Nutrient Accumulation in Leaves and Soft Twigs of \u3ci\u3eMoringa oleifera\u3c/i\u3e Lam. at Different Growth Stages in Western Highland of Cameroon

Moringa oleifera belongs to the Moringaceae family and is considered to have its origin in the south of the Himalayan mountains. The species is being introduced into the highland zone of Cameroon. It is a tree which has many valuable properties and it is of great nutritional and scientific interest. The objective of this experiment was to evaluate nutrient composition in leaves and soft twigs of M. oleifera at different growth heights when grown in the Western Highland of Cameroon

Moabi (Baillonella toxisperma Pierre): Arbre à usage multiple de forêt dense humide du Cameroun

Le Moabi est un grand arbre de la forêt dense humide du Cameroun. Cet arbre à usages multiples, est recherché par l’industrie forestière pour la qualité de son bois et par les populations rurales pour ses produits autres que le bois tels l’écorce et les racines pour leurs importances médicinales, les fruits pour la fabrication d’huile. Ces formes d’exploitations concurrentielles, très souvent sans soucis de durabilité ont considérablement réduit les populations d’arbres, avec pour conséquence la rareté des produits dérivés. Face à cette forte pression anthropique qui s’exerce sur le Moabi dans le sud Cameroun, il a paru nécessaire d’effectuer une étude socioéconomique et écologique dans les villages à fortes activités d’exploitation. En effet, la compréhension des atouts socioculturels et des divers liens et usages que les ruraux tissent autour de cet arbre, l’estimation des stocks disponibles dans les terroirs villageois est un préalable impératif à l’élaboration des règles de gestion durable. Les enquêtes auprès des utilisateurs et les inventaires forestiers ont été réalisés dans sept villages. La distribution de cette espèce est estimée à 0,8 arbre/ha pour les individus d’un diamètre à 1,3 m supérieur à 10 cm. Cet arbre revêt une importance socioculturelle et incarne des pouvoirs divins indéniables pour 65% des ruraux. Les femmes représentent 56,5% des exploitants des produits forestiers non ligneux issus de cet arbre. Elles sont plus que les hommes, tributaires de l’exploitation des fruits et des écorces du Moabi. De ce fait, elles sont les principales victimes des conflits d’intérêts. Les écorces et le latex sont utilisés en pharmacopée. La production d’huile à partir des fruits peut générer jusque 1 050 000 Fcfa de rentrées financières dans le village Melondo. L’importance de ce gain incite à promouvoir l’extraction d’huile de Moabi dans le cadre de la diversification des sources de revenus et de la lutte contre la pauvreté.Mots clés: Moabi, usages multiples, gestion soutenue, communauté rurale, Camerou

Electromagnetic turbulent structures: A ubiquitous feature of the edge region of toroidal plasma configurations

Electromagnetic features of turbulent filaments, emerging from a turbulent plasma background, have been studied in four different magnetic configurations: the stellarator TJ-II, the Reversed Field Pinch RFX-mod, a device that can be operated also as a ohmic tokamak, and the Simple Magnetized Torus, TORPEX. By applying an analogous diagnostic concept in all cases, direct measurements of both field-aligned current density and vorticity were performed inside the filament. The inter-machine comparison reveals a clear dependence of the filament vorticity upon the local time-averaged E x B flow shear. Furthermore, a wide range of local beta was explored allowing concluding that this parameter plays a fundamental role in the appearance of filament electromagnetic features

Adiponectin levels and its relation with insulin secretion and insulin sensitivity in a group of sub-Saharan African women with polycystic ovary syndrome.

Low levels of adiponectin have been reported in Polycystic Ovary Syndrome (PCOS). In sub-Saharan Africa, little data are available on the topic. We aimed to investigate the levels of adiponectin and its relation with insulin secretion and insulin sensitivity in women with PCOS in Yaoundé, Cameroon. A comparative cross-sectional study was conducted in 32 women presenting PCOS and 32 controls matched for age and Body Mass Index. For each participant, adiponectin levels were measured. We estimated insulin sensitivity using Homeostasis model index (HOMA-IR) and insulin secretion with C-peptide levels. Women with PCOS had higher insulin secretion levels than controls (C-peptide: 4.98 ± 3.83 vs 3.25 ± 1.62 mUI/l; p = 0.02). Also, the HOMA-IR index was higher compared to that of women without PCOS (1.15 ± 0.90 vs 0.77 ± 0.38; p = 0.03) suggesting greater insulin resistance. The median [25th-75th percentile] values of adiponectin concentrations were similar between the two groups (22.68 [21.72-23.41] μg/ml vs 22.03 [21.40-22.93] μg/ml; p = 0.1). There was no association between insulin sensitivity and adiponectin levels in the PCOS group. PCOS is not associated with changes in adiponectin in a population of sub-Saharan African women. Further studies are needed to shed more light on this condition

Diagnostic performance and comparison of ultrasensitive and conventional rapid diagnostic test, thick blood smear and quantitative PCR for detection of low-density Plasmodium falciparum infections during a controlled human malaria infection study in Equatorial Guinea

BACKGROUND: Progress towards malaria elimination has stagnated, partly because infections persisting at low parasite densities comprise a large reservoir contributing to ongoing malaria transmission and are difficult to detect. This study compared the performance of an ultrasensitive rapid diagnostic test (uRDT) designed to detect low density infections to a conventional RDT (cRDT), expert microscopy using Giemsa-stained thick blood smears (TBS), and quantitative polymerase chain reaction (qPCR) during a controlled human malaria infection (CHMI) study conducted in malaria exposed adults (NCT03590340). METHODS: Blood samples were collected from healthy Equatoguineans aged 18-35 years beginning on day 8 after CHMI with 3.2 x 10(3) cryopreserved, infectious Plasmodium falciparum sporozoites (PfSPZ Challenge, strain NF54) administered by direct venous inoculation. qPCR (18s ribosomal DNA), uRDT (Alere Malaria Ag P.f.), cRDT [Carestart Malaria Pf/PAN (PfHRP2/pLDH)], and TBS were performed daily until the volunteer became TBS positive and treatment was administered. qPCR was the reference for the presence of Plasmodium falciparum parasites. RESULTS: 279 samples were collected from 24 participants; 123 were positive by qPCR. TBS detected 24/123 (19.5% sensitivity [95% CI 13.1-27.8%]), uRDT 21/123 (17.1% sensitivity [95% CI 11.1-25.1%]), cRDT 10/123 (8.1% sensitivity [95% CI 4.2-14.8%]); all were 100% specific and did not detect any positive samples not detected by qPCR. TBS and uRDT were more sensitive than cRDT (TBS vs. cRDT p = 0.015; uRDT vs. cRDT p = 0.053), detecting parasitaemias as low as 3.7 parasites/microL (p/microL) (TBS and uRDT) compared to 5.6 p/microL (cRDT) based on TBS density measurements. TBS, uRDT and cRDT did not detect any of the 70/123 samples positive by qPCR below 5.86 p/microL, the qPCR density corresponding to 3.7 p/microL by TBS. The median prepatent periods in days (ranges) were 14.5 (10-20), 18.0 (15-28), 18.0 (15-20) and 18.0 (16-24) for qPCR, TBS, uRDT and cRDT, respectively; qPCR detected parasitaemia significantly earlier (3.5 days) than the other tests. CONCLUSIONS: TBS and uRDT had similar sensitivities, both were more sensitive than cRDT, and neither matched qPCR for detecting low density parasitaemia. uRDT could be considered an alternative to TBS in selected applications, such as CHMI or field diagnosis, where qualitative, dichotomous results for malaria infection might be sufficient

Closing a gap in tropical forest biomass estimation : taking crown mass variation into account in pantropical allometries

Accurately monitoring tropical forest carbon stocks is a challenge that remains outstanding. Allometric models that consider tree diameter, height and wood density as predictors are currently used in most tropical forest carbon studies. In particular, a pantropical biomass model has been widely used for approximately a decade, and its most recent version will certainly constitute a reference model in the coming years. However, this reference model shows a systematic bias towards the largest trees. Because large trees are key drivers of forest carbon stocks and dynamics, understanding the origin and the consequences of this bias is of utmost concern. In this study, we compiled a unique tree mass data set of 673 trees destructively sampled in five tropical countries (101 trees > 100 cm in diameter) and an original data set of 130 forest plots (1 ha) from central Africa to quantify the prediction error of biomass allometric models at the individual and plot levels when explicitly taking crown mass variations into account or not doing so. We first showed that the proportion of crown to total tree aboveground biomass is highly variable among trees, ranging from 3 to 88 %. This proportion was constant on average for trees = 45 Mg. This increase coincided with a progressive deviation between the pantropical biomass model estimations and actual tree mass. Taking a crown mass proxy into account in a newly developed model consistently removed the bias observed for large trees (> 1 Mg) and reduced the range of plot- level error (in %) from [-23; 16] to [0; 10]. The disproportionally higher allocation of large trees to crown mass may thus explain the bias observed recently in the reference pantropical model. This bias leads to far- from- negligible, but often overlooked, systematic errors at the plot level and may be easily corrected by taking a crown mass proxy for the largest trees in a stand into account, thus suggesting that the accuracy of forest carbon estimates can be significantly improved at a minimal cost

Multifractal Spatial Patterns and Diversity in an Ecological Succession

We analyzed the relationship between biodiversity and spatial biomass heterogeneity along an ecological succession developed in the laboratory. Periphyton (attached microalgae) biomass spatial patterns at several successional stages were obtained using digital image analysis and at the same time we estimated the species composition and abundance. We show that the spatial pattern was self-similar and as the community developed in an homogeneous environment the pattern is self-organized. To characterize it we estimated the multifractal spectrum of generalized dimensions Dq. Using Dq we analyze the existence of cycles of heterogeneity during succession and the use of the information dimension D1 as an index of successional stage. We did not find cycles but the values of D1 showed an increasing trend as the succession developed and the biomass was higher. D1 was also negatively correlated with Shannon's diversity. Several studies have found this relationship in different ecosystems but here we prove that the community self-organizes and generates its own spatial heterogeneity influencing diversity. If this is confirmed with more experimental and theoretical evidence D1 could be used as an index, easily calculated from remote sensing data, to detect high or low diversity areas