| 1. |
- Höglund, Linda, 1974-, et al.
(författare)
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Energy level scheme of InAs/InxGa1-xAs/GaAs quantum-dots-in-a-well infrared photodetector structures
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - Woodbury, NY : American Physical Society. - 1098-0121 .- 1550-235X. ; 82:3, s. 035314-
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Tidskriftsartikel (refereegranskat)abstract
- A thorough investigation of quantum-dots-in-a-well structures for infrared photodetector applications has been performed employing different experimental techniques. The electronic structure of self-assembled InAs quantum dots embedded in an In0.15Ga0.85As/GaAs quantum well (QW) was deduced from photoluminescence (PL) and PL excitation (PLE) spectroscopy. From polarization-dependent PL it was revealed that the quantum dots hold two electron energy levels and two heavy-hole levels. Tunnel capacitance spectroscopy confirmed an electron energy level separation of about 50 meV, and additionally, that the conduction-band ground state and excited state of the dots are twofold and fourfold degenerates, respectively. Intersubband photocurrent spectroscopy, combined with simultaneous interband pumping of the dots, revealed a dominant transition at 150 meV (8.5 mu m) between the ground state of the quantum dots and the excited state of the QW. Results from detailed full three-dimensional calculations of the electronic structure, including effects of composition intermixing and interdot interactions, confirm the experimentally unravelled energy level scheme of the dots and well.
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| 2. |
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| 3. |
- Pettersson, Håkan, et al.
(författare)
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Quantum Dots-in-a-Well Infrared Photodetectors-Electronic Structure and Optical Properties
- 2010
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Ingår i: Bulletin of American Physical Society. - : American Physical Society.
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Konferensbidrag (refereegranskat)abstract
- Quantum dots-in-a-well (DWELL) infrared photodetectors is a new class of nanophotonic devices with the potential of significantly increasing the performance and reducing the cost of infrared detectors. Here we present a comprehensive study of DWELL photodetector structures using a variety of optical techniques (PL, PLE, and PC). Complementary tunnel capacitance measurements support the electronic structure obtained from the optical measurements. A detailed energy level scheme based on the experimental findings is presented and compared to theoretical modeling. The presented work show the importance of combining different electrical and optical techniques to obtain a consistent model of complicated quantum structures which is crucial for the development of future nanophotonic devices.
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| 4. |
- Uhlén, Mathias, et al.
(författare)
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A human protein atlas for normal and cancer tissues based on antibody proteomics
- 2005
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Ingår i: Molecular & Cellular Proteomics. - 1535-9476 .- 1535-9484. ; 4:12, s. 1920-1932
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Tidskriftsartikel (refereegranskat)abstract
- Antibody-based proteomics provides a powerful approach for the functional study of the human proteome involving the systematic generation of protein-specific affinity reagents. We used this strategy to construct a comprehensive, antibody-based protein atlas for expression and localization profiles in 48 normal human tissues and 20 different cancers. Here we report a new publicly available database containing, in the first version, similar to 400,000 high resolution images corresponding to more than 700 antibodies toward human proteins. Each image has been annotated by a certified pathologist to provide a knowledge base for functional studies and to allow queries about protein profiles in normal and disease tissues. Our results suggest it should be possible to extend this analysis to the majority of all human proteins thus providing a valuable tool for medical and biological research.
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| 5. |
- Abbasiverki, Roghayeh, et al.
(författare)
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Nonlinear Behaviour of Concrete Buttress Dams under High-Frequency Excitations Taking into Account Topographical Amplifications
- 2021
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Ingår i: Shock and Vibration. - : Hindawi Limited. - 1070-9622 .- 1875-9203. ; 2021, s. 1-22
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Tidskriftsartikel (refereegranskat)abstract
- Concrete buttress dams could potentially be susceptible to high-frequency vibrations, especially in the cross-stream direction, due to their slender design. Previous studies have mainly focused on low-frequency vibrations in stream direction using a simplified foundation model with the massless method, which does not consider topographic amplifications. This paper therefore investigates the nonlinear behaviour of concrete buttress dams subjected to high-frequency excitations, considering cross-stream vibrations. For comparison, the effect of low-frequency excitations is also investigated. The influence of the irregular topography of the foundation surface on the amplification of seismic waves at the foundation surface and thus in the dam is considered by a rigorous method based on the domain-reduction method using the direct finite element method. The sensitivity of the calculated response of the dam to the free-field modelling approach is investigated by comparing the result with analyses using an analytical method based on one-dimensional wave propagation theory and a massless approach. Available deconvolution software is based on the one-dimensional shear wave propagation to transform the earthquake motion from the foundation surface to the corresponding input motion at depth. Here, a new deconvolution method for both shear and pressure wave propagation is developed based on an iterative time-domain procedure using a one-dimensional finite element column. The examples presented showed that topographic amplifications of high-frequency excitations have a significant impact on the response of this type of dam. Cross-stream vibrations reduced the safety of the dam due to the opening of the joints and the increasing stresses. The foundation modelling approach had a significant impact on the calculated response of the dam. The massless method produced unreliable results, especially for high-frequency excitations. The free-field modelling with the analytical method led to unreliable joint openings. It is therefore recommended to use an accurate approach for foundation modelling, especially in cases where nonlinearity is considered.
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| 6. |
- Abbasiverki, Roghayeh
(författare)
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Numerical modelling considerations for analysis of concrete hydraulic structures subjected to high-frequency seismic loads
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Concrete hydraulic structures are of great importance in today's society. When situated in areas with hard bedrock, these structures may become extra vulnerable to seismic excitations as these here are dominated by high-frequency vibrations which can have disastrous consequences for slender structures. The aim of this thesis was to investigate special considerations that must be made when conducting analyses of such hydraulic structures during high-frequency excitations. Underground and on the ground structures were investigated separately. Underground concrete pipelines and concrete buttress dams were selected for the study because their behaviour when exposed to seismic excitations is dominated by their stiffness. The most effective models and modelling methods for the seismic analyses of such structures were implemented and evaluated. Two-dimensional finite element (FE) models were developed for the dynamic analysis of underground concrete pipelines loaded by seismic waves propagating from bedrock through soil. The interaction between the bedrock and the surrounding soil was investigated with respect to rock geometry and soil properties. The surface of dam foundations is commonly irregular, resulting in nonuniform motions at the dam-foundation interface. The free-field modelling methods for concrete dam foundations were adapted in order to accurately describe the propagation of earthquake vibrations from the source to the ground surface. The implementation of a threedimensional FE model for concrete buttress dams was investigated. Two different methods for free-field modelling are presented, which can be implemented independently of the software used. The seismic loads are applied as effective earthquake forces at non-reflecting boundaries. In the first method, the free-field motions at the non-reflecting boundaries are determined by the so-called domain reduction method using the direct FE calculation. In the second method, the free-field motions are analytically determined based on the onedimensional wave propagation theory. The results are also compared with the massless foundation modelling approach, in which the topographical amplifications are neglected. It was demonstrated that a two-dimensional model can effectively account for pipeline behaviour. The most important aspect of the models is the ability to capture bending deformations, as segmented structures such as pipelines are vulnerable in this respect. Nonuniform bedrock reduces the safety of concrete pipeline, especially because of bending deformations in the pipe and joints. The massless method gave unreliable results for analyses of dams, especially for high-frequency excitations. The analytical method was also unreliable in estimating the non-linear behaviour of the dams. But, a new time domain deconvolution method was developed to transform the earthquake motion from the foundation surface to the corresponding input motion at depth. It wasfound that free-field modelling of foundations using the direct FE method can accurately capture the topographic amplifications of the seismic excitations. It was shown that a three-dimensional model is required for seismic evaluation of concrete buttress dams. The topographic amplification of high-frequency waves at the surface of canyons had a significant effect on the response of this type of dam.
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| 7. |
- Abedin, Ahmad, et al.
(författare)
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Germanium on Insulator Fabrication for Monolithic 3-D Integration
- 2018
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Ingår i: IEEE Journal of the Electron Devices Society. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 2168-6734. ; 6:1, s. 588-593
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Tidskriftsartikel (refereegranskat)abstract
- A low temperature (T-max = 350 degrees C) process for Germanium (Ge) on insulator (GOI) substrate fabrication with thicknesses of less than 25 nm is reported in this paper. The process is based on a single step epitaxial growth of a Ge/SiGe/Ge stack on Si, room temperature wafer bonding and an etch-back process using Si0.5Ge0.5 as an etch-stop layer. GOI substrates with surface roughness below 0.5 nm, 0.15% tensile strain, thickness nonuniformity of less than 3 nm and residual p-type doping of less than 1016 cm(-3) were fabricated. Ge pFETs are fabricated (T-max = 600 degrees C) on the GOI wafer with 70% yield. The devices exhibit a negative threshold voltage of -0.18 V and 60% higher mobility than the SOI pFET reference devices.
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| 8. |
- Abedin, Ahmad, et al.
(författare)
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GOI fabrication for monolithic 3D integration
- 2018
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Ingår i: 2017 IEEE SOI-3D-Subthreshold Microelectronics Unified Conference, S3S 2017. - : Institute of Electrical and Electronics Engineers (IEEE). - 9781538637654 ; , s. 1-3
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Konferensbidrag (refereegranskat)abstract
- A low temperature (Tmax=350 °C) process for Ge on insulator (GOI) substrate fabrication with thicknesses of less than 25 nm is reported in this work. The process is based on a single step epitaxial growth of a Ge/SiGe/Ge stack on Si, room temperature wafer bonding, and an etch-back process using Si0.5Ge0.5 as an etch-stop layer. Using this technique, GOI substrates with surface roughness below 0.5 nm, thickness nonuniformity of less than 3 nm, and residual p-type doping of less than 1016 cm-3 are achieved. Ge pFETs are fabricated (Tmax=600 °C) on the GOI wafer with 70% yield. The devices exhibit a negative threshold voltage of-0.18 V and 60% higher mobility than the SOI pFET reference devices.
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| 9. |
- Bech-Hanssen, Odd, 1956, et al.
(författare)
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Pressure reflection in the pulmonary circulation in patients with severe mitral regurgitation indicates adverse postoperative outcome.
- 2013
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Ingår i: European Journal Cardio-Thoracic Surgery. - : Oxford University Press (OUP). - 1010-7940 .- 1873-734X. ; 44:6, s. 1037-1044
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVES: Severe pulmonary hypertension (PH) is a known risk factor in valvular surgery. In the present study, we hypothesized that the assessment of pressure reflection (PR) in the pulmonary circulation, indicating increased pulmonary vascular resistance, might improve the identification of patients with increased morbidity and mortality following surgery for severe mitral regurgitation. METHODS: A total of 103 patients without atrial fibrillation were divided into three groups: Group 1 (n = 48), patients without PR; Group 2 (n = 36), patients with PR and pulmonary artery systolic pressure (PASP) ≤60 mmHg and Group 3 (n = 19), patients with PR and PASP >60 mmHg. Three variables related to PR were selected: the acceleration time in the right ventricular outflow tract (RVOT), the interval between peak velocity in the RVOT and peak tricuspid regurgitant jet velocity and the right ventricular pressure increase after peak RVOT velocity. RESULTS: There were no differences between groups in age, ejection fraction, need for coronary bypass grafting or creatinine. Patients with PR (Groups 2 and 3) had more use of vasoactive drugs (overall P < 0.0001, Group 1 vs Group 2 P = 0.018). The proportion of patients with >24 h in the intensive care unit was 27% in Group 1, 54% in Group 2 and 84% in Group 3 (overall P < 0.0001, Group 1 vs Group 2 P = 0.006). The in-hospital mortality in patients without PR (n = 49) was 0% compared with 10.9% in patients with PR (P = 0.029). CONCLUSIONS: Echocardiography assessment of PR in the pulmonary circulation and severe PH may identify patients with adverse outcome following mitral surgery.
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| 10. |
- Bergman, Eva, et al.
(författare)
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Does one's sense of coherence change after an acute myocardial infarction?: A two-year longitudinal study in Sweden.
- 2011
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Ingår i: Nursing and Health Sciences. - : Blackwell Publishing Asia Pty Ltd. - 1441-0745 .- 1442-2018. ; 13:2, s. 156-163
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to assess changes in the sense of coherence of patients who had suffered their first myocardial infarction. Out of 100 patients at the start of the study, these changes were evaluated in 66 men and 18 women aged 36–70 years. Generally, the sense of coherence was found to be stable among the whole group, but there were significant individual variations in its development in some of the participants over the following years. Even the individuals with an initally high sense of coherence could experience a decrease in its level. The changes that were found in the men can be explained by their marital status, level of treatment satisfaction, disease perception/quality of life, physical limitation, and alcohol intake and/or tobacco use at the baseline. An unexpected finding was that the single men with an initially high sense of coherence experienced a decreased level over time. In order to maintain or increase patients' sense of coherence, it is important for nurses to help them identify their risk factors and to provide conditions for individualized cardiac rehabilitation in order to avoid another myocardial infarction.
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| 11. |
- Bergman, Eva, et al.
(författare)
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Longitudinal study of patients after myocardial infarction : Sense of coherence, quality of life, and symptoms
- 2009
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Ingår i: Heart & Lung. - : Elsevier BV. - 0147-9563 .- 1527-3288. ; 38:2, s. 129-140
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Myocardial infarction has pronounced effects on an individual that demand changes in lifestyle. Health is influenced by whether the individual experiences the world as comprehensible, meaningful, and manageable, that is, has a sense of coherence (SOC). High SOC scores indicate that the individual probably manages the situation by understanding the context and connections: action and effect. OBJECTIVE: The study objective was to identify the SOC, assess the quality of life (Short Form-12 Health Survey Questionnaire), assess the symptoms using the Seattle Angina Questionnaire, and create health curves from a baseline for patients with a first myocardial infarction. METHODS: A longitudinal and predictive Study of 100 participants in the heart care unit of a county hospital in southern Sweden was performed. RESULTS: Women score lower on SOC than men. Persons with high SOC scores have fewer angina attacks, are more physically active, drink more alcohol, are more satisfied with their treatments, and have better disease perception. CONCLUSION: By following SOC scores, a trend emerges that Suggests it may be a useful tool for identifying those who will need extra support.
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| 12. |
- Bergman, Eva, et al.
(författare)
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Meaningfulness is not the most important component for changes in sense of coherence
- 2012
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Ingår i: European Journal of Cardiovascular Nursing. - : Oxford University Press (OUP). - 1474-5151 .- 1873-1953. ; 11:3, s. 331-338
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Tidskriftsartikel (refereegranskat)abstract
- Background Sense of coherence is a theoretical construct which is used to measure the degree to which a person finds the world comprehensible, manageable and meaningful.Aim The main aim of the present study was to assess the hypothesis of Antonovsky that meaningfulness is the most crucial component in sense of coherence. The second aim was to explore the importance of its components and factors at baseline on sense of coherence changes and if the findings can be used in cardiac rehabilitation.Methods One hundred patients, who suffered a primary myocardial infarction were followed during two years. The instruments used were; sense of coherence questionnaire-13, 12-item short-form health survey questionnaire, the Seattle Angina Questionnaire and Health Curve.Results Thirty-nine percent of the participants fulfilled Antonovsky's hypothesis. Comprehensibility and the baseline factors of smoking, alcohol use, marital status and disease perception proved to be of importance for sense of coherence changes over time.Conclusion The hypothesis that meaningfulness is the most crucial component in sense of coherence is rejected for patients with primary myocardial infarction. Comprehensibility is more important than meaningfulness for changes in sense of coherence. Nurses therefore have an important task to increase comprehensibility and sense of coherence by providing information and knowledge about myocardial infarction and lifestyle changes at an early stage. The information should be given in an individualized and easily understandable way from a salutogenic perspective, which means to identify and work with factors that can contribute to preserving and promoting health.
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| 13. |
- Bergman, Eva, et al.
(författare)
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The impact of comprehensibility and sense of coherence in the recovery of patients with myocardial infarction : a long-term follow-up study
- 2012
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Ingår i: European Journal of Cardiovascular Nursing. - : Oxford University Press (OUP). - 1474-5151 .- 1873-1953. ; 11:3, s. 276-283
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Tidskriftsartikel (refereegranskat)abstract
- Background: After being through a myocardial infarction (MI), a severe recovery period ensues for the patient. Longterm follow-ups are helpful, but what this should include differs between patients. Today there is no established approach to identify needs for support after an MI. Aim: The aim was to describe sense of coherence (SOC) over time in relation to sex, as well as further SOC in relation to quality of life (QoL) and treatment satisfaction in patients with an MI. Methods. This study had an observational and longitudinal design and followed 18 women and 60 men with an acute MI for 49-67 months after the onset of MI. Instruments used were the SOC-13 and the Seattle Angina Questionnaire. Results: Women scored lower SOC than men. A main effect of time was shown for comprehensibility which increased significantly from baseline to the long-term follow-up. Women increased from a lower level to an equal level as men at the long-term follow-up. The total SOC was significantly associated with QoL and treatment satisfaction. Conclusion: High comprehensibility and high SOC give the patient a better basis to handle life after MI. Thus, healthcare professionals should keep in mind that SOC and especially comprehensibility have meaning for the patient's ability to handle her or his recovery. Healthcare professionals need to together with the patient identify and work with lifestyle factors that contribute to increased comprehensibility about the disease, which gives the patient the foundation to preserve and promote her or his health both in the short and long term.
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| 14. |
- Betancourt, Lazaro Hiram, et al.
(författare)
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The human melanoma proteome atlas-Defining the molecular pathology
- 2021
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Ingår i: Clinical and Translational Medicine. - : Wiley. - 2001-1326. ; 11:7, s. 1-20
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Tidskriftsartikel (refereegranskat)abstract
- The MM500 study is an initiative to map the protein levels in malignant melanoma tumor samples, focused on in-depth histopathology coupled to proteome characterization. The protein levels and localization were determined for a broad spectrum of diverse, surgically isolated melanoma tumors originating from multiple body locations. More than 15,500 proteoforms were identified by mass spectrometry, from which chromosomal and subcellular localization was annotated within both primary and metastatic melanoma. The data generated by global proteomic experiments covered 72% of the proteins identified in the recently reported high stringency blueprint of the human proteome. This study contributes to the NIH Cancer Moonshot initiative combining detailed histopathological presentation with the molecular characterization for 505 melanoma tumor samples, localized in 26 organs from 232 patients.
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| 15. |
- Björklund, Erik, et al.
(författare)
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Comparison of Midterm Outcomes Associated With Aspirin and Ticagrelor vs Aspirin Monotherapy After Coronary Artery Bypass Grafting for Acute Coronary Syndrome.
- 2021
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Ingår i: JAMA network open. - : American Medical Association (AMA). - 2574-3805. ; 4:8
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Tidskriftsartikel (refereegranskat)abstract
- Guidelines recommend dual antiplatelet therapy after coronary artery bypass grafting (CABG) for patients with acute coronary syndrome (ACS). However, the evidence for these recommendations is weak.To compare midterm outcomes after CABG in patients with ACS treated postoperatively with acetylsalicylic acid (ASA) and ticagrelor or with ASA monotherapy.This cohort study used merged data from several national registries of Swedish patients who were diagnosed with ACS and subsequently underwent CABG. All included patients underwent isolated CABG in Sweden between 2012 and 2017 with an ACS diagnosis less than 6 weeks before the procedure, survived 14 days after discharge from hospital, and were treated postoperatively with ASA plus ticagrelor or ASA monotherapy. A multivariable Cox regression model was used for the main analysis, and propensity score-matched models were performed as sensitivity analysis. Data were analyzed between May and September 2020.Postoperative antiplatelet treatment, defined as filled prescriptions, with either ASA and ticagrelor or ASA only.Major adverse cardiovascular events (MACE), defined as all-cause mortality, myocardial infarction, and stroke, and major bleeding, at 12 months and at the end of follow-up.A total of 6558 patients (5281 [80.5%] men; mean [SD] age at surgery, 67.6 [9.3] years) were included; 1813 (27.6%) were treated with ASA plus ticagrelor and 4745 (72.4%) were treated with ASA monotherapy. Crude MACE rate was 3.0 per 100 person years (95% CI, 2.5-3.6 per 100 person years) in the ASA plus ticagrelor group and 3.8 per 100 person years (95% CI, 3.5-4.1 per 100 person years) in the ASA group. After adjustment, there was no significant difference in MACE risk between ASA plus ticagrelor vs ASA only, neither during the first 12 months (adjusted hazard ratio [aHR], 0.84; 95% CI, 0.58-1.21; P=.34) or during total follow-up (aHR, 0.89; 95% CI, 0.71-1.11; P=.29). The use of ASA plus ticagrelor was associated with a significantly increased risk for major bleeding during the first 12 months (aHR, 1.90; 95% CI, 1.16-3.13; P=.011). Sensitivity analyses confirmed the results.In patients with ACS who survived 2 weeks after CABG, no significant difference in the risk of death or ischemic events could be demonstrated between ASA plus ticagrelor and patients treated with ASA only, while the risk for major bleeding was higher in patients treated with ASA plus ticagrelor. Sufficiently powered prospective randomized trials comparing different antiplatelet therapy strategies after CABG are warranted.
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| 16. |
- Björklund, Erik, et al.
(författare)
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Postdischarge major bleeding, myocardial infarction, and mortality risk after coronary artery bypass grafting
- 2023
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Ingår i: HEART. - 1355-6037 .- 1468-201X.
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Tidskriftsartikel (refereegranskat)abstract
- Objective To investigate the incidence and mortality risk associated with postdischarge major bleeding after coronary artery bypass grafting (CABG), and relate this to the incidence of, and mortality risk from, postdischarge myocardial infarction.Methods All patients undergoing first-time isolated CABG in Sweden in 2006-2017 and surviving 14 days after hospital discharge were included in a cohort study. Individual patient data from the SWEDEHEART Registry and five other mandatory nationwide registries were merged. Piecewise Cox proportional hazards models were used to investigate associations between major bleeding, defined as hospitalisation for bleeding, with subsequent mortality risk. Similar Cox proportional hazards models were used to investigate the association between postdischarge myocardial infarction and mortality risk.Results Among 36 633 patients, 2429 (6.6%) had a major bleeding event and 2231 (6.1%) had a myocardial infarction. Median follow-up was 6.0 (range 0-11) years. Major bleeding was associated with higher mortality risk <30 days (adjusted HR (aHR)=20.2 (95% CI 17.3 to 23.5)), 30-365 days (aHR=3.8 (95% CI 3.4 to 4.3)) and >365 days (aHR=1.8 (95% CI 1.7 to 2.0)) after the event. Myocardial infarction was associated with higher mortality risk <30 days (aHR=20.0 (95% CI 16.7 to 23.8)), 30-365 days (aHR=4.1 (95% CI 3.6 to 4.8)) and >365 days (aHR=1.8 (95% CI 1.7 to 2.0)) after the event.Conclusions The increase in mortality risk associated with a postdischarge major bleeding after CABG is substantial and is similar to the mortality risk associated with a postdischarge myocardial infarction.
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| 17. |
- Björklund, Erik, et al.
(författare)
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Postoperative platelet function is associated with severe bleeding in ticagrelor-treated patients
- 2019
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Ingår i: Interactive Cardiovascular and Thoracic Surgery. - : Oxford University Press (OUP). - 1569-9293 .- 1569-9285. ; 28:5, s. 709-715
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: Preoperative testing of platelet function predicts bleeding risk in cardiac surgery patients treated with dual antiplatelet therapy, but the value of postoperative platelet function testing, reflecting both preoperative antiplatelet therapy and perioperative changes in platelet function, has not been evaluated. Methods: Seventy-four patients with acute coronary syndrome treated with acetylsalicylic acid and ticagrelor within 5 days before cardiac surgery were included in a prospective observational study. Platelet aggregation induced by adenosine diphosphate, arachidonic acid and thrombin receptor-activating peptide was assessed with multiple electrode impedance aggregometry immediately before surgery and 2 h after weaning off cardiopulmonary bypass. Receiver operating characteristic curves were used to determine any association between platelet aggregation and severe bleeding according to the universal definition of perioperative bleeding in adult cardiac surgery. Results: Severe bleeding occurred in 25 of 74 patients (34%). Preoperative and postoperative adenosine diphosphate-induced platelet aggregations were associated with bleeding, with comparable areas under the receiver operating characteristic curve [0.77 (95% confidence interval 0.65-0.89) vs 0.75 (0.62-0.87)]. Postoperative arachidonic acid-and thrombin receptor-activating peptide-induced aggregation had markedly smaller areas under the curve. There were significant correlations between preoperative and postoperative platelet aggregation induced by adenosine diphosphate (r2 = 0.77, P < 0.001), arachidonic acid (r2 = 0.24, P < 0.001) and thrombin receptoractivating peptide (r2 = 0.21, P < 0.001) but with large interindividual variations. Conclusions: Poor postoperative platelet function was associated with severe bleeding, with accuracy comparable to that of preoperative platelet function. There was a correlation between preoperative and postoperative platelet function, but the predictability in an individual patient was limited. © 2018 The Author(s). Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.
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| 18. |
- Björklund, Erik, et al.
(författare)
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Secondary prevention medications after coronary artery bypass grafting and long-term survival : a population-based longitudinal study from the SWEDEHEART registry.
- 2019
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Ingår i: European Heart Journal. - : Oxford University Press. - 0195-668X .- 1522-9645. ; 41:17, s. 1653-1661
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Tidskriftsartikel (refereegranskat)abstract
- AIMS: To evaluate the long-term use of secondary prevention medications [statins, β-blockers, renin-angiotensin-aldosterone system (RAAS) inhibitors, and platelet inhibitors] after coronary artery bypass grafting (CABG) and the association between medication use and mortality.METHODS AND RESULTS: All patients who underwent isolated CABG in Sweden from 2006 to 2015 and survived at least 6 months after discharge were included (n = 28 812). Individual patient data from SWEDEHEART and other mandatory nationwide registries were merged. Multivariable Cox regression models using time-updated data on dispensed prescriptions were used to assess associations between medication use and long-term mortality. Statins were dispensed to 93.9% of the patients 6 months after discharge and to 77.3% 8 years later. Corresponding figures for β-blockers were 91.0% and 76.4%, for RAAS inhibitors 72.9% and 65.9%, and for platelet inhibitors 93.0% and 79.8%. All medications were dispensed less often to patients ≥75 years. Treatment with statins [hazard ratio (HR) 0.56, 95% confidence interval (95% CI) 0.52-0.60], RAAS inhibitors (HR 0.78, 95% CI 0.73-0.84), and platelet inhibitors (HR 0.74, 95% CI 0.69-0.81) were individually associated with lower mortality risk after adjustment for age, gender, comorbidities, and use of other secondary preventive drugs (all P < 0.001). There was no association between β-blockers and mortality risk (HR 0.97, 95% CI 0.90-1.06; P = 0.54).CONCLUSION: The use of secondary prevention medications after CABG was high early after surgery but decreased significantly over time. The results of this observational study, with inherent risk of selection bias, suggest that treatment with statins, RAAS inhibitors, and platelet inhibitors is essential after CABG whereas the routine use of β-blockers may be questioned.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
- Burman, Erik, et al.
(författare)
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Concussed athletes are more prone to injury both before and after their index concussion : A data base analysis of 699 concussed contact sports athletes
- 2016
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Ingår i: BMJ Open Sport and Exercise Medicine. - : BMJ Publishing Group Ltd. - 2055-7647. ; 2:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ice hockey and football players suffering concussions might have an increased risk for injuries afterwards. We aimed to investigate if concussions predisposed athletes for subsequent sport injuries.Methods: Patient data were obtained from a data base established at the University Hospital in Umea, Sweden. Athletes who had suffered a concussion were included if they had been aged between 15 and 35 years of age, and played ice hockey, football (soccer), floorball and handball. They were studied in terms of all new or previous injuries during 24 months before and after their concussion. Results were compared with a control group of athletes from the same four sports with an ankle injury.Results: Athletes with a concussion were more likely to sustain injuries compared with the control group, both before (OR 1.98. 95% CI 1.45 to 2.72) and after the concussion (OR 1.72. 95% CI 1.26 to 2.37). No increase in frequency of injury was found after a concussion compared with before. This was true for athletes in all four sports and for both sexes.Conclusions: This study indicates that athletes sustaining a concussion may have a more aggressive or risk-taking style of play than their counterparts. Our data do not suggest that a concussion injury, per se, leads to subsequent injuries.
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| 23. |
- Capriata, Corrado Carlo Maria
(författare)
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Dynamics and Intrinsic Variability of Spintronic Devices
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Spintronics is a scientific domain focusing on utilizing electron spin for information processing. This is the element that distinguishes it from electronics, which only utilizes the charge of electrons. A common purpose of spintronic devices is to implement additional functionalities to state-of-the-art Complementary Metal-Oxide Semiconductor (CMOS) technology. The aim of this work was to assess the intrinsic variabilities of Nano-Constriction Spin Hall Nano-Oscillators (NC-SHNOs) and the dynamics of Perpendicular Magnetic Tunnel Junctions (pMTJs). The first part of the thesis focuses on NC-SHNO and two-dimensional arrays. They are nanometer-sized microwave oscillators, allowing for a wide frequency tuning range, and are compatible with CMOS Back End Of Line (BEOL). These devices are based on a heavy metal/ferromagnetic bilayer. Environmental conditions during processing, fabrication techniques, and temperature of operation can all create variabilities in the device's functioning. Crystallization grains naturally form during the sputtering of the metals. Atomic Force Microscope (AFM) characterization showed the grains being of different shapes, about 30 nm in size. Here, the aim was to develop a simulation technique based on importing the measured grain structure into micromagnetic simulations. Their results match the device-to-device variability and multi-modal behavior found in microwave measurements. Moreover, the presence of grains influences the synchronization of the arrays.The second part of this work focuses on pMTJ. These non-volatile memory elements have two metastable states, parallel (P) and antiparallel (AP), separated by an energy barrier Eb. Here, the aim was to show their potential as True Random Number Generators (TRNGs). A pulse-activated measurement set-up was used to realize random bitstreams. The randomness was confirmed by the National Institute of Standards and Technology Statistical Testing Suite (NIST-STS). After one whitening Exclusive OR (XOR) stage, all tests were successfully passed.The assessment was completed with the development of a model describing both macrospin and domain wall-mediated magnetization reversals, i.e. switching between P and AP. The analysis of the reversal dynamics was carried out with micromagnetic simulations and String Method calculations. As expected, Eb is lowered by the field and by decreasing the device size. This allows for faster fluctuations, marking the device as a potential TRNG. Both the switching attempt frequency and the energy barrier were explored by finite-temperature micromagnetic simulations.This thesis shows the potential of realistic simulations combined with measurements to assess oscillators. It also shows the efficacy of spintronic devices as 10s-MHz TRNG.
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| 24. |
- Dacasa, Hugo, et al.
(författare)
-
Single-shot extreme-ultraviolet wavefront measurements of high-order harmonics
- 2019
-
Ingår i: Optics Express. - 1094-4087. ; 27:3, s. 2656-2670
-
Tidskriftsartikel (refereegranskat)abstract
- We perform wavefront measurements of high-order harmonics using an extreme-ultraviolet (XUV) Hartmann sensor and study how their spatial properties vary with different generation parameters, such as pressure in the nonlinear medium, fundamental pulse energy and duration as well as beam size. In some conditions, excellent wavefront quality (up to 휆/11) was obtained. The high throughput of the intense XUV beamline at the Lund Laser Centre allows us to perform single-shot measurements of both the full harmonic beam generated in argon and individual harmonics selected by multilayer mirrors. We theoretically analyze the relationship between the spatial properties of the fundamental and those of the generated high-order harmonics, thus gaining insight into the fundamental mechanisms involved in high-order harmonic generation (HHG).
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| 25. |
- Donetti, L., et al.
(författare)
-
Hole effective mass in silicon inversion layers with different substrate orientations and channel directions
- 2011
-
Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 110:6, s. 063711-
-
Tidskriftsartikel (refereegranskat)abstract
- We explore the possibility to define an effective mass parameter to describe hole transport in inversion layers in bulk MOSFETs and silicon-on-insulator devices. To do so, we employ an accurate and computationally efficient self-consistent simulator based on the six-band k . p model. The valence band structure is computed for different substrate orientations and silicon layer thicknesses and is then characterized through the calculation of different effective masses taking account of the channel direction. The effective masses for quantization and density of states are extracted from the computed energy levels and subband populations, respectively. For the transport mass, a weighted averaging procedure is introduced and justified by comparing the results with hole mobility from experiments and simulations.
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| 26. |
- Donetti, L., et al.
(författare)
-
On the effective mass of holes in inversion layers
- 2011
-
Ingår i: International Conference on Ultimate Integration on Silicon. - 9781457700903 ; , s. 50-53
-
Konferensbidrag (refereegranskat)abstract
- We study hole inversion layers in bulk MOSFETs and silicon-on-insulator devices employing a self-consistent simulator based on the six-band kp model. Valence Band structure is computed for different device orientations and silicon layer thicknesses, and then it is characterized through the calculation of different effective masses.
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| 27. |
- Driussi, F., et al.
(författare)
-
On the electron mobility enhancement in biaxially strained Si MOSFETs
- 2008
-
Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 52:4, s. 498-505
-
Tidskriftsartikel (refereegranskat)abstract
- This paper reports a detailed experimental and simulation study of the electron mobility enhancement induced by the biaxial strain in (001) silicon MOSFETs. To this purpose, ad hoc test structures have been fabricated on strained Si films grown on different SiGe virtual substrates and the effective mobility of the electrons has been extracted. To interpret the experimental results, we performed simulations using numerical solutions of Schroedinger-Poisson equations to calculate the charge and the momentum relaxation time approximation to calculate the mobility. The mobility enhancement with respect to the unstrained Si device has been analyzed as a function of the Ge content of SiGe substrates and of the operation temperature.
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| 28. |
- Eklund, Anders, 1986-
(författare)
-
Microwave Frequency Stability and Spin Wave Mode Structure in Nano-Contact Spin Torque Oscillators
- 2016
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The nano-contact spin torque oscillator (NC-STO) is an emerging device for highly tunable microwave frequency generation in the range from 0.1 GHz to above 65 GHz with an on-chip footprint on the scale of a few μm. The frequency is inherent to the magnetic material of the NC-STO and is excited by an electrical DC current by means of the spin torque transfer effect. Although the general operation is well understood, more detailed aspects such as a generally nonlinear frequency versus current relationship, mode-jumping and high device-to-device variability represent open questions. Further application-oriented questions are related to increasing the electrical output power through synchronization of multiple NC-STOs and integration with CMOS integrated circuits.This thesis consists of an experimental part and a simulation part. Experimentally, for the frequency stability it is found that the slow but strong 1/f-type frequency fluctuations are related to the degree of nonlinearity and the presence of perturbing, unexcited modes. It is also found that the NC-STO can exhibit up to three propagating spin wave oscillation modes with different frequencies and can randomly jump between them. These findings were made possible through the development of a specialized microwave time-domain measurement circuit. Another instrumental achievement was made with synchrotron X-rays, where we image dynamically the magnetic internals of an operating NC-STO device and reveal a spin wave mode structure with a complexity significantly higher than the one predicted by the present theory.In the simulations, we are able to reproduce the nonlinear current dependence by including spin wave-reflecting barriers in the nm-thick metallic, magnetic free layer. A physical model for the barriers is introduced in the form of metal grain boundaries with reduced magnetic exchange coupling. Using the experimentally measured average grain size of 30 nm, the spin wave mode structure resulting from the grain model is able to reproduce the experimentally found device nonlinearity and high device-to-device variability.In conclusion, the results point out microscopic material grains in the metallic free layer as the reason behind the nonlinear frequency versus current behavior and multiple propagating spin wave modes and thereby as a source of device-to-device variability and frequency instability.
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| 29. |
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| 30. |
- Enzell, Jonas, et al.
(författare)
-
Modellförsök stärker betongdammars säkerhet
- 2023
-
Ingår i: Bygg och Teknik. - 0281-658X .- 2002-8350. ; 115:6
-
Tidskriftsartikel (populärvet., debatt m.m.)abstract
- Dammhaverier är mycket ovanliga och därför är kunskapen om brottförloppet vid ett potentiellt dammbrott begränsad. Uppstår brottet utan förvarning, eller finns tidiga tecken på allvarliga problem? Hur utvecklas brottsbräschen under brottförloppet? Detta är frågor som blivit än mer aktuella efter tre internationella dammhaverier under 2023. För att söka svar har en serie skalmodellförsök utförts där haverier av betongdammar simuleras. En viktig parameter vid säkerhetsbedömningen av en betongdamm består i att utvärdera dess stabilitet. Förenklat görs dettag enom att jämföra om dammkroppens vikt är tillräcklig för att stå emot lasten från vattnets tryck. Traditionellt beaktas enbart en mindre del av en betongdamm när dess stabilitet utvärderas men de nya försöken indikerar att det vore eftersträvansvärt att undersöka hela dammen samtidigt eftersom lasten fördelas mellan konstruktionsdelarna. Många betongdammars tillstånd övervakas idag genom automatiska mätningarav till exempel vattenstånd, förskjutningar och grundvattentryck. Dock finns det ingen standardiserad metod för att definiera larmgränser,vilket detta projekt syftar till att utveckla i framtiden.
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| 31. |
- Enzell, Jonas, et al.
(författare)
-
Physical Model Tests of Concrete Buttress Dams with Failure Imposed by Hydrostatic Water Pressure
- 2023
-
Ingår i: Water. - : MDPI. - 2073-4441. ; 15:20
-
Tidskriftsartikel (refereegranskat)abstract
- Although the failure of a concrete dam is a complex and highly dynamic process, the current safety assessments of concrete gravity and buttress dams rely on a simplified 2D stability analysis, which neglects the load redistribution due to 3D monolith interactions and the valley shape. In addition, the estimation of breach parameters in concrete dams is based on assumptions rather than analyses, and better prediction methods are needed. Model tests have been conducted to increase the understanding of the failure behavior of concrete dams. A scale model buttress dam, with a scale of 1:15, consisting of 5 monoliths that were 1.2 m in height and 4 m in width, was constructed and loaded to failure using water pressure. The model dam had detachable abutment supports and shear keys to permit variations in the 3D behavior. The results showed that the shear transfer was large between the monoliths and that the failure of a single dam monolith is unlikely. A greater lateral restraint gives not only a higher failure load but also a better indication of impending failure. These findings suggest that the entire dam, including its boundary conditions, should be considered during a stability assessment. The results also suggest that the common assumption in dam safety codes that a single monolith fails during flooding analysis is not conservative. The dataset obtained provides a foundation for the future development of dam-monitoring alarm limits and for predictive models of dam-breaching processes.
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| 32. |
- Enzell, Jonas, et al.
(författare)
-
Realistic numerical simulations of concrete dam failures
- 2023
-
Konferensbidrag (refereegranskat)abstract
- Dam failures may have catastrophic consequences, including the release of largeamounts of water, significant property damage, and loss of life. However, safety assessments ofconcrete gravity and buttress dams often rely on simplified methods that do not consider the interactionbetween monoliths, the shape of the foundation or the presence of stiff abutments. Numericalmodeling can be a valuable tool for analyzing the stability of these dams, but it can bedifficult to validate these models due to a lack of documented dam failures. This paper presentsthe results of a numerical study examining the ability of dynamic finite element analyses to simulatedam failures. The study used the results from a series of physical model tests as a case studyfor validation. It was found that the numerical model was able to accurately reproduce the failuremode and breach development observed in the physical model tests and capture the effect of theloading rate on the failure mode and time for the failure to develop. Simulations were also performedin prototype scale to verify that the model tests were representative of a real dam failure.Further research is needed to determine the reliability of the numerical models under differentloading conditions and in realistic geological settings. However, these findings suggest that numericalmodeling can be a valuable tool for analyzing the stability of concrete gravity and buttressdams and predicting the development of failures.
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| 33. |
- Enzell, Jonas
(författare)
-
Toward Realistic Failure Evaluations for Concrete Buttress Dams
- 2023
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Concrete dams, complex structures supporting massive loads, have traditionally been assessed using simplified 2D analytical stability analyses based on the rigid body assumption. Previous studies have shown that 3D behavior, such as the interaction between the monoliths and the valley's geology, can greatly impact the load-bearing capacity of gravity dams but remains largely unexplored in buttress dams. Internal failure modes have also been shown to impact the load-bearing capacity and failure modes of concrete dams. The dam breach geometry and breach development time are important factors for flooding simulations used for emergency plans. There are no available methods for estimating the breach parameters for concrete dams. Instead, they are usually assumed based on simplified national recommendations, which introduces large uncertainties in the analysis. Thus, developing methods to estimate failure behavior in concrete gravity and buttress dams could significantly enhance flood simulation accuracy.This licentiate thesis aims to develop more realistic analysis methods for determining the load-bearing capacity and failure behavior of concrete buttress dams. To achieve this aim, studies using physical model tests were conducted to determine the 3D effects of the boundary conditions and the interaction between the monoliths and verify the results from finite element simulations. Numerical studies were performed to examine the failure behavior of concrete buttress dams and to determine suitable methods for such simulations. The results from the physical model tests suggest that 3D effects significantly impact the load-bearing capacity and the failure behavior of concrete buttress dams. Therefore, the entire dam should be considered in stability analyses rather than just single monoliths. The numerical studies showed that finite element models could successfully simulate dam failures, including the 3D behavior of concrete buttress dams and internal failure modes. However, there remain questions about the best methods for representing phenomena such as first-order roughness, valley shape, and fracture planes in these models.The model tests showed that while dam failures can occur abruptly with little to no initial signs of displacement, the presence of rough foundations, cohesion, and rock-strengthening measures in real-world dams suggests actual dam failures may not be as sudden. The results helped establish knowledge in the field to potentially create better alarm limits for automatic monitoring systems.
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| 34. |
- Erdal, Suvar, et al.
(författare)
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High frequency performance of SiGeCHBTs with selectively & non-selectively grown collector
- 2004
-
Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T114, s. 138-141
-
Tidskriftsartikel (refereegranskat)abstract
- Two high-frequency heterojunction bipolar transistor (HBT) architectures based on SiGeC have been fabricated and characterized. Different collector designs were applied either by using selective epitaxial growth doped with phosphorous or by non-selective epitaxial growth doped with arsenic. Both designs have a non-selectively deposited SiGeC base doped with boron and a poly-crystalline emitter doped with phosphorous. Both HBT designs exhibit similar electrical characteristics with a peak DC current gain of around 1600 and a BVCEO of 1.8V. The cut-off frequency (f(T)) and maximum frequency of oscillation (f(max)) vary from 40-80 GHz and 15-30 GHz, respectively, depending on lateral design relations. Good high frequency performance for a device with a selectively grown collector is demonstrated for the first time.
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| 35. |
- Eriksson, Daniel, 1987-
(författare)
-
Multiphase models for freeze-thaw actions and mass transport in concrete hydraulic structures
- 2021
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A crucial task for civil engineers is to make appropriate designs of new concrete structures and assessments of existing structures to ensure a long service life and sustainable use of the infrastructure. This doctoral thesis aims to increase the understanding of how advanced mathematical models can be used to describe phenomena and processes governing concrete degradation and thereby ultimately contribute to improving tools for design and assessments. The focus is on degradation processes that cause commonly observed concrete damage types in hydraulic structures exposed to cold climates and soft water. During a structure's service life, it is subjected to various deteriorating actions, but for the typical exposure conditions considered in this work, degradation due to freeze-thaw exposure and calcium leaching is of particular concern for the durability. Hence, the work related to improved modelling has been focused on phenomena related to these two degradation processes of concrete and how they may interact to produce damaging synergy effects.All developed models in this doctoral project treat concrete as a multiphase porous medium and use poromechanics to describe the coupled hygro-thermo-mechanical behaviour of the material. Moreover, since the overall aim concerns degradation in hydraulic structures, the model development has focused on obtaining formulations applicable for structural-scale simulations. The models presented in this thesis describe long-term water absorption into air-entrained concrete and the response of partially saturated air-entrained concrete exposed to freeze-thaw conditions. In the latter models, the phase changes and the freeze-thaw hysteresis are explicitly considered in the formulations. The presented simulation examples are performed using the Finite Element Method (FEM), and the capabilities of the models are verified with experimental data from the literature. Additionally, accelerated leaching experiments on air-entrained concrete are presented, where the influence of leaching on the formation and melting of ice inside the pore space due to pore structure alternations are investigated.The main research contribution of this work is the development and evaluation of advanced models applicable for structural-scale simulations that describe essential processes and phenomena related to freeze-thaw exposure of air-entrained concrete. The experimental work shows the significant influence of calcium leaching on the freeze-thaw processes, and the results can also facilitate future development of models considering some of the interactions causing damaging synergy effects. Adopting a multiphase modelling approach has been found suitable for describing the coupled processes and including interactions between different deterioration mechanisms. The theoretical models can also help gain further insights and improve the understanding of the phenomena, and thus, e.g. aid in developing more simplified models suited for daily engineering applications.
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| 36. |
- Eriksson, Daniel, 1987-
(författare)
-
Numerical models for degradation of concrete in hydraulic structures due to long-term contact with water
- 2018
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The durability of concrete is of major concern in all types of concrete structures where the combined effect of exposure conditions and the type and quality of the concrete material usually determines the rate of degradation. Furthermore, there are synergy effects between different deterioration mechanisms, which means that the combined rate of degradation is higher than the sum of the individual rates of each mechanism. Therefore, to accurately predict the residual service life of existing structures or when designing new structures, it is essential to consider all these aspects. This means that various chemical and physical processes, as well as how these interact, must be taken into account in models aiming to be used for service life predictions.This thesis presents the first part of a research project with the aim to investigate common deterioration mechanisms of concrete in hydraulic structures, and to improve the knowledge how these and other related phenomena can be described using mathematical models. The objective is also to study how different mechanisms interact and to find suitable approaches to account for these interactions in the models. To this end, a literature survey on commonly detected damage in hydraulic structures is presented. In addition, it also addresses in what types of and where in hydraulic structures the various damage types are usually observed. The mathematical models presented in this part of the project are focused on long-term water absorption in air-entrained concrete as well as on freezing of partially saturated air-entrained concrete. Both models are based on a multiphase description of concrete and poromechanics to describe the coupled hygro-thermo-mechanical behaviour. The thesis also presents some of the basic concepts of multiphase modelling of porous media, including discretization of the models using the finite element method (FEM). Furthermore, it covers the simplifications that are usually introduced in the general macroscopic balance equations for mass, energy and linear momentum when modelling cement-based materials.To verify the developed models and to show their capabilities, simulation results are compared with experimental data, in situ measurements and other simulations from the literature. The results indicate that both models perform well and can be used to predict long-term moisture conditions in hydraulic structures as well as freezing-induced strains in partially saturated air-entrained concrete, respectively. Even though no interactions with other deterioration mechanisms are included in the models, the development and use of these have given insights to which parameters that are important to consider in such extensions. Furthermore, based on the insights gained, the complexity of describing the full interactions between several mechanisms in mathematical models is also discussed. It is concluded that models aiming to be used for service life predictions of hydraulic structures in day-to-day engineering work need to be simplified. However, the type of advanced models presented in this thesis can serve as a basis to study which aspects and parameters that are essential to consider in simplified prediction models.
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| 37. |
- Flöistrup, Erik, et al.
(författare)
-
Synthesis of estradiol backbone mimics via the Stille reaction using copper(II) oxide as co-reagent
- 2011
-
Ingår i: Tetrahedron Letters. - : Elsevier BV. - 0040-4039 .- 1359-8562. ; 52:2, s. 209-211
-
Tidskriftsartikel (refereegranskat)abstract
- Sterically hindered biaryls and 2-phenylbenzo[b]thiophenes that can serve as templates for mimics of the estradiol backbone were prepared in modest to good yields by the Stille reaction using CuO as a co-reagent. Due to the neutral conditions applied in the Stille reaction, protection strategies were unnecessary for hydroxy containing coupling partners. Ligandless coupling conditions were also evaluated.
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| 38. |
- Fredriksson, Anna, 1979-, et al.
(författare)
-
Technology transfer as apart of the business : Inter-organizational transfer strategies based on experiences of aircraft production
- 2019
-
Ingår i: Journal of Global Operations and Strategic Sourcing. - : Emerald Group Publishing Limited. - 2398-5364 .- 2398-5372. ; 12:1, s. 151-171
-
Tidskriftsartikel (refereegranskat)abstract
- PurposeThe purpose of this paper is through a literature study and a study of the Saab offset cases to identify strategies to increase inter-organizational transfer capability.Design/Methodology/ApproachBased on a literature study and a study of three of Saab’s offset cases and Saab’s process for technology transfer.FindingsThis study has identified inter-organisational transfer strategies based on the importance of the hierarchy of decision-making and the change from capacity transfers to capability transfers in offset business. 1) The type of performance goals set in the business agreement decides how to realise the transfer. 2) The hierarchy of decision-making create a need to align the understanding of the performance goals between the different parts of the organisation, which affect the plans for how to transfer knowledge between the organizational as well as the individual levels. 3) To reach the performance goals of the technology transfer there need to be a balance between the disseminative capability of the sender and the absorptive capability of the receiver. LimitationsThis study is based on a single case within a relatively unique industry with an offset perspective and production transfers. Therefore, there is also a need for future studies to confirm the identified relationships within outsourcing/offset within other industries and other types of transfers.Originality/value: A change from capacity transfers to capability transfers in both outsourcing/offshoring and offset business indicates that more research should be placed on the disseminative capacity of the sender. The literature review revealed that the disseminative capacity of the sender has been the subject of less research than the absorptive capacity of the receiver.
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| 39. |
- Gasch, Tobias
(författare)
-
Concrete as a multi-physical material with applications to hydro power facilities
- 2016
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During its lifetime, a concrete structure is subjected to many different actions, ranging from mechanical loads to environmental actions. To accurately predict its integrity from casting and throughout its service life, a modelling strategy is required that considers mechanical loading but also implicitly accounts for physical effects such as temperature and moisture variations. This is especially true for large concrete structures found in many infrastructure applications such as bridges, nuclear power plants and dams. Modelling concrete as a multi-physical material is becoming an increasingly used approach for which large research efforts are being made, including the development of more refined mathematical and numerical methods as well as considering more physical and chemical variables in the coupled model.The research project, of which this licentiate thesis is the first phase, aims at investigating aging concrete structures at hydro power facilities, with focus on the internal structures of the power plants. This thesis presents a review of advanced mathematical methods and concepts for modelling aging concrete found in the literature which can later be applied to study such structures. The focus is on models that describe the deformational behaviour of concrete where aspects such as aging, cracking, creep and shrinkage are investigated. However, in order to accurately describe such phenomena, a multi-physical approach is adopted where moisture and temperature variations in the concrete are studied. Also, models that describe the chemical behaviour related to hydration and thus in extension aging, are also reviewed and introduced in the multi-physical framework. The use of such models are discussed in the context of the finite element method (FEM), in which coupled models are implemented, verified and applied in the appended papers using two different FE codes.Several verification examples are presented covering different aspects of the implemented models, both in isolation and coupled in a multi-physical setting. By comparing the numerical results with experimental data from the literature it can be shown that it is possible to predict most aspects of aging concrete that have been of interest here. While these examples are all on a laboratory scale, numerical examples and case studies are also provided that exemplify how the models can be applied on a structural scale. By using the developed analysis tools, valuable information and insights can be gained on aging concrete structures and these tools will in the next phase of the research project be applied to large concrete structures at hydro power facilities.
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| 40. |
- Gasch, Tobias
(författare)
-
Multiphysical analysis methods to predict the ageing and durability of concrete
- 2019
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With the societal demand for sustainability and the increasing age of infrastructure, a crucial task for the civil engineering community is to improve the durability of concrete structures. This thesis aims to contribute to such development through theoretical studies using mathematical modelling and numerical simulations. During its service life, a concrete structure is subjected to many different actions, ranging from mechanical loads to chemical and physical processes. Hence, a sound modelling strategy requires multiphysics and the inclusion of coupled chemical and physical fields (e.g. temperature, moisture and cement hydration) in addition to methods that describe mechanical integrity of the material. Conditions and phenomena critical for concrete structures at hydropower facilities have been of particular interest to study.The thesis presents several mathematical models of various complexity to describe the multiphysical behaviour of concrete using a material point description. A significant focus is on models that describe the mechanical behaviour of concrete where aspects such as ageing, cracking, creep and shrinkage are investigated. For the creep behaviour, a state-of-the-art model based on the Microprestress–Solidification (MPS) theory is reviewed and further developed. The appended papers (III to IV) presents a mathematical framework for the modelling of durability aspects of concrete based on multiphase porous media theory. The governing equations are derived with the Thermodynamically Constrained Averaging Theory (TCAT) as a starting point. It is demonstrated how this framework can be applied to a broad variety of phenomena related to durability; from the casting and hardening of concrete to the long-term absorption of water into air-entrained concrete. The Finite Element Methods (FEM) is used to solve the proposed mathematical models, and their capabilities are verified using experimental data from the literature.The main research contribution is the development and evaluation of theoretical models that advance the understanding and improve knowledge of the ageing and durability of concrete and concrete structures. More precisely, it is shown how multiphysical models and the developed multiphase framework can be used to gain insights on the material behaviour of concrete at smaller scales while they are also applicable to structural-scale simulations. During all model development, the efficient solution of structural problems has been fundamental. Through case studies and several examples from the literature, it is exemplified how these models can be used to enhance the performance and thereby increase the durability of concrete structures.
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| 41. |
- Gasch, Tobias, et al.
(författare)
-
Non-linear analyses of cracks in aging concrete hydro power structures
- 2016
-
Ingår i: Dam Engineering. - : International Water Power & Dam Construction. - 0958-9341.
-
Annan publikation (populärvet., debatt m.m.)abstract
- The concrete structures at Swedish hydro power facilities were built during the early to mid-20th century and many of them are starting to exhibit age related wear and deterioration. It isimportant to ensure the integrity of these concrete structures from a dam safety perspectiveand also to secure a safe operation of the power facility in the future. With the latter in mind,this paper aims to study the concrete structures that house the power generating machinery ofthe facility, especially the parts close to the generator where the loads from the power unit aresupported. Cracks observed in these structures will reduce its stiffness, which affects theoperation of the rotating machinery. This paper presents and discusses some generalconsiderations and loads that are of importance for this type of structures and highlights sometypical cracks that have been observed in Swedish hydro power facilities. To complement thisdiscussion, a case study is presented of a hydro power facility where cracks have been foundin the concrete support structure of the power unit, especially at the interconnections betweenthe unit and the concrete. The most likely cause of these cracks are investigated through nonlinearfinite element analysis considering mechanical loads as well as physical loads such asdrying shrinkage and temperature variations. It is concluded that the long-term physicalloading is the most probable cause of the observed cracks. However, the operation of thepower unit and changes in its operational pattern can cause further propagation of thesecracks. Finally, suggestions on possible enhancement of the analysis methods used in the casestudy are proposed and discussed for further studies of this type of concrete structures.
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| 42. |
- Haralson, Erik, et al.
(författare)
-
Device design for a raised extrinsic base SiGe bipolar technology
- 2004
-
Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 48:11-okt, s. 1927-1931
-
Tidskriftsartikel (refereegranskat)abstract
- The impact of emitter, inside spacer, and SIC lateral scaling on the AC and DC performance of a raised extrinsic base SiGe HBT has been investigated using the ISE TCAD simulation package and design of experiments methods. Strong first order effects for all three variables were observed while the interactions of the variables had a weaker effect. It was found that as the emitter size shrinks towards 0.1 mum the impact of changes to inside spacer and SIC width on the current gain increased. The response surface design led to an optimized simulated transistor featuring f(T) and f(MAX) values of 214 and 332 GHz, respectively.
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| 43. |
- Haralson, Erik, et al.
(författare)
-
HRXRD analysis of SiGeC layers for BiCMOS applications
- 2004
-
Konferensbidrag (refereegranskat)abstract
- The use of HRXRD for the monitoring of the dopant activation anneal through the detection of carbon outdiffusion has been demonstrated. The advantages of HRXRD over other measurement techniques for in-line epi-growth monitoring are also discussed. HRXRD reciprocal space mapping was used to study the SiGe layer stability as a function of carbon concentration for vertically scaled layers designed for high performance BiCMOS applications. It was found that as the carbon concentration is increased there is a reduction of boron cluster formation, but an increase in defect density is also observed.
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| 44. |
- Haralson, Erik, et al.
(författare)
-
Influence of self heating in a BiCMOS on SOI technology
- 2004
-
Ingår i: ESSCIRC 2004. - NEW YORK : IEEE. - 0780384784 ; , s. 337-340
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Konferensbidrag (refereegranskat)abstract
- Self heating in a 0.25mum BiCMOS technology with different isolation structures is characterized. Thermal resistance values for single- and multiple-emitter devices are extracted and reported. The dependence of the thermal resistance on the emitter aspect ratio is critical to take into consideration when determining the isolation scheme for devices. 2-D electro-thermal simulations are performed and compared to experimental results. The impact of metallization on the self-heating in the device is examined through simulations.
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| 45. |
- Haralson, Erik, et al.
(författare)
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NiSi integration in a non-selective base SiGeCHBT process
- 2005
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 8:03-jan, s. 245-248
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Tidskriftsartikel (refereegranskat)abstract
- A self-aligned nickel silicide (salicide) process is integrated into a non-selective base SiGeC HBT process. The device features a unique, fully silicided base region that grows laterally under the emitter pedestal. This Ni(SiGe) formed in this base region was found to have a resistivity of 23-24 muOmega cm. A difference in the silicide thickness between the boron-doped SiGeC extrinsic base region and the in situ phosphorous-doped emitter region is observed and further analyzed and confirmed with a blanket wafer silicide study. The silicided device exhibited a current gain of 64 and HF device performance of 39 and 32 GHz for f(t) and f(MAX), respectively.
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| 46. |
- Haralson, Erik, et al.
(författare)
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The effect of C on emitter-base design for a single-polysilicon SiGe : C HBT with an IDP emitter
- 2004
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 224:1-4, s. 330-335
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Tidskriftsartikel (refereegranskat)abstract
- A differential epitaxy SiGe:C heterojunction bipolar junction transistor (HBT) design is reported and used to study the effect of carbon on junction formation as well as the effect of lateral design parameters on ac and dc performance. The device exhibits a high current gain (beta) of 1700 and a BVCEO of 1.8 V. The peak cutoff frequency (f(T)) and maximum oscillation frequency (f(MAX)) are 73 and 17 GHz, respectively. The effect of emitter overlap on f(T) was minimal, but it had a strong impact on dc performance. LOCOS opening size strongly impacted both ac and dc performance. In addition, the effect of carbon, base cap thickness, and rapid thermal anneal (RTA) temperature on the emitter-base (E-B) junction formation was studied.
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| 47. |
- Hassanzadeh, Manouchehr, et al.
(författare)
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Analysis of Displacements and Crack Formations in Foundations for Hydropower Generators
- 2012
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Konferensbidrag (refereegranskat)abstract
- A rather extensive program for improvement of the Swedish hydropower plants is ongoing. The aims are to secure future production and to maintain and further develop an already high dam safety. In connection with earlier work, which dealt with assessment of an existing buttress dam where a non-linear finite element model was applied to determine the cause of the observed cracks. The results showed that the non-linear finite element method is a powerful tool to determine the structural behaviour of large concrete structures. The study in this paper is a continuation of the previous project, aiming at applying the method to other parts of dam structure such as foundation supporting the generator (stator and rotor), rotor spider, turbine shaft, spiral casing, turbine and draft tube.The hydropower plant, which is studied, was constructed in the early forties. During the inspection, structural damages (cracks) were discovered around some of the stator and rotor spider supports. The cracks were believed to be related to the function of the stator supports and to new patterns of generator operation. In earlier times, the generators ran continuously, while nowadays there are many stops and starts, some times even several times during one day. The purpose of this study is to illuminate the complex stress conditions in the generator foundations of a hydropower plant and to reveal the causes of the stresses and to verify their role in formation of the cracks.The structural behaviour of a foundation has been analysed taking into account the transient thermal gradients in combination with dead loads and some of the operational loads imposed to the foundation. A three dimensional non-linear finite element model has been applied in order to analyse formation and propagation of the cracks. The analyses showed that based on the assumption made, the concrete foundation cracks mainly on the outside but also near some of the stator supports due to the combination of mechanical and thermal loads. However, the studied loads cannot explain all of the types of damages that can be found in-situ. It is likely that especially the drying shrinkage may be the one of the reasons for the cracks that has been found near the stator supports and especially the rotor spider supports.It is important from a dam safety perspective to determine the causes of the structural cracks that have been found in-situ and also to evaluate the effect of the reduced stiffness due to cracking, since a reduced structural stiffness can result in larger loads imposed on the structure from the magnetic eccentricity and turbine imperfections or alternatively lead to a fatigue failure of for instance the reinforcement.
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| 48. |
- Hedberg, Berith, 1951-, et al.
(författare)
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Factors associated with confidence in decision making and satisfaction with risk communication among patients with atrial fibrillation
- 2018
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Ingår i: European Journal of Cardiovascular Nursing. - : Sage Publications. - 1474-5151 .- 1873-1953. ; 17:5, s. 446-455
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Atrial fibrillation is a prevalent cardiac arrhythmia. Effective communication of risks (e.g. stroke risk) and benefits of treatment (e.g. oral anticoagulants) is crucial for the process of shared decision making.AIM: The aim of this study was to explore factors associated with confidence in decision making and satisfaction with risk communication after a follow-up visit among patients who three months earlier had visited an emergency room for atrial fibrillation related symptoms.METHODS: A cross-sectional design was used and 322 patients (34% women), mean age 66.1 years (SD 10.5 years) with atrial fibrillation were included in the south of Sweden. Clinical examinations were done post an atrial fibrillation episode. Self-rating scales for communication (Combined Outcome Measure for Risk Communication and Treatment Decision Making Effectiveness), uncertainty in illness (Mishel Uncertainty in Illness Scale-Community), mastery of daily life (Mastery Scale), depressive symptoms (Hospital Anxiety and Depression Scale) and vitality, physical health and mental health (36-item Short Form Health Survey) were used to collect data.RESULTS: Decreased vitality and mastery of daily life, as well as increased uncertainty in illness, were independently associated with lower confidence in decision making. Absence of hypertension and increased uncertainty in illness were independently associated with lower satisfaction with risk communication. Clinical atrial fibrillation variables or depressive symptoms were not associated with satisfaction with confidence in decision making or satisfaction with risk communication. The final models explained 29.1% and 29.5% of the variance in confidence in decision making and satisfaction with risk communication.CONCLUSION: Confidence in decision making is associated with decreased vitality and mastery of daily life, as well as increased uncertainty in illness, while absence of hypertension and increased uncertainty in illness are associated with risk communication satisfaction.
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| 49. |
- Hellgren, Rikard, 1988-
(författare)
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A systems approach to ice loads on concrete dams
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dams are mainly used for the storage of water to electricity production and irrigation, or for river regulation. Continuous work to assure a high dam safety level is a prerequisite to minimize the risk for the uncontrolled release of water. An essential part of the safety evaluation of concrete dams is to understand the loads they are exposed to and the expected response of the dam. Under normal conditions, the behaviour of concrete dams is, to a great extent, governed by the ambient variation in temperature and water level. For concrete dams in cold climates, the large variation in ambient temperatures between summer and winter is particularly significant. In addition, these dams may be subjected to a pressure load from the expansion or movement of an ice sheet on the reservoir. The current guidelines for these ice loads are based on the dam's location and state that concrete dams must be designed for a line load of 50-250 kN/m. Thus, the ice load constitutes a significant part of the total load, especially for small dams. Despite its relatively significant impact, the knowledge about ice loads is insufficient, and the magnitude and return period of ice loads constitute one of the greatest uncertainties during stability evaluations of concrete dams. Furthermore, an apparent contradiction is that measurements and models indicate that ice loads are higher than the recommended values. Simultaneously, there are no reported dam failures where the ice-load has been addressed as the reason for the breach.To increase the knowledge about ice loads and the structural behaviour of concrete dams, this thesis applies an approach where the ice and the dam are parts of a structural system. The thesis contains six studies investigating the dam's, the ice's or the system's response to external loads. Studies of the dam are aimed at increasing the understanding of the normal behaviour of concrete dams. Studies of ice loads include measurements, and a major contribution from this project is the development of a 1$\times$3 m$^2$ ice load panel, the installation of the panel on a concrete dam, and subsequent measurements during six winters. In addition, a systematic review and meta-analysis of previous measurements have been performed. The studies of the different parts have been connected through two studies of the entire system. The first is a parameter study where the static interaction between ice and dam is simulated to quantify how geometric variations of the reservoir and ice affect the mechanical ice loads. The second study searches for detectable influence from the ice load in the measured behaviour of concrete dams.The results show that the structural behaviour of concrete dams under normal conditions is primarily governed by the variation in water level and temperature. For the studied dams, these effects are significantly larger than the influence from damage and degradation. Ice load measurements and simulations show that ice loads varies significantly along the dam. This variation makes it difficult to quantify the impact of external factors on the magnitude of ice loads. Despite this difficulty, three independent analyses show that ice thickness, water level change, and the dam's properties have an evident effect on the magnitude of ice loads. If current guidelines are to be updated to consider local conditions at the dam, these three parameters should be included. Ice loads of the magnitudes measured and specified in the current guidelines should have a notable impact on the behaviour of a dam during normal operation. However, such an impact has not been found in the eight dams studied within this project. This result indicates that the ice loads measured locally do not necessarily represent the global ice load that acts on the entire structure.
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| 50. |
- Hellgren, Rikard, 1988-, et al.
(författare)
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Estimating the ice loads on concrete dams based on their structural response
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- In the assessment of concrete dams in cold climate, it is common that the theoretical stability becomes insufficient for load cases that includes ice loads. However, the magnitude and return period of these ice loads have a high degree of uncertainty. This study estimates the magnitude of ice loads on eight concrete dam monoliths using measurements of their displacement from 29 winters. In the displacement signals, events are identified and assumed to be caused solely by ice loads. The observed displacement during an event is interpreted as an ice load using a load-displacement relationship derived from FE simulations of each dam. These simulations show that ice loads of the magnitudes given in design guidelines and recorded in previous measurements would significantly affect the structural response of the studied dams. However, only small traces of ice loads can be found in the observed responses of the studied dams. The estimated ice loads are significantly lower than the ice loads recorded in traditional ice load measurements. These results indicate that the average magnitude of ice load on an entire monolith is significantly lower than the measured local pressures. This would imply that ice loads may be a smaller concern regarding the dam safety than previously believed.
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