5,091 research outputs found

    On load balancing via switch migration in software-defined networking

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    Switch-controller assignment is an essential task in multi-controller software-defined networking. Static assignments are not practical because network dynamics are complex and difficult to predetermine. Since network load varies both in space and time, the mapping of switches to controllers should be adaptive to sudden changes in the network. To that end, switch migration plays an important role in maintaining dynamic switch-controller mapping. Migrating switches from overloaded to underloaded controllers brings flexibility and adaptability to the network but, at the same time, deciding which switches should be migrated to which controllers, while maintaining a balanced load in the network, is a challenging task. This work presents a heuristic approach with solution shaking to solve the switch migration problem. Shift and swap moves are incorporated within a search scheme. Every move is evaluated by how much benefititwillgivetoboththeimmigrationandoutmigrationcontrollers.Theexperimentalresultsshowthat theproposedapproachisabletooutweighthestate-of-artapproaches,andimprovetheloadbalancingresults up to≈ 14% in some scenarios when compared to the most recent approach. In addition, the results show that the proposed work is more robust to controller failure than the state-of-art methods.Portuguese Science and Technology Foundation (FCT) - UID/MULTI/00631/2019;info:eu-repo/semantics/publishedVersio

    Illumination correction and analysis of two-dimensional microscopy images of Loa loa microfilariae

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    This thesis addresses the problem of detecting a common parasitic micro laria that causes loaisis, a major disease problem in Central and Western Africa. The dose of medicine to be administered to the patient is proportional to the estimated number of micro lariae in the patient's body. Therefore, proper estimation of the number of micro lariae is the key for conducting the right procedure. The clinical examination is necessary to estimate the micro lariae density in a blood sample drawn from the patient. Thereafter, visual inspection of the sample is performed. The main challenge in this work is, however, the development of an automatic detection system of micro lariae in 2-D images. Such problem is new in the image processing literature, and the development of such system is very important for performing better diagnosis and treatment of this disease and other similar diseases. A comprehensive review of, both generic and thin, object detectors in 2-D images is presented. A very robust method for microscopy image illumination correction is proposed, and a new powerful descriptor, the Hessian-Polar Context (HPC), for micro lariae is also introduced. These are then combined in a micro lariae detection system, where a simple, yet e cient, hypotheses generator is also presented. Additionally, several methods and applications for di erent image modalities are proposed. These involve a method and an application for the analysis of rice panicle in 2-D images. Additionally, an e cient method for artifact suppression in X-ray image is also proposed. The proposed methods are compared to a set of state-of-the-art methods. Experimental results show that the developed methods are great contributions to the microscopy and X-ray imaging elds

    Rotational and hyperfine analysis of the near infrared 3Φ4-X3Φ4 transitions of CoCl and Col

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    A rotational and hyperfine analysis of the 3φ 4- 3φ 4 transition of CoCl and CoI in the near infrared region was reported. Six and eight vibronic transition band soft CoCl and CoI, respectively, were recorded and analyzed. Accurate molecular parameters for both the upper and the ground 3φ 4 states were determined by least squares fitting of line positions of observed bands simultaneously for each molecule, which yielded accurate molecular parameters for both the upper and lower 3φ 4 states.published_or_final_versio

    Placement of Controllers in Software Defined Networking under Multiple Controller Mapping

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    This work focuses on the placement of controllers in software-defined networking architectures. A mathematical model is developed to place controllers under multi- controller switch-controller mapping, where a switch can be assigned to multiple controllers. Resiliency, scalability, and inter-plane latency are all modeled in the proposed model. A scalability factor is introduced to increase the load to capacity gap at controllers, preventing controllers to work near their capacity limit. The proposed model is shown to be effective and resilient under different failure scenarios while, at the same time, taking latency and scalability into consideration. Keywords: Controller Placement, Software-defined Networking, Reliability, Scalabilit

    Health promotion, disease prevention and periodic health checks: perceptions and practice among family physicians in eastern Mediterranean region

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    Introduction: The aim of this study was to identify the current practices and perceptions of family physicians regarding health promotion, disease prevention including periodic screening and health checks in Eastern Mediterranean Region. Methods: A multi-country cross-sectional study was conducted in six countries of EMR, from September 2014 to March 2015. Family Physicians who were currently practicing in different countries of EMR were invited to participate in the study through email. A pre-tested structured questionnaire was used for data collection. Data was entered and analyzed on SPSS 19 and logistic regression analysis was performed. Results: A total of 100 physicians data was included in the final analysis. The majority were female physicians (76%): 63% were 25 to 35 years of age. Approximately 53% of Family physicians always recommend periodic screening and health checks to their patients. The common screening question asked to patients in medical history was related to their blood pressure (86%). Almost all (99%) of the Family physicians believe they should conduct periodic health checks. Those who had postgraduate training in Family Medicine (OR: 0.5; 95% CI: 0.39-1.67) and attended CME sessions regularly (OR: 0.11; 95% CI: 0.01-0.93), are more likely to recommend periodic screening and health checks to their patients. Conclusion: Periodic screening and health check is an important strategy to prevent disease and maintain health. It is an underutilized practice and a great need exists for its implementation in family practice

    Optimization of Mixed Numerology Profiles for 5G Wireless Communication Scenarios

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    The management of 5G resources is a demanding task, requiring proper planning of operating numerology indexes and spectrum allocation according to current traffic needs. In addition, any reconfigurations to adapt to the current traffic pattern should be minimized to reduce signaling overhead. In this article, the pre-planning of numerology profiles is proposed to address this problem, and a mathematical optimization model for their planning is developed. The idea is to explore requirements and impairments usually present in a given wireless communication scenario to build numerology profiles and then adopt one of the profiles according to the current users/traffic pattern. The model allows the optimization of mixed numerologies in future 5G systems under any wireless communication scenario, with specific service requirements and impairments, and under any traffic scenario. Results show that, depending on the granularity of the profiles, the proposed optimization model is able to provide satisfaction levels of 60–100%, whereas a non-optimized approach provides 40–65%, while minimizing the total number of numerology indexes in operation.Competitiveness and Internationalization Operational Programme (COMPETE 2020), the Regional Operational Program of the Algarve (2020), and Fundação para a Ciência e Tecnologia; i-Five: Extensão do acesso de espectro dinâmico para rádio 5G, POCI-01-0145-FEDER-030500. This work is also supported by Fundação para a ciência e Tecnologia within CEOT (Center for Electronic, Optoelectronic and Telecommunications) and the UID/MULTI/00631/2020 projectinfo:eu-repo/semantics/publishedVersio

    Arab Women's Breast Cancer Screening Practices: A Literature Review

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    Breast cancer incidence and mortality rates are increasing in the Arab world and the involved women are often diagnosed at advanced stages of breast cancer. This literature review explores factors influencing Arab women’s breast cancer screening behavior. Searched databases were: Medline, PubMed, Cochrane Database of Systematic Reviews, CINAHL Plus, Google Scholar, Index Medicus for WHO Eastern Mediterranean, and Asian Pacific Journal of Cancer Prevention. Breast cancer screening participation rates are low. Screening programs are opportunistic and relatively new to the region. Knowledge amongst women and health care providers, professional recommendation, socio-demographic factors, cultural traditions, beliefs, religious, social support, accessibility and perceived effectiveness of screening influence screening behavior
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