5,745 research outputs found

    Why Northern Ghana Lags Behind in Ghana's Growth and Poverty Reduction Success

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    Ghana's post adjustment growth and poverty reduction performance has been hailed as impressive, albeit with spatial disparities in the distribution of welfare, especially between the north and south of the country. Researchers generally agree that economic growth does not always reduce poverty. Indeed, the effectiveness of growth in reducing poverty depends on the level of inequality in the population. Growth that increases inequality may not reduce poverty; growth that does not change inequality (distribution-neutral growth) and growth that reduces inequality (pro-poor growth) result in poverty reduction. Policy makers can promote pro-poor growth by empowering the poor to participate in growth directly. Policy makers can focus on interventions that improve productivity in smallholder agriculture, particularly export crops, increasing employment of semi-skilled or unskilled labour, promoting technology adoption, increasing access to production assets, as well as effective participation in input and product markets. Also, increasing public spending on social services and infrastructure made possible by redistribution of the benefits of growth benefits the poor, indirectly

    Characterization of Freshwater Natural Dissolved Organic Matter (DOM): Mechanistic Explanations for Protective Effects Against Metaltoxicity and Direct Effects on Organisms

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    Dissolved organic matter (DOM) exerts direct and indirect influences on aquatic organisms. In order to better understand how DOM causes these effects, potentiometric titration was carried out for a wide range of autochthonous and terrigenous freshwater DOM isolates. The isolates were previously characterized by absorbance and fluorescence spectroscopy. Proton binding constants (pKa) were grouped into three classes:acidic (pKa ≤ 5), intermediate (5 \u3c pKa ≤ 8.5) and basic (pKa \u3e 8.5). Generally, the proton site densities (LT) showed maximum peaks at the acidic and basic ends around pKa values of 3.5 and 10, respectively. More variably positioned peaks occurred in the intermediate pKa range. The acid–base titrations revealed the dominance of carboxylic and phenolic ligands with a trend for more autochthonous sources to have higher total LT. A summary parameter, referred to as the Proton Binding Index (PBI), was introduced to summarize chemical reactivity of DOMs based on the data of pKa and LT. Then, the already published spectroscopic data were explored and the specific absorbance coefficient at 340 nm (i.e. SAC340), an index of DOM aromaticity,was found to exhibit a strong correlation with PBI. Thus, the tendencies observed in the literature that darker organic matter is more protective against metal toxicity and more effective in altering physiological processes in aquatic organisms can now be rationalized on a basis of chemical reactivity to protons

    The Influence of Dissolved Organic Matter (DOM) on Sodium Regulation and Nitrogenous Waste Excretion in the Zebrafish (Danio rerio)

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    Dissolved organic matter (DOM) is both ubiquitous and diverse in composition in natural waters, but its effects on the branchial physiology of aquatic organisms have received little attention relative to other variables (e.g. pH, hardness, salinity, alkalinity). Here, we investigated the effects of four chemically distinct DOM isolates (three natural, one commercial, ranging from autochthonous to highly allochthonous, all at ∼6 mg C l−1) on the physiology of gill ionoregulation and nitrogenous waste excretion in zebrafish acclimated to either circumneutral (7.0–8.0) or acidic pH (5.0). Overall, lower pH tended to increase net branchial ammonia excretion, net K+ loss and [3H]PEG-4000 clearance rates (indicators of transcellular and paracellular permeability, respectively). However, unidirectional Na+ efflux, urea excretion and drinking rates were unaffected. DOM sources tended to stimulate unidirectional Na+ influx rate and exerted subtle effects on the concentration-dependent kinetics of Na+ uptake, increasing maximum transport capacity. All DOM sources reduced passive Na+ efflux rates regardless of pH, but exerted negligible effects on nitrogenous waste excretion, drinking rate, net K+ loss or [3H]PEG4000 clearance, so the mechanism of Na+ loss reduction remains unclear. Overall, these actions appear beneficial to ionoregulatory homeostasis in zebrafish, and some may be related to physicochemical properties of the DOM sources. They are very different from those seen in a recent parallel study on Daphnia magna using the same DOM isolates, indicating that DOM actions may be both species and DOM specific

    Application of 2D Electrical Resistivity Imaging Technique for Engineering Site Investigation

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    ان تحري الموقع الهندسي مهم لدراسة خصائص التربة تحت سطح الأرض لمواقع البناء المقترحة. يوفر استخدام طريقة المقاومة النوعية الكهربائية التصويرية ثنائية البعد معلومات مفيدة عن جيولوجيا وظروف ما تحت السطح على امتداد مسارات. في هذه الدراسة، تم اعتماد النمذجة الرقمية والدراسة الحقلية باستخدام تقنية المقاومة النوعية الكهربائية ثنائية البعد لأغراض تحري المواقع الهندسية. تم استخدام ترتيب فنر- شلمبرجر للاقطاب على امتداد ثلاثة مسارات متوازية في موقع للبناء في جامعة ديالى شمال شرق مدينة بغداد للكشف عن المرافق المدفونة (أنابيب) التي تركت في المنطقة. تم تصميم موديل افتراضي لانبوب مدفون لغرض المناقشة والتحقق من صحة النتائج الحقلية. لقد بينت مقاطع المقاومة النوعية الكهربائية ثنائية البعد للموديل امكانية الكشف عن التراكيب المدفونة حتى بوجود مستوى ضجيج مقدار 5% .لقد اظهر تفسير البيانات الحقلية أن تقنية المقاومة النوعية الكهربائية ثنائية البعد كانت فعالة في تحديد الانابيب المدفونة. ان حساسية ترتيب فنر- شلمبرجر للتغيرات الرأسية والأفقية في المقاومة النوعية  الكهربائية للتربة تحت السطح جعلت من الممكن تحديد موقع وشكل هذه التراكيب المدفونة. لقد اكدت الدراسة الحالية فائدة تقنية المقاومة النوعية الكهربائية التصويرية كأداة مكملة لتحريات المواقع الهندسية.Engineering site investigation is crucial to characterize the subsurface soil of proposed construction sites. Application of 2D Electrical Resistivity Imaging ERI technique pro- vides useful information about the subsurface geology and the condition along profiles. In this paper, numerical and field studies using 2D ERI technique were adopted for engineer- ing site investigation purposes. The Wenner-Schlumberger array was implemented along three parallel profiles at the construction site of Diyala University, northeast of Baghdad city, to detect buried utilities (pipes) left over in the area. A synthetic resistivity model of a buried pipe was designed to discuss and validate the field results. The 2D ERI sections of the model resolve clearly the buried structure, even with 5% noise level. Interpretation of the field data showed that 2D ERI technique was effective in delineating the buried pipes. The vertical and horizontal sensitivity of the Wenner-Schlumberger array for sub- surface resistivity variations made it possible to determine the position and geometry of the buried structures. The current work demonstrates the usefulness of the ERI technique as a complementary tool for engineering site investigation

    Assessment of Ore Grade Estimation Methods for Structurally Controlled Vein Deposits - A Review

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    Resource estimation techniques have upgraded over the past couple of years, thereby improving resource estimates. The classical method of estimation is less used in ore grade estimation than geostatistics (kriging) which proved to provide more accurate estimates by its ability to account for the geology of the deposit and assess error. Geostatistics has therefore been said to be superior over the classical methods of estimation. However, due to the complexity of using geostatistics in resource estimation, its time-consuming nature, the susceptibility to errors due to human interference, the difficulty in applying it to deposits with few data points and the difficulty in using it to estimate complicated deposits paved the way for the application of Artificial Intelligence (AI) techniques to be applied in ore grade estimation. AI techniques have been employed in diverse ore deposit types for the past two decades and have proven to provide comparable or better results than those estimated with kriging. This research aimed to review and compare the most commonly used kriging methods and AI techniques in ore grade estimation of complex structurally controlled vein deposits. The review showed that AI techniques outperformed kriging methods in ore grade estimation of vein deposits.   Keywords: Artificial Intelligence, Neural Networks, Geostatistics, Kriging, Mineral Resource, Grad

    Valuation of Agricultural Weather Information Networks

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    Weather Information, Networks, Irrigation, Crop Production/Industries, Farm Management, Production Economics, Resource /Energy Economics and Policy, Risk and Uncertainty,

    Characterization of Freshwater Natural Dissolved Organic Matter (DOM): Mechanistic Explanations for Protective Effects Against Metaltoxicity and Direct Effects on Organisms

    Get PDF
    Dissolved organic matter (DOM) exerts direct and indirect influences on aquatic organisms. In order to better understand how DOM causes these effects, potentiometric titration was carried out for a wide range of autochthonous and terrigenous freshwater DOM isolates. The isolates were previously characterized by absorbance and fluorescence spectroscopy. Proton binding constants (pKa) were grouped into three classes:acidic (pKa ≤ 5), intermediate (5 \u3c pKa ≤ 8.5) and basic (pKa \u3e 8.5). Generally, the proton site densities (LT) showed maximum peaks at the acidic and basic ends around pKa values of 3.5 and 10, respectively. More variably positioned peaks occurred in the intermediate pKa range. The acid–base titrations revealed the dominance of carboxylic and phenolic ligands with a trend for more autochthonous sources to have higher total LT. A summary parameter, referred to as the Proton Binding Index (PBI), was introduced to summarize chemical reactivity of DOMs based on the data of pKa and LT. Then, the already published spectroscopic data were explored and the specific absorbance coefficient at 340 nm (i.e. SAC340), an index of DOM aromaticity,was found to exhibit a strong correlation with PBI. Thus, the tendencies observed in the literature that darker organic matter is more protective against metal toxicity and more effective in altering physiological processes in aquatic organisms can now be rationalized on a basis of chemical reactivity to protons

    The Influence of Dissolved Organic Matter (DOM) on Sodium Regulation and Nitrogenous Waste Excretion in the Zebrafish (Danio rerio)

    Get PDF
    Dissolved organic matter (DOM) is both ubiquitous and diverse in composition in natural waters, but its effects on the branchial physiology of aquatic organisms have received little attention relative to other variables (e.g. pH, hardness, salinity, alkalinity). Here, we investigated the effects of four chemically distinct DOM isolates (three natural, one commercial, ranging from autochthonous to highly allochthonous, all at ∼6 mg C l−1) on the physiology of gill ionoregulation and nitrogenous waste excretion in zebrafish acclimated to either circumneutral (7.0–8.0) or acidic pH (5.0). Overall, lower pH tended to increase net branchial ammonia excretion, net K+ loss and [3H]PEG-4000 clearance rates (indicators of transcellular and paracellular permeability, respectively). However, unidirectional Na+ efflux, urea excretion and drinking rates were unaffected. DOM sources tended to stimulate unidirectional Na+ influx rate and exerted subtle effects on the concentration-dependent kinetics of Na+ uptake, increasing maximum transport capacity. All DOM sources reduced passive Na+ efflux rates regardless of pH, but exerted negligible effects on nitrogenous waste excretion, drinking rate, net K+ loss or [3H]PEG4000 clearance, so the mechanism of Na+ loss reduction remains unclear. Overall, these actions appear beneficial to ionoregulatory homeostasis in zebrafish, and some may be related to physicochemical properties of the DOM sources. They are very different from those seen in a recent parallel study on Daphnia magna using the same DOM isolates, indicating that DOM actions may be both species and DOM specific

    Designing carbon nanotube-based oil absorbing membranes from gamma irradiated and electrospun polystyrene nanocomposites

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    Carbon-based materials are outstanding candidates for oil spill clean-ups due to their superhydrophobicity, high surface area, chemical inertness, low density, recyclability, and selectivity. The current work deals with the fabrication of membrane oil absorbents based on carbon nanotube (CNT) reinforced polystyrene (PS) nanocomposites by electrospinning technique. The spun membranes are also irradiated with the gamma radiation to induce enough crosslinks and thus good polymer-filler interactions. The structural, morphological, and surface properties in addition to the oil/water separation efficiency were investigated by varying the concentration of CNT and the dose of γ-irradiation. Fabricated nanofiber membranes show superior hydrophobicity and selective oil absorption at 0.5 wt.% of CNT concentration. The best mechanical properties are also obtained at this particular concentration and at 15 KGy optimum γ-irradiation dosage. The gamma irradiated PS/0.5 wt.% CNT membrane also exhibits good antibacterial effects against the bacteria, Escherichia coli, in the form of bacterial inhibition rings around the membranes. The present study thus shows the environmental applicability of the fabricated PS/CNT membranes in treating oil-contaminated water

    Characterizing Epistemic Uncertainty for Launch Vehicle Designs

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    NASA Probabilistic Risk Assessment (PRA) has the task of estimating the aleatory (randomness) and epistemic (lack of knowledge) uncertainty of launch vehicle loss of mission and crew risk and communicating the results. Launch vehicles are complex engineered systems designed with sophisticated subsystems that are built to work together to accomplish mission success. Some of these systems or subsystems are in the form of heritage equipment, while some have never been previously launched. For these cases, characterizing the epistemic uncertainty is of foremost importance, and it is anticipated that the epistemic uncertainty of a modified launch vehicle design versus a design of well understood heritage equipment would be greater. For reasons that will be discussed, standard uncertainty propagation methods using Monte Carlo simulation produce counter intuitive results and significantly underestimate epistemic uncertainty for launch vehicle models. Furthermore, standard PRA methods such as Uncertainty-Importance analyses used to identify components that are significant contributors to uncertainty are rendered obsolete since sensitivity to uncertainty changes are not reflected in propagation of uncertainty using Monte Carlo methods.This paper provides a basis of the uncertainty underestimation for complex systems and especially, due to nuances of launch vehicle logic, for launch vehicles. It then suggests several alternative methods for estimating uncertainty and provides examples of estimation results. Lastly, the paper shows how to implement an Uncertainty-Importance analysis using one alternative approach, describes the results, and suggests ways to reduce epistemic uncertainty by focusing on additional data or testing of selected components
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