are displayed in the case of an equal crystal-field on the (k_{B}T/|J|, D/|J|) plane when q=3,4,5 and 6. The model only exhibits the second-order phase transition for appropriate values of physical parameters of a model

The bimodal random crystal field and biquadratic exchange interaction effects for the spin-3/2 Ising model on the Bethe lattice

The phase transition properties of Blume-Emery-Griffiths (BEG) model for the spin-3/2 system are investigated on the Bethe lattice (BL) when the system is under the effect of both random crystal field (D) and biquadratic exchange interaction (K). These randomization effects are either turned on with probability 1 - p (q) or turned off with probability p (1 - q) for D and K, respectively. The phase diagrams are obtained on the (K/J, kT/J) and (D/J, kT/J) planes for given values of p and q when z = 3.0 corresponding to honeycomb lattice. Both attractive (K> 0) and repulsive (K +/- infinity for the phase diagrams on the (K/J, kT/J) planes

Phase diagrams and critical behaviours of the mixed spin-5/2 and spin-7/2 Ising system

We used mean-field theory based on the Bogoliubov inequality for the Gibbs free energy to examine the magnetic properties of a mixed spin-5/2 and spin-7/2 Blume-Capel ferrimagnetic system. The thermal behaviours of the system magnetization are classified according to the extended Neel nomenclature. The system exhibits compensation phenomena where a complete cancellation of sublattice magnetizations is observed below the critical temperature. Temperature-dependent phase diagrams are constructed for the case of unequal sublattice crystal field interactions. Under appropriate conditions, our calculations reveal first-order transitions in addition to second-order ones previously observed in Monte Carlo simulations

Aspects epidemiologiques et diagnostiques des traumatismes maxillo-faciaux au centre hospitalier universitaire departemental du Borgou, Benin

Objectif: Etudier les aspects épidémiologiques et diagnostiques des traumatismesmaxillo-faciaux au Centre Hospitalier Universitaire Départemental du Borgou à Parakou.Méthode: Il s’est agi d’une étude transversale descriptive allant du 1er Juin 2014 au 31 Mai 2017. Y ont été inclus tous les patients admis dans les services d’ORL et de Stomatologie du CHUD Borgou pour traumatisme maxillo-facial durant la période d’étude.Résultats: L’étude a porté sur 188 patients. La prédominance était masculine avec 83% de sujets de sexe masculin contre 17% de sexe féminin. L’âge moyen était de 30 ±11,4ans. Les élèves et étudiants étaient les plus concernés (23,4%) suivis des ouvriers (16,89%) et conducteurs (15 ,95%). Les accidents de la voie publique étaient la principale cause des traumatismes avec 156 cas (82,97%). Le dimanche a été le jour de la semaine où il y a eu le plus de traumatisés. Les véhicules à deux roues étaient impliqués dans 89,1% des accidents de la voie publique (AVP). Aucune victime d’AVP ne portait de casque ni de ceinture de sécurité. Les lésions des parties molles étaient les plus fréquentes (82,97%) suivies des lésions osseuses (47,87%). Parmi ces dernières, les fractures mandibulaires étaient les plus prédominantes avec 39 cas sur 90.Conclusion: Les traumatismes de la face sont relativement fréquents dans le service ORL-CCF du CHUD Borgou. Les accidents de la voie publique sont la principale cause de ces traumatismes. Les mesures de sécurité routière restent au premier plan de prévention.Mots clés: traumatisme, maxillo-facial, épidémiologie, fracture mandibulaireEnglish Title: Epidemiological and diagnostic aspects of maxillo-facial trauma in departmental teaching hospital of Borgou, BeninEnglish AbstractAim: to study the epidemiological and diagnostic aspect of maxillofacial trauma at the Departmental teaching hospital of BORGOU based in Parakou.Method: it was a descriptive and cross-sectional study covering three years period from 1st of June 2014 to May 31st 2017. We include all patients admitted at Departmental teaching hospital of Borgou with maxilla-facial trauma during our study.Result: a total of 188 patients were selected for this study. They were 83% men and 17% women. The mean age was 30+/-11.4. School students and those at university were dominating with 23.4% followed by workers at different levels 16.89% and drivers 15.95%. Road traffic accident was the main cause of trauma heading with 156 cases  (82.97%). The day of the week with the most cases of trauma was Sunday. Motors bike were the most involved in road traffic accident accounting with 89.1%. All victims from the trauma were not protected with helmet or seatbelt. Soft tissues were the most involved with 82.97% followed by bone fractures 47.87%. In the overall cases, mandibular fractures were the most predominant with 39 out of 90 cases.Conclusion: Maxillofacial trauma is relatively frequent in the ENT department of this hospital based in Parakou. Road traffic accident was the main cause of these injuries. Road traffic security remains the first line of trauma prevention.Keywords: Maxillofacial, trauma, epidemiology, mandibular fractur

Typology of Fermented Porridges and Socio-demographic Characteristics of Respondents in the Northern Part of Benin

Fermentation is an ancestral process and one of the most used economic methods in the preservation and transformation of cereal-based food raw materials. They are essentially rich in carbohydrates, but they can also be a source of micronutrients such as iron and are used in many traditional culinary preparations, in particular fermented porridges. The aim of this study is to identify the variability of fermented cereal-based porridges produced and consumed in northern Benin. Thus, 315 producers and consumers were randomly interviewed in nine localities of northern Benin. First, field surveys were carried out in the traditional areas of porridge production and consumption in the northern region of Benin in order to establish the consumption map of fermented porridges. Secondly, interviews and occasional conversations were used for sample collection as well as occasional interviews (individual survey). During our investigation, eight (koko, bobossou, gbangba, apkan, sagagnega, akloui, bita and fourra) porridge were reported. Corn, millet and sorghum are cereals that are used for proceeding those porridges. The interviewed people are predominantly (35.53%) between 18 and 25 years old of age followed by those aged between 25 and 31 years old (30.82%). Mostly (63.21%) women were interviewed with a sex ratio (M/F = 0.58) and involved in the production of traditional porridge. More than 36% of respondents had at least secondary education, 30.82% are uneducated, 22.64% have primary education and 10.06% had at least university level. A significant association was observed between the cereal used and the type of porridge (p<0.001). It can be seen that the marketing and consumption of different porridges is associated with different communes in northern Benin. The method of preserving these porridges and their processing differs from one producer to another or from one consumer to another. It also differs from one municipality to another