| 1. |
- Andersson, Lars-Göran, et al.
(författare)
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Thallium-201 Myocardial Imaging at Rest in Male Orienteers and Other Endurance Athletes
- 2001
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 106:1, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- During the period 1979 to 1992, 16 sudden unexpected cardiac deaths were known to have occurred in young Swedish orienteers. Autopsy indicated myocarditis to be the most frequent finding, most often combined with extensive myocardial fibrosis. The aim of the present investigation was to explore whether young male orienteers show a higher frequency than other young elite endurance athletes (controls) in the occurrence of Thallium-201 myocardial perfusion defects at rest, suggestive of fibrosis evoked by myocarditis. Thallium-201 perfusion abnormalities at rest were more frequently found in the controls than in the orienteers (26% vs. 12%, p=0.03). Uneven Tl-201 perfusion was associated with left ventricular mass (r=0.32, r=0.24, p<0.01, p=0.02) and body weight (r=0.30, r=0.31, p<0.01, p=0.03) in orienteers and controls, respectively. Echocardiographic left ventricular wall motion abnormalities were found in 11 athletes (9 orienteers and 2 controls) but only two displayed an abnormal Thallium-201 perfusion scan at rest. Perfusion abnormalities at rest did not occur more frequently in the orienteers but were commonly found in both groups of apparently healthy athletes making it futile to discern abnormals from normals. Thallium-201 perfusion aberrations were not associated with left ventricular wall motion abnormalities obtained by echocardiography.
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| 2. |
- Damm, S., et al.
(författare)
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Wall motion abnormalities in male elite orienteers are aggravated by exercise
- 1999
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Ingår i: Clinical Physiology. - : Wiley. - 0144-5979 .- 1365-2281. ; 19:2, s. 121-126
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Tidskriftsartikel (refereegranskat)abstract
- During the period 1979-92, 16 (15 men and one woman) sudden unexpected cardiac deaths occurred among young Swedish orienteers. This finding indicated a sharp increase in the death rate of orienteers, and necropsy demonstrated that myocarditis was a common histopathological finding. Therefore, an extensive non-invasive cardiac investigation was performed. A total of 59 male élite orienteers (mean age 23 years) and 36 cross-country skiers and middle-distance runners (mean age 22 years), serving as controls, were examined by both echocardiography at rest and radionuclide ventriculography at rest and during exercise. Wall motion abnormalities were found in eight orienteers using echocardiography. The purpose of this study was to examine whether the group of orienteers with wall motion abnormalities found using echocardiography had a smaller increase in ejection fraction from rest to exercise using radionuclide ventriculography than the rest of the orienteers and the controls, indicating an aggravation of the wall motion abnormalities during exercise. There were no significant differences in the ejection fraction at rest between the groups. In the orienteers with wall motion abnormalities (group 1), 62% (five out of eight) had less than a 0.05 unit increase in left ventricular ejection fraction compared with 27% (14 out of 51) of the remaining orienteers (group 2) and 19% (7 out of 36) of the controls (group 3). A comparison of athletes in group 1 with those in groups 2 and 3 combined revealed a statistically significant difference (P < 0.05). The divergent response in left ventricular ejection fraction during exercise suggests an aggravation of the wall motion abnormalities with exercise. Both the echocardiographic and the radionuclide ventriculographic findings indicate that the orienteers in group 1 had concealed left ventricular damage.
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| 3. |
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| 4. |
- Johansson, Fredrik
(författare)
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Evaluating the performance of TEWA systems
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is in military engagements the task of the air defense to protect valuable assets such as air bases from being destroyed by hostile aircrafts and missiles. In order to fulfill this mission, the defenders are equipped with sensors and firing units. To infer whether a target is hostile and threatening or not is far from a trivial task. This is dealt with in a threat evaluation process, in which the targets are ranked based upon their estimated level of threat posed to the defended assets. Once the degree of threat has been estimated, the problem of weapon allocation comes into the picture. Given that a number of threatening targets have been identified, the defenders need to decide on whether any firing units shall be allocated to the targets, and if so, which firing unit to engage which target. To complicate matters, the outcomes of such engagements are usually stochastic. Moreover, there are often tight time constraints on how fast the threat evaluation and weapon allocation processes need to be executed. There are already today a large number of threat evaluation and weapon allocation (TEWA) systems in use, i.e. decision support systems aiding military decision makers with the threat evaluation and weapon allocation processes. However, despite the critical role of such systems, it is not clear how to evaluate the performance of the systems and their algorithms. Hence, the work in thesis is focused on the development and evaluation of TEWA systems, and the algorithms for threat evaluation and weapon allocation being part of such systems. A number of algorithms for threat evaluation and static weapon allocation are suggested and implemented, and testbeds for facilitating the evaluation of these are developed. Experimental results show that the use of particle swarm optimization is suitable for real-time target-based weapon allocation in situations involving up to approximately ten targets and ten firing units, while it for larger problem sizes gives better results to make use of an enhanced greedy maximum marginal return algorithm, or a genetic algorithm seeded with the solution returned by the greedy algorithm.
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| 5. |
- Niklasson, Annika, 1977, et al.
(författare)
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Air Pollutant Concentrations and Atmospheric Corrosion of Organ Pipes in European Church Environments
- 2008
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Ingår i: Studies in Conservation. - 0039-3630 .- 2047-0584. ; 53:1, s. 24-40
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Tidskriftsartikel (refereegranskat)abstract
- Abstract: The atmospheric environment inside and outside historical organs in several European regions is reported. In each region, comparisons were made between an instrument suffering organ pipe corrosion and an organ without corrosion problems. Concentrations of acetic acid (ethanoic acid), formic acid (methanoic acid), acetaldehyde (ethanal), formaldehyde (methanal) and other volatile organic compounds in the organ environment were determined using active sampling. Temperature and relative humidity were recorded. In addition, polished metal samples that mimic the material used in the historical organ pipes have been exposed in the organ wind systems for up to 22 months. High concentrations of acetic acid and formic acid vapours are present in the wind system of the corroded organs. Acetaldehyde and formaldehyde are also present in smaller amounts. The main source of acetic acid is the wood from which the wind system is built. In contrast, formic acid is generated in the chruch environment outside the wind system. The results show that the two organic acids play an important role in the atmospheric corrosion of organ pipes. It is suggested that the corrosion of lead pipes in historical organs can be effectively reduced by removing the sources of gaseous acetic acid and formic acid in the wind system and in the chruch environment.
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| 6. |
- Steffenburg-Nordenström, Joachim, 1962-
(författare)
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Process chain simulation of forming, welding and heat treatment of Alloy 718
- 2017
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Manufacturing of aero engine components requires attention to residual stress and final shape of the product in order to meet high quality product standards.This sets very high demands on involved manufacturing steps to meet design requirements. Simulation of manufacturing processes can therefore be animportant tool to contribute to quality assurance.The focus in this work is on simulation of a manufacturing process chain comprising of sheet metal forming, welding and a stress relief heat treatment.Simulation of sheet metal forming can be used to design a forming tool design that accounts for the material behaviour, e.g. spring back, and avoid problems such as wrinkling, thinning and cracking. Moreover, the simulation can also show how the material is stretched and work hardened. The residual stresses after forming may be of local character or global depending on the shape that is formed. However, the heat affected zone due to welding is located near the weld.The weld also causes large residual stresses with the major component along the weld. It is found that the magnitude of the residual stresses after welding is affected by remaining stresses from the previous sheet metal forming. The final stress relieve treatment will relax these residual stresses caused by e.g. forming and welding. However, this causes additional deformations.The main focus of this study is on how a manufacturing process step affects the subsequent step when manufacturing a component of the nickel-based super alloy 718. The chosen route and geometry is a simplified leading edge of an exhaust case guide vane. The simulations were validated versus experiments. The computed deformations were compared with measurements after each manufacturing step. The overall agreement between experiments and measurement was good. However, not sufficiently accurate considering the required tolerance of the component. It was found from simulations that the residual stresses after each process affects the subsequent step. After a complete manufacturing process chain which ends with a stress relief heat treatment the residual stresses were not negligible. VIII Special experiments were performed for studying the stress relief in order to understand how the stresses evolve through the heat treatment cycle during relaxation. It was found that the stresses were reduced already during the beginning of the heating up sequence due to decreasing Young´s modulus and yield stress with increasing temperature. Relaxation due to creep starts when a certain temperature was reached which gave a permanent stress relief.
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| 7. |
- Albertsson-Wikland, Kerstin, 1947, et al.
(författare)
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A new Swedish reference for total and prepubertal height.
- 2020
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Ingår i: Acta paediatrica (Oslo, Norway : 1992). - : Wiley. - 1651-2227 .- 0803-5253. ; 109:4, s. 754-763
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to develop up-to-date references with standard deviation scores (SDS) for prepubertal and total height.Longitudinal length/height measures from 1572 healthy children (51.5% boys) born at term in 1989-1991 to non-smoking mothers and Nordic parents were obtained from the GrowUp 1990 Gothenburg cohort. A total height SDS reference from birth to adult height was constructed from Quadratic-Exponential-Pubertal-Stop (QEPS) function estimated heights based on individual growth curves. A prepubertal height SDS reference, showing growth trajectory in the absence of puberty, was constructed using the QE functions.The total height reference showed taller prepubertal mean heights (for boys 1-2cm; for girls 0.5-1.0cm) with a narrower normal within ±2SDS range versus the GrowUp 1974 Gothenburg reference. Adult height was increased by +0.9cm for females (168.6cm) and by +1.6cm for males (182.0cm). Height in children growing at -2SDS (the cutoff used for referrals) differed up to 2cm versus the GrowUp 1974 Gothenburg reference, 3cm versus Swedish 1981 references and World Health Organization (WHO) 0-5 years standard, and 6-8cm versus the WHO 5-19 years reference.Up-to-date total and prepubertal height references offer promise of improved growth monitoring compared with the references used in Sweden today.
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| 8. |
- Albertsson-Wikland, Kerstin, 1947, et al.
(författare)
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A new type of pubertal height reference based on growth aligned for onset of pubertal growth
- 2020
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Ingår i: Journal of Pediatric Endocrinology & Metabolism. - : Walter de Gruyter GmbH. - 0334-018X .- 2191-0251. ; 33:9, s. 1173-1182
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Growth references of today traditionally describe growth in relation to chronological age. Despite the broad variation in age of pubertal maturation, references related to biological age are lacking. To fill this knowledge gap, we aimed to develop a new type of pubertal height reference for improved growth evaluation during puberty, considering individual variation in pubertal timing. Methods: Longitudinal length/height measures were obtained from birth to adult height in 1,572 healthy Swedish children (763 girls) born at term similar to 1990 to nonsmoking mothers and Nordic parents, a subgroup of GrowUp(1990) Gothenburg cohort. A total height reference was constructed from Quadratic-Exponential-Puberty-Stop (QEPS)-function-estimated heights from individual height curves that had been aligned for time/age at onset of pubertal growth (5% of P-function growth). References that separated growth into specific pubertal height(SDS ) P-function growth) and basic height(SDS) (QES-function growth) were also generated. Results: References (cm and SDS) are presented for total height, and height subdivided into that specific to puberty and to basic growth arising independently of puberty. The usefulness of the new pubertal growth reference was explored by identifying differences in the underlying growth functions that translate into differences in pubertal height gain for children of varying body mass, height, and with different pubertal timings. Conclusions: A new type of height reference allowing alignment of individual growth curves, based on the timing of the pubertal growth spurt was developed using QEPS-model functions. This represents a paradigm shift in pubertal growth research and growth monitoring during the adolescent period.
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| 9. |
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| 10. |
- Albertsson-Wikland, Kerstin, et al.
(författare)
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Mortality Is Not Increased in Recombinant Human Growth Hormone-treated Patients When Adjusting for Birth Characteristics
- 2016
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : ENDOCRINE SOC. - 0021-972X .- 1945-7197. ; 101:5, s. 2149-2159
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Tidskriftsartikel (refereegranskat)abstract
- Objective: This study aimed to investigate whether reported high mortality in childhood recombinant human GH (rhGH)-treated patients was related to birth-characteristics and/or rhGH treatment. Design and Setting: We sought to develop a mortality model of the Swedish general population born between 1973 and 2010, using continuous-hazard functions adjusting for birth characteristics, sex, age intervals, and calendar year to estimate standardized mortality ratio (SMR) and to apply this model to assess expected deaths in Swedish rhGH-treated patients with idiopathic isolated GH deficiency (IGHD), idiopathic short stature (155) or born small for gestational age (SGA). Participants:The general population: Swedish Medical Birth Register (1973-2010: 1 880 668 males; 1 781 131 females) and Cause of Death Register (1985-2010). Intervention Population: Three thousand eight hundred forty-seven patients starting rhGH treatment between 1985 and 2010 and followed in the National GH Register and/or in rhGH trials diagnosed with IGHD (n = 1890), ISS (n = 975), or SGA (n=982). Main Outcome Measures: Death. Results: Using conventional models adjusting for age, sex, and calendar-year, the SMR was 1.43 (95% confidence interval, 0.89-2.19), P = .14, observed/expected deaths 21/14.68. The rhGH population differed (P amp;lt; .001) from the general population regarding birth weight, birth length, and congenital malformations. Application of an Advanced Model: When applying the developed mortality model of the general population, the ratio of observed/expected deaths in rhGH-treated patients was 21/21.99; SMR = 0.955 (0.591-1.456)P = .95. Model Comparison: Expected number of deaths were 14.68 (14.35-14.96) using the conventional model, and 21.99 (21.24-22.81) using the advanced model, P amp;lt; .001, which had at all ages a higher gradient of risk per SD of the model, 24% (range, 18-42%; P amp;lt; .001). Conclusions: Compared with the general Swedish population, the ratio of observed/expected deaths (21/21.99) was not increased in childhood rhGH-treated IGHD, ISS, and SGA patients when applying an advanced sex-specific mortality model adjusting for birth characteristics.
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