| 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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