Obras ganadoras del Certamen Literario 12 de octubre, Día de la Hispanidad : 2016

Fuego en la mirada / Eladio Andreu Cámara. -- La película ; Silencios y nostalgias ; Fusiles de hojalata ; Noches de insomnio / Juan Antonio Nkono Ekaha Ndoh

An overview of anti-diabetic plants used in Gabon: Pharmacology and Toxicology

© 2017 Elsevier B.V. All rights reserved.Ethnopharmacological relevance: The management of diabetes mellitus management in African communities, especially in Gabon, is not well established as more than 60% of population rely on traditional treatments as primary healthcare. The aim of this review was to collect and present the scientific evidence for the use of medicinal plants that are in currect by Gabonese traditional healers to manage diabetes or hyperglycaemia based here on the pharmacological and toxicological profiles of plants with anti-diabetic activity. There are presented in order to promote their therapeutic value, ensure a safer use by population and provide some bases for further study on high potential plants reviewed. Materials and methods: Ethnobotanical studies were sourced using databases such as Online Wiley library, Pubmed, Google Scholar, PROTA, books and unpublished data including Ph.D. and Master thesis, African and Asian journals. Keywords including ‘Diabetes’ ‘Gabon’ ‘Toxicity’ ‘Constituents’ ‘hyperglycaemia’ were used. Results: A total of 69 plants currently used in Gabon with potential anti-diabetic activity have been identified in the literature, all of which have been used in in vivo or in vitro studies. Most of the plants have been studied in human or animal models for their ability to reduce blood glucose, stimulate insulin secretion or inhibit carbohydrates enzymes. Active substances have been identified in 12 out of 69 plants outlined in this review, these include Allium cepa and Tabernanthe iboga. Only eight plants have their active substances tested for anti-diabetic activity and are suitables for further investigation. Toxicological data is scarce and is dose-related to the functional parameters of major organs such as kidney and liver. Conclusion: An in-depth understanding on the pharmacology and toxicology of Gabonese anti-diabetic plants is lacking yet there is a great scope for new treatments. With further research, the use of Gabonese anti-diabetic plants is important to ensure the safety of the diabetic patients in Gabon.Peer reviewedFinal Accepted Versio

Rheology of magmas with bimodal crystal size and shape distributions: insights from analog experiments

Magmas in volcanic conduits commonly contain microlites in association with preexisting phenocrysts, as often indicated by volcanic rock textures. In this study, we present two different experiments that inves- tigate the flow behavior of these bidisperse systems. In the first experiments, rotational rheometric methods are used to determine the rheology of monodisperse and polydisperse suspensions consisting of smaller, prolate particles (microlites) and larger, equant particles (phenocrysts) in a bubble‐free Newtonian liquid (silicate melt). Our data show that increasing the relative proportion of prolate microlites to equant pheno- crysts in a magma at constant total particle content can increase the relative viscosity by up to three orders of magnitude. Consequently, the rheological effect of particles in magmas cannot be modeled by assuming a monodisperse population of particles. We propose a new model that uses interpolated parameters based on the relative proportions of small and large particles and produces a considerably improved fit to the data than earlier models. In a second series of experiments we investigate the textures produced by shearing bimodal suspensions in gradually solidifying epoxy resin in a concentric cylinder setup. The resulting textures show the prolate particles are aligned with the flow lines and spherical particles are found in well‐organized strings, with sphere‐depleted shear bands in high‐shear regions. These observations may explain the measured variation in the shear thinning and yield stress behavior with increasing solid fraction and particle aspect ratio. The implications for magma flow are discussed, and rheological results and tex- tural observations are compared with observations on natural samples

Biocompatibility assessment and antiproliferative activity of Detarium microcarpum Guill. and Perr. fruit pulp extracts.

The consumption of tropical fruits rich in chemopreventive compounds are required to prevent cells carcinogenesis and proliferation. This study was designed to assess de biocompatibility of Detarium microcarpum fruit extract on normal fibroblasts and its antiproliferative potentiality on human osteosarcoma MG-63 cells. Primary dermal fibroblasts and human osteosarcoma MG-63 cells were treated with different concentrations of hexane, chloroform, ethyl acetate and methanol extracts of D. microcarpum fruit pulp for 24h, 48h and 72h. The biocompatibility property of extracts on the normal fibroblasts and its antiproliferative activity on the human osteosarcoma cells were evaluated by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenytetrazolium bromide (MTT) assay. The biocompatibility study of D. microcarpum fruit pulp showed that the chloroform extract has exhibited the highest cytotoxic effect on normal fibroblasts followed by the ethyl acetate extract. Hexane extract wasn’t cytotoxic at concentrations of 125 and 250 µg/mL but caused more than 80 % of cell death at a concentration of 500 µg/mL. Methanol extract didn’t show a significant cytotoxic effect. Furthermore, chloroform and ethyl acetate extracts showed the best antiproliferative activity on osteosarcoma cells. A complete cell death was observed when osteosarcoma cells were treated with ethyl acetate extract at all concentrations while chloroform extract at concentrations of 250 and 500 µg/mL caused a complete cells death. Methanol extract exhibited any antiprolifarative activity. Chloroform and ethyl acetate extract of fruits pulp of D. microcapum are potent source of anticancer phytomolecules and have potential to be a promising anti-osteosarcoma extract

Determining baselines and trends of Eastern chimpanzees and forest elephants in a Central African protected area after civil strife

Protected areas are crucial to safeguard Sub-Saharan Africa’s extraordinary and abundant megafauna. In many of these areas, instability has derailed conservation efforts and impeded adequate wildlife monitoring. Discovered in 2004, Eastern chimpanzees are found in the Central Uele Basin in northern Democratic Republic of Congo (DRC) within the Bili-Uéré Protected Areas Complex (BUPAC), the largest contiguous protected area in the country. BUPAC is threatened by habitat destruction, mining, wild meat trade, and insecurity. BUPAC chimpanzees are part of the largest remaining continuous population of the species in Africa; they are also being behaviourally unique. Forest elephants were frequent in the 1960’s in the BUPAC but have declined significantly up to 2004 - 2007. We used line transects to estimate Eastern chimpanzee and forest elephant density in the BUPAC core area in 2016 and 2019 and compared these with the 2004-2007 surveys. A total of 37 and 137 two km long line transects were systematically placed in 5,841 km2 and 6,176 km2 survey areas in 2016 and 2019, respectively. We found that chimpanzee density did not change during the two survey periods but indicators for forest elephant density decreased eight-fold. Human activities were detected mainly along the core area periphery in both survey years, where they overlapped with centres of animal activity. The stable high density of chimpanzees is a positive outcome for the core BUPAC. However, despite being a conservation priority area that has received relatively intensified protection, declining forest elephant numbers are likely to reflect the high number of human conflict hotspots in vicinity as well as the increasing human population density around the core area. We propose by elevating the core area to National Park whilst strengthening on the ground enforcement and management structures as well as legal measures against poaching might ensure the long-term survival of such an important area in Africa

Multi-scale analysis and geodynamic interpretation of morphostructural data associated to the phanerozoic volcano-plutonism of Equatorial Africa (Cameroon line and neighboring regions)

De l’observation microscopique d’une lame mince à l’observation mégascopique d’une province volcano-plutonique par télédétection (SRTM, Landsat), ce travail s’intéresse aux méthodes de comptage, aux traitements statistique et fractale des tailles, formes, orientations et distributions spatiales ainsi qu’à l’interprétation pétrogénétique et/ou géodynamique de différents marqueurs géologiques (cristaux, linéaments, cônes volcaniques…) associés au volcano-plutonisme phanérozoïque d’Afrique équatoriale (Ligne du Cameroun et régions voisines).L’analyse à l’échelle microscopique de la distribution de taille de grains et des textures de roches volcaniques et mantelliques (laves et enclaves provenant de l’île de Bioko, golfe de Guinée) a permis de mettre en évidence l’importance d’une quantification objective des paramètres de taille et des relations entre les phases minérales. Après avoir appliqué et discuté les résultats obtenus par les méthodes dites de « distribution de tailles de grains » ou CSD (Crystal Size Distribution), les relations spatiales entre les cristaux et donc les textures ont été étudiées par analyse fractale classique puis grâce à l’entropie de Shannon, dont il s’agit de la première application 2D. La généralisation de ces méthodes de comptage à des objets géologiques de plus grande taille (linéaments, cônes volcaniques…) par le biais des images satellites (Landsat) et modèles numériques de terrain (MNT) issus des données SRTM, a permis d’aborder de manière objective, sur un nombre suffisant de mesures, la morphostructure de la région étudiée. L’ensemble des données morpho-structurales, soit 15.171 linéaments, 8.092 cônes volcaniques ou complexes annulaires, d’une vaste zone de plus de 2.700.000 km2 autour du golfe de Guinée, ont permis d’élaborer plusieurs modèles structuraux locaux qui, synthétisés dans une vue spatio-temporelle complète depuis le Carbonifère jusqu’à l’actuel, ont permis de redéfinir l’évolution géodynamique de la région.Cette zone mobile complexe, pincée entre le craton congolais et le craton ouest-africain, est caractérisée par un soubassement précambrien, réactivé lors de la mise en place des grands bassins sédimentaires et ensembles magmatiques phanérozoiques. Contrairement à un modèle unique, souvent invoqué, l’évolution géologique régionale se présente comme une suite de régimes transcurrents dextres se déplaçant spatialement autour des directions N80 au Jurassique, N120 au Crétacé et N30 du Paléogène à l’actuel. L’intégration des nombreuses données géochimiques et isotopiques de la littérature aux modèles géodynamiques de ce travail oblige à globaliser le magmatisme cénozoïque à l’échelle de l’Afrique équatoriale dans son ensemble qui se présente alors comme un « ensemble » magmatique cohérent.Doctorat en Sciencesinfo:eu-repo/semantics/nonPublishe

Economic growth and poverty in central Africa : an in-vestigation applied in CAEMC zone

L’impact de la croissance économique sur la pauvreté est un sujet d’intérêt politique majeur dans les pays en développement. Depuis que les institutions internationales ont admis l’importance de la croissance économique dans l’amélioration du bien-être des individus, celle-ci est devenue un élément fondamental des stratégies de lutte contre la pauvreté. Dans un tel contexte, l’attention accordée à la croissance économique dans la lutte contre la pauvreté est beaucoup débattue dans la littérature économique. Cette thèse procède à une analyse empirique de l’impact de la croissance économique sur la pauvreté, dans le cas des pays de la Communauté Economique et Monétaire de l’Afrique Centrale, sur la période 1981 à 2005. Dans une première partie, nous dressons un bilan théorique incontournable sur la pauvreté et sur les liens entre la croissance économique et la pauvreté. Nous présentons les stratégies de lutte contre la pauvreté et les faits stylisés de la pauvreté monétaire et non monétaire dans les pays de la CEMAC. Dans une deuxième partie, nous testons empiriquement l’impact de la croissance économique sur la pauvreté dans la CEMAC, en incluant l’Union Economique et Monétaire Ouest Africaine (UEMOA) en guise de comparaison. Nous évaluons empiriquement, le rôle des inégalités de revenus, de la corruption, et de la stabilité politique dans l’impact de la croissance économique sur la pauvreté dans les zones CEMAC et UEMOA.Les résultats suggèrent que la croissance économique est nécessaire pour réduire la pauvreté dans la CE-MAC et l’UEMOA. L’étude révèle que l’impact de la croissance économique sur la pauvreté est une fonction décroissante du degré d’inégalités. L’investigation montre également l’impact négatif d’une amélioration de la qualité des institutions sur la pauvreté. Les efforts de réduction de la pauvreté réalisés à travers la stimulation de la croissance économique devraient être accompagnés par des efforts de réduction des inégalités, de réduction de la corruption et un cadre politique sain.The impact of economic growth on poverty is a major political issue in developing countries. Since inter-national institutions have recognized the importance of economic growth in improving the well being of individuals, it has become a fundamental element of strategies that aim at reducing poverty. In this context, attention given to economic growth in the fight against poverty is much debated in the economic research. This thesis conducts an empirical analysis of the impact of economic growth on poverty, in the case of Central African Economic and Monetary Community (CAEMC) for the period 1981-2005. In a first section, we build a key theoretical assessment on poverty and on the links between economic growth and poverty. We present strategies for poverty reduction and the stylized facts of monetary and non-monetary poverty in the CAEMC countries. In a second part, we empirically test the impact of economic growth on poverty in the CAEMC by including the West African Economic and Monetary Union (WAEMU) for a comparison. We evaluate empirically the role of income inequality, corruption, and political stability in the impact of economic growth on poverty in CAEMC and WAEMU zone.The results suggest that economic growth is necessary to reduce poverty in CAEMC and WAEMU zone. The study reveals that the impact of economic growth on poverty is a decreasing function of inequality. The investigation also shows the positive impact of improving the quality of institutions on poverty re-duction. The policies aimed for poverty reduction through the stimulation of economic growth should be accompanied by simultaneous efforts to reduce inequality, corruption and a sound policy framework