| 11. |
- Boyle, P, et al.
(författare)
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Need for global action for cancer control
- 2008
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Ingår i: Annals of oncology : official journal of the European Society for Medical Oncology. - : Elsevier BV. - 1569-8041. ; 19:9, s. 1519-1521
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 12. |
- Ergun, R. E., et al.
(författare)
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Observations of Double Layers in Earth's Plasma Sheet
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:15, s. 155002-
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Tidskriftsartikel (refereegranskat)abstract
- We report the first direct observations of parallel electric fields (E-parallel to) carried by double layers (DLs) in the plasma sheet of Earth's magnetosphere. The DL observations, made by the THEMIS spacecraft, have E-parallel to signals that are analogous to those reported in the auroral region. DLs are observed during bursty bulk flow events, in the current sheet, and in plasma sheet boundary layer, all during periods of strong magnetic fluctuations. These observations imply that DLs are a universal process and that strongly nonlinear and kinetic behavior is intrinsic to Earth's plasma sheet.
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| 13. |
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| 14. |
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| 15. |
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| 16. |
- Agardh, E.E, et al.
(författare)
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Socio-economic position at three points in life in association with type 2 diabetes and impaired glucose tolerance in middle-aged Swedish men and women
- 2007
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Ingår i: International Journal of Epidemiology. - : Oxford University Press (OUP). - 0300-5771 .- 1464-3685. ; 36:1, s. 84-92
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundIt has been suggested that low socio-economic position(SEP) during childhood and adolescence predicts risk of adulttype 2 diabetes. We investigated the associations between type2 diabetes and childhood SEP (fathers’ occupational position),participants’ education and adult SEP (participants’occupational position). To determine possible independent associationsbetween early SEP (fathers’ occupational position andparticipants’ education) and disease, we adjusted foradult SEP and factors present in adult life associated withtype 2 diabetes. MethodsThis cross-sectional study comprised 3128 men and 4821women aged 35–56 years. All subjects have gone througha health examination and answered a questionnaire on lifestylefactors. At the health centre, an oral glucose tolerance testwas administered and identified 55 men and 52 women with previouslyundiagnosed type 2 diabetes. Relative risks (RRs) with 95% CIswere calculated in multiple logistic regression analyses. ResultsThe age-adjusted RRs of type 2 diabetes if having afather with middle occupational position were 2.3 [Confidenceinterval (CI:1.0–5.1) for women and, 2.0 (CI:0.7–5.6)for men]. Moreover, low education was associated with type 2diabetes in women, RR = 2.5 (CI:1.2–4.9). Low occupationalposition in adulthood was associated with type 2 diabetes inwomen, RR = 2.7 (CI:1.3–5.9) and men, RR = 2.9 (CI:1.5–5.7).The associations between early SEP and type 2 diabetes disappearedafter adjustment for adult SEP and factors associated with type2 diabetes. ConclusionThe association between type 2 diabetes and low SEPduring childhood and adolescence in middle-aged Swedish subjectsdisappeared after adjustment for adult SEP and adult risk factorsof diabetes.
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| 17. |
- Andersson, David A., et al.
(författare)
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Modeling of Ce2, Ce2O3 ,and CeO2-x in the LDA+U formalism
- 2007
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 75, s. 035109-1-035109-6
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure and thermodynamic properties of CeO2 and Ce2O3 have been studied from first principles by the all-electron projector-augmented-wave (PAW) method, as implemented in the ab initio total-energy and molecular-dynamics program VASP (Vienna ab initio simulation package). The local density approximation (LDA)+U formalism has been used to account for the strong on-site Coulomb repulsion among the localized Ce 4f electrons. We discuss how the properties of CeO2 and Ce2O3 are affected by the choice of U as well as the choice of exchange-correlation potential, i.e., the local density approximation or the generalized gradient approximation. Further, reduction of CeO2, leading to formation of Ce2O3 and CeO2-x, and its dependence on U and exchange-correlation potential have been studied in detail. Our results show that by choosing an appropriate U it is possible to consistently describe structural, thermodynamic, and electronic properties of CeO2, Ce2O3, and CeO2-x, which enables modeling of redox processes involving ceria-based materials.
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| 18. |
- Andersson, David A., et al.
(författare)
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Optimization of ionic conductivity in doped ceria
- 2006
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 103:10, s. 3518-3521
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Tidskriftsartikel (refereegranskat)abstract
- Oxides with the cubic fluorite structure, e.g., ceria (CeO2), are known to be good solid electrolytes when they are doped with cations of lower valence than the host cations. The high ionic conductivity of doped ceria makes it an attractive electrolyte for solid oxide fuel cells, whose prospects as an environmentally friendly power source are very promising. In these electrolytes, the current is carried by oxygen ions that are transported by oxygen vacancies, present to compensate for the lower charge of the dopant cations. Ionic conductivity in ceria is closely related to oxygen-vacancy formation and migration properties. A clear physical picture of the connection between the choice of a dopant and the improvement of ionic conductivity in ceria is still lacking. Here we present a quantum-mechanical first-principles study of the influence of different trivalent impurities on these properties. Our results reveal a remarkable correspondence between vacancy properties at the atomic level and the macroscopic ionic conductivity. The key parameters comprise migration barriers for bulk diffusion and vacancy-dopant interactions, represented by association (binding) energies of vacancy-dopant clusters. The interactions can be divided into repulsive elastic and attractive electronic parts. In the optimal electrolyte, these parts should balance. This finding offers a simple and clear way to narrow the search for superior dopants and combinations of dopants. The ideal dopant should have an effective atomic number between 61 (Pm) and 62 (Sm), and we elaborate that combinations of Nd/Sm and Pr/Gd show enhanced ionic conductivity, as compared with that for each element separately.
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| 19. |
- Andersson, David A., et al.
(författare)
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Redox properties of CeO2-MO2 MO2 (M=Ti, Zr, Hf or Th) solid solutions from first principles calculations
- 2007
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 90:3, s. 031909-
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Tidskriftsartikel (refereegranskat)abstract
- The authors have used density functional theory calculations to investigate how the redox thermodynamics and kinetics of CeO2 are influenced by forming solid solutions with TiO2, ZrO2, HfO2, and ThO2. Reduction is facilitated by dissolving TiO2 (largest improvement), HfO2, or ZrO2 (least improvement), while ThO2 makes reduction slightly more difficult. The migration barrier is much lower in the neighborhood of a Ti (largest decrease), Hf, or Zr (least decrease), while the binding energy of solute ions and vacancies increases in the same sequence. They rationalize the properties of ceria solid solutions in terms of defect cluster relaxations.
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| 20. |
- Andersson, David A., et al.
(författare)
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Theoretical study of CeO(2) doped with tetravalent ions
- 2007
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Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 76, s. 1741191-17411910
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Tidskriftsartikel (refereegranskat)abstract
- We have used density functional theory calculations within the LDA+U formulation to investigate how small amounts of dissolved SiO2, GeO2, SnO2, or PbO2 affect the redox thermodynamics of ceria (CeO2). Compared to pure ceria, reduction is facilitated and the reducibility increases in the sequence of CeO2-SnO2, CeO2-GeO2, and CeO2-SiO2, which correlates with the decrease of the ionic radii of the solutes. For low solute concentrations, there is an inverse relation between high reducibility and the solution energy of tetravalent solutes. CeO2-PbO2 is unique in the sense that the initial reduction occurs by Pb(IV)double right arrow Pb(II) instead of the usual Ce(IV)double right arrow Ce(III) reaction. Among the investigated ceria compounds, CeO2-PbO2 has the lowest reduction energy and rather low solution energy. We have studied how the solution and reduction energies depend on the concentration of Si, Ge, Sn, Pb, Ti, Zr, Hf, and Th solute ions. While the solution energy increases monotonously with concentration, the reduction energy first decreases, as compared to pure ceria (except for Th, which exhibits a small increase), and with further increase of solute concentration, it either remains almost constant (Zr, Hf, and Th) or slightly increases (Ti, Si, Ge, and Sn).
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