| 1. |
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| 2. |
- Boström, Pontus, 1982, et al.
(författare)
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Cytosolic lipid droplets increase in size by microtubule-dependent complex formation
- 2005
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Ingår i: Arterioscler Thromb Vasc Biol. - 1524-4636. ; 25:9, s. 1945-51
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Adipocyte differentiation-related protein (ADRP)-containing lipid droplets have an essential role in the development of insulin resistance and atherosclerosis. Such droplets form in a cell-free system with a diameter of 0.1 to 0.4 microm, while the droplets present in cells vary in size, from small to very large, suggesting that the droplets can increase in size after being assembled. We have addressed this possibility. METHODS AND RESULTS: Experiments in NIH 3T3 cells demonstrated that the lipid droplets could increase in size independently of triglyceride biosynthesis. NIH 3T3 cells were either microinjected with ADRP-GFP (green fluorescent protein) or stained with Nile Red and followed by confocal microscopy and time-lapse recordings. The results showed that lipid droplets formed complexes with each other, with a volume equal to the sum of the merging particles. The formation of complexes could be inhibited by the nocodazole-induced depolymerization of the microtubules; thus, the process is dependent on microtubules. The presence of dynein on ADRP-containing droplets supports a role for this motor protein. CONCLUSIONS: Lipid droplets can grow after they have been assembled. This increase in size is independent of triglyceride biosynthesis and involves formation of complexes, which requires intact microtubules.
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| 3. |
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| 4. |
- Ericsson, AnnMarie, et al.
(författare)
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Active Database Rulebase
- 2009
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Ingår i: Encyclopedia of Database Systems. - Boston, MA : Springer Science+Business Media B.V.. - 9780387496160 - 9780387355443 - 9780387399409 ; , s. 37-37
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Ericsson, AnnMarie, et al.
(författare)
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Composite Event
- 2009
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Ingår i: Encyclopedia of Database Systems. - Boston, MA : Springer Science+Business Media B.V.. - 9780387496160 - 9780387355443 - 9780387399409 ; , s. 418-419
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 6. |
- Ericsson, AnnMarie, et al.
(författare)
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Detecting Design Errors in Composite Events for Event Triggered Real-Time Systems Using Timed Automata
- 2006
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Ingår i: SCW 2006: IEEE Services Computing Workshops. - : IEEE. - 0769526810 - 9780769526812 ; , s. 39-47
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Konferensbidrag (refereegranskat)abstract
- Many applications need to detect and respond to occurring events and combine these event occurrences into new events with a higher level of abstraction. Specifying how events can be combined is often supported by design tools specific to the current event processing engine. However, the issue of ensuring that the combinations of events provide the system with the correct combination of information is often left to the developer to analyze. We argue that analyzing correctness of event composition is a complex task that needs tool support. In this paper we present a novel development tool for specifying composition of events with time constraints. One key feature of our tool is to automatically transform composite events for real-time systems into a timed automaton representation. The timed automaton representation allow us to check for design errors, for example, whether the outcome of combining events with different operators in different consumption policies is consistent with the requirement specification
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| 7. |
- Ericsson, AnnMarie, et al.
(författare)
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Event in Active Databases
- 2009
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Ingår i: Encyclopedia of Database Systems. - Boston, MA : Springer Science+Business Media B.V.. - 9780387496160 - 9780387355443 - 9780387399409 ; , s. 1044-1045
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 8. |
- Ericsson, Anna, et al.
(författare)
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Functional characterization of the CCL25 promoter in small intestinal epithelial cells suggests a regulatory role for caudal-related homeobox (Cdx) transcription factors
- 2006
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Ingår i: Journal of Immunology. - : American Association of Immunologists. - 0022-1767 .- 1550-6606. ; 176:6, s. 3642-3651
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Tidskriftsartikel (refereegranskat)abstract
- The chemokine CCL25 is selectively and constitutively expressed in the small intestinal epithelium and plays an important role in mediating lymphocyte recruitment to this site. In this study, we demonstrate that CCL25 expression in murine small intestinal epithelial cells is independent of signaling through the lymphotoxin 0 receptor and is not enhanced by inflammatory stimuli, pathways involved in driving the expression of most other chemokines. We define a transcriptional start site in the CCL25 gene and a region -141 to -5 proximal of exon 1 that is required for minimal promoter activity in the small intestinal epithelial cell lines, MODE-K and mICc12. These cell lines expressed far less CCL25 mRNA than freshly isolated small intestinal epithelial cells indicating that they are missing important factors driving CCL25 expression. The CCL25 promoter contained putative binding sites for,the intestinal epithelial-associated Caudal-related homeobox (Cdx) transcription factors Cdx-1 and Cdx-2, and small intestinal epithelial cells but not MODE-K and mICc12 cells expressed Cdx-1 and Cdx-2. EMSA analysis demonstrated that Cdx proteins were present in nuclear extracts from freshly isolated small intestinal epithelial cells but not in MODE-K or mICcl2 cells, and bound to putative Cdx sites within the CCL25 promoter. Finally, cotransfection of MODE-K cells with Cdx transcription factors significantly increased CCL25 promoter activity as well as endogenous CCL25 mRNA levels. Together these results demonstrate a unique pattern of regulation for CCL25 and suggest a role for Cdx proteins in regulating CCL25 transcription.
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| 9. |
- Ericsson, AnnMarie, et al.
(författare)
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REX, the Rule and Event eXplorer
- 2007
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Ingår i: DEBS '07. - New York : Association for Computing Machinery (ACM). - 9781595936653 ; , s. 71-74
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Konferensbidrag (refereegranskat)abstract
- Complex Event Processing (CEP) is a technology with support for matching patterns in a cloud or streams of events in order to support detection of specific combinations of event occurrences. A clever specification of event patterns may, for example, detect fraud attempts in a banking system, fire an alarm in response to hazardous situations in a control system or report suspicious customer behavior.Several CEP engines have support for graphically modelling applications as well as perform tests and provide execution traces to verify the application behavior. We argue that it is beneficial to complement testing with formal verification in order to detect errors in early stages of development.In this paper, we present the research prototype tool REX. REX is built as a loosely coupled front end to the timed-automata CASE tool UPPAAL. CEP applications and application specific properties can be specified in REX. To support formal verification, REX seamlessly transforms the CEP application together with the specified properties to the timed automata CASE tool UPPAAL where the properties are verified by the model-checker provided by UPPAAL.
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| 10. |
- Ericsson, AnnMarie, et al.
(författare)
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Seamless Formal Verification of Complex Event Processing Applications
- 2007
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Ingår i: DEBS '07. - New York : Association for Computing Machinery (ACM). - 9781595936653 ; , s. 50-61, s. 50-61
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Konferensbidrag (refereegranskat)abstract
- Despite proven successful in previous projects, the use of formal methods for enhancing quality of software is still not used in its full potential in industry. We argue that seamless support for formal verification in a high-level specification tool enhances the attractiveness of using a formal approach for increasing software quality.Commercial Complex Event Processing (CEP) engines often have support for modelling, debugging and testing CEP applications. However, the possibility of utilizing formal analysis is not considered.We argue that using a formal approach for verifying a CEP system can be performed without expertise in formal methods. In this paper, a prototype tool REX is presented with support for specifying both CEP systems and correctness properties of the same application in a high-level graphical language. The specified CEP applications are seamlessly transformed into a timed automata representation together with the high-level properties for automatic verification in the model-checker UPPAAL.
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| 11. |
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| 12. |
- Ericsson, AnnMarie, et al.
(författare)
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Verification of an industrial rule-based manufacturing system using REX
- 2008
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Ingår i: Proceedings of the 1st iCEP08 Workshop onComplex Event Processing for the Future Internet Vienna, Austria, September 28th, 2008. - : CEUR-WS.org. ; , s. 1-10
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Konferensbidrag (refereegranskat)abstract
- Formal methods are not used in their full potential for enhancing software quality in industry. We argue that seamless support in a high-level specification tool is a viable way to provide system designers with powerful and paradigm specific formal verification techniques. Event condition action (ECA) rules can be used to model and implement reactive behavior in, for example, the semantic web. Independently of target system, the behavior of rule-based systems are known to be hard to analyze. The REX tool is a rule-based front-end to the timed automata CASE-tool Uppaal. The model-checker in Uppaal is used by REX enabling seamless support for model-checking rule-based specifications in REX.This paper presents experiences from modeling and verifying a system of industrial complexity as interacting rules using EX. We conclude that repeatedly performing normal analysis when constructing a system with interacting rules is a viable way of coping with the complexity of the model. Additionally, we present an implemented algorithm for optimizing the model to reduce the effect of state-space explosion.
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| 13. |
- Ericsson, Mikael, 1975-, et al.
(författare)
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A look at the optimization of robot welding speed based on process modelling
- 2007
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Ingår i: Welding Journal. - 0043-2296. ; 86:8, s. 238-244
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Tidskriftsartikel (refereegranskat)abstract
- Simulation tools to search for optimal process parameters are of great interest to reduce the number of experiments and thereby reduce cost and production time. In this paper, robot simulation has been used in combination with finite element simulations to optimize robot speed in order to minimize distortion while keeping complete joint penetration. In an earlier work performed by the authors, a finite element model was developed to predict heat transfer and residual stresses of parts with complex shapes. An interface between a robot simulation model and a finite element analysis model was also constructed. In this paper, an iterative method for robot speed optimization has been developed using MATLAB. The algorithm is designed to maintain complete joint penetration while maximizing productivity by utilizing the fastest weld speed. The method makes it possible to optimize the heat input to the component and thereby minimize component deformation for parts with complex shapes. The system was evaluated on stainless steel plates with varying thicknesses. Robot weld paths were defined off line and automatically downloaded to the finite element software where the optimization was performed. Simulations and experimental validations are presented.
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| 14. |
- Ericsson, Mikael, 1975-, et al.
(författare)
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Off-line programming of robots for metal deposition
- 2005
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Ingår i: Trends in welding research. - 0871708426 ; , s. 629-634
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Metal Deposition (MD) is a rapid prototyping technique to build parts by depositing metal in a required fashion. When a complex-shaped part is to be built, a simulation tool is needed to define robot trajectories. Three different simulation-based methods for robot trajectory generation are introduced and compared in this study. The methods are; reversed milling, adapted rapid prototyping and application programming in a computer aided robotics software. All methods were shown capable of creating robot paths for complex shapes, with the CAR software approach being the most flexible. Using this method, the geometry to be built is automatically sliced into layers and a robot path is automatically generated. The method was tentatively evaluated and appears to provide a powerful technique in the design and optimisation of robot paths for MD. Experiments showed that it is possible to manufacture fully dense parts using an Nd-Yag laser.
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| 15. |
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| 16. |
- Ericsson, Mikael
(författare)
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Simulation of robot paths and heat effects in welding
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The objective of this thesis is to develop a simulation tool and a method by which robot trajectories, temperature histories, residual stresses and distortion can be analysed and optimized off-line. This was performed by integrating robot simulation software with finite element analysis software. A special interface was created which facilitated information exchange between the two software programs. To validate the method comparisons were made between simulation results and measurements during real welding. The method was used to program welding trajectories, both for planar plates and for parts with complex shapes. The welding trajectories were downloaded to the finite element analysis software where temperature and residual stress prediction were performed. Good agreement was found between the programmed robot trajectory, and the actual trajectory, necessitating only minor adjustments. Temperature measurements were performed using both thermocouples and infrared imaging. Good agreement was also found between the results using these two methods, as well as between predicted and measured temperatures. Predicted residual stress distributions were compared with neutron diffraction measurements and fair agreement was found. A specified software architecture was developed which allowed full time synchronization between different simulation systems. Finally, weld velocity optimization was performed through a developed algorithm making it possible to minimize distortion. The research conducted in the present work indicates that the models and computer programs that were developed could be combined to create powerful tools for the evaluation and optimisation of welding processes.
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| 17. |
- Ericsson, Mikael, 1975-, et al.
(författare)
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Three dimensional simulation of robot path, heat transfer and residual stresses of a welded part with complex geometry
- 2005
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Ingår i: International jourrnal for the joining of materials. - 0905-6866. ; 17:2, s. 42-51
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Tidskriftsartikel (refereegranskat)abstract
- In this article a simulation system is presented that combines computer aided robotics software used to define the welding operation, with a finite element model that predicts temperature-time histories and residual stress distributions for welding applications. The objective is to develop a tool for engineering processes in which robot trajectories and welding process parameters can be optimized off-line on parts with complex geometries. The system was evaluated on a stainless steel gas turbine component. Temperature dependent properties and phase change were included in the analysis. The turbine component was welded using an in-house TIG welding cell. The assumptions and principles that underpin the modeling techniques are presented together with predicted temperature histories, residual stresses, and fixture forces. Predicted residual stresses were compared with neutron diffraction measurements.
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| 18. |
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| 19. |
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| 20. |
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| 21. |
- Li, Lu, 1964, et al.
(författare)
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Epigallocatechin gallate increases the formation of cytosolic lipid droplets and decreases the secretion of apoB-100 VLDL
- 2006
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Ingår i: J Lipid Res. - 0022-2275. ; 47:1, s. 67-77
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Tidskriftsartikel (refereegranskat)abstract
- Epigallocatechin gallate (EGCG) increases the formation of cytosolic lipid droplets by a mechanism that is independent of the rate of triglyceride biosynthesis and involves an enhanced fusion between lipid droplets, a process that is crucial for their growth in size. EGCG treatment reduced the secretion of both triglycerides and apolipoprotein B-100 (apoB-100) VLDLs but not of transferrin, albumin, or total proteins, indicating that EGCG diverts triglycerides from VLDL assembly to storage in the cytosol. This is further supported by the observed increase in both intracellular degradation of apoB-100 and ubiquitination of the protein (indicative of increased proteasomal degradation) in EGCG-treated cells. EGCG did not interfere with the microsomal triglyceride transfer protein, and the effect of EGCG on the secretion of VLDLs was found to be independent of the LDL receptor. Thus, our results indicate that EGCG promotes the accumulation of triglycerides in cytosolic lipid droplets, thereby diverting lipids from the assembly of VLDL to storage in the cytosol. Our results also indicate that the accumulation of lipids in the cytosol is not always associated with increased secretion of VLDL.
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| 22. |
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| 23. |
- Nilsson, Jim, 1983-, et al.
(författare)
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Virtual Machine Vision in Computer Aided Robotics
- 2009
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Ingår i: Emerging Technologies & Factory Automation. - 9781424427277 ; , s. 1-8
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Konferensbidrag (refereegranskat)abstract
- In this paper a concept for Virtual Machine Vision is proposed using a commercial Computer Aided Robotics software called RobCad. The system utilizes ideal virtual cameras and lights for the simulation of a real vision system. Sensory data is sent to a vision software for data analysis. The Virtual Machine Vision together with the simulation model can be used to offline programming of a vision system. Experiments have been performed by capturing images of a test piece both in the virtual environment and in a physical experimental rig. To evaluate the concept, image analysis has been performed on these images using the same vision software. The results from the vision analysis of both the virtual and the real images are compared and show good agreement. The proposed system seems to be very promising and further development is ongoing.
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| 24. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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3D-Scanning for Weld Distortion Measuring
- 2006
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Ingår i: Instrumentation and Measurement Technology Conference, 2006. IMTC 2006. Proceedings of the IEEE. - : IEEE conference proceedings. - 0780393600 - 0780393597 ; , s. 2132-2137
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Konferensbidrag (refereegranskat)abstract
- Optical three dimensional scanning for weld distortion measurements have been performed for validation, inspection, general visualization and documentation of a robotized welding process. The planning, preparing and processing of the weld is done in a simulation-based concept where computer aided robotics software simulations are integrated with finite element analysis simulations with the objective to reduce global geometrical deformation during welding. The off-line programmed robot paths were used as an input for finite element calculations of temperature fields and distortion in the work piece. In order to validate the finite element model 3D-scannings have been performed before and after every single welding sequence. This paper describes a validation experiment with non-contact measurements of weld distortion and discusses limitations in optical 3D-scanning techniques used for this purpose
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| 25. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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Integration of finite element analysis and computer aided robotics for advanced programming of robotized welding
- 2009
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Ingår i: ASM Proceedings of the International Conference: Trends in Welding Research. - : ASM International. - 9781615030026 ; , s. 454-460
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Konferensbidrag (refereegranskat)abstract
- This paper describes a promising approach where finite element analysis is combined with computer aided robotics in off-line programming of advanced robotized welding. Finite element analysis is used to find an optimized weld power signal based on weld trajectories obtained from computer aided robotic simulations. The weld power signal is calculated by applying feedback control in the finite element simulation. This optimization ensures a full penetration weld while the total specific thermal energy input is minimized in order to mitigate unwanted residual stress and distortion. The objective with this approach is to support the design of robotized welding and significantly reduce the number of costly trials in physical implementations. The relevance of this paper is a useful method for off-line optimization of robot trajectories and varying process parameters.
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| 26. |
- Sikström, Fredrik, 1971-, et al.
(författare)
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Tools for simulation based fixture design to reduce deformation in advanced fusion welding
- 2008
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Ingår i: Intelligent Robotics and ApplicationsLecture Notes in Computer Science Volume 5315, 2008. - Berlin, Heidelberg : Springer. ; , s. 398-407
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Konferensbidrag (refereegranskat)abstract
- The traditional fusion welding and fixture simulations are performed using advanced finite element simulation tools, commonly used are e.g. MSC.Marc, ANSYS, ABACUS and COMSOL Multiphysics. These simulations are made one at a time and separately due to heavy calculation load for each case. Such an approach does not give a full description of the integrated work piece and fixture behaviour. We propose a strategy to decrease the computational time and solve the problem accurately enough for industrial needs. Focus of the simulation result is on residual deformation. The work piece is a simplified component composed by metal sheets, and rigid and loose clamping was investigated. Simulation results give the size of forces and deformations in the clamped edge. Deformation measurements are performed using 3D-scanning of the work piece after cooling and released from fixture, same situation as in the FE-simulations. The proposed strategy has shown to be useful and is industrially competitive due to reduced engineering manpower, computation time, and need for practical experiments. The strategy is to use full off-line programming where computer aided robotics for weld sequencies is integrated with finite element modelling in order to obtain weld parameters and fixture design.
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| 27. |
- Wingkvist, Anna, 1976-
(författare)
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Understanding Scalability and Sustainability in Mobile Learning : A Systems Development Framework
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The rapid development of mobile technologies combined with access to content almost everywhere and every time allows people to experience new situations regarding learning in a wide variety of situations. Mobile learning brings the promise of learning "on the move" by allowing learners to take control over time and space, thus making learning "more natural". The field of mobile learning has rapidly evolved in the last ten years and many initiatives have been conducted worldwide. However, research results indicate that few of these efforts have produced any lasting outcomes. It is evident that these initiatives are faced with inherently complex settings and that the outcomes might not live up to their prom- ises; will not be adopted and, hence, will not become sustainable. Many of the complex issues faced by mobile learning initiatives are similar to those faced by the development of information systems. This latest statement suggests that an improved development practice might hold one piece of the key to sustainable mobile learning. The aim of the research presented in this thesis is to investigate the relation between information systems development practice and mobile learning development; and if methods and models originated within information systems development can be used to strengthen mobile learning initiatives. In order to investigate this relation, this thesis studies several mobile learning initiatives with a particular focus on how and why development and research was initiated and conducted. Concepts found in mobile learning practices are strengthened by providing a theoretical perspective with roots in information systems development. The outcomes of the studies presented in this thesis indicate that the development practice of mobile learning initiatives can be redefined in order to achieve more sustainable results. The core of this thesis consists of eight peer-reviewed scientific publications that have been presented at different international conferences. Five of the papers explore the field of mobile learning and its practice while the other three publications present the central ideas that serve as the basis for the proposed framework, how it has been developed, and the motivations behind its creation. The main contribution of this thesis is a novel development framework aimed at researchers and practitioners in the field of mobile learning. The framework defines the life-cycle of a mobile learning initiative and identifies the importance of emphasizing the concepts of scalability and sustainability during the development process. This may be a way to reduce the complexity inherent to mobile learning and its settings, and a means to improve the outcomes of coming mobile learning initiatives in terms of long lasting usable results.
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