Assessment of agro-ecological influence on the seed quality of groundnut (Arachis hypogaea) in The Gambia

A survey was conducted to assess the quality of groundnut seed produced and stored under ambient environment across various agro-ecologies of The Gambia, with a view to understanding regions with comparative advantage for its production and storage. Seed production activities of 60 seed growers in 26 communities were collected using structured questionnaires, interviews and observations. The Global Positioning System (GPS) coordinates of the communities were geo-referenced to identify the geographical positioning of the production sites. Samples of the groundnut pods were taken from the seed stores, threshed and subjected to seed quality analysis. Descriptive analysis was used to categorize the seed sources, hectarage cultivated, while seed quality data were subjected to analysis of variance of Nested Design. Means of significant factors were separated using Duncan Multiple Range Test (DMRT) at 5% significant level. The study showed that groundnut seed production is better concentrated in regions with optimum and sustainable rainfall that will reduce abiotic stress during seed development like the Lower River Region, West Coast Region and Central River Region. Fleur-11 variety was identified as one of the most promising varieties for groundnut cultivation in The Gambia and Tropical Africa

Mafic explosive volcanism at Llaima Volcano: 3D x-ray microtomography reconstruction of pyroclasts to constrain shallow conduit processes

Mafic volcanic activity is dominated by effusive to mildly explosive eruptions. Plinian and ignimbrite-forming mafic eruptions, while rare, are also possible; however, the conditions that promote such explosivity are still being explored. Eruption style is determined by the ability of gas to escape as magma ascends, which tends to be easier in low-viscosity, mafic magmas. If magma permeability is sufficiently high to reduce bubble overpressure during ascent, volatiles may escape from the magma, inhibiting violent explosive activity. In contrast, if the permeability is sufficiently low to retain the gas phase within the magma during ascent, bubble overpressure may drive magma fragmentation. Rapid ascent may induce disequilibrium crystallization, increasing viscosity and affecting the bubble network with consequences for permeability, and hence, explosivity. To explore the conditions that promote strongly explosive mafic volcanism, we combine microlite textural analyses with synchrotron x-ray computed microtomography of 10 pyroclasts from the 12.6 ka mafic Curacautín Ignimbrite (Llaima Volcano, Chile). We quantify microlite crystal size distributions (CSD), microlite number densities, porosity, bubble interconnectivity, bubble number density, and geometrical properties of the porous media to investigate the role of magma degassing processes at mafic explosive eruptions. We use an analytical technique to estimate permeability and tortuosity by combing the Kozeny-Carman relationship, tortuosity factor, and pyroclast vesicle textures. The groundmass of our samples is composed of up to 44% plagioclase microlites, \u3e 85% of which are \u3c 10 µm in length. In addition, we identify two populations of vesicles in our samples: (1) a convoluted interconnected vesicle network produced by extensive coalescence of smaller vesicles (\u3e 99% of pore volume), and (2) a population of very small and completely isolated vesicles (\u3c 1% of porosity). Computed permeability ranges from 3.0 × 10−13 to 6.3 × 10−12 m2, which are lower than the similarly explosive mafic eruptions of Tarawera (1886; New Zealand) and Etna (112 BC; Italy). The combination of our CSDs, microlite number densities, and 3D vesicle textures evidence rapid ascent that induced high disequilibrium conditions, promoting rapid syn-eruptive crystallization of microlites within the shallow conduit. We interpret that microlite crystallization increased viscosity while simultaneously forcing bubbles to deform as they grew together, resulting in the permeable by highly tortuous network of vesicles. Using the bubble number densities for the isolated vesicles (0.1-3−3 × 104 bubbles per mm3), we obtain a minimum average decompression rate of 1.4 MPa/s. Despite the textural evidence that the Curacautín magma reached the percolation threshold, we propose that rapid ascent suppressed outgassing and increased bubble overpressures, leading to explosive fragmentation. Further, using the porosity and permeability of our samples, we estimated that a bubble overpressure \u3e 5 MPa could have been sufficient to fragment the Curacautín magma. Other mafic explosive eruptions report similar disequilibrium conditions induced by rapid ascent rate, implying that syn-eruptive disequilibrium conditions may control the explosivity of mafic eruptions more generally

From Manaus to Maputo: Toward a Public Health and Biodiversity Framework

The linkages between human health, biodiversity, ecosystems, and the life-supporting services that they provide are varied and complex. The traditional neglect of this nexus by policy-makers perpetuates threats posed to ecosystems with potentially critical impacts on global health. The Convention on Biological Diversity and the World Health Organization recently co-convened two regional workshops on these intricate but vital linkages. From discussions held with policy-makers and experts in the biodiversity and health sectors, spanning some 50 countries in Africa and the Americas, we derive a broad framework for the development of national and regional public health and biodiversity strategies relevant to strategic planning processes in the emerging post-2015 development context

Malaria vectors and transmission dynamics in coastal south-western Cameroon

BACKGROUND: Malaria is a major public health problem in Cameroon. Unlike in the southern forested areas where the epidemiology of malaria has been better studied prior to the implementation of control activities, little is known about the distribution and role of anophelines in malaria transmission in the coastal areas. METHODS: A 12-month longitudinal entomological survey was conducted in Tiko, Limbe and Idenau from August 2001 to July 2002. Mosquitoes captured indoors on human volunteers were identified morphologically. Species of the Anopheles gambiae complex were identified using the polymerase chain reaction (PCR). Mosquito infectivity was detected by the enzyme-linked immunosorbent assay and PCR. Malariometric indices (plasmodic index, gametocytic index, parasite species prevalence) were determined in three age groups (<5 yrs, 5–15 yrs, >15 yrs) and followed-up once every three months. RESULTS: In all, 2,773 malaria vectors comprising Anopheles gambiae (78.2%), Anopheles funestus (17.4%) and Anopheles nili (7.4%) were captured. Anopheles melas was not anthropophagic. Anopheles gambiae had the highest infection rates. There were 287, 160 and 149 infective bites/person/year in Tiko, Limbe and Idenau, respectively. Anopheles gambiae accounted for 72.7%, An. funestus for 23% and An. nili for 4.3% of the transmission. The prevalence of malaria parasitaemia was 41.5% in children <5 years of age, 31.5% in those 5–15 years and 10.5% in those >15 years, and Plasmodium falciparum was the predominant parasite species. CONCLUSION: Malaria transmission is perennial, rainfall dependent and An. melas does not contribute to transmission. These findings are important in the planning and implementation of malaria control activities in coastal Cameroon and West Africa

Control of superluminal transit through a heterogeneous medium

We consider pulse propagation through a two component composite medium (metal inclusions in a dielectric host) with or without cavity mirrors. We show that a very thin slab of such a medium, under conditions of localized plasmon resonance, can lead to significant superluminality with detectable levels of transmitted pulse. A cavity containing the heterogeneous medium is shown to lead to subluminal-to-superluminal transmission depending on the volume fraction of the metal inclusions. The predictions of phase time calculations are verified by explicit calculations of the transmitted pulse shapes. We also demonstrate the independence of the phase time on system width and the volume fraction under specific conditions.Comment: 21 Pages,5 Figures (Published in Journal of Modern Optics

Coating particles using liquids and foams based on viscous formulations with industrial mixers: Batch operation

Particle or powder coating with viscous liquids has been essential in industry for surface modification purposes to induce and enhance specific functionalities. This paper evaluates the performance of using foams (of different bubble diameters) versus liquids as a means of coating powder beds based on viscous liquid formulations. Coating with viscous liquids present numerous industrial challenges and therefore preparing foam equivalents can render the liquid component weak enough (through pre shearing to form the foam), to allow it to break up and coat particles under the shear forces exerted in a mixing device. In this study, two shear mixers are used; the first type consists of paddles in different configurations attached to a single rotating shaft, whilst the second type is a commercial twin screw mixer (TSM). The quality of coating achieved on the bulk powder bed using liquids and foams (stained with a dye) is assessed by image analysis to determine the homogeneity of the color distribution. In addition, scanning electron microscopy provides a tool to further investigate the coating quality of individual particles from the bulk product. The results show that large bubble (centimeter size) foams are much more effective at distributing within the fluidized powder bed compared to the starting viscous liquid and small bubble foams (sub-millimeter size). Furthermore, there is a maximum ratio of foam to powder beyond which agglomeration occurs and is insufficient to fully coat the particles. Coating of individual particles is achieved in the case of the TSM, whereas SEM proves that the single shaft paddle mixer crushes the particles and subsequently granulates them together to form granules of a size comparable to the size of coated particles seen after coating with the TSM

Phenolic content and heritability of resistance in four hybrid populations of Theobroma cacao L. after leaves inoculation with Phytophthora megakarya Bras. et Grif

Cocoa is cultivated in Cameroon for its broad beans. The commercialization of cocoa seeds constitutes a major source of income to farmers. Nevertheless, cacao black pod disease caused by Phytophthora megakarya is responsible of about 80% of cocoa production loss in Cameroon without any protection method. To assess the resistance of cocoa plants against this pathogen, necrotic lesions and phenolic content were conducted on 3 clones (SNK16, ICS40, Sca12) and their progenies (families F40, F12, F20 and F25) after leaves inoculation. The existence of strong hybrid vigour has been shown. All hybrid genotypes manifested a positive heterosis effect for this symptom suggesting the existence of hybrid vigour. Some hybrids like F40.6, F40.7, F40.8, F40.9, F40.10, F12.10, F12.15, F20.7, F20.10, F25.2, F25.5 and F25.7 were characterized by localized lesions. A negative correlation between the size of necrotic lesions and the total phenolic compound was demonstrated. Three genotypes of the F40 family (F40.8, F40.9 and F40.13), one of the F12 (F12.15) and two of the F25 (F25.2 and F25.8) had small lesions and high concentrations of phenols. These six genotypes can be considered as elite clones with high tolerance to P. megakarya. The values of the heritability of lesion size and the total phenolic content in offsprings don’t show the maternal effect.Keywords: Cocoa, Phytophthora megakarya, heterosis, heritability, necrosis, phenol

A snapshot of noncommunicable disease profiles and their prescription costs at ten primary healthcare facilities in the in the western half of the Cape Town metropole

Objectives: There has been a rapid increase in the prevalence of noncommunicable diseases globally. It is thought that this increase will have the greatest impact on developing countries, such as South Africa, where it will adversely affect quality of life and increase healthcare costs. This research was conducted to determine the disease profile and cost of treating patients at 10 facilities in the western half of the Cape Town Metropole. Design: An analytical, cross-sectional study was carried out in order to interpret the cost of the medication in relation to the patient disease profile. Setting and subjects: Data were collected from 10 facilities in the western half of the Cape Town Metropole over a three-month period. Outcome measure: The outcome measure was the disease profile of patients attending the facilities and the cost of prescriptions for these patients. Results: Most patient visits to the community health centres were to treat chronic diseases (82%). The disease profile of patients was as follows: 58.96% had hypertension, 19.67% diabetes, 12.14% asthma and chronic obstructive pulmonary disease, and 21.80% arthritis. It was found that 65% of patients with a chronic condition had co-morbidities. The cost of prescriptions was significantly higher (p-value < 0.001) for chronic conditions than for acute conditions. The number of comorbidities per patient also influenced the cost of the prescriptions. Conclusion: The results indicated that most of the adults attending public sector facilities in the western half of the Cape Town Metropole have chronic diseases and that the cost of treating these conditions is significantly greater than that of treating acute conditions. An integrated approach to the management of chronic diseases is important in low-resource settings for the efficient utilisation of limited resources