| 1. |
- Amin, Leila, et al.
(författare)
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Swedish national population-based study shows an increased risk of depression among patients with Hirschsprung disease.
- 2019
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Ingår i: Acta Paediatrica. - : Wiley. - 0803-5253 .- 1651-2227. ; 108:10, s. 1867-1870
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Tidskriftsartikel (refereegranskat)abstract
- AIM: Hirschsprung disease is usually treated during infancy. The long-term impact on mental health has not been well studied. The aim of this study was to assess the risk for depressive disorders in individuals with Hirschsprung disease.METHODS: This was a nationwide, population-based cohort study. The study exposure was Hirschsprung disease and the study outcome was depression. The exposed cohort included all individuals with Hirschsprung disease, registered in the Swedish National Patient Register between 1964 and 2013 and the unexposed cohort included ten age- and sex-matched controls per patient. The diagnosis of depression was confirmed by diagnosis in the Swedish National Patient Register.RESULTS: The cohort included 739 (76.5% males) individuals with Hirschsprung disease and 7390 (76.5% males) controls. Among the patients with Hirschsprung disease, 35 (4.7%) of the patients had had a depressive disorder and 187 (2.5%) of controls, hazard ratio 1.98, 95% confidence interval 1.38-2.84. The mean age at diagnosis of first depression was 21.9 years (SD ± 7) in Hirschsprung disease patients and 23.4 years (SD ± 7), p = 0.236 in the unexposed group. There were no significant gender differences.CONCLUSION: We found an increased risk of having depressive disorders among individuals with Hirschsprung disease compared to controls.
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| 2. |
- Andersson, Tomas, et al.
(författare)
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A COVQ-Based image coder for channels with bit errors and erasures
- 2008
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Ingår i: IEEE Transactions on Communications. - : IEEE Communications Society. - 0090-6778 .- 1558-0857. ; 56:2, s. 161-165
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Tidskriftsartikel (refereegranskat)abstract
- We illustrate how channel optimized vector quantization (COVQ) can be used for channels with both bit-errors and bit-erasures. First, a memoryless channel model is presented, and the performance of COVQ's trained for this channel is evaluated for an i.i.d. Gaussian source. Then, the new method is applied in implementing an error-robust sub-band image coder, and we present image results that illustrate the resulting performance. Our experiments show that the new approach is able to outperform a traditional scheme based on separate source and channel coding.
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| 3. |
- Andersson, Tomas, et al.
(författare)
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Design of n-channel multiple description vector quantizers
- 2005
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Ingår i: 2005 39th Asilomar Conference on Signals, Systems and Computers. - NEW YORK : IEEE. ; , s. 13-17
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Konferensbidrag (refereegranskat)abstract
- A new design approach for multiple description vector quantizers over more than two channels is presented. The design is inspired by the concept of channel optimized vector quantization. While most previous works have split the decoder into several independent entities, identifying the appropriate channel model makes it straightforward to implement the multiple description design problem using only one decoder. Our simulation results compare systems with 2, 4 and 8 channels. We demonstrate significant gains over previous designs, as well as over a benchmark scheme based on separate quantization and forward erasure-correcting error control.
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| 4. |
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| 5. |
- Andersson, Tomas, et al.
(författare)
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Frequency estimation utilizing the Hadamard transform
- 2001
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Ingår i: 2001 IEEE WORKSHOP ON STATISTICAL SIGNAL PROCESSING PROCEEDINGS. - NEW YORK : IEEE. - 0780370112 ; , s. 409-412
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Konferensbidrag (refereegranskat)abstract
- Fast analog to digital conversion with only one bit per sample does not only make high sampling rates possible but also reduces the required hardware complexity. For short data buffers or block lengths, it has been shown that tone frequency estimators can be implemented by a simple table look-up. In this paper we present an analysis of such tables using the Hadamard transform. As an outcome of the analysis, we propose a class of nonlinear estimators of low complexity. Their performance is evaluated using numerical simulations. Comparisons are made with the proper Cramer-Rao bound and with the table look-up approach.
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| 6. |
- Andersson, Tomas, et al.
(författare)
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Multiple description image coding based on multi-stage vector quantization
- 2007
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Ingår i: CONFERENCE RECORD OF THE FORTY-FIRST ASILOMAR CONFERENCE ON SIGNALS, SYSTEMS & COMPUTERS. - NEW YORK : IEEE. ; , s. 243-246
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Konferensbidrag (refereegranskat)abstract
- A new design approach for multiple description coding, based on multi-stage vector quantizers, is presented. The design is not limited to systems with two descriptions, but is also well suited for the n-descriptions case. Inspired by the concept of channel optimized vector quantization, the design can easily be tailored to suit different erasure channels, e.g. packet erasure channels with memory (burst-losses). The optimization procedure used in the design takes a sample-iterative approach. All stage codebooks; are updated simultaneously for each vector in the training database. The resulting algorithm has the behaviour of a simulated annealing algorithm, with several good properties, e.g. it usually provides codebooks with good index assignments. Image results are presented for systems with 2 and 4 channels. The image coder is based on a subband transform followed by 64-dimensional vector quantization, to illustrate the capacity of the design to handle large problem sizes.
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| 7. |
- Andersson, Tomas, 1978-
(författare)
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On error-robust source coding with image coding applications
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis treats the problem of source coding in situations where the encoded data is subject to errors. The typical scenario is a communication system, where source data such as speech or images should be transmitted from one point to another. A problem is that most communication systems introduce some sort of error in the transmission. A wireless communication link is prone to introduce individual bit errors, while in a packet based network, such as the Internet, packet losses are the main source of error. The traditional approach to this problem is to add error correcting codes on top of the encoded source data, or to employ some scheme for retransmission of lost or corrupted data. The source coding problem is then treated under the assumption that all data that is transmitted from the source encoder reaches the source decoder on the receiving end without any errors. This thesis takes another approach to the problem and treats source and channel coding jointly under the assumption that there is some knowledge about the channel that will be used for transmission. Such joint source--channel coding schemes have potential benefits over the traditional separated approach. More specifically, joint source--channel coding can typically achieve better performance using shorter codes than the separated approach. This is useful in scenarios with constraints on the delay of the system. Two different flavors of joint source--channel coding are treated in this thesis; multiple description coding and channel optimized vector quantization. Channel optimized vector quantization is a technique to directly incorporate knowledge about the channel into the source coder. This thesis contributes to the field by using channel optimized vector quantization in a couple of new scenarios. Multiple description coding is the concept of encoding a source using several different descriptions in order to provide robustness in systems with losses in the transmission. One contribution of this thesis is an improvement to an existing multiple description coding scheme and another contribution is to put multiple description coding in the context of channel optimized vector quantization. The thesis also presents a simple image coder which is used to evaluate some of the results on channel optimized vector quantization.
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| 8. |
- Appelgren, Patrik, et al.
(författare)
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Disruption mechanisms in electrified solid copper jets
- 2011
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Ingår i: Journal of applied mechanics. - : ASME International. - 0021-8936 .- 1528-9036. ; 78:2
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Tidskriftsartikel (refereegranskat)abstract
- Interaction between a solid copper jet and an electric current pulse is a complex process that has been experimentally studied by letting a jet created by a shaped charge device pass through an electrode configuration consisting of two aluminum plates with a separation distance of 150 mm. When the jet bridged the electrodes, which are connected to a charged pulsed power supply, current pulses with amplitude up to 250 kA were passed through the jet. By using flash X-ray diagnostics, the disruption of the electrified jets could be studied. In this paper, the disruption of the electrified jets is discussed and compared with disruption phenomena observed in electrically exploded metal rods in a static setup. Necks are naturally formed along a stretching jet, and in the experiments with current interaction these necks explode electrically. In the static experiments, the metal rods have small notches distributed along the rod to resemble the necks of the jet. When two neighboring necks or notches explode, the shock of the explosion compresses the intermediate jet or rod segment axially and the material is forced out radially. The disruption phenomena in the jet and rod experiments are similar with rapid expansion of the metal at explosion and at comparable velocities.
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| 9. |
- Appelgren, Patrik, et al.
(författare)
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Experimental Study of Electromagnetic Effects on Solid Copper Jets
- 2010
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Ingår i: Journal of applied mechanics. - : ASME International. - 0021-8936 .- 1528-9036. ; 77:1, s. 011010-
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a study of the interaction between all electric current pulse and a solid copper jet. Experiments were performed using a dedicated pulsed power supply delivering a current pulse of such amplitude, rise little, and duration that the jet is efficiently affected. The copper jet was created by using a shaped charge warhead. All electrode configuration consisting of two aluminum plates with a separation distance of 150 mm was used. The discharge current pulse and the voltages at the capacitors and at the electrodes were measured to obtain data oil energy deposition in and the resistance of the jet and electrode contact region. X-ray diagnostics were used to radiograph the jet, and by analyzing the radiograph, the degree of disruption of the electrified jet could be obtained. It was found that a current pulse with an amplitude of 200-250 kA and a rise time of 16 mu s could strongly enhance the natural fragmentation of the jet. In this case, the initial electric energy was 100 kJ and about 90% of the electric energy was deposited in the jet and electrodes. At the exit of the electrode region, the jet fragments formed rings with a radial velocity of up to 200 m/s, depending oil the initial electric energy in the pulsed power supply. [DOI: 10.1115/1.3172251]
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| 10. |
- Appelgren, Patrik, et al.
(författare)
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Interaction between solid copper jets and powerful electrical current pulses
- 2011
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Ingår i: Journal of applied mechanics. - : ASME International. - 0021-8936 .- 1528-9036. ; 78:2
-
Tidskriftsartikel (refereegranskat)abstract
- The interaction between a solid copper jet and an electric current pulse is studied. Copper jets that were created by a shaped-charge device were passed through an electrode configuration consisting of two aluminum plates with a separation distance of 150 mm. The electrodes were connected to a pulsed-power supply delivering a current pulse with amplitudes up to 250 kA. The current and voltages were measured, providing data on energy deposition in the jet and electrode contact region, and flash X-ray diagnostics were used to depict the jet during and after electrification. The shape of, and the velocity distributions along, the jet has been used to estimate the correlation between the jet mass flow through the electrodes and the electrical energy deposition. On average, 2.8 kJ/g was deposited in the jet and electrode region, which is sufficient to bring the jet up to the boiling point. A model based on the assumption of a homogenous current flow through the jet between the electrodes underestimates the energy deposition and the jet resistance by a factor 5 compared with the experiments, indicating a more complex current flow through the jet. The experimental results indicate the following mechanism for the enhancement of jet breakup. When electrified, the natural-formed necks in the jet are subjected to a higher current density compared with other parts of the jet. The higher current density results in a stronger heating and a stronger magnetic pinch force. Eventually, the jet material in the neck is evaporated and explodes electrically, resulting in a radial ejection of vaporized jet material.
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| 11. |
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| 12. |
- Bergström, Göran, 1964, et al.
(författare)
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Body weight at age 20 and in midlife is more important than weight gain for coronary atherosclerosis: Results from SCAPIS.
- 2023
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Ingår i: Atherosclerosis. - : Elsevier BV. - 1879-1484 .- 0021-9150. ; 373, s. 46-54
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Tidskriftsartikel (refereegranskat)abstract
- Elevated body weight in adolescence is associated with early cardiovascular disease, but whether this association is traceable to weight in early adulthood, weight in midlife or to weight gain is not known. The aim of this study is to assess the risk of midlife coronary atherosclerosis being associated with body weight at age 20, body weight in midlife and body weight change.We used data from 25,181 participants with no previous myocardial infarction or cardiac procedure in the Swedish CArdioPulmonary bioImage Study (SCAPIS, mean age 57 years, 51% women). Data on coronary atherosclerosis, self-reported body weight at age 20 and measured midlife weight were recorded together with potential confounders and mediators. Coronary atherosclerosis was assessed using coronary computed tomography angiography (CCTA) and expressed as segment involvement score (SIS).The probability of having coronary atherosclerosis was markedly higher with increasing weight at age 20 and with mid-life weight (p<0.001 for both sexes). However, weight increase from age 20 until mid-life was only modestly associated with coronary atherosclerosis. The association between weight gain and coronary atherosclerosis was mainly seen in men. However, no significant sex difference could be detected when adjusting for the 10-year delay in disease development in women.Similar in men and women, weight at age 20 and weight in midlife are strongly related to coronary atherosclerosis while weight increase from age 20 until midlife is only modestly related to coronary atherosclerosis.
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| 13. |
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| 14. |
- Buhrman, Monica, 1974-, et al.
(författare)
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Guided internet-delivered acceptance and commitment therapy for chronic pain patients: A randomized controlled trial
- 2013
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Ingår i: Behaviour Research and Therapy. - : Elsevier. - 0005-7967 .- 1873-622X. ; 51:6, s. 307-315
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Tidskriftsartikel (refereegranskat)abstract
- Acceptance and commitment therapy (ACT) interventions for persons with chronic pain have recently received empirical support. ACT focuses on reducing the disabling influences of pain through targeting ineffective control strategies and teaches people to stay in contact with unpleasant emotions, sensations, and thoughts. The aim of the present study was to investigate the effect of a guided internet-delivered ACT intervention for persons with chronic pain. A total of 76 patients with chronic pain were included in the study and randomized to either treatment for 7 weeks or to a control group that participated in a moderated online discussion forum. Intent-to-treat analyses showed significant increases regarding activity engagement and pain willingness. Measurements were provided with the primary outcome variable Chronic Pain Acceptance Questionnaire which was in favour of the treatment group. Reductions were found on other measures of pain-related distress, anxiety and depressive symptoms. A six month follow-up showed maintenance of improvements. We conclude that an acceptance based internet-delivered treatment can be effective for persons with chronic pain.
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| 15. |
- Cabak Rédei, Anna, et al.
(författare)
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Applying cartosemiotics to rock art : An example from Aspeberget, Sweden
- 2019
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Ingår i: Social Semiotics. - Abingdon-on-Thames : Taylor & Francis. - 1035-0330 .- 1470-1219. ; 29:4, s. 543-556
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Tidskriftsartikel (refereegranskat)abstract
- This study aims to shed new light on the petroglyphs found at the site of Aspeberget 12 at the World Heritage site of Tanum, Sweden, from a semiotic perspective. We demonstrate the semiotics of power inherent in the arrangement of the petroglyphs. We start by describing the site in an archaeological way, in order to give an overview of the empirical material used in this case study. Against the backdrop of the overview, we introduce our analytical tools with reference to cartosemiotics, cultural semiotics and, Charles Sanders Peirce’s theory of signs. We suggest, in a tentative conclusion, that Aspeberget 12, as a type of“map”, displays a clear“Ego-culture”and a possible journey. We also suggest that the visual narratives at Aspeberget 12 represent the authority of the Ego-culture and its development. Details of thefigurative images such as ships, axes and spears might have been displayed as markers of the high technological standard of the Ego-culture, and thus of power.
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| 16. |
- Cabak Rédei, Anna, et al.
(författare)
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Seeing different motifs in one picture : Identifying ambiguous figures in South Scandinavian Bronze Age rock art
- 2020
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Ingår i: Cogent Arts & Humanities. - : Informa UK Limited. - 2331-1983. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Ambiguous figures, as described in visual perceptual psychology, are single pictures that contain several possible, mutually exclusive, motifs. Some specific cases of images in South Scandinavian Bronze Age rock art can be fruitfully analysed as ambiguous figures. Furthermore, we argue that these images represent some sort of narrativity, which needs to be understood in order to make a perceptual switch between different motifs in one picture. Using a semiotic approach, we describe the experiential requirements on the perceiver for seeing the different motifs, which differ in their iconic complexity.
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| 17. |
- Engström, Gunnar, et al.
(författare)
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Pulmonary function and atherosclerosis in the general population : causal associations and clinical implications
- 2024
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Ingår i: European Journal of Epidemiology. - : Springer Nature. - 0393-2990 .- 1573-7284. ; 39:1, s. 35-49
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Tidskriftsartikel (refereegranskat)abstract
- Reduced lung function is associated with cardiovascular mortality, but the relationships with atherosclerosis are unclear. The population-based Swedish CArdioPulmonary BioImage study measured lung function, emphysema, coronary CT angiography, coronary calcium, carotid plaques and ankle-brachial index in 29,593 men and women aged 50–64 years. The results were confirmed using 2-sample Mendelian randomization. Lower lung function and emphysema were associated with more atherosclerosis, but these relationships were attenuated after adjustment for cardiovascular risk factors. Lung function was not associated with coronary atherosclerosis in 14,524 never-smokers. No potentially causal effect of lung function on atherosclerosis, or vice versa, was found in the 2-sample Mendelian randomization analysis. Here we show that reduced lung function and atherosclerosis are correlated in the population, but probably not causally related. Assessing lung function in addition to conventional cardiovascular risk factors to gauge risk of subclinical atherosclerosis is probably not meaningful, but low lung function found by chance should alert for atherosclerosis.
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| 18. |
- Fytagoridis, Anders, et al.
(författare)
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Surgical Replacement of Implantable Pulse Generator in Deep Brain Stimulation : Adverse Events and Risk Factors in a Multicenter Cohort
- 2016
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Ingår i: Stereotactic and Functional Neurosurgery. - : S. Karger AG. - 1011-6125 .- 1423-0372. ; 94:4, s. 235-239
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Tidskriftsartikel (refereegranskat)abstract
- Background: Deep brain stimulation (DBS) is a growing treatment modality, and most DBS systems require replacement of the implantable pulse generator (IPG) every few years. The literature regarding the potential impact of adverse events of IPG replacement on the longevity of DBS treatments is rather scarce. Objective: To investigate the incidence of adverse events, including postoperative infections, associated with IPG replacements in a multicenter cohort. Methods: The medical records of 808 patients from one Australian and five Swedish DBS centers with a total of 1,293 IPG replacements were audited. A logistic regression model was used to ascertain the influence of possible predictors on the incidence of adverse events. Results: The overall incidence of major infections was 2.3% per procedure, 3.7% per patient and 1.7% per replaced IPG. For 28 of 30 patients this resulted in partial or complete DBS system removal. There was an increased risk of infection for males (OR 3.6, p = 0.026), and the risk of infection increased with the number of prior IPG replacements (OR 1.6, p < 0.005). Conclusions: The risk of postoperative infection with DBS IPG replacement increases with the number of previous procedures. There is a need to reduce the frequency of IPG replacements.
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| 19. |
- Granström, Anna Löf, et al.
(författare)
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No increased risk of attention deficit hyperactivity disorders in patients with Hirschsprung disease.
- 2019
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Ingår i: Journal of Pediatric Surgery. - : Elsevier BV. - 0022-3468 .- 1531-5037. ; 54:10, s. 2024-2027
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Hirschsprung disease (HSCR) has previously been associated with increased need of special education services despite normal intelligence. The aim of this study was to assess the risk of attention deficit hyperactivity disorders (ADHD) in individuals with HSCR in a population-based cohort.METHODS: This was a nationwide, population-based cohort study. The study exposure was HSCR and the study outcome was ADHD. The cohort included all individuals with HSCR registered in the Swedish National Patient Register between 1964 and 2013 and ten age- and sex-matched controls per patient, randomly selected from the Population Register.RESULTS: The cohort comprised 739 individuals with HSCR and 7390 controls. Twenty-six of the 739 individuals with HSCR and 202 of the 7390 controls were diagnosed with ADHD, Odds ratio (OR) 1.30, Confidence interval (CI) 95% 0.84-1.93, indicating no difference in risk for ADHD. The mean age at diagnosis of ADHD was not different between the groups; 18.1 years (SD 8.4) vs 16.7 years (SD 7.8), p = 0.39. Down syndrome did not affect the risk for ADHD, OR 2.26 (CI 95% 0.68-5.53). Female gender decreased the risk for ADHD, OR 0.58 (CI 95% 0.40-0.83).CONCLUSIONS: There is no increased risk of ADHD in patients with Hirschsprung disease.LEVEL OF EVIDENCE: Prognosis study, level of evidence: Level I.
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| 20. |
- Granström, Anna Löf, et al.
(författare)
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Selective serotonin reuptake inhibitors during pregnancy Do not increase the risk of Hirschsprung disease.
- 2019
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Ingår i: Journal of Pediatric Surgery. - : Elsevier BV. - 0022-3468 .- 1531-5037. ; 54:11, s. 2398-2401
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Hirschsprung disease (HSCR) is a multifactorial disease. Maternal intake of selective serotonin reuptake inhibitors (SSRI) during early pregnancy has previously been associated with increased risk for HSCR. The aim of this study was to assess the risk for HSCR in newborns after maternal intake of SSRI in a population-based Swedish cohort.METHODS: This was a Swedish nationwide, population-based, case-control cohort study containing all children born in Sweden between 1/12006 and 31/122012. The cases were identified in the Swedish National Patient Register and the controls (five age- and sex-matched controls per case) were randomly selected among children without HSCR in the cohort. Data on maternal SSRI use during pregnancy were collected from the Swedish Prescribed Drug Register.RESULTS: Out of 775,024 born children during the study period, 150 cases of HSCR (112 males) and 750 controls (560 males) were included. Five (3.3%) mothers of newborns with HSCR had used SSRI during pregnancy compared to 16 (2.1%) mothers of the controls (p = 0.372). The mean age was similar in mothers who had used SSRI compared to those who had not (30.9 (SD +/- 5.1) versus 30.6 (SD +/- 5.0), p = 0.81).CONCLUSIONS: There was no increased risk of HSCR owing to maternal intake of SSRI in this cohort.LEVEL OF EVIDENCE: Level I.
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| 21. |
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| 22. |
- Hagstrom, Emil, et al.
(författare)
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IMPACT OF BODY WEIGHT AT AGE 20 AND WEIGHT GAIN DURING ADULTHOOD ON MIDLIFE CORONARY ARTERY CALCIUM IN 15,000 MEN AND WOMEN : AN INTERIM ANALYSIS OF THE SWEDISH CARDIOPULMONARY BIOIMAGE STUDY
- 2019
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Ingår i: Journal of the American College of Cardiology. - : ELSEVIER SCIENCE INC. - 0735-1097 .- 1558-3597. ; 73:9, s. 1692-1692
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- BackgroundElevated body weight in adolescence is strongly associated with early cardiovascular disease, but whether this association is traceable to weight in early adulthood, or to weight gain with subsequent high adult weight is not known. Using data from the Swedish CArdioPulmonary bioImage Study (SCAPIS), we investigated the association between weight at age 20, weight gain to midlife and coronary artery calcium score (CACS) at midlife.MethodsIn the first 15,810 participants in SCAPIS (mean age 58 years, 52% women), data on CACS at midlife, self-reported body weight at age 20 and weight at examination in SCAPIS were recorded.ResultsCACS in midlife was significantly higher with increasing weight at age 20 (p<0.001 for both sexes), and then increased with weight gain until midlife at all levels of body weight at age 20 after adjusting for age, height, smoking, alcohol intake, education level, exercise levels and LDL cholesterol. However, the association with weight gain was only significant in men (p = 0.047), not in women (p=0.474). No significant interaction was seen between weight at age 20 and midlife weight with CACS. The effect of weight at age 20 on CACS was significantly more marked in men than in women, as was the effect of weight gain (p<0.001 for both interactions).ConclusionWeight at age 20 and weight gain to midlife were both related to CACS, but much more markedly so in men than in women, indicating a generally larger effect of both early adult weight and further weight gain until midlife on CACS in men, compared to women.
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| 23. |
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| 24. |
- Håkansson Eklund, Jakob, 1971-, et al.
(författare)
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Same same or different? A review of reviews of person-centred and patient-centred care.
- 2019
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Ingår i: Patient Education and Counseling. - : Elsevier BV. - 0738-3991 .- 1873-5134. ; :1, s. 3-11
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Tidskriftsartikel (refereegranskat)abstract
- ObjectiveTo provide a synthesis of already synthesized literature on person-centered care and patient-centered care in order to identify similarities and differences between the two concepts.MethodsA synthesis of reviews was conducted to locate synthesized literature published between January 2000 and March 2017. A total of 21 articles deemed relevant to this overview were synthesized using a thematic analysis.ResultsThe analysis resulted in nine themes present in person-centered as well as in patient-centered care: (1) empathy, (2), respect (3), engagement, (4), relationship, (5) communication, (6) shared decision-making, (7) holistic focus, (8), individualized focus, and (9) coordinated care. The analysis also revealed that the goal of person-centered care is a meaningful life while the goal of patient-centered care is a functional life.ConclusionsWhile there are a number of similarities between the two concepts, the goals for person-centered and patient-centered care differ. The similarities are at the surface and there are important differences when the concepts are regarded in light of their different goals.Practice implicationsClarification of the concepts may assist practitioners to develop the relevant aspects of care. Person-centered care broadens and extends the perspective of patient-centered care by considering the whole life of the patient.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Lundin, Henrik, et al.
(författare)
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Analog-to-Digital Converter Error Correction using Frequency Selective Tables
- 2002
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Ingår i: RadioVetenskap och Kommunikation (RVK). ; , s. 487-490
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Error correction for analog-to-digital converters(ADCs) is considered. The frequency-dependent na-ture of ADC errors motivates the proposal of a novel scheme, incorporating look-up table correction andfast frequency estimation. The method is evaluated using experimental converter data, and the performance, measured in SFDR and SINAD, is found tobe superior to that of non frequency-dependent correction methods.
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| 29. |
- Oberg, Johanna, et al.
(författare)
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Age related changes in brain metabolites observed by 1H MRS in APP/PS1 mice
- 2008
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Ingår i: Neurobiology of Aging. - : Elsevier BV. - 0197-4580 .- 1558-1497. ; 29:9, s. 1423-1433
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Tidskriftsartikel (refereegranskat)abstract
- Translational biomarkers in Alzheimer's disease based on non-invasive in vivo methods are highly warranted. (1)H magnetic resonance spectroscopy (MRS) is non-invasive and applicable in vivo in both humans and experimental animals. In vivo(1)H MRS and 3D MRI were performed on brains of double transgenic (tg) mice expressing a double mutant human beta-amyloid precursor protein APP(K670N,M671L) and human mutated presenilin gene PS1M146L, and wild-type (wt) littermates at 2.5, 6.5 and 9 months of age using a 9.4T magnet. For quantification, LCModel was used, and the data were analyzed using multivariate data analysis (MVDA). MVDA evidenced a significant separation, which became more pronounced with age, between tg and wt mice at all time points. While myo-inositol and guanidoacetate were important for group separation in young mice, N-acetylaspartate, glutamate and macrolipids were important for separation of aged tg and wt mice. Volume segmentation revealed that brain and hippocampus were readily smaller in tg as compared to wt mice at the age of 2.5 months. Amyloid plaques were seen in 6.5 and 9 months, but not in 2.5 months old animals. In conclusion, differences in brain metabolites could be accurately depicted in tg and wt mice in vivo by combining MRS with MVDA. First differences in metabolite content were readily seen at 2.5 months, when volume defects in tg mice were present, but no amyloid plaques.
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| 30. |
- Ohm, Joel, et al.
(författare)
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Association of Socioeconomic Status With Risk Factor Target Achievements and Use of Secondary Prevention After Myocardial Infarction
- 2021
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Ingår i: JAMA Network Open. - : American Medical Association (AMA). - 2574-3805. ; 4:3
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Tidskriftsartikel (refereegranskat)abstract
- IMPORTANCE Low socioeconomic status (SES) is associated with poor long-term prognosis after myocardial infarction (MI). Plausible underlying mechanisms have received limited study. OBJECTIVE To assess whether SES is associated with risk factor target achievements or with riskmodifying activities, including cardiac rehabilitation programs, monitoring, and drug therapies, during the first year after MI. DESIGN, SETTING, AND PARTICIPANTS This cohort study included a population-based consecutive sample of 30 191 one-year survivors of first-ever MI who were 18 to 76 years of age, resided in the general community in Sweden, were followed up until their routine 11- to 15-month revisit, and were registered in the national registry SwedishWeb-System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART) from 2006 through 2013. Data analyses were performed from January to August 2020. EXPOSURE Individual-level SES by proxy disposable income quintile. Secondary exposures were educational level and marital status. MAIN OUTCOMES AND MEASURES Odds ratios (ORs) with 95% CIs for achieved risk factor targets at the 1-year revisit and for use of guideline-recommended secondary prevention activities. RESULTS The study comprised 30 191 participants ( 72.9% men) with a mean (SD) age of 63.0 (8.6) years. Overall, higher SESwas associated with better target achievements and use of most secondary prevention. The highest (vs lowest) income quintilewas associated with achieved smoking cessation (OR, 2.05; 95% CI, 1.78-2.35), target blood pressure levels (OR, 1.17; 95% CI, 1.07-1.27), and glycated hemoglobin levels (OR, 1.57; 95% CI, 1.19-2.06). The highest-income quintile was associated not only with participation in physical training programs (OR, 2.28; 95% CI, 2.11-2.46) and patient educational sessions (OR, 2.29; 95% CI, 2.12-2.47) in cardiac rehabilitation but also with more monitoring of lipid profiles (OR, 1.20; 95% CI, 1.08-1.33) and intensification of statin therapy (OR, 1.22; 95% CI, 1.11-1.35) during the first year after MI. One year after MI, the highest-income quintile was associated with persistent use of statins (OR, 1.26; 95% CI, 1.10-1.45), high-intensity statins (OR, 1.10; 95% CI, 1.00-1.21), and renin-angiotensin-aldosterone system inhibitors (OR, 1.27; 95% CI, 1.08-1.49). CONCLUSIONS AND RELEVANCE Findings indicated that, in a publicly financed health care system, higher SES was associated with better achievement of most risk factor targets, programs aimed at lifestyle change, and evidence-based drug therapies after MI. Observed differences in secondary prevention activity may be a factor in higher long-term risk of recurrent disease among individuals with low SES.
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| 31. |
- Ohm, Joel, et al.
(författare)
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Lipid levels achieved after a first myocardial infarction and the prediction of recurrent atherosclerotic cardiovascular disease
- 2019
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Ingår i: International Journal of Cardiology. - : ELSEVIER IRELAND LTD. - 0167-5273 .- 1874-1754. ; 296, s. 1-7
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Tidskriftsartikel (refereegranskat)abstract
- Background: Low density lipoprotein cholesterol (LDL-C) goals post-myocardial infarction (MI) are debated, and the significance of achieved blood lipid levels for predicting a first recurrent atherosclerotic cardiovascular disease (rASCVD) event post-MI is unclear.Methods: This was a cohort study on first-ever MI survivors aged <= 76 years attending 4-14 week revisits throughout Sweden 2005-2013. Personal-level data was collected from SWEDEHEART and linked national registries. Exposures were quintiles of LDL-C, high density lipoprotein cholesterol (HDL-C), total cholesterol (TC), and triglycerides (TGs) at the revisit. Group level associations with rASCVD (nonfatal MI or coronary heart disease death or fatal or nonfatal ischemic stroke) were estimated in Cox regression models. Predictive capacity was estimated by differences in C-statistic, integrated discriminatory improvement, and net reclassification improvement when adding each blood lipid to a validated risk prediction model.Results: 25,643 patients, 96.9% on statin therapy, were followed during a mean of 4.1 years. rASCVD occurred in 2173 patients (8.5%). For LDL-C and TC, moderate associations with rASCVD were observed only in the 5th vs. the lowest (referent) quintiles. For TGs and HDL-C increased risks were observed in quintiles 3-5 vs. the lowest. Minor predictive improvements were observed when lipid fractions were added to the risk model but the discrimination overall was poor (C-statistics < 0.6).Conclusions: Our data question the importance of LDL-C levels achieved at first revisit post-MI for decisions on continued treatment intensity considering the weak association with rASCVD observed in this post-MI cohort.
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| 32. |
- Ohm, Joel, et al.
(författare)
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Socioeconomic Disparities and Mediators for Recurrent Atherosclerotic Cardiovascular Disease Events After a First Myocardial Infarction
- 2023
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Ingår i: Circulation. - : Lippincott Williams & Wilkins. - 0009-7322 .- 1524-4539. ; 148:3, s. 256-267
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND:Low socioeconomic status is associated with worse secondary prevention use and prognosis after myocardial infarction (MI). Actions for health equity improvements warrant identification of risk mediators. Therefore, we assessed mediators of the association between socioeconomic status and first recurrent atherosclerotic cardiovascular disease event (rASCVD) after MI.METHODS:In this cohort study on 1-year survivors of first-ever MI with Swedish universal health coverage ages 18 to 76 years, individual-level data from SWEDEHEART (Swedish Web System for Enhancement and Development of Evidence-Based Care in Heart Disease Evaluated According to Recommended Therapies) and linked national registries was collected from 2006 through 2020. Exposure was socioeconomic status by disposable income quintile (principal proxy), educational level, and marital status. The primary outcome was rASCVD and secondary outcomes were cardiovascular and all-cause mortality. We initially assessed the incremental attenuation of hazard ratios with 95% CIs in sequential multivariable models adding groups of potential mediators (ie, previous risk factors, acute presentation and infarct severity, initial therapies, and secondary prevention). Thereafter, the proportion of excess rASCVD associated with a low income mediated through nonparticipation in cardiac rehabilitation, suboptimal statin management, a cardiometabolic risk profile, persistent smoking, and blood pressure above target after MI were calculated using causal mediation analysis.RESULTS:Among 68 775 participants (73.8% men), 7064 rASCVD occurred during a mean 5.7-year follow-up. Income, adjusted for age, sex, and calendar year, was associated with rASCVD (hazard ratio, 1.63 [95% CI, 1.51-1.76] in the lowest versus highest income quintile). Risk attenuated most by adjustment for previous risk factors and by adding secondary prevention variables for a final model (hazard ratio, 1.38 [95% CI, 1.26-1.51]) in the lowest versus highest income quintile. The proportions of the excess 15-year rASCVD risk in the lowest income quintile mediated through nonparticipation in cardiac rehabilitation, cardiometabolic risk profile, persistent smoking, and poor blood pressure control were 3.3% (95% CI 2.1-4.8), 3.9% (95% CI, 2.9-5.5), 15.2% (95% 9.1-25.7), and 1.0% (95% CI 0.6-1.5), respectively. Risk mediation through optimal statin management was negligible.CONCLUSIONS:Nonparticipation in cardiac rehabilitation, a cardiometabolic risk profile, and persistent smoking mediate income-dependent prognosis after MI. In the absence of randomized trials, this causal inference approach may guide decisions to improve health equity.
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| 33. |
- Ohm, Joel, et al.
(författare)
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Socioeconomic status predicts second cardiovascular event in 29,226 survivors of a first myocardial infarction
- 2018
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Ingår i: European Journal of Preventive Cardiology. - : SAGE PUBLICATIONS LTD. - 2047-4873 .- 2047-4881. ; 25:9, s. 985-993
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Tidskriftsartikel (refereegranskat)abstract
- Background Risk assessment post-myocardial infarction needs improvement, and risk factors derived from general populations apply differently in secondary prevention. The prediction of subsequent cardiovascular events post-myocardial infarction by socioeconomic status has previously been poorly studied. Design Swedish nationwide cohort study. Methods A total of 29,226 men and women (27%), 40-76 years of age, registered at the standardised one year revisit after a first myocardial infarction in the secondary prevention quality registry of SWEDEHEART 2006-2014. Personal-level data on socioeconomic status measured by disposable income and educational level, marital status, and the primary endpoint, first recurrent event of atherosclerotic cardiovascular disease, defined as non-fatal myocardial infarction or coronary heart disease death or fatal or non-fatal stroke were obtained from linked national registries. Results During the mean 4.1-year follow-up, 2284 (7.8%) first recurrent manifestations of atherosclerotic cardiovascular disease occurred. Both socioeconomic status indicators and marital status were associated with the primary endpoint in multivariable Cox regression models. In a comprehensively adjusted model, including secondary preventive treatment, the hazard ratio for the highest versus lowest quintile of disposable income was 0.73 (95% confidence interval 0.62-0.83). The association between disposable income and first recurrent manifestation of atherosclerotic cardiovascular disease was stronger in men as was the risk associated with being unmarried (tests for interaction P<0.05). Conclusions Among one year survivors of a first myocardial infarction, first recurrent manifestation of atherosclerotic cardiovascular disease was predicted by disposable income, level of education and marital status. The association between disposable income and first recurrent manifestation of atherosclerotic cardiovascular disease was independent of secondary preventive treatment but further study on causal pathways is needed.
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| 34. |
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| 35. |
- Ranta, Michael, et al.
(författare)
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Hunting stories in Scandinavian rock art : Aspects of 'tellability' in the north versus the south
- 2020
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Ingår i: Oxford Journal of Archaeology. - : John Wiley & Sons. - 0262-5253 .- 1468-0092. ; 39:3, s. 228-246
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Tidskriftsartikel (refereegranskat)abstract
- Scandinavian petroglyphs have given rise to vivid interpretations, often related to Old Norse religion and Indo-European mythology. However, we still do not know if, how or to what extent these images are really telling stories. In this paper, we shall analyse the ways in which Scandinavian northern and southern traditions (in Alta, Northern Norway and in Norrkoping, Middle Sweden, respectively) depict hunting narratives. While the northern tradition may render several phases and procedural aspects of the hunt, the southern one tends to be more focused on the killing itself, or the confrontational aspects of the hunt. A preliminary observation is that the scenes differ in ways that reflect not only different hunting traditions, but also imply different foci of interest. Put in another way, they emphasize different aspects of the hunting activity itself, of what is relevant, worth telling, or 'tellable'.
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| 36. |
- Ranta, Michael, et al.
(författare)
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Levels of Narrativity in Scandinavian Bronze Age Petroglyphs
- 2019
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Ingår i: Cambridge Archaeological Journal. - : Cambridge University Press. - 1474-0540 .- 0959-7743. ; 29:3, s. 497-516
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Tidskriftsartikel (refereegranskat)abstract
- In Europe, Scandinavia holds the largest concentration of rock art (i.e. petroglyphs), created c. 5000–first century bc, many of them showing figurative and seemingly narrative representations. In this paper, we will discuss possible narratological approaches applied to these images. We might reasonably distinguish between three levels of pictorial narrativity: representations of (i) single events, understood as the transition from one state of affairs to another, usually involving (groups of) agents interacting; (ii) stories, e.g. particular sequences of related events that are situated in the past and retold for e.g. ideological or religious purposes; and (iii) by implication, master-narratives deeply embedded in a culture, which provide and consolidate cosmological explanations and social structures. Some concrete examples of petroglyphs will be presented and analysed from narratological and iconographical perspectives. We will as a point of departure focus on (i), i.e. single events, though we shall also further consider the possibility of narrative interpretations according to (ii) and (iii).
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| 37. |
- Rodríguez-Varela, Ricardo, et al.
(författare)
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The genetic history of Scandinavia from the Roman Iron Age to the present
- 2023
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Ingår i: Cell. - : Elsevier. - 0092-8674 .- 1097-4172. ; 186:1, s. 32-46
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Tidskriftsartikel (refereegranskat)abstract
- We investigate a 2,000-year genetic transect through Scandinavia spanning the Iron Age to the present, based on 48 new and 249 published ancient genomes and genotypes from 16,638 modern individuals. We find regional variation in the timing and magnitude of gene flow from three sources: the eastern Baltic, the British-Irish Isles, and southern Europe. British-Irish ancestry was widespread in Scandinavia from the Viking period, whereas eastern Baltic ancestry is more localized to Gotland and central Sweden. In some regions, a drop in current levels of external ancestry suggests that ancient immigrants contributed proportionately less to the modern Scandinavian gene pool than indicated by the ancestry of genomes from the Viking and Medieval periods. Finally, we show that a north-south genetic cline that characterizes modern Scandinavians is mainly due to the differential levels of Uralic ancestry and that this cline existed in the Viking Age and possibly earlier.
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| 38. |
- Shahsavari, Sima, 1976, et al.
(författare)
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A comparison between the transfer function of ABP to ICP and compensatory reserve index in TBI
- 2008
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Ingår i: Acta Neurochirurgica, Supplement. - Vienna : Springer Vienna. - 0065-1419. - 9783211855775 ; 102:102, s. 9-13
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: The transfer functions which map the arterial blood pressure to the intracranial pressure and the compensatory reserve index have been investigated by various groups to evaluate the brain compliance of patients with traumatic brain injury. The focus of this study has been to assess the capability of both the above mentioned methods to monitor the intracranial compliance in patients suffering from brain swelling. MATERIALS AND METHODS: Clinical data was collected from sixteen traumatic brain injury patients and split into 4 min segments. For each segment, both the magnitude of the empirical transfer function at the fundamental cardiac frequency and the compensatory reserve index were extracted. FINDINGS: The mean values of the compensatory reserve index and the magnitude of the transfer function which scored higher than 0.7 and 0.1 respectively were recorded for all patients suffering from brain swelling. By comparing the histogram of the magnitude of the transfer function at the fundamental cardiac frequency with the histogram of the compensatory reserve index for all patients, a positive correlation between the mean values and a negative correlation among their variances were observed. The linear correlation between the mean values was estimated at r = 0.82 (p
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| 39. |
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| 40. |
- Sinding, Mikkel-Holger S., et al.
(författare)
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Arctic-adapted dogs emerged at the Pleistocene-Holocene transition
- 2020
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 368:6498
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Tidskriftsartikel (refereegranskat)abstract
- Although sled dogs are one of the most specialized groups of dogs, their origin and evolution has received much less attention than many other dog groups. We applied a genomic approach to investigate their spatiotemporal emergence by sequencing the genomes of 10 modern Greenland sled dogs, an similar to 9500-year-old Siberian dog associated with archaeological evidence for sled technology, and an similar to 33,000-year-old Siberian wolf. We found noteworthy genetic similarity between the ancient dog and modern sled dogs. We detected gene flow from Pleistocene Siberian wolves, but not modern American wolves, to present-day sled dogs. The results indicate that the major ancestry of modern sled dogs traces back to Siberia, where sled dog-specific haplotypes of genes that potentially relate to Arctic adaptation were established by 9500 years ago.
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| 41. |
- Skoglund, Oliver, et al.
(författare)
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Fighting Fatigue in Systemic Lupus Erythematosus : Experience of Dehydroepiandrosterone on Clinical Parameters and Patient-Reported Outcomes
- 2022
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Ingår i: Journal of Clinical Medicine. - : MDPI. - 2077-0383. ; 11:18
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Tidskriftsartikel (refereegranskat)abstract
- Manifestations related to ongoing inflammation in systemic lupus erythematosus (SLE) are often adequately managed, but patient-reported outcome measures (PROMs) support that fatigue and low quality of life (QoL) in the absence of raised disease activity remain major burdens. The adrenal hormone dehydroepiandrosterone (DHEA) has shown potential as a pharmacological agent for managing fatigue in mild SLE. We retrospectively evaluated data on dosage, disease activity, corticosteroid doses, concomitant antirheumatic drugs, and PROMs regarding pain intensity, fatigue, and well-being (visual analogue scales), QoL (EQ-5D-3L) and functional disability. A total of 15 patients with SLE were exposed to DHEA and 15 sex- and age-matched non-exposed SLE patients served as comparators. At baseline, 83% of the DHEA-exposed patients had subnormal DHEA concentration. The 15 subjects prescribed DHEA were exposed during a median time of 12 months (IQR 16.5) [range 3-81] and used a median daily dose of 50 mg of DHEA (IQR 25.0) [range 25-200]. Neither disease activity, nor damage accrual, changed significantly over time among patients using DHEA, and no severe adverse events were observed. Numerical improvements of all evaluated PROMs were seen in the DHEA-treated group, but none reached statistical significance. For DHEA-exposed patients, a non-significant trend was found regarding fatigue comparing baseline and 36 months (p = 0.068). In relation to SLE controls, the DHEA-exposed group initially reported significantly worse fatigue, pain, and well-being, but the differences diminished over time. In conclusion, DHEA was safe, but evidence for efficacy of DHEA supplementation in relation to PROMs were not found. Still, certain individuals with mild SLE, plagued by fatigue and absence of increased disease activity, appear to benefit from DHEA in terms of improved fatigue and QoL. Testing of DHEA concentration in blood should be performed before initiation, and investigation of other conditions, or reasons responsible for fatigue, must always be considered first.
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| 42. |
- Skoglund, Peter, et al.
(författare)
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A Multisensory Approach to Rock Art : Exploring Tactile and Visual Dimensions in the Southern Scandinavian Rock Art Tradition
- 2020
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Ingår i: Proceedings of the Prehistoric Society. - : Cambridge University Press. - 0079-497X .- 2050-2729. ; 86, s. 95-110
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Tidskriftsartikel (refereegranskat)abstract
- This paper discusses rock art in southern Scandinavia as a multisensory format, where both sight and touch would have contributed to the comprehension of the images. From a structural semiotic point of view, we suggest that rock art can be construed as an organised set of features, such as visual and tactile elements, organised into heterogeneous unities with dynamic relations between elements that can change over time with respect to how they are experienced. We argue that in order to understand the rock art medium, it is crucial to take into consideration the multisensory interaction between the perceiver and the qualities of the rock art surface. The reason for including tactile elements in our interpretation of the conception of rock art is the way it was created: by hands interacting with tools and rock surfaces, as well as the spontaneous human tendency to explore the physical world through touch. One can identify key features in the images that would arguably facilitate tactile recognition, as well as be better explained from a multisensorial perspective. This includes the position of the images on horizontal outcrops, the moderate size of the images, the application of an orthographic perspective, the use of ‘tactile markers’ (ie crucial features having a strategic function for understanding images by touch), and the occurrence of incomplete images. A multisensorial perspective on rock art furthermore has semiotic implications. Incomplete images, for example, can be understood as indexical stand-ins for the whole imagined picture, ie as iconic indices. A multisensorial approach to Scandinavian rock art thus allows for new explanations for certain design choices, as well as a new understanding of how the images could relay meaning to a perceiver.
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| 43. |
- Skoglund, Peter, et al.
(författare)
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A Narrative Turn : Human Agency in Rock Carvings at Nämforsen, Northern Sweden
- 2023
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Ingår i: Oxford Journal of Archaeology. - : John Wiley & Sons. - 0262-5253 .- 1468-0092. ; 42:4, s. 301-321
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Tidskriftsartikel (refereegranskat)abstract
- The idea to create pictorial narratives seems to have occurred long after humans learned to produce iconic images, that is, depictions based on visual similarity to external objects. In Scandinavia, e.g. in Gärde, Sweden or Stykket and Bøla, Norway, early Mesolithic images (e.g. rock carvings from before c.5000 BCE) often feature animals that are solitary or without suggestion of causal or narrative relations to other figures, although they sometimes are grouped by proximity or are superimposed on each other. Notable is also the almost complete absence of human figures. However, in subsequent Neolithic configurations (after c.5000 BCE), there are renderings of human agents involved in various forms of interaction with each other or with animals, often within distinguishable ‘scenes’ or compositions.In this paper we outline the emergence of pictorial narratives in Scandinavian rock carvings. In particular, we focus on some of the first depictions of human agency as displayed in Nämforsen, Sweden (c.5000–1800 BCE). Further, we present an analysis of occurring human-animal relationships, interpretable as early attempts to create narrativizing images.
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| 44. |
- Skoglund, Peter, et al.
(författare)
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Narrative Aspects of Images of Spear Use in Scandinavian Rock Carvings
- 2021
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Ingår i: European Journal of Archaeology. - : Cambridge University Press (CUP). - 1461-9571 .- 1741-2722.
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Tidskriftsartikel (refereegranskat)abstract
- Researchers have long discussed whether Scandinavian rock art reflects narratives. Their interpretations have frequently been based on inspections of rock art panels combined with knowledge from ethnographic and historical sources. Here, the authors adopt a more focused narratological approach that takes the concept of (visual) narrativity into consideration and draws on studies by literary analysts, cognitive psychologists, and semioticians. Images of spear use in the provinces of Bohuslän and Östergötland in Sweden, given their diversity and indexical qualities, are well-suited to such a study. They reveal different kinds of indexical relationships, i.e. how the spears direct attention to possible targets, arguably corresponding to action scripts well-known to Bronze Age communities. Many spear images may be regarded as mini-narratives and mnemonic devices intended to represent schematized action sequences. The authors suggest that concepts such as iconicity, indexical relationships, scripts, and mini-narratives could be fruitfully employed in research on Scandinavian rock art and beyond.
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| 45. |
- Skoglund, Tomas, et al.
(författare)
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A dynamic object-oriented model for efficient simulation of fluid dispersion in turbulent flow with varying fluid properties
- 2007
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509. ; 62:8, s. 2168-2178
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Tidskriftsartikel (refereegranskat)abstract
- Dispersion coefficients for turbulent flow are commonly available, but the common models are not easily implemented for fast computation of dispersion in time-dependent large flow systems. Criteria were developed to aid in the choice of parameters for a model combining plug flow with the N-continuously stirred-tanks model to obtain the best agreement with the pure axial-dispersed plug-flow model, while simultaneously being computationally efficient. Solution accuracy and computational savings were demonstrated for a realistic food industry example. The proposed model includes a method of structuring the discretisation to handle the simulation of pressure drop and momentum balance simultaneously with simulation of dispersion. The criteria were derived from the analysis of Laplace transforms. It was also shown that the proposed model predicts the response to a step change in concentration in agreement with the exact solution of the axial-dispersed plug-flow model. The model was written in the object-oriented language Modelica as an object in a library structure which is being developed to simulate complex liquid food process lines and their control systems.
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| 46. |
- Skoglund, Tomas, et al.
(författare)
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A dynamic object-oriented model for efficient simulation of microbial reduction in dispersed turbulent flow
- 2008
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Ingår i: Journal of Food Engineering. - : Elsevier BV. - 0260-8774. ; 86:3, s. 358-369
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Tidskriftsartikel (refereegranskat)abstract
- To account for microbial reduction and food quality changes, first-order chemical reaction was added to a model for axial-dispersed plug flow (ADPF), which was recently developed for efficient (In the terminology of this paper, efficient is related to computation time for a given level of accuracy.) computation of time-dependent, large flow systems. It was shown that the extended ADPF model gives accurate results for typical parameter values in liquid-food applications. The analysis was based on Laplace transforms and the models were written in the object-oriented language Modelica, as objects in a library structure which is being developed to simulate complex liquid-food process lines and their control systems. The models were also implemented in such a way as to efficiently account for non-isothermal reactions in heat exchangers. Furthermore, to account for changes in flow rates, a model of dynamically calculating the “true” holding time in a channel was developed. Simulations showed that the model performs better than a straightforward alternative.
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| 47. |
- Skoglund, Tomas, et al.
(författare)
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A model library for dynamic simulation of liquid food process lines
- 2006
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Ingår i: Foodsim' 2006: 4th International Conference on Simulation and modelling in the Food and Bio-industry. ; , s. 5-12
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Konferensbidrag (refereegranskat)abstract
- Ongoing work in developing a general structure and a comprehensive components library aiming at modelling liquid-food process lines is presented. The dynamic component models were developed in an object-oriented library structure based on the dynamic modelling language Modelica using the object-oriented graphical tool Dymola. The models were based on fundamental conservation laws and can simulate one-dimensional dynamics in liquid-food plants including process control, in terms of flows, pressures, temperatures and compositions. Novel solutions were proposed to handle varying fluid properties during changeover in heat exchangers. Examples of simulations of cream and milk pasteurisation, juice blending and flash boiling for de-aeration of juice are given(1).
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| 48. |
- Skoglund, Tomas
(författare)
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Dynamic Modelling and Simulation of Liquid Food Process Lines
- 2007
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In the present work a dynamic model library of components for process lines was developed. The analysis addressed characteristic aspects of liquid food process lines, and new models were developed for fluid transitions, dispersion, mixing zones and first-order chemical reactions in pipes and heat exchangers. The computational efficiency and accuracy of the models were analysed. It was demonstrated that classical models of fluid propagation in process lines could be combined with modern numerical methods to obtain computationally efficient dynamic models for the simulation of dispersed convective flow, with and without chemical reactions. In particular it was demonstrated that a transport delay model was well suited for the simulation of thermal transients due to fluid transitions in heat exchangers. It was shown that the model could be extended to account for dispersion with a method that, although classical in approach, enables a certain freedom in the choice of degree of discretization depending on the demand for accuracy vs. computational speed. Further extension of the model with first-order chemical reactions to account for microbial deactivation was demonstrated. The usefulness of the dispersed-convection model to predict the extent of mixing zones and the amount of product rejects in continuous processing was demonstrated. The relevance concerning product traceability is discussed and the concept ?fuzzy traceability? introduced.
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| 49. |
- Skoglund, Tomas, et al.
(författare)
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Dynamic object-oriented heat exchanger models for simulation of fluid property transitions
- 2006
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Ingår i: International Journal of Heat and Mass Transfer. - : Elsevier BV. - 0017-9310. ; 49:13-14, s. 2291-2303
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Tidskriftsartikel (refereegranskat)abstract
- Object-oriented heat exchanger models were developed to simulate the dynamic thermal effects of dynamic changes in fluid composition and thus of fluid properties in a type of liquid typical for food products. The models were written in the object-oriented language Modelica as objects in a library structure being developed to simulate complex liquid food process lines and their control systems. The models were based on moderate discretization of the heat exchanger into control volumes, and the fluid dispersion was modelled either as ideal mixing or as transport delay in each control volume. The transport delay model exhibited the best computational performance as well as affording flexibility in fluid dispersion modelling. (
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| 50. |
- Skoglund, Tomas, et al.
(författare)
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Fuzzy traceability: A process simulation derived extension of the traceability concept in continuous food processing
- 2007
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Ingår i: Food and Bioproducts Processing. - : Elsevier BV. - 1744-3571 .- 0960-3085. ; 85:C4, s. 354-359
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in Undetermined Liquid food production often involves continuous processing. This leads to problems in traceability systems due to mixing zones and therefore indistinct batch identities causing difficulties with regard to withdrawals or recalls. This article outlines the possible use of the concept of dynamic simulation to improve the handling of batch identities in continuous production of liquid food, a concept we call fuzzy traceability. The concept is illustrated with a realistic example from a real dairy process line.
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