Structure et composition floristiques des forêts denses sèches de la région des Monts Kouffé au Bénin

Objectif: L’objectif général de cette étude est la gestion rationnelle des écosystèmes forestiers en vue d’une conservation durable de la biodiversité floristique. Méthodologie et résultats: La méthodologie adoptée est basée sur les techniques de la phytosociologie. Ainsi, le groupement végétal des forêts denses sèches a été déterminé. Les forêts denses sèches sont généralement sur des plateaux. En leur sein, Anogeissus leiocarpa et Diospyros mespiliformis sont les espèces ligneuses végétales dominantes. Les valeurs moyennes de la richesse spécifiques, de l’indice de diversité de Shannom et de l’équitabilité de Piélou sont respectivement 7,5±2,38 espèces/placeaux, 1,98 ±0,45bits et 0,82±0,08. La densité moyenne des ligneux est de 379,25±158,61 individus/ha avec une surface terrière moyenne de 2,03±1,03 m²/ha. Conclusions et application des résultats: Les résultats ci-dessus ont permis de connaître l’importance floristique des forêts denses. Ainsi, l’administration forestière pourra suivre et planifier l’exploitation du bois d’oeuvre dans ces formations végétales. Mots Clés : Caractéristiques floristiques, phytoécologie, forêts denses sèches, région des Monts Kouffé, Béni

Probing Short Range Nucleon Correlations in High Energy Hard Quasielastic pd Reactions

We show that the strong dependence of the amplitude for $NN$ hard scattering on the collision energy can be used to magnify the effects of short range nucleon correlations in quasielastic $pd$ scattering. Under specific kinematical conditions the effect of initial and final state interactions can be accounted for by rescaling the cross section calculated within the plane wave impulse approximation. The feasibility to investigate the role of relativistic effects in the deuteron wave function is demonstrated by comparing the predictions of different formalisms. Binding effects due to short range correlations in deuteron are discussed as well.Comment: 18 pages (LaTex) + 10 postscript figs (available on request

Electronic structure of superconducting graphite intercalate compounds: The role of the interlayer state

Although not an intrinsic superconductor, it has been long--known that, when intercalated with certain dopants, graphite is capable of exhibiting superconductivity. Of the family of graphite--based materials which are known to superconduct, perhaps the most well--studied are the alkali metal--graphite intercalation compounds (GIC) and, of these, the most easily fabricated is the C${}_8$K system which exhibits a transition temperature $\bm{T_c\simeq 0.14}$K. By increasing the alkali metal concentration (through high pressure fabrication techniques), the transition temperature has been shown to increase to as much as $\bm 5$K in C${}_2$Na. Lately, in an important recent development, Weller \emph{et al.} have shown that, at ambient conditions, the intercalated compounds \cyb and \cca exhibit superconductivity with transition temperatures $\bm{T_c\simeq 6.5}$K and $\bm{11.5}$K respectively, in excess of that presently reported for other graphite--based compounds. We explore the architecture of the states near the Fermi level and identify characteristics of the electronic band structure generic to GICs. As expected, we find that charge transfer from the intercalant atoms to the graphene sheets results in the occupation of the $\bm\pi$--bands. Yet, remarkably, in all those -- and only those -- compounds that superconduct, we find that an interlayer state, which is well separated from the carbon sheets, also becomes occupied. We show that the energy of the interlayer band is controlled by a combination of its occupancy and the separation between the carbon layers.Comment: 4 Figures. Please see accompanying experimental manuscript "Superconductivity in the Intercalated Graphite Compounds C6Yb and C6Ca" by Weller et a

SCHOOL CLIMATE AND ORGANIZATIONAL LEARNING CAPABILITIES AMONG TEACHERS IN POLANCO DISTRICT II: Education

The purpose of this study was to evaluate the school climate and organizational learning capacities of teachers in the Polanco II District during the calendar year 2020. In this study, a quantitative descriptive-correlational research design was used. Data from 154 instructors in the Polanco II District are collected using frequency counting and percent, weighted mean, standard deviation, Mann-Whitney U test, Kruskal-Wallis test, and Spearman Rank-Order Correlation. The findings revealed that the perceived degree of school climate was very high. All indicators had standard deviations less than 3.00, indicating that the mean responses were closely clustered. Organizational learning capability was assessed to be quite capable. According to the data, teachers' assessed school climate and organizational learning capability are highly associated and significantly related to organizational learning capability

Three-dimensional water impact at normal incidence to a blunt structure

The three-dimensional (3D) water impact onto a blunt structure with a spreading rectangular contact region is studied. The structure is mounted on a flat rigid plane with the impermeable curved surface of the structure perpendicular to the plane. Before impact, the water region is a rectangular domain of finite thickness bounded from below by the rigid plane and above by the flat free surface. The front free surface of the water region is vertical, representing the front of an advancing steep wave. The water region is initially advancing towards the structure at a constant uniform speed. We are concerned with the slamming loads acting on the surface of the structure during the initial stage of water impact. Air, gravity and surface tension are neglected. The problem is analysed by using some ideas of pressure-impulse theory, but including the time-dependence of the wetted area of the structure. The flow caused by the impact is 3D and incompressible. The distribution of the pressure-impulse (the time-integral of pressure) over the surface of the structure is analysed and compared with the distributions provided by strip theories. The total impulse exerted on the structure during the impact stage is evaluated and compared with numerical and experimental predictions. An example calculation is presented of water impact onto a vertical rigid cylinder. Three-dimensional effects on the slamming loads are of main concern in this study

Vulnérabilité des troupeaux transhumants aux mutations climatiques : analyse des perceptions et adaptations locales dans le bassin de la Sota à Malanville

L’élevage bovin occupe une place importante parmi les activités des populations du Nord-Est du Bénin. Cette activité est très vulnérable aux mutations climatiques dans le bassin de la Sota à Malanville situé à l’extrême Nord-Est du Bénin. La présente recherche vise, d’une part, à appréhender, les perceptions des agro-éleveurs et des éleveurs sur les mutations climatiques et à analyser, d’autre part, leurs stratégies pour y faire face. Les données sur les perceptions et les stratégies d’adaptation ont été collectées au moyen d’enquêtes faites par entretiens, focus groupes et questionnaires dans cinq (5) villages choisis de manière aléatoire. Le calcul du taux moyen de réponse et l’analyse en composantes principales ont été utilisés pour analyser ces données. Les résultats montrent une grande similitude des manifestations des mutations climatiques perçues par les agro-éleveurs et éleveurs. Les manifestations les plus citées sont: la hausse des températures (citée par 99,16% des agro-éleveurs et 100% des éleveurs), les poches de sécheresse prolongée (citée par 67,5% des agro-éleveurs et 91,66% des éleveurs), les vents forts et violents (citée par 70% des agro-éleveurs et 87,08% des éleveurs). Pour ce qui concerne les effets des mutations climatiques, les agro-éleveurs et les éleveurs en perçoivent respectivement 9 et 11.Pour les premiers, les effets les plus marquants sont l’assèchement des points d’eau (80%), l’amenuisement du disponible fourrager (71,42%), la contamination et le comblement des points d’eau (65%). Pour les seconds, ce sont: l’amenuisement du disponible fourrager (96,66%), la contamination et le comblement des points d’eau (92,50%), l’assèchement précoce des points d'eau (91,50%), l’affaiblissement des animaux (57,50%), l’amaigrissement des animaux (56,66%). En réponse à cette instabilité du climat et ses effets, les agro-éleveurs et les éleveurs ont développé des stratégies dont les principales (communes aux deux groupes socio-professionnels) sont : le respect des campagnes de vaccination (citée par 85% des agro-éleveurs et 97,50% des éleveurs), l’abreuvement au fleuve ou à la rivière (citée par 37,50% des agro-éleveurs et 55% des éleveurs), la mobilité spatiale (citée par 59,50% des agro-éleveurs et 55% des éleveurs). Les résultats du test de Mann Whitney indiquent une différence significative de perception au seuil de 5% pour les effets, manifestations et stratégies communs aux deux groupes socioprofessionnelsMots-clés: mutations climatiques, perceptions et stratégies d’adaptation, agro-éleveurs et éleveurs, vulnérabilité, bassin de la Sota, Malanville. Vulnerability of transhumant herds to the climatic mutations: analysis of the perceptions and local adaptations in the watershed of Sota at MalanvilleThe bovine breeding occupies a significant place among the activities of the populations of the North-East of the Benin. This activity is very vulnerable to the climatic mutations in the watershed of Sota at Malanville located at the far North-East of Benin. This research aims, on the one hand, to understand the perceptions of the agro-pastoralists and the stockbreeders on the climatic mutations and, on the other hand, to analyze the strategies implemented by them to face there. The data on perceptions and the strategies of adaptation of the agro-pastoralists and the stockbreeders were collected using interviews, focus groups and questionnaires in five (5) villages randomly selected. The calculation of the response rate and the analysis in principal components were used to analyze the data. The results show a great similarity of the manifestations of the climatic mutations perceived by the agro-pastoralists and the stockbreeders. The most quoted manifestations are: the temperatures increase (quoted by 99.16% of the agro-pastoralists and 100% of the stockbreeders), prolonged dry spells (quoted by 67.5% of the agro-pastoralists and 91.66% of the stockbreeders), strong and violent winds (quoted by 70% of the agro-pastoralists and 87.08% of the stockbreeders). Concerning the effects of climatic mutations, the agro-pastoralists and the stockbreeders perceive respectively 9 and 11.For the firsts, the most significant effects are the drying up of the water points (80%), the dwindling of available forage (71.42%), the contamination and the filling of the water points (65%). For the seconds the main effects are: the dwindling of available forage (96.66%), the contamination and the filling of the water points (92.50%), premature drying up of the water points (91.50%), the weakening of the animals (57.50%), the slimming of the animals (56,66%). In response to this instability of the climate and its effects, the agro-pastoralists and the stockbreeders developed strategies. The main common strategies are: the respect of the vaccination campaigns (quoted by 85% of the agro-pastoralists and 97.50% of the stockbreeders), watering at the river (quoted by 37.50% of the agro-pastoralists and 55% of the stockbreeders) and spatial mobility (quoted by 59.50% of the agro-pastoralists and 55% of the stockbreeders). The results of the Mann Whitney test indicated a significant difference in perception threshold of 5% for effects, manifestations and strategies common to both socio professional groups.Keywords: climatic mutations, perceptions and strategies of adaptation, agro-pastoralists, stockbreeders, vulnerability, watershed of Sota, Malanville

Using Sat solvers for synchronization issues in partial deterministic automata

We approach the task of computing a carefully synchronizing word of minimum length for a given partial deterministic automaton, encoding the problem as an instance of SAT and invoking a SAT solver. Our experimental results demonstrate that this approach gives satisfactory results for automata with up to 100 states even if very modest computational resources are used.Comment: 15 pages, 3 figure