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- Ståhl, Björn
(författare)
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Monitoring Infrastructure Affordances
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Computing has made its way into most of our lives as a key processor of vast quantities of information. This has happened directly in terms of gadgets and devices that assists us in everyday life, but also indirectly, through the critical infrastructures that enables these devices to function. A key issue with critical infrastructures such as transportation, communication, power-grids and finance, is increasingly circular interdependencies. Because of this issue, a disruption in either one can cascade and have a global effect on the others. To manage these complexities, we are depending on a number of monitoring systems that allow operators and other stakeholders to, within their respective expert domains, discover disruptions as early as possible and then take appropriate actions. These monitoring systems are not without challenges of their own. In addition to having evolved organically alongside their respective infrastructures, there is a considerable legacy to account for, with both hardware and software components spanning decades of computing history. This puts heavy restrictions on the kinds of interventions that can be performed safely, implying that these systems are ill fit for handling the software and software security landscapes of today, where updates and adjustments need to be applied on a daily basis in order to stand a fighting chance. The work presented herein address some of the major challenges in securing these monitoring systems against current and future threats posed by antagonistic actors, dormant software defects and changes imposed by technological advances and academic discoveries. This is approached on several fronts in parallel: by embedding resilience in order to allow for controlled experimentation and evaluation of new protection mechanisms in incrementally sensitive settings; by developing laboratory facilities for resilient smart power-grids; and by developing tools and training scenarios for operators of adaptive and reconfigurable monitoring systems.
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- Hansson, Helena, et al.
(författare)
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A framework to assess the resilience of farming systems
- 2019
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Ingår i: Agricultural Systems. - : Elsevier BV. - 0308-521X .- 1873-2267. ; 176
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Tidskriftsartikel (refereegranskat)abstract
- Agricultural systems in Europe face accumulating economic, ecological and societal challenges, raising concerns about their resilience to shocks and stresses. These resilience issues need to be addressed with a focus on the regional context in which farming systems operate because farms, farmers' organizations, service suppliers and supply chain actors are embedded in local environments and functions of agriculture. We define resilience of a farming system as its ability to ensure the provision of the system functions in the face of increasingly complex and accumulating economic, social, environmental and institutional shocks and stresses, through capacities of robustness, adaptability and transformability. We (i) develop a framework to assess the resilience of farming systems, and (ii) present a methodology to operationalize the framework with a view to Europe's diverse farming systems. The framework is designed to assess resilience to specific challenges (specified resilience) as well as a farming system's capacity to deal with the unknown, uncertainty and surprise (general resilience). The framework provides a heuristic to analyze system properties, challenges (shocks, long-term stresses), indicators to measure the performance of system functions, resilience capacities and resilience-enhancing attributes. Capacities and attributes refer to adaptive cycle processes of agricultural practices, farm demographics, governance and risk management. The novelty of the framework pertains to the focal scale of analysis, i.e. the farming system level, the consideration of accumulating challenges and various agricultural processes, and the consideration that farming systems provide multiple functions that can change over time. Furthermore, the distinction between three resilience capacities (robustness, adaptability, transformability) ensures that the framework goes beyond narrow definitions that limit resilience to robustness. The methodology deploys a mixed-methods approach: quantitative methods, such as statistics, econometrics and modelling, are used to identify underlying patterns, causal explanations and likely contributing factors; while qualitative methods, such as interviews, participatory approaches and stakeholder workshops, access experiential and contextual knowledge and provide more nuanced insights. More specifically, analysis along the framework explores multiple nested levels of farming systems (e.g. farm, farm household, supply chain, farming system) over a time horizon of 1-2 generations, thereby enabling reflection on potential temporal and scalar trade-offs across resilience attributes. The richness of the framework is illustrated for the arable farming system in Veenkolonien, the Netherlands. The analysis reveals a relatively low capacity of this farming system to transform and farmers feeling distressed about transformation, while other members of their households have experienced many examples of transformation.
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- Larsson, Matilda, et al.
(författare)
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Ultrasound speckle tracking for radial, longitudinal and circumferential strain estimation of the carotid artery : An in vitro validation via sonomicrometry using clinical and high-frequency ultrasound
- 2014
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Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 56, s. 399-408
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasound speckle tracking for carotid strain assessment has in the past decade gained interest in studies of arterial stiffness and cardiovascular diseases. The aim of this study was to validate and directly contrast carotid strain assessment by speckle tracking applied on clinical and high-frequency ultrasound images in vitro. Four polyvinyl alcohol phantoms mimicking the carotid artery were constructed with different mechanical properties and connected to a pump generating carotid flow profiles. Gray-scale ultrasound long-and short-axis images of the phantoms were obtained using a standard clinical ultrasound system, Vivid 7 (GE Healthcare, Horten, Norway) and a high-frequency ultrasound system, Vevo 2100 (FUJIFILM, VisualSonics, Toronto, Canada) with linear-array transducers (12L / MS250). Radial, longitudinal and circumferential strains were estimated using an in-house speckle tracking algorithm and compared with reference strain acquired by sonomicrometry. Overall, the estimated strain corresponded well with the reference strain. The correlation between estimated peak strain in clinical ultrasound images and reference strain was 0.91 (p < 0.001) for radial strain, 0.73 (p < 0.001) for longitudinal strain and 0.90 (p < 0.001) for circumferential strain and for high-frequency ultrasound images 0.95 (p < 0.001) for radial strain, 0.93 (p < 0.001) for longitudinal strain and 0.90 (p < 0.001) for circumferential strain. A significant larger bias and root mean square error was found for circumferential strain estimation on clinical ultrasound images compared to high frequency ultrasound images, but no significant difference in bias and root mean square error was found for radial and longitudinal strain when comparing estimation on clinical and high-frequency ultrasound images. The agreement between sonomicrometry and speckle tracking demonstrates that carotid strain assessment by ultrasound speckle tracking is feasible.
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