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| 2. |
- Lenhof, Bernd, 1975, et al.
(författare)
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A comparison of variational formats for porous media subjected to dynamic loading
- 2011
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Ingår i: International Journal for Numerical and Analytical Methods in Geomechanics. - : Wiley. - 0363-9061 .- 1096-9853. ; 35:7, s. 807-823
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a comparison of two variational formats for fully saturated porous media subjected to dynamic loading, whereby the general situation of relative fluid acceleration is considered: (1) the classical three-field (u, p, w)-format and (2) a novel two-field (u, p)-format, where the seepage velocity w is a spatially 'local' field whose treatment resembles that of internal variables in material models. The limited numerical comparison shows that the (u, p)-format competes well with the (u, p, w)-format. Indeed, it is consistent with the general acceleration modeling in the full range of permeabilities. Moreover, in the low permeability regime (where the magnitude of w is insignificant), the new format reflects the situation pertinent to 'added-mass' and is more efficient than the classical (u, p, w)-format. Finally, the (u, p)-format can conveniently be implemented in existing FE-codes based on the 'added mass' formulation.
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| 3. |
- Magnusson, Patrik K. E., et al.
(författare)
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The Swedish Twin Registry : establishment of a biobank and other recent developments
- 2013
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Ingår i: Twin Research and Human Genetics. - Cambridge, United Kingdom : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 16:1, s. 317-329
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Tidskriftsartikel (refereegranskat)abstract
- The Swedish Twin Registry (STR) today contains more than 194,000 twins and more than 75,000 pairs have zygosity determined by an intra-pair similarity algorithm, DNA, or by being of opposite sex. Of these, approximately 20,000, 25,000, and 30,000 pairs are monozygotic, same-sex dizygotic, and opposite-sex dizygotic pairs, respectively. Since its establishment in the late 1950s, the STR has been an important epidemiological resource for the study of genetic and environmental influences on a multitude of traits, behaviors, and diseases. Following large investments in the collection of biological specimens in the past 10 years we have now established a Swedish twin biobank with DNA from 45,000 twins and blood serum from 15,000 twins, which effectively has also transformed the registry into a powerful resource for molecular studies. We here describe the main projects within which the new collections of both biological samples as well as phenotypic measures have been collected. Coverage by year of birth, zygosity determination, ethnic heterogeneity, and influences of in vitro fertilization are also described.
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| 4. |
- Pandey, Gaurav Kumar, et al.
(författare)
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The risk-associated long noncoding RNA NBAT-1 controls neuroblastoma progression by regulating cell proliferation and neuronal differentiation.
- 2014
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Ingår i: Cancer Cell. - : Elsevier BV. - 1535-6108 .- 1878-3686. ; 26:5, s. 722-737
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Tidskriftsartikel (refereegranskat)abstract
- Neuroblastoma is an embryonal tumor of the sympathetic nervous system and the most common extracranial tumor of childhood. By sequencing transcriptomes of low- and high-risk neuroblastomas, we detected differentially expressed annotated and nonannotated long noncoding RNAs (lncRNAs). We identified a lncRNA neuroblastoma associated transcript-1 (NBAT-1) as a biomarker significantly predicting clinical outcome of neuroblastoma. CpG methylation and a high-risk neuroblastoma associated SNP on chromosome 6p22 functionally contribute to NBAT-1 differential expression. Loss of NBAT-1 increases cellular proliferation and invasion. It controls these processes via epigenetic silencing of target genes. NBAT-1 loss affects neuronal differentiation through activation of the neuronal-specific transcription factor NRSF/REST. Thus, loss of NBAT-1 contributes to aggressive neuroblastoma by increasing proliferation and impairing differentiation of neuronal precursors.
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| 5. |
- Brouzoulis, Jim, 1984, et al.
(författare)
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Strategies for planar crack propagation based on the concept of material forces
- 2011
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Ingår i: Computational Mechanics. - : Springer Science and Business Media LLC. - 1432-0924 .- 0178-7675. ; 47:3, s. 295-304
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a computational framework for the simulation of planar crack growth (including kinking) driven by "material forces". An evolution law for the crack tip position is formulated, which is shown to give rise to different propagation strategies when subjected to certain assumptions on regularity. Three such strategies, that previously have been proposed in the literature in principle: Explicit Proportional Extension (EPE), Implicit Proportional Extension (IPE) and Maximum Parallel Release Rate (MPRR), are outlined and assessed. Based on the results of two numerical examples, it is concluded that the presented propagation strategies produce almost identical results and are robust with respect to time discretization.
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| 6. |
- Draganis, Andreas, 1984, et al.
(författare)
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An Arbitrary Lagrangian Eulerian Formulation For Simulation Of Wheel-Rail Contact
- 2010
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Ingår i: Proceedings of NSCM-23: the 23rd Nordic Seminar on Computational Mechanics, Anders Eriksson, Gunnar Tibert, 21-22 Oktober, 2010, KTH, Stockholm. - 0348-467X. ; 2010, s. 173-176
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Konferensbidrag (refereegranskat)abstract
- A novel ALE-formulation of a rolling wheel is presented in the context of finite element simulations. Numerical examples illustrate the proposed strategy for a two-dimensionalproblem.
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| 7. |
- Draganis, Andreas, 1984, et al.
(författare)
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Finite element analysis of transient thermomechanical rolling contact using an efficient arbitrary Lagrangian-Eulerian description
- 2014
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Ingår i: Computational Mechanics. - : Springer Science and Business Media LLC. - 1432-0924 .- 0178-7675. ; 54:2, s. 389-405
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical and computational framework for the analysis of thermomechanically coupled transient rolling contact, based on an arbitrary Lagrangian-Eulerian (ALE) kinematical description, is developed. A finite element formulation featuring 2D cylinder-plate rolling contact is implemented. The implementation features penalty-type contact formulations for mechanical and thermal contact. It is noted that the ALE formulation allows for a simplified time description, a compact computational domain and localized mesh refinement. Numerical simulations considering stationary and transient rolling conditions are presented. Highlighted aspects include the influence of variations in thermal contact conductivity, rolling speed and external mechanical load on the contact interface heat flow. The model is shown to give predictions in qualitative agreement with results in the literature. For the velocity range studied, numerical issues such as spurious numerical dissipation/oscillations in the temperature field are noted to have a prominent influence. These phenomena are addressed using a Streamline-Upwind Petrov-Galerkin stabilization scheme together with a bubble function approach.
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| 8. |
- Draganis, Andreas, 1984, et al.
(författare)
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Modelling the thermomechanical wheel–rail interface during rolling contact
- 2012
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Ingår i: Proceedings of the 9th International Conference on Contact Mechanics and Wear of Rail/Wheel Systems (CM2012).
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Konferensbidrag (refereegranskat)abstract
- A theoretical and computational framework for the analysis of thermomechanically coupled transient rolling contact based on an arbitrary Lagrangian–Eulerian (ALE) kinematical description is developed. A finite element formulation featuring 2D cylinder–plate rolling contact is implemented. The implementation features penalty- type contact formulations for normal/tangential mechanical and thermal contact. It is noted that the ALE formulation allows for a simplified time description, a compact computational domain and localized mesh refinement. Numerical simulations considering stationary rolling conditions featuring full slip are presented.
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| 9. |
- Draganis, Andreas, 1984, et al.
(författare)
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Numerical evaluation of the transient response due to non-smooth rolling contact using an arbitrary Lagrangian–Eulerian formulation
- 2012
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Ingår i: Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology. - : SAGE Publications. - 1350-6501 .- 2041-305X. ; 226:J1, s. 36-45
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical and numerical framework to evaluate rolling contact using an arbitrary Lagrangian–Eulerian (ALE) formulation is established. A finite element formulation is imple- mented featuring cylinder–plate contact, automated mesh refinement, non-reflecting boundary conditions, and the ability to incorporate surface roughness through user-defined gap functions. Presented examples include rolling contact on a corrugated surface and negotiation of a surface discontinuity. Sensitivity and validation analyses are presented and show the model to be robust and the trends in parametric responses to be reasonable as compared to results in literature. Owing to the ALE formulation, the model can be kept very compact and the computational demands very modest.
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| 10. |
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