8,143 research outputs found

    Outbursts of Young Stellar Objects

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    We argue that the outbursts of the FU Orionis stars occur on timescales which are much longer than expected from the standard disc instability model with \alpha_{c} \gtrsim 10^{-3}. The outburst, recurrence, and rise times are consistent with the idea that the accretion disc in these objects is truncated at a radius R_{i} \sim 40 \rsun. In agreement with a number of previous authors we suggest that the inner regions of the accretion discs in FU Ori objects are evacuated by the action of a magnetic propeller anchored on the central star. We develop an analytic solution for the steady state structure of an accretion disc in the presence of a central magnetic torque, and present numerical calculations to follow its time evolution. These calculations confirm that a recurrence time that is consistent with observations can be obtained by selecting appropriate values for viscosity and magnetic field strength.Comment: 13 pages, 7 figures, accepted by MNRA

    National Hospital Management Portal (NHMP): a framework for e-health implementation

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    Health information represents the main basis for health decisionmaking process and there have been some efforts to increase access to health information in developing countries. However, most of these efforts are based on the internet which has minimal penetration especially in the rural and sub-urban part of developing countries. In this work, a platform for medical record acquisition via the ubiquitous 2.5G/3G wireless communications technologies is presented. The National Hospital Management Portal (NHMP)platform has a central database at each specific country’s national hospita

    Estimating An Optimal Backpropagation Algorithm for Training An ANN with the EGFR Exon 19 Nucleotide Sequence: An Electronic Diagnostic Basis for Non–Small Cell Lung Cancer(NSCLC)

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    One of the most common forms of medical malpractices globally is an error in diagnosis. An improper diagnosis occurs when a doctor fails to identify a disease or report a disease when the patient is actually healthy. A disease that is commonly misdiagnosed is lung cancer. This cancer type is a major health problem internationally because it is responsible for 15% of all cancer diagnosis and 29% of all cancer deaths. The two major sub-types of lung cancer are; small cell lung cancer (about 13%) and non-small cell lung cancer (%SCLC- about 87%). The chance of surviving lung cancer depends on its correct diagnosis and/or the stage at the time it is diagnosed. However, recent studies have identified somatic mutations in the epidermal growth factor receptor (EGFR) gene in a subset of non-small cell lung cancer (%SCLC) tumors. These mutations occur in the tyrosine kinase domain of the gene. The most predominant of the mutations in all %SCLC patients examined is deletion mutation in exon 19 and it accounts for approximately 90% of the EGFR-activating mutations. This makes EGFR genomic sequence a good candidate for implementing an electronic diagnostic system for %SCLC. In this study aimed at estimating an optimum backpropagation training algorithm for a genomic based A%% system for %SCLC diagnosis, the nucleotide sequences of EGFR’s exon 19 of a noncancerous cell were used to train an artificial neural network (A%%). Several A%% back propagation training algorithms were tested in MATLAB R2008a to obtain an optimal algorithm for training the network. Of the nine different algorithms tested, we achieved the best performance (i.e. the least mean square error) with the minimum epoch (training iterations) and training time using the Levenberg-Marquardt algorithm

    Automatic Electrical Appliances Control Panel Based on Infrared and Wi-Fi: A Framework for Electrical Energy Conservation

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    -Today, proprietary home automation targets very specific applications which operate mostly on a cable based infrastructure. In contrast to that, our implementation builds on a wireless platform for the automatic control of house hold electrical appliances. The nodes gather sensor readings in a home and transmit them to a central automation server. There, the readings are matched against a list of script statements. When there is a match, a specific action is performed. An important property of the system is that the control of all home appliances is done by means of the ubiquitous Infrared and Wi-Fi wireless technologies. This way, the co-operation between manufacturers is not a necessity in order to connect devices to the home automation network

    The steady-state structure of accretion discs in central magnetic fields

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    We develop a new analytic solution for the steady-state structure of a thin accretion disc under the influence of a magnetic field that is anchored to the central star. The solution takes a form similar to that of Shakura and Sunyaev and tends to their solution as the magnetic moment of the star tends to zero. As well as the Kramer's law case, we obtain a solution for a general opacity. The effects of varying the mass transfer rate, spin period and magnetic field of the star as well as the opacity model applied to the disc are explored for a range of objects. The solution depends on the position of the magnetic truncation radius. We propose a new approach for the identification of the truncation radius and present an analytic expression for its position.Comment: 11 pages, 7 figures, accepted by MNRA

    Development of a Solar Photovoltaic Vulcanizing Machine towards Extreme Poverty Eradication in Africa

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    The number of African families living in extreme poverty has continued to increase even though the proportion of the citizens in such situation in this region declined in recent years. This is traceable to unemployment, underemployment, and income inequalities that have generated social unrest as joblessness persist. However, entrepreneurship through small and medium-scale enterprises (SMEs) has the capacity to drive economic growth and national development through job creation, income empowerment, and poverty eradication. Roadside vulcanizing business in towns and cities of Africa is a viable job that can be run by any age group and it requires no formal training or long apprenticeship to develop expertise. Unfortunately, the cost of running the fossil fuel-powered vulcanizing machine will leave the technician with little or no profit due to the recent fuel subsidy removal by some countries like Nigeria. In addition, overdependence on fossil fuel as a primary source of energy promotes the negative effects of carbon dioxide and other global warming emissions on environment, climate, and public health. In this paper, considering the abundant solar energy potential across all the Sub-Saharan countries, we designed and constructed a solar photovoltaic vulcanizing machine as a practical means of eradicating extreme poverty in line with the 2030 Sustainable Development Goals (SDGs) agenda. The implementation of this project will create employment opportunities for millions of Africans, reduce social violence and crime, provide affordable and clean energy, and save our planet

    Plastic Mannequin-Based Robotic Telepresence for Remote Clinical Ward Rounding

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    Mobile robotic telepresence is a potential solution to addressing the problem of access to quality healthcare delivery in rural areas. Despite the availability of this system in its different forms, the capital and operating costs are unffordable for people living in rural areas, particularly in emerging economies. In this paper, the authors reduced the cost of mobile robotic telepresence solution for remote ward rounding using plastic mannequin and solar photovoltaic technology. An IP camera was fixed in each of the eye sockets of the plastic mannequin. These cameras are connected to a mini-computer embedded in the plastic mannequin. A Wi-Fi module establishes an Internet connection between remote physicians and rural healthcare facilities. In addition, most of these communities are not even connected to the power grid. Therefore, the system is powered by a solar photovoltaic energy source to provide a cheap and reliable power system. Another unique feature of this solution is that it gives the patient a better impression of the physical presence of a physician. This development will increase the adoption of robotic telepresense for remote clinical ward rounding in developing countrie

    Performance Enhancement of Quality of Service of IP Mobility for Real-Time Traffic

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    Future Internet traffic will be huge both for real time and non-real time traffic in an IP mobility environment due to proliferation of mobile nodes. MIPv4 is one of IETF defined IP mobility protocols but with QoS issues like end-to-end delay due to triangular routing, jitter and throughput. OPNET Modeler 14.5 was used in this research to simulate MIPv4 based WiMax network combining MPLS and Diffserv to improve upon the service quality of the network. The end-to-end delay for 20 mobile nodes (MN) was reduced considerably to less than 0.09 second for VoIP traffic and 0.7 second for video conferencing. Jitter was virtually eliminated and good improvement on service throughput. With this improvement in MIPv4 network performance, it can be integrated with MIPv6 network for better future Internet service delivery
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