| 1. |
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| 2. |
- Holzgraefe, Bernhard, et al.
(författare)
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Does permissive hypoxaemia during extracorporeal membrane oxygenation cause long-term neurological impairment? : A study in patients with H1N1-induced severe respiratory failure
- 2017
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Ingår i: European Journal of Anaesthesiology. - 0265-0215 .- 1365-2346. ; 34:2, s. 98-103
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The Extracorporeal Life Support Organisation accepts permissive hypoxaemia in adult patients during extracorporeal membrane oxygenation (ECMO). The neurological long-term outcome of this approach has not yet been studied.OBJECTIVES: We investigated the prevalence of brain lesions and cognitive dysfunction in survivors from the Influenza A/H1N1 2009 pandemic treated with permissive hypoxaemia during ECMO for severe acute respiratory distress syndrome (ARDS). Our hypothesis was that this method is reasonable if tissue hypoxia is avoided.DESIGN: Long-term follow-up study after ECMO.SETTING: Karolinska University Hospital, Sweden, from October 2012 to July 2013.PATIENTS: Seven patients treated with ECMO for severe influenza A/H1N1-induced ARDS were studied 3.2 years after treatment. Blood lactate concentrations were used as a surrogate for tissue oxygenation.INTERVENTIONS: Neurocognitive outcome was studied with standardised cognitive tests and MRI of the brain.MAIN OUTCOME MEASURES: Cognitive functioning and hypoxic brain lesions after permissive hypoxaemia during ECMO. The observation period was the first 10 days of ECMO or the entire treatment period if shorter than 10 days.RESULTS: Eleven of 13 patients were still alive 3 years after ECMO. We were able to contact seven of these patients (mean age 31 years), who all agreed to participate in this study. Mean +/- SD peripherally measured arterial saturation during the observation period was 79 +/- 10%. Full-scale Intelligence Quotient was within one standard deviation or above from the mean of a healthy population in five patients, and was 1.5 SD below the mean in one patient. In one other patient, it could not be determined because of a lack of formal education. Memory functioning was normal in all patients. MRI showed no changes related to cerebral hypoxia.CONCLUSIONS: Permissive hypoxaemia during ECMO might not negatively affect long-term cognitive outcome if adequate organ perfusion is maintained.
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| 3. |
- Larsson, Carl, 1997, et al.
(författare)
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Effects of lithium insertion induced swelling of a structural battery negative electrode
- 2023
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Ingår i: Composites Science and Technology. - 0266-3538. ; 244
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Tidskriftsartikel (refereegranskat)abstract
- Structural battery composites fall under the category multifunctional materials with the ability to simultaneously store electrical energy and carry mechanical load. While functioning as the negative electrode, the carbon fibres also act as mechanical reinforcement. Lithium ion insertion in the carbon fibres is accompanied by a large radial expansion of 6.6 % and an axial expansion of 0.85 % of the fibres. Furthermore, the elastic moduli of the carbon fibres are significantly affected by the insertion of lithium. Current structural battery modelling approaches do not consider these features. In this paper, we investigate the effect of lithium insertion in carbon fibres on the structural electrode mechanical properties by developing a computational model considering finite strains and lithium concentration dependent fibre moduli. The computational model enables representation of morphological change, whereby, features such as internal stress state, homogenized tangent stiffness and effective expansion of the electrode caused by carbon fibre lithiation can be predicted. The adopted finite strain formulation allows for consistent consideration of measurement data at varying state of lithiation. The significance of adopting the finite strain formulation is also shown numerically. Finally, by implementing a novel approach to homogenized stress-free expansion, it is shown that the computed expansion of the structural electrode follows a similar trend to what is observed from experiments.
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| 4. |
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| 5. |
- Larsson, Malin, 1983-, et al.
(författare)
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A new ultrasound-based approach to visualize target specific polymeric contrast agent
- 2011
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Ingår i: 2011 IEEE International Ultrasonics Symposium (IUS). - : IEEE. - 9781457712524 ; , s. 1626-1629
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Konferensbidrag (refereegranskat)abstract
- There are advantages of using a polymeric shelled contrast agent (CA) during ultrasound imaging instead of lipid shelled CA, e.g. particles can be attached to the surface, which enables an introduction of antibodies to the surface making the CA target specific. For this application it is essential to have a sensitive imaging technique suitable for polymeric CA. However, previously presented results have indicated difficulties in visualizing polymeric CA with commercially available contrast algorithms. Therefore a new subtraction algorithm (SA), was developed that define the difference between contrast and reference images. The aim of this study was to evaluate the response from a polymeric CA, when using the SA and compare it with existing contrast algorithms. Moreover, the possibility to detect a thin layer of CA was tested using the SA.Ultrasound short-axis images of a tissue-mimicking vessel phantom with a pulsating flow were obtained using a GE Vivid7 system (M12L) and a Philips iE33 system (S5-1). Repeated (n=91) contrast to tissue ratios (CTR) calculated at various mechanical index (MI) using the contrast algorithms pulse inversion (PI), power modulation (PM) and SA at a concentration of 105microbubbles/ml.The developed SA showed improvements in CTR compared to existing contrast algorithms. The CTRs were -0.99 dB ± 0.67 (MI 0.2), 9.46 dB ± 0.77 (MI 0.4) and 2.98 dB ± 0.60 (MI 0.8) with PI, 8.17 dB ± 1.15 (MI 0.2), 15.60 dB ± 1.29 (MI0.4) and 11.60 dB ± 0.73 (MI 0.8) with PM and 14.97 dB ± 3.97 (MI 0.2), 20.89 dB ± 3.54 (MI 0.4) and 21.93 dB ± 4.37 (MI 0.8) with the SA. In addition to this, the layer detection, when using the SA was successful.
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| 6. |
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| 7. |
- Larsson, Malin K., et al.
(författare)
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Endocardial border delineation capability of a multimodal polymer-shelled contrast agent
- 2014
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundA novel polymer-shelled contrast agent (CA) with high mechanical and chemical stability was recently developed [1]. In excess to its ultrasound properties, it also supports targeted and multimodal imaging [2-4]. Even though these new possibilities have the potential to lead to new methodologies and approaches for non-invasive diagnosis, it is important that the fundamental diagnostic features in contrast-enhanced ultrasound are preserved. The aim of this study was therefore to examine the clinical use of the polymer-shelled CA by analyzing the left ventricular endocardial border delineation capability in a porcine model. In addition, physiological effects due to CA injections were studied.MethodsThe endocardial border delineation capability was assessed in a comparative study, which included three doses (1.5 ml, 3 ml and 5 ml, [5x108 MBs/ml]) of the polymer-shelled CA and the commercially available CA SonoVue® (1.5 ml, [2-5x108 MBs/ml]). Ultrasound images of the left ventricle were evaluated manually by blinded observers (n=3) according to a 6-segment model, in which each segment was graded as 0=not visible, 1=barely visible or 2=well visible, as well as semi-automatically by a segmentation software. Furthermore, duration of clinically useful contrast enhancement and changes in physiological parameters were evaluated.ResultsFor the highest dose of the polymer-shelled CA, the obtained segment scores, time for clinically sufficient contrast enhancement and semi-automatic delineation capability were comparable to SonoVue®. Moreover, neither dose of the polymer-shelled CA did affect the physiological parameters.ConclusionThis study demonstrated that the polymer-shelled CA can be used in contrast-enhanced diagnostic imaging without influence on major physiological parameters.
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| 8. |
- Larsson, Malin K., et al.
(författare)
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Endocardial border delineation capability of a novel multimodal polymer-shelled contrast agent
- 2014
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Ingår i: Cardiovascular Ultrasound. - : Springer Science and Business Media LLC. - 1476-7120. ; 12, s. 24-
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Tidskriftsartikel (refereegranskat)abstract
- Background: A novel polymer-shelled contrast agent (CA) with multimodal and target-specific potential was developed recently. To determine its ultrasonic diagnostic features, we evaluated the endocardial border delineation as visualized in a porcine model and the concomitant effect on physiological variables. Methods: Three doses of the novel polymer-shelled CA (1.5 ml, 3 ml, and 5 ml [5 x 10(8) microbubbles (MBs)/ml]) and the commercially available CA SonoVue (1.5 ml [2-5 x 10(8) MBs/ml]) were used. Visual evaluations of ultrasound images of the left ventricle were independently performed by three observers who graded each segment in a 6-segment model as either 0 = not visible, 1 = weakly visible, or 2 = visible. Moreover, the duration of clinically useful contrast enhancement and the left ventricular opacification were determined. During anesthesia, oxygen saturation, heart rate, and arterial pressure were sampled every minute and the effect of injection of CA on these physiological variables was evaluated. Results: The highest dose of the polymer-shelled CA gave results comparable to SonoVue. Thus, no significant difference in the overall segment score distribution (2-47-95 vs. 1-39-104), time for clinically sufficient contrast enhancement (20-40 s for both) and left ventricular overall opacification was found. In contrast, when comparing the endocardial border delineation capacity for different regions SonoVue showed significantly higher segment scores for base and mid, except for the mid region when injecting 1.5 ml of the polymer-shelled CA. Neither high nor low doses of the polymer-shelled CA significantly affected the investigated physiological variables. Conclusions: This study demonstrated that the novel polymer-shelled CA can be used in contrast-enhanced diagnostic imaging without influence on major physiological variables.
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| 9. |
- Larsson, Malin, et al.
(författare)
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Visualization of multimodal polymer-shelled contrast agents using ultrasound contrast sequences : an experimental study in a tissue mimicking flow phantom
- 2013
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Ingår i: Cardiovascular Ultrasound. - : Springer Science and Business Media LLC. - 1476-7120. ; 11, s. 33-
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Tidskriftsartikel (refereegranskat)abstract
- Background: A multimodal polymer-shelled contrast agent (CA) with target specific potential was recently developed and tested for its acoustic properties in a single element transducer setup. Since the developed polymeric CA has different chemical composition than the commercially available CAs, there is an interest to study its acoustic response when using clinical ultrasound systems. The aim of this study was therefore to investigate the acoustic response by studying the visualization capability and shadowing effect of three polymer-shelled CAs when using optimized sequences for contrast imaging. Methods: The acoustic response of three types of the multimodal CA was evaluated in a tissue mimicking flow phantom setup by measuring contrast to tissue ratio (CTR) and acoustic shadowing using five image sequences optimized for contrast imaging. The measurements were performed over a mechanical index (MI) range of 0.2-1.2 at three CA concentrations (10(6), 10(5), 10(4) microbubbles/ml). Results: The CTR-values were found to vary with the applied contrast sequence, MI and CA. The highest CTR-values were obtained when a contrast sequence optimized for higher MI imaging was used. At a CA concentration of 106 microbubbles/ml, acoustic shadowing was observed for all contrast sequences and CAs. Conclusions: The CAs showed the potential to enhance ultrasound images generated by available contrast sequences. A CA concentration of 106 MBs/ml implies a non-linear relation between MB concentration and image intensity.
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| 10. |
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| 11. |
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| 12. |
- Widman, Erik, et al.
(författare)
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Feasibility of shear wave elastography for plaque characterization
- 2014
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Ingår i: IEEE International Ultrasonics Symposium, IUS. - 9781479970490 ; , s. 1818-1821
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Konferensbidrag (refereegranskat)abstract
- Determining plaque vulnerability is critical when selecting the most suitable treatment for patients with atherosclerotic plaque in the common carotid artery and quantitative characterization methods are needed. In this study, shear wave elastography (SWE) was used to characterize soft plaque mimicking inclusions in three atherosclerotic arterial phantoms by using phase velocity analysis in a static environment. The results were validated with axial tensile mechanical testing (MT). SWE measured a mean shear modulus of 5.8 ± 0.3 kPa and 25.0 ± 1.2 kPa versus 3.0 kPa and 30.0 kPa measured by mechanical testing in the soft plaques and phantom walls respectively. The results show good agreement between MT and SWE for both the plaque and phantom wall.
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| 13. |
- Adelmann, Kenneth, et al.
(författare)
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Språkutveckling, medier och demokrati
- 2014
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Ingår i: Medie- och informationskunnighet i Norden. - Göteborg : Nordicom. - 9789186523886 ; , s. 117-129
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 14. |
- Aggerholm, Kenneth, et al.
(författare)
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Practising movement at home : An idea for meaningful remote teaching in physical education
- 2021
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Ingår i: Idrottsforum.org/Nordic sport science forum. - : Malmö University. - 1652-7224.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Since March 2020, most physical education (PE) teachers in Scandinavia have faced the challenges of remote teaching. Homeschooling has perhaps been particularly challenging for PE teachers compared to other teachers, given the essential role of bodily contact, interaction, social negotiations, game playing and shared expressions in PE (Varea and González-Calvo, 2020).Having worked with covid conditions for a year now, we trust that teachers have worked out various solutions that, we hope, are relevant and meaningful for the students. At the same time, both from our personal experiences and early research findings (Mercier et al. 2021), it appears that PE teachers have largely provided students with physical activity and fitness training during the pandemic.In this short text, we want to share an idea for a concrete alternative to fitness exercises, which, although important, is only one part of the PE curriculum. It springs from a pedagogical model we outlined in a double article from 2018, which focuses on practising. Practising, which in German is üben and in the Scandinavian languages øve/öva, is, briefly put, a form of activity in which you seek to improve some part of yourself through repeated efforts.Recently, one of our colleagues, Dillon Landi, made us aware that this practising model is particularly relevant for teaching during the pandemic. While we did not have remote teaching in mind when we outlined the model, we realise now that it could be a relevant way of coping with the current situation. It can, we believe, guide how teachers can facilitate movement activities for students at home that are both meaningful and educationally relevant.In the following, we will describe what remote teaching with a focus on practising might look like. We hope it can inspire teaching methods that add to the list of pedagogical options available for teachers during the pandemic.
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| 15. |
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| 16. |
- Aggestam, Emil, 1992, et al.
(författare)
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Numerical model reduction with error control in computational homogenization of transient heat flow
- 2017
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier BV. - 0045-7825. ; 326, s. 193-222
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Tidskriftsartikel (refereegranskat)abstract
- Numerical Model Reduction (NMR) is exploited for solving the finite element problem on a Representative Volume Element (RVE) that arises from the computational homogenization of a model problem of transient heat flow. Since the problem is linear, an orthogonal basis is obtained via the classical method of spectral decomposition. A symmetrized version of the space–time variational format is adopted for estimating the error from the model reduction in (i) energy norm and in (ii) given Quantities of Interest. This technique, which was recently developed in the context of the (non-selfadjoint) stationary diffusion–convection problem, is novel in the present context of NMR. By considering the discrete, unreduced, model as exact, we are able to obtain guaranteed bounds on the error while using only the reduced basis and with minor computational effort. The performance of the error estimates is demonstrated via numerical results, where the subscale is modeled in both one and three spatial dimensions.
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| 17. |
- Al-Mudhaffar, Azhar, et al.
(författare)
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Ny ekvation för beräkning av uppställningsbehov i bussterminaler
- 2024
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Ingår i: Sammanställning av referat från Transportforum 2024. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 106-107
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Behov för uppställningsplatser (UP) kan delas in i tre olika kategorier; reglering, paus och rast. Reglering avser buss som står parkerad med förare ombord för att vänta in nästa körtid. Tidsregleringen pågår normalt upp till 15 minuter. Paus och rast avser parkerad buss utan förare, i nära anslutning till paus-/rastlokal. En kortare paus är normalt ≥ 10 minuter och en planerad rast ≥30 minuter. Flera bussterminaler i Stockholmsregion har brist på påstigningshållplatser och uppställningsplatser, vilket är ett resultat av intresset för att minimera ytan eftersom bussterminaler vanligtvis upptar attraktiv mark nära stadskärnor. Metoder för beräkning av framtidsbehov är inte bristfria och behöver utvecklas för att säkerställa kapaciteten med optimal markanvändning. En befintlig metod som används av Trafikförvaltningen uppskattar att den erforderliga UP är lika med antalet busslinjer med turtäthet upp till 8 avgångar/tim. Linjer med högre turtäthet behöver mer än en plats. Denna metod är mer lämplig med linjer som har 6-8 avg./tim, men för lägre turtäthet resulterar den i behovsöverskattning. En ekvation i “Transit Capacity and Quality of Service Manual TCQSM, Report 165.” antar att UP (Nberths) för en linje beror på uppehållstiden (tlayover) och tidsavståndet mellan på följande bussar (theadway): Nberths = 1.2*(tlayover/theadway) Denna metod kräver data om tidsavstånd som är svårt att uppskatta vid framtids bussterminal i Stockholmsregion eftersom bussarna, efter uppehållstiden, inte alltid återvänder som samma linje. Därför finns det ett behov av att utveckla en användbar metod för att uppskatta antalet UP med tillgängliga data.Metoden har innefattat:LitteraturstudierFältobservationer av beläggning i uppställningsplatserWorkshops och intervjuer med trafikutövareFramtagande av ny linjär ekvation UP=a+(avg./tim)/bTillämpning och utvärderingJämförelse av resultat med andra metoderDiskussion och beslut om metoden i intern terminalgrupp.Den utvecklade metoden är inte applicerbar i alla regioner utan kalibrering eftersom den är anpassade till förhållande i Stockholmsregion. Arbetet med att utforma den mest optimala och effektiva bussterminalen kommer att fortsätta i takt med att metoderna blir bättre på att identifiera och fastställa de uppställningsplatser som behövs. Detta är ett arbete där teoretiska studier kommer att kombineras med erfarenhet och kunskapsöverföring.
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| 18. |
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| 19. |
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| 20. |
- Andersson, Richard, et al.
(författare)
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One algorithm to rule them all? : An evaluation and discussion of ten eye movement event-detection algorithms
- 2017
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Ingår i: Behavior Research Methods. - : Springer Science and Business Media LLC. - 1554-3528. ; 49:2, s. 616-637
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Tidskriftsartikel (refereegranskat)abstract
- Almost all eye-movement researchers use algorithms to parse raw data and detect distinct types of eye movement events, such as fixations, saccades, and pursuit, and then base their results on these. Surprisingly, these algorithms are rarely evaluated. We evaluated the classifications of ten eye-movement event detection algorithms, on data from an SMI HiSpeed 1250 system, and compared them to manual ratings of two human experts. The evaluation focused on fixations, saccades, and post-saccadic oscillations. The evaluation used both event duration parameters, and sample-by-sample comparisons to rank the algorithms. The resulting event durations varied substantially as a function of what algorithm was used. This evaluation differed from previous evaluations by considering a relatively large set of algorithms, multiple events, and data from both static and dynamic stimuli. The main conclusion is that current detectors of only fixations and saccades work reasonably well for static stimuli, but barely better than chance for dynamic stimuli. Differing results across evaluation methods make it difficult to select one winner for fixation detection. For saccade detection, however, the algorithm by Larsson, Nyström and Stridh (IEEE Transaction on Biomedical Engineering, 60(9):2484–2493,2013) outperforms all algorithms in data from both static and dynamic stimuli. The data also show how improperly selected algorithms applied to dynamic data misestimate fixation and saccade properties.
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| 21. |
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| 22. |
- Aramrattana, Maytheewat
(författare)
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Modelling and Simulation for Evaluation of Cooperative Intelligent Transport System Functions
- 2016
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Future vehicles are expected to be equipped with wireless communication technology, that enables them to be “connected” to each others and road infrastructures. Complementing current autonomous vehicles and automated driving systems, the wireless communication allows the vehicles to interact, cooperate, and be aware of its surroundings beyond their own sensors’ range. Such sys- tems are often referred to as Cooperative Intelligent Transport Systems (C-ITS), which aims to provide extra safety, efficiency, and sustainability to transporta- tion systems. Several C-ITS applications are under development and will require thorough testing and evaluation before their deployment in the real-world. C- ITS depend on several sub-systems, which increase their complexity, and makes them difficult to evaluate.Simulations are often used to evaluate many different automotive applications, including C-ITS. Although they have been used extensively, simulation tools dedicated to determine all aspects of C-ITS are rare, especially human factors aspects, which are often ignored. The majority of the simulation tools for C-ITS rely heavily on different combinations of network and traffic simulators. The human factors issues have been covered in only a few C-ITS simulation tools, that involve a driving simulator. Therefore, in this thesis, a C-ITS simulation framework that combines driving, network, and traffic simulators is presented. The simulation framework is able to evaluate C-ITS applications from three perspectives; a) human driver; b) wireless communication; and c) traffic systems.Cooperative Adaptive Cruise Control (CACC) and its applications are chosen as the first set of C-ITS functions to be evaluated. Example scenarios from CACC and platoon merging applications are presented, and used as test cases for the simulation framework, as well as to elaborate potential usages of it. Moreover, approaches, results, and challenges from composing the simulation framework are presented and discussed. The results shows the usefulness of the proposed simulation framework.
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| 23. |
- Arandia, Kenneth Gacutno, 1990, et al.
(författare)
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Fouling characteristics of microcrystalline cellulose during cross-flow microfiltration: Insights from fluid dynamic gauging and molecular dynamics simulations
- 2023
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Ingår i: Journal of Membrane Science. - : Elsevier BV. - 1873-3123 .- 0376-7388. ; 669
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Tidskriftsartikel (refereegranskat)abstract
- The fouling behaviour of microcrystalline cellulose (MCC) particles on polyethersulfone (PES) membranes was investigated using fluid dynamic gauging (FDG) and molecular dynamics (MD) simulations. Experimental cross-flow microfiltration (MF) of a dilute MCC suspension at 400 mbar transmembrane pressure using 0.45 μm PES membranes revealed an estimated fouling layer thickness of 616 ± 5 μm for both fouled and re-fouled membranes at an applied shear stress of 37 ± 2 Pa. A decline in pure water flux was observed after each membrane cleaning and flushing procedure, indicating that highly resilient layers were formed close to the membrane surface. A possible explanation for the formation of resilient cellulose layers was obtained through MD simulations of the free energy profiles, which predicted deep energy minima at close interparticle separations of the cellulose–cellulose and cellulose–PES systems. The consequence of this energy minima is that attractive and repulsive forces are in balance at a specific distance between the particles, suggesting high binding energy at close interparticle distances. This implies that a certain force is needed to remove the layer or redisperse the cellulose particles. MD simulations also suggested that contributions made by repulsive hydration forces negatively influenced the adsorption of cellulose particles onto the PES membrane. These results highlight how experimental FDG measurements, when complemented with MD simulations, can provide insights into the fouling behaviour of an organic model material during cross-flow filtration.
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| 24. |
- Archambault, Alexi N., et al.
(författare)
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Cumulative Burden of Colorectal Cancer Associated Genetic Variants Is More Strongly Associated With Early-Onset vs Late-Onset Cancer
- 2020
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Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085 .- 1528-0012. ; 158:5, s. 1274-1286.e12
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Early-onset colorectal cancer (CRC, in persons younger than 50 years old) is increasing in incidence; yet, in the absence of a family history of CRC, this population lacks harmonized recommendations for prevention. We aimed to determine whether a polygenic risk score (PRS) developed from 95 CRC-associated common genetic risk variants was associated with risk for early-onset CRC.METHODS: We studied risk for CRC associated with a weighted PRS in 12,197 participants younger than 50 years old vs 95,865 participants 50 years or older. PRS was calculated based on single nucleotide polymorphisms associated with CRC in a large-scale genome-wide association study as of January 2019. Participants were pooled from 3 large consortia that provided clinical and genotyping data: the Colon Cancer Family Registry, the Colorectal Transdisciplinary Study, and the Genetics and Epidemiology of Colorectal Cancer Consortium and were all of genetically defined European descent. Findings were replicated in an independent cohort of 72,573 participants.RESULTS: Overall associations with CRC per standard deviation of PRS were significant for early-onset cancer, and were stronger compared with late-onset cancer (P for interaction = .01); when we compared the highest PRS quartile with the lowest, risk increased 3.7-fold for early-onset CRC (95% CI 3.28-4.24) vs 2.9-fold for late-onset CRC (95% CI 2.80-3.04). This association was strongest for participants without a first-degree family history of CRC (P for interaction = 5.61 x 10(-5)). When we compared the highest with the lowest quartiles in this group, risk increased 4.3-fold for early-onset CRC (95% CI 3.61-5.01) vs 2.9-fold for late-onset CRC (95% CI 2.70-3.00). Sensitivity analyses were consistent with these findings.CONCLUSIONS: In an analysis of associations with CRC per standard deviation of PRS, we found the cumulative burden of CRC-associated common genetic variants to associate with early-onset cancer, and to be more strongly associated with early-onset than late-onset cancer, particularly in the absence of CRC family history. Analyses of PRS, along with environmental and lifestyle risk factors, might identify younger individuals who would benefit from preventive measures.
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| 25. |
- Azar, Christian, 1969, et al.
(författare)
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The feasibility of low CO2 concentration targets and the role of bio-energy with carbon capture and storage (BECCS)
- 2010
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Ingår i: Climatic Change. - : Springer Science and Business Media LLC. - 1573-1480 .- 0165-0009. ; 100:1, s. 195-202
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Tidskriftsartikel (refereegranskat)abstract
- The United Nations Framework Convention on Climate Change (UNFCCC 1992) calls for stabilization of atmospheric greenhouse gas (GHG) concentrations at a level that would prevent dangerous anthropogenic interference with the climate system. We use three global energy system models to investigate the technological and economic attainability of meeting CO2 concentration targets below current levels. Our scenario studies reveal that while energy portfolios from a broad range of energy technologies are needed to attain low concentrations, negative emission technologies-e.g., biomass energy with carbon capture and storage (BECCS)-significantly enhances the possibility to meet low concentration targets (at around 350 ppm CO2).
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| 26. |
- Baker, Jessica H., et al.
(författare)
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Associations Between Alcohol Involvement and Drive for Thinness and Body Dissatisfaction in Adolescent Twins : A Bivariate Twin Study
- 2018
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Ingår i: Alcoholism. - : Wiley-Blackwell. - 0145-6008 .- 1530-0277. ; 42:11, s. 2214-2223
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Alcohol involvement has familial associations with bulimic symptoms (i.e., binge eating, inappropriate compensatory behaviors), with several studies indicating a genetic overlap between the two. It is unclear whether overlapping familial risk with alcohol involvement extends to other eating disorder symptoms. Understanding the genetic overlap between alcohol involvement and other eating disorder symptoms may aid in more targeted interventions for comorbid alcohol use-eating disorder symptoms. Thus, we investigated associations between alcohol involvement and 2 core eating disorder symptoms: drive for thinness and body dissatisfaction in adolescent female and male twins.METHODS: We assessed 3 levels of alcohol involvement: alcohol use in the last month, having ever been intoxicated, and alcohol intoxication frequency via self-report. The Eating Disorder Inventory-II assessed drive for thinness and body dissatisfaction. Sex-specific biometrical twin modeling examined the genetic overlap between alcohol involvement and eating disorder symptoms.RESULTS: Phenotypic associations between alcohol involvement, drive for thinness, and body dissatisfaction were significantly greater in girls compared with boys. A majority of the associations between alcohol involvement, drive for thinness, and body dissatisfaction in girls, but not boys, met our threshold for twin modeling (phenotypic r > 0.20). Moderate genetic correlations were observed between the 3 aspects of alcohol involvement and drive for thinness. Moderate genetic correlations were observed between alcohol use and intoxication frequency and body dissatisfaction.CONCLUSIONS: Together with the literature on alcohol involvement and bulimic symptoms, these findings suggest a generalized association between alcohol involvement and eating disorder symptoms in girls, whereas this association may be symptom specific in boys. Genetic correlations indicate that the amount and direction of this genetic overlap differs across specific symptoms. When intervening on comorbid alcohol involvement and eating disorder symptoms, it may be important to target-specific eating disorder symptoms.
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| 27. |
- Baker, Jessica H., et al.
(författare)
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Illicit Drug Use, Cigarette Smoking, and Eating Disorder Symptoms : Associations in an Adolescent Twin Sample
- 2018
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Ingår i: Journal of Studies on Alcohol and Drugs. - : Alcohol Research Documentation. - 1937-1888 .- 1938-4114. ; 79:5, s. 720-724
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Twin studies have shown that genetic factors in part explain the established relation between alcohol use (i.e., problematic use or abuse/dependence) and eating disorder symptoms in adolescent and adult females. However, studies have yet to elucidate if there are similar shared genetic factors between other aspects of substance involvement, such as illicit drug use and repeated cigarette smoking.Method: For those sex-specific phenotypic correlations above our threshold of.20, we used a behavioral genetic design to examine potential shared genetic overlap between self-reported lifetime illicit drug use and repeated cigarette smoking and the eating disorder symptoms of drive for thinness (DT), bulimia (BU), and body dissatisfaction (BD), as assessed with the Eating Disorder Inventory-II in 16- to 17-year-old female and male twin pairs.Results: Only phenotypic correlations with illicit drug use met our threshold for twin modeling. Small to moderate genetic correlations were observed between illicit drug use and BU in both girls and boys and between illicit drug use and in girls.Conclusions: Similar etiological factors are at play in the overlap between illicit drug use and certain eating disorder symptoms in girls and boys during adolescence, such that genetic factors are important for covariance. Specifically, illicit drug use was associated with bulimia nervosa symptoms in girls and boys, which parallels previous substance use research finding a genetic overlap between alcohol use and bulimia nervosa symptoms. Future research should prospectively examine developmental trajectories to further understand the etiological overlap between substance involvement and eating disorder symptoms.
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| 28. |
- Baker, Jessica H., et al.
(författare)
-
Shared Familial Risk Between Bulimic Symptoms and Alcohol Involvement During Adolescence
- 2017
-
Ingår i: Journal of Abnormal Psychology. - : American Psychological Association. - 0021-843X .- 1939-1846. ; 126:5, s. 506-518
-
Tidskriftsartikel (refereegranskat)abstract
- Twin studies show the established relation between bulimic symptoms and problematic alcohol involvement in adult females is partly due to shared familial factors, specifically shared genetic effects. However, it is unclear if similar shared etiological factors exist during adolescence or in males. We examined the familial overlap (i.e., genetic and common environmental correlations) between bulimic symptoms and various levels of alcohol involvement in 16- to 17-year-old female and male same-sex twin pairs using sex-specific biometrical twin modeling. Bulimic symptoms were assessed with the Eating Disorder Inventory-2. Alcohol involvement included alcohol use in the last month, having ever been intoxicated, and alcohol intoxication frequency. Results revealed 3 distinct patterns. First, in general, phenotypic correlations indicated statistically similar associations between bulimic symptoms and alcohol involvement in girls and boys. Second, common environmental overlap was significant for the bivariate associations including having ever been intoxicated. Third, moderate genetic correlations were observed between all bulimic symptoms and alcohol involvement in girls and moderate common environmental correlations were observed in boys for the more risky/deviant levels of involvement. Similar to adults, there is familial overlap between bulimic symptoms and alcohol involvement in adolescent girls and boys. These results could inform symptom-and sex-specific, developmentally targeted prevention and intervention programs for the comorbidity between bulimic symptoms and alcohol involvement.
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| 29. |
- Barrefelt, Asa, et al.
(författare)
-
Fluorescence labeled microbubbles for multimodal imaging
- 2015
-
Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 464:3, s. 737-742
-
Tidskriftsartikel (refereegranskat)abstract
- Air-filled polyvinyl alcohol microbubbles (PVA-MBs) were recently introduced as a contrast agent for ultrasound imaging. In the present study, we explore the possibility of extending their application in multimodal imaging by labeling them with a near infrared (NIR) fluorophore, VivoTag-680. PVA-MBs were injected intravenously into FVB/N female mice and their dynamic biodistribution over 24 h was determined by 3D-fluorescence imaging co-registered with 3D-mu CT imaging, to verify the anatomic location. To further confirm the biodistribution results from in vivo imaging, organs were removed and examined histologically using bright field and fluorescence microscopy. Fluorescence imaging detected PVA-MB accumulation in the lungs within the first 30 min post-injection. Redistribution to a low extent was observed in liver and kidneys at 4 h, and to a high extent mainly in the liver and spleen at 24 h. Histology confirmed PVA-MB localization in lung capillaries and macrophages. In the liver, they were associated with Kupffer cells; in the spleen, they were located mostly within the marginal-zone. Occasional MBs were observed in the kidney glomeruli and interstitium. The potential application of PVA-MBs as a contrast agent was also studied using ultrasound (US) imaging in subcutaneous and orthotopic pancreatic cancer mouse models, to visualize blood flow within the tumor mass. In conclusion, this study showed that PVA-MBs are useful as a contrast agent for multimodal imaging. (C) 2015 Elsevier Inc. All rights reserved.
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| 30. |
- Brikell, Isabell, et al.
(författare)
-
ADHD medication discontinuation and persistence across the lifespan : a retrospective observational study using population-based databases
- 2024
-
Ingår i: Lancet psychiatry. - : Elsevier. - 2215-0374 .- 2215-0366. ; 11:1, s. 16-26
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Although often intended for long-term treatment, discontinuation of medication for ADHD is common. However, cross-national estimates of discontinuation are missing due to the absence of standardised measures. The aim of this study was to determine the rate of ADHD treatment discontinuation across the lifespan and to describe similarities and differences across countries to guide clinical practice.METHODS: We did a retrospective, observational study using population-based databases from eight countries and one Special Administrative Region (Australia, Denmark, Hong Kong, Iceland, the Netherlands, Norway, Sweden, the UK, and the USA). We used a common analytical protocol approach and extracted prescription data to identify new users of ADHD medication. Eligible individuals were aged 3 years or older who had initiated ADHD medication between 2010 and 2020. We estimated treatment discontinuation and persistence in the 5 years after treatment initiation, stratified by age at initiation (children [age 4-11 years], adolescents [age 12-17 years], young adults [age 18-24 years], and adults [age ≥25 years]) and sex. Ethnicity data were not available.FINDINGS: 1 229 972 individuals (735 503 [60%] males, 494 469 females [40%]; median age 8-21 years) were included in the study. Across countries, treatment discontinuation 1-5 years after initiation was lowest in children, and highest in young adults and adolescents. Within 1 year of initiation, 65% (95% CI 60-70) of children, 47% (43-51) of adolescents, 39% (36-42) of young adults, and 48% (44-52) of adults remained on treatment. The proportion of patients discontinuing was highest between age 18 and 19 years. Treatment persistence for up to 5 years was higher across countries when accounting for reinitiation of medication; at 5 years of follow-up, 50-60% of children and 30-40% of adolescents and adults were covered by treatment in most countries. Patterns were similar across sex.INTERPRETATION: Early medication discontinuation is prevalent in ADHD treatment, particularly among young adults. Although reinitiation of medication is common, treatment persistence in adolescents and young adults is lower than expected based on previous estimates of ADHD symptom persistence in these age groups. This study highlights the scope of medication treatment discontinuation and persistence in ADHD across the lifespan and provides new knowledge about long-term ADHD medication use.FUNDING: European Union Horizon 2020 Research and Innovation Programme.
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| 31. |
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| 32. |
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| 33. |
- Brouzoulis, Jim, 1984, et al.
(författare)
-
Strategies for planar crack propagation based on the concept of material forces
- 2011
-
Ingår i: Computational Mechanics. - : Springer Science and Business Media LLC. - 1432-0924 .- 0178-7675. ; 47:3, s. 295-304
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a computational framework for the simulation of planar crack growth (including kinking) driven by "material forces". An evolution law for the crack tip position is formulated, which is shown to give rise to different propagation strategies when subjected to certain assumptions on regularity. Three such strategies, that previously have been proposed in the literature in principle: Explicit Proportional Extension (EPE), Implicit Proportional Extension (IPE) and Maximum Parallel Release Rate (MPRR), are outlined and assessed. Based on the results of two numerical examples, it is concluded that the presented propagation strategies produce almost identical results and are robust with respect to time discretization.
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| 34. |
- Börjesson, Elias, 1992, et al.
(författare)
-
Variationally consistent homogenisation of plates
- 2023
-
Ingår i: Computer Methods in Applied Mechanics and Engineering. - 0045-7825. ; 413
-
Tidskriftsartikel (refereegranskat)abstract
- Advanced fibre composite materials are often used for weight-efficient thin-walled designs, making a plate-based modelling approach suitable for their structural assessment. However, as the sub-structural geometrical features of these materials govern much of their behaviour, a multi-scale approach is necessary. A related challenge, however, is that the in-plane variation of these sub-structural features may be much larger than the total thickness of the material, whereby tailored homogenisation techniques for shell elements are needed. Existing frameworks for plate- and shell-based homogenisation are typically developed using second-order homogenisation in combination with the Hill–Mandel (macro-homogeneity) condition. However, it has been reported in the literature that this approach can lead to kinematic inconsistencies in the macro- to micro-scale transition. One inconsistency that is commonly reported, is the inability to correctly account for the macro-scale transverse shear behaviour on the sub-scale level. In this contribution, we show how the method of Variationally Consistent Homogenisation (VCH) can be used to develop a homogenisation framework for Reissner-Mindlin plate elements, which guarantees kinematically consistent prolongation and homogenisation operations. The homogenisation approach is demonstrated in four numerical examples, where it is shown that the method accurately homogenise the effective sectional plate stiffnesses of homogeneous and heterogeneous sub-structures.
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| 35. |
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| 36. |
- Carling, Kenneth, et al.
(författare)
-
Does early intervention help the unemployed youth?
- 2005
-
Ingår i: Labour Economics. - 0927-5371 .- 1879-1034. ; 12:3, s. 301-319
-
Tidskriftsartikel (refereegranskat)abstract
- This paper evaluates a measure targeted at unemployed individuals aged 20–24. The main purpose of the measure is to prevent long-term unemployment by guaranteeing an assignment to some labor market program within 100 days of unemployment. Municipalities voluntarily agree to offer the guarantee. To identify the effect of the measure, we use three conditions: The guarantee covers individuals aged 24 but not 25, one fifth of the municipalities does not provide the guarantee, and the guarantee existed in 1998 but not in 1997. We find no evidence that the measure did significantly improve the future labor market situation of the youth, which suggests that early intervention in the unemployment spell is not important.
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| 37. |
- Carlsson, Kristoffer, 1989, et al.
(författare)
-
A Comparison of Computational Formats of Gradient-Extended Crystal Viscoplasticity in the Context of Selective Homogenization
- 2016
-
Ingår i: Eccomas, 5-10 juni, Kreta, 2016 (1 page abstract).
-
Konferensbidrag (refereegranskat)abstract
- Crystal (visco)plasticity is the accepted model framework for incorporating microstructural information incontinuum theory with application to crystalline metals, where dislocations constitute the physicalmechanism behind inelastic deformation. In order to account for the size effects due to the existence ofgrain boundaries in a polycrystal, it is convenient to include some sort of gradient-extension of the flowproperties along the slip directions, either in the dragstress or backstress (from GND’s). Various explicitmodels based on this conceptual background have been proposed, e.g. Gurtin et al.[1], Gottschalk et al.[2];however, several modeling issues still await its resolution. A comprehensive unifying account of gradienttheory for a variety of application models was presented by Miehe[3]. When applied to a polycrystal, it isdesirable that the homogenization strategy will result in a standard continuum format on the macroscale,whereas micro-stresses are confined to the mesoscale and and automatically "suppressed" during theprocedure of (selective) homogenization. This can be achieved within a fairly general setting of variationallyconsistent homogenization. In this contribution we focus on issues related to the computational format ofgradient-extended crystal viscoplasticity that constitutes the RVE-problem. A few different variationalformats are thereby investigated. The so-called “primal” format exploits the slip on each slip system togetherwith the displacement field as the unknown global fields. An alternative format is coined the “semi-dualformat”, in which the slip variables are replaced by the microstresses as global fields, thereby defining amixed variational problem. For both the primal and semi-dual formulations, we establish variationalprinciples for the time incremental FE-problems which ensure symmetry of the corresponding tangentproblems. We note that a mixed method that bears strong resemblance with the semi-dual format has beenused extensively in our research group in recent years, e.g. Bargmann et al.[4]; however, without possessing awell-defined variational structure. We compare the primal and semi-dual variational formats in terms of prosand cons from various aspects. We also discuss the pertinent FE-spaces that appear as the natural/possiblechoices and assess the computational efficiency of the FE-approximations with the aid of numericalexamples pertaining to a single crystal as well as to a polycrystal in the homogenization context.References:[1] M. E. Gurtin, L. Anand, S. P. Lele, Journal of the Mechanics and Physics of Solids, 55, 1853, (2007)[2] D. Gottschalk, A. McBride, B.D. Reddy, A. Javili, P. Wriggers, C.B. Hirschberger, ComputationalMaterial Science, 111, 443, (2016)[3] C. Miehe, J. Mech. Phys. Solids, 59 898, (2011)[4] S. Bargmann, M. Ekh, K. Runesson, B. Svendsen, Philosophical Magazine, 90, 1263, (2010)
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| 38. |
- Carlsson, Kristoffer, 1989, et al.
(författare)
-
A comparison of the primal and semi-dual variational formats of gradient-extended crystal inelasticity
- 2017
-
Ingår i: Computational Mechanics. - : Springer Science and Business Media LLC. - 1432-0924 .- 0178-7675. ; 60:4, s. 531-548
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper we discuss issues related to the theoretical as well as the computational format of gradient-extended crystal viscoplasticity. The so-called primal format uses the displacements, the slip of each slip system and the dissipative stresses as the primary unknown fields. An alternative format is coined the semi-dual format, which in addition includes energetic microstresses among the primary unknown fields. We compare the primal and semi-dual variational formats in terms of advantages and disadvantages from modeling as well as numerical viewpoints. Finally, we perform a series of representative numerical tests to investigate the rate of convergence with finite element mesh refinement. In particular, it is shown that the commonly adopted microhard boundary condition poses a challenge in the special case that the slip direction is parallel to a grain boundary.
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| 39. |
- Carlsson, Kristoffer, 1989, et al.
(författare)
-
Bounds on the effective response for gradient crystal inelasticity based on homogenization and virtual testing
- 2019
-
Ingår i: International Journal for Numerical Methods in Engineering. - : Wiley. - 0029-5981 .- 1097-0207. ; 119:4, s. 281-304
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the application of variationally consistent selective homogenization applied to a polycrystal with a subscale model of gradient-enhanced crystal inelasticity. Although the full gradient problem is solved on Statistical Volume Elements (SVEs), the resulting macroscale problem has the formal character of a standard local continuum. A semi-dual format of gradient inelasticity is exploited, whereby the unknown global variables are the displacements and the energetic micro-stresses on each slip-system. The corresponding time-discrete variational formulation of the SVE-problem defines a saddle point of an associated incremental potential. Focus is placed on the computation of statistical bounds on the effective energy, based on virtual testing on SVEs and an argument of ergodicity. As it turns out, suitable combinations of Dirichlet and Neumann conditions pertinent to the standard equilibrium and the micro-force balance, respectively, will have to be imposed. Whereas arguments leading to the upper bound are quite straightforward, those leading to the lower bound are significantly more involved; hence, a viable approximation of the lower bound is computed in this paper. Numerical evaluations of the effective strain energy confirm the theoretical predictions. Furthermore, heuristic arguments for the resulting macroscale stress-strain relations are numerically confirmed.
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| 40. |
- Carlsson, Kristoffer, 1989, et al.
(författare)
-
COMPUTATIONAL ISSUES OF GRADIENT-EXTENDED CRYSTAL INELASTICITY
- 2016
-
Ingår i: NSCM, 26 - 28 October, Göteborg, 2016 4 page extended abstract.
-
Konferensbidrag (refereegranskat)abstract
- . In this paper we discuss issues related to the theoretical as well as the computationalformat of gradient-extended crystal viscoplasticity. The so-called “primal”format uses the internal variables and the displacements as the primary unknown fields.An alternative format is coined the “semi-dual format”, which in addition includes microstresses,thereby defining a mixed variational problem. We compare the primal andsemi-dual variational formats in terms of pros and cons from a modeling as well as anumerical viewpoint. We perform a set of numerical benchmarks to investigate the rateof convergence for errors in different norms.
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| 41. |
- Carlsson, Kristoffer, 1989, et al.
(författare)
-
Computational modeling issues of gradient-extended viscoplasticity
- 2015
-
Ingår i: Svenska Mekanikdagar, 10-12 juni, Linköping, 2015 (1 page abstract).
-
Konferensbidrag (refereegranskat)abstract
- Crystal (visco)plasticity is the accepted model framework for incorporating microstructural in-formation in continuum theory with application to crystalline metals where dislocations constitute thephysical mechanism behind inelastic deformation. In order to account for the size effects due to the ex-istence of grain boundaries in a polycrystal, it is convenient to include some sort of gradient-extensionof the flow properties along the slip directions, either in the dragstress or backstress (from GND, whichare generally of two types: edge and screw dislocations). Various explicit models based on this con-ceptual background have been proposed, not the least by Gurtin and coworkers 1 ; however, severalmodeling issues still await its resolution. An elegant way of unifying gradient theory for differentapplication models was presented by Miehe 2 .In this contribution we focus on issues related to the theoretical as well as the computationalformat, while (for the sake of clarity) restricting to gradient-extended viscoplasticity for a standardcontinuum. Thereby, we avoid the additional complications associated with the proper version ofcrystal (visco) plasticity, such as higher order boundary conditions. The so-called “primal” formatexploits the internal variables as the primary unknown field together with the displacement field. Analternative format is coined the “semi-dual format”, which exploits (in addition) the microstresses,thereby defining a mixed variational problem. We note that a mixed method that bears resemblancewith the semi-dual format has been used extensively in our research group in recent years 3 ; however,without possessing a well-defined variational structure.We compare the primal and semi dual variational formats in terms of pros and cons from variousaspects. We also discuss the pertinent FE-spaces that appear as the natural/possible choices. In partic-ular, for the semi-dual format we investigate the possibility to use a minimal degree of regularity thathas so far not been discussed in the literature.
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| 42. |
- Carlsson, Kristoffer, 1989, et al.
(författare)
-
ON THE PRIMAL AND MIXED DUAL FORMATS IN VARIATIONALLY CONSISTENT COMPUTATIONAL HOMOGENIZATION WITH EMPHASIS ON FLUX BOUNDARY CONDITIONS
- 2020
-
Ingår i: International Journal for Multiscale Computational Engineering. - 1543-1649. ; 18:6, s. 651-675
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, we view homogenization within the framework of variational multiscale methods. The standard (primal) variational format lends itself naturally to the choice of Dirichlet boundary conditions on the Representative Volume Element (RVE). However, how to impose flux boundary conditions, treated as Neumann conditions in the standard variational format, is less obvious. Therefore, in this paper we propose and investigate a novel mixed variational setting, where the fluxes are treated as additional primary fields, in order to provide the natural variational environment for such flux boundary conditions. This mixed dual formulation allows for a conforming implementation of (lower bound) flux boundary conditions in the framework of discretization-based homogenization. To focus on essential features, a very simple problem is studied: the classical stationary linear heat equation. Furthermore, we consider the standard context of model-based homogenization (without loss of generality), since we are only concerned with the RVE problem and merely assume that the relevant macroscale fields are properly prolonged. Numerical results from the primary and the mixed dual variational formats are compared and their convergence properties for mesh finite element (FE) refinement and RVE size are assessed.
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| 43. |
- Carlstedt, David, 1984, et al.
(författare)
-
Computational modelling of structural batteries accounting for stress-assisted convection in the electrolyte
- 2022
-
Ingår i: International Journal of Solids and Structures. - : Elsevier BV. - 0020-7683. ; 238
-
Tidskriftsartikel (refereegranskat)abstract
- Structural batteries consist of carbon fibres embedded in a porous structural battery electrolyte (SBE), which is composed of two continuous phases: a solid polymer skeleton and a liquid electrolyte containing Li-salt. In this paper we elaborate on a computational modelling framework to study the electro-chemo-mechanical properties of such structural batteries while accounting for the combined action from migration as well as stress-assisted diffusion and convection in the electrolyte. Further, we consider effects of lithium insertion in the carbon fibres, leading to insertion strains. The focus is placed on how the convective contribution to the mass transport within the SBE affects the general electro-chemo-mechanical properties. The numerical results indicate that the convective contribution has only minor influence on the multifunctional performance when the mechanical loading is caused by constrained deformation of constituents during electro-chemical cycling. However, in the case of externally applied mechanical loading that causes severe deformation of the SBE, or when large current pulses are applied, the convective contribution has noticeable influence on the electro-chemical performance. In addition, it is shown that the porosity of the SBE, which affects the effective stiffness as well as the mobility and permeability, has significant influence on the combined mechanical and electro-chemical performance.
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| 44. |
- Carlstedt, David, 1984, et al.
(författare)
-
Electro-chemo-mechanically coupled computational modelling of structural batteries
- 2020
-
Ingår i: Multifunctional Materials. - : IOP Publishing. - 2399-7532. ; 3:4
-
Tidskriftsartikel (refereegranskat)abstract
- Structural batteries are multifunctional composites that combine load-bearing capacity with electro-chemical energy storage capability. The laminated architecture is considered in this paper, whereby restriction is made to a so called half-cell in order to focus on the main characteristics and provide a computational tool for future parameter studies. A thermodynamically consistent modelling approach is exploited for the relevant electro-chemo-mechanical system. We consider effects of lithium insertion in the carbon fibres, leading to insertion strains, while assuming transverse isotropy. Further, stress-assisted ionic transport is accounted for in addition to standard diffusion and migration. The relevant space-variational problems that result from time discretisation are established and evaluated in some detail. The proposed model framework is applied to a generic/idealized material representation to demonstrate its functionality and the importance of accounting for the electro-chemo-mechanical coupling effects. As a proof of concept, the numerical studies reveal that it is vital to account for two-way coupling in order to predict the multifunctional (i.e. combined electro-chemo-mechanical) performance of structural batteries.
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| 45. |
- Carlstedt, David, 1984, et al.
(författare)
-
Experimental and computational characterization of carbon fibre based structural battery electrode laminae
- 2022
-
Ingår i: Composites Science and Technology. - : Elsevier BV. - 0266-3538. ; 220
-
Tidskriftsartikel (refereegranskat)abstract
- In this paper, electrode laminae consisting of carbon fibres embedded in structural battery electrolyte (CF-SBE electrodes) are characterized with respect to their multifunctional (i.e. combined electrochemical and mechanical) performance utilizing experimental and numerical techniques. The studied material is made from commercially available polyacrylonitrile (PAN)-based carbon fibres and a porous SBE matrix/electrolyte, which is composed of two continuous phases: a solid polymer skeleton (vinyl ester-based) and a Li-salt containing liquid electrolyte. Experimental and numerical studies are performed on CF-SBE electrode half-cells, whereby a coupled electro-chemo-mechanical finite element model is exploited. Results show that, similar to traditional batteries, electrode thickness, transport properties of the electrolyte and applied current significantly affect electrochemical performance. For example, increasing the electrode thickness of the studied CF-SBE electrode from 50 μm to 200 μm results in a reduction in specific capacity of approximately 70/95% for an applied current of 30/120 mA g? 1 of fibres, respectively. Further, Li-insertion induced longitudinal expansion of carbon fibre electrodesare video microscopically recorded during charge/discharge conditions. In liquid electrolyte the total/reversible longitudinal expansion are found to be 0.85/0.8% while for the CF-SBE electrode the reversible expansion is found to be 0.6%. The fibre expansion in the CF-SBE electrode gives rise to residual strains which is demonstrated numerically. We expect that the utilized computational framework and experimental data open a route to develop high-performing, both mechanically and electrochemically, carbon fibre based battery electrode laminae for future lightweight structural components with energy storage ability.
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| 46. |
- Carlstedt, David, 1984, et al.
(författare)
-
On the coupled thermo–electro–chemo–mechanical performance of structural batteries with emphasis on thermal effects
- 2022
-
Ingår i: European Journal of Mechanics, A/Solids. - : Elsevier BV. - 0997-7538. ; 94
-
Tidskriftsartikel (refereegranskat)abstract
- Carbon fibre (CF) based structural batteries is a type of battery designed to sustain mechanical loads. In this paper, a fully coupled thermo–electro–chemo–mechanical computational modelling framework for CF based structural batteries is presented. We consider the combined effects of lithium insertion in the carbon fibres leading to insertion strains, and thermal expansion/shrinkage of the constituents leading to thermal (free) strains, while assuming transverse isotropy. The numerical studies show that the developed framework is able to capture the coupled thermo–electro–chemo–mechanical behaviour. Moreover, it is found that the dominating source for heat generation during galvanostatic cycling is associated with discontinuities in the electrical and chemical potentials at the fibre/electrolyte interface. Further, a limited parameter study shows that the temperature change during electrochemical cycling is significantly influenced by the applied current, thermal properties of the constituents and heat exchange with the surroundings. Finally, for large temperature variations, e.g. as identified during relevant (dis)charge conditions, the magnitude of the thermal strains in the structural battery electrolyte (SBE) are found to be similar to the insertion induced strains.
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| 47. |
- Carlstedt, David, 1984, et al.
(författare)
-
Unit cells for multiphysics modelling of structural battery composites
- 2019
-
Ingår i: ICCM International Conferences on Composite Materials.
-
Konferensbidrag (refereegranskat)abstract
- To predict the multifunctional performance of structural battery composites, multiple physical phenomena need to be studied simultaneously. Hence, multiphysics models are needed to evaluate the complete performance of this composite material. In this study the coupled analysis for multiphysics modelling of structural battery composites is presented and modelling strategies and unit cell designs are discussed with respect to the different physical models. Furthermore, FE-models are setup in the commercial Finite Element (FE) software COMSOL to study if existing physics-based modelling techniques and homogenization schemes for conventional lithium ion batteries can be used to describe the electrochemical behaviour of structural battery composites. To predict the microscopic behaviour, the local variation of the mass and charge concentrations need to be accounted for. Hence, refined models with appropriate boundary conditions are needed to capture the microscopic conditions inside the material. The numerical results demonstrate that conventional physics-based 1D battery models and homogenization schemes based on porous media theory can be used to predict the macroscopic electrical behaviour of the fibrous structural battery. For future work electrochemical experiments on battery cell level are planned to validate the numerical results.
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| 48. |
- Carlstedt, David, 1984, et al.
(författare)
-
Variationally consistent modeling of a sensor-actuator based on shape-morphing from electro-chemical–mechanical interactions
- 2023
-
Ingår i: Journal of the Mechanics and Physics of Solids. - 0022-5096. ; 179
-
Tidskriftsartikel (refereegranskat)abstract
- This paper concerns the computational modeling of a class of carbon fiber composites, known as shape-morphing and strain-sensing composites. The actuating and sensing performance of such (smart) materials is achieved by the interplay between electrochemistry and mechanics, in particular the ability of carbon fibers to (de)intercalate Li-ions repeatedly. We focus on the actuation and sensing properties of a beam in conjunction with the appropriate “through-the-thickness” properties. Thus, the electro-chemo-mechanical analysis is essentially two-dimensional, and it is possible to rely heavily on the results in Carlstedt et al. (2020). More specifically, the cross-sectional design is composed of two electrodes, consisting of (partly) lithiated carbon fibers embedded in structural battery electrolyte (SBE), on either side of a separator. As a result, the modeling is hierarchical in the sense that (macroscale) beam action is combined with electro-chemo-mechanical interaction along the beam. The setup is able to work as sensor or actuator depending on the choice of control (and response) variables. Although quite idealized, this design allows for a qualitative investigation. In this paper we demonstrate the capability of the developed framework to simulate both the actuator and sensor modes. As proof of concept, we show that both modes of functionality can be captured using the developed framework. For the actuator mode, the predicted deformation is found to be in close agreement with experimental data. Further, the sensor-mode is found to agree with experimental data available in the literature.
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| 49. |
- Chen, Zhishan, et al.
(författare)
-
Fine-mapping analysis including over 254 000 East Asian and European descendants identifies 136 putative colorectal cancer susceptibility genes
- 2024
-
Ingår i: Nature Communications. - : Springer Nature. - 2041-1723. ; 15:1
-
Tidskriftsartikel (refereegranskat)abstract
- Genome-wide association studies (GWAS) have identified more than 200 common genetic variants independently associated with colorectal cancer (CRC) risk, but the causal variants and target genes are mostly unknown. We sought to fine-map all known CRC risk loci using GWAS data from 100,204 cases and 154,587 controls of East Asian and European ancestry. Our stepwise conditional analyses revealed 238 independent association signals of CRC risk, each with a set of credible causal variants (CCVs), of which 28 signals had a single CCV. Our cis-eQTL/mQTL and colocalization analyses using colorectal tissue-specific transcriptome and methylome data separately from 1299 and 321 individuals, along with functional genomic investigation, uncovered 136 putative CRC susceptibility genes, including 56 genes not previously reported. Analyses of single-cell RNA-seq data from colorectal tissues revealed 17 putative CRC susceptibility genes with distinct expression patterns in specific cell types. Analyses of whole exome sequencing data provided additional support for several target genes identified in this study as CRC susceptibility genes. Enrichment analyses of the 136 genes uncover pathways not previously linked to CRC risk. Our study substantially expanded association signals for CRC and provided additional insight into the biological mechanisms underlying CRC development.
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| 50. |
- Dahl, Kenneth, et al.
(författare)
-
Good manufacturing procedure production of [18 F]SynVesT-1, a radioligand for in vivo positron emission tomography imaging of synaptic vesicle glycoprotein 2A.
- 2022
-
Ingår i: Journal of labelled compounds & radiopharmaceuticals. - : Wiley. - 1099-1344 .- 0362-4803. ; 65:12, s. 315-322
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Tidskriftsartikel (refereegranskat)abstract
- [18 F]SynVesT-1 (also known as [18 F]SDM-8 or [18 F]MNI-1126) is a potent and selective synaptic vesicle glycoprotein 2 (SV2A) positron emission tomography (PET) imaging agent. In order to fulfill the increasing clinical demand of an 18 F-labeled SV2A PET ligand, we have developed a fully automated procedure to provide a sterile and pyrogen-free good manufacturing procedure (GMP)-compliant product of [18 F]SynVesT-1 suitable for clinical studies in humans. [18 F]SynVesT-1 is synthesized via a rapid copper-mediated radiofluorination protocol. The procedure was developed and established on a commercially available module, TracerMaker (ScanSys Laboratorieteknik ApS, Copenhagen, Denmark), a synthesis platform originally developed to conduct carbon-11 radiochemistry. From ~130GBq (end-of-bombardment), our newly developed procedure enabled us to prepare [18 F]SynVesT-1 in an isolated radioactivity yield of 14,220±800MBq (n=3), which corresponds to a radiochemical yield (RCY) of 19.5±0.5%. The radiochemical purity (RCP) and enantiomeric purity of each of the final formulated batches exceeded 98%. The overall synthesis time was 90min and the molar activity was 330±60GBq/μmol (8.9±1.6Ci/μmol). The produced [18 F]SynVesT-1 was stable over 8h at room temperature and is suitable for in vivo PET imaging studies in human subjects.
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