| 1. |
- Hansson, Jörgen, et al.
(författare)
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Clearance of Flight Control Laws for Time-Varying Parameters
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In this article exponential stability of the closed loop for the Saab AB VEGAS model controlled by a gain-scheduled linear fractional transformation controller is investigated for time-varying Mach-number. The analysis is based on parameter-dependent Lyapunov-functions which are obtained by investigating feasibility of linear matrix inequalities.
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| 2. |
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| 3. |
- Löfgren, N., et al.
(författare)
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Remote sessions and frequency analysis for improved insight into cerebral function during pediatric and neonatal intensive care.
- 2003
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Ingår i: IEEE transactions on information technology in biomedicine. - 1089-7771 .- 1558-0032. ; 7:4, s. 283-90
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Tidskriftsartikel (refereegranskat)abstract
- A project involving recording and analysing EEG together with cardiovascular signals and temperature has been initiated. The aim of this project is to establish difficulties and possibilities involved with implementing a system for remote sessions and analysing EEG in correlation with other physiological signals. One objective is to find indicators of cerebral function during postasphyxia neonatal intensive care and pediatric cardiopulmonary bypass surgery with hypothermia. Remote sessions for joint interpretation have been carried out between pediatricians and clinical neurophysiologists, and EEG has been analyzed using frequency analyzing tools. One result is the discovery of reversible spectral changes coinciding with blood pressure falls, which may indicate loss of autoregulation function. This finding is one outcome from initial use of a system, developed during the project to facilitate communication about, and analysis of the recorded signals. Thus, already from a limited number of remote sessions and the use of basic signal processing techniques, important results have been achieved and better insight has been gained of how cerebral function is affected by cardiopulmonary bypass surgery. In this paper, we present our experiences from introducing a system for remote consultations, and evaluate the use for such a system in the current applications.
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| 4. |
- Blennow, Kaj, 1958, et al.
(författare)
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No association between the alpha2-macroglobulin (A2M) deletion and Alzheimer's disease, and no change in A2M mRNA, protein, or protein expression.
- 2000
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Ingår i: Journal of neural transmission (Vienna, Austria : 1996). - : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 107:8-9, s. 1065-79
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Tidskriftsartikel (refereegranskat)abstract
- A polymorphism consisting of a deletion near the 5' splice site of exon 18 on the alpha2-macroglobulin (A2M) gene (A2M-2) has been suggested to be associated with Alzheimer's disease (AD) in family-based studies. We studied the A2M-2 allele together with the ApoE alleles in a large series on patients with AD (n = 449) and age-matched controls (n = 349). Neuropathologically confirmed diagnoses were available in 199 cases (94 AD and 107 control cases). We found no increase in A2M-2 genotype or allele frequencies in AD (27.5% and 14.6%) versus controls (26.4% and 14.9%). In contrast, a marked increase (p < 0.0001) in ApoE epsilon4 genotype or allele frequencies was found in AD (66.6% and 41.2%) as compared with controls (29.8% and 16.5%), suggesting sufficient statistical power in our sample. No relation was found between the A2M-2 and the ApoE epsilon4 allele. No change in A2M exon 17-18 mRNA size or sequence or A2M protein size was found in cases carrying the A2M-2 deletion, suggesting that there is no biological consequences of the A2M intronic deletion. No change in A2M protein level in cerebrospinal fluid was found in AD, suggesting that the A2M-2 allele does not effect the A2M protein expression in the brain. The lack of an association between the A2M-2 allele and AD in the present study, and the lack of abnormalities in the A2M mRNA or protein suggest that the A2M-2 allele is not associated with AD.
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| 5. |
- Eriksson, Per, et al.
(författare)
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A comparison on the developmental neurotoxic effects of hexabromocyclododecane, 2,2´,4,4´,5,5´-hexabromodiphenylether (PBDE 153) and 2,2´,4,4´,5,5´-hexachlorobiphenylether (PCB 153).
- 2002
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Ingår i: Organohalogen Compounds. ; 57, s. 389-390
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Tidskriftsartikel (refereegranskat)
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| 6. |
- Favrin, Giorgio, et al.
(författare)
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Folding of a small helical protein using hydrogen bonds and hydrophobicity forces.
- 2002
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Ingår i: Proteins. - : Wiley. - 0887-3585. ; 47:2, s. 99-105
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Tidskriftsartikel (refereegranskat)abstract
- A reduced protein model with five to six atoms per amino acid and five amino acid types is developed and tested on a three-helix-bundle protein, a 46-amino acid fragment from staphylococcal protein A. The model does not rely on the widely used Go approximation, which ignores non-native interactions. We find that the collapse transition is considerably more abrupt for the protein A sequence than for random sequences with the same composition. The chain collapse is found to be at least as fast as helix formation. Energy minimization restricted to the thermodynamically favored topology gives a structure that has a root-mean-square deviation of 1.8 A from the native structure. The sequence-dependent part of our potential is pairwise additive. Our calculations suggest that fine-tuning this potential by parameter optimization is of limited use.
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| 7. |
- Favrin, Giorgio, et al.
(författare)
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Sequence-based study of two related proteins with different folding behaviors
- 2004
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Ingår i: Proteins. - : Wiley. - 0887-3585. ; 54:1, s. 8-12
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Tidskriftsartikel (refereegranskat)abstract
- Z(SPA-1) is an engineered protein that binds to its parent, the three-helix-bundle Z domain of staphylococcal protein A. Uncomplexed Z(SPA-1) shows a reduced helix content and a melting behavior that is less cooperative, compared with the wild-type Z domain. Here we show that the difference in folding behavior between these two sequences can be partly understood in terms of an off-lattice model with 5-6 atoms per amino acid and a minimalistic potential, in which folding is driven by backbone hydrogen bonding and effective hydrophobic attraction. (C) 2003 Wiley-Liss, Inc.
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| 8. |
- Favrin, Giorgio, et al.
(författare)
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Two-state folding over a weak free-energy barrier
- 2003
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Ingår i: Biophysical Journal. - 1542-0086. ; 85:3, s. 1457-1465
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Tidskriftsartikel (refereegranskat)abstract
- We present a Monte Carlo study of a model protein with 54 amino acids that folds directly to its native three-helix-bundle state without forming any well-defined intermediate state. The free-energy barrier separating the native and unfolded states of this protein is found to be weak, even at the folding temperature. Nevertheless, we find that melting curves to a good approximation can be described in terms of a simple two-state system, and that the relaxation behavior is close to single exponential. The motion along individual reaction coordinates is roughly diffusive on timescales beyond the reconfiguration time for a single helix. A simple estimate based on diffusion in a square-well potential predicts the relaxation time within a factor of two.
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| 9. |
- Hansson, Anders, et al.
(författare)
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Comparison of Two Structure-Exploiting Optimization Algorithms for Integral Quadratic Constraints
- 2003
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Ingår i: Proceedings of the 4th IFAC symposium on Robust Control Design. - Linköping : Linköping University Electronic Press. - 9780080440125
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Konferensbidrag (refereegranskat)abstract
- As the semidefinite programs that result from integral quadratic contstraints are usually large it is important to implement efficient algorithms. The interior-point algorithms in this paper are primal-dual potential reduction methods and handle multiple constraints. Two approaches are made. For the first approach the computational cost is dominated by a least-squares problem that has to be solved in each iteration. The least squares problem is solved using an iterative method, namely the conjugate gradient method. The computational effort for the second approach is dominated by forming a linear system of equations. This systems of equations is used to compute the search direction in each iteration. If the number of variables are reduced by solving a smaller subproblem the resulting system has a very nice structure and can be solved efficiently. The first approach is more efficient for larger problems but is not as numerically stable.
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| 10. |
- Hansson, Anders, et al.
(författare)
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Efficient Implementations of Interior-Point Methods for Integral Quadratic Constraints
- 2001
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Ingår i: Proceedings of the Fourth SIAM Conference on Linear Algebra in Signals, Systems and Control.
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Konferensbidrag (refereegranskat)abstract
- We describe two strategies for exploiting structure in implementations of interior-point methods for the semidefinite programs (SDPs) that result from integral quadratic constraints. The first approach uses inexact search directions computed by the conjugate gradient algorithm. In the second approach we solve the problem via the dual. Simplifying the dual problem results in an SDP that has fewer variables (O(n)) than the primal SDP (O(n2) variables), and that can be solved efficiently using standard methods.
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