| 1. |
- Hägglund, Patricia, 1989-
(författare)
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Swallowing dysfunction among older people in short-term care : prevalence, effect of intervention, and risk of mortality
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Objectives: Swallowing dysfunction (dysphagia) is a common, but often neglected condition among geriatric patients that can cause severe complications such as malnutrition, aspiration pneumonia and death. The aims of this thesis were to (i) describe the study design and method of the multidisciplinary and multicenter project SOFIA (Swallowing function, Oral health, and Food Intake in old Age), (ii) study the prevalence of and the relationship between swallowing dysfunction and risk of undernutrition among older individuals in short-term care, (iii) study the effect of oral neuromuscular training on swallowing dysfunction among older individuals, and (iv) to investigate the association between poor oral health, swallowing dysfunction and mortality.Methods: This thesis includes four original papers that are all part of the SOFIA project. Paper Iis the study protocol. In total, 391 individuals aged 65 or older, from 36 short-term care units were included in the project. At baseline the participants’ status regarding swallowing function (assessed with the Timed Water Swallow Test, TWST), oral health (using the Revised Oral Assessment Guide, ROAG) and nutrition (assessed with the Minimal Eating Observation and Nutrition Form-version II, MEONF-II) were assessed and collected by calibrated professionals. Clinical data were also collected. Paper IIwas a cross-sectional study where the baseline assessments of the participants’ swallowing function and nutritional status were obtained and the relationship analyzed. Paper IIIwas a cluster randomized, controlled trial (cRCT) that included 116 participants identified with swallowing dysfunction in paper II. These participants were randomly assigned to either usual care (control group) or oral neuromuscular training (intervention group). All participants were assessed at baseline, after five weeks’ training and six months after end-of-treatment, regarding swallowing function and swallowing-related quality of life (QOL). Paper IVwas a prospective cohort study where all participants were followed-up 1-year after inclusion to investigate risk factors for mortality by analysis of the associations between swallowing dysfunction, poor oral health, and 1-year survival. Results: Paper II:The median age of the 391 participants was 84 years (Interquartile range [IQR] 11) and 209 (53%) were females. In total, 248 of the 385 (64%) participants showed swallowing dysfunction, and risk of undernutrition was observed in 91 of 390 (23%) participants. The adjusted logistics regression model revealed that participants with swallowing dysfunction had significantly higher odds of undernutrition than those with normal swallowing (Odds ratio [OR]: 1.74, 95% Confidence interval [CI] 1.04 to 2.92, P=0.034).Paper III: At end-of-treatment, a linear mixed model showed significant between-group differences of changes in swallowing efficacy between baseline and after completed treatment period (Ratio 1.60, 95% CI 1.15 to 2.29, P=0.007); indicating a 60% higher swallowing efficacy in the intervention group compared with the control group. Paper IV: A mixed effects Cox model showed that swallowing dysfunction and poor oral health were both independently associated with 1-year mortality (adjusted Hazard Ratio [aHR]: 1.67, 95% CI 1.02 to 2.75,P=0.041 and aHR: 1.98, 95% CI 1.07 to 3.65, P=0.029, respectively). In addition, swallowing dysfunction and poor oral health in combination predicted the highest mortality rate (35%, P<0.001).Conclusion: Swallowing dysfunction is highly prevalent and a risk factor for undernutrition among older people in short-term care. Oral neuromuscular training improves swallowing dysfunction and is thus a promising method of swallowing rehabilitation for older people with impaired swallowing. Swallowing dysfunction and poor oral health are independent risk factors for 1-year morality among older people in short-term care. Therefore, systematic screening and intervention to improve swallowing dysfunction and poor oral health are important to achieve healthy aging and to prevent undernutrition and early death.
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| 2. |
- Byrne, James, et al.
(författare)
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A review of cloud computing simulation platforms and related environments
- 2017
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Ingår i: Proceedings of the 7th International Conference on Cloud Computing and Services Science. - : SciTePress. - 9789897582431 ; , s. 679-691
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Konferensbidrag (refereegranskat)abstract
- Recent years have seen an increasing trend towards the development of Discrete Event Simulation (DES) platforms to support cloud computing related decision making and research. The complexity of cloud environments is increasing with scale and heterogeneity posing a challenge for the efficient management of cloud applications and data centre resources. The increasing ubiquity of social media, mobile and cloud computing combined with the Internet of Things and emerging paradigms such as Edge and Fog Computing is exacerbating this complexity. Given the scale, complexity and commercial sensitivity of hyperscale computing environments, the opportunity for experimentation is limited and requires substantial investment of resources both in terms of time and effort. DES provides a low risk technique for providing decision support for complex hyperscale computing scenarios. In recent years, there has been a significant increase in the development and extension of tools to support DES for cloud computing resulting in a wide range of tools which vary in terms of their utility and features. Through a review and analysis of available literature, this paper provides an overview and multi-level feature analysis of 33 DES tools for cloud computing environments. This review updates and extends existing reviews to include not only autonomous simulation platforms, but also on plugins and extensions for specific cloud computing use cases. This review identifies the emergence of CloudSim as a de facto base platform for simulation research and shows a lack of tool support for distributed execution (parallel execution on distributed memory systems).
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| 3. |
- Gonzalo P., Rodrigo, 1980-
(författare)
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HPC scheduling in a brave new world
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many breakthroughs in scientific and industrial research are supported by simulations and calculations performed on high performance computing (HPC) systems. These systems typically consist of uniform, largely parallel compute resources and high bandwidth concurrent file systems interconnected by low latency synchronous networks. HPC systems are managed by batch schedulers that order the execution of application jobs to maximize utilization while steering turnaround time. In the past, demands for greater capacity were met by building more powerful systems with more compute nodes, greater transistor densities, and higher processor operating frequencies. Unfortunately, the scope for further increases in processor frequency is restricted by the limitations of semiconductor technology. Instead, parallelism within processors and in numbers of compute nodes is increasing, while the capacity of single processing units remains unchanged. In addition, HPC systems’ memory and I/O hierarchies are becoming deeper and more complex to keep up with the systems’ processing power. HPC applications are also changing: the need to analyze large data sets and simulation results is increasing the importance of data processing and data-intensive applications. Moreover, composition of applications through workflows within HPC centers is becoming increasingly important. This thesis addresses the HPC scheduling challenges created by such new systems and applications. It begins with a detailed analysis of the evolution of the workloads of three reference HPC systems at the National Energy Research Supercomputing Center (NERSC), with a focus on job heterogeneity and scheduler performance. This is followed by an analysis and improvement of a fairshare prioritization mechanism for HPC schedulers. The thesis then surveys the current state of the art and expected near-future developments in HPC hardware and applications, and identifies unaddressed scheduling challenges that they will introduce. These challenges include application diversity and issues with workflow scheduling or the scheduling of I/O resources to support applications. Next, a cloud-inspired HPC scheduling model is presented that can accommodate application diversity, takes advantage of malleable applications, and enables short wait times for applications. Finally, to support ongoing scheduling research, an open source scheduling simulation framework is proposed that allows new scheduling algorithms to be implemented and evaluated in a production scheduler using workloads modeled on those of a real system. The thesis concludes with the presentation of a workflow scheduling algorithm to minimize workflows’ turnaround time without over-allocating resources.
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| 4. |
- Gonzalo P., Rodrigo, 1980-, et al.
(författare)
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ScSF : a scheduling simulation framework
- 2018
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Ingår i: Job Scheduling Strategies for Parallel Processing. - Cham : Springer. - 9783319773971 - 9783319773988 ; , s. 152-173
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Konferensbidrag (refereegranskat)abstract
- High-throughput and data-intensive applications are increasingly present, often composed as workflows, in the workloads of current HPC systems. At the same time, trends for future HPC systems point towards more heterogeneous systems with deeper I/O and memory hierarchies. However, current HPC schedulers are designed to support classical large tightly coupled parallel jobs over homogeneous systems. Therefore, There is an urgent need to investigate new scheduling algorithms that can manage the future workloads on HPC systems. However, there is a lack of appropriate models and frameworks to enable development, testing, and validation of new scheduling ideas.In this paper, we present an open-source scheduler simulation framework (ScSF) that covers all the steps of scheduling research through simulation. ScSF provides capabilities for workload modeling, workload generation, system simulation, comparative workload analysis, and experiment orchestration. The simulator is designed to be run over a distributed computing infrastructure enabling to test at scale. We describe in detail a use case of ScSF to develop new techniques to manage scientific workflows in a batch scheduler. In the use case, such technique was implemented in the framework scheduler. For evaluation purposes, 1728 experiments, equivalent to 33 years of simulated time, were run in a deployment of ScSF over a distributed infrastructure of 17 compute nodes during two months. Finally, the experimental results were analyzed in the framework to judge that the technique minimizes workflows’ turnaround time without over-allocating resources. Finally, we discuss lessons learned from our experiences that will help future researchers.
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| 5. |
- Grunér, Sofia, et al.
(författare)
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The Compensatory Effect of Text-to-Speech Technology on Reading Comprehension and Reading Rate in Swedish Schoolchildren With Reading Disability : The Moderating Effect of Inattention and Hyperactivity Symptoms Differs by Grade Groups
- 2018
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Ingår i: Journal of Special Education Technology. - : SAGE Publications. - 0162-6434 .- 2381-3121. ; 33:2, s. 98-110
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was (i) to investigate if the compensatory effect of text-to-speech (TTS) technology on reading comprehension and reading rate in schoolchildren with reading disability is influenced by problems with inattention and hyperactivity and (ii) to examine whether a potentially moderating effect of such symptoms differ between grade groups. Participants (N = 49) were randomized into one of the two experimental conditions: Group A listened to a text with TTS, and Group B read the text themselves. The conditions were then switched. Inattention and hyperactivity symptoms were assessed with the Strengths and Difficulties Questionnaire (SDQ). Statistical analyses were performed both on the whole group and within-grade groups (Grades 3–5 and 6–9). Using TTS technology had a positive effect on reading rate for both grade groups, and this effect was not influenced by attention-deficit/hyperactivity disorder (ADHD) symptoms. As for reading comprehension, the two groups differed both with respect to the amount of improvement seen in the TTS condition and with respect to the moderating effect of ADHD symptoms. Reading with TTS improved reading comprehension significantly in the younger group, whereas no effect on reading comprehension was found in the older group. A higher score on the SDQ ADHD Scale was associated with less improvement in reading comprehension in the younger group and with greater improvement in reading comprehension in the older group. The results indicate that symptoms of inattention and hyperactivity, as well as the child’s grade level, are factors that should be taken into account when planning and introducing TTS technology.
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| 6. |
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| 7. |
- Krzywda, Jakub, et al.
(författare)
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A Sensor-Actuator Model for Data Center Optimization
- 2015
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Ingår i: 2015 International Conference on Cloud and Autonomic Computing (ICCAC). - : IEEE Computer Society. - 9781467395663 ; , s. 192-195
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Konferensbidrag (refereegranskat)abstract
- Cloud data centers commonly use virtualization technologies to provision compute capacity with a level of indirection between virtual machines and physical resources. In this paper we explore the use of that level of indirection as a means for autonomic data center configuration optimization and propose a sensor-actuator model to capture optimization-relevant relationships between data center events, monitored metrics (sensors data), and management actions (actuators). The model characterizes a wide spectrum of actions to help identify the suitability of different actions in specific situations, and outlines what (and how often) data needs to be monitored to capture, classify, and respond to events that affect the performance of data center operations.
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| 8. |
- Krzywda, Jakub, 1989-, et al.
(författare)
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ALPACA : Application Performance Aware Server Power Capping
- 2018
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Ingår i: ICAC 2018. - : IEEE Computer Society. - 9781538651391 ; , s. 41-50
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Konferensbidrag (refereegranskat)abstract
- Server power capping limits the power consumption of a server to not exceed a specific power budget. This allows data center operators to reduce the peak power consumption at the cost of performance degradation of hosted applications. Previous work on server power capping rarely considers Quality-of-Service (QoS) requirements of consolidated services when enforcing the power budget. In this paper, we introduce ALPACA, a framework to reduce QoS violations and overall application performance degradation for consolidated services. ALPACA reduces unnecessary high power consumption when there is no performance gain, and divides the power among the running services in a way that reduces the overall QoS degradation when the power is scarce. We evaluate ALPACA using four applications: MediaWiki, SysBench, Sock Shop, and CloudSuite’s Web Search benchmark. Our experiments show that ALPACA reduces the operational costs of QoS penalties and electricity by up to 40% compared to a non optimized system.
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| 9. |
- Krzywda, Jakub, 1989-
(författare)
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Analysing, modelling and controlling power-performance tradeoffs in data center infrastructures
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this thesis is to analyse the power-performance tradeoffs in datacenter servers, create models that capture these tradeoffs, and propose controllers to optimise the use of data center infrastructures taking the tradeoffs into consideration. The main research problem that we investigate in this thesis is how to increase the power efficiency of data center servers taking into account the power-performance tradeoffs.The main cause for this research is the massive power consumption of data centers that is a concern both from the financial and environmental footprint perspectives. Irrespectively of the approaches taken to enhance data center power efficiency, substantial reductions in the power consumption of data center servers easily lead to performance degradation of hosted applications, which causes customers dissatisfaction. Therefore, it is crucial for the data center operators to understand and control the power-performance tradeoffs.The research methods used in this thesis include experiments on real testbeds, applying statistical methods to create power-performance models, development of various optimisation techniques to improve the energy-efficiency of servers, and simulations to evaluate proposed solutions at scale.As a result of the research presented in this thesis, we propose taxonomies for selected aspects of data center configurations, events, management actions, and monitored metrics. We discuss the relationships between these elements and to support the analysis present results from a set of testbed experiments.We show limitations in the applicability of various data center management actions, including Dynamic Voltage Frequency Scaling (DVFS), Running Average Power Limit (RAPL), CPU Pinning, horizontal and vertical scaling. Finally, we propose a power budgeting controller that minimizes the performance degradation while enforcing the power limits.The outcomes of this thesis can be used by the data center operators to improve the energy-efficiency of servers and reduce the overall power consumption with minimized performance degradation. Moreover, the software artifacts including virtual machine images, scripts, and simulator are available online.Future work includes further investigation of the problem of graceful performance degradation under power limits, incorporating multi-layer applications spread among several servers and load balancing controller.
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| 10. |
- Krzywda, Jakub, 1989-
(författare)
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May the power be with you : managing power-performance tradeoffs in cloud data centers
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall goal of the work presented in this thesis was to find ways of managing power-performance tradeoffs in cloud data centers. To this end, the relationships between the power consumption of data center servers and the performance of applications hosted in data centers are analyzed, models that capture these relationships are developed, and controllers to optimize the use of data center infrastructures are proposed.The studies were motivated by the massive power consumption of modern data centers, which is a matter of significant financial and environmental concern. Various strategies for improving the power efficiency of data centers have been proposed, including server consolidation, server throttling, and power budgeting. However, no matter what strategy is used to enhance data center power efficiency, substantial reductions in the power consumption of data center servers can easily degrade the performance of hosted applications, causing customer dissatisfaction. It is therefore crucial for data center operators to understand and control power-performance tradeoffs.The research methods used in this work include experiments on real testbeds, the application of statistical methods to create power-performance models, development of various optimization techniques to improve the power efficiency of servers, and simulations to evaluate the proposed solutions at scale.This thesis makes multiple contributions. First, it introduces taxonomies for various aspects of data center configuration, events, management actions, and monitored metrics. We discuss the relationships between these elements and support our analysis with results from a set of testbed experiments. We demonstrate limitations on the usefulness of various data center management actions for controlling power consumption, including Dynamic Voltage Frequency Scaling (DVFS) and Running Average Power Limit (RAPL). We also demonstrate similar limitations on common measures for controlling application performance, including variation of operating system scheduling parameters, CPU pinning, and horizontal and vertical scaling. Finally, we propose a set of power budgeting controllers that act at the application, server, and cluster levels to minimize performance degradation while enforcing power limits.The results and analysis presented in this thesis can be used by data center operators to improve the power-efficiency of servers and reduce overall operational costs while minimizing performance degradation. All of the software generated during this work, including controller source code, virtual machine images, scripts, and simulators, has been open-sourced.
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