Geology of volcanogenic massive sulfide deposit near Meli, northwestern Tigray, northern Ethiopia

Results of a preliminary study conducted on the volcanogenic massive sulfide (VMS) deposit near Meli/Rahwa, northern Ethiopia are presented in the paper. The study area forms part of Neoproterozoic basement of northern Ethiopia and southern part of the Arabian Nubian Shield (ANS). Selected surface rock samples of different lithologies and core samples from five boreholes were analyzed for petrography and geochemistry. The area consists of matabasalt, meta-andesite and meta-rhyolite, meta-volcaniclastics, phyllite and post-tectonic granite. The rocks have experienced low grade metamorphic conditions. Base metal mineralization, VMS- type, is present and consists of pyrite, chalcopyrite, sphalerite and galena. Chloritization is the dominant alteration among others, and the ore body is associated with mafic to intermediate metavolcanic and metavolcaniclastic rocks and follows the same trend with the host rocks, striking north-south with subvertical dips. The mineralization is about 50-70m long, 15-20m thick and rich in copper and zinc (above 5%) and Au as a byproduct which is in minable amount in the VMS-related gossan. The deposit is related to bimodal volcanic condition and is produced in an island arc tectonic setting.Keywords: VMS, Base metals, Auriferous gossan, Meli/Rahwa, Tigray, Northern Ethiopia

Petrography and geochemistry of ferricrete near Shire, northern Ethiopia

A detailed petrographic and geochemical study was conducted on ferricrete (laterite) developed on Mesozoic (?) ferruginous sandstone near Shire, Tigray region, northern Ethiopia. 30 rock samples were analyzed for major and minor elements and studied for petrographic details. Ferruginous sandstone overlying the Neoproterozoic low grade basement rocks dominantly contains quartz followed by orthoclase feldspar and iron oxides/hydroxides as cement. Residual enrichment process has resulted in the development 2-3m thick ferricrete horizon and also sub-horizons: mottled, mixed nodular and psuedo-pisolitic. Mineralogy of the ferricrete includes limonite, goethite and hematite. Arid conditions and dehydration reactions seem to have produced hematite from goethite. The ore minerals show replacement, cavity and fracture filling, remobilization and colloform textures. Si>Al>Fe is the mobility pattern observed in the ferricrete horizon though presence of secondary quartz and kaolinite are also common. Development of ferricrete is related to the climatic condition that existed during Eocene and is comparable with similar deposits in Arabian Nubian Shield (ANS).Key words: Ferricrete, Laterite, Ferruginous sandstone, Shire, Tigray, Northern Ethiopia, AN

Implications of groundwater quality to corrosion problem and urban planning in Mekelle area, Northern Ethiopia

Surface and groundwater chemistry being an important factor in urban planning and infrastructure development, present paper tries to present the problems of corrosiveness due to groundwater chemistry in Mekelle city. Iron corrosion in distribution systems and engineering structures are common problems in many urban areas. Corrosiveness of groundwater at different localities in Mekelle and its environs has been evaluated on the basis of AAS-UV spectrophotometer-generated hydro-geochemical data. Corrosiveness of water was estimated by using corrosion indices like Larson Index, LI and Aggressive Index, AI and total dissolved solids, total carbonate hardness, chloride and sulphate data were evaluated to estimate aggressiveness of the water samples on iron pipes. Analyses of the results have shown that most of the samples from boreholes and hand dug wells compared to spring samples, are potentially aggressive. The result shows that 66.7% spring, 81.3% shallow hand dug wells and 81% borehole water samples have a Larson index (LI) above 0.5, a threshold of corrosiveness of water. This study highlights the basic characteristics of surface and groundwater chemistry and its potential hazard for corrosion of pipes, and provides a baseline information and awareness to the city planners for urban management

Adoption pathways for new agricultural technologies: An approach and an application to Vertisol management technology in Ethiopia

The literature on technology adoption distinguishes between diffusion (generally viewed as a dynamic process) and adoption (usually seen as static and specific to a point in time). Consistent with this, empirical studies on agricultural technology adoption generally divide a population into adopters and non-adopters, and analyse the reasons for adoption and non-adoption at a point in time, principally in terms of the socio-economic characteristics of the studied population. This study discusses the deficiencies of static approaches to technology adoption, particularly at the early stages of diffusion. It proposes a dynamic approach to technology adoption in which information gathering, learning and experience play pivotal roles. The characteristics of both the user and the technology are considered important in explaining adoption behaviour and the resultant pathway of adoption. The proposed approach has implications for the time frame and potential impact of new technology adoption

Identifying research questions for HIV, tuberculosis, tuberculosis-HIV, malaria, and neglected tropical diseases through the World Health Organization guideline development process: a retrospective analysis, 2008-2018.

OBJECTIVES: World Health Organization (WHO) guidelines for health programmes and healthcare delivery are the foundation of its technical leadership in public health and essential to decision-making globally. A key function of guideline development is to identify areas in which further evidence is needed because filling these gaps will lead to future improvements in population health. The objective of this study was to examine the knowledge gaps and research questions for addressing those gaps generated through the WHO guideline development process, with the goal of informing future strategies for improving and strengthening the guideline development process. STUDY DESIGN: We did a systematic, retrospective analysis of research questions identified in the published guidelines. METHODS: We analyzed guidelines published between January 1, 2008, and December 31, 2018, by the Communicable Diseases Cluster in five disease areas: tuberculosis (TB), HIV, malaria, TB-HIV, and neglected tropical diseases (NTDs). Research questions were extracted independently by two researchers. We analyzed the distribution of research questions by disease and by topic category and did a qualitative assessment of optimum practice for research question generation during the guideline development process. RESULTS: A total of 48 guidelines were included: 26 on HIV, 1 on malaria, 11 on TB, 5 on TB/HIV, and 5 on NTDs. Overall, 36 (75%) guidelines encompassed a total of 360 explicit research questions; the remainder did not contain specific research questions. The number of research questions that focused on TB was 49, TB/HIV was 38, HIV was 250, and NTDs was 23. The number of research questions that focused on diagnosis was 43 (11.9%) of 360, prevention was 62 (17.2%), treatment was 103 (28.6%), good practice was 12 (3.3%), service delivery was 86 (23.8%), and other areas was 54 (15%). Research questions were often not formulated in a specific or actionable way and were hard to identify in the guideline. Examples of good practice identified by the review team involved the generation of specific and narrowly defined research questions, with accompanying recommendations for appropriate study design. CONCLUSIONS: The WHO must strengthen its approach to identifying and presenting research questions during the guideline development process. Ensuring access to research questions is a key next step in adding value to the guideline development process

The Potential of Medical Abortion to Reduce Maternal Mortality in Africa: What Benefits for Tanzania and Ethiopia?

BACKGROUND: Unsafe abortion is estimated to account for 13% of maternal mortality globally. Medical abortion is a safe alternative. METHODS: By estimating mortality risks for unsafe and medical abortion and childbirth for Tanzania and Ethiopia, we modelled changes in maternal mortality that are achievable if unsafe abortion were replaced by medical abortion. We selected Ethiopia and Tanzania because of their high maternal mortality ratios (MMRatios) and contrasting situations regarding health care provision and abortion legislation. We focused on misoprostol-only regimens due to the drug's low cost and accessibility. We included the impact of medical abortion on women who would otherwise choose unsafe abortion and on women with unwanted/mistimed pregnancies who would otherwise carry to term. RESULTS: Thousands of lives could be saved each year in each country by implementing medical abortion using misoprostol (2122 in Tanzania and 2551 in Ethiopia assuming coverage equals family planning services levels: 56% for Tanzania, 31% for Ethiopia). Changes in MMRatios would be less pronounced because the intervention would also affect national birth rates. CONCLUSIONS: This is the first analysis of impact of medical abortion provision which takes into account additional potential users other than those currently using unsafe abortion. Thousands of women's lives could be saved, but this may not be reflected in as substantial changes in MMRatios because of medical abortion's demographic impact. Therefore policy makers must be aware of the inability of some traditional measures of maternal mortality to detect the real benefits offered by such an intervention