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- Engström, Carl-Peter, 1945, et al.
(författare)
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Health-related quality of life in COPD: why both disease-specific and generic measures should be used.
- 2001
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Ingår i: The European respiratory journal : official journal of the European Society for Clinical Respiratory Physiology. - 0903-1936. ; 18:1, s. 69-76
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Tidskriftsartikel (refereegranskat)abstract
- Although research has consistently demonstrated that chronic obstructive pulmonary disease (COPD) impairs health-related quality of life (HRQL), little agreement has been evidenced regarding the factors identified as contributing to impaired HRQL. The aim was to study such factors using well established generic and specific HRQL instruments. The patients (n=68) were stratified by forced expiratory volume in one second (FEV1) to represent a wide range of disease severity. Pulmonary function, blood gases and 6-min walking distance test (6MWD) were assessed. HRQL instruments included: St George's Respiratory Questionnaire (SGRQ), Sickness Impact Profile (SIP), Hospital Anxiety and Depression Scale and Mood Adjective Check List. The strength of the impact of COPD on HRQL was represented along a continuum ranging from lung function, functional status (physical and psychosocial) to wellbeing. Although correlations between FEV1 versus SGRQ total and SIP overall scores (r=-0.42 and -0.32) were stronger than previously reported, multiple regression analyses showed that lung function contributed little to the variance when dyspnoea-related limitation, depression scores and 6MWD were included in the models. These three factors were important to varying degrees along the whole range of HRQL. Physiological, functional and psychosocial consequences of chronic obstructive pulmonary disease are only poorly to moderately related to each other. The present study concludes that a comprehensive assessment of the effects of chronic obstructive pulmonary disease requires a battery of instruments that not only tap the disease-specific effects, but also the overall burden of the disease on everyday functioning and emotional wellbeing.
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| 2. |
- Engström, Olof, 1943, et al.
(författare)
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Electron capture at InAs/GaAs quantum dots
- 2004
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Ingår i: 8th International Conference on Nanometer Scale Science and Technology, Venice, Italy, 2004.
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Konferensbidrag (refereegranskat)
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| 3. |
- Engström, Olof, 1943, et al.
(författare)
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Electron capture cross sections of InAs/GaAs quantum dots
- 2004
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 85:14, s. 2908-2910
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Tidskriftsartikel (refereegranskat)abstract
- The thermal emission rates of electrons from InAs/GaAs quantum dots were measured, to found the capture cross sections in the extremely high region of 10-11-10-10 cm2. An additional method based on a static measurement at thermal equilibrium was used where the Fermi level was positioned at the free energy level of the quantum dot s shell. A Schottky diode with a plane of QDs grown in its depletion region and back-biased in such a way that the Fermi level coincides with the electron energy level. The Fermi level passes the lowest energy level of the QD, at the voltage marked by Vp in the graphs.
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| 6. |
- Fu, Ying, 1964, et al.
(författare)
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Emission rates for electron tunneling from InAs quantum dots to GaAs substrate
- 2004
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 96:11, s. 6477-6481
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Tidskriftsartikel (refereegranskat)abstract
- Tunneling emission rates of electrons from InAs quantum dots (QD) in a GaAs matrix depletion region have been calculated for application in the analysis of experimental data from deep-level transient spectroscopy (DLTS). The hybridization among metastable states localized in the InAs QD and continuum states in the GaAs substrate in the DLTS measurement is evaluated from the local densities of states. Two physical quantities have been calculated, the broadening of the metastable state localized in the InAs QD, i.e., the charge-transfer rates from the quantum dot to the substrate, and the corresponding hybridization coefficients. The metastable state is broadened significantly only when the bias is large enough, whereas the hybridization coefficients increase almost linearly with the bias. The effects of the direct Coulomb interactions and exchange energies among electrons initially confined in the QD have been included and found to be very significant. Increasing the number of electrons initially confined in the QD from 1 to 4, the charge-transfer rates increase by a factor of 1.8.
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