| 1. |
- Holmqvist, Fredrik, et al.
(författare)
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A decade of catheter ablation of cardiac arrhythmias in Sweden : ablation practices and outcomes
- 2019
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Ingår i: European Heart Journal. - : Oxford University Press (OUP). - 0195-668X .- 1522-9645. ; 40:10, s. 820-830
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Catheter ablation is considered the treatment of choice for many tachyarrhythmias, but convincing 'real-world' data on efficacy and safety are lacking. Using Swedish national registry data, the ablation spectrum, procedural characteristics, as well as ablation efficacy and reported adverse events are reported.Methods and Results: Consecutive patients (≥18 years of age) undergoing catheter ablation in Sweden between 01 January 2006 and 31 December 2015 were included in the study. Follow-up (repeat ablation and vital status) was collected through 31 December 2016. A total of 26 642 patients (57 ± 15 years, 62% men), undergoing a total of 34 428 ablation procedures were included in the study. In total, 4034 accessory pathway/Wolff-Parkinson-White syndrome (12%), 7358 AV-nodal re-entrant tachycardia (21%), 1813 atrial tachycardia (5.2%), 5481 typical atrial flutter (16%), 11 916 atrial fibrillation (AF, 35%), 2415 AV-nodal (7.0%), 581 premature ventricular contraction (PVC, 1.7%), and 964 ventricular tachycardia (VT) ablations (2.8%) were performed. Median follow-up time was 4.7 years (interquartile range 2.7-7.0). The spectrum of treated arrhythmias changed over time, with a gradual increase in AF, VT, and PVC ablation (P < 0.001). Decreasing procedural times and utilization of fluoroscopy with time, were seen for all arrhythmia types. The rates of repeat ablation differed between ablation types, with the highest repeat ablation seen in AF (41% within 3 years). The rate of reported adverse events was low (n = 595, 1.7%). Death in the immediate period following ablation was rare (n = 116, 0.34%).Conclusion: Catheter ablations have shifted towards more complex procedures over the past decade. Fluoroscopy time has markedly decreased and the efficacy of catheter ablation seems to improve for AF.
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| 2. |
- Holmqvist, Fredrik, et al.
(författare)
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Increasing Ablation Volumes And A Shift Towards More Complex Arrhythmias : Data From The Swedish National Catheter Ablation Registry
- 2018
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Konferensbidrag (refereegranskat)abstract
- Background: Catheter ablation has become the treatment of choice for many tachyarrhythmias. The ablation techniques are continuously refined and the indications expanded, enabling treatment of more complex substrates. Hence, the spectrum of treated arrhythmias is likely to have changed over time, but compelling data on this are lacking.Objective: The present study set out to explore the changing pattern of ablations performed in the setting of a universal, single-payer healthcare system, using data from the Swedish national catheter ablation registry.Methods: The Swedish National Catheter Ablation Registry covers virtually all (>97%) catheter ablations performed in Sweden since 2005 and comprises 42,192 ablations on 32,237 individual patients. In the present analysis, all ablations performed between 2005 and 2016 were included.Results: In 2005, there were 7 ablation centers in Sweden performing a total of 1,584 ablations (226/center; 175/million). In 2016, 11 ablation centers performed 5,022 ablations (457/center; 502/million). Ablation of atrial fibrillation increased from 326 ablations (21% of all) in 2005 to 2,063 (41%) in 2016. Although, the number of ablation procedures for ventricular tachycardia and premature ventricular contractions is increasing, it is still on a relatively modest level (Figure). In contrast to other reports, there is no apparent decline in the number of accessory pathway ablations.Conclusion: In the setting of a universal, single-payer healthcare system, the number of ablations more than tripled over a 10-year period. Ablation of atrial fibrillation is the main driver behind this increase and accounted for 41% of all ablations in Sweden in 2016.
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| 3. |
- Själander, Sara, et al.
(författare)
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Assessment of Use vs Discontinuation of Oral Anticoagulation After Pulmonary Vein Isolation in Patients With Atrial Fibrillation
- 2017
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Ingår i: JAMA cardiology. - : American Medical Association. - 2380-6583 .- 2380-6591. ; 2:2, s. 146-152
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE: Pulmonary vein isolation (PVI) is a recommended treatment for patients with atrial fibrillation, but it is unclear whether it results in a lower risk of stroke.OBJECTIVES: To investigate the proportion of patients discontinuing anticoagulation treatment after PVI in association with the CHA(2)DS(2)-VASc (congestive heart failure, hypertension, age >= 75 years [doubled], diabetes, stroke [doubled], vascular disease, age 65-74 years, sex category [female]) score, identify factors predicting stroke after PVI, and explore the risk of cardiovascular events after PVI in patients with and without guideline-recommended anticoagulation treatment.DESIGN, SETTING, AND PARTICIPANTS: A retrospective cohort studywas conducted using Swedish national health registries from January 1, 2006, to December 31, 2012, with a mean-follow up of 2.6 years. A total of 1585 patients with atrial fibrillation undergoing PVI from the Swedish Catheter Ablation Register were included, with information about exposure to warfarin in the national quality register Auricula. Data analysis was performed from January 1, 2015, to April 30, 2016.EXPOSURES: Warfarin treatment.MAIN OUTCOMES AND MEASURES: Ischemic stroke, intracranial hemorrhage, and death.RESULTS: In this cohort of 1585 patients, 73.0% were male, the mean (SD) age was 59.0 (9.4) years, and the mean (SD) CHA(2)DS(2)-VASc score was 1.5 (1.4). Of the 1585 patients, 1175 were followed up for more than 1 year after PVI. Of these, 360 (30.6%) discontinued warfarin treatment during the first year. In patients with a CHA(2)DS(2)-VASc score of 2 or more, patients discontinuing warfarin treatment had a higher rate of ischemic stroke (5 events in 312 years at risk [1.6% per year]) compared with those continuing warfarin treatment (4 events in 1192 years at risk [0.3% per year]) (P = .046). Patients with a CHA(2)DS(2)-VASc score of 2 or more or those who had previously experienced an ischemic stroke displayed a higher risk of stroke if warfarin treatment was discontinued (hazard ratio, 4.6; 95% CI, 1.2-17.2; P = .02 and hazard ratio, 13.7; 95% CI, 2.0-91.9; P = .007, respectively).CONCLUSIONS AND RELEVANCE: These findings indicate that discontinuation ofwarfarin treatment after PVI is not safe in high-risk patients, especially those who have previously experienced an ischemic stroke.
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| 4. |
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| 5. |
- Ahlin, Cecilia, et al.
(författare)
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Aberrant expression of cyclin E in low-risk node negative breast cancer
- 2008
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Ingår i: Acta Oncologica. - : Informa UK Limited. - 0284-186X .- 1651-226X. ; 47:8, s. 1539-1545
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Tidskriftsartikel (refereegranskat)abstract
- Background. Cyclin E is a cell cycle regulatory protein which occurs in G1, peaks in late G1 and is degraded in early S-phase. Cyclin E overexpression appears to be an independent prognostic factor for overall survival in breast cancer. Material and Methods. Nuclear cyclin A is a reliable marker for S-and G2-phases. Consequently, aberrant expression of cyclin E can be detected by simultaneous immunostainings for cyclin A and cyclin E. Studies have shown that aberrant cyclin E might provide additional prognostic information compared to that of cyclin E alone. This study aimed to investigate cyclin E and aberrant cyclin E expression in low-risk node negative breast cancer. We compared women that died from their breast cancer (n=17) with women free from relapse>8 years after initial diagnosis (n=24). All women had stage I, low risk breast cancer. The groups were matched regarding tumour size, receptor status, adjuvant chemotherapy and tumour differentiation. Tumour samples were analysed regarding expression of cyclin A, cyclin E and double-stained tumour cells using immunoflourescence staining and digital microscopy. Results. No differences were seen regarding expression of cyclin E or aberrant cyclin E in cases compared to controls. Discussion. We conclude that neither cyclin E nor aberrant cyclin E is a prognostic factor in low-risk node negative breast cancer patients.
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| 6. |
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| 7. |
- Bergvall, Anders, 1981, et al.
(författare)
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Basic Theory of Electron Transport Through Molecular Contacts
- 2016
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Ingår i: Handbook of Single-Molecule Electronics. - 9789814463393 ; , s. 31-78
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In this chapter, we will introduce a basic theoretical description of coherent electron transport through low-dimensional junctions and molecular devices. The description introduced is based on quantum transport theory using a tight-binding description of molecules and lead materials. We apply this theory in a few worked examples on junctions based on graphene and carbon nanotubes and on molecular-superconducting hybrid junctions.
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| 8. |
- Björkman, John, 1978-
(författare)
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"Må de herrskande klasserna darra" : Radikal retorik och reaktion i Stockholms press, 1848-1851
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This dissertation explores the formation of the modern historiography of class in mid-nineteenth century Sweden by analyzing constitutive rhetoric of class in the Stockholm press from 1848 to 1851. The aim is to study how disparaged workers during the February Revolution in France began to be ascribed a new kind of unified agency, and how workers in Stockholm became recipients of mobilizing appeals from all parts of the political spectrum. To this end the dissertation examines periodical papers representing the three major political positions of the period, i.e. a royalist conservative press, liberal papers in opposition, and a newly emerging socialist press. How were workers described, invoked and addressed as a new kind of community of political interest and action in these publications?Refuting perspectives of socio-economic determinism, this study adopts a conception of belonging and agency that views political communities as discursively produced by the creation of subject positions and the interpellation of individuals to them. The study is also influenced by recent re-evaluations of the category of the event associated with poststructuralism, and analyzes operations of constitutive rhetoric in forming a new symbolic field of class identity and agency in an open-ended and multivalent historical situation.The analysis shows how workers were construed as political agents in the Stockholm press during the mid-nineteenth century turmoil by being described, invoked and addressed within the framework of four main rival narratives. The socialist press tried to evoke a self-organizing working class within a collectivist narrative of labour’s liberation and universal male suffrage. The liberal press interpellated workers to a position aligned with the reformist middle class within a narrative of individual self-determination and gradual improvement. The royalist narrative of reconciliation was aimed at separating the large mass of workers from socialist and communist ideologues, deemed as mischievous outsiders, while at the same time offering them a new-found and prominent role as protectors of social harmony and peace. Only within the royalist narrative of catastrophe were the workers continuously excluded from mobilizing appeals, instead being invoked as the harbingers of an approaching communist revolution, against which all other sections of society should unite.
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| 9. |
- Bollmann, Andreas, et al.
(författare)
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Atrial fibrillatory rate and risk of left atrial thrombus in atrial fibrillation.
- 2007
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 9:8, s. 6-621
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Tidskriftsartikel (refereegranskat)abstract
- ims In atrial fibrillation (AF), a relation between electrocardiogram (ECG) fibrillatory wave amplitude and thrombus formation has been sought for long with conflicting results. In contrast, the possible relation between atrial fibrillatory rate obtained from the surface ECG and left atrial thrombus formation in patients with AF is unknown and was consequently evaluated in this study. Methods and results One-hundred and twenty-five patients (mean age 64 ± 12 years, 72% male) with persistent non-valvular AF (mean duration 28 ± 80 days) undergoing transesophageal echocardiography were studied. In all patients, standard 12-lead ECG recordings were acquired before the examination. Atrial fibrillatory rate was determined using spatiotemporal QRST cancellation and time–frequency analysis of lead V1. Atrial fibrillatory rate measured 401 ± 63 fibrillations per minute (fpm, range 235–566 fpm) and was related with age (R = −0.326, P < 0.001), ventricular rate (R = −0.202, P = 0.024), gender (407 ± 62 in males vs. 387 ± 64 fpm in females, P = 0.038) but not AF duration (R = 0.088, P = 0.374), presence of lone AF (408 ± 66 vs. 394 ± 58 fpm, P = 0.228), or beta-blocker or calcium channel blocker treatment (398 ± 63 vs. 405 ± 62 fpm, P = 0.556). Age was the only independent predictor of fibrillatory rate (B = −1.714, P < 0.001). In patients with left atrial thrombus (n = 10), spontaneous echo contrast (SEC) was more frequently present (70 vs. 29 %, p = 0.007) and left atrial appendage (LAA) outflow velocity was lower (26 ± 20 vs. 37 ± 15 cm/s, P = 0.012) than in patients without thrombus (n = 115). In contrast, mean fibrillatory rate, which showed a weak inverse correlation with LAA velocity (R = −0.118, P = 0.048) was not different between both groups (380 ± 56 vs. 403 ± 63 fpm, P = 0.226). Similarly, presence of thrombus and SEC combined was not related with fibrillatory rate. Conclusion Atrial fibrillatory rate obtained from surface ECG lead V1 is not a risk marker for left atrial thrombus formation in AF.
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| 10. |
- Burman, Anders, et al.
(författare)
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Introduktion
- 2008
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Ingår i: Lychnos. - Uppsala : Lärdomshistoriska samfundet. - 9789185286584 ; , s. 93-98
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 11. |
- Choudhary, Mariam B, et al.
(författare)
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Low atrial fibrillatory rate is associated with spontaneous conversion of recent-onset atrial fibrillation.
- 2013
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Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 15:10, s. 1445-1452
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: Atrial fibrillatory rate (AFR) is considered a non-invasive index of atrial remodelling. Low AFR has been associated with favourable outcome of interventions in patients with persistent atrial fibrillation (AF). However, AFR has never been studied in unselected patients with short duration of AF, prone to regain sinus rhythm (SR) spontaneously. The aim of the study was to assess if AFR can predict spontaneous conversion in patients with recent-onset AF.METHODS AND RESULTS: Files of consecutive patients with AF < 48 h seeking emergency room care during a 12-month period were screened (n = 225). Patients with thyroid illness, acute ischaemic heart disease (IHD) or acute congestive heart failure, significant valvular heart disease, congenital heart disease, history of cardiac surgery or catheter ablation, or on class I/III antiarrhythmics were excluded. Atrial fibrillatory rate was obtained by QRST cancellation and time frequency analysis of electrocardiogram at admission. The study population comprised 148 patients (age 64 ± 13 years, 52 men), of whom 48 converted to SR within 18 h. Those converting spontaneously comprised more women, had a higher prevalence of first-ever AF episode, IHD, and a lower AFR. The multivariate analysis revealed: AFR < 350 fibrillations per minute [odds ratio (OR) 3.7, 95% confidence interval (CI) 1.3-10.5, P = 0.016], IHD (OR 5.7, 95% CI 1.5-22.4, P = 0.012) and first-ever AF episode (OR 4.1, 95% CI 1.3-13.0, P = 0.015) as independent predictors of spontaneous conversion.CONCLUSION: A low AFR was predictive of spontaneous conversion in patients with recent-onset AF. Along with first-ever AF episode and IHD, AFR can be used in assessing likelihood of spontaneous conversion, if proven in prospective studies.
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| 12. |
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| 13. |
- Eklöf, Anders, et al.
(författare)
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Att bedöma och verka i en digital dimension
- 2011
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Ingår i: Skolan och läraruppdraget. - Lund : Studentlitteratur. ; , s. 99-118
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Digitalt smarta lärare som arbetar med elever som ser det digitala rummet som bara ett av många klassrum behöver förhålla sig till upplösning av såväl tid och rum som arbetsformer. Flera av de sätt vi traditionellt sett har genomfört bedömning på kan komma att kollidera med arbetsformer som introduceras genom möjligheter som den digitala dimensionen erbjuder. Utan en grundligt genomtänkt vetenskapligt förankrad kunskap om möjligheter och problem förknippade med dessa arbetsformer riskerar vi att göra helt felaktiga bedömningar. I slutändan riskerar vi att underkänna eller anklaga eleverna för fusk, bara för att vi egentligen inte förstår de arbetsformer som är naturliga för eleverna. I detta kapitel kommer vi att diskutera uppgifter och bedömningsproblematik främst med utgångspunkt i forskning kring skrivande och bedömning.
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| 14. |
- Eklöf, Anders, et al.
(författare)
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Digitala rum och nya mönster
- 2011
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Ingår i: Skolan och läraruppdraget. - Lund : Studentlitteratur. ; , s. 67-82
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 15. |
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| 16. |
- Hanson, Lars, et al.
(författare)
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Mannequin Properties Desired for Ergonomic Evaluation of Car Interiors
- 1998
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Ingår i: ; , s. 43-48
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Konferensbidrag (refereegranskat)abstract
- Mannequin properties desired for ergonomic evaluation of car interiors Lars Hansson, Kenneth Holmqvist, Simon Sjölander, Giovanni Distante, Guiseppe Andreoni, Nicholas Colford, Tomas Engström, Gert-Åke Hansson, Roland Kadefors, Patric Petersson, Camilla Rigotti, Lena Sperling, Anders Sundin, Per Östman, Roland Akselsson The aim of this study was to simulate a future mannequin with real people in order to find characteristics necessary for ergonomic evaluation of comfort in car interiors. We argue that the mannequin should ideally perform natural movements, collision detection, a biomechanical model, and eyes. Optional improvements to the mannequin involve muscles and a heart. We also discuss the user interface to the mannequin and means to present mannequin data.
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| 17. |
- Hansson, Lars, et al.
(författare)
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Eye and Body Movements Characterized by Synchronized Sampling
- 1998
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An example of a result from a long-term cooperation with Lund University (together with professor Roland Akselsson at the Department of Ergonomics and Aerosol Technology) there some of the authors. (Engström) gained extensive grants (EU-financing and Wallenberg Stifelsen regarding equipment as well as other founding from e.g. the Swedish Work Environment Found). This publication was a result of the just mentioned EU-financing.
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| 18. |
- Hansson, Lars, et al.
(författare)
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Mannequin Properties Desired for Ergonomic Evaluation of Car Interiors
- 1998
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- An example of a result from a long-term cooperation with Lund University (together with professor Roland Akselsson at the Department of Ergonomics and Aerosol Technology) there some of the authors. (Engström) gained extensive grants (EU-financing and Wallenberg Stifelsen regarding equipment as well as other founding from e.g. the Swedish Work Environment Found). This publication has emanated from an EU-financed research project.
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| 19. |
- Holmqvist, Anders, et al.
(författare)
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A Generic PAT Software Interface for On-Line Monitoring and Control of Chromatographic Separation Systems
- 2016
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Ingår i: 26th European Symposium on Computer Aided Process Engineering. - 1570-7946. - 9780444634283 ; 38, s. 811-816
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Konferensbidrag (refereegranskat)abstract
- This contribution presents a novel process analytical technology (PAT) software interface for online monitoring and control of commercial high-pressure liquid chromatography (HPLC) systems. The developed interface is an add-on to chromatography control software and uses industry-standard bidirectional communication protocols to link sensor technologies with the individual HPLC system components in an overall automation framework that facilitates data acquisition, central operation and control of all instruments. The interface is encoded in the Python™ scripting language and supports versatile data transfer to chromatography control software using either OPC (OLE for process control) or COM (component object model) technologies, which are both based on client/server architectures. By these means, the interface utilizes the flexibility of the high-level programming language for formulating optimal control strategies and enables (semantic) interoperability between the chromatography control software and user defined scripts as well as third-party scientific libraries and numerical packages. The advantages and applicability of the developed interface are highlighted through the implementation of a model-based iterative learning control strategy, in order to assure batch-to-batch repeatability, and open-loop optimal controlled elution trajectories on a commercial HPLC separation system. It is, however, noteworthy that the software interface is completely generic and constitutes a novel framework for implementing any PID control schemes as well as sequential optimal experimental design and model predictive control strategies.
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| 20. |
- Holmqvist, Anders, et al.
(författare)
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A model-based methodology for the analysis and design of atomic layer deposition processes-Part III : Constrained multi-objective optimization
- 2013
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 96, s. 71-86
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a structured methodology for the constrained multi-objective optimization (MO) of a continuous cross-flow atomic layer deposition (ALD) reactor model with temporal precursor pulsing. The process model has been elaborated and experimentally validated in the first two papers of this series (33 and 34). A general constrained MO problem (MOP) was formulated to simultaneously optimize quasi-steady-state reactor throughput and overall precursor conversion for the controlled deposition of ZnO films from Zn(C2H5)(2) and H2O, subject to a set of operational constraints. These constraints included lower bounds for the cross-substrate film thickness uniformity and post-precursor purge duration. The non-dominated Pareto optimal solutions obtained successfully revealed the relation between the incommensurable process objectives and reduced the design space of the ALD process into a feasible set of design alternatives. The results presented here show that post-precursor purge duration is essential when optimizing throughput in temporally separated ALD processes, and that this is a major drawback when considering operation at atmospheric pressure. Finally, the robustness of the process along the Pareto optimal front, i.e. the ability of the process to accommodate variations in the associated set of optimal decision variables (DVs), was assessed by Monte Carlo simulations, in which the values of the parametric uncertainties were randomly generated from a multivariate normal distribution. The uncertainty and sensitivity analysis showed that the inherent robustness of the process is progressively lost with the precursor conversion, and revealed the mechanistic dependence of all DVs on the proposed optimization specifications.
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| 21. |
- Holmqvist, Anders, et al.
(författare)
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A model-based methodology for the analysis and design of atomic layer deposition processes—Part I : Mechanistic modelling of continuous flow reactors
- 2012
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 81, s. 260-272
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development of an experimentally validated model that mechanistically comprehends the complex interaction between the gas-phase fluid dynamics, the mass transport of individual species, and the heterogeneous gas–surface reaction mechanism in a continuous cross-flow atomic layer deposition (ALD) reactor. The developed ALD gas–surface reaction mechanism, purely based on consecutive and parallel elementary Eley–Rideal reaction steps, was incorporated into the computational fluid dynamic representation of the equipment-scale. Thereby, the model mechanistically relates local gas-phase conditions in the vicinity of the substrate surface to the transient production and consumption of the fractional surface coverage of chemisorbed species, ultimately underlying epitaxial film growth. The model is oriented towards optimization and control and enables identification of substrate film thickness uniformity sensitivities to process operating parameters, reactor system design and gas flow distribution. For the experimental validation of the derived mathematical model, a detailed experimental investigation with the focus on the impact of process operating parameters on the spatial evolution of ZnO film thickness profile was performed. The controlled deposition of ZnO from Zn(C2H5)2 and H2O was carried out in the continuous cross-flow ALD reactor system F-120 by ASM Microchemistry Ltd. and ex situ film thickness measurements at a discrete set of sampling positions on the substrate were performed using X-ray reflectivity and X-ray fluorescence analysis. The experimental results reported here, underscore the importance of substrate-scale uniformity measurements in developing mechanistic ALD process models with high predictability of the dynamic evolution of the spatially dependent film thickness profile. The experimental validation and extensive mechanistic analysis of the ALD reactor model are presented in the second article of this series.
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| 22. |
- Holmqvist, Anders, et al.
(författare)
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A model-based methodology for the analysis and design of atomic layer deposition processes—Part II : Experimental validation and mechanistic analysis
- 2013
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 94, s. 316-329
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Tidskriftsartikel (refereegranskat)abstract
- This paper demonstrates the experimental validation and mechanistic analysis of the continuous cross-flow atomic layer deposition (ALD) reactor model developed in the first article of this series (Holmqvist et al., in press). A general nonlinear parameter estimation problem was formulated to identify the kinetic parameters involved in the developed ALD gas–surface reaction mechanism, governing ZnO film growth, from ex situ film thickness measurements. The presented methodology for comprehensive model assessment considers the statistical uncertainty of least-squares estimates and its ultimate impact on the model predicted response. Joint inference regions were determined to assess the significance of parameter estimates and results indicate that all estimates involved in the precursor half-reactions were adequately determined. The reparameterization of the Arrhenius equation effectively decreased the characteristically high correlations between Arrhenius parameters, leading to improvement in precision of individual parameter estimates. Model predictions of the spatially dependent film thickness profile with narrow confidence band were in good agreement with both calibration and validation experimental data, respectively, under a wide range of operating conditions. The subsequent extensive theoretical analysis exhibits that the experimentally validated model successfully reproduces the detailed process dynamics revealed by in situ quartz crystal microbalance and quadrupole mass spectroscopy diagnostics, and thereby provides a supplementary analysis tool. Finally, the univariate sensitivity analysis revealed the mechanistic dependence of all the measured process operating parameters on the spatially dependent film thickness profile, resolved at the level of a single pulse sequence. Hence, the presented model-based framework serves as a means to guide future research efforts in the field of ALD process optimization.
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| 23. |
- Holmqvist, Anders, et al.
(författare)
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Dynamic Multi-Objective Optimization of Batch Chromatographic Separation Processes
- 2015
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Ingår i: Computer Aided Chemical Engineering. - 1570-7946. - 9780444634290 ; 37, s. 815-820
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Konferensbidrag (refereegranskat)abstract
- This contribution presents a novel offline dynamic multi-objective optimization framework for high-pressure liquid chromatographic (HPLC) processes in batch elution mode. The framework allows for optimization of general elution trajectories parametrized with piecewise constant control signals. It is based on a simultaneous method where both the control and state variables are fully discretized in the temporal domain, using orthogonal collocations on finite elements, and the state variables are discretized in the spatial domain, using a finite volume weighted essentially non-oscillatory (WENO) scheme. The resulting finite dimensional nonlinear program (NLP) is solved using a primal-dual interior point method and automatic differentiation techniques. The advantages of this open-loop optimal control methodology are highlighted through the solution of a challenging ternary complex mixture separation problem for a hydrophobic interaction chromatography (HIC) system. For a bi-objective optimization of the target component productivity and yield, subject to a purity constraint, the set of Pareto solutions generated with general elution trajectories showed considerable improvement in the productivity objective when compared to the Pareto set obtained using conventional linear elution trajectories.
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| 24. |
- Holmqvist, Anders, et al.
(författare)
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Dynamic parameter estimation of atomic layer deposition kinetics applied to in situ quartz crystal microbalance diagnostics
- 2014
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 111, s. 15-33
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the elaboration of an experimentally validated model of a continuous cross flow atomic layer deposition (ALD) reactor with temporally separated precursor pulsing encoded in the Moclelica language. For the experimental validation of the model, in situ quartz crystal microbalance (QCM) diagnostics was used to yield submonolayer resolution of mass deposition resulting from thin film growth of ZnO from Zn(C-2)(2) and H2O precursors. The ZnO ALD reaction intrinsic kinetic mechanism that was developed accounted for the temporal evolution of the equilibrium fractional surface concentrations of precursor adducts and their transition states for each half reaction, This mechanism was incorporated into a rigorous model of reactor transport, which comprises isothermal compressible equations for the conservation of mass, momentum and gas-phase species. The physically based model in this way relates the local partial pressures of precursors to the dynamic composition of the growth surface, and ultimately governs the accumulated mass trajectory at the QCM sensor. Quantitative rate information can then be extracted by means of dynamic parameter estimation. The continuous operation of the reactor is described by limit-cycle dynamic solutions and numerically computed using Radau collocation schemes and solved using CasADi's interface to [PORT. Model predictions of the transient mass gain per unit area of exposed surface QCM sensor, resolved at a single pulse sequence, were in good agreement with experimental data under a wide range of operating conditions. An important property of the limit-cycle solution procedure is that it enables the systematic approach to analyze the dynamic nature of the growth surface composition as a function of process operating parameters. Especially, the dependency of the film growth rate per limit-cycle on the half-cycle precursor exposure close and the process temperature was thoroughly assessed and the difference between ALD in saturating and in non-saturating film growth conditions distinguished. (c) 2014 Elsevier Ltd. All rights reserved.
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| 25. |
- Holmqvist, Anders, et al.
(författare)
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Methods and Tools for Robust Optimal Control of Batch Chromatographic Separation Processes
- 2015
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Ingår i: Processes. - : MDPI AG. - 2227-9717. ; 3:3, s. 568-606
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Tidskriftsartikel (refereegranskat)abstract
- This contribution concerns the development of generic methods and tools for robust optimal control of high-pressure liquid chromatographic separation processes. The proposed methodology exploits a deterministic robust formulation, that employs a linearization of the uncertainty set, based on Lyapunov differential equations to generate optimal elution trajectories in the presence of uncertainty. Computational tractability is obtained by casting the robust counterpart problem in the framework of bilevel optimal control where the upper level concerns forward simulation of the Lyapunov differential equation, and the nominal open-loop optimal control problem augmented with the robustified target component purity inequality constraint margin is considered in the lower level. The lower-level open-loop optimal control problem, constrained by spatially discretized partial differential equations, is transcribed into a finite dimensional nonlinear program using direct collocation, which is then solved by a primal-dual interior point method. The advantages of the robustification strategy are highlighted through the solution of a challenging ternary complex mixture separation problem for a hydrophobic interaction chromatography system. The study shows that penalizing the changes in the zero-order hold control gives optimal solutions with low sensitivity to uncertainty. A key result is that the robustified general elution trajectories outperformed the conventional linear trajectories both in terms of recovery yield and robustness.
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| 26. |
- Holmqvist, Anders
(författare)
-
Model-based Analysis and Design of Atomic Layer Deposition Processes
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atomic layer deposition (ALD) is a thin-film manufacturing process in which the growth surface is exposed to non-overlapping alternating injections of gas-phase chemical precursor species separated by intermediate purge periods to prevent gas-phase reactions. ALD is characterized by sequential self-terminating heterogeneous reactions between highly reactive gas-phase precursor species and surface-bound species which, when allowed sufficient conditions to reach saturation, results in highly conformal films, on both planar and topographically complex structures. ALD has already emerged as the prime candidate for depositing ultra-thin layers with high conformality in semiconductor manufacturing. With recent advances in current technologies, novel applications of ALD are expanding beyond semiconductor processing in several emerging areas, such as surface passivation layers in crystalline silicon solar cells, buffer layers in CuIn_{1-x}Ga_{x}Se_{2} (CIGS) solar cells, and diffusion barrier layers in organic light-emitting diodes and thin-film photovoltaics. This trend brings with it a growing necessity for high-throughput and low-cost production techniques. This thesis describes the modeling of the ALD process with temporally separated precursor pulsing, which is a special modification of the chemical vapor deposition (CVD) technique, with which it shares a number of phenomenological characteristics. In particular, both deposition processes are inherently nonlinear and time-dependent, and mathematical model components describing the precursor thermophysical properties, the underlying reactor-scale mass transport of the gas-phase precursor and the deposition surface reaction are strongly coupled. Thus, the integration of physical and chemical phenomena over multiple time and length scales is a fundamental requirement for the understanding and modeling of the complete reactor system. However, what distinguishes ALD from CVD is that the steady-state deposition rate in CVD does not exist in ALD. The deposition rate of ALD depends strongly on the dynamic composition of the growth surface and the local precursor partial pressure in the vicinity of the active surface, which both change continuously through each exposure and purge period. The completely dynamic nature of the ALD process adds considerably to the difficulty of developing simulators, as the entire process cycle must be modeled due to the complex interdependence between the sequential ALD half-reactions, such that the reactivity in one half-cycle is influenced by that in the half-cycle preceding it. One of the essential advantages of ALD, on the other hand is that its self-terminating nature enables uniform coating of large-surface-area substrates, thus providing an easier pathway for process scale-up compared to CVD. In the work presented in this thesis, a physically-based dynamic model of the ALD process was developed, based on a laboratory-scale, continuous cross-flow ALD reactor system (F-120 manufactured by ASM Microchemistry Ltd.) equipped with a quartz crystal microbalance for in situ deposition measurements. The mathematical model of the low-volume, continuous cross-flow ALD reactor with temporally separated precursor pulsing comprises components that describe reactor-scale gas-phase dynamics and surface state dynamics to accurately characterize the continuous, cyclic ALD reactor operation that is described by limit-cycle dynamic solutions. The model is coupled to a heterogeneous surface reaction model based on estimated kinetic parameters from ex situ and in situ deposition measurements. The heterogeneous gas--surface reactions mean that there will be a net mass consumption at the growth surface, and the total gas-phase mass flux of species at the growth surface is balanced by the net consumption rate per unit area. Likewise, the accumulated mass resulting from the epitaxial film growth, governed by the adsorption/chemisorption and surface reaction of precursor species, was conveniently expressed in terms of the spatial and temporal evolution of the fractional concentrations of surface states for each half-reaction. In this way, the film growth per cycle (GPC) and its relative uniformity were unambiguously defined. The work described in this thesis was motivated by the predictive capabilities of physically based ALD process models, as such models can be used in the design of novel reactors, the optimization of deposition conditions, and in the scale-up of laboratory thin-film process. The process model, oriented towards optimization and control, was validated experimentally, to ensure that it could adequately predict the spatially dependent film thickness profile and provide statistically reliable least-square estimates of the parameters involved in the heterogeneous gas--surface reaction mechanism that governs the thin film growth of ZnO from Zn(C_{2}H_{5})_{2} and H_{2}O precursors. However, the general formalism of the model allows it to be used to simulate other ALD process chemistries and more complex (e.g., multi-wafer) reactor systems, thereby providing a framework for model-based process design and dynamic optimization studies, as well as controller development. The primary contribution of this work is the solution strategy developed for the dynamic ALD process model, to consider the limit-cycle solutions that describe steady (but periodic) operation of the reactor system, in conjunction with numerical solvers for limit-cycle-constraint, multi-objective optimization, dynamic optimization, and dynamic parameter estimation problems. The utility of the model-based framework developed was demonstrated by a study of constrained multi-objective optimization of the incommensurable process objectives of limit-cycle deposition rate and overall precursor conversion, subject to a set of operational constraints on the uniformity of cross-substrate film thickness and the duration of the post-precursor purge. Additionally, limit-cycle dynamic optimization targeting precursor utilization was also demonstrated in a scale up-analysis of the laboratory-scale reactor, while assuring that identical deposition profiles were obtained in the scaled-up system. In these studies, the optimal solutions obtained revealed the mechanistic dependence of the process operating parameters on the proposed optimization and constraint specifications, and reduced the design space of the ALD process to a feasible set of design alternatives.
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| 27. |
- Holmqvist, Anders, et al.
(författare)
-
Open-loop optimal control of batch chromatographic separation processes using direct collocation
- 2016
-
Ingår i: Journal of Process Control. - : Elsevier BV. - 0959-1524. ; 46, s. 55-74
-
Tidskriftsartikel (refereegranskat)abstract
- This contribution presents a novel model-based methodology for open-loop optimal control of batch high-pressure liquid chromatographic (HPLC) separation processes. The framework allows for simultaneous optimization of target component recovery yield and production rate with respect to a parameterization of the input elution trajectory and fractionating interval endpoints. The proposed methodology implies formulating and solving a large-scale dynamic optimization problem (DOP) constrained by partial differential equations (PDEs) governing the multi-component system dynamics. It is based on a simultaneous method where both the control and state variables are fully discretized in the temporal domain, using direct local collocation on finite elements, and the state variables are discretized in the spatial domain, using an adaptive finite volume weighted essentially non-oscillatory (WENO) scheme. The direct transcription of the DOP described by Modelica, and its extension Optimica, code into a sparse nonlinear programming problem (NLP) is thoroughly presented. The NLP was subsequently solved using CasADi's (Computer algebra system with Automatic Differentiation) interface to the primal-dual interior point method IPOPT. The advantages of the open-loop optimal control strategy are highlighted through the solution of a challenging ternary complex mixture separation problem of human insulin analogs, with the intermediately eluting component as the target, for a hydrophobic interaction chromatography system. Moreover, the high intercorrelation between the shape of the optimal elution trajectories and the fractionation interval endpoints is thoroughly investigated. It is also demonstrated that the direct transcription methodology enabled accurate and efficient computation of optimal cyclic-steady-state solutions, which govern that state and control variables conform to periodicity constraints imposed on column re-generation and re-equilibration. By these means, the generic methods and tools developed here are applicable to continuous chromatographic separation technologies, including the continuous simulated moving bed (SMB) and the multicolumn counter-current solvent gradient purification (MCSGP) process.
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| 28. |
- Holmqvist, Anders, et al.
(författare)
-
Scale-up Analysis of Continuous Cross-flow Atomic Layer Deposition Reactor Designs
- 2014
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 117, s. 301-317
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the development of a non-dimensional model of a continuous cross-flow atomic layer deposition (ALD) reactor with temporally separated precursor pulsing and a structured model-based methodology for scaling up the substrate dimensions. The model incorporates an ALD gas–surface reaction kinetic mechanism for the deposition of thin ZnO films from Zn(C2H5)2 and H2O precursors that was experimentally validated in our previous work (Holmqvist et al., 2012, 2013a). In order to maintain dynamic similarity, a scaling analysis was applied based on the dimensionless numbers, appearing in non-dimensionalized momentum and species mass conservation equations, that describe the convective laminar flow, mass transfer and heterogeneous reaction. The impact on these dimensionless numbers and, more importantly, the impact on the limit-cycle deposition rate and its relative uniformity was thoroughly investigated when linearly scaling up the substrate dimensions. In the scale-up procedure, the limit-cycle precursor utilization was maximized by means of dynamic optimization, while ensuring that identical deposition profiles were obtained in the scaled-up system. The results presented here demonstrated that the maximum precursor yields were promoted at higher substrate dimensions. Limit-cycle dynamic solutions to the non-dimensionalized model, computed with a collocation discretization in time, revealed that it is a combination of the degree of precursor depletion in the flow direction and the magnitude of the pressure drop across the reactor chamber that governs the extent of the deposition profile non-uniformity. A key finding of this study is the identification of optimal scaling rules for maximizing precursor utilization in the scaled-up system while maintaining fixed absolute growth rate and its relative uniformity.
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| 29. |
- Holmqvist, Anders, et al.
(författare)
-
The Lycksele ring structure–still no proof of an impact origin
- 2020
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Ingår i: GFF. - : Taylor & Francis. - 1103-5897 .- 2000-0863. ; 142:2, s. 96-99
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Tidskriftsartikel (refereegranskat)abstract
- The origin of the more than 100 km wide Lycksele ring structure in Sweden has puzzled geoscientists for years. In this short note we present results from field analysis, detailed sampling and laboratory analysis executed in search for evidence of an impact, e.g. shatter cones and shock features in minerals. Both approaches gave negative results and consequently an impact origin could neither be confirmed nor rejected. The circular structure of the Lycksele ring and its central uplift are, however, typical features of large, complex impact structures.
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| 30. |
- Holmqvist, Anders, et al.
(författare)
-
Ultrafiltration of kraft black liquor from two Swedish pulp mills
- 2005
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Ingår i: Chemical Engineering Research & Design. - : Elsevier BV. - 0263-8762. ; 83:A8, s. 994-999
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Tidskriftsartikel (refereegranskat)abstract
- Extraction of lignin by ultrafiltration of black liquor from two Swedish pulp mills has been studied. One of the mills employs batch digestion and the other continuous digestion. At both mills softwood was used as raw material. The black liquor was withdrawn before the evaporator unit. A ceramic membrane with a cut-off of 15 000 g mol(-1) was used in the experiments. The average flux during concentration to 90% volume reduction was 160 and 110L m(-2) h(-1) for the liquors from the batch and the continuous digestion processes, respectively, when the temperature was 90 degrees C and the transmembrane pressure 200 kPa. The retention of lignin was about the same for both liquors, 35%. A cost estimate of extraction of lignin fuel from black liquor was made, based on experimental data from ultrafiltration at various operating conditions. The cost was found to be about 20 E per MWh of calorific value of the lignin fuel.
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| 31. |
- Holmqvist, Claes, et al.
(författare)
-
A flexible approach for modelling flow in multi-component blade formers
- 2006
-
Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 21:1, s. 73-81
-
Tidskriftsartikel (refereegranskat)abstract
- The internal structure of the fibre network constituting a paper is to a dominating extent determined in the forming zone of the paper machine. In this article we present a method for modelling the pressure distributions in blade forming sections, which is commonly considered to be a key quantity of the process. The ambition is to obtain a tool by which the interaction between the different components of blade sections can be studied. It is achieved by defining modules out of which arbitrary sections can be constructed. The modules are solved independently and matched to each other iteratively Keeping the interface between the modules simple provides great flexibility in the modelling. By virtue of a slenderness assumption, the equations governing each module can be reduced to one-dimensional form, hence limiting the computational work and permitting systems of many components to be studied. Dimensionless numbers defining the problem are identified, and the magnitude of the nonlinear effects are estimated. Simulations are presented that illustrate the potential of the method.
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| 32. |
- Holmqvist, Claes, et al.
(författare)
-
Consolidation of sheared, strongly flocculated suspensions
- 2008
-
Ingår i: AIChE Journal. - : Wiley. - 0001-1541 .- 1547-5905. ; 54:4, s. 924-939
-
Tidskriftsartikel (refereegranskat)abstract
- The concept of a particle concentration dependent yield stress, previously employed in studies of uniaxial consolidation of a flocculated solid phase dispersed in a liquid, is extended to comprise flocculated phase shear strength. The inter-particle stresses are modeled by assuming that the stress state is always located on a yield-surface in stress-space, whose form is adopted from the Cam-clay plasticity theory for the quasistatic consolidation of soil. By treating the time-dependent dewatering of a suspension trapped between a permeable filter and a sliding piston, as well as the asymptotic limit of a cross-flow filtration situation, the differences with respect to the conventional uniaxial models are made apparent, and the effects of the shear stresses on the consolidation process are elucidated. Applying shear is predicted to increase the rate of the drainage process, because of a reduced load bearing capacity of the flocculated phase, and the correspondingly higher pore pressures.
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| 33. |
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| 34. |
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| 35. |
- Holmqvist, Claes, 1973-
(författare)
-
Mechanical modelling of blade forming and drainage of flocculated suspensions
- 2005
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A method has been developed for flexible modelling of multi-component twin-wire blade formers. Features such as suction devices, loadable blades, curved blades, and partial contact between the blades and the forming fabrics are easily incorporated. New results include a series of calculations demonstrating the non-trivial interaction between the pressure pulses when the blades are positioned successively closer together, the effects of suction on the pressure pulse generated by a blade applied to the opposing wire, and how blades of modest curvature do not necessarily stay in contact with the fabric along their full width and the implications of this on the pressure gradients in the machine direction. The behaviour of the fibre mats as they experience the first of the blade pulses (after having been formed over a roll) is then considered in detail. Typically, the thickness of the mats decreases during the pulse, which reduces the rate of deposition of new fibres onto the webs. The amount of fibres in the sheets therefore changes marginally. Nevertheless, the resistance to drainage presented by the fibre network is seen to increase significantly due to the low permeability in highly compressed layers of the mat. As a result of the pressure gradients in the machine direction, the shear stresses in the plane of the fibre sheets can attain several hundred Pascal next to the forming fabrics. Further, a model for sheared consolidation of flocculated suspensions is presented that extends the concept of a concentration dependent yield stress, previously employed in studies of uniaxial consolidation, to comprise flocculated phase shear strength. Rate-dependent viscous stresses are also incorporated. The theory is applied to the problem of combined compression and shearing of a strongly flocculated suspension contained between two plates, one being fixed and acting as a perfectly permeable filter, the other movable and acting as a piston by which the load is applied. Qualitatively, the evolution of the volume fraction of solids exhibits the same behaviour as during uniaxial consolidation without shear. Applying shear is however predicted to increase the rate of the drainage process, due to a reduced load bearing capacity of the flocculated phase, and correspondingly higher pore pressures.
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| 36. |
- Holmqvist, Fredrik, et al.
(författare)
-
Atrial fibrillation signal organization predicts sinus rhythm maintenance in patients undergoing cardioversion of atrial fibrillation.
- 2006
-
Ingår i: Europace. - : Oxford University Press (OUP). - 1532-2092. ; 8:8, s. 559-565
-
Tidskriftsartikel (refereegranskat)abstract
- Electrical remodelling is believed to influence the outcome following cardioversion of patients with persistent atrial fibrillation (AF). However, the results in clinical studies are conflicting. We assessed the hypothesis that non-invasively obtained atrial fibrillatory organization can be used as a predictor of sinus rhythm (SR) maintenance. METHODS AND RESULTS: Fifty-four patients (37 men, age 67+/-11) with persistent AF (median duration 3 months, 1 day to 18 months), without anti-arrhythmic drug treatment, referred for cardioversion were studied. Assessment of the atrial harmonic decay was made by time-frequency analysis of the ECG. At 1-month follow-up, 30 patients had relapsed into AF. The mean harmonic decay at inclusion of those relapsing into AF was 1.5+/-0.3 compared with 1.1+/-0.3 among those maintaining SR (P=0.0004). Using a cut-off value of harmonic decay
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| 37. |
- Holmqvist, Fredrik, et al.
(författare)
-
Indices of electrical and contractile remodeling during atrial fibrillation in man
- 2006
-
Ingår i: PACE. - : Wiley. - 1540-8159. ; 29:5, s. 512-519
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Tidskriftsartikel (refereegranskat)abstract
- Atrial electrical and contractile remodeling have been demonstrated to coincide during atrial fibrillation (AF) in experimental studies. We explored whether electrical and contractile remodeling correlate in man and explored its clinical implications. METHODS: Forty-nine patients with persistent AF were studied. Electrical remodeling was assessed noninvasively using spectral analysis to estimate the average fibrillatory rate (AFR). Atrial contractility was assessed by transesophageal echocardiography (TEE) measurement of left atrial appendage outflow velocity (LAAOV). RESULTS: The AFR was 403+/-43 fibrillations per minute (fpm) and the LAAOV was 0.27+/-0.14 m/s. A significant correlation was found between AFR and LAAOV (r=-0.47, P=0.001). In patients with a LAAOV>or=0.25 m/s, the AFR was 387+/-48 fpm compared to 419+/-31 fpm among patients with LAAOV<0.25 m/s (P<0.01). CONCLUSIONS: This study demonstrates that indices of electrical and contractile remodeling are strongly correlated in persistent AF in man. The interindividual overlap, however, is too large to allow predictions of LAAOV based on fibrillatory frequency alone.
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| 38. |
- Holmqvist, Fredrik, et al.
(författare)
-
Rapid fluctuations in atrial fibrillatory electrophysiology detected during controlled respiration.
- 2005
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Ingår i: American Journal of Physiology: Heart and Circulatory Physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 289:2, s. 754-760
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Tidskriftsartikel (refereegranskat)abstract
- Heart rate during sinus rhythm is modulated through the autonomic nervous system, which generates short-term oscillations. The high-frequency components in these oscillations are associated with respiration, causing sinus arrhythmia, mediated by the parasympathetic nervous system. In this study, we evaluated whether slow, controlled respiration causes cyclic fluctuations in the frequency of the fibrillating atria. Eight patients (four women; median age 63 yr, range 53–68 yr) with chronic atrial fibrillation (AF) and third-degree atrioventricular block treated by permanent pacemaker were studied. ECG was recorded during baseline rest, during 0.125-Hz frequency controlled respiration, and finally during controlled respiration after full vagal blockade. We calculated fibrillatory frequency using frequency analysis of the fibrillatory ECG for overlapping 2.5-s segments; spectral analysis of the resulting frequency trend was performed to determine the spectrum of variations of fibrillatory frequency. Normalized spectral power at respiration frequency increased significantly during controlled respiration from 1.4 (0.76–2.0) (median and range) at baseline to 2.7 (1.2–5.8) ( P = 0.01). After vagal blockade, the power at respiration frequency decreased to 1.2 (0.23–2.8) ( P = 0.01). Controlled respiration causes cyclic fluctuations in the AF frequency in patients with long-duration AF. This phenomenon seems to be related to parasympathetic modulations of the AF refractory period.
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| 39. |
- Holmqvist, Marika, 1959-, et al.
(författare)
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Asking patients about their drinking - A national survey among primary health care physicians and nurses in Sweden
- 2008
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Ingår i: Addictive Behaviors. - : Elsevier BV. - 0306-4603. ; 33:2, s. 301-314
-
Tidskriftsartikel (refereegranskat)abstract
- Aims To investigate the extent to which Swedish primary health care (PHC) general practitioners (GPs) and nurses discuss alcohol issues with their patients, their reasons for and against addressing alcohol issues, their perceived importance of these issues, and factors that could facilitate increased alcohol intervention activity among the PHC professionals. Methods All Swedish GPs and nurses who have the authority to issue prescriptions were surveyed with a postal questionnaire. The questionnaire was returned by 1821 GPs (47% response rate) and 3125 nurses (55% response rate). Results Fifty percent of the GPs and 28% of the nurses stated that they “frequently” discussed alcohol with their patients. The two most common reasons for asking patients about their drinking were that the GPs and nurses considered it part of their routines and the belief that the patient had alcohol-related symptoms. GPs said that improved opportunities for referral to specialists and provision of more knowledge about counselling techniques for use when alcohol-related symptoms are evident were the most important facilitators to increased intervention activity. Concerning the nurses, 93% stated that more time devoted to health-oriented work could facilitate increased alcohol intervention activity. Conclusions The findings highlight a considerable gap between the recognition of the significance of the alcohol problem and Swedish PHC intervention activity. Keywords: Primary health care; Alcohol intervention; Risk consumption
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| 40. |
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| 41. |
- Holmqvist, Magnus, et al.
(författare)
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E-business and spare part distribution
- 2003
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Ingår i: In the Proceedings of the Logistics Research Network 2003 Annual Conference (LRN), London, England, 11-12 September 2003..
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 42. |
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| 43. |
- Holsanova, Jana, et al.
(författare)
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Visualisering av ögonrörelser som stöd för motivation, metakognition och lärande
- 2014
-
Ingår i: Vetenskapliga perspektiv på lärande, undervisning och utbildning i olika institutionella sammanhang : utbildningsvetenskaplig forskning vid Lunds universitet. - 9789174738629 ; , s. 369-380
-
Bokkapitel (refereegranskat)abstract
- Bidraget presenterar ett nytt pedagogiskt verktyg (EyeLearn) som baseras på ögonrörelsemätningsmetoden och används som stöd för motivation, metakognition och lärande. Genom visualiseringar av ögonrörelser kan man följa problemlösningsprocessen, ge stöd till lågpresterande elever, förbättra elevers metakognitiva förmågor och studieteknik, plocka fram exempel på framgångsrika och mindre framgångsrika strategier, motivera elever genom att engagera dem i jämförande diskussioner om alternativa lösningar samt anpassa digitala läromedel efter elevernas förmåga och preferens. Verktyget stödjer därmed interaktivitet, ger återkoppling till eleven, respekterar individernas lärstilar, erbjuder former av samarbete och stödjer metakognition.
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| 44. |
- Håkansson, Anders, et al.
(författare)
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Cross-Fertilization of Courses to Improve Student Learning
- 2016
-
Ingår i: Proceedings of the 18th International Conference on Engineering and Product Design Education. - Glasgow : The Design Society. - 9781904670780 ; , s. 626-631
-
Konferensbidrag (refereegranskat)abstract
- Teaching is an area that should be in a constant ongoing development or should at least be a processquestioned and revised according to the fact that the society, the students and new knowledge aboutteaching methods are not static. Whether teaching needs to change in terms of how it can enhancestudent learning opportunities must always be subject to an ongoing process. This article describes thisneed and how changes are made to improve students learning in one of the courses in the IndustrialDesign engineering program. The set up in a program like this is a compromise between two differentprofessions as in this case between mechanical engineers and industrial designers. This is a challengethat is tainted with some problems. One of these problems is to accommodate both professions in thesame application. These compromises are never optimal solutions and this have the result that somesubjects have to disappear or be minimized from each profession. Traditionally design trainingprograms contains more of hands on education than machine engineering programs and students inindustrial Design programs are also expected to have some basic knowledge already when applyingwhen applying to their educational program. Some examples of hands on courses as Model makingand sketching cannot be studied only as theory, skills in this case needs training and also timeprovided to allow the knowledge to mature. This article describes an attempt to improve this twoprofession trade-off and how to improve learning in both practical skills and theoretical skills by anew course design. The article also shows how this example could be of interest for other programsand other courses.
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| 45. |
- Håkansson, Anders, et al.
(författare)
-
Managing multidisciplinarity : growing future creators
- 2013
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Ingår i: Design Education - Growing our Future. - Glasgow : Design Research Society. - 9781904670421 ; , s. 587-592
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Konferensbidrag (refereegranskat)abstract
- Preparing students for real life is a main issue for education programs. At Luleå University of Technology, (LTU), this is done by a range of different course layouts and course assignments. Students studying at the Industrial Design Engineering program practice this as group work, workshops and individual assignments always based on the intention to be as close to what students will face after exam in their first employments. Yet there is a major problem with this. Assignments are still not sharp and students know the worst outcome would be to not pass. This paper describes a project assignment connected to an international competition and on a complexity level that needs competences from several different university programs. The project is a competition, which is a successful way to increase focus, commitment and reaching a higher level of result. In this project students have to form their own project organization, plan and distribute work. This is very close to how they are going to act in their future profession and how they have to interact with other professions in the real life situation. Interaction with other programs sometimes occurs but in this project the interaction is on a much higher level because of the complexity and the intensity that is the effect of a competition. Being a part of a bigger project organization gives experiences in collaborating as handling personal problems and people acting unexpected with other competences. Successful competitions results create attention good for students, teachers and the university.
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| 46. |
- Håkansson, Anders, et al.
(författare)
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Stimulate student business outcome through needfinding-oriented projects
- 2011
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Ingår i: Design education for creativity and business innovation. - Glasgow : Design Research Society. - 9781904670339 ; , s. 391-396
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Konferensbidrag (refereegranskat)abstract
- At the department of Human Work Sciences at Luleå University of Technology, LTU, there is a long tradition of working in student driven product development projects in cooperation with companies in the industry. The main structure of these projects is to develop assignments together with the companies and let the students address these problems during the projects. This leads to stimulating and real tasks where the students are very committed. However, the tasks are relatively well defined and are more like consultant assignments where the students act like the consultants and work directly with the companies’ problems. The ambition was to increase the element of innovation and entrepreneurship and through that increase the ambition and conditions for starting new companies. To achieve this, need finding methodology based on Patnaik and Becker was introduced in order to give the students a tool to work with more loosely defined tasks. The projects where not defined more than as a few different scenarios where the students were requested to identify needs and from that develop a product or service to satisfy these needs. From the need finding, the use of scenarios and personas the outcome was a number of unique and innovative solutions. The students experienced the new approach as scary at first but gradually started to appreciate it as long as the project proceeded. The course assessment showed that the new way of addressing problems when developing products filled a gap in the methodology package for the students. However, even though the outcome showed a successful result regarding innovativeness the projects ended without being implemented as products on the market. This step seemed to be too much to overcome. According to that an additional aspect was introduced the third time the course was given. From the start the projects were carried out without cooperation with the industry in any way but this time a company committing them selves to buy and produce the best solution was involved. The company introduced in the course provides gifts and profile products to other companies and organizations. This means they have a great number of different products in their collection. The student project groups task was to find and create a new suitable product to offer them. The class of students was divided into groups of four and they all worked with the same assignment in competition with each other. The outcome of this project was a great number of different solutions depending on which target group the students had chosen to focus on and which needs were identified. The result from, the need finding were, in the cases when it was an advantage, prototyped in the rapid prototyping equipment which is a way to make models of high quality close to production ready designs. In the end, several solutions were chosen for production by the company. All in all, this approach turned out to greatly stimulate an entrepreneurial approach and further develop the students’ ability for innovative thinking. The use of need finding-based projects in a strong competitive situation is useful for the students. To focus more towards entrepreneurship and innovation proved to stimulate start-up of new companies and it can also show the students that a self-employed future is realistic.
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| 47. |
- Håkansson, Anders, et al.
(författare)
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University-industry cooperation and student driven projects : a model for educating design engineers
- 2010
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Ingår i: When Design Education and Design Research Meet. - Glasgow : Design Research Society. - 9781904670193 ; , s. 414-419
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Konferensbidrag (refereegranskat)abstract
- Cooperating with industry to create "real life" projects for students is a 30 year old tradition at the Department of Human Work Sciences at Luleå University of Technology (LTU). This paper describes the approach to university-industry projects at LTU, illustrates benefits and problems in the interaction between students, industry and the university. The students´ practice their abilities in product design and project management. This is also a confirmation of the demand for their education in the industry. By being able to practice their future profession strengthens the student's confidence and gives them a feeling of being competent. During the project the students are given good opportunities to start building their professional network. The projects also act as key features in their CVs and portfolios. These projects serve as a display window for the MSc program Industrial Design Engineering at the Department of Human Work Sciences when recruiting new students as well as for marketing the design engineers to the industry. When employed in the industry, design engineers from LTU often hold key positions where they are excellent contacts for establishing new collaboration. Often these former students contact the university with proposals for cooperation. During the years, many student projects have developed into collaborative research projects. In this way we have created a self generating mechanism where new collaboration is created with former students who themselves have worked in these kinds of projects during their own education. A win-win-win situation is created where university, industry and students all benefit from this.
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| 48. |
- Jankovskaja, Skaidre, et al.
(författare)
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Visualisation of H2O2 penetration through skin indicates importance to develop pathway-specific epidermal sensing
- 2020
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Ingår i: Microchimica Acta. - : Springer. - 0026-3672 .- 1436-5073. ; 187:12
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Tidskriftsartikel (refereegranskat)abstract
- Elevated amounts of reactive oxygen species (ROS) including hydrogen peroxide (H2O2) are observed in the epidermis in different skin disorders. Thus, epidermal sensing of H2O2 should be useful to monitor the progression of skin pathologies. We have evaluated epidermal sensing of H2O2 in vitro, by visualising H2O2 permeation through the skin. Skin membranes were mounted in Franz cells, and a suspension of Prussian white microparticles was deposited on the stratum corneum face of the skin. Upon H2O2 permeation, Prussian white was oxidised to Prussian blue, resulting in a pattern of blue dots. Comparison of skin surface images with the dot patterns revealed that about 74% of the blue dots were associated with hair shafts. The degree of the Prussian white to Prussian blue conversion strongly correlated with the reciprocal resistance of the skin membranes. Together, the results demonstrate that hair follicles are the major pathways of H2O2 transdermal penetration. The study recommends that the development of H2O2 monitoring on skin should aim for pathway-specific epidermal sensing, allowing micrometre resolution to detect and quantify this ROS biomarker at hair follicles. Graphical abstract
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| 49. |
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| 50. |
- Kilbrink, Nina, 1974-
(författare)
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Legorobotar i skolan : Elevers uppfattningar av lärandeobjekt och problemlösningsstrategier
- 2008
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study concerns pupils’ experiences of learning and working with programmable robotics at school. Consequently, the study refers to the use of computers at school and can therefore be placed in the research area of computer aided learning. The aim is to analyze and describe pupils’ different experiences of what they learn by means of working with programmable robotics at school and how they experience that they work and solve problems by means of programming and constructing robotics. The first question concerns the experienced object of learning and the second question is about the experienced problem solving strategies. The theoretical framework and method is in the area of phenomenology of the life-world and phenomenography. The pupils who have been interviewed in the study have all been working with a programmable Lego material and the result is the qualitatively different categories of pupils’ experiences of objects of learning and problem solving strategies in relation to this material. Many experiences focus on social aspects of this work, which means that the technological material itself is not the evident object of learning in the pupils’ experiences. Also the experiences related to the problem solving strategies often focus on a social dimension. The findings should be seen as a contribution to the discussion about understanding pupils’ different ways of experiencing their work and learning in technological surroundings and thereby facilitate the creation of an educational environment where pupils can be met at their level and where teachers can create possibilities for holistic learning. This understanding can contribute to evolve the didactics about computers and technology education.
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