1,622 research outputs found

    The Relationship Between Annual Rainfall Totals, Rainfall Onsets and Cocoa Yields in Ashanti Region of Ghana: A Reality or Farce?

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    Cocoa production in Ghana is basically rain fed and this makes it vulnerable to climate change and variability. This paper is part of an on-going research, which is investigating how changes in the climatic conditions in Ghana are affecting production levels of the cocoa industry. The study uses basically secondary data from the Ghana Cocoa Marketing Company and the Ghana Meteorological Service Weather stations at the Kwame Nkrumah University of Science and Technology, Kumasi and the Kumasi Airport between 1970 and 2010. Findings from the study reveal a decline in cocoa production of about 100,000 metric tonnes between 1970 and 1984 in the study region and increasing trend of rainfall totals. Notwithstanding, a direct correlation between rainfall totals and rainfall onsets; and cocoa yields could not be established. However, the study found a highly significant effect of climate variability in rainfall onset and annual rainfall totals on cocoa yield (p-value 0.01). The study thus concludes that climatic change and variability have influence on Ghana’s cocoa sector which calls for effective mitigation measures. Keywords: cocoa production, climate change and variabilit

    Internal displacement reactions in multicomponent oxides. Part I. Line compounds with narrow homogeneity range

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    As a model of an internal displacement reaction involving a ternary oxide "line" compound, the following reaction was studied at 1273 K as a function of time, t: Fe + NiTiO3 = "Ni" + "FeTiO3" Both polycrystalline and single-crystal materials were used as the starting NiTiO3 oxide. During the reaction, the Ni in the oxide compound is displaced by Fe and it precipitates as a γ-(Ni-Fe) alloy. The reaction preserves the starting ilmenite structure. The product oxide has a constant Ti concentration across the reaction zone, with variation in the concentration of Fe and Ni, consistent with ilmenite composition. In the case of single-crystal NiTiO3 as the starting oxide, the γ alloy has a "layered" structure and the layer separation is suggestive of Liesegang-type precipitation. In the case of polycrystalline NiTiO3 as the starting oxide, the alloy precipitates mainly along grain boundaries, with some particles inside the grains. A concentration gradient exists in the alloy across the reaction zone and the composition is >95 at. pct Ni at the reaction front. The parabolic rate constant for the reaction is kp = 1.3 × 10-12 m2 s-1 and is nearly the same for both single-crystal and polycrystalline oxides

    Internal displacement reactions in multicomponent oxides: Part II. Oxide solid solutions of wide composition range

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    As models of internal displacement reactions in oxide solid solutions, the following reactions were studied at 1273 K as a function of time: Fe + NixMg1-x)O = Ni + (FexMg1-x)O Fe + (Co0.5Mg0.5)O = Co + (Fe0.5Mg0.5)O In both reactions, Ni or Co in the starting oxide is displaced by Fe and the γ-(Ni-Fe) or (Co-Fe) alloy is precipitated. In the reaction zone, composition gradients develop in both product phases, viz., the oxide and the alloy precipitate. The Ni (or Co) concentration of the alloy precipitate increases towards the reaction front. In the product oxide, the "inert" Mg diffuses toward the reaction front along with the Fe, while the Ni (or Co) diffusion is in the opposite direction, towards the Fe/boundary. The shape of the composition profiles for Mg and Fe in the product oxide suggests that cross-coefficient terms in the generalized flux equations contribute significantly to the cation flux. The parabolic rate constants of reactions involving Fe/(NixMg1-x)O decrease by nearly four orders of magnitude when x decreases from 1 to 0.1

    Exploring local knowledge and perceptions on zoonoses among pastoralists in northern and eastern Tanzania

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    Background: Zoonoses account for the most commonly reported emerging and re-emerging infectious diseases in Sub-Saharan Africa. However, there is limited knowledge on how pastoral communities perceive zoonoses in relation to their livelihoods, culture and their wider ecology. This study was carried out to explore local knowledge and perceptions on zoonoses among pastoralists in Tanzania. Methodology and principal findings: This study involved pastoralists in Ngorongoro district in northern Tanzania and Kibaha and Bagamoyo districts in eastern Tanzania. Qualitative methods of focus group discussions, participatory epidemiology and interviews were used. A total of 223 people were involved in the study. Among the pastoralists, there was no specific term in their local language that describes zoonosis. Pastoralists from northern Tanzania possessed a higher understanding on the existence of a number of zoonoses than their eastern districts' counterparts. Understanding of zoonoses could be categorized into two broad groups: a local syndromic framework, whereby specific symptoms of a particular illness in humans concurred with symptoms in animals, and the biomedical framework, where a case definition is supported by diagnostic tests. Some pastoralists understand the possibility of some infections that could cross over to humans from animals but harm from these are generally tolerated and are not considered as threats. A number of social and cultural practices aimed at maintaining specific cultural functions including social cohesion and rites of passage involve animal products, which present zoonotic risk. Conclusions: These findings show how zoonoses are locally understood, and how epidemiology and biomedicine are shaping pastoralists perceptions to zoonoses. Evidence is needed to understand better the true burden and impact of zoonoses in these communities. More studies are needed that seek to clarify the common understanding of zoonoses that could be used to guide effective and locally relevant interventions. Such studies should consider in their approaches the pastoralists' wider social, cultural and economic set up

    Management of children with mild traumatic brain injury and intracranial hemorrhage

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    BACKGROUND: Traumatic brain injury (TBI) is a significant public health problem affecting tens of thousands of children each year, and an important subset of these patients sustains intracranial hemorrhage (ICH). The purpose of this study was to test the hypothesis that we could identify a subset of children with traumatic ICH who could be monitored on a general neurosurgery ward with a low risk of clinical deterioration. METHODS: We performed a retrospective review of pediatric patients 18 years or younger with mild TBI (Glasgow Coma Scale [GCS] score 14Y15) and traumatic ICH admitted to Saint Louis Children's Hospital between 2006 and 2011. We excluded patients with injuries unrelated to the TBI that would require intensive care unit (ICU) admission and those with penetrating intracranial injuries. RESULTS: We identified 118 patients meeting inclusion criteria. Repeat neuroimaging was obtained in 69 (58%) of 118 patients. Radiologic progression was noted in 6 (8.7%) of 69 patients, with a trend toward more frequent progression in patients with epidural hematoma (EDH) versus other ICH (3 [20%] of 15 vs. 3 [5.6%] of 54; p = 0.11). Of 118 patients, 8 (6.8%) experienced clinically important neurologic decline (CIND) and 6 (5.1%) required neurosurgical intervention. Both CIND and the need for neurosurgical intervention were significantly higher in patients with EDH (21% each) compared with those with other types of ICH (4% and 2%, respectively) (p = 0.02, p G 0.01). Based on these results, we developed a preliminary management framework to assist in determining which patients can be safely observed on a neurosurgery ward without an ICU admission. Specifically, those patients without EDH, intraventricular hemorrhage, coagulopathy, or concern for a high-risk neurosurgical lesion (e.g., arteriovenous malformation) may be safely observed on the ward. CONCLUSIONS: These results demonstrate that few children with mild TBI and ICH experience CIND and the preliminary framework we developed assists in identifying which patients can safely avoid ICU admission. This framework should be validated prospectively and externally. (J Trauma Acute Care Surg. 2014;76: 1089Y1095

    Family social support, community “social capital” and adolescents’ mental health and educational outcomes: a longitudinal study in England

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    Purpose To examine the associations between family social support, community “social capital” and mental health and educational outcomes. Methods The data come from the Longitudinal Study of Young People in England, a multi-stage stratified nationally representative random sample. Family social support (parental relationships, evening meal with family, parental surveillance) and community social capital (parental involvement at school, sociability, involvement in activities outside the home) were measured at baseline (age 13–14), using a variety of instruments. Mental health was measured at age 14–15 (GHQ-12). Educational achievement was measured at age 15–16 by achievement at the General Certificate of Secondary Education. Results After adjustments, good paternal (OR = 0.70, 95% CI 0.56–0.86) and maternal (OR = 0.65, 95% CI 0.53–0.81) relationships, high parental surveillance (OR = 0.81, 95% CI 0.69–0.94) and frequency of evening meal with family (6 or 7 times a week: OR = 0.77, 95% CI 0.61–0.96) were associated with lower odds of poor mental health. A good paternal relationship (OR = 1.27, 95% CI 1.06–1.51), high parental surveillance (OR = 1.37, 95% CI 1.20–1.58), high frequency of evening meal with family (OR = 1.64, 95% CI 1.33–2.03) high involvement in extra-curricular activities (OR = 2.57, 95% CI 2.11–3.13) and parental involvement at school (OR = 1.60, 95% CI 1.37–1.87) were associated with higher odds of reaching the educational benchmark. Participating in non-directed activities was associated with lower odds of reaching the benchmark (OR = 0.79, 95% CI 0.70–0.89). Conclusions Building social capital in deprived communities may be one way in which both mental health and educational outcomes could be improved. In particular, there is a need to focus on the family as a provider of support

    Metabolic acceleration and the evolution of human brain size and life history.

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    Humans are distinguished from the other living apes in having larger brains and an unusual life history that combines high reproductive output with slow childhood growth and exceptional longevity. This suite of derived traits suggests major changes in energy expenditure and allocation in the human lineage, but direct measures of human and ape metabolism are needed to compare evolved energy strategies among hominoids. Here we used doubly labelled water measurements of total energy expenditure (TEE; kcal day(-1)) in humans, chimpanzees, bonobos, gorillas and orangutans to test the hypothesis that the human lineage has experienced an acceleration in metabolic rate, providing energy for larger brains and faster reproduction without sacrificing maintenance and longevity. In multivariate regressions including body size and physical activity, human TEE exceeded that of chimpanzees and bonobos, gorillas and orangutans by approximately 400, 635 and 820 kcal day(-1), respectively, readily accommodating the cost of humans' greater brain size and reproductive output. Much of the increase in TEE is attributable to humans' greater basal metabolic rate (kcal day(-1)), indicating increased organ metabolic activity. Humans also had the greatest body fat percentage. An increased metabolic rate, along with changes in energy allocation, was crucial in the evolution of human brain size and life history
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