| 1. |
- Aleman, Soo, et al.
(författare)
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Health check-ups and family screening allow detection of hereditary hemochromatosis with less advanced liver fibrosis and survival comparable with the general population
- 2011
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 46:9, s. 1118-1126
-
Tidskriftsartikel (refereegranskat)abstract
- Objective. The information concerning the morbidity and mortality of hereditary hemochromatosis is based primarily on clinical cohorts of symptomatic patients. The major aim of this study was to analyze the long-term prognosis for Swedish patients with this condition, with respect to both clinical features and survival, in relation to the route by which the disease was detected. Patients and methods. 373 patients with hemochromatosis detected through routine health checkups (n = 153), family screening (n = 44), symptoms of arthralgia (n = 23), investigation of other diseases/symptoms (n = 108) or signs of liver disease (n = 45) were monitored for a mean period of 11.9 +/- 5.8 years. The degree of liver fibrosis and survival were analyzed. Results. Overall survival among these patients was not significantly different from that of a matched normal population. The patients diagnosed through health check-ups and family screening were detected at an earlier age and had the highest rate of survival. Liver biopsy at the time of diagnosis revealed cirrhosis in 9% of those detected through the health check-ups and 5% in the case of family screening, compared with 13% for the group with arthralgia, 17% for other diseases/symptoms and 42% for liver disease. Conclusion. Health check-ups and family screening allow detection of hereditary hemochromatosis at an earlier age and with less advanced liver fibrosis, although a few of these patients have already developed cirrhosis. Our study indicates that iron indices should be included in health check-ups, and if abnormal, should lead to further investigation.
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| 2. |
- Almér, Stefan, 1975-
(författare)
-
Control and Analysis of Pulse-Modulated Systems
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The thesis consists of an introduction and four appended papers. In the introduction we give an overview of pulse-modulated systems and provide a few examples of such systems. Furthermore, we introduce the so-called dynamic phasor model which is used as a basis for analysis in two of the appended papers. We also introduce the harmonic transfer function and finally we provide a summary of the appended papers. The first paper considers stability analysis of a class of pulse-width modulated systems based on a discrete time model. The systems considered typically have periodic solutions. Stability of a periodic solution is equivalent to stability of a fixed point of a discrete time model of the system dynamics. Conditions for global and local exponential stability of the discrete time model are derived using quadratic and piecewise quadratic Lyapunov functions. A griding procedure is used to develop a systematic method to search for the Lyapunov functions. The second paper considers the dynamic phasor model as a tool for stability analysis of a general class of pulse-modulated systems. The analysis covers both linear time periodic systems and systems where the pulse modulation is controlled by feedback. The dynamic phasor model provides an $\textbf{L}_2$-equivalent description of the system dynamics in terms of an infinite dimensional dynamic system. The infinite dimensional phasor system is approximated via a skew truncation. The truncated system is used to derive a systematic method to compute time periodic quadratic Lyapunov functions. The third paper considers the dynamic phasor model as a tool for harmonic analysis of a class of pulse-width modulated systems. The analysis covers both linear time periodic systems and non-periodic systems where the switching is controlled by feedback. As in the second paper of the thesis, we represent the switching system using the L_2-equivalent infinite dimensional system provided by the phasor model. It is shown that there is a connection between the dynamic phasor model and the harmonic transfer function of a linear time periodic system and this connection is used to extend the notion of harmonic transfer function to describe periodic solutions of non-periodic systems. The infinite dimensional phasor system is approximated via a square truncation. We assume that the response of the truncated system to a periodic disturbance is also periodic and we consider the corresponding harmonic balance equations. An approximate solution of these equations is stated in terms of a harmonic transfer function which is analogous to the harmonic transfer function of a linear time periodic system. The aforementioned assumption is proved to hold for small disturbances by proving the existence of a solution to a fixed point equation. The proof implies that for small disturbances, the approximation is good. Finally, the fourth paper considers control synthesis for switched mode DC-DC converters. The synthesis is based on a sampled data model of the system dynamics. The sampled data model gives an exact description of the converter state at the switching instances, but also includes a lifted signal which represents the inter-sampling behavior. Within the sampled data framework we consider H-infinity control design to achieve robustness to disturbances and load variations. The suggested controller is applied to two benchmark examples; a step-down and a step-up converter. Performance is verified in both simulations and in experiments.
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| 3. |
- Almér, Stefan, et al.
(författare)
-
Dynamic phasor analysis of a class of PWM systems
- 2015
-
Ingår i: 2007 European Control Conference, ECC 2007. - : IEEE. - 9783952417386 ; , s. 1940-1947
-
Konferensbidrag (refereegranskat)abstract
- The paper makes use of the so-called dynamic phasor model for stability and performance analysis of a class of PWM systems. The dynamic phasor model allows for the state to be represented in the frequency domain where a harmonic Lyapunov function is defined. The analysis covers both periodically switched systems and non-periodic systems where the switching is controlled by feedback.
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| 4. |
- Almér, Stefan, et al.
(författare)
-
Dynamic Phasor Analysis of Periodic Systems
- 2009
-
Ingår i: IEEE Transactions on Automatic Control. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9286 .- 1558-2523. ; 54:8, s. 2007-2012
-
Tidskriftsartikel (refereegranskat)abstract
- The paper considers stability analysis of linear time-periodic (LTP) systems based on the dynamic phasor model (DPM). The DPM exploits the periodicity of the system by expanding the system state in a Fourier series over a moving time window. This results in an L-2-equivalent representation in terms of an infinite-dimensional LTI system which describes the evolution of time varying Fourier coefficients. To prove stability, we consider quadratic time-periodic Lyapunov candidates. Using the DPM, the corresponding time-periodic Lyapunov inequality can be stated as a finite dimensional inequality and the Lyapunov function can be found by solving a linear matrix inequality.
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| 5. |
- Almér, Stefan, et al.
(författare)
-
Dynamic Phasor Analysis Of Pulse-Modulated Systems
- 2012
-
Ingår i: SIAM Journal of Control and Optimization. - : Society for Industrial & Applied Mathematics (SIAM). - 0363-0129 .- 1095-7138. ; 50:3, s. 1110-1138
-
Tidskriftsartikel (refereegranskat)abstract
- This paper considers stability and harmonic analysis of a general class of pulse-modulated systems. The systems are modeled using the dynamic phasor model, which explores the cyclic nature of the modulation functions by representing the system state as a Fourier series expansion defined over a moving time window. The contribution of the paper is to show that a special type of periodic Lyapunov function can be used to analyze the system and that the analysis conditions become tractable for computation after truncation. The approach provides a trade-off between complexity and accuracy that includes standard state space averaged models as a special case. The paper also shows how the dynamic phasor model can be used to derive a frequency domain input-to-state map which is analogous to the harmonic transfer function.
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| 6. |
- Almér, Stefan, et al.
(författare)
-
Dynamic phasor analysis of pulse-modulated systems
- 2007
-
Ingår i: Proceedings Of The 46th IEEE Conference On Decision And Control, Vols 1-14. - 9781424414970 ; , s. 3938-3945
-
Konferensbidrag (refereegranskat)abstract
- The paper considers stability analysis of a general class of pulse modulated systems in a phasor dynamic framework. The dynamic phasor model exploits the cyclic nature of the modulation functions by representing the system dynamics in terms of a Fourier series expansion defined over a moving time-window. The contribution of the paper is to show that a special type of periodic Lyapunov function can be used to analyze the system and that the analysis conditions become tractable for computation after truncation. The approach provides a trade-off between complexity and accuracy that includes standard state space averaged models as a special case.
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| 7. |
- Almér, Stefan, et al.
(författare)
-
Global stability analysis of DC-DC converters using sampled-data modeling
- 2004
-
Ingår i: PROCEEDINGS OF THE 2004 AMERICAN CONTROL CONFERENCE, VOLS 1-6. - 0780383354 ; , s. 4549-4554
-
Konferensbidrag (refereegranskat)abstract
- The paper presents stability analysis of a class of pulse-width modulated (PWM) systems which incorporates many different DC-DC converters. Two types of pulse-width modulation (digital and analog control) are considered. A procedure is developed for systematic search for Lyapunov functions. The state space is partitioned in such a way that stability is verified if a set of coupled Linear Matrix Inequalities (LMIs) is feasible. Global stability is considered as well as the computation of local regions of attraction.
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| 8. |
- Almer, Sven, 1938-, et al.
(författare)
-
Handläggning av svårt skov av ulcerös kolit. In: Löfberg R (ed): Inflammatorisk tarmsjukdom.
- 2010
-
Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 106:45, s. 62-75
-
Tidskriftsartikel (refereegranskat)abstract
- Patienter med svårt skov av ulcerös kolit bör vårdas på sjukhus och handläggas av gastroenterolog och kolorektal kirurg i nära samarbete.Skovets svårighetsgrad kan underskattas, varför noggrann bedömning av inflammationens utbredning och svårighetsgrad enligt validerade kriterier är viktigt.Intravenös behandling med kortikosteroider är en av hörnstenarna i den akuta behandlingen.Patienter som inte förbättras på denna behandling, bör erbjudas medicinsk »rescue-behandling« eller kolektomi.Infliximab har visats vara en effektiv rescue-behandling och kan minska behovet av kolektomi inom de första 3 månaderna och upp till 3 år.
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| 9. |
- Almér, Stefan, et al.
(författare)
-
Harmonic analysis of pulse-width modulated systems
- 2009
-
Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 45:4, s. 851-862
-
Tidskriftsartikel (refereegranskat)abstract
- The paper considers the so-called dynamic phasor model as a basis for harmonic analysis of a class switching systems. The analysis covers both periodically switched systems and non-periodic systems where the switching is controlled by feedback. The dynamic phasor model is a powerful tool for exploring cyclic properties of dynamic systems. It is shown that there is a connection between the dynamic phasor model and the harmonic transfer function of a linear time periodic system and this connection is used to extend the notion of harmonic transfer function to describe periodic solutions of non-periodic systems.
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| 10. |
- Almér, Stefan, et al.
(författare)
-
Harmonic Lyapunov functions in the analysis of periodically switched systems
- 2006
-
Ingår i: PROCEEDINGS OF THE 45TH IEEE CONFERENCE ON DECISION AND CONTROL, VOLS 1-14. - 9781424401703 ; , s. 2759-2764
-
Konferensbidrag (refereegranskat)abstract
- The dynamic phasor model of a time-periodic system is used to derive a stability test involving a harmonic Lyapunov function. This reveals a new interpretation of the harmonic Lyapunov function with an appealing time-domain representation. Most importantly, it indicates that the ideas behind the harmonic Lyapunov equation can be generalized to include cyclic switching systems that have different pulse form in each period.
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| 11. |
- Almér, Stefan, et al.
(författare)
-
Hybrid control techniques for switched-mode DC-DC converters part I : The step-down topology
- 2007
-
Ingår i: 2007 American Control Conference. - : IEEE. - 1424409888 - 9781424409884 ; , s. 5450-5457
-
Konferensbidrag (refereegranskat)abstract
- Several recent techniques from hybrid and optimal control are evaluated on a power electronics benchmark problem. The benchmark involves a number of practically interesting operating scenarios for a fixed-frequency synchronous step-down dc-dc converter. The specifications are defined such that good performance only can be obtained if the switched and nonlinear nature of the problem is respected during the design phase.
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| 12. |
|
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| 13. |
- Almér, Stefan, et al.
(författare)
-
Stability analysis of a class of PWM systems
- 2007
-
Ingår i: IEEE Transactions on Automatic Control. - 0018-9286 .- 1558-2523. ; 52:6, s. 1072-1078
-
Tidskriftsartikel (refereegranskat)abstract
- This note considers stability analysis of a class of pulsewidth modulated (PWM) systems that incorporates several different switched mode dc-de- converters. The systems of the class typically have periodic solutions. A sampled data model is developed and used to prove stability of these solutions. Conditions for global and local exponential stability are derived using quadratic and piecewise quadratic Lyapunov functions. The state space is partitioned and the stability conditions are verified by checking a set of coupled linear matrix inequalities (LMIs).
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| 14. |
- Angelison, Leif, et al.
(författare)
-
Short and long-term efficacy of adalimumab in ulcerative colitis : a real-life study
- 2020
-
Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 55:2, s. 154-162
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: Randomized controlled trials have shown the effectiveness of Adalimumab in ulcerative colitis. However, real-life data is scarce. We aimed to assess the effectiveness and predictive factors of effectiveness in a large Swedish cohort. Methods: Retrospective capture of data from local registries at five Swedish IBD centers. Clinical response and remission rates were assessed at three months after starting adalimumab treatment and patients were followed until colectomy or need for another biological. Bio-naive patients were compared to bio experienced patients. Factors associated with short term responses were assessed using logistic regression model. Failure on drug was assessed using a Cox proportional hazards regression model. Results: 118 patients (59 males, 59 females) with median age 34.4 years (IQR 27.0–51.4) were included. Median disease duration was 4.3 years (IQR 2.0–9.0) and follow-up 1.27 years (IQR 0.33–4.1). A clinical corticosteroid-free remission was achieved by 38/118 (32.2%) and response by 91/118 (77%) after three months. CRP >3 mg/l at baseline was predictive of short-term failure to reach corticosteroid-free remission. Factors associated with survival on the drug were male gender, CRP <3 mg/l and absence of primary sclerosing cholangitis. Patients >42 years of age at diagnosis were more likely to respond to adalimumab and remain on treatment compared to patients <20 years. Conclusions: An elevated CRP-level, primary sclerosing cholangitis and female gender were predictors of treatment failure. In contrast older age at diagnosis was a predictor of short-term clinical response and drug survival. Prior infliximab failure, regardless of cause, did not influence the outcome of adalimumab treatment.
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| 15. |
- Beccuti, A. G., et al.
(författare)
-
Hybrid control techniques for switched-mode DC-DC converters part II : The step-up topology
- 2007
-
Ingår i: 2007 American Control Conference, Vols 1-13. - 1424409888 - 9781424409884 ; , s. 5464-5471
-
Konferensbidrag (refereegranskat)abstract
- Several recent techniques from hybrid and optimal control are evaluated on a power electronics benchmark problem. The benchmark involves a number of practically interesting operating scenarios for a fixed-frequency step-up dc-dc converter. The specifications are defined such that good performance can only be obtained if the switched and nonlinear nature of the problem is respected during the design phase.
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| 16. |
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| 17. |
- Bergquist, Annika, et al.
(författare)
-
Increased risk of primary sclerosing cholangitis and ulcerative colitis in first-degree relatives of patients with primary sclerosing cholangitis
- 2008
-
Ingår i: Clinical Gastroenterology and Hepatology. - New York : Elsevier. - 1542-3565 .- 1542-7714. ; 6:8, s. 939-943
-
Tidskriftsartikel (refereegranskat)abstract
- Background & Aims: The importance of genetic factors for the development of primary sclerosing cholangitis (PSC) is incompletely understood. This study assessed the risk of PSC and inflammatory bowel disease (IBD) among first-degree relatives of patients with PSC, compared with the first-degree relatives of a cohort without PSC. Methods: Subjects from the national Swedish cohort of PSC patients (n = 678) were matched for date of birth, sex, and region to up to 10 subjects without a diagnosis of PSC (n = 6347). Linkage through general population registers identified first-degree relatives of subjects in both the PSC and comparison cohorts (n = 34,092). Diagnoses among first-degree relatives were identified by using the Inpatient Register. Results: The risk of cholangitis was statistically significantly increased in offspring, siblings, and parents of the PSC patient cohort, compared with relatives of the comparison cohort, with the hazard ratios and 95% confidence intervals, 11.5 (1.6–84.4), 11.1 (3.3–37.8), and 2.3 (0.9–6.1), respectively. The hazard ratios for ulcerative colitis (UC) among first-degree relatives of all PSC patients was 3.3 (2.3–4.9) and for Crohn's disease 1.4 (0.8–2.5). The risk of UC for relatives of PSC patients without IBD was also increased, 7.4 (2.9–18.9). Conclusions: First-degree relatives of patients with PSC run an increased risk of PSC, indicating the importance of genetic factors in the etiology of PSC. First-degree relatives of PSC patients without IBD are also at an increased risk of UC, which might indicate shared genetic susceptibility factors for PSC and UC.
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| 18. |
- Bjornsson, Einar, et al.
(författare)
-
Akut leversvikt - viktigt med snabb multidisciplinär handläggning
- 2007
-
Ingår i: Läkartidningen. - 0023-7205. ; 104:4, s. 210-213
-
Tidskriftsartikel (refereegranskat)abstract
- A recent study in Sweden on patients with acute liver failure (ALF) 1994-2003 demonstrated that the most common causes were paracetamol toxicity (42%) and idiosyncratic drug reactions (15%). In 11% of cases of ALF no definite etiology could be established. Among patients with paracetamol toxicity, the spontaneous survival without liver transplantation was 82% compared to 49% in patients with reactions to other drugs and 29% among the patients with indeterminate cause. Patients with ALF need a rapid and effective diagnostic work-up to detect the etiology as this often determines the outcome. In ALF it is of major importance to make an early contact with a transplant centre as the search for a suitable donor organ may take time in patients who are candidates for a liver transplantation. Patients with acute liver failure need a multidisciplinary care with co-operation between hepatologists, intensive care unit specialists and transplant surgeons.
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| 19. |
|
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| 20. |
|
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| 21. |
- Björnsson, Einar, et al.
(författare)
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Akut leversvikt - viktigt med snabb multidisciplinär handläggning : [Acute liver failure--rapid multidisciplinary management]
- 2007
-
Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 104:4, s. 210-213
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A recent study in Sweden on patients with acute liver failure (ALF) 1994-2003 demonstrated that the most common causes were paracetamol toxicity (42%) and idiosyncratic drug reactions (15%). In 11% of cases of ALF no definite etiology could be established. Among patients with paracetamol toxicity, the spontaneous survival without liver transplantation was 82% compared to 49% in patients with reactions to other drugs and 29% among the patients with indeterminate cause. Patients with ALF need a rapid and effective diagnostic work-up to detect the etiology as this often determines the outcome. In ALF it is of major importance to make an early contact with a transplant centre as the search for a suitable donor organ may take time in patients who are candidates for a liver transplantation. Patients with acute liver failure need a multidisciplinary care with co-operation between hepatologists, intensive care unit specialists and transplant surgeons.
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| 22. |
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| 23. |
- Danielsson Borssén, Åsa, et al.
(författare)
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Hepatocellular and extrahepatic cancer in patients with autoimmune hepatitis : a long-term follow-up study in 634 Swedish patients
- 2015
-
Ingår i: Scandinavian Journal of Gastroenterology. - : Informa Healthcare. - 0036-5521 .- 1502-7708. ; 50:2, s. 217-223
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives. Cirrhosis is a well-known risk factor for hepatocellular cancer, but the true risk in autoimmune hepatitis (AIH) is scarcely studied. Other cancers may arise after prolonged use of immune-modulating drugs. The aim of this study was to investigate the cancer risk in a large cohort of AIH patients.Material and methods. Six hundred and thirty-four Swedish patients in a well-defined cohort were matched to the Cause of Death Registry and the Cancer Registry. Standard incidence ratios were calculated by relating the incidences in the cohort to an age-matched material from the Swedish background population.Results. A higher overall incidence of malignancies than the background population was found, counting from the date of diagnosis (standard incidence ratio (SIR) 2.08, 95% CI 1.68-2.55). The highest risk was found for hepatocellular carcinoma (HCC). We found 10 cases (4.0%) in 248 patients with cirrhosis, which gives an incidence rate of 0.3%. Standard incidence ratio for developing hepatobiliary cancer was 54.55 (95% CI 19.92-99.99). HCC only occurred in cirrhotic patients. There was also an increased risk for non-melanoma skin cancer (SIR 9.87, 95% CI 6.26-14.81).Conclusion. A slightly enhanced risk for malignancies in general compared to the background population was found. The risk of hepatobiliary cancer was increased, but the annual risk over the observational period was well under the postulated 1.5% when surveillance in cirrhotic patients is considered to be cost-effective.
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| 24. |
- Danielsson Borssén, Åsa, 1977-, et al.
(författare)
-
Pregnancy and childbirth in women with autoimmune hepatitis is safe, even in compensated cirrhosis
- 2016
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Ingår i: Scandinavian Journal of Gastroenterology. - : Taylor & Francis. - 0036-5521 .- 1502-7708. ; 51:4, s. 479-485
-
Tidskriftsartikel (refereegranskat)abstract
- Introduction: Autoimmune hepatitis (AIH) is a liver disease that primarily affects women. Many become ill during childbearing age, and medication can be lifelong. Few studies exist on pregnancy outcome in women with AIH. Objectives: The aim was to assess the outcome of women with AIH and their children during pregnancy and postpartum.Materials and methods: Sixty-four women from a well-characterised cohort with AIH filled out a questionnaire with information about their disease, miscarriage/abortion, pregnancies and potential birth defects in 2012. In 2004, 106 women answered the same questionnaire and their results were analysed along with the new questionnaires. Results: One hundred and thirty-eight women have completed the questionnaire and 100 children have been born by 58 women. Fifty-seven women (41%) had cirrhosis. In 84% of the pregnancies, the AIH was stable or milder, 32% had an increase in activity postpartum. The proportion of preterm births (before week 38) was 22%, caesarean sections 17%, malformations 3%, and two children died. Twenty-three women with cirrhosis had children after diagnosis of cirrhosis but without more complications than for non-cirrhotic mothers. However, they did have a higher prevalence of caesarean sections. Conclusion: Pregnancy and childbirth in AIH appear to be safe for both child and mother, even in women with compensated liver cirrhosis.
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| 25. |
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| 26. |
- Elmberg, Maria, et al.
(författare)
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Increased Mortality Risk in Patients With Phenotypic Hereditary Hemochromatosis But Not in Their First-Degree Relatives
- 2009
-
Ingår i: Gastroenterology. - : Elsevier BV. - 0016-5085 .- 1528-0012. ; 137:4, s. 1301-1309
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND & AIMS: Hereditary hemochromatosis (HH) is an autosomal-recessive disorder characterized by iron overload. Relatives of HH patients were screened and those with HH-associated mutations and an increased iron load were identified. However, little is known about their mortality or strategies for their management. We assessed mortality among Swedish patients with HH and their first-degree relatives using health and census registers. METHODS: We performed a matched population-based cohort study of 3832 patients with HH and their 14,496 first-degree relatives using data collected from 1990 through 2007. Mortality data from these groups were compared with that of 38,969 population controls and their 143,349 first-degree relatives using Cox regression analyses. RESULTS: Patients identified on the basis of hospitalization with HH had an increased risk (relative risk [RR]) for death (RR, 2.45; 95% confidence interval [CI], 2.27-2.64; 857 deaths). Patients identified through other means had a mortality risk that was lower than those identified in the hospital but higher than controls (RR, 1.15; 95% CI, 1.00-1.33; 216 deaths). Their first-degree relatives had only a marginally increased mortality risk (RR, 1.05; 95% CI, 1.01-1.10); this RR was similar to that of patients' spouses (RR, 1.09; 95% CI, 0.86-1.38; 82 deaths). Patients with HH who also had a family history of HH did not have an increased mortality risk compared with other groups (RR, 1.05; 95% CI 0.67-1.62; 21 deaths). CONCLUSIONS: Patients with HH have a modestly increased mortality risk compared with controls. The mortality of relatives is increased marginally compared with controls, and is similar among biological and nonbiological relatives.
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| 27. |
- Fujioka, H., et al.
(författare)
-
Control synthesis for a class of PWM systems for robust tracking and H ∞ performance
- 2006
-
Ingår i: Proc IEEE Conf Decis Control. - 1424401712 - 9781424401710 ; , s. 4861-4866
-
Konferensbidrag (refereegranskat)abstract
- Robust control with robust tracking is considered for a class of pulse-width modulated systems (PWM) that appear, for example, in power electronics applications. The control objective is to regulate a high frequency ripple signal to robustly track a constant reference signal in an average sense. To achieve this goal, a new H∞ -control problem with integral action and averaged sampling is proposed. The design procedure is verified on a synchronous buck converter.
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| 28. |
- Fujioka, Hisaya, et al.
(författare)
-
LQ optimal control for a class of pulse width modulated systems
- 2007
-
Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 43:6, s. 1009-1020
-
Tidskriftsartikel (refereegranskat)abstract
- We consider linear quadratic optimal control for a class of pulse width modulated systems. The problem is motivated from a practical application-digital control of switching power converters. The control synthesis problem is posed based on a sampled data model of the original switching dynamics and a linear quadratic criterion that takes the intersampling behavior into account.
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| 29. |
- Fujioka, H., et al.
(författare)
-
LQ optimal control synthesis for a class of pulse modulated systems
- 2005
-
Konferensbidrag (refereegranskat)abstract
- We consider linear quadratic optimal control for a class of pulse-width-modulated systems. The problem is motivated from a practical application - digital control of switching power converters. The control synthesis problem is posed based on a sampled data model of the original switching dynamics and a linear quadratic criterion that takes the inter sampling behavior into account.
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| 30. |
- Fujioka, Hisaya, et al.
(författare)
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Robust tracking with H-infinity performance for PWM systems
- 2009
-
Ingår i: Automatica. - : Elsevier BV. - 0005-1098 .- 1873-2836. ; 45:8, s. 1808-1818
-
Tidskriftsartikel (refereegranskat)abstract
- Control synthesis for robust tracking is considered for a class of pulse-width modulated systems that appear, for example, in power electronics applications. The control objective is to regulate a high frequency ripple signal to robustly track a constant reference signal in an average sense. To achieve this goal, a new H-infinity control problem with integral action and average sampling is proposed. The solution of this problem involves a hybrid lifting framework which requires a careful elaboration in order to develop an algorithm that allows one to solve the design problem by the standard state space formulas for H-infinity control. The design procedure is verified on a synchronous buck converter.
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| 31. |
- Fujioka, H., et al.
(författare)
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Sampled-data H∞ control design for a class of PWM systems
- 2005
-
Ingår i: Proceedings of the 44th IEEE Conference on Decision and Control, and the European Control Conference, CDC-ECC '05. - 0780395689 - 9780780395688 - 0780395670 ; , s. 4499-4504
-
Konferensbidrag (refereegranskat)abstract
- Robust control of a class of switched dynamical systems is considered. The switching is controlled by pulse-width modulation (PWM). This idea is used, for example, in power electronics for power conversion. The class of systems considered includes digitally controlled power converters of many different types. The traditional approach to control design for power converters rely on an averaged model that ignores the high frequency behavior and the inherent time delay due to sampling. In contrast, the method presented here is based on a sampled-data model which takes the switched nature of the system into account. The sampled-data model is approximated by a linear quadratic model to which sampled-data H∞ theory can be extended. The approach is applied to a bidirectional boost converter which is subjected to a large load disturbance.
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| 32. |
- Juzenas, Simonas, et al.
(författare)
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Detailed transcriptional landscape of peripheral blood points to increased neutrophil activation in treatment-naïve inflammatory bowel disease
- 2022
-
Ingår i: Journal of Crohn's & Colitis. - : Oxford University Press. - 1873-9946 .- 1876-4479. ; 16:7, s. 1097-1109
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND AND AIMS: Inflammatory bowel disease (IBD) is a chronic relapsing disorder of the gastrointestinal tract, which generally manifests as Crohn's disease (CD) or ulcerative colitis (UC). These subtypes are heterogeneous in terms of disease location and histological features, while sharing common clinical presentation, genetic associations and thus, common immune regulatory pathways.METHODS: Using miRNA and mRNA coupled transcriptome profiling and systems biology approaches, we report a comprehensive analysis of blood transcriptomes from treatment-naïve (n=110) and treatment-exposed (n=177) IBD patients as well as symptomatic- (n=65) and healthy controls (n=95).RESULTS: Broadly, the peripheral blood transcriptomes of CD and UC patients were similar. However, there was an extensive gene deregulation in the blood of IBD patients, while only a slight deregulation in symptomatic controls, when compared with healthy controls. The deregulated mRNAs and miRNAs are mainly involved in the innate immunity and are especially enriched in neutrophil activation-related pathways. Oxidative phosphorylation and neutrophil activation-related modules were found to be differentially co-expressed among treatment-naïve IBD as compared to healthy controls. In the deregulated neutrophil activation-related co-expression module, the IL1B was identified as the central gene. The co-expression levels among IL1B and chemosensing receptor (CXCR1/2 and FPR1/2) genes were reduced in the blood of IBD patients when compared with healthy controls.CONCLUSIONS: Immune dysregulation seen in peripheral blood transcriptomes of treatment-naïve IBD patients is mainly driven by neutrophil activation.
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| 33. |
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| 34. |
- Lindgren, Stefan, et al.
(författare)
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Transitions between variant forms of primary biliary cirrhosis during long-term follow-up
- 2009
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Ingår i: EUROPEAN JOURNAL OF INTERNAL MEDICINE. - : Elsevier BV. - 0953-6205 .- 1879-0828. ; 20:4, s. 398-402
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Tidskriftsartikel (refereegranskat)abstract
- Background: Conditions exhibiting features of two different autoimmune liver diseases are designated overlap syndromes. Variant forms display some, but not all, characteristics of a distinct autoimmune liver disease. We describe transitions over time between variant forms of PBC, i.e. AMA-negative PBC, autoimmune hepatitis (AIH)-PBC overlap and autoimmune cholangitis (AIC) in a large cohort of PBC patients in Sweden. Methods: We retrieved all patients with variant forms of PBC in six university hospitals in Sweden, covering 60% of the Swedish population. The diagnosis of PBC and its variants was based on laboratory findings and compatible histological features. The revised autoimmune hepatitis scoring system proposed by the International Autoimmune Hepatitis Group was used to establish the diagnosis of AIH. Results: In a population of 800 patients with PBC, we identified 35 (5%) variant forms; 25 patients with AIH-PBC overlap, 8 with AIC and 2 with AMA-negative PBC at the time of our study. The initial diagnoses were PBC (3 patients), AIH (3), AIH-PBC overlap (16), AIC (8) and AMA-negative PBC with (1) or without (4) concomitant AIH. The median follow-up was 125 (41-360) months. Immunosuppression and ursodeoxycholic acid induced a complete or good regression of increased aminotransferases in about half of the patients who were given one or both of these treatments. Conclusions: Variant forms of PBC are seen in approximately 5% of PBC patients in Sweden. Transition between different forms may occur, emphasizing the value of repeat biopsies, but established overlapping AIH-PBC seems to be stable over time.
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| 35. |
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| 36. |
- Lundvall, Stefan, et al.
(författare)
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Djurens och växternas miljömål - åtgärdsprogram 2012-2016
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detta åtgärdsprogram gäller för åren 2012-2016 och omfattar miljökvalitetsmålen Ett rikt växt- och djurliv, Myllrande våtmarker, Levande skogar och Ett rikt odlingslandskap. Åtgärderna i programmet är konkreta insatser som ska bidra till att vi når miljökvalitetsmålen. Många av åtgärderna handlar om att informera markägare, lantbrukare, allmänhet med flera. Detta är en följd av att landskapsmålen är beroende av det sätt som vi sköter och brukar vår omgivning, och i det arbetet är alla som förvaltar ett stycke mark de viktigaste aktörerna. För varje enskild person är det dock svårt eller omöjligt att se helheten och här spelar myndigheter och övergripande organisationer en viktig roll som samordnare och förmedlare av information. På myndigheterna ligger också ansvaret att skydda och förvalta särskilt värdefulla områden, till exempel genom reservatsbildning. Flera av åtgärderna rör detta arbete. Programmet består av 38 stycken åtgärder varav 35 stycken är åtaganden och tre stycken är utmaningar. Åtaganden är åtgärder som aktörerna har åtagit sig att genomföra medan utmaningar är åtgärder som inte fått tillräcklig förankring hos aktörerna men ändå anses prioriterade. Bland de ansvariga aktörerna finns Länsstyrelsen som medverkar i 27 åtgärder, Skogsstyrelsen i 16, kommunerna i 10, LRF i 4, Jägareförbundet i 3, Södra i 2 och Hushållningssällskapet, Föreningen Smålands Flora, Smålands Turism, Naturskyddsföreningen och Jönköpings läns museum i en vardera. Där det varit möjligt har en huvudaktör utsetts, detta markeras genom en stjärna vid namnet på huvudaktören.
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| 37. |
- Lundvall, Stefan, et al.
(författare)
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Luftens och hälsans miljömål - Åtgärdsprogram 2010-2014
- 2010
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Frisk Luft, Giftfri miljö, Skyddande ozonskikt och Säker strålmiljö – alla är de miljömål av stor betydelse för vår hälsa och vårt välmående. För de fyra miljömålen finns både positiva och negativa trender idag. Till exempel minskar halterna av flera luftföroreningar samtidigt som ökad trafik gör att miljökvalitetsnormen för partiklar överskrids i centrala Jönköping och alltfler länsbor upplever problem från bilavgaser och trafikbuller. Fler människor i Sverige dör för tidigt på grund av luftföroreningar än på grund av bilolyckor. Internationella överenskommelser gör att framtiden ser hoppingivande ut för ozonskiktet. Samtidigt ser det mörkt ut för delmålet om att minska antalet nya fall av hudcancer till följd av UV-strålningen. Obetänksamma solvanor leder till att antalet hudcancerfall i länet fortsätter att öka. Många miljögifter har förbjudits och halterna minskar i natur och människor samtidigt som nya kemikalier tillkommit utan att vi ännu vet konsekvenserna. Som alla förstår har miljöarbetet gjort stor nytta historiskt, men det finns mycket kvar att göra. Därför behövs fortsatt arbete med åtgärdsprogram för miljökvalitetsmålen. Åtgärder för Frisk luft hänger ofta ihop med klimatfrågan. Därför har många av åtgärderna i programmet betydelse för klimatet. Ett bredare och mer långsiktigt grepp om klimatarbetet kommer att tas i den Klimat- och energistrategi som just nu håller på att tas fram. Länsstyrelsen vill tacka alla som deltagit i arbetet med att ta fram åtgärdsprogrammet. Det har skett i en positiv anda med många medverkande från kommuner, näringsliv och andra myndigheter. Detta åtgärdsprogram löper över åren 2010-2014 och omfattar miljökvalitetsmålen Frisk luft, Giftfri miljö, Skyddande ozonskikt och Säker strålmiljö samt delmål tre och fyra under Bara naturlig försurning. Programmet syftar till att miljömålen för Jönköpings län ska uppnås. Länets miljömål följer samma struktur som de nationella målen och utgör länets bidrag till att de nationella målen ska uppnås. Åtgärder för att skapa Frisk luft berör huvudsakligen energi- och trafikområdena och därför finns en stark koppling till klimatfrågan. De flesta åtgärderna under Frisk luft har prioriterats för att de också bidrar till miljökvalitetsmålet Begränsad klimatpåverkan. Ett helhetsgrepp på klimatarbetet kommer att tas i Klimat- och energistrategin som tas fram år 2009-2010. Åtgärderna i detta program har delats in i Åtaganden och Utmaningar. Under rubriken Åtaganden finns åtgärder där berörda aktörer åtagit sig att genomföra dem (för de åtgärder där kommunerna är ansvariga aktörer gäller att minst sju kommuner har åtagit sig att medverka).
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| 38. |
- Mariethoz, Sebastien, et al.
(författare)
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Comparison of Hybrid Control Techniques for Buck and Boost DC-DC Converters
- 2010
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Ingår i: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 18:5, s. 1126-1145
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Tidskriftsartikel (refereegranskat)abstract
- Five recent techniques from hybrid and optimal control are evaluated on two power electronics benchmark problems. The benchmarks involve a number of practically interesting operating scenarios for fixed-frequency synchronous dc-dc converters. The specifications are defined such that good performance can only be obtained if the switched and nonlinear nature of the problem is accounted for during the design phase. A nonlinear action is featured in all methods either intrinsically or as external logic. The designs are evaluated and compared on the same experimental platform. Experiments show that the proposed methods display high performances, while respecting circuit constraints, thus protecting the semiconductor devices. Moreover, the complexity of the controllers is compatible with the high-frequency requirements of the considered application.
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| 39. |
- Mesterton, Johan, et al.
(författare)
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Resource Use and Societal Costs for Crohn's Disease in Sweden
- 2009
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Ingår i: Inflammatory Bowel Diseases. - : Oxford University Press (OUP). - 1536-4844 .- 1078-0998. ; 15:12, s. 1882-1890
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Tidskriftsartikel (refereegranskat)abstract
- Background: The usual onset of Crohn's disease (CD) is between 15 and 30 years of age, thus affecting people during their most economically productive period in life. Methods: This study intended to estimate societal costs and health-related quality of life (HRQoL) in Swedish patients in different stages of CD. Cross-sectional data on disease activity (measured with the Harvey-Bradshaw Index [HBI]), direct medical resource use, work productivity, and HRQoL (assessed using the 15D instrument) were collected for 420 patients by questionnaires to patients, to the treating physician, and from medical records. Based on HBI, current treatment, and response to treatment, patients were classified into the following disease states: Remission, Response, Active, Refractory, and Surgery. Results: The average 4-week cost per patient in 2007 was estimated at (sic)721 (USD 988), of which 64% was due to lost productivity. The total 4-week cost of care was (sic)255 (USD 349) in Remission, (sic)831 (USD 1138) in Response, (sic)891 (USD 1220) in Active, (sic)1360 (USD 1864) in Refractory, and (sic)16984 (USD 23269) in Surgery. HBI was the most important predictor of costs of care-a 1-point increase in HBI increased total costs by 25% (P < 0.001). HRQoL differed between the disease states: 0.92 in Remission, 0.90 in Response, 0.82 in Active, 0.81 in Refractory, and 0.77 in Surgery. Conclusions: Patients in remission have the lowest costs and the highest HRQoL. Patients responding to treatment have lower costs of care than patients with high disease activity who are not treated or do not respond to treatment:. Thus, total costs of care might be reduced by efficient treatment.
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| 40. |
- Olsson, Rolf, et al.
(författare)
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High prevalence of small duct primary sclerosing cholangitis among patients with overlapping autoimmune hepatitis and primary sclerosing cholangitis
- 2009
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Ingår i: EUROPEAN JOURNAL OF INTERNAL MEDICINE. - : Elsevier BV. - 0953-6205 .- 1879-0828. ; 20:2, s. 190-196
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Tidskriftsartikel (refereegranskat)abstract
- Background: Overlap syndrome is a term used for overlapping features of autoimmune hepatitis and primary sclerosing cholangitis or primary biliary cirrhosis and for autoimmune cholangitis. We describe a high prevalence of small duct primary sclerosing cholangitis among patients with overlapping autoimmune hepatitis and primary sclerosing cholangitis. Methods: We sought to retrieve all patients with overlap syndrome between primary sclerosing cholangitis and autoimmune hepatitis in six university hospitals in Sweden. The revised autoimmune hepatitis scoring system proposed by the International Autoimmune Hepatitis Group was used to establish the diagnosis autoimmune hepatitis. Endoscopic retrograde cholangiography and/or magnetic resonance cholangiography were used to separate the primary sclerosing cholangitis cases diagnosed through liver biopsy into small and large primary sclerosing cholangitis. A histologocial diagnosis compatible with both autoimmune hepatitis and primary sclerosing cholangitis was required for inclusion. Results: 26 patients fulfilled our criteria for histological overlap of autoimmune hepatitis and primary sclerosing cholangitis, 7 (27%) of which had small duct primary sclerosing cholangitis. The reliability of the diagnosis small duct primary sclerosing cholangitis was supported by a very close similarity between small and large duct primary sclerosing cholangitis patients in clinical and laboratory data, and by a poor response to immunosuppressive therapy in the small duct primary sclerosing cholangitis patients. Patients with large duct overlap syndrome had a good response to immunosuppressive therapy. In both groups, our limited experience from ursodeoxycholic acid was largely poor. Conclusions: Small duct primary sclerosing cholangitis is prevalent in the overlap syndrome between autoimmune hepatitis and primary sclerosing cholangitis.
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| 41. |
- Pagoldh, Maria, et al.
(författare)
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Faecal analysis and plasma complement factor 3c levels at admission for an acute attack of ulcerative colitis are predictive of the need for colectomy
- 2014
-
Ingår i: European Journal of Gastroenterology and Hepathology. - : Ovid Technologies (Wolters Kluwer Health). - 0954-691X .- 1473-5687. ; 26:3, s. 295-300
-
Tidskriftsartikel (refereegranskat)abstract
- BackgroundUlcerative colitis is a chronic inflammation limited to the large bowel. Early identification of reliable predictive markers addressing the risk of need for colectomy in a severe attack of ulcerative colitis is of crucial importance.ObjectiveTo evaluate faecal characteristics and peripheral blood tests as predictive markers for subsequent risk of colectomy in a severe attack of ulcerative colitis.MethodsThis was an observational study. Samples were collected in a cohort of 18 patients with a severe attack of ulcerative colitis. A panel of selected variables was evaluated (faecal characteristics, peripheral blood samples including complement factor 3c, circulating cytokines and antisecretory factor) for ability to predict colectomy. The patients were observed for up to 58 months (median 37.5, range 0.5-58 months) and allocated to one of two groups depending on the clinical outcome on the basis of the need for colectomy.ResultsSeven patients underwent colectomy. The present study showed a positive correlation between increased bowel movements (P=0.01), faecal weight/bowel movement (P=0.03) and complement factor 3c levels (P=0.01) and a need for later colectomy. None of the other laboratory markers investigated were shown to be predictive of risk for later colectomy.ConclusionEarly faecal analysis and measurement of complement factor 3c may be useful as predictive markers of the need for colectomy related to a severe attack of ulcerative colitis.
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| 42. |
- Tysk, Curt, et al.
(författare)
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Handläggning av svårt skov av ulcerös kolit
- 2009
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 106:45, s. 2994-2998
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Tidskriftsartikel (refereegranskat)abstract
- Patienter med svårt skov av ulcerös kolit bör vårdas på sjukhus och handläggas av gastroenterolog och kolorektal kirurg i nära samarbete.Skovets svårighetsgrad kan underskattas, varför noggrann bedömning av inflammationens utbredning och svårighetsgrad enligt validerade kriterier är viktigt.Intravenös behandling med kortikosteroider är en av hörnstenarna i den akuta behandlingen.Patienter som inte förbättras på denna behandling, bör erbjudas medicinsk »rescue-behandling« eller kolektomi.Infliximab har visats vara en effektiv rescue-behandling och kan minska behovet av kolektomi inom de första 3 månaderna och upp till 3 år.
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| 43. |
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| 44. |
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| 45. |
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| 46. |
- Werner, Mårten, et al.
(författare)
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Autoimmune hepatitis among fertile women : strategies during pregnancy and breastfeeding?
- 2007
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Ingår i: Scandinavian Journal of Gastroenterology. - : Informa UK Limited. - 0036-5521 .- 1502-7708. ; 42:8, s. 986-991
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Tidskriftsartikel (refereegranskat)abstract
- Objective. In published studies there is a lack of data about the risks, management and how women with autoimmune hepatitis (AIH) decide on and are advised about pregnancy. The aim of this study was to investigate how women with AIH consider pregnancies, are advised and pharmacologically treated, as well as the outcome. Material and methods. A questionnaire was mailed to 128 women with AIH diagnosed during their fertile period and data from the Swedish National Birth Register was also used for matched controls. Results. There was an 83% response rate to the questionnaires. Sixty-three pregnancies were reported by 35 women. 48% did not consult their doctors before getting pregnant. More than half of the women reduced or stopped the immune suppression during pregnancy or breastfeeding. Some women were advised to abstain from pregnancy or even to have an abortion. Caesarean sections were performed more frequently in the AIH group (16% compared with 6.5% in the control group p<0.01).There were no significant differences in the number of stillborn infants or infants with malformations. However, 30% of the patients experienced flare-up after delivery. Conclusions. In general, the outcome of pregnancy in women with AIH seems to be good. Current pharmacological treatment appears to be safe, including azathioprine during pregnancy and lactation. After delivery an active preparedness to increase pharmacotherapy should be considered.
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| 47. |
- Werner, Marten, et al.
(författare)
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Characteristics and long-term outcome of patients with autoimmune hepatitis related to the initial treatment response
- 2010
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Ingår i: SCANDINAVIAN JOURNAL OF GASTROENTEROLOGY. - : Taylor and Francis. - 0036-5521 .- 1502-7708. ; 45:4, s. 457-467
-
Tidskriftsartikel (refereegranskat)abstract
- Objectives. Autoimmune hepatitis (AIH) is a liver disease which, if untreated, may lead to liver cirrhosis and hepatic failure. Limited data exist regarding factors predicting the long-term outcome. The aims of this study were to investigate symptoms at presentation, prognostic features, management and treatment in relation to long-term outcome of AIH. Material and methods. A cohort of 473 Swedish patients with AIH was characterized regarding initial symptoms and signs, factors predicting death and future need for liver transplantation. Survival and causes of death were retrieved from Swedish national registers. Results. At diagnosis, fatigue was a predominant symptom (69%), 47% of the patients were jaundiced and 30% had liver cirrhosis. Another 10% developed cirrhosis during follow-up. Markedly elevated alanine aminotransferase levels at presentation were correlated with a better outcome. A high international normalized ratio (INR) at diagnosis was the only risk factor predicting a need for later liver transplantation. Histological cirrhosis, decompensation and non-response to initial treatment were all factors that correlated with a worse outcome. Overall life expectancy was generally favourable. However, most deaths were liver-related, e.g. liver failure, shock and gastrointestinal bleeding. Conclusions. Cirrhosis at diagnosis, a non-response to initial immune-suppressive treatment or elevated INR values were associated with worse outcome and a need for later liver transplantation. In contrast, an acute hepatitis-like onset with intact synthetic capacity indicated a good response to treatment and favourable long-term prognosis. Lifetime maintenance therapy is most often required.
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| 48. |
- Werner, Mårten, et al.
(författare)
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Hepatic and extrahepatic malignancies in autoimmune hepatitis. A long-term follow-up in 473 Swedish patients
- 2009
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Ingår i: Journal of Hepatology. - : Elsevier BV. - 0168-8278 .- 1600-0641. ; 50:2, s. 388-393
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Tidskriftsartikel (refereegranskat)abstract
- Background/Aims: Autoimmune Hepatitis (AIH) is a liver disease which may lead to liver cirrhosis. Cirrhosis is a well-known risk factor for hepatocellular cancer. Lymphoma is a disease, where immune modulating drugs as well as the autoimmune disease itself may contribute to the elevated risk. The aim was to investigate the risks of malignancies in a large cohort of AIH patients. Methods: Four hundred and seventy-three patients with AIH were matched to the Swedish national cancer register as well as to the death cause register. Results: We found an overall higher risk of malignancies in the cohort of A I H patients from the date of diagnosis with a SIR of 1.51 (95% CI 1.10-2.03). SIR in the subpopulation of well defined catchment areas and complete case finding was 23.28 (95% CI 7.5-54.34) for HCC. Lymphomas were found a SIR of 13.09 (95% CI 4.22-30.56). Conclusions: There was an overall increased risk of malignancies in a cohort of AIH patients, which manly was caused by hepatobiliary cancers. However, the true risk of HCC in an AIH cirrhotic cohort has yet to be investigated. A significantly higher risk of lymphomas was also found, but no clear cut association to the use of immune modulators.
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