Lithology, age and structure of early proterozoic greenstone belts, West African shield

Lithologic and chemical data have been compiled for belts in the Proterozoic terrane. Available stratigraphic information from geologic maps of these areas indicate that a typical sequence is comprised of predominately mafic lava flows (basalt-andesite) at the base, which are overlain by felsic volcanic rocks including pyroclastic rocks and lavas. Lithostratigraphic data indicate the volcanic succession is 6-8 km thick. This is followed by 3-4 km of basaltic lava flows which are locally pillowed, the top of the unit is marked by a distinctive manganese formation (MF) consisting of Mn-Fe rich cherts up to 200 m thick. The youngest volcanic unit consists of mafic tuffs and breccia with a distinctive fragmental texture. Of about 100 chemical analyses reported calc-alkaline rocks constitute 55% and tholeiites 45%. Quartz-normative basalt constitutes 99% of the rock type in the tholeiitic suite. In the calc-alkaline suite, 9% of the analyses is basalt, 45% andesite and the rest is dacite and rhyodacite. The available data lead to the conclusion that the minimum age for the volcanic activity must be between 2200 and 2100 million years. It is significant that Archean ages have not been reported from any of the volcanic belts (1-10)

Geochemistry of volcanic rocks from the Wawa greenstone belt

The Wawa greenstone belt is located in the District of Algoma and extends east-northeast from Lake Superior to the western part of the Sudbury District in Ontario, Canada. Recent mapping by Attoh has shown that an unconformity at the base of the Dore' Formation and equivalent sedimentary rocks marks a significant stratigraphic break which can be traced throughout the volcanic belt. This break has been used to subdivide the volcanic-sedimentary into pre- and post-Dore' sequences. The pre-Dore' sequence includes at least two cycles of mafic-to-felsic volcanism, each capped by an iron-formation unit. The post-Dore' sequence includes an older mafic-to-felsic unit, which directly overlies sedimentary rocks correlated with the Dore' Formation, and a younger felsic breccia unit interpreted to have formed as debris flows from a felsic volcanic center. In the present study, samples of both the pre-and post-Dore' volcanic sequences were analyzed for major and trace elements, incuding rare earths (REE). This preliminary study is part of an ongoing program to assess the petrogenesis of the volcanic rocks of the Wawa greenstone belt

Rhyolitic components of the Michipicoten greenstone belt, Ontario: Evidence for late Archaen intracontinental rifts or convergent plate margins in the Canadian Shield?

Rhyolitic rocks often are the dominant felsic end member of the biomodal volcanic suites that characterize many late Archean greenstone belts of the Canadian Shield. The rhyolites primarily are pyroclastic flows (ash flow tuffs) emplaced following plinian eruptions, although deposits formed by laval flows and phreatomagmatic eruptions also are presented. Based both on measured tectono-stratigraphic sections and provenance studies of greenstone belt sedimentary sequences, the rhyolites are believed to have been equal in abundance to associated basaltic rocks. In many recent discussions of the tectonic setting of late Archean Canadian greenstone belts, rhyolites have been interpreted as products of intracontinental rifting . A study of the tectono-stratigraphic relationships, rock associations and chemical characteristics of the particularly ell-exposed late Archean rhyolites of the Michipicoten greenstone belt, suggests that convergent plate margin models are more appropriate

Performance Characteristics of Lactating Djallonké Ewes Fed Rice Straw Basal Diets Supplemented With Stylosanthes Hamata

A 7-week feed intake and growth performance study involving thirty lactating Djallonké ewes and their lambs was conducted. The ewes were randomly assigned to 3 dietary treatment groups resulting in 10 replications. The ewes were individually housed and offered 1000 g rice straw basal diet daily; Stylosanthes hamata given as a supplement at one of the 3 rates, which formed the treatments; i.e. 180 g/d [T180], 240 g/d[T240] or 360 g/d [T360]. Feed intake of the ewes and liveweight changes of the ewes and their lambs were recorded. Intake of rice straw was similar amongst the ewes on the different treatments (P>0.05). However, the ewes consumed more supplement as the amount offered increased resulting in a significant improvement in total feed intake as the supplement offered increased (P0.05) in the body weights of the ewes that could be attributable to treatment effects. The average daily gains (ADG) at day 49 for the lambs were, 47.5 [T180], 63.4 [T240] and 76 g [T360]. This result suggest that supplementation of ewes had a significant effect (

COVID-19 autopsy reports from the Ga-East Municipal and the 37 Military Hospitals in Accra, Ghana

Introduction: Since the declaration of COVID-19 by the World Health Organisation (WHO) as a global pandemic on 11th March 2020, the number of deaths continue to increase worldwide. Reports on its pathologic manifestations have been published with very few from the Sub-Saharan African region. This article reports autopsies on COVID-19 patients from the Ga-East and the 37 Military Hospitals to provide pathological evidence for better understanding of COVID-19 in Ghana.Methods: Under conditions required for carrying out autopsies on bodies infected with category three infectious agents, with few modifications, complete autopsies were performed on twenty patients with ante-mortem and/or postmortem RT -PCR confirmed positive COVID‑19 results, between April and June ,2020.Results: There were equal proportion of males and females. Thirteen (65%) of the patients were 55years or older with the same percentage (65%) having Type II diabetes and/or hypertension. The most significant pathological feature found at autopsy was diffuse alveolar damage. Seventy per cent (14/20) had associated thromboemboli in the lungs, kidneys and the heart. Forty per cent (6/15) of the patients that had negative results for COVID-19 by the nasopharyngeal swab test before death had positive results during postmortem using bronchopulmonary specimen. At autopsy all patients were identified to have pre-existing medical conditions.Conclusion: Diffuse alveolar damage was a key pathological feature of deaths caused by COVID-19 in all cases studied with hypertension and diabetes mellitus being major risk factors. Individuals without co-morbidities were less likely to die or suffer severe disease from SARS-CoV-

Railway bridge structural health monitoring and fault detection: state-of-the-art methods and future challenges

Railway importance in the transportation industry is increasing continuously, due to the growing demand of both passenger travel and transportation of goods. However, more than 35% of the 300,000 railway bridges across Europe are over 100-years old, and their reliability directly impacts the reliability of the railway network. This increased demand may lead to higher risk associated with their unexpected failures, resulting safety hazards to passengers and increased whole life cycle cost of the asset. Consequently, one of the most important aspects of evaluation of the reliability of the overall railway transport system is bridge structural health monitoring, which can monitor the health state of the bridge by allowing an early detection of failures. Therefore, a fast, safe and cost-effective recovery of the optimal health state of the bridge, where the levels of element degradation or failure are maintained efficiently, can be achieved. In this article, after an introduction to the desired features of structural health monitoring, a review of the most commonly adopted bridge fault detection methods is presented. Mainly, the analysis focuses on model-based finite element updating strategies, non-model-based (data-driven) fault detection methods, such as artificial neural network, and Bayesian belief network–based structural health monitoring methods. A comparative study, which aims to discuss and compare the performance of the reviewed types of structural health monitoring methods, is then presented by analysing a short-span steel structure of a railway bridge. Opportunities and future challenges of the fault detection methods of railway bridges are highlighted

VARYING LEVELS OF MAIZE BRAN IN DIETS ON THE PERFORMANCE AND CARCASS CHARACTERISTICS OF STARTER-GROWER PIGS

ABSTRACT A 17-week study was conducted to evaluate the effects of varying levels of maize bran in the diet on growth performance and carcass characteristics of starter-grower pigs. Nine 8-week-old Large White entire male pigs of initial weight of 14.4 kg were used in the study. The pigs were randomly allotted in equal numbers to three dietary treatments containing 0, 100 and 200 g maize bran kg-1 , with maize, fishmeal and soyabean meal as major ingredients. The diets were formulated to be isocaloric and isonitrogenous. The pigs had free access to feed and water. The concentration of maize bran in the diet had no significant effect on feed intake, weight gain, feed conversion efficiency and the various carcass parameters measured. There was, however, a decrease in the cost of feed and feed cost kg' 1 live weight gain with increasing levels of maize bran. The results indicate that maize bran may be included in pig starter diets up to 209 g kg-1 without causing adverse effects on pig performance

Pattern of pulmonary lesions in some wildlife rodents and duikers in Ghana

Respiratory disease has been presumed as a limiting factor in the domestication of some wild rodents; however, there is dearth of information on the pattern and burden of pulmonary lesions in these animals especially in West Africa where they are delicacies. A total of 96 rodents including 48 giant rats, 28 cane rats, 5 squirels and 15 duikers acquired from game meat market in Kumasi, Ghana were investigated for lung lesions. The lungs were observed macroscopically for distribution of consolidation and sections were further processed for microscopic evaluation using standard techniques. Results showed that 56 (58%) of lung samples had lesions with higher prevalence in giant rats than duiker. The young and male animals were observed to be more affected. Microscopic changes in the lung include pulmonary congestion, interstitial pneumonia, bronchopneumonia and atelectasis. The knowledge of the pattern of pneumonia in wildlife rodents and duikers calls for the need for a national surveillance on the nature of respiratory diseases of wildlife and it also may inform choices of conservational policies on these animals. .Keyword: Lung, Pneumonia, Rodents, Duiker, Ghana, Nigeri