Pediatric Cardiac Surgery In Eritrea: A retrospective analysis of 300 cardiac patients operated, 2002-2008.

A review of pediatric cardiac operations performed in the International Operation Center for Children in Asmara (IOCCA) between 2002 and 2008 was made. A total of 300 patients underwent corrective cardiac procedures during the time specified. Out of these, 273(91%) were patients suffering from congenital heart defects while the rest 27(9%) had acquired heart diseases. The female to male ratio was 1.4:1, and 157(52%) patients were under five years of age. 188(63%) of the procedures were open heart operations using the heart lung-machine and 112(37%) were closed heart operations without the cardiopulmonary bypass. The commonest operations performed were for PDA 103(34%), while the commonest open heart surgery was for VSD 74(25%). The mortality rate for patients operated was 7(2.3%) and the re-operation rate was 5(1.7%). The presence of an organized pediatric cardiac service in the country and its role in addressing different cardiac defects surgically and minimizing the cost of the procedures done elsewhere is emphasized

SOCIO-DEMOGRAPHIC FACTORS INFLUENCING THE USE OF MODERN CONTRACEPTION IN AN URBAN POPULATION IN SOUTH-WESTERN ETHIOPIA

ABSTRACT: A case-referent study to identify factors influencing the use and non-use of modern contraception was conducted in Jimma Town, a major urban center in south-western Ethiopia. Two hundred and fifty eight contraceptive users, selected from the registration books of three family planning clinics using simple random sampling techniques, were compared with age l:t-2 years) and neighbourhood (matched 258 contraceptive non-users.) The study revealed that birth place, duration of urban residence, religion, ethnic origin, number of rooms available for living and availability of radio, television and telephone do not have statistically significant association with contraceptive use (P > 0.05 in all cases). On the other hand, statistically significant association was noted between contraceptive use and marital status, educational status, occupational status, family monthly income and higher mean number of pregnancies, live births and living children. Taking a one to one ratio of male to female children of the sex composition of living children as a reference group, lack of male child is associated with a lower chance of contraceptive use (odds ratio = 0.497, p < 0.05). Among married women, higher educational and occupational status and monthly income of the spouse were also found to be associated with a higher chance of contraceptive use. In view of the several socio-demographic factors identified by the study, a multisectoral effort geared at urban disadvantaged women is recommended. [Ethiop. J. Health Dev. 1993;7(1):1-7

Electric vehicle possibilities using low power and light weight range extenders

Electric cars have the disadvantage of a limited range, and drivers may experience a range anxiety. This range anxiety can be solved by adding a range extender. But, the range extender should be light so as not to significantly increase the weight of the original vehicle. In urban areas with dense traffic (usually developing countries), the average speed around cities is typically lower than 50km/h. This means, the rolling resistance losses are more important than aerodynamic losses, and a weight reduction results in a bigger electrical range. Therefore, smaller and lighter range extenders are of much interest. The contribution of this paper is to indicate the possibility of range extenders with less than 25 kg with a capacity of 150 to 200 cc to suit a condition where weight counts. In this paper, the cost, environmental and grid impacts of going electric are also discussed. The effect of high altitude and driving style on the performance of an electric vehicle is assessed. The challenges and opportunities of vehicle electrification between countries with decarbonated power generation and fossil fuel dominated power generation are highlighted. Throughout the article, the case of Ethiopia is taken as an example

Hydrological characterization of watersheds in the Blue Nile Basin, Ethiopia

Thirty-two watersheds (31–4350 km2), in the Blue Nile Basin, Ethiopia, were hydrologically characterized with data from a study of water and land resources by the US Department of Interior, Bureau of Reclamation (USBR) published in 1964. The USBR document contains data on flow, topography, geology, soil type, and land use for the period 1959 to 1963. The aim of the study was to identify watershed variables best explaining the variation in the hydrological regime, with a special focus on low flows. Moreover, this study aimed to identify variables that may be susceptible to management policies for developing and securing water resources in dry periods. Principal Component Analysis (PCA) and Partial Least Square (PLS) were used to analyze the relationship between five hydrologic response variables (total flow, high flow, low flow, runoff coefficient, low flow index) and 30 potential explanatory watershed variables. The explanatory watershed variables were classified into three groups: land use, climate and topography as well as geology and soil type. Each of the three groups had almost equal influence on the variation in hydrologic variables (R2 values ranging from 0.3 to 0.4). Specific variables from within each of the three groups of explanatory variables were better in explaining the variation. Low flow and low flow index were positively correlated to land use types woodland, dense wet forest and savannah grassland, whereas grazing land and bush land were negatively correlated. We concluded that extra care for preserving low flow should be taken on tuffs/basalts which comprise 52% of the Blue Nile Basin. Land use management plans should recognize that woodland, dense wet forest and savannah grassland can promote higher low flows, while grazing land diminishes low flows

Climate, land use and vegetation trends: Implication of land use change and climate change on northwestern drylands of Ethiopia

Land use / land cover (LULC) change assessment is getting more consideration by global environmental change studies as land use change is exposing dryland environments for transitions and higher rates of resource depletion. The semiarid regions of northwestern Ethiopia are not different as land use transition is the major problem of the region. However, there is no satisfactory study to quantify the change process of the region up to now. Hence, spatiotemporal change analysis is vital for understanding and identification of major threats and solicit solutions for sustainable management of the ecosystem. LULC change studies focus on understanding the patterns, processes and dynamics of land use transitions and driving forces of change. The change processes in dryland ecosystems can be either seasonal, gradual or abrupt changes of random or systematic change processes that result in a pattern or permanent transition in land use. Identification of these processes of change and their type supports adoption of monitoring options and indicate possible measures to be taken to safeguard this dynamic ecosystem. This study examines the spatiotemporal patterns of LULC change, temporal trends in climate variables and the insights of the communities on change patterns of ecosystems. Landsat imagery, MODIS NDVI, CRU temperature, TAMSAT rainfall and socio-ecological field data were used in order to identify change processes. LULC transformation was monitored using support vector machine (SVM) algorithm. A cross-tabulation matrix assessment was implemented in order to assess the total change of land use categories based on net change and swap change. In addition, the pattern of change was identified based on expected gain and loss under a random process of gain and loss, respectively. Breaks For Additive Seasonal and Trend (BFAST) analysis was employed for determining the time, direction and magnitude of seasonal, abrupt and trend changes within the time series datasets. In addition, Man Kendall test statistic and Sen’s slope estimator were used for assessing long term trends on detrended time series data components. Distributed lag (DL) model was also adopted in order to determine the time lag response of vegetation to the current and past rainfall distribution. Over the study period of 1972- 2014, there is a significant change in LULC as evidenced by a significant increase in size of cropland of about 53% and a net loss of over 61% of woodland area. The period 2000-2014 has shown a sharp increase of cropland and a sharp decline of woodland areas. Proximate causes include agricultural expansion and excessive wood harvesting; and underlying causes of demographic factor, economic factors and policy contributed the most to an overuse of existing natural resources. In both the observed and expected proportion of random process of change and of systematic changes, woodland has shown the highest loss compared to other land use types. The observed transition and expected transition under random process of gain of woodland to cropland is 1.7%, implies that cropland systematically gains to replace woodland. The comparison of the difference between observed and expected loss under random process of loss also showed that when woodland loses cropland systematically replaces it. The assessment of magnitude and time of breakpoints on climate data and NDVI showed different results. Accordingly, NDVI analysis demonstrated the existence of breakpoints that are statistically significant on the seasonal and long term trends. There is a positive trend, but no breakpoints on the long term precipitation data during the study period. The maximum temperature also showed a positive trend with two breakpoints which are not statistically significant. On the other hand, there is no seasonal and trend breakpoints in minimum temperature, though there is an overall positive trend along the study period. The Man-Kendall test statistic for long term average Tmin and Tmax showed significant variation where as there is no significant trend within the long term rainfall distribution. The lag regression between NDVI and precipitation indicated a lag of up to forty days. This proves that the vegetation growth in this area is not primarily determined by the current precipitation rather with the previous forty days rainfall. The combined analysis showed declining vegetation productivity and a loss of vegetation cover that contributed for an easy movement of dust clouds during the dry period of the year. This affects the land condition of the region, resulting in long term degradation of the environmen

A Review on Biology and Management of Radopholus similis

The burrowing nematode (Radopholus similis) is an amphimictic species characterized by accentuated sexual dimorphism. Burrowing nematode has migratory endoparasitic habits and it develops and reproduces inside plant tissues of host roots. Fertilization is normally assumed to be bisexual, since females recovered from populations with males usually have sperm in their spermatheca, but reproduction by parthenogenesis does take place. The life cycle of the pathogen is completed in about 21 days at 25°C, and each female lays an average of four to five eggs each day for 2 weeks. This nematode burrows in the cortex of the root, destroying them and causing the formation of cavities then after eggs lay inside the cracks. R. similis of major economic importance and interactions with other pathogens enhance crop damage and yield loss. Phytosanitary measures are of prime importance in reducing the negative impact of plant-parasitic nematodes before they introduce. But once burrowing nematodes have become established in a field, the only option left is to try reducing their preplant density and further spread by the use of combination of different management methods such as crop rotation, cover crops, fallowing, removal of infested material, organic amendments, soil solarisation, hot water treatment, biological, host resistance and chemical methods. Generally knowing the biology of R. similis and its different management strategies contribute more to the reduction of the burrowing nematode and thus, sustainable banana production. Key words: Radopholus similis, amphimictic, parthenogenesis, sustainable, managemen

Effects of Natural Sand on the Mechanical Properties of High Density Polyethylene and Polypropylene

Composite materials were manufactured from two semi-crystalline thermoplastic polymers namely, high density polyethylene and polypropylene using Malaysian natural sand as filler. The chemical content and structure of the filler were studied using XRF and XRD respectively. Two different types of natural sand, Silica Sand (SS) and Beach Sand (BS) were used for comparison purpose. Test results from composite containing 10% by weight of each filler show that SS composite is much better than the BS composite. The effects of the natural SS content on the mechanical properties of the composite were investigated too. For the study, the composite was prepared in four different filler concentrations by weight of the polymer matrix, 0%, 5%, 10% and 15% using melt mixing process. A decrease in tensile strength of 10.3% and 9.3%, maximum elongation of 19.18% and 26.41% and a substantial increase in stiffness of around 42.9% and 5.8% were observed for the untreated HDPE/SS and PP/SS composites at 15wt% filler content respectively. Flexural test results for the polymer composites show a maximum modulus at 15wt% of 8.0% and an increasing trend of flexural strength for untreated HDPE/SS composite. On the other hand, for untreated PP/SS composite, a decrease in maximum deflection of 1.5% and an increment in flexural modulus of 19.7% and flexural strength of 3.5% have been observed at 15wt% filler content. The interfacial interaction between filler and matrix was studied by applying chemical treatment on the SS filler using silane coupling agent (SCA). The two types of SCA, γ-methacryloxypropyltrimethoxysilane (MTS) and vinyltriethoxysilane (VTES) were used for treatment. Samples prepared in the same manner as the untreated samples were tested. The HDPE/SS composites showed a tremendous increment in tensile strength and tensile modulus but a reduction in maximum elongation. Analysis of the treated PP composite showed a slight decrease in tensile strength and maximum deflection but a substantial increase in modulus of elasticity was observed as the percentage of filler was increased. Improvements in the flexural strength and flexural modulus were also recorded. A comparison of mechanical properties between 10wt% HDPE composites produced from MTS and VTES revealed that MTS is better than VTES. Morphology of the fractured surface from tensile test was analyzed by using Scanning Electron Microscopy (SEM). The microstructure revealed that there is weak interaction between the untreated filler and the matrix. On the other hand, a clear interfacial interaction was observed between the filler and polymer matrix in the case of treated sample. Thermal properties, mixing torque and rheology of the composite were also studied. It was found that the melting and crystalline temperatures show a slight increment of about 1.14% and 1.40% for 15wt% treated HDPE/SS composite. On the other hand, a decrease in melting and crystalline temperature of 0.74% and 0.04% for treated PP/SS composite respectively. The maximum torque required for mixing and rheological properties such as viscosity and shear rate were also increased with the filler content for the untreated composite sample. In the case of treated composite samples, the viscosity show a decrement compared to the untreated composite with maximum decrement of 35.6% was achieved at 15 wt%. Since this study is in a laboratory level, the maximum amount of filler is limited 15wt%. Applying a filler content of more than 15wt% can cause severe wear of the machine parts during mixing process. Key words: Natural sand

Hydrology and forests in the Blue Nile basin

Forest cover change is considered a major cause of water scarcity during the dry season in the Blue Nile River Basin of Ethiopia, which is part of the Nile River system. However, this is an over-simplification of the complex reality of forest and flow relationships, especially in the tropics. The objectives of this study were to explore the spatial relationship of land use and flow regime, detect temporal changes in the hydrological regime, determine changes in the forest cover, and summarize the results to define the relationship between forest cover and hydrological regime. Two broad approaches were used to address these aims: observational data analysis and community perception. Thirty-two watersheds were covered in the spatial study, and 45 years of data for a dozen of these watersheds were analyzed in the temporal study. Statistical methods were used to explore the spatial relationship of land use and flow, and both statistical and modeling methods were used to detect hydrological change over time. Remote sensing analysis was used to document forest cover changes. Natural grassland and woodland had a positive, while grazing land and open bush land had a negative correlation with low flow regimes at the spatial scale. There were no major temporal changes in the flow regime, or clear results to attribute land degradation or land use change to hydrological changes and specific changes within each watershed. The change related to forest cover were watershed specific, although there were general differences between southern and northern watersheds regarding the time of deforestation. The community perception indicated the relationship of forest cover change and flow regime was more complex than just deforestation causing loss of dry season flow. According to the elders, forest and flow relationships were watershed specific, even sub-watershed specific. The lack of a clear relationship between forest cover change and flow regime in the temporal dimension could be attributed to the scale of watersheds, uncertainty about the measurement of flow extremes, and the impact of variability in rainfall within the region. The watershed-specific nature of the relationship between forest and flow within the Basin, confirmed by the community perception, indicates forest hydrology studies should be tailored to watershed scale, or even sub-watershed scale i. e. hill-slope scale, and address the relevance of water availability at farm and river scale