| 51. |
- Århammar, Cecilia, et al.
(författare)
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Energetics and magnetic properties of V-doped MgO bulk and (001) surface : A GGA, GGA+U, and hybrid density functional study
- 2010
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 82:13, s. 134406-
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a first-principles study of the energetic and magnetic properties of V-doped MgO is presented, where both the bulk and (001) surface were investigated. It is found that V assumes a high-spin state with a local moment of about 3 mu(B). In the bulk, the interaction between these local moments is very short ranged and the antiferromagnetic (AFM) ordering is energetically more favorable. The formation of V-V-Mg-V defect clusters is found to weaken the antiferromagnetic coupling in bulk MgO, degenerating the AFM and ferro-magnetic state. However, these clusters are high in energy and will not form at equilibrium conditions. By employing the GGA+U approach, with U=5 eV, the V 3d states on the (001) surface are shifted below the Fermi level, and a reasonable surface geometry was achieved. A calculation with the hybrid HSE03 functional, contradicts the GGA+U results, indicating that the V-MgO surface should be metallic at this concentration. From the energetics it is concluded that, at the modeled concentration, VxOy phases will limit the solubility of V in MgO at equilibrium conditions, which is in agreement with previous experimental findings. In order to achieve higher concentrations of V, an off-equilibrium synthesis method is needed. Finally, we find that the formation energy of V at the surface is considerably higher than in the bulk and V is thus expected to diffuse from the surface into the bulk of MgO.
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| 52. |
- Andersson, M., et al.
(författare)
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Dynamics of entry and exit of product varieties : What evolution dynamics can account for the empirical regularities?
- 2011
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Ingår i: Nonlinear Economic Dynamics. - : Nova Science Publishers, Inc.. - 9781616687885 ; , s. 155-174
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Bokkapitel (refereegranskat)abstract
- Firm-level heterogeneity is substantial even in narrowly defined industries. This chapter focuses on formulating evolution dynamics which can account for the observed heterogeneity and its maintenance. Based on examination of data on Swedish firms' supply pattern across different markets over time, we present a parsimonious model that has the ambition to capture the picture of heterogeneous firms, while accommodating the simultaneous exit and entry of destination varieties in firms' supply pattern. The model assumes both scale economies of firms and path-dependence, where the latter is manifested in such a way that the arrival rate of innovation ideas to an individual firm is a function of each firm's stock of varieties at every given point in time. The path-dependence phenomenon is an "explosive" non-linearity, whereas conservation mechanisms include development of demand and exit of established varieties. The described path dependence explains the skewed distribution of varieties across firms. Exit of obsolete varieties and growth of demand keep the "equilibrium" away from competitive exclusion where only few large firms remain. We make use of simulations to depict and assess the innovation dynamics of the proposed model.
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| 53. |
- Andersson, Martin, et al.
(författare)
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Multinationals in the Knowledge Economy : A case study of AstraZeneca in Sweden
- 2010
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Ingår i: Repositioning Europe and America for Growth. - Berlin : LIT Verlag. - 9783643107763
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Bokkapitel (refereegranskat)abstract
- This report presents a case study of the role of a large R&D intensive multinational company for a small open economy. The case study examines the role of AstraZeneca in the Swedish economy, i.e. an economy dominated by multinational companies. The purpose of the report is to analyze the interaction of AstraZeneca’s units in Sweden with the rest of the Swedish economy, and the Swedish innovation system in particular. We analyze the company’s role as an employer in the private sector, its transaction links with other Swedish firms and its role for Sweden’s exports. In a second perspective we focus on the company’s role in the Swedish knowledge economy and innovation system. The report analyses the company as a node for knowledge flows in the Swedish economy and innovation system, and its role as an employer of highly educated and skilled workers in Sweden.Our analysis of the Swedish units’ interaction with the rest of the Swedish economy shows that ’traditional’ couplings in the form of transactions with Swedish suppliers are limited. It is instead the company’s position in the ‘knowledge economy’ that makes its presence in Sweden important.
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| 54. |
-
Entrepreneurship and regional development : Local processes and global patterns
- 2010
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Samlingsverk (redaktörskap) (refereegranskat)abstract
- 'The world is experiencing the fourth globalization trend since the collapse of the Berlin Wall twenty years ago. This trend unlike previous ones is characterized by both broader global interconnection and deeper localization. In other words, the world is both flatter and spikier at the same time. The key to a successful development policy is to integrate these two seemingly counter intuitive trends. The solution to this is a more or less regional strategy with a very strong focus on entrepreneurship. While this approach is not new and is not the first, it is the best one that I have seen. The editors of this collection are some of the best informed, most careful and deep thinking scholars in the business and have produced a work worthy of their stature.
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| 55. |
- Gorbatov, O. I., et al.
(författare)
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Vacancy-solute interactions in ferromagnetic and paramagnetic bcc iron : Ab initio calculations
- 2011
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 419:1-3, s. 248-255
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Tidskriftsartikel (refereegranskat)abstract
- Vacancy-solute interactions play a crucial role in diffusion-controlled processes, such as ordering or decomposition, which occur in alloys under heat treatment or under irradiation. Detailed knowledge of these interactions is important for predicting long-term behavior of nuclear materials (such as reactor steels and nuclear-waste containers) as well as for advancing our general understanding of kinetic processes in alloys. Using first-principles calculations based on the density functional theory and employing the locally self-consistent Green's function technique, we develop a database of vacancy-solute interactions in dilute alloys of bcc Fe with 3p (Al, Si, P, S), 3d (Sc-Cu), and 4d (Y-Ag) elements. Unrelaxed interactions within the first three coordination shells have been computed in the ferromagnetic state as well as in the paramagnetic (disordered local moment) state of the iron matrix. Magnetism is found to have a strong effect on the vacancy-solute interactions. Implications of the obtained results for interpreting the effects of vacancy trapping and enhanced impurity diffusion are discussed.
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| 56. |
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| 57. |
- Kabliman, Evgeniya, et al.
(författare)
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Ab initio-based mean-field theory of the site occupation in the Fe-Cr sigma-phase
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : AMER PHYSICAL SOC. - 1098-0121 .- 1550-235X. ; 83:9, s. 092201-
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Tidskriftsartikel (refereegranskat)abstract
- An efficient first-principles-based mean-field theory is applied to study the site occupations in the Fe-Cr sigma phase. It is based on the expansion of the total energy of a random alloy close to the equiatomic composition in the paramagnetic state in terms of the effective on-site interactions and takes into account longitudinal spin fluctuations at high temperatures. The calculated site occupation is in very good agreement with the existing experimental data.
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| 58. |
- Kabliman, Evgeniya, et al.
(författare)
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Configurational thermodynamics of the Fe-Cr sigma phase
- 2011
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 84:18, s. 184206-
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Tidskriftsartikel (refereegranskat)abstract
- Configurational thermodynamics of the Fe-Cr sigma phase is investigated on the basis of an Ising-type configurational Hamiltonian and a single-site mean-field model for the free energy. The parameters of the statistical models are obtained from efficient first-principles calculations using different computational techniques. We demonstrate that the effective pair and multisite interactions in the sigma phase are relatively small, which allows using a simplified model for distributing Fe and Cr atoms among sublattices. We also show that this system exhibits a nontrivial magnetic behavior at high temperatures, which affects the site occupation by Fe and Cr atoms. The structural variation (volume and c/a) that might be present due to neutron irradiation and thermal expansion can lead to an additional atomic redistribution.
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| 59. |
- Karlsson, Charlie, 1945-, et al.
(författare)
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Introduction
- 2010
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Ingår i: Entrepreneurship and Regional Development.. - Cheltenham : Edward Elgar Publishing. - 9781847209320 ; , s. 1-27
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Bokkapitel (refereegranskat)
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| 60. |
- Karlsson, C., et al.
(författare)
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Introduction
- 2010
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Ingår i: Entrepreneurship and Regional Development. - : Edward Elgar Publishing. - 9781847209320 ; , s. 1-27
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Bokkapitel (refereegranskat)
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