| 421. |
- Johansson, Börje, et al.
(författare)
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The analysis of location, colocation and urbanization economies
- 2008
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Ingår i: Handbook of Research on Cluster Theory. - Cheltenham, U.K. : Edward Elgar Publishing. - 9781845425166 ; , s. 39-66
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Bokkapitel (refereegranskat)abstract
- This paper provides an overview and critical assessment of co-location and clustering in space. Basic location conditions include accessibility to customers, input suppliers including knowledge providers, and regional endowments. A distinction is made between slow and fast location adjustments. In a basic model, it is shown how distance sensitivity and scale economies generate self-reinforcing location externalities. Variations of the same model are employed to illuminate how urbanisation economies can stimulate co-location and clustering. One model variant is designed to examine how innovation activities also can be influenced by urbanisation economies. The paper concludes that a set of basic principals form the basis for localisation and urbanisation economies. However, there remains a challenging gap between model predictions and empirical observations.
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| 422. |
- Johansson, Börje, 1945-, et al.
(författare)
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Time distances and labor market integration
- 2002
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Ingår i: Papers in regional science (Print). - : Wiley. - 1056-8190 .- 1435-5957. ; 81:3, s. 305-327
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Tidskriftsartikel (refereegranskat)abstract
- This article investigates how time distances within and between municipalities determine the spatial extent of local and regional labor markets. As time distances change, the extent of the labor market will also change. Diminishing time distances will bring about increases in labor market size by integrating formerly spatially separate markets. We analyze such processes using accessibility measures derived from a random choice preference function approach. Accessibility is measured in terms of number of jobs, labor supply and supply of service functions. The aim of the work is to illustrate the usefulness of the purpose-specific accessibility measure we introduce.
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| 423. |
- Johansson, Börje, et al.
(författare)
-
Time distances and labor market integration
- 2002
-
Ingår i: Papers in regional science (Print). - : Wiley. - 1056-8190 .- 1435-5957. ; 81:3, s. 305-327
-
Tidskriftsartikel (refereegranskat)abstract
- This article investigates how time distances within and between municipalities determine the spatial extent of local and regional labor markets. As time distances change, the extent of the labor market will also change. Diminishing time distances will bring about increases in labor market size by integrating formerly spatially separate markets. We analyze such processes using accessibility measures derived from a random choice preference function approach. Accessibility is measured in terms of number of jobs, labor supply and supply of service functions. The aim of the work is to illustrate the usefulness of the purpose-specific accessibility measure we introduce.
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| 424. |
- Johansson, Börje Örje, et al.
(författare)
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Theoretical study of protactinium at high pressure
- 2006
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Ingår i: Mater Res Soc Symp Proc. - 1558998470 - 9781558998476 ; , s. 255-269
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Konferensbidrag (refereegranskat)abstract
- We have studied the crystal structure of Pa metal under high pressure by means of first-principles calculations based on the density functional theory (DFT) using the generalized gradient approximation (GGA). The body centered tetragonal (bct) to orthorhombic (α-U) phase transition was calculated to take place at 29 GPa and with a volume change of 1.3%. The calculated c/a for the bet phase reaches the ideal c/a value (0.816) at around 50 GPa. A bulk modulus of 113 GPa was derived from a Murnaghan equation of state (EOS) fitting procedure. Our results are in general good agreement with recent experiment performed by Haire et al, [Phys. Rev. B 67, 134101 (2003)]. We have also calculated phonon spectra for fcc, bct and bcc Pa. The bcc spectrum gives imaginary frequencies showing the low temperature instability of this crystallographic phase for Pa.
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| 425. |
- 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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| 426. |
- 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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| 427. |
- Kadas, K., et al.
(författare)
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Surface relaxation and surface stress of 4d transition metals
- 2006
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Ingår i: Surface Science. - : Elsevier BV. - 0039-6028 .- 1879-2758. ; 600:2, s. 395-402
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Tidskriftsartikel (refereegranskat)abstract
- Using the density functional theory formulated within the framework of the exact muffin-tin orbitals method, we present a systematic study of the top layer relaxation and surface stress of 4d transition metals. Our calculations predict layer contractions for most surfaces. We also find that the relaxations of the close packed surfaces decrease with increasing atomic number through the 4d series. We propose that the relaxation is mainly due to the reduction of the number of sp electrons in the surface layer relative to bulk. The surface stress is found to be very sensitive to the relaxation and, therefore, an accurate determination of the layer relaxation is necessary for obtaining reliable values for the surface stress. Comparing the top layer relaxations for the close packed surfaces, we see essential deviations between data derived in different ab initio calculations. At the same time, the overall trend for the present surface stress of 4d metals is in reasonable agreement with recent full-potential data.
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| 428. |
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| 429. |
- Karlsson, Charlie, 1945-, et al.
(författare)
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Introduction : Human Capital and Agglomeration
- 2012
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Ingår i: The Regional Economics Of Knowledge And Talent. - : Edward Elgar Publishing Ltd. - 9781848443280 - 9781781953549 ; , s. 1-24
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Bokkapitel (refereegranskat)
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| 430. |
- 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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