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| 2. |
- Dahlbäck, Charlotte, et al.
(författare)
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Abnormal ductus venosus pulsatility index in the absence of concurrent umbilical venous pulsations does not indicate worsening fetal condition.
- 2013
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Ingår i: Ultrasound in Obstetrics & Gynecology. - : Wiley. - 1469-0705 .- 0960-7692. ; 42:3, s. 322-328
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: Recordings of blood flow velocity waveform in the ductus venosus (DV) and the umbilical vein (UV) are routinely used in order to predict the fetal condition in high-risk pregnancies. This study investigates the relationship between pathological blood flow in the two vessels and perinatal outcome. METHODS: High-risk pregnancies (n=11865) admitted during 1993-2011 for blood flow examinations, including recordings of DV pulsatility index for veins (PIV) and UV pulsations, were included. The results were related to perinatal outcome, using the last Doppler examination prior to delivery in analysis. RESULTS: Abnormal DV PIV was observed in 3,96%, intra-abdominal UV-pulsations in 1,3% and pulsations in the cord in 0,7% of the cases. As expected, the rate of UV-pulsations increased with increasing DV PIV z-score. Fetuses with a pathological DV PIV, but without UV pulsations showed no signs of compromise. This was also true for cases with a DV PIV >4 SD above the mean (53.7 % had a steady flow in the UV). In contrast, the occurrence of UV-pulsations seems to be an indicator of fetal compromise regardless of level of DV PIV. CONCLUSIONS: Abnormal fetal venous blood velocity is related to adverse outcome of high-risk pregnancies. However, abnormal DV PIV is not an indicator of fetal compromise unless UV-pulsations are concurrently present and should be regarded as an artifact and not an indication for emergency delivery.
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| 3. |
- Garcia Wernersson, Joakim, et al.
(författare)
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Non-destructive density measurements of pharmaceutical products by THz imaging
- 2016
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Ingår i: International Conference on Infrared, Millimeter, and Terahertz Waves, IRMMW-THz. - 2162-2027 .- 2162-2035. - 9781467384858 ; 2016-November, s. Art. no 7758615-
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Konferensbidrag (refereegranskat)abstract
- In this paper, measurements with a THz imaging system at 346 GHz together with electromagnetic simulations have demonstrated the capability of THz sensing for the non-destructive density determination of intermediate products in the pharmaceutical industry. The results confirm the ability of THz imaging to detect density changes in pharmaceutical samples by measuring the phase variation of the wave transmitted through the sample.
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| 5. |
- Ljunggren, Stefan, 1988-
(författare)
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Lipoproteomics : Environmental and Genetic Factors Affecting High-Density Lipoprotein (HDL)
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Lipoprotein particles act as lipid transporters in the blood stream, and measuring cholesterol content in specific subclasses of lipoprotein particles has long been, and still is, a frequently used tool to estimate the risk of cardiovascular disease (CVD). High-density lipoprotein (HDL) is a subclass of lipoproteins often regarded as providing protection against CVD via several functions including reverse cholesterol transport and anti-inflammatory capacities. However, the precise relationship between HDL cholesterol levels and health outcome is still unclear. Lately, new approaches to study HDL composition and function have therefore become more important.HDL function is to a large extent dependent on its proteome, containing more than 100 proteins. Investigating the proteome in individuals with altered gene expression for HDL-associated proteins or with known exposure to environmental contaminants may reveal new insights into how HDL metabolism is affected by various factors. This is of interest in order to better understand the role of HDL in CVD.Papers I and II focus on two different mutations in a structural HDL protein, apolipoprotein A-I (L202P and K131del), and one mutation in the scavenger receptor class B-1 (P297S), which is involved in selective lipid uptake of cholesterol mainly into hepatocytes and adrenal cells. The HDL proteome was analyzed using two-dimensional gel electrophoresis and mass spectrometry. The L202P mutation was identified in HDL of the heterozygote carriers together with a significant decrease of apolipoprotein E and increased zinc-alpha-2-glycoprotein. By contrast, the second apolipoprotein AI mutation (K131del) was associated with significantly elevated alpha-1-antitrypsin and transthyretin levels. Protein analyses of the scavenger receptor class B1 P297S heterozygotes showed a significant increase in HDL apoL-1 along with increased free apoE. The carriers showed no difference in antioxidative capability but a significant increase in apoA-I methionine oxidation.Papers III and IV focus on persistent organic pollutants that may influence HDL composition and function. These compounds accumulate in humans, and exposure has been linked to an increased risk of CVD. To provide a better understanding of the HDL system in relation to pollutants, a population living in a contaminated area was studied. Persistent organic pollutants in isolated HDL were quantified using high-resolution gas chromatography mass spectrometry and significantly increased levels were found in individuals with CVD as compared to healthy controls. Furthermore, there was a significant negative association between the pollutants and paraoxonase-1 anti-oxidant activity. Studying the proteome with nano-liquid chromatography tandem mass spectrometry led to the identification of 118 proteins in HDL, of which ten were significantly associated with the persistent organic pollutants.In summary, the present studies demonstrate protein pattern alterations in HDL associated with inherited genetic variants or pollutant exposure. The studies also provide a set of methods that are useful tools to further comprehend the complexity of lipoprotein metabolism and function. The results are important in order to improve our understanding of HDL in CVD and to explain an increased risk of CVD associated with exposure to organic pollutants.
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| 6. |
- Lundström, Ludvig, et al.
(författare)
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Influence on the stability of generator rotors due to radial and tangential magnetic pull force
- 2007
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Ingår i: IET Electric Power Applications. - : Institution of Engineering and Technology (IET). - 1751-8660 .- 1751-8679. ; 1:1, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Forces due to nonuniform airgaps in rotating electrical machines have been a researchtopic for over 100 years. However, most research in the area of rotating electrical machines hasbeen performed on motors. Large forces in hydropower generators can lead to expensive damageand failures. Therefore, it is of interest to calculate the forces that arise in a large synchronousgenerator with an eccentric rotor and study the influence these forces have on the stability of thegenerator rotor. A 74 MVA synchronous hydropower generator was simulated with an eccentricrotor, using a time-stepping finite-element technique. The forces were calculated using Coulomb’svirtual-work method and simulations were performed for no-load and load cases. The resultingforce was found to be reduced significantly when a damper winding was taken into account. Aninteresting effect of the rotor damper winding was that it reduced the eccentricity force andintroduced a force component perpendicular to the direction of eccentricity. The results from thefinite-element simulations were used to determine how the forces affect the stability of the generatorrotor. Damped natural eigenfrequencies and damping ratio for load and no-load conditions arepresented. When applying the forces computed in the time-dependent model, the damped naturaleigenfrequencies were found to increase and the stability of the generator rotor was found to bereduced compared with when the forces were computed in a stationary model.
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| 7. |
- Segergren, Erik, 1974-
(författare)
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Direct Drive Generator for Renewable Power Conversion from Water Currents
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In this thesis permanent magnet direct drive generator for power conversion from water currents is studied. Water currents as a power source involves a number of constrains as well as possibilities, especially when direct drive and permanent magnets are considered. The high power fluxes and low current velocities of a water current, in combination with its natural variations, will affect the way the generator is operated and, flowingly, the appearance of the generator. The work in this thesis can, thus, be categorized into two general topics, generator technology and optimization. Under the first topic, fundamental generator technology is used to increase the efficiency of a water current generator. Under the latter topic, water current generators are optimized to a specific environment. The conclusion drawn from this work is that it is possible to design very low speed direct drive generators with good electromagnetic properties and wide efficiency peak.
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| 8. |
- Sundell, Gustav, 1985, et al.
(författare)
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Redistribution of alloying elements in Zircaloy-2 after in-reactor exposure
- 2014
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 454:1-3, s. 178-185
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Tidskriftsartikel (refereegranskat)abstract
- An atom probe tomography study of the microstructure of a Zircaloy-2 material subjected to 9 annual cycles of BWR exposure has been conducted. Upon dissolution of secondary phase particles, Fe and Cr are seen to reprecipitate in large numbers of clusters and particles of 1-5 nm sizes throughout the Zr metal matrix. Fe and Sn were observed to segregate to ring-shaped features in the metal that are interpreted to be -component vacancy loops. This implies that these two elements play a major role in the irradiation growth phenomenon in Zr alloys, which is believed to be caused by the formation of -loops. Similarly to autoclave-corroded Zr alloys, the formation of a sub-oxide layer of approximate composition ZrO was observed. On the other hand, no oxygen saturated metal phase was detected underneath the oxide scale.
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| 9. |
- Tejland, Pia, 1978, et al.
(författare)
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Detailed analysis of the microstructure of the metal/oxide interface region in Zircaloy-2 after autoclave corrosion testing
- 2011
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Ingår i: ASTM Special Technical Publication. 16th International Symposium on Zirconium in the Nuclear Industry, Chengdu, Sinchuan Province, 9-13 May 2010. - 0066-0558. - 9780803175150 ; 1529 STP, s. 595-617
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Konferensbidrag (refereegranskat)abstract
- Two varieties of Zircaloy-2, with different second phase particle (SPP) size distributions and different corrosion resistance, were oxidized in a steam autoclave. Transmission electron microscopy (TEM) of large thin-foil cross-sections of the oxide and the adjacent metal shows an undulating metal/oxide interface in both materials with a periodicity of slightly less than 1 μm and an amplitude of around 100 nm. The SPPs oxidize slower than the surrounding metal, and the absence of volume increase leads to void and crack formation as the SPPs become embedded in the oxide. On SPP oxidation, iron diffuses out of the particles into the surrounding oxide. A sub-oxide with an oxygen content of approximately 50 at. % and a layer thickness of about 200 nm was observed close to the metal/oxide interface. There is a 200 nm oxygen concentration gradient into the metal, from the level close to the sub-oxide of about 30 at. % down to a few atomic percent. All tin in the matrix is incorporated in the sub-oxide, and no segregation to the metal/oxide interface was found.
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| 10. |
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| 11. |
- Tejland, Pia, 1978, et al.
(författare)
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Oxidation Mechanism in Zircaloy- 2—The Effect of SPP Size Distribution
- 2015
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Ingår i: ASTM Special Technical Publication. - 0066-0558. - 9780803175297 ; 1543, s. 373-403
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Konferensbidrag (refereegranskat)abstract
- The metal/oxide interface region in Zircaloy-2 oxidized in autoclave was studied with transmission electron microscopy (TEM) and atom probe tomography. In addition to waviness on the micrometer scale the metal/oxide interface was found to have irregularities on a finer scale, and metal islands were found especially at metal hills (delayed parts of the oxidation front). The thickness of the sub-oxide layer varies considerably along the interface in the same sample, from 100 to virtually 0 nm. The sub-oxide composition may vary on a very fine scale (down to 5nm), and it can sometimes be a mixture of sub-oxides with different oxygen content. The metal matrix in contact with the sub-oxide is saturated with up to 32 at. % oxygen, and the oxygen diffusion profile in the metal is in approximate agreement with literature data for pure Zr. However, the diffusion length appears to be somewhat larger at interface metal hills than under valleys, probably for both geometrical and stress state reasons. Hydride precipitates, hardly visible in conventional TEM, give a good image contrast when employing high angle annular dark field imaging. A model for the oxidation process is presented, where the creep deformation of the metal close to the interface and the formation of lateral cracks in the oxide are of highest importance. The effect of second phase particle (SPP) size is suggested to be twofold: Small and numerous SPPs give a stronger metal and therefore higher stress in the oxide. Small SPPs also nucleate many more lateral cracks in the oxide, which gives a weaker oxide. Together this leads to formation of large cracks associated with transition in the oxidation rate at an earlier time than for a material with larger and fewer SPPs, and thereby a higher oxidation rate.
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| 12. |
- Varkey, Emma, et al.
(författare)
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Physical activity, self-efficacy and quality of life in patients with chronic pain, assessed during and 1 year after physiotherapy rehabilitation - a prospective follow-up study
- 2022
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Ingår i: Disability and Rehabilitation. - : Informa UK Limited. - 0963-8288 .- 1464-5165. ; 44:22, s. 6730-6737
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Tidskriftsartikel (refereegranskat)abstract
- Purpose The aim of this prospective cohort study was to evaluate the level of physical activity, self-efficacy and health-related quality of life in patients with chronic pain, at baseline and one year after physiotherapy rehabilitation at a specialist pain clinic. Materials and methods All patients who underwent rehabilitation at the physiotherapy unit at the Pain Centre at Sahlgrenska University Hospital/ostra in Gothenburg during a nine-month period were asked to participate in the study. The participants were evaluated regarding self-efficacy, health-related quality of life (HRQoL) and physical activity during physiotherapy treatment and one year later. Physical activity was measured both subjectively (self-reported physical activity) and objectively (accelerometer). Results Out of 42 patients who participated in the baseline evaluation, 28 (19 women and nine men) were included in the one-year follow-up. The patients had increased levels of vigorous physical activity at one-year follow-up, without deterioration of pain. There were no significant changes regarding self-efficacy and HRQoL. Levels of physical activity and perceived physical function may be associated to levels of physical activity 1 year after rehabilitation. Conclusion Patients with chronic pain can increase their level of vigorous physical activity after a period of rehabilitation without deterioration of pain.IMPLICATIONS FOR REHABILIATION Physical activity is an important part of rehabilitation for chronic pain patients, but many patients expect more pain after exercise, which they fear may affect performance and maintenance of physical activity. Patients with chronic pain at a specialist clinic increased their level of vigorous physical activity one year after physiotherapist led rehabilitation without deterioration of pain. Levels of physical activity and perceived physical function during rehabilitation may predict levels of physical activity 1 year after rehabilitation. Physiotherapist led rehabilitation seems to be beneficial for long-term improved physical activity in patients with chronic pain
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| 13. |
- Vikhareva, Olga, et al.
(författare)
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Strategies to increase the rate of vaginal deliveries after cesarean without negative impact on outcomes
- 2022
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Ingår i: Midwifery. - : Elsevier BV. - 0266-6138. ; 106
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Tidskriftsartikel (refereegranskat)abstract
- Objective: To compare the rate of vaginal birth after cesarean section (VBAC), including the maternal and perinatal outcomes, in two historical cohorts before and after the implementation of specific changes in the clinical practice. Design: A retrospective cohort study. Setting: Skåne University Hospital in Malmö, Sweden. Participants: including all women with one previous cesarean section (CS), who delivered during two 4-year periods: 2005–2008 (Group I) and 2013–2016 (Group II). Methods: Medical records were retrieved from the hospital's computerized medical system. The surgical reports of all women delivered by repeat CS were reviewed and the appearance of the lower uterine segment at CS was assessed. The primary outcome was VBAC. Secondary maternal outcomes were uterine rupture/dehiscence, hysterectomy and blood loss. The secondary perinatal outcomes were cord blood pH < 7.05 and perinatal mortality rate. Differences for categorical data were studied using the chi-square test and Fisher's exact test. To assess differences for continuous data t-tests were used. To determine which factors predicted VBAC both univariate and multivariate logistic regression analysis with the likelihood ratio test were performed. A two-tailed P-value < 0.05 was considered statistically significant Findings: 2017 patients were included to the study: 792 patients in Group I and 1225 in Group II. The rate of trial of labor after cesarean (TOLAC) was 65.0% and 76.9% and the VBAC rate was 49.8% and 62.0% in Group I and II respectively (p < 0.0001). Maternal and perinatal adverse outcomes were not statistically different between the two groups. Key conclusions and implications for practice: Appropriate management of women with one previous CS might increase the VBAC rate without a negative impact on maternal or perinatal outcomes. The antenatal teamwork has the greatest contribution to VBAC rate by increasing the number of women undergoing TOLAC.
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