1,220 research outputs found

    The effect of environmental variability on livestock and land-use management: The Borana plateau, southern Ethiopia 

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    The Borana people are the predominant ethnic group on the Borana Plateau in southern Ethiopia. Though traditionally transhumant pastoralists, they have recently increased their reliance on crops. Rainfall in the region averages between 353 mm to 873 mm; variability in rainfall is quite high, with coefficients of variation ranging from.21 to.68. The past decade has witnessed a dramatic increase in land allocated to crops, and land in pastures that are either becoming privatised, or accessible to only a small sub-group of people. In this paper, we derive an empirical model of stocking rates and land allocation, which is then used to estimate the effects of exogenous parameters on stocking densities, land allocated to crops, and land allocated to private pastures. Results indicate the following: a) regions with high coefficients of variation in rainfall have lower livestock densities and less land allocated to crops, b) communities with greater numbers of households and higher population densities have larger indices of non-cooperation, higher stock densities, and more land allocated to crops, c) heterogeneity within a community, measured by the distribution of wealth levels, is positively related to an index of non-cooperation, and to higher stock densities, d) higher relative prices of livestock and shorter distances to market are associated with greater stock densities as well as greater land allocated to crops, e) the greater is mobility into an area, the higher are stock densities, and the lower is the cooperation level, whereas outward mobility by community members has no effect on either stock densities or the level of cooperation reached, f) the proportion of members engaged in wage work outside has a significant negative effect on the ability of the community to cooperate. Outside wage work also increases land allocated to crops, but has a significant negative effect on land allocated to private pastures, and g) the greater is the index of non-cooperation, the higher are stock densities and the greater is land allocated to crops.

    Making GDPR Usable: A Model to Support Usability Evaluations of Privacy

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    We introduce a new model for evaluating privacy that builds on the criteria proposed by the EuroPriSe certification scheme by adding usability criteria. Our model is visually represented through a cube, called Usable Privacy Cube (or UP Cube), where each of its three axes of variability captures, respectively: rights of the data subjects, privacy principles, and usable privacy criteria. We slightly reorganize the criteria of EuroPriSe to fit with the UP Cube model, i.e., we show how EuroPriSe can be viewed as a combination of only rights and principles, forming the two axes at the basis of our UP Cube. In this way we also want to bring out two perspectives on privacy: that of the data subjects and, respectively, that of the controllers/processors. We define usable privacy criteria based on usability goals that we have extracted from the whole text of the General Data Protection Regulation. The criteria are designed to produce measurements of the level of usability with which the goals are reached. Precisely, we measure effectiveness, efficiency, and satisfaction, considering both the objective and the perceived usability outcomes, producing measures of accuracy and completeness, of resource utilization (e.g., time, effort, financial), and measures resulting from satisfaction scales. In the long run, the UP Cube is meant to be the model behind a new certification methodology capable of evaluating the usability of privacy, to the benefit of common users. For industries, considering also the usability of privacy would allow for greater business differentiation, beyond GDPR compliance.Comment: 41 pages, 2 figures, 1 table, and appendixe

    Simulating planting date and cultivar effects on dryland maize production using CERESmaize model

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    Open Access JournalMaize farmers and extension agents in dry sudan savanna need information on how planting date and the choice of variety affect grain yield. This study was conducted to test the ability of model to predict maize yields under varying planting dates. Data on two open-pollinated maize cultivars (TSB-SR and TZE-COMP4) sown on different dates (June 29th, July 13th, July 21st and July 28th) in 2006 and 2007 at Azir (11° 01.820´ N, 12°37.714´ E; 441 m) and Damboa (11° 10.379´; 12° 47.145´E; 396 m) in the Sudan Savanna of Nigeria were used in running the model. Experimental data from Azir in 2006 was used to calibrate the model, while the data for 2007 at Azir 2006 and 2007 at Damboa were used for model validation. The model predicted days to anthesis at Damboa as reasonably well in both 2006 and 2007 (d-index >0.8), while at Azir, the prediction of days to anthesis was very poor in 2007. The match between predicted and observed grain yield were very good in 2007 at both locations. The root mean square error (RMSE) values for grain yield in 2007 were 431.5 and 226.5 kg ha-1 at Azir, and 799.5 and 611.5 kg ha-1 at Damboa for TZB SR and TZE COMP4, respectively, while the d-index values were all greater than 0.94. Generally, the model predicted decrease in grain yield with delay in planting date except for TZB-SR at Azir in 2006 where planting on July 13th gave higher yield than planting on June 29th. The grain yield values from the simulations suggested late June to early July as the optimum planting window for both varieties at both Azir and Damboa

    CERES-maize model for determining the optimum planting dates of early maturing maize varieties in northern Nigeria

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    Open Access JournalField trials were carried out in the Sudan Savannah of Nigeria to assess the usefulness of CERES–maize crop model as a decision support tool for optimizing maize production through manipulation of plant dates. The calibration experiments comprised of 20 maize varieties planted during the dry and rainy seasons of 2014 and 2015 at Bayero University Kano and Audu Bako College of Agriculture Dambatta. The trials for model evaluation were conducted in 16 different farmer fields across the Sudan (Bunkure and Garun—Mallam) and Northern Guinea (Tudun-Wada and Lere) Savannas using two of the calibrated varieties under four different sowing dates. The model accurately predicted grain yield, harvest index, and biomass of both varieties with low RMSE-values (below 5% of mean), high d-index (above 0.8), and high r-square (above 0.9) for the calibration trials. The time series data (tops weight, stem and leaf dry weights) were also predicted with high accuracy (% RMSEn above 70%, d-index above 0.88). Similar results were also observed for the evaluation trials, where all variables were simulated with high accuracies. Estimation efficiencies (EF)-values above 0.8 were observed for all the evaluation parameters. Seasonal and sensitivity analyses on Typic Plinthiustalfs and Plinthic Kanhaplustults in the Sudan and Northern Guinea Savannas were conducted. Results showed that planting extra early maize varieties in late July and early maize in mid-June leads to production of highest grain yields in the Sudan Savanna. In the Northern Guinea Savanna planting extra-early maize in mid-July and early maize in late July produced the highest grain yields. Delaying planting in both Agro-ecologies until mid-August leads to lower yields. Delaying planting to mid-August led to grain yield reduction of 39.2% for extra early maize and 74.4% for early maize in the Sudan Savanna. In the Northern Guinea Savanna however, delaying planting to mid-August resulted in yield reduction of 66.9 and 94.3% for extra-early and early maize, respectively

    Diagnostic accuracy of PAT-POPS and ManChEWS for admissions of children from the emergency department

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    Background The Pennine Acute Trust (PAT) Paediatric Observation Priority Score (PAT-POPS) is a specific emergency department (ED) physiological and observational aggregate scoring system, with scores of 0–18. A higher score indicates greater likelihood of admission. The Manchester Children’s Early Warning System (ManChEWS) assesses six physiological observations to create a trigger score, classified as Green, Amber or Red. Methods Prospectively collected data were used to calculate PAT-POPS and ManChEWS on 2068 patients aged under 16 years (mean 5.6 years, SD 4.6) presenting over 1 month to a UK District General Hospital Paediatric ED. Receiver operating characteristics (ROC) comparison, using STATA V.13, was used to investigate the ability of ManChEWS and PAT-POPS to predict admission to hospital within 72 h of presentation to the ED. Results Comparison of the area under the ROC curve indicates that the ManChEWS ROC is 0.67 (95% CI 0.64 to 0.70) and the PAT-POPS ROC is 0.72 (95% CI 0.68 to 0.75). The difference is statistically significant. At a PAT-POPS cut-off of ≥2, 80% of patients had their admission risk correctly classified ( positive likelihood ratio 3.40, 95% CI 2.90 to 3.98) whereas for ManChEWS with a cut off of ≥Amber only 71% of patients were correctly classified ( positive likelihood ratio 2.18, 95% CI 1.94 to 2.45). Conclusions PAT-POPS is a more accurate predictor of admission risk than ManChEWS. Replacing ManChEWS with PAT-POPS would appear to be clinically appropriate in a paediatric ED. This needs validation in a multicentre study

    Mid-term and cost-benefit study of smallholder farmers in Striga-Infested maize and cowpea growing areas of Northern Nigeria

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    The Bill and Melinda Gates Foundation (BMGF) provided a 4-year financial support to the International Institute for Tropical Agriculture (IITA) and other partners in 2011 to adapt and intensively promote proven integrated Striga management strategies in cowpea and maize farming systems in northern Nigeria and western Kenya, with the active participation of farmers, community-based organizations, extension workers, policy makers, and researchers. The objective of the project is to improve the livelihoods of over 25 million smallholder farmers in the immediate impact zones of the project in northern Nigeria (15 million) and western Kenya (10 million) in the long term by developing and implementing a robust “ Striga threat reduction strategy” that identifies and strategically promotes scientifically proven technologies that work on smallholder farmers’ fields and which have direct effects on stopping Striga emergence, reducing the Striga seed bank in the fields, improving soil fertility, and increasing crop yields. The management technologies being promoted in Northern Nigeria range from cultural practices such as crop rotation of maize with soybean which stimulates Striga to germinate but which later dies in the absence of the maize host to latch onto; and using Striga-resistant maize and cowpea varieties. The ISMA project is expected to end in 2015, thus, it is pertinent to carry out a mid-term evaluation of the project with respect to adoption and benefit-cost analysis of the Striga management technologies among farming households in the project areas and make a comparison with non-intervention areas. In Nigeria, the Integrated Striga Management in Africa (ISMA) project was implemented in Kano and Bauchi states, both located in the savanna agroecology of northern Nigeria. The mid-term evaluation will provide the basis to present ISMA’s achievement to policy makers, NARES, private sector partners, the BMGF, and other development partners. The result will also guide the scaling-up and scaling out of the project to other parts of the savanna ecological zones of northern Nigeria. It is within this context that the study was planned. The objectives of the study were to..

    Kinetics of coherent order-disorder transition in Al3ZrAl_3 Zr

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    Within a phase field approach which takes the strain-induced elasticity into account, the kinetics of the coherent order-disorder transition is investigated for the specific case of Al3ZrAl_3 Zr alloy. It is shown that a microstructure with cubic L12L1_2 precipitates appears as a transient state during the decomposition of a homogeneous disordered solid solution into a microstructure with tetragonal DO23DO_{23} precipitates embedded into a disordered matrix. At low enough temperature, favored by a weak internal stress, only L12L1_2 precipitates grow in the transient microstructure preceding nucleation of the DO23DO_{23} precipitates that occurs exclusively at the interface of the solid solution with the L12L1_2 precipitates. Analysis of microstructures at nanoscopic scale shows a characteristic rod shape for the DO23DO_{23} precipitates due to the combination of their tetragonal symmetry and their large internal stress.Comment: 2 postscript figures and 1 JPG pag
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