| 1. |
- Ahlsson, Anders, 1962-, et al.
(författare)
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A Swedish consensus on the surgical treatment of concomitant atrial fibrillation
- 2012
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Ingår i: Scandinavian Cardiovascular Journal. - London, United Kingdom : Informa Healthcare. - 1401-7431 .- 1651-2006. ; 46:4, s. 212-218
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Forskningsöversikt (refereegranskat)abstract
- Atrial fibrillation (AF) is a common arrhythmia among patients scheduled for open heart surgery and is associated with increased morbidity and mortality. According to international guidelines, symptomatic and selected asymptomatic patients should be offered concomitant surgical AF ablation in conjunction with valvular or coronary surgery. The gold standard in AF surgery is the Cox Maze III ("cut-and-sew") procedure, with surgical incisions in both atria according to a specified pattern, in order to prevent AF reentry circuits from developing. Over 90% of patients treated with the Cox Maze III procedure are free of AF after 1 year. Recent developments in ablation technology have introduced several energy sources capable of creating nonconducting atrial wall lesions. In addition, simplified lesion patterns have been suggested, but results with these techniques have been unsatisfactory. There is a clear need for standardization in AF surgery. The Swedish Arrhythmia Surgery Group, represented by surgeons from all Swedish units for cardiothoracic surgery, has therefore reached a consensus on surgical treatment of concomitant AF. This consensus emphasizes adherence to the lesion pattern in the Cox Maze III procedure and the use of biatrial lesions in nonparoxysmal AF.
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| 2. |
- Ragnarsson, Sigurdur, et al.
(författare)
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No-touch saphenous vein grafts in coronary artery surgery (SWEDEGRAFT): Rationale and design of a multicenter, prospective, registry-based randomized clinical trial
- 2020
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Ingår i: American Heart Journal. - : MOSBY-ELSEVIER. - 0002-8703 .- 1097-6744. ; 224, s. 17-24
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Tidskriftsartikel (refereegranskat)abstract
- The SWEDEGRAFT study (ClinicalTrials.gov Identifier: NCT03501303) tests the hypothesis that saphenous vein grafts (SVGs) harvested with the "no-touch" technique improves patency of coronary artery bypass grafts compared with the conventional open skeletonized technique. This article describes the rationale and design of the randomized trial and baseline characteristics of the population enrolled during the first 9 months of enrollment. The SWEDEGRAFT study is a prospective, binational multicenter, open-label, registry-based trial in patients undergoing first isolated nonemergent coronary artery bypass grafting (CABG), randomized 1:1 to no-touch or conventional open skeletonized vein harvesting technique, with a planned enrollment of 900 patients. The primary end point is the proportion of patients with graft failure defined as SVGs occluded or stenosed >50% on coronary computed tomography angiography at 2 years after CABG, earlier clinically driven coronary angiography demonstrating an occluded or stenosed >50% vein graft, or death within 2 years. High-quality health registries and coronary computed tomography angiography are used to assess the primary end point. The secondary end points include wound healing in the vein graft sites and the composite outcome of major adverse cardiac events during the first 2 years based on registry data. Demographics of the first 200 patients enrolled in the trial and other CABG patients operated in Sweden during the same time period are comparable when the exclusion criteria are taken into consideration.
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| 3. |
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| 4. |
- Dunås, Tora, et al.
(författare)
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Accuracy of blood flow assessment in cerebral arteries with 4D flow MRI : Evaluation with three segmentation methods
- 2019
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1053-1807 .- 1522-2586. ; 50:2, s. 511-518
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Tidskriftsartikel (refereegranskat)abstract
- Background: Accelerated 4D flow MRI allows for high‐resolution velocity measurements with whole‐brain coverage. Such scans are increasingly used to calculate flow rates of individual arteries in the vascular tree, but detailed information about the accuracy and precision in relation to different postprocessing options is lacking.Purpose: To evaluate and optimize three proposed segmentation methods and determine the accuracy of in vivo 4D flow MRI blood flow rate assessments in major cerebral arteries, with high‐resolution 2D PCMRI as a reference.Study Type: Prospective.Subjects: Thirty‐five subjects (20 women, 79 ± 5 years, range 70–91 years).Field Strength/Sequence: 4D flow MRI with PC‐VIPR and 2D PCMRI acquired with a 3 T scanner.Assessment: We compared blood flow rates measured with 4D flow MRI, to the reference, in nine main cerebral arteries. Lumen segmentation in the 4D flow MRI was performed with k‐means clustering using four different input datasets, and with two types of thresholding methods. The threshold was defined as a percentage of the maximum intensity value in the complex difference image. Local and global thresholding approaches were used, with evaluated thresholds from 6–26%.Statistical Tests: Paired t‐test, F‐test, linear correlation (P < 0.05 was considered significant) along with intraclass correlation (ICC).Results: With the thresholding methods, the lowest average flow difference was obtained for 20% local (0.02 ± 15.0 ml/min, ICC = 0.97, n = 310) or 10% global (0.08 ± 17.3 ml/min, ICC = 0.97, n = 310) thresholding with a significant lower standard deviation for local (F‐test, P = 0.01). For all clustering methods, we found a large systematic underestimation of flow compared with 2D PCMRI (16.1–22.3 ml/min).Data Conclusion: A locally adapted threshold value gives a more stable result compared with a globally fixed threshold. 4D flow with the proposed segmentation method has the potential to become a useful reliable clinical tool for assessment of blood flow in the major cerebral arteries.Level of Evidence: 2Technical Efficacy: Stage 2
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| 5. |
- Hansson, Emma C., 1985, et al.
(författare)
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Coronary artery bypass grafting-related bleeding complications in patients treated with ticagrelor or clopidogrel : a nationwide study
- 2016
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 37:2, s. 189-197
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Tidskriftsartikel (refereegranskat)abstract
- AIMS:Excessive bleeding impairs outcome after coronary artery bypass grafting (CABG). Current guidelines recommend withdrawal of clopidogrel and ticagrelor 5 days (120 h) before elective surgery. Shorter discontinuation would reduce the risk of thrombotic events and save hospital resources, but may increase the risk of bleeding. We investigated whether a shorter discontinuation time before surgery increased the incidence of CABG-related major bleeding complications and compared ticagrelor- and clopidogrel-treated patients.METHODS AND RESULTS:All acute coronary syndrome patients in Sweden on dual antiplatelet therapy with aspirin and ticagrelor (n = 1266) or clopidogrel (n = 978) who underwent CABG during 2012-13 were included in a retrospective observational study. The incidence of major bleeding complications according to the Bleeding Academic Research Consortium-CABG definition was 38 and 31%, respectively, when ticagrelor/clopidogrel was discontinued <24 h before surgery. Within the ticagrelor group, there was no significant difference between discontinuation 72-120 or >120 h before surgery [odds ratio (OR) 0.93 (95% confidence interval, CI, 0.53-1.64), P = 0.80]. In contrast, clopidogrel-treated patients had a higher incidence when discontinued 72-120 vs. >120 h before surgery (OR 1.71 (95% CI 1.04-2.79), P = 0.033). The overall incidence of major bleeding complications was lower with ticagrelor [12.9 vs. 17.6%, adjusted OR 0.72 (95% CI 0.56-0.92), P = 0.012].CONCLUSION:The incidence of CABG-related major bleeding was high when ticagrelor/clopidogrel was discontinued <24 h before surgery. Discontinuation 3 days before surgery, as opposed to 5 days, did not increase the incidence of major bleeding complications with ticagrelor, but increased the risk with clopidogrel. The overall risk of major CABG-related bleeding complications was lower with ticagrelor than with clopidogrel.
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| 6. |
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| 7. |
- Holmgren, Gustav, 1983-, et al.
(författare)
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Identification of novel biomarkers for doxorubicin-induced toxicity in human cardiomyocytes derived from pluripotent stem cells
- 2015
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Ingår i: Toxicology. - : Elsevier. - 0300-483X .- 1879-3185. ; 328, s. 102-111
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Tidskriftsartikel (refereegranskat)abstract
- Doxorubicin is a chemotherapeutic agent indicated for the treatment of a variety of cancer types, including leukaemia, lymphomas, and many solid tumours. The use of doxorubicin is, however, associated with severe cardiotoxicity, often resulting in early discontinuation of the treatment. Importantly, the toxic symptoms can occur several years after the termination of the doxorubicin administration. In this study, the toxic effects of doxorubicin exposure have been investigated in cardiomyocytes derived from human embryonic stem cells (hESC). The cells were exposed to different concentrations of doxorubicin for up to 2 days, followed by a 12 day recovery period. Notably, the cell morphology was altered during drug treatment and the cells showed a reduced contractile ability, most prominent at the highest concentration of doxorubicin at the later time points. A general cytotoxic response measured as Lactate dehydrogenase leakage was observed after 2 days' exposure compared to the vehicle control, but this response was absent during the recovery period. A similar dose-dependant pattern was observed for the release of cardiac specific troponin T (cTnT) after 1 day and 2 days of treatment with doxorubicin. Global transcriptional profiles in the cells revealed clusters of genes that were differentially expressed during doxorubicin exposure, a pattern that in some cases was sustained even throughout the recovery period, suggesting that these genes could be used as sensitive biomarkers for doxorubicin-induced toxicity in human cardiomyocytes. The results from this study show that cTnT release can be used as a measurement of acute cardiotoxicity due to doxorubicin. However, for the late onset of doxorubicin-induced cardiomyopathy, cTnT release might not be the most optimal biomarker. As an alternative, some of the genes that we identified as differentially expressed after doxorubicin exposure could serve as more relevant biomarkers, and may also help to explain the cellular mechanisms behind the late onset apoptosis associated with doxorubicin-induced cardiomyopathy.
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| 8. |
- Holmgren, Madelene, 1992-
(författare)
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4D flow MRI and modelling to assess cerebral arterial hemodynamics : method development and evaluation, with implementation in patients with symptomatic carotid stenosis
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Blood flow measurements are important for understanding the development of cerebrovascular diseases. With 4D flow magnetic resonance imaging (4D flow MRI), simultaneous velocity measurements are obtained in all cerebral arteries in a scan of about ten minutes. However, 4D flow MRI is a relatively new technique. For usefulness in both clinics and research, detailed knowledge is needed about its accuracy and precision for flow quantification. In patients with stroke or transient ischemic attack (TIA) from a symptomatic carotid stenosis, the stenosis may generate a difference in blood pressure and flow between the left and right cerebral hemispheres. Such a hemispheric pressure difference could be an early marker of to what extent a stenosis is affecting cerebral hemodynamics, which could be useful in the planning of carotid surgery. The overall aim of the thesis was to determine the accuracy of 4D flow MRI to measure cerebral arterial blood flow, and to develop and evaluate an approach combining 4D flow MRI and computational fluid dynamics (CFD) to characterize the cerebral arterial hemodynamics, with implementation in patients with symptomatic carotid stenosis. The thesis is based on four papers, investigating two cohorts.The first cohort consisted of 35 elderly volunteers (mean age 79 years) and was studied in paper I-II. Blood flow rates were measured in nine cerebral arteries with 4D flow MRI and 2D phase-contrast MRI as reference. Three different flow quantification methods for 4D flow MRI were evaluated and optimized: one clustering approach and two threshold-based methods. The proposed new method, based on a locally adapted threshold, outperformed the previously suggested methods in flow rate quantification. For the clustering method, flow rates were systematically underestimated. 4D flow MRI was also evaluated to assess different arterial pulsatility measures, and a Windkessel model was used to estimate reference values for cerebrovascular resistance and cerebral arterial compliance in elderly.The second cohort consisted of 28 stroke and TIA patients (mean age 73 years) with symptomatic carotid stenosis and was studied in paper III-IV. With 4D flow MRI and CFD, the preoperative hemispheric pressure laterality was quantified in the patients. The pressure laterality was compared to hemispheric flow lateralities. Estimating the hemispheric pressure laterality was a promising physiological biomarker for grading the cerebral arterial hemodynamic disturbances in patients with symptomatic carotid stenosis. A CFD model was also developed to predict carotid stump pressure, i.e., the important pressure measured in the clamped carotid artery during surgical removal of the stenosis. The predicted stump pressures were correlated with the pressures measured during surgery. Stump pressure prediction was promising and could be a potential tool in the preoperative planning in order to avoid hypoperfusion during surgery. In summary, post-processing methods were successfully developed and evaluated for accurate assessment of mean and pulsatile cerebral blood flow rates with 4D flow MRI. Thereby, this thesis provided knowledge about possibilities and limitations of how 4D flow MRI can be used with respect to cerebral arterial blood flow rate assessment. By contributing with models combining 4D flow MRI and CFD, specifically developed for analysis of pressure distributions in cerebral arteries, novel methods were proposed for assessing patients with symptomatic carotid stenosis in the planning of carotid surgery.
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| 9. |
- Holmgren, Madelene, et al.
(författare)
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Assessment of Cerebral Blood Flow Pulsatility and Cerebral Arterial Compliance With 4D Flow MRI
- 2020
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley-Blackwell. - 1053-1807 .- 1522-2586. ; 51:5, s. 1516-1525
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Four-dimensional flow magnetic resonance imaging (4D flow MRI) enables efficient investigation of cerebral blood flow pulsatility in the cerebral arteries. This is important for exploring hemodynamic mechanisms behind vascular diseases associated with arterial pulsations.PURPOSE: To investigate the feasibility of pulsatility assessments with 4D flow MRI, its agreement with reference two-dimensional phase-contrast MRI (2D PC-MRI) measurements, and to demonstrate how 4D flow MRI can be used to assess cerebral arterial compliance and cerebrovascular resistance in major cerebral arteries.STUDY TYPE: Prospective.SUBJECTS: Thirty-five subjects (20 women, 79 ± 5 years, range 70-91 years).FIELD STRENGTH/SEQUENCE: 4D flow MRI (PC-VIPR) and 2D PC-MRI acquired with a 3T scanner.ASSESSMENT: Time-resolved flow was assessed in nine cerebral arteries. From the pulsatile flow waveform in each artery, amplitude (ΔQ), volume load (ΔV), and pulsatility index (PI) were calculated. To reduce high-frequency noise in the 4D flow MRI data, the flow waveforms were low-pass filtered. From the total cerebral blood flow, total PI (PItot ), total volume load (ΔVtot ), cerebral arterial compliance (C), and cerebrovascular resistance (R) were calculated.STATISTICAL TESTS: Two-tailed paired t-test, intraclass correlation (ICC).RESULTS: There was no difference in ΔQ between 4D flow MRI and the reference (0.00 ± 0.022 ml/s, mean ± SEM, P = 0.97, ICC = 0.95, n = 310) with a cutoff frequency of 1.9 Hz and 15 cut plane long arterial segments. For ΔV, the difference was -0.006 ± 0.003 ml (mean ± SEM, P = 0.07, ICC = 0.93, n = 310) without filtering. Total R was 11.4 ± 2.41 mmHg/(ml/s) (mean ± SD) and C was 0.021 ± 0.009 ml/mmHg (mean ± SD). ΔVtot was 1.21 ± 0.29 ml (mean ± SD) with an ICC of 0.82 compared with the reference. PItot was 1.08 ± 0.21 (mean ± SD).DATA CONCLUSION: We successfully assessed 4D flow MRI cerebral arterial pulsatility, cerebral arterial compliance, and cerebrovascular resistance. Averaging of multiple cut planes and low-pass filtering was necessary to assess accurate peak-to-peak features in the flow rate waveforms.LEVEL OF EVIDENCE: 2Technical Efficacy Stage: 2
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| 10. |
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| 11. |
- Holmgren, Madelene, et al.
(författare)
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Diagnostic separation of conventional ⩾50% carotid stenosis and near-occlusion with phase-contrast MRI
- 2024
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Ingår i: European Stroke Journal. - : Sage Publications. - 2396-9873 .- 2396-9881. ; 9:1, s. 135-143
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The aim of this study was to assess sensitivity, specificity and interrater reliability of phase-contrast MRI (PC-MRI) for diagnosing carotid near-occlusion. Patients and methods: Prospective cross-sectional study conducted between 2018 and 2021. We included participants with suspected 50%–100% carotid stenosis on at least one side, all were examined with CT angiography (CTA) and PC-MRI and both ICAs were analyzed. Degree of stenosis on CTA was the reference test. PC-MRI-based blood flow rates in extracranial ICA and intracranial cerebral arteries were assessed. ICA-cerebral blood flow (CBF) ratio was defined as ICA divided by sum of both ICAs and Basilar artery. Results: We included 136 participants. The ICAs were 102 < 50% stenosis, 88 conventional ⩾50% stenosis (31 with ⩾70%), 49 near-occlusion, 12 occlusions, 20 unclear cause of small distal ICA on CTA and one excluded. For separation of near-occlusion and conventional stenoses, ICA flow rate and ICA-CBF ratio had the highest area under the curve (AUC; 0.98–0.99) for near-occlusion. ICA-CBF ratio ⩽0.225 was 90% (45/49) sensitive and 99% (188/190) specific for near-occlusion. Inter-rater reliability for this threshold was excellent (kappa 0.98). Specificity was 94% (29/31) for cases with ⩾70% stenosis. PC-MRI had modest performance for separating <50% and conventional ⩾50% stenosis (highest AUC 0.74), and eight (16%) of near-occlusions were not distinguishable from occlusion (no visible flow). Conclusion: ICA-CBF ratio ⩽0.225 on PC-MRI is an accurate and reliable method to separate conventional ⩾50% stenosis and near-occlusion that is feasible for routine use. PC-MRI should be considered further as a potential standard method for near-occlusion detection, to be used side-by-side with established modalities as PC-MRI cannot separate other degrees of stenosis.
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| 12. |
- Holmgren, Madelene, et al.
(författare)
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Middle cerebral artery pressure laterality in patients with symptomatic ICA stenosis
- 2021
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 16:1
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Tidskriftsartikel (refereegranskat)abstract
- An internal carotid artery (ICA) stenosis can potentially decrease the perfusion pressure to the brain. In this study, computational fluid dynamics (CFD) was used to study if there was a hemispheric pressure laterality between the contra- and ipsilateral middle cerebral artery (MCA) in patients with a symptomatic ICA stenosis. We further investigated if this MCA pressure laterality (ΔPMCA) was related to the hemispheric flow laterality (ΔQ) in the anterior circulation, i.e., ICA, proximal MCA and the proximal anterior cerebral artery (ACA). Twenty-eight patients (73±6 years, range 59–80 years, 21 men) with symptomatic ICA stenosis were included. Flow rates were measured using 4D flow MRI data (PC-VIPR) and vessel geometries were obtained from computed tomography angiography. The ΔPMCA was calculated from CFD, where patient-specific flow rates were applied at all input- and output boundaries. The ΔPMCA between the contra- and ipsilateral side was 6.4±8.3 mmHg (p<0.001) (median 3.9 mmHg, range -1.3 to 31.9 mmHg). There was a linear correlation between the ΔPMCA and ΔQICA (r = 0.85, p<0.001) and ΔQACA (r = 0.71, p<0.001), respectively. The correlation to ΔQMCA was weaker (r = 0.47, p = 0.011). In conclusion, the MCA pressure laterality obtained with CFD, is a promising physiological biomarker that can grade the hemodynamic disturbance in patients with a symptomatic ICA stenosis.
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| 13. |
- Holmgren, Madelene, et al.
(författare)
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Phase-contrast magnetic resonance imaging of intracranial and extracranial blood flow in carotid near-occlusion
- 2024
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Ingår i: NEURORADIOLOGY. - : Springer Nature. - 0028-3940 .- 1432-1920.
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Tidskriftsartikel (refereegranskat)abstract
- Purpose Compare extracranial internal carotid artery flow rates and intracranial collateral use between conventional >= 50% carotid stenosis and carotid near-occlusion, and between symptomatic and asymptomatic carotid near-occlusion. Methods We included patients with >= 50% carotid stenosis. Degree of stenosis was diagnosed on CTA. Mean blood flow rates were assessed with four-dimensional phase-contrast MRI. Results We included 110 patients of which 83% were symptomatic, and 38% had near-occlusion. Near-occlusions had lower mean internal carotid artery flow (70 ml/min) than conventional >= 50% stenoses (203 ml/min, P < .001). Definite use of >= 1 collateral was found in 83% (35/42) of near-occlusions and 10% (7/68) of conventional stenoses (P < .001). However, there were no differences in total cerebral blood flow (514 ml/min vs. 519 ml/min, P = .78) or ipsilateral hemispheric blood flow (234 vs. 227 ml/min, P = .52), between near-occlusions and conventional >= 50% stenoses, based on phase-contrast MRI flow rates. There were no differences in total cerebral or hemispheric blood flow, or collateral use, between symptomatic and asymptomatic near-occlusions. Conclusion Near-occlusions have lower internal carotid artery flow rates and more collateral use, but similar total cerebral blood flow and hemispheric blood flow, compared to conventional >= 50% carotid stenosis.
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| 14. |
- Holmgren, Madelene, et al.
(författare)
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Prediction of cerebral perfusion pressure during carotid surgery : A computational fluid dynamics approach
- 2022
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Ingår i: Clinical Biomechanics. - : Elsevier BV. - 0268-0033 .- 1879-1271. ; 100
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Tidskriftsartikel (refereegranskat)abstract
- Background: Maintaining cerebral perfusion pressure in the brain when a carotid artery is closed during vascular surgery is critical for avoiding intraoperative hypoperfusion and risk of ischemic stroke. Here we propose and evaluate a method based on computational fluid dynamics for predicting patient-specific cerebral perfusion pressures at carotid clamping during carotid endarterectomy.Methods: The study consisted of 22 patients with symptomatic carotid stenosis who underwent carotid endarterectomy (73 ± 5 years, 59–80 years, 17 men). The geometry of the circle of Willis was obtained preoperatively from computed tomography angiography and corresponding flow rates from four-dimensional flow magnetic resonance imaging. The patients were also classified as having a present or absent ipsilateral posterior communicating artery based on computed tomography angiography. The predicted mean stump pressures from computational fluid dynamics were compared with intraoperatively measured stump pressures from carotid endarterectomy.Findings: On group level, there was no difference between the predicted and measured stump pressures (−0.5 ± 13 mmHg, P = 0.86) and the pressures were correlated (r = 0.44, P = 0.039). Omitting two outliers, the correlation increased to r = 0.78 (P < 0.001) (−1.4 ± 8.0 mmHg, P = 0.45). Patients with a present ipsilateral posterior communicating artery (n = 8) had a higher measured stump pressure than those with an absent artery (n = 12) (P < 0.001).Interpretation: The stump pressure agreement indicates that the computational fluid dynamics approach was promising in predicting cerebral perfusion pressures during carotid clamping, which may prove useful in the preoperative planning of vascular interventions.
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| 15. |
- Jonsson, Anders, et al.
(författare)
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Evaluating a large-scale implementation of Assessment for Learning in Sweden
- 2015
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Ingår i: Assessment in education. - : Routledge. - 0969-594X .- 1465-329X. ; 22:1, s. 104-121
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Tidskriftsartikel (refereegranskat)abstract
- This study reports on a large-scale implementation of Assessment for Learning (AfL) in a Swedish municipality. The implementation was founded on two principles: (1) teaching should be informed by educational research; (2) to be successful teachers' professional development needs to be based in everyday classroom practice. From these principles, AfL was chosen as a strand of educational research to inform teaching and 'Teacher Learning Communities' were chosen as a vehicle for professional development and for implementing AfL practices. Findings indicate that the project has been successful in bringing about a change in how teachers talk about teaching and learning and in changing teachers' pedagogical practice towards AfL. Findings also suggest that AfL practices are mostly teacher-centred, which means that the teachers still take most of the responsibility for the assessment. This leads to high workload for the teachers and may also hinder students from taking responsibility for their learning.
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| 16. |
- Jönsson, Anders, et al.
(författare)
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Evaluating a large-scale implementation of assessment for learning in Sweden
- 2014
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Konferensbidrag (refereegranskat)abstract
- This study reports on a large-scale implementation of Assessment for Learning (AfL) in a Swedish municipality. The implementation was founded on two principles: (1) teaching should be informed by educational research; (2) to be successful, teachers’ professional development needs to be based in every-day classroom practice. From these principles, AfL was chosen as a strand of educational research to inform teaching and ‘Teacher Learning Communities’ were chosen as a vehicle for professional development and for implementing AfL practices. Findings indicate that the project has been successful in bringing about a change in how teachers’ talk about teaching and learning and in changing teachers’ pedagogical practice towards AfL. Findings also suggest that AfL practices are mostly teacher centred, which means that the teachers still take most of the responsibility for the assessment. This leads to high workload for the teachers and may also hinder students from taking responsibility for their learning.
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| 17. |
- Liljeström, Monica, et al.
(författare)
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How will they react if we make them talk? : Students’ experiences from learner-created video tasks in online university education in Sweden
- 2017
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Ingår i: ICICTE 2017 Proceedings. - Rhodes, Greece : ICICTE 2017. - 9780993288982 ; , s. 318-328, s. 318-328
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Konferensbidrag (refereegranskat)abstract
- In focus in this paper are students’ views on their experiences of an educational design with oral assessment tasks supported by video technology in online university education in Sweden. Questions targeted how the students perceived the impact of oral tasks on their learning. The data were gathered through questionnaires, qualitative interviews and students’ self-reflection documents. Results indicate most students appreciated the oral assessments, and their descriptions of this learning experience indicate that the studied video-based task-design may enhance online students’ learning experiences.
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| 18. |
- Nilsson, Daniel, et al.
(författare)
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Patient-specific brain arteries molded as a flexible phantom model using 3D printed water-soluble resin
- 2022
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 12
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Tidskriftsartikel (refereegranskat)abstract
- Visualizing medical images from patients as physical 3D models (phantom models) have many roles in the medical field, from education to preclinical preparation and clinical research. However, current phantom models are generally generic, expensive, and time-consuming to fabricate. Thus, there is a need for a cost- and time-efficient pipeline from medical imaging to patient-specific phantom models. In this work, we present a method for creating complex 3D sacrificial molds using an off-the-shelf water-soluble resin and a low-cost desktop 3D printer. This enables us to recreate parts of the cerebral arterial tree as a full-scale phantom model (10×6×410×6×4 cm) in transparent silicone rubber (polydimethylsiloxane, PDMS) from computed tomography angiography images (CTA). We analyzed the model with magnetic resonance imaging (MRI) and compared it with the patient data. The results show good agreement and smooth surfaces for the arteries. We also evaluate our method by looking at its capability to reproduce 1 mm channels and sharp corners. We found that round shapes are well reproduced, whereas sharp features show some divergence. Our method can fabricate a patient-specific phantom model with less than 2 h of total labor time and at a low fabrication cost.
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| 19. |
- Nilsson, Åsa, et al.
(författare)
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Modellering av råvaruflödet i skogliga värdekedjor, inklusive råvaruegenskaper och hållbarhetsaspekter
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detta är en delrapport från programmet Mistra Digital Forest. Rapporten beskriver den inledande utvecklingen av verktyget BioMapp. Vidare beskrivs vilka digitala data som kan användas som indata för att driva simuleringar med verktyget samt hur den fortsatta utvecklingen planeras inom Mistra Digital Forest. BioMapp är tänkt att användas för att bidra till en ökad förståelse av hur den skogliga råvaran fördelas på olika produktgrupper, samt för att beräkna ett antal hållbarhetsindikatorer för varje steg i förädlingsprocessen. Dessutom ska BioMapp kunna visualisera och beräkna effekter av ändrade strategier i råvaruförsörjningen, tex om flödet av skogsråvara styrs till industrikunden baserat på ved- och fiberegenskaper i högre grad än i dag.
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| 20. |
- Persson, Gunnar, et al.
(författare)
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1 b, urval och representativitet
- 2009
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Ingår i: Rapport / Naturvårdsverket. - 0282-7298. ; , s. 105-116
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Annan publikation (övrigt vetenskapligt/konstnärligt)
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| 21. |
- Sandström, Alfred, et al.
(författare)
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Assessing the potential of remote sensing-derived water quality data to explain variations in fish assemblages and to support fish status assessments in large lakes
- 2016
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 780, s. 71-84
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Tidskriftsartikel (refereegranskat)abstract
- Remote sensing techniques may provide a higher temporal and spatial resolution than traditional water monitoring methods. We tested if this auxiliary information can be used to (i) explain patterns in fish assemblage composition and (ii) test candidate metrics to assess ecological status in large lake water bodies. We used MERIS-derived layers describing chlorophyll a, total suspended matter, and colored dissolved organic matter (CDOM) overlaid on all available fish monitoring data from the four largest Swedish lakes (Vanern, Vattern, Malaren, and Hjalmaren). We assessed the influence of remote sensing-derived parameters in the pelagic, offshore benthic, and the inshore benthic habitats. Our results demonstrated that chlorophyll a and CDOM together with depth at the sampling site explained a significant part of the variation in the distribution of fish assemblages. These predictors were particularly important not only in pelagic, but also in inshore benthic areas. Furthermore, we identified three potential candidate metrics to assess pressure from eutrophication in large lakes: density of pelagic fishes, biomass of planktivorous species, and the proportion of cyprinids when roach was excluded. Remote sensing was considered a useful tool to support analyses of fish community composition and dynamics.
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| 22. |
- Siwe, Ulf, et al.
(författare)
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Sea Traffic Management – Concepts and Components
- 2015
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Ingår i: 14th International Conference on Computer and IT Applications in the Maritime Industries.
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Konferensbidrag (refereegranskat)abstract
- This paper gives an overview of all components making up the Sea Traffic Management (STM) concept. STM builds upon information sharing in the whole maritime transport chain, where informationis shared as early as possible about intentions and reached states. Sea System Wide Information Management will provide an infrastructure for a regulated and federated approach to informationsharing. The functional sub-concepts are described: Strategic Voyage Management, Dynamic Voyage Management, Flow Management and Port Cooperative Decision Making. We will elaborate on how they complement each other and which benefits each of them has in regards to safety, environment and efficiency
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| 23. |
- Vikner, Tomas, et al.
(författare)
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Characterizing pulsatility in distal cerebral arteries using 4D flow MRI
- 2020
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Ingår i: Journal of Cerebral Blood Flow and Metabolism. - : Sage Publications. - 0271-678X .- 1559-7016. ; 40:12, s. 2429-2440
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Tidskriftsartikel (refereegranskat)abstract
- Recent reports have suggested that age-related arterial stiffening and excessive cerebral arterial pulsatility cause blood-brain barrier breakdown, brain atrophy and cognitive decline. This has spurred interest in developing non-invasive methods to measure pulsatility in distal vessels, closer to the cerebral microcirculation. Here, we report a method based on four-dimensional (4D) flow MRI to estimate a global composite flow waveform of distal cerebral arteries. The method is based on finding and sampling arterial waveforms from thousands of cross sections in numerous small vessels of the brain, originating from cerebral cortical arteries. We demonstrate agreement with internal and external reference methods and show the ability to capture significant increases in distal cerebral arterial pulsatility as a function of age. The proposed approach can be used to advance our understanding regarding excessive arterial pulsatility as a potential trigger of cognitive decline and dementia.
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| 24. |
- Vikström, Axel, et al.
(författare)
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Establishing the distribution of cerebrovascular resistance using computational fluid dynamics and 4D flow MRI
- 2024
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Cerebrovascular resistance (CVR) regulates blood flow in the brain, but little is known about the vascular resistances of the individual cerebral territories. We present a method to calculate these resistances and investigate how CVR varies in the hemodynamically disturbed brain. We included 48 patients with stroke/TIA (29 with symptomatic carotid stenosis). By combining flow rate (4D flow MRI) and structural computed tomography angiography (CTA) data with computational fluid dynamics (CFD) we computed the perfusion pressures out from the circle of Willis, with which CVR of the MCA, ACA, and PCA territories was estimated. 56 controls were included for comparison of total CVR (tCVR). CVR were 33.8 ± 10.5, 59.0 ± 30.6, and 77.8 ± 21.3 mmHg s/ml for the MCA, ACA, and PCA territories. We found no differences in tCVR between patients, 9.3 ± 1.9 mmHg s/ml, and controls, 9.3 ± 2.0 mmHg s/ml (p = 0.88), nor in territorial CVR in the carotid stenosis patients between ipsilateral and contralateral hemispheres. Territorial resistance associated inversely to territorial brain volume (p < 0.001). These resistances may work as reference values when modelling blood flow in the circle of Willis, and the method can be used when there is need for subject-specific analysis.
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| 39. |
- Aase, Karin, et al.
(författare)
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Angiomotin regulates endothelial cell migration during embryonic angiogenesis
- 2007
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Ingår i: Genes & Development. - : Cold Spring Harbor Laboratory. - 0890-9369 .- 1549-5477. ; 21:16, s. 2055-2068
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Tidskriftsartikel (refereegranskat)abstract
- The development of the embryonic vascular system into a highly ordered network requires precise control over the migration and branching of endothelial cells (ECs). We have previously identified angiomotin (Amot) as a receptor for the angiogenesis inhibitor angiostatin. Furthermore, DNA vaccination targeting Amot inhibits angiogenesis and tumor growth. However, little is known regarding the role of Amot in physiological angiogenesis. We therefore investigated the role of Amot in embryonic neovascularization during zebrafish and mouse embryogenesis. Here we report that knockdown of Amot in zebrafish reduced the number of filopodia of endothelial tip cells and severely impaired the migration of intersegmental vessels. We further show that 75% of Amot knockout mice die between embryonic day 11 (E11) and E11.5 and exhibit severe vascular insufficiency in the intersomitic region as well as dilated vessels in the brain. Furthermore, using ECs differentiated from embryonic stem (ES) cells, we demonstrate that Amot-deficient cells have intact response to vascular endothelial growth factor (VEGF) in regard to differentiation and proliferation. However, the chemotactic response to VEGF was abolished in Amot-deficient cells. We provide evidence that Amot is important for endothelial polarization during migration and that Amot controls Rac1 activity in endothelial and epithelial cells. Our data demonstrate a critical role for Amot during vascular patterning and endothelial polarization.
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| 40. |
- Abdiu, Avni, 1963-, et al.
(författare)
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Thioredoxin blood level increases after severe burn injury
- 2000
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Ingår i: Antioxidants and Redox Signaling. - 1523-0864 .- 1557-7716. ; 2:4, s. 707-716
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the thioredoxin (TRX) levels in severely burned patients and the possible origin of TRX, based on the recent understanding that TRX is a potent antioxidant with cytoprotective functions. Serum and plasma samples from burns patients and healthy blood donors were collected during the first 10 post-bum days and analyzed in a sandwich TRX enzyme-linked immunosorbent assay (ELISA). The TRX levels found were correlated to a panel of blood tests. The presence of TRX in platelets was investigated by immunoelectron microscopy and Western blotting. TRX serum levels of the severely burned patients showed a significant increase, with a mean serum TRX concentration on the day of injury of 76.5 ▒ 19.5 ng/ml (mean ▒ SD) and on post-burn day one 122.6 ▒ 66.9 ng/ml, compared to control blood donor levels of 22.7 ▒ 12.2 ng/ml (p = 0.0041 and 0.0117, respectively). A second peak of increase was found on post-burn days 7 to 9 with a four- to five-fold rise in concentration compared to controls. TRX elevation correlated well with increased platelet (p = 0.007) and leukocyte counts (p = 0.002). We also demonstrated by immunoelectron microscopy and Western blotting the presence of TRX in platelets. In conclusion, our demonstration of TRX release in burn injuries indicates that the TRX system is involved in a rapid antioxidant defense, coagulation processes, cell growth, and control of the extracellular peroxide tone intimately linked to cytoprotection and wound healing in burns. One of the cell types that delivers TRX promptly and efficiently into the blood may be the platelet.
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| 41. |
- Ahlford, Marianne, et al.
(författare)
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Uppsala Underdogs - A Robot Soccer Project
- 2006
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Rapport (populärvet., debatt m.m.)abstract
- In this paper, we describe the four-legged soccer team Uppsala Underdogs developed by a group of 4th year computer science students at Uppsala University during the fall of 2004. The project is based on the experience from two similar previous projects. This year the emphasis of the project has been on distribution of data and on support for evaluation and reconfiguration of strategies. To support data distribution, a middleware has been developed, which implements a replication algorithm and provides a clean interface for the other software modules (or behaviors). To enable easy reconfiguration of strategies, an automata-based graphical description language has been developed, which can be compiled into code that uses the database and the lower level modules, such as tactics and positioning, to make decisions and control the robot. In addition, a graphical simulator has been developed in which the strategies can be evaluated.
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| 44. |
- Almqvist, Gustaf, et al.
(författare)
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Report of the Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD)
- 2015
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ICES Benchmark Workshop on Baltic Cod Stocks (WKBALTCOD), chaired by External Chair Jean-Jacques Maguire, Canada and ICES Chair Marie Storr-Paulsen, Denmark, and attended by two invited external experts Verena Trenkel, France and Meaghan Bryan, USA met in Rostock, Germany, 2–6 March 2015 with 39 participants and six countries represented. The objective of WKBALTCOD was to evaluate the appropriateness of data and methods to determine stock status and investigate meth-ods appropriate to use in the single-stock assessment for the cod stock in SD 22–24 and cod in SD 25–32 in the Baltic. Participants in the workshop were a large group with diverse backgrounds representing the industry, fisheries, NGOs, managers and scientists.The single-stock analytic assessment of the eastern Baltic stock was not accepted by the assessment working group (WGBFAS) in 2014 due to severe problems with the input data. The advice for the eastern Baltic cod was, therefore, based on the ICES approach for data-limited stocks. As an outcome ICES decided to establish a bench-mark for both cod stocks and to scope an integrated assessment for the Baltic cod stocks. The first meeting (WKSIBCA) was therefore meant to introduce the interces-sional work conducted since the assessment working group in April 2014, and to reach some conclusions on how to proceed both in the short term (Benchmark in March 2015) and longer term (2–3 years) and was seen as a data compilation work-shop, there is produced a separate report from this workshop. The WKBALTCOD was the 2nd meeting in the benchmark process and was intended to come up with a final stock assessment method, stock annex and input data for both stocks. As it was not possible to reach conclusive decision on the final model to be used for the east Baltic cod stock during the benchmark meeting and as more work on the preferable models was needed, it was decided by the ACOM leadership to prolong the bench-mark process until the assessment working group meeting in April 2015. This deci-sion has led to a relatively long process partly mixed with the assessment working group WGBFAS.It became clear during the benchmark process that although large effort has been put into explaining the underlying processes leading to the changes in the Baltic ecosys-tem, there is still some lack of understanding of the present situation in the eastern Baltic cod stock. Therefore, it was not possible to reach firm conclusions on the final model to be used and therefore not possible to set reference points. It was decided to continue to explore the most promising models and to continue to improve the input data until the assessment working group started in April.The main challenges still to be solved for the Eastern Baltic cod stock is the quantifi-cation of increased natural mortality and decrease in growth. Through several presentations during the workshop (both WKSIBCA and WKBALTCOD) it became clear that natural mortality very likely has increased in later years, due to decreased condition and increased parasite infection. A decrease in growth also seems plausible duo to a decrease in condition and/or selectivity-induced mortality of the largest in-dividuals. However, as none of these parameters are easily estimated, especially with the severe ageing problems, different model assumptions made the output very shaky.For the western Baltic cod, stock identification issues were examined in area SD 24, the intermediate area: based on otolith characteristics and genetics. Due to the results showing a large proportion of east cod in this area, it was decided to split the catch2 | ICES WKBALTCOD REPORT 2015and survey from SD 24 into either the western or eastern Baltic cod stock. It was pos-sible to derive proportions of eastern and western cod in SD 24 back to the mid-1990s.For the western Baltic cod stock a modelled survey indices was included in the as-sessment covering the western part of SD 24 and Area 22+23 and based on a smoothed ALK.Both cod stocks have in the past used commercial tuning fleet to have a better cov-ered of older age groups. It was decided to abound this time-series duo quality issues such as a limited coverage and problems with technical creeping.WKBALTCOD was not able to explore and define reference points for the Western Baltic cod stock during the meeting due to time constraints, but these were calculated and decided by correspondence after the meeting. The recent protocols on estimation procedures developed by WKMSYREF3 for stocks with a full analytical assessment and for data-limited stocks served as objective guidelines to obtain reference point estimates.
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| 45. |
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| 46. |
- Ansell, Anders, et al.
(författare)
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Betongkonstruktioner
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 47. |
- Ansell, Anders, et al.
(författare)
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Concrete Structures
- 2012
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Rapport (övrigt vetenskapligt/konstnärligt)
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| 48. |
- Ansell, Anders, et al.
(författare)
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Dynamically loaded young shotcrete linings
- 2001
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Ingår i: Shotcrete: Engineering developments. - Lisse : Swets & Zeitlinger. - 90 5809 176 7 ; , s. 33-40
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Konferensbidrag (refereegranskat)
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