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Effects of Over-Harvesting and Drought on a Predator-Prey System with Optimal Control

Open Journal of Ecology 2018年第8期8卷 459-482页

作者： Alanus Mapunda Eunice Mureithi Nyimvua Shaban thadei sagamiko Department of Mathematics University of Dar es Salaam Dar es Salaam Tanzania Department of Mathematics Physics and Informatics University of Dar es Salaam Dar es Salaam Tanzania

In this paper, a two species predator-prey model is developed where prey is affected by over-harvesting and drought and predator is affected by drought. The intention is to investigate the impact of over-harvesting and drought on predator-prey system, and suggest control strategies to alleviate the problem of loss of prey and predator species due to over-harvesting and drought. The control strategies suggested are creation of reserve areas with restriction of harvesting for controlling over-harvesting and construction of dams for mitigating drought effects. The results obtained from theoretical and numerical simulation of the predator-prey model with harvesting and drought without control strategies showed that, both harvesting and drought affect the predator-prey population negatively. However, the results obtained from numerical simulations of the model with control measures showed that, the use of control strategies one at a time encourages the increase of the prey and predator species to the optimal population size. Furthermore, the best result is obtained when control strategies, creation of reserve areas with restriction of harvesting and construction of dams are applied simultaneously.

关键词： Predator-Prey System Over-Harvesting Drought Optimal Control

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Regression Models of the Impact of Rockmass and Blast Design Variations on the Effectiveness of Iron Ore Surface Blasting

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Engineering（科研） 2011年第1期3卷 55-62页

作者： Antipas thadei Safari Massawe Karim Rajabu Baruti 不详

The desired economics of hard rock surface mining is mainly determined by the parameters of process design which minimize the overall cost per tonne of the rock mined in drilling, blasting, handling and primary crushing in given rockmass conditions. The most effective parameters of process design could be established based on the regression models of the cumulative influence of rockmass and mine design parameters on the overall cost per tonne of the rock drilled, blasted, handled and crushed. These models could be developed from the huge data accumulated worldwide on the costs per tonne of hard rock surface mining in drilling, blasting, handling and primary crushing vs the parameters of rockmass and mine design. This paper only dwelt on the development of regression models for oversize generation, blasthole productivity and blasting cost for iron ore surface mines, whose data is available. The SPSS standard statistical correlation – regression analysis software was used in the analysis. Interpretation of the models generated shows that the individual effects of the determinant rockmass and blast design parameters on oversize generation, blasthole productivity and blasting cost are all in compliance with the findings of other researchers and the theory of explosive rock fragmentation and could be used for the estimation of oversize generation, blasthole productivity and blasting cost in rockmass and blast design conditions similar to those of the iron ore surface mines examined in this study. However, the regression models obtained here could not be used alone for the optimization of blast design because most of the determinant parameters also have conflicting effect on the other processes of drilling, handling and primary crushing the blasted rock. Also, the quality and content of the regression models could be enhanced further by increasing the content of rockmass and blast design parameters and the volume of data considered in the regression analysis.

关键词： Blasting Effectiveness Oversize generation Blasthole Productivity Blasting Cost Rockmass Parameters Blast Design Parameters Regression Models

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Assessment of Environmental Cleaning Practices and the Impacts on Infection Prevention and Control in Selected Hospitals in Tanzania

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Journal of Environmental Protection 2022年第10期13卷 698-715页

作者： Honest Anicetus Samwel Manyele Michael Habtu Adolf Kiyunge Josephat Saria Robert Njee Linda thadei Khalid Massa Grace Elizabeth Saguti Zabulon Yoti Ministry of Health Community Development Gender Elderly and Children Dodoma Tanzania Department of Chemical and Mining Eng. University of Dar es Salaam Dar es Salaam Tanzania World Health Organization (WHO) Tanzania Dar es Salaam Tanzania Department of Environmental Studies The Open University of Tanzania Dar es Salaam Tanzani National Institute of Medical Research Dar es Salaam Tanzania National Council for Technical Education Dar es Salaam Tanzania

To achieve Sustainable Development Goal (SDG) in healthcare facilities (HCFs,) the provision of water, sanitation, healthcare waste management, hand hygiene and environmental cleanliness services is crucial. Good WASH services in HCFs settings have the potential to reduce healthcare acquired infections (HAIs), increase trust and uptake of healthcare services, increase efficiency and improve staff morale. To address this, a National Assessment was carried out to ascertain environmental cleanliness condition of the healthcare facilities at all levels. The assessment of healthcare waste management in the facilities was conducted in all the 26 regions of Tanzania Mainland including districts and lower healthcare facilities. A standardized checklist and tools were used to assess and monitor various aspects related to healthcare waste management using open source software for data collection (ODK). Data were analyzed using SPSS computer software. It was observed that most of permanent staff (88%) in the Healthcare facilities had knowledge on hand hygiene, but the gap was observed to the waste handlers (12%) who were not equipped with the hand hygiene knowledge. About 89% of the hand washing stations were available at mortuary units, followed by 75% at main entrance and the lowest was 3% at waste zone areas of the healthcare facilities. Hand washing materials like soap were mainly found at theaters (64%) followed by mortuary (60%) and last at waste zones. The assessment concludes that handling of healthcare wastes is not practiced to the expectations, and there is a need to strengthen the situation. The findings provide evidence for those engaged in improving HCF conditions to develop evidence-based policies and efficient programs, enhance service delivery systems, and make better use of available resources.

关键词： Environmental Cleaning Infection Prevention Sanitation Hand Hygiene and Water Supplies

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Assessment of Environmental Cleaning Practices and the Impacts on Infection Prevention and Control in Selected Hospitals in Tanzania

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Journal of Environmental Protection（环境保护） 2022年第10期

作者： honest anicetus samwel manyele michael habtu adolf kiyunge josephat saria robert njee linda thadei khalid massa grace elizabeth saguti zabulon yoti

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