415 research outputs found
State Fragility, Regime Survival and Spoilers in South Sudan
This paper draws on the notion of state fragility in three dimensions – Authority failures, Service delivery failures and Legitimacy failures as developed by Stewart and Brown. Using Stewart and Brown’s analysis of fragile states, the authors examine how recent events in South Sudan push the country into being the most fragile state. In furthering this three-dimensional approach, we attempt two important questions. How has South Sudan succumbed to fragility since attaining independence? Who influences peace in the country? The authors grapple with these questions by investigating events in South Sudan from the period of signing the Comprehensive Peace Agreement (CPA 1 2005), independence in 2011, signing CPA 2 in 2015 up to present. The paper singles out the desire for regime survival as the major cause of fragility. The authors further argue that insecurity and instability are exacerbated by spoiling behaviour of certain powers and individuals, whose activities undermine state authority and creates disorder
Forecast of Future Aviation Fuels. Part 1: Scenarios
A preliminary set of scenarios is described for depicting the air transport industry as it grows and changes, up to the year 2025. This provides the background for predicting the needs for future aviation fuels to meet the requirements of the industry as new basic sources, such as oil shale and coal, which are utilized to supplement petroleum. Five scenarios are written to encompass a range of futures from a serious resource-constrained economy to a continuous and optimistic economic growth. A unique feature is the choice of one immediate range scenario which is based on a serious interruption of economic growth occasioned by an energy shortfall. This is presumed to occur due to lags in starting a synfuels program
Physico-chemical Assessment of Drinking Water with Special Emphasis on Fluoride Concentration in the Akatsi-North district in the Volta Region of Ghana
The present article has emerged from investigation into the water situation in three villages in the Akatsi-North district, to test the extent to which expectations of the United Nations (UN) Resolution 64/292 stipulations have been met in this part of the Volta region of Ghana. Thirty-six water samples were collected from twelve different boreholes (three villages) in the Akatsi-North district and analysed for their physico-chemical parameters using appropriate certified and acceptable international standards. Most of the physico-chemical parameters measured were within WHO guidelines for quality drinking water. The results showed that groundwater from two of the three villages were soft with pH ranging from 6.3 to 7.9. Cadmium concentrations for the groundwater samples analysed were above the critical value of 0.003 mg/L. Lead and nickel were not detected while the concentrationsof phosphate (0.50 – 0.53 mg/L) and copper (0.32-0.37 mg/L ) provided basis for the incidence of gastrointestinal and/or purgative effects experienced by most inhabitants prior to questionnaire analysis. Iron concentrations recorded for the three villages were within the ranges of 0.005-0.130mg/L, 0.13-0.23 mg/L, and 0.85-1.41 mg/L for Ave Xevi, Ave Afiadenyigba and Ave Etekorfe respectively. Mean concentrations of Ca2+, Mg2+, CO32-, and total alkalinity obtained for the three villages were (112, 168, 517) mg/L, (68, 112, 208) mg/L, (49, 80, 256) mg/L, and (220, 260, 380) mg/L respectively. Fluoride concentrations were low (0.07 mg/L and 0.16mg/L) for two of the three villages which may be responsible for the incidence of tooth decay among the inhabitants
Wildlife Species as Potential Sources of Human Exposure to Parasitic Pathogens in Accra, Ghana
Handling and consumption of wildlife species pose risks of exposure to the infective stages of parasitic pathogens and disease transmission. This study assessed protozoan and helminth infections in some wildlife species commonly consumed as meat in Accra, Ghana. Using Zinc Sulphate centrifugal flotation and microscopic techniques, seven protozoan species (Entamoeba sp., Giardia sp., Iodamoeba sp., Cryptosporidium sp., Balantidium sp., Endolimax sp. and Eimeria sp.) and 11 genera of intestinal helminths including Haemonchus, Trichostrongylus, Ascaris, Monieza, Schistosoma and Trichuris were identified. Kruskal-Wallis tests showed significant difference in intensity of protozoan [χ2(3) = 11.59; p = 0.009] and helminth [χ2(3) = 31.41; p < 0.0001] infections among the four groups of wildlife species. For protozoans, the differences were observed between the mean cyst and oocyst (Cryptosporidium sp.) intensities of Maxwell’s Duiker and Bushbuck (U = 5, p = 0.006) as well as Grasscutter and Bushbuck (U = 3, p = 0.004). However, the differences in mean helminth egg intensities were observed between Grasscutter and Maxwell’s Duiker (U = 6, p < 0.0001), Grasscutter and Bushbuck (U = 16, p < 0.0001) as well as Grasscutter and Royal Antelope (U = 4, p < 0.0001). The results highlight the need for awareness of the risks of parasitic diseases as a prerequisite for their effective prevention
Using GIS for spatial exploratory analysis of borehole data: a firsthand approach towards groundwater development
Groundwater is an inimitable resource that provides water to communities especially in arid and semi-arid regions. However, the spatial variability of the resource as well as the heterogeneity and complex nature of aquifer systems that store groundwater presents difficulties for groundwater development. Thus, understanding the spatial structure of aquifer characteristics could be used as a resourceful tool and as a first point of call towards groundwater development. The study investigated aquifer characteristics particularly on transmissivity and specific capacity to determine how aquifer characteristics could be used in making predictions for new sites that need to be identified for potential groundwater development. Prediction maps were developed for transmissivity and specific capacity using ordinary kriging J-Bessel and exponential semi variograms techniques. The study revealed that 28% of the study area had high potential for groundwater development with transmissivity ranges of 34.40 – 46.52 m2/d. Equally, viable areas of 16% and 20% were identified with transmissivities of 27.99 – 34.39 m2/d and 13.07 – 19.47 m2/d respectively. Based on specific capacity, 21% of the study area was identified to have groundwater development potential with corresponding specific capacity of 13.54 – 20.7 m2/d. Similarly, 24% and 34% of the study area were also identified to be good for the exploitation of groundwater with corresponding specific capacities of 8.74 – 13.55 m2/d and 5.52 – 8.74 m2/d respectively. In terms of spatial structure, transmissivity was found to be variable compared to specific capacity. The application of Geographic Information Systems (GIS) is thus considered to be an immeasurable tool that could be used in mapping aquifer characteristics that can serve as firsthand information for groundwater development.Keywords: Spatial, Groundwater, Transmissivity, Specific capacity, Kriging, Semivariogram       Â
Relationship between chlorophyll content in leaves of sorghum and pigeonpea determined by extraction method and by chlorophyll meter (SPAD-502)
The estimation of chlorophyll content in leaves by the chlorophyll meter (SPAD 502) is more convenient than by the extraction method for studies on photosynthesis or senescence where the total chlorophyll is estimated on the same leaf over time. This study was to test hypothesis that specific leaf weight (SLW) appears to be one of the factors determining SPAD index under different conditions. The influence of SLW on SPAD index and an improved simple method to determine chlorophyll content of sorghum and pigeonpea by a chlorophyll meter was studied. The results indicated that regression lines were significantly different between sorghum and pigeonpea, and at the vegetative and physiological maturity stages in each crop. Residuals of simple regressions calculated from all data of each crop were correlated with SLW. Multiple-regression with SPAD index as the dependent variable, and chlorophyll content and SLW as the independent variables gave the best estimation of chlorophyll content in leaves of sorghum and pigeonpea. These results suggest that SLW is an important factor affecting SPAD index and the influence of SLW on SPAD index can vary with crop species. Devices for estimating SLW could be incorporated into the chlorophyll meter to provide SPAD values adjusted for SLW. Further investigation is required on the influence of SLW on SPAD index for other crops
Adatoms and clusters of 3d transition metals on graphene: Electronic and magnetic configurations
We investigate the electronic and magnetic properties of single Fe, Co, and
Ni atoms and clusters on monolayer graphene (MLG) on SiC(0001) by means of
scanning tunneling microscopy (STM), x-ray absorption spectroscopy, x-ray
magnetic circular dichroism (XMCD), and ab initio calculations. STM reveals
different adsorption sites for Ni and Co adatoms. XMCD proves Fe and Co adatoms
to be paramagnetic and to exhibit an out-of-plane easy axis in agreement with
theory. In contrast, we experimentally find a nonmagnetic ground state for Ni
monomers while an increasing cluster size leads to sizeable magnetic moments.
These observations are well reproduced by our calculations and reveal the
importance of hybridization effects and intra-atomic charge transfer for the
properties of adatoms and clusters on MLG.Comment: 8 pages (supplementary included), 4 figures, (supplementary included
Energy conservation in citrus processing. Final project report
Alternative energy conserving systems for use in citrus processing plants were synthesized and evaluated in terms of energy savings and economic return. The energy intensive operations that are carried out in citrus processing plants include conveying and extraction, concentration, peel drying, refrigeration, and pasteurization. The alternative energy conserving systems are synthesized from components and subsystems that are arranged to make use of energy cascading and thermodynamic regeneration to reduce the overall energy usage. System requirements such as air pollution rules and plant processing load cycles, a characterization of major operations, description of alternative system concepts, and the evaluation of alternative systems in terms of economic parameters and energy usage are identified
Machine Learning Applications in Renewable Energy (MLARE) Research: A Publication Trend and Bibliometric Analysis Study (2012-2021)
This study examines the research climate on machine learning applications in renewable energy (MLARE). Therefore, the publication trends (PT) and bibliometric analysis (BA) on MLARE research published and indexed in the Elsevier Scopus database between 2012 and 2021 were examined. The PT was adopted to deduce the major stakeholders, top-cited publications, and funding organizations on MLARE, whereas BA elucidated critical insights into the research landscape, scientific developments, and technological growth. The PT revealed 1218 published documents comprising 46.9% articles, 39.7% conference papers, and 6.0% reviews on the topic. Subject area analysis revealed MLARE research spans the areas of science, technology, engineering, and mathematics among others, which indicates it is a broad, multidisciplinary, and impactful research topic. The most prolific researcher, affiliations, country, and funder are Ravinesh C. Deo, National Renewable Energy Laboratory, United States, and the National Natural Science Foundation of China, respectively. The most prominent journals on the top are Applied Energy and Energies, which indicates that journal reputation and open access are critical considerations for the author’s choice of publication outlet. The high productivity of the major stakeholders in MLARE is due to collaborations and research funding support. The keyword co-occurrence analysis identified four (4) clusters or thematic areas on MLARE, which broadly describe the systems, technologies, tools/technologies, and socio-technical dynamics of MLARE research. Overall, the study showed that ML is critical to the prediction, operation, and optimization of renewable energy technologies (RET) along with the design and development of RE-related materials
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Evolutionary expansion and divergence in a large family of primate-specific zinc finger transcription factor genes
Although most genes are conserved as one-to-one orthologs in different mammalian orders, certain gene families have evolved to comprise different numbers and types of protein-coding genes through independent series of gene duplications, divergence and gene loss in each evolutionary lineage. One such family encodes KRAB-zinc finger (KRAB-ZNF) genes, which are likely to function as transcriptional repressors. One KRAB-ZNF subfamily, the ZNF91 clade, has expanded specifically in primates to comprise more than 110 loci in the human genome, yielding large gene clusters in human chromosomes 19 and 7 and smaller clusters or isolated copies at other chromosomal locations. Although phylogenetic analysis indicates that many of these genes arose before the split between old world monkeys and new world monkeys, the ZNF91 subfamily has continued to expand and diversify throughout the evolution of apes and humans. The paralogous loci are distinguished by sequence divergence within their zinc finger arrays indicating a selection for proteins with different DNA binding specificities. RT-PCR and in situ hybridization data show that some of these ZNF genes can have tissue-specific expression patterns, however many KRAB-ZNFs that are near-ubiquitous could also be playing very specific roles in halting target pathways in all tissues except for a few, where the target is released by the absence of its repressor. The number of variant KRAB-ZNF proteins is increased not only because of the large number of loci, but also because many loci can produce multiple splice variants, which because of the modular structure of these genes may have separate and perhaps even conflicting regulatory roles. The lineage-specific duplication and rapid divergence of this family of transcription factor genes suggests a role in determining species-specific biological differences and the evolution of novel primate traits
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