| 1. |
- Andersson, Martin O., et al.
(författare)
-
Molecular detection of Babesia capreoli and Babesia venatorum in wild Swedish roe deer, Capreolus capreolus
- 2016
-
Ingår i: Parasites & Vectors. - : Springer Science and Business Media LLC. - 1756-3305. ; 9:1
-
Tidskriftsartikel (refereegranskat)abstract
- Background: The epidemiology of the zoonotic tick-transmitted parasite Babesia spp. and its occurrence in wild reservoir hosts in Sweden is unclear. In European deer, several parasite species, including Babesia capreoli and the zoonotic B. venatorum and B. divergens has been reported previously. The European roe deer, Capreolus capreolus, is an important and common part of the indigenous fauna in Europe, as well as an important host for Ixodes ricinus ticks, the vector of several Babesia spp. in Europe. Here, we aimed to investigate the occurrence of Babesia spp. in roe deer in Sweden. Findings: Roe deer (n = 77) were caught and sampled for blood. Babesia spp. was detected with a PCR assay targeting the 18S rRNA gene. The prevalence of Babesia spp. was 52 %, and two species were detected; B. capreoli and B. venatorum in 44 and 7.8 % of the individuals, respectively. Infection occurred both in summer and winter. Conclusions: We showed that roe deer in Sweden, close to the edge of their northern inland distributional range, are infected with Babesia spp. The occurrence of B. venatorum in roe deer imply that it is established in Sweden and the zoonotic implication of this finding should be regarded to a greater extent in future.
|
|
| 2. |
- Cardias, R., et al.
(författare)
-
The Bethe-Slater curve revisited; new insights from electronic structure theory
- 2017
-
Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- The Bethe-Slater (BS) curve describes the relation between the exchange coupling and interatomic distance. Based on a simple argument of orbital overlaps, it successfully predicts the transition from antiferromagnetism to ferromagnetism, when traversing the 3d series. In a previous article [Phys. Rev. Lett. 116, 217202 (2016)] we reported that the dominant nearestneighbour (NN) interaction for 3d metals in the bcc structure indeed follows the BS curve, but the trends through the series showed a richer underlying physics than was initially assumed. The orbital decomposition of the inter-site exchange couplings revealed that various orbitals contribute to the exchange interactions in a highly non-trivial and sometimes competitive way. In this communication we perform a deeper analysis by comparing 3d metals in the bcc and fcc structures. We find that there is no coupling between the E-g orbitals of one atom and T-2g orbitals of its NNs, for both cubic phases. We demonstrate that these couplings are forbidden by symmetry and formulate a general rule allowing to predict when a similar situation is going to happen. In gamma-Fe, as in alpha-Fe, we find a strong competition in the symmetry-resolved orbital contributions and analyse the differences between the high-spin and low-spin solutions.
|
|
| 3. |
- Daunfeldt, S-O, et al.
(författare)
-
Habit Formation in Food Consumption
- 2011
-
Ingår i: Oxford Handbook on the Economics of Food Consumption and Policy. ; , s. 770-790
-
Bokkapitel (övrigt vetenskapligt/konstnärligt)
|
|
| 4. |
|
|
| 5. |
- Keshavarz, Samara, et al.
(författare)
-
Exchange interactions of CaMnO3 in the bulk and at the surface
- 2017
-
Ingår i: Physical Review B Condensed Matter. - 0163-1829 .- 1095-3795. ; 95
-
Tidskriftsartikel (refereegranskat)abstract
- We present electronic and magnetic properties of CaMnO3 (CMO) as obtained from ab initio calculations. We identify the preferable magnetic order by means of density functional theory plus Hubbard U calculations and extract the effective exchange parameters (Jij ' s) using the magnetic force theorem. We find that the effects of geometrical relaxation at the surface as well as the change of crystal field are very strong and are able to influence the lower-energymagnetic configuration. In particular, our analysis reveals that the exchange interaction between the Mn atoms belonging to the surface and the subsurface layers is very sensitive to the structural changes. An earlier study [A. Filippetti and W. E. Pickett, Phys. Rev. Lett. 83, 4184 (1999)] suggested that this coupling is ferromagnetic and gives rise to the spin-flip (SF) process on the surface of CMO. In our work, we confirm their finding for an unrelaxed geometry, but once the structural relaxations are taken into account, this exchange coupling changes its sign. Thus, we suggest that the surface of CMO should have the same G-type antiferromagnetic order as in the bulk. Finally, we show that the suggested SF can be induced in the system by introducing an excess of electrons.
|
|
| 6. |
- Kvashnin, Yaroslav O., et al.
(författare)
-
Microscopic Origin of Heisenberg and Non-Heisenberg Exchange Interactions in Ferromagnetic bcc Fe
- 2016
-
Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 116:21
-
Tidskriftsartikel (refereegranskat)abstract
- By means of first principles calculations, we investigate the nature of exchange coupling in ferromagnetic bcc Fe on a microscopic level. Analyzing the basic electronic structure reveals a drastic difference between the 3d orbitals of E-g and T-2g symmetries. The latter ones define the shape of the Fermi surface, while the former ones form weakly interacting impurity levels. We demonstrate that, as a result of this, in Fe the T-2g orbitals participate in exchange interactions, which are only weakly dependent on the configuration of the spin moments and thus can be classified as Heisenberg-like. These couplings are shown to be driven by Fermi surface nesting. In contrast, for the E-g states, the Heisenberg picture breaks down since the corresponding contribution to the exchange interactions is shown to strongly depend on the reference state they are extracted from. Our analysis of the nearest-neighbor coupling indicates that the interactions among E-g states are mainly proportional to the corresponding hopping integral and thus can be attributed to be of double-exchange origin. By making a comparison to other magnetic transition metals, we put the results of bcc Fe into context and argue that iron has a unique behavior when it comes to magnetic exchange interactions.
|
|
| 7. |
- Lejaeghere, Kurt, et al.
(författare)
-
Reproducibility in density functional theory calculations of solids.
- 2016
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 351:6280, s. 1415-1422
-
Tidskriftsartikel (refereegranskat)abstract
- The widespread popularity of density functional theory has given rise to an extensive range of dedicated codes for predicting molecular and crystalline properties. However, each code implements the formalism in a different way, raising questions about the reproducibility of such predictions. We report the results of a community-wide effort that compared 15 solid-state codes, using 40 different potentials or basis set types, to assess the quality of the Perdew-Burke-Ernzerhof equations of state for 71 elemental crystals. We conclude that predictions from recent codes and pseudopotentials agree very well, with pairwise differences that are comparable to those between different high-precision experiments. Older methods, however, have less precise agreement. Our benchmark provides a framework for users and developers to document the precision of new applications and methodological improvements.
|
|
| 8. |
- O´Reilly, Ossian, et al.
(författare)
-
Coupled High-Order Finite Difference and Unstructured Finite Volume Methods for Earthquake Rupture Dynamics in Complex Geometries
- 2011
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Unstructured grid methods are well suited for earthquake problems in complex geometries, such as non-planar and branching faults. Unfortunately they are indefficient in comparsion wiht high-order finite differences. With the use of summation-by-parts (SBP) operators and the SAT penalty method (simultaneous approximation term) it is possible to couple unstructured finite volume methods with high-order finite difference methods in an accurate and stable way. The couple method is more efficient than the unstructured method alone. Another advantage of the SBP and SAT method is that it is possible to prove strict stability, meaning that the semi-discrete solution dissipates energy at a slightly faster rate than the continuous solution so that the error remains bounded in time, which is particulary useful for long time computations.
|
|
| 9. |
- O´Reilly, Ossian, et al.
(författare)
-
Earthquake Rupture dynamics in complex geometries using coupled high-order finite difference methods and finite volume methods
- 2012
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a 2-D multi-block method for earthquake rupture dynamics in complex geometries using summation-byparts (SBP) high-order finite differences on structured grids coupled to nite volume methods on unstructured meshes. The node-centered nite volume method is used on unstructured triangular meshes to resolve earthquake ruptures propagating along non-planar faults with complex geometrical features. The unstructured meshes discretize the fault geometry only in the vicinity of the faults and have collocated nodes on the fault boundaries. Away from faults, where no complex geometry is present, the seismic waves emanating from the earthquake rupture are resolved using the high-order finite difference method on coarsened structured grids, improving the computational efficiency while maintaining the accuracy of the method.In order for the SBP high-order nite difference method to communicate with the node-centered finite volume method in a stable manner, interface conditions are imposed using the simultaneous approximation term (SAT) penalty method. In the SAT method the interface conditions and boundary conditions are imposed in a weak manner.Fault interface conditions (rate-and-state friction) are also imposed in a provably stable manner using the SAT method. Another advantage of the SAT method is the ability to impose multiple boundary conditions at a single boundary node, e.g. at the triple junction of a branching fault.The accuracy and stability of the numerical implementation are veried using the method of manufactured solutions and against other numerical implementations. To demonstrate the potential of the method, we simulate an earthquake rupture propagating in a nonplanar fault geometry resolved with unstructured meshes in the fault zone and structured grids in the far-eld.
|
|
| 10. |
- O´Reilly, Ossian, et al.
(författare)
-
Earthquake Rupture Dynamics in Complex Geometries using Coupled Summation-By-Parts High-order Finite Difference Methods and Node-Centered Finite Volume Methods
- 2012
-
Ingår i: Souther California Earthquacke Center, Annual Meeting.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a 2-D multi-block method for earthquake rupture dynamics in complex geometries using summation-byparts (SBP) high-order nite di-erences on structured grids coupled to nite volume methods on unstructured meshes. The node-centered nite volume method is used on unstructured triangular meshes to resolve earthquake ruptures propagating along nonplanar faults with complex geometrical features. The unstructured meshes discretize the fault geometry only in the vicinity of the faults and have collocated nodes on the fault boundaries. Away from faults, where no complex geometry is present, the seismic waves emanating from the earthquake rupture are resolved using the high-order nite di-erence method on coarsened structured grids, improving the computational e ciency while maintaining the accuracy of the method.In order for the SBP high-order nite di-erence method to communicate with the node-centered nite volume method in a stable manner, interface conditions are imposed using the simultaneous approximation term (SAT) penalty method. In the SAT method the interface conditions and boundary conditions are imposed in a weak manner.Fault interface conditions (rate-and-state friction) are also imposed in a provably stable manner using the SAT method. Another advantage of the SAT method is the ability to impose multiple boundary conditions at a single boundary node, e.g., at the triple junction of a branching fault.The accuracy and stability of the numerical implementation are veried using the method of manufactured solutions and against other numerical implementations. To demonstrate the potential of the method, we simulate an earthquake rupture propagating in a nonplanar fault geometry resolved with unstructured meshes in the fault zone and structured grids in the far-eld.
|
|
