| 11. |
- Sendeski, Mauricio, et al.
(författare)
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Iodixanol, Constriction of Medullary Descending Vasa Recta, and Risk for Contrast Medium-induced Nephropathy
- 2009
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Ingår i: Radiology. - : Radiological Society of North America (RSNA). - 0033-8419 .- 1527-1315. ; 251:3, s. 697-704
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To determine whether a type of contrast medium (CM), iodixanol, modifies outer medullary descending vasa recta (DVR) vasoreactivity and nitric oxide (NO) production in isolated microperfused DVR. Materials and Methods: Animal handling conformed to the Animal Care Committee Guidelines of all participating institutions. Single specimens of DVR were isolated from rats and perfused with a buffered solution containing iodixanol. A concentration of 23 mg of iodine per milliliter was chosen to mimic that expected to be used in usual examinations in humans. Luminal diameter was determined by using video microscopy, and NO was measured by using fluorescent techniques. Results: Iodixanol led to 52% reduction of DVR luminal diameter, a narrowing that might interfere with passage of erythrocytes in vivo. Vasoconstriction induced by angiotensin II was enhanced by iodixanol. Moreover, iodixanol decreased NO bioavailability by more than 82%. Use of 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl (a superoxide dismutase mimetic) prevented both vasoconstriction with iodixanol alone and increased constriction with angiotensin II caused by CM. Conclusion: Iodixanol in doses typically used for coronary interventions constricts DVR, intensifies angiotensin II-induced constriction, and reduces bioavailability of NO. CM-induced nephropathy may be related to these events and scavenging of reactive oxygen species might exert a therapeutic benefit by preventing the adverse effects that a CM has on medullary perfusion.
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| 12. |
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| 13. |
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| 14. |
- Almqvist, Andreas, et al.
(författare)
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Homogenization of the unstationary incompressible Reynolds equation
- 2007
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Ingår i: Tribology International. - : Elsevier BV. - 0301-679X .- 1879-2464. ; 40:9, s. 1344-1350
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Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to the effects of surface roughness during hydrodynamic lubrication. In the numerical analysis a very fine mesh is needed to resolve the surface roughness, suggesting some type of averaging. A rigorous way to do this is to use the general theory of homogenization. In most works about the influence of surface roughness, it is assumed that only the stationary surface is rough. This means that the governing Reynolds type equation does not involve time. However, recently, homogenization was successfully applied to analyze a situation where both surfaces are rough and the lubricant is assumed to have constant bulk modulus. In this paper we will consider a case where both surfaces are assumed to be rough, but the lubricant is incompressible. It is also clearly demonstrated, in this case that homogenization is an efficient approach. Moreover, several numerical results are presented and compared with those corresponding to where a constant bulk modulus is assumed to govern the lubricant compressibility. In particular, the result shows a significant difference in the asymptotic behavior between the incompressible case and that with constant bulk modulus.
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| 15. |
- Bahar, Bahram, et al.
(författare)
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Developing A-GPS as a Student Project
- 2006
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Rapport (populärvet., debatt m.m.)abstract
- The project consists of ten fourth-year computer science students at Uppsala University developing an A-GPS (Assisted-GPS) system. During the fall term of 2005 the students have developed a module for GPS-calculations in a GSM-network and an application that demonstrates a possible way of using the calculations module. This paper describes the design, the development process and the results of the project.
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| 16. |
- Bredthauer, Andreas, et al.
(författare)
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First-order supersymmetric sigma models and target space geometry
- 2006
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Ingår i: Journal of High Energy Physics. ; 0601, s. 144-
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Tidskriftsartikel (refereegranskat)abstract
- We study the conditions under which N=(1,1) generalized sigma models support an extension to N=(2,2). The enhanced supersymmetry is related to the target space complex geometry. Concentrating on a simple situation, related to Poisson sigma models, we develop a language that may help us analyze more complicated models in the future. In particular, we uncover a geometrical framework which contains generalized complex geometry as a special case.
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| 17. |
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| 18. |
- Bredthauer, Andreas, et al.
(författare)
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Generalized Kähler geometry from supersymmetric sigma models
- 2006
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Ingår i: Letters in Mathematical Physics. - : Springer Science and Business Media LLC. - 0377-9017 .- 1573-0530. ; 77:3, s. 291-308
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Tidskriftsartikel (refereegranskat)abstract
- We give a physical derivation of generalized Kahler geometry. Starting from a supersymmetric nonlinear sigma model, we rederive and explain the results of Gualtieri (Generalized complex geometry, DPhil thesis, Oxford University, 2004) regarding the equivalence between generalized Kahler geometry and the bi-hermitean geometry of Gates et al. (Nucl Phys B248:157, 1984). When cast in the language of supersymmetric sigma models, this relation maps precisely to that between the Lagrangian and the Hamiltonian formalisms. We also discuss topological twist in this context.
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| 19. |
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| 20. |
- Carlsson, Bengt, et al.
(författare)
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Security Aspects on Inter-Organizational Cooperation Using Wrapper Agents
- 2005
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Konferensbidrag (refereegranskat)abstract
- The significance of electronic information exchange in interorganizational cooperation is well-known. We will here focus on the particular requirements of SMEs. We describe a general “wrapper agent” solution based on open source freeware that makes it possible (in principle) for any business system to exchange information with any other business system. It has been successfully applied in a pilot study involving two companies in a transport chain using different business systems. We also suggest further improvements by addressing security and privacy issues as well as an extended, possibly dynamic, set of involved companies and higher levels of cooperation.
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