133 research outputs found

    Quality-of-service provisioning for dynamic heterogeneous wireless sensor networks

    Get PDF
    A Wireless Sensor Network (WSN) consists of a large collection of spatially dis- tributed autonomous devices with sensors to monitor physical or environmental conditions, such as air-pollution, temperature and traffic flow. By cooperatively processing and communicating information to central locations, appropriate ac- tions can be performed in response. WSNs perform a large variety of applications, such as the monitoring of elderly persons or conditions in a greenhouse. To correctly and efficiently perform a task, the behaviour of the WSN should be such that sufficient Quality-of-Service (QoS) is provided. QoS is defined by constraints and objectives on network quality metrics, such as a maximum end- to-end packet loss or minimum network lifetime. After defining the application we want the WSN to perform, many steps are involved in designing the WSN such that sufficient QoS is provided. First, a (heterogeneous) set of sensor nodes and protocols need to be selected. Furthermore, a suitable deployment has to be found and the network should be configured for its first use. This configuration involves setting all controllable parameters that influence its behaviour, such as selecting the neighbouring node(s) to communicate to and setting the transmission power of its radio, to ensure that the WSN provides the required QoS. Configuring the network is a complex task as the number of parameters and their possible values are large and trade-offs between multiple quality metrics exist. High transmission power may result in a low packet loss to a neighbouring node, but also in a high power consumption and low lifetime. Heterogeneity in the network causes the impact of parameters to be different between nodes, requiring parameters of nodes to be set individually. Moreover, a static configuration is typically not sufficient to make the most efficient trade-off between the quality metrics at all times in a dynamic environment. Run-time mechanisms are needed to maintain the required level of QoS under changing circumstances, such as changing external interference, mobility of nodes or fluctuating traffic load. This thesis deals with run-time reconfiguration of dynamic heterogeneous wire- less sensor networks to maintain a required QoS, given a deployed network with selected communication protocols and their controllable parameters. The main contribution of this thesis is an efficient QoS provisioning strategy. It consists of three parts: a re-active reconfiguration method, a generic distributed service to estimate network metrics and a pro-active reconfiguration method. In the re-active method, nodes collaboratively respond to discrepancies be- tween the current and required QoS. Nodes use feedback control which, at a given speed, adapts parameters of the node to continuously reduce any error between the locally estimated network QoS and QoS requirements. A dynamic predictive model is used and updated at run-time, to predict how different parameter adap- tations influence the QoS. Setting the speed of adaptation allows us to influence the trade-off between responsiveness and overhead of the approach, and to tune it to the characteristics of the application scenario. Simulations and experiments with an actual deployment show the successful integration in practical scenar- ios. Compared to existing configuration strategies, we are able to extend network lifetime significantly, while maintaining required packet delivery ratios. To solve the non-trivial problem of efficiently estimating network quality met- rics, we introduce a generic distributed service to distributively compute various network metrics. This service takes into account the possible presence of links with asymmetric quality that may vary over time, by repeated forwarding of informa- tion over multiple hops combined with explicit information validity management. The generic service is instantiated from the definition of a recursive local update function that converges to a fixed point representing the desired metric. We show the convergence and stability of various instantiations. Parameters can be set in accordance with the characteristics of the deployment and influence the trade-off between accuracy and overhead. Simulations and experiments show a significant increase in estimation accuracy, and efficiency of a protocol using the estimates, compared to today’s current approaches. This service is integrated in various protocol stacks providing different kinds of network metric estimates. The pro-active reconfiguration method reconfigures in response to predefined run-time detectable events that may cause the network QoS to change signifi- cantly. While the re-active method is generally applicable and independent of the application scenario, the, complementary, pro-active method exploits any a-priori knowledge of the application scenario to adapt more efficiently. A simple example is that as soon as a person with a body sensor node starts walking we know that several aspects, including the network topology, will change. To avoid degradation of network QoS, we pro-actively adapt parameters, in this case, for instance, the frequency of updating the set of neighbouring nodes, as soon as we observe that a person starts to walk. At design time, different modes of operation are selected to be distinguished at run-time. Analysis techniques, such as simulations, are used to determine a suitable configuration for each of these modes. At run time, the approach ensures that nodes can detect the mode in which they should operate. We describe the integration of the pro-active method for two practical monitoring applications. Simulations and experiments show the feasibility of an implementa- tion on resource constrained nodes. The pro-active reconfiguration allows for an efficient QoS provisioning in combination with the re-active approach

    Anime in Tourism: An Analysis of Norwegian Anime Enthusiasts’ Motivation for Conducting Anime-Induced Travels to Japan

    Get PDF
    Anime is a part of Japan’s biggest growing markets outside of Japan (JNTO, n.d. a; AJA, 2018). What attracts overseas consumers to watch anime ranges from everything to having coherent and interesting storylines, Japanese culture elements (Thelle, 2009; Yegulalp, 2018) to unique styles and drawings (JNTO, 2011; Yegulalp, 2018). Anime can also be connected to tourism and is more specifically referred to as anime pilgrimage or anime tourism, where fans conduct travels to locations featured in anime films or television shows (Okamoto, 2015; Beeton, 2016). What motivates fans to conduct anime travels to Japan can be due to several different reasons. In this thesis, I have chosen to focus on Norwegian anime enthusiasts’ motivations for conducting anime-induced travels to Japan. I have discussed their motivations regarding theories revolving around film ‘imaginaries’, anime tourist behaviour and motivation, as well as what characterizes an experience in regards to the Experience Realms model (Pine II & Gilmore, 1999). Motivators that were individually answered by the Norwegian enthusiasts will in addition also be discussed and analysed. Such motivators revolved around ‘travelling out of interest’, ‘travelling to meet individuals with the same interests’, and to ‘experience anime theme parks’. The Norwegian anime enthusiasts’ answers have also been analysed and discussed in terms of which anime enthusiast category they fit the description of

    A priority-based budget scheduler with conservative dataflow model.

    Get PDF
    Currently, the guaranteed throughput of a stream processing application, mapped on a multi-processor system, can be computed with a conservative dataflow model, if only time division multiplex (TDM) schedulers are applied. A TDM scheduler is a budget scheduler. Budget schedulers can be characterized by two parameters: budget and replenishment interval. This paper introduces a priority-based budget scheduler (PBS), which is a budget scheduler that additionally associates a priority with every task. PBS improves the guaranteed minimum throughput of a stream processing application compared to TDM, given the same amount of resources. We construct a conservative dataflow model for a task scheduled by PBS. This dataflow model generalizes previous work, because it is valid for a sequence of execution times instead of one execution time per task which results in an improved accuracy of the model. Given this dataflow model, we can compute the guaranteed minimum throughput of the task graph that implements the stream processing application. Experiments confirm that a significantly higher guaranteed minimum throughput of the task graph can be obtained with PBS instead of TDM schedulers and that a conservative bound on the guaranteed throughput of the task graph can be computed with a dataflow model. Furthermore, our bound on the guaranteed throughput of the task graph is accurate, if the buffer capacities in the task graph do not affect the guaranteed throughput

    Development of high amylose wheat through TILLING

    Get PDF
    BACKGROUND: Wheat (Triticum spp.) is an important source of food worldwide and the focus of considerable efforts to identify new combinations of genetic diversity for crop improvement. In particular, wheat starch composition is a major target for changes that could benefit human health. Starches with increased levels of amylose are of interest because of the correlation between higher amylose content and elevated levels of resistant starch, which has been shown to have beneficial effects on health for combating obesity and diabetes. TILLING (Targeting Induced Local Lesions in Genomes) is a means to identify novel genetic variation without the need for direct selection of phenotypes. RESULTS: Using TILLING to identify novel genetic variation in each of the A and B genomes in tetraploid durum wheat and the A, B and D genomes in hexaploid bread wheat, we have identified mutations in the form of single nucleotide polymorphisms (SNPs) in starch branching enzyme IIa genes (SBEIIa). Combining these new alleles of SBEIIa through breeding resulted in the development of high amylose durum and bread wheat varieties containing 47-55% amylose and having elevated resistant starch levels compared to wild-type wheat. High amylose lines also had reduced expression of SBEIIa RNA, changes in starch granule morphology and altered starch granule protein profiles as evaluated by mass spectrometry. CONCLUSIONS: We report the use of TILLING to develop new traits in crops with complex genomes without the use of transgenic modifications. Combined mutations in SBEIIa in durum and bread wheat varieties resulted in lines with significantly increased amylose and resistant starch contents

    Pulmonary and cardiac variables associated with persistent dyspnea after pulmonary embolism

    Get PDF
    Introduction: Persistent dyspnea is common in follow-up after pulmonary embolism (PE), but the underlying mechanisms are poorly understood. Material and methods: This cross-sectional study included subjects aged 18?75 years with confirmed PE by computed tomography pulmonary angiography (CTPA) 6?72 months earlier. A total of 180 participants underwent clinical examination, incremental shuttle walk test, laboratory tests, transthoracic echocardiography, pulmonary function tests and ventilation/perfusion scintigraphy. In further analysis, we divided participants into two groups; ?dyspnea? or ?no dyspnea?, based on interview and questionnaires at inclusion. The association of cardiac and pulmonary variables with persistent dyspnea was assessed using multiple logistic regression analysis. Results: In total, 44% (95% CI: 39%?51%) of the participants reported persistent dyspnea after PE. Age (adjusted odds ratio (aOR) 0.93 per year, 95% CI: 0.90?0.97, P = 0.001), body mass index (BMI) (aOR 1.14 per kg/m2, 95% CI: 1.04?1.25, P = 0.004), recurrent venous thromboembolism (VTE) (aOR 3.69, 95% CI: 1.45?9.38, P = 0.006) and diffusion capacity of the lung for carbon monoxide (DLCO) (aOR 0.95 per increase of 1%, 95% CI: 0.92?0.98, P = 0.001) were independently associated with persistent dyspnea. Conclusions: Persistent dyspnea was prevalent after PE. Age, BMI and recurrent VTE were independently associated with dyspnea. Apart from reduced DLCO, no other cardiac or pulmonary variables were associated with persistent dyspnea.Thrombosis and Hemostasi

    A survey of individual preference for colorectal cancer screening technique

    Get PDF
    BACKGROUND: Due to the low participation in colorectal cancer screening, public preference for colorectal cancer screening modality was determined. METHODS: A cross-sectional survey was performed of healthy ambulatory adults in a pediatrics primary care office and neighboring church. Overall preference was ranked for each of four colorectal cancer screening modalities: Faecal Occult Blood, Fiberoptic Sigmoidoscopy, Barium Enema and Colonoscopy. Four additional domains of preference also were ranked: suspected discomfort, embarrassment, inconvenience and danger of each exam. RESULTS: 80 surveys were analyzed, 57 of which were received from participants who had experienced none of the screening tests. Fecal Occult Blood Testing is significantly preferred over each other screening modality in overall preference and every domain of preference, among all subjects and those who had experienced none of the tests. CONCLUSIONS: Efforts to increase public participation in colorectal cancer screening may be more effective if undertaken in the context of public perceptions of screening choices

    Patient satisfaction with healthcare provided by family doctors: primary dimensions and an attempt at typology

    Get PDF
    <p>Abstract</p> <p>Background</p> <p>Patient satisfaction is a complex and difficult concept to measure, thus precluding the use of exclusively quantitative methods for its description. The purpose of this survey was firstly to identify particular healthcare dimensions that determine a patient's satisfaction or dissatisfaction; and secondly to attempt to typologise the patients' responses based on their evaluation of healthcare.</p> <p>Methods</p> <p>Using a qualitative research design, thirty-six in-depth interviews with patients of family physicians were conducted: four patients from each of 9 family practices in different regions of Poland were interviewed. The main outcome measure was factors associated with patient satisfaction/dissatisfaction.</p> <p>Results</p> <p>In their evaluations of their contacts with family doctors, the patients cited mostly issues concerning interpersonal relationships with the doctor. Nearly 40% of the statements referred to this aspect of healthcare, with nearly equal proportions of positive and negative comments. The second most frequent category of responses concerned contextual factors (21%) that related to conditions of medical service, with two-thirds of the evaluations being negative. Statements concerning the doctor's competencies (12.9%) and personal qualities (10.5%) were less common.</p> <p>Conclusion</p> <p>To improve the quality of healthcare, family doctors should take special care to ensure the quality of their interactions with patients.</p

    Satisfaction is not all – patients' perceptions of outcome of general practice consultations, a qualitative study

    Get PDF
    BACKGROUND: Evaluation of outcome in general practice can be seen from different viewpoints. In this study we focus on the concepts patients use to describe the outcome of a consultation with a GP. METHOD: Patients were interviewed within a week after a consultation with a GP. The interviews were made with 20 patients in 5 focus groups and 8 individually. They were analysed with a phenomenographic research approach. RESULTS: From the patient's perspective, the outcome of a consultation is about cure or symptom relief, understanding, confirmation, reassurance, change in self-perception and satisfaction. CONCLUSION: General practice consultations are often more important for patients than generally supposed. Understanding is the most basic concept
    corecore