| 61. |
- Duwig, Christophe, et al.
(author)
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Study of flame stabilization in a swirling combustor using a new flamelet formulation
- 2005
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In: Combustion Science and Technology. - : Informa UK Limited. - 0010-2202 .- 1563-521X. ; 177:8, s. 1485-1510
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Journal article (peer-reviewed)abstract
- The dynamics in a swirl-stabilized flame is studied using large eddy simulation (LES). We account for the effect of turbulence on the flame through a model based on a filtered flamelet technique. The model provides a consistent and robust reaction-diffusion expression for simulating the correct propagation of premixed flames. The filtered flamelet formulation has been implemented into a high-order-accurate LES code and used to study the flame stabilization and the combustion dynamics in a gas-turbine combustion chamber. The effects of inlet boundary conditions, in terms of velocity and equivalence ratio radial profiles, have been studied. The flow is found to be very sensitive to small changes in terms of flame shapes and anchoring position. The sensitivity of the results to the subgrid-scale flame thickness has also been investigated. The influence on the flame position is not significant. However, a too-large subgridscale flame thickness leads to different flame dynamics.
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| 62. |
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| 63. |
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| 64. |
- Ekholm, Tomas, et al.
(author)
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A Hardy inequality in twisted waveguides
- 2008
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In: Archive for Rational Mechanics and Analysis. - : Springer Science and Business Media LLC. - 0003-9527 .- 1432-0673. ; 188:2, s. 245-264
-
Journal article (peer-reviewed)abstract
- We show that twisting of an infinite straight three-dimensional tube with non-circular cross-section gives rise to a Hardy-type inequality for the associated Dirichlet Laplacian. As an application we prove certain stability of the spectrum of the Dirichlet Laplacian in locally and mildly bent tubes. Namely, it is known that any local bending, no matter how small, generates eigenvalues below the essential spectrum of the Laplacian in the tubes with arbitrary cross-sections rotated along a reference curve in an appropriate way. In the present paper we show that for any other rotation some critical strength of the bending is needed in order to induce a non-empty discrete spectrum.
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| 65. |
- Ekholm, Tomas, et al.
(author)
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Lieb-Thirring inequalities on the half-line with critical exponent
- 2008
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In: Journal of the European Mathematical Society (Print). - 1435-9855 .- 1435-9863. ; 10:3, s. 739-755
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Journal article (peer-reviewed)abstract
- We consider the operator -d(2)/dr(2) - V in L-2(R+) with Dirichlet boundary condition at the origin. For the moments of its negative eigenvalues we prove the bound for any alpha is an element of [0, 1) and gamma >= (1 - alpha)/2. This includes a Lieb-Thirring inequality in the critical endpoint case.
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| 66. |
- Ekholm, Tomas, et al.
(author)
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Remarks about Hardy inequalities on metric trees
- 2008
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In: Analysis on Graphs and Its Applications. - 0082-0717. - 9780821844717 ; 77, s. 369-379
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Conference paper (peer-reviewed)abstract
- We find sharp conditions on the growth of a rooted regular metric tree Such that the Neumann Laplacian on the tree satisfies a Hardy inequality. In particular, we consider homogeneous metric trees. Moreover, we show that a non-trivial Aharonov-Bohm magnetic field leads to a Hardy inequality on a loop graph.
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| 67. |
- Ekman, Marianne, et al.
(author)
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Developmental magic? Two takes on a dialogue conference
- 2007
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In: Journal of Organizational Change Management. - : Emerald. - 0953-4814 .- 1758-7816. ; 20:1, s. 8-25
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Journal article (peer-reviewed)abstract
- Purpose - This paper draws on the metaphor of magic to explore the role of dialogue conferences and subsequent activities as a tool for organizational development and change. The metaphor is introduced and elaborated as a means of allowing critical reflection on action research projects. Design/methodology/approach - In the empirical setting of a change project in a regional health authority in Sweden, researchers designed and facilitated a development coalition for introducing integrated care. This required an action research intervention that supported the establishment of new relationships and developmental practices across both organizational and professional boundaries. Findings - The unfolding of developmental processes set in train by dialogue conferences are shown as being a dynamic process of magic underpinned by the principles of democratic dialogue. Originality/value - By drawing attention to the three keywords of development, participation and dialogue three sites have been identified for critical reflection and reflexivity in action research. Magic is argued as an activity wherein the seemingly impossible is made to happen in these areas; equally it can be an activity of simple illusion whereby appearance is at odds with reality.
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| 68. |
- Ellert, Mattias, et al.
(author)
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Advanced Resource Connector middleware for lightweight computational Grids
- 2007
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In: Future generations computer systems. - : Elsevier BV. - 0167-739X .- 1872-7115. ; 23:2, s. 219-240
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Journal article (peer-reviewed)abstract
- As computational Grids move away from the prototyping state, reliability, performance and ease of use and maintenance become focus areas of their adoption. In this paper, we describe ARC (Advanced Resource Connector) Grid middleware, where these issues have been given special consideration. We present an in-depth view of the existing components of ARC, and discuss some of the new components, functionalities and enhancements currently under development. This paper also describes architectural and technical choices that have been made to ensure scalability, stability and high performance. The core components of ARC have already been thoroughly tested in demanding production environments, where it has been in use since 2002. The main goal of this paper is to provide a first comprehensive description of ARC.
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| 69. |
- Elmlund, Hans, et al.
(author)
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A new cryo-EM single-particle Ab initio reconstruction method visualizes secondary structure elements in an ATP-Fueled AAA+ motor
- 2008
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In: Journal of Molecular Biology. - : Elsevier BV. - 1089-8638 .- 0022-2836. ; 375:4, s. 934-947
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Journal article (peer-reviewed)abstract
- The generation of ab initio three-dimensional (3D) models is a bottleneck in the studies of large macromolecular assemblies by single-particle cryo-electron microscopy. We describe here a novel method, in which established methods for two-dimensional image processing are combined with newly developed programs for joint rotational 3D alignment of a large number of class averages (RAD) and calculation of 3D volumes from aligned projections (VolRec). We demonstrate the power of the method by reconstructing an 660-kDa ATP-fueled AAA+ motor to 7.5 Å resolution, with secondary structure elements identified throughout the structure. We propose the method as a generally applicable automated strategy to obtain 3D reconstructions from unstained single particles imaged in vitreous ice.
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| 70. |
- Elmlund, Hans, et al.
(author)
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Cryo-EM Reveals Promoter DNA Binding and Conformational Flexibility of the General Transcription Factor TFIID
- 2009
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In: Structure. - : Elsevier BV. - 0969-2126 .- 1878-4186. ; 17:11, s. 1442-1452
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Journal article (peer-reviewed)abstract
- The general transcription factor IID (TFIID) is required for initiation of RNA polymerase II-dependent transcription at many eukaryotic promoters. TFIID comprises the TATA-binding protein (TBP) and several conserved TBP-associated factors (TAFs). Recognition of the core promoter by TFIID assists assembly of the preinitiation complex. Using cryo-electron microscopy in combination with methods for ab initio single-particle reconstruction and heterogeneity analysis, we have produced density maps of two conformational states of Schizosaccharomyces pombe TFIID, containing and lacking TBP. We report that TBP-binding is coupled to a massive histone-fold domain rearrangement. Moreover, docking of the TBP-TAF1(N-terminus) atomic structure to the THID map and reconstruction of a TAF-promoter DNA complex helps to account for TAF-dependent regulation of promoter-TBP and promoter-TAF interactions.
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