| 2611. |
- Hansen, H. A., et al.
(författare)
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Reachability analysis of complex planar hybrid systems
- 2013
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Ingår i: Science of Computer Programming. - : Elsevier BV. - 0167-6423. ; 78:12, s. 2511-2536
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid systems are systems that exhibit both discrete and continuous behavior. Reachability, the question of whether a system in one state can reach some other state, is undecidable for hybrid systems in general. In this paper we are concerned with GSPDIs, 2-dimensional systems generalizing SPDIs (planar hybrid systems based on "simple polygonal differential inclusions"), for which reachability have been shown to be decidable. GSPDIs are useful to approximate 2-dimensional control systems, allowing the verification of safety properties of such systems. In this paper we present the following two contributions: (i) an optimized algorithm that answers reachability questions for GSPDIs, where all cycles in the reachability graph are accelerated. (ii) An algorithm by which more complex planar hybrid automata are over-approximated by GSPDIs subject to two measures of precision. We prove soundness, completeness, and termination of both algorithms, and discuss their implementation. (C) 2013 Elsevier B.V. All rights reserved.
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| 2612. |
- Hansen, T. F., et al.
(författare)
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Interpreting the Evolutionary Regression: The Interplay Between Observational and Biological Errors in Phylogenetic Comparative Studies
- 2012
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Ingår i: Systematic Biology. - Oxford : Oxford University Press (OUP). - 1063-5157 .- 1076-836X. ; 61:3, s. 413-425
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Tidskriftsartikel (refereegranskat)abstract
- Regressions of biological variables across species are rarely perfect. Usually, there are residual deviations from the estimated model relationship, and such deviations commonly show a pattern of phylogenetic correlations indicating that they have biological causes. We discuss the origins and effects of phylogenetically correlated biological variation in regression studies. In particular, we discuss the interplay of biological deviations with deviations due to observational or measurement errors, which are also important in comparative studies based on estimated species means. We show how bias in estimated evolutionary regressions can arise from several sources, including phylogenetic inertia and either observational or biological error in the predictor variables. We show how all these biases can be estimated and corrected for in the presence of phylogenetic correlations. We present general formulas for incorporating measurement error in linear models with correlated data. We also show how alternative regression models, such as major axis and reduced major axis regression, which are often recommended when there is error in predictor variables, are strongly biased when there is biological variation in any part of the model. We argue that such methods should never be used to estimate evolutionary or allometric regression slopes.
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| 2613. |
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| 2614. |
- Hanson, Ellen, et al.
(författare)
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Genetic Variants of Coagulation Factor XI Show Association with Ischemic Stroke Up to 70 Years of Age
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:9
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Tidskriftsartikel (refereegranskat)abstract
- Coagulation factor XI (FXI) has an important role in the propagation and stabilization of a thrombus upon vessel injury. High FXI levels have been implicated in thrombotic diseases including ischemic stroke. The aim of our study was to investigate whether FXI gene (F11) variants are associated with ischemic stroke. The discovery sample, the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), included 844 patients with ischemic stroke and 668 controls, all aged 18-70 years. Replication was performed in the Lund Stroke Register (LSR) and Malmö Diet and Cancer study (MDC), together including 1213 patients and 788 controls up to 70 years of age, and in total 3145 patients and 1793 controls (18-102 years). Seven F11 single-nucleotide polymorphisms (SNPs) were selected using a tagging approach. The SNPs rs3733403, rs925451, and rs1593 showed independent associations with overall ischemic stroke in SAHLSIS, ORs of 0.74 (95% CI 0.59-0.94), 1.24 (95% CI 1.06-1.46), and 0.70 (95% CI 0.55-0.90), respectively. The association for rs925451 was replicated in the LSR and MDC sample in a pre-specified analysis of subjects aged 70 years or younger, OR of 1.16 (95% CI 1.00-1.34), whereas no SNP was replicated when all ages were included. In line with this, one F11 haplotype was associated with overall ischemic stroke in the discovery sample and in the replication sample ≤70 years. We found significant associations between F11 variation and overall ischemic stroke up to 70 years of age. These findings motivate further studies on the role of F11 in ischemic stroke, especially in younger individuals.
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| 2615. |
- Hanson, Ellen, et al.
(författare)
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No evidence for an association between ABO blood group and overall ischemic stroke or any of the major etiologic subtypes
- 2012
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Ingår i: Thrombosis Research. - : Elsevier BV. - 0049-3848 .- 1879-2472. ; 130:3, s. 339-342
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The ABO blood group system is encoded by one gene, ABO. Previous studies have reported an association between blood group non-O (i.e. phenotype A, B or AB) and myocardial infarction. Studies on stroke and ABO are, however, more scarce. Therefore, we aimed to investigate whether ABO phenotype or genotype is associated with ischemic stroke and/or etiologic subtypes of ischemic stroke. Materials and methods: The study was performed in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which comprises 600 patients with ischemic stroke before the age of 70 years, and 600 matched controls. Patients were classified according to the TOAST criteria. Results: There was no significant association between ABO phenotype (blood group O vs. non-O) and overall ischemic stroke (multivariable odds ratio of 0.9, 95% confidence interval 0.7-1.2). This was also true for blood group O vs. A and O vs. B. Furthermore, no association between ABO genotypes and ischemic stroke was detected. The ischemic stroke subtype analysis was confined to large-vessel disease, small-vessel disease, cardioembolic stroke and cryptogenic stroke. In this analysis, there was no significant association between any ischemic stroke subtype and ABO phenotype or genotype. Conclusions: The findings in this study suggest that ABO phenotype or genotype does not have a major impact in the pathophysiology of ischemic stroke or any of the ischemic stroke subtypes.
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| 2616. |
- Hanson, Ellen, et al.
(författare)
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Plasma factor VII-activating protease antigen levels and activity are increased in ischemic stroke.
- 2012
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Ingår i: Journal of thrombosis and haemostasis : JTH. - : Elsevier BV. - 1538-7836 .- 1538-7933. ; 10:5, s. 848-56
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Tidskriftsartikel (refereegranskat)abstract
- Factor VII-activating protease (FSAP) is a recently discovered plasma protease with a role in the regulation of hemostasis and vascular remodeling processes. Higher levels and activity of FSAP have been reported in patients with deep vein thrombosis, but there are no data on plasma FSAP in ischemic stroke (IS).
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| 2617. |
- Hanson, Ellen, et al.
(författare)
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Plasma levels of von Willebrand factor in the etiologic subtypes of ischemic stroke
- 2011
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Ingår i: Journal of Thrombosis and Haemostasis. - : Elsevier BV. - 1538-7933 .- 1538-7836. ; 9:2, s. 275-281
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Tidskriftsartikel (refereegranskat)abstract
- Background: Compared with coronary artery disease, there are few studies on von Willebrand factor (VWF) in ischemic stroke (IS). Moreover, there is little information on VWF in the etiologic subtypes of IS. Objectives: The aim of the present study was to investigate VWF in IS and in the etiologic subtypes of IS. Patients/methods: The Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS) is a case-control study comprising 600 patients and 600 matched controls. Etiologic IS subtype was defined according to the TOAST criteria. Blood sampling was performed in the acute phase and after 3 months. Results: The levels of VWF were increased in overall IS, at both time-points. The 3-month VWF levels were increased in the subtypes of large-vessel disease (LVD), cardioembolic (CE) stroke and cryptogenic stroke, but not in the subtype of small-vessel disease (SVD), as compared with the controls. The acute phase VWF levels were significantly increased in all four subtypes. In the multivariate regression analysis, with vascular risk factors as covariates, the 3-month VWF levels were associated with CE stroke and cryptogenic stroke, and the acute phase VWF levels with all subtypes. There were significant subtype-specific differences in VWF, with the highest levels in LVD and CE stroke. Conclusions: The present results show that VWF levels are increased in patients with IS. Furthermore, the VWF levels differ between etiologic IS subtypes and thus, it is important to consider etiologic subtypes in future studies of VWF in patients with IS.
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| 2618. |
- Hanson, Maj, 1939, et al.
(författare)
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Arrays of elliptical Fe(001) nanoparticles: Magnetization reversal, dipolar interactions, and effects of finite array sizes
- 2015
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 2469-9950 .- 2469-9969 .- 1550-235X. ; 92:9
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Tidskriftsartikel (refereegranskat)abstract
- The magnetic properties of arrays of nanoparticles are determined by the interplay between the individual particle properties and the dipolar interactions between them. Here we present a study of arrays of elliptical Fe(001) particles of thickness 10–50 nm. The aspect ratios of the ellipses are 1:3, their short axes a=50, 100, or 150 nm, and the periodicity of the rectangular arrays is either two or four times the corresponding axes of the ellipses. Magnetic measurements together with numerical and micromagnetic calculations yield a consistent picture of the arrays, comprising single-domain nanoparticles. We show that the magnetization reversal, occurring in the range 100–400 mT for fields applied along the long axis, is mainly determined by the properties of the corresponding single Fe ellipses. The interaction fields of the order of tens of mT can be tuned by the array configurations. For the actual arrays the interactions promote switching. For film thicknesses below the Bloch wall width parameter of Fe, lw=22 nm, magnetization reversal occurs without formation of domain walls or vortices. Within this range arrays may be tuned to obtain a well-defined switching field. Two general conclusions are drawn from the calculations: the character of the interaction, whether it promotes or delays magnetization reversal, is determined by the aspect ratio of the array grid, and the interaction strength saturates as the size of the array increases.
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| 2619. |
- Hansson, A., et al.
(författare)
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The direction of human mesenchymal stem cells into the chondrogenic lineage is influenced by the features of hydrogel carriers
- 2017
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Ingår i: Tissue and Cell. - : Elsevier BV. - 1532-3072 .- 0040-8166. ; 49:1, s. 35-44
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Tidskriftsartikel (refereegranskat)abstract
- Low back pain is a major public health issue in the Western world, one main cause is believed to be intervertebral disc (IVD) degeneration. To halt/diminish IVD degeneration, cell therapy using different biomaterials e.g. hydrogels as cell carriers has been suggested. In this study, two different hydrogels were examined (in vitro) as potential cell carriers for human mesenchymal stem cells (hMSCs) intended for IVD transplantation. The aim was to investigate cell- survival and chondrogenic differentiation of hMSCs when cultured in hydrogels Puramatrix((R)) or Hydromatrix((R)) and potential effects of stimulation with growth hormone (GH). hMSCs/hydrogel cultures were investigated for cell-viability, attachment, gene expressionof chondrogenic markers SOX9, COL2A1, ACAN and accumulation of extracellular matrix (ECM). In both hydrogel types, hMSCs were viable for 28 days, expressed integrin beta 1 which indicates adhesion of hMSCs. Differentiation was observed into chondrocyte-like cells, in a higher extent in hMSCs/Hydromatrix((R)) cultures when compared to hMSCs/Puramatrix ((R)) hydrogel cultures. Gene expression analyses of chondrogenic markers verified results. hMSCs/hydrogel cultures stimulated with GH displayed no significant effects on chondrogenesis. In conclusion, both hydrogels, especially Hydromatrix((R)) was demonstrated as a promising cell carrier in vitro for hMSCs, when directed into chondrogenesis. This knowledge could be useful in biological approaches for regeneration of degenerated human IVDs.
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| 2620. |
- Hansson, Caroline, 1981, et al.
(författare)
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A possible association between panic disorder and a polymorphism in the preproghrelin gene
- 2013
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Ingår i: Psychiatry Research. - : Elsevier. - 0165-1781 .- 1872-7123. ; 206:1, s. 22-25
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Tidskriftsartikel (refereegranskat)abstract
- The aim of the study was to investigate whether polymorphisms in the preproghrelin gene are associated with anxiety disorders, such as panic disorder, in humans. Panic disorder is a severe anxiety disorder, characterized by sudden attacks of intense fear or anxiety in combination with somatic symptoms. The preproghrelin gene codes for two gut-derived circulating peptides that have been linked to anxiety-like behaviour in rodents: ghrelin (an orexigenic, pro-obesity hormone) and obestatin. In the present study, we genotyped three missense mutations in the preproghrelin gene in 215 patients suffering from panic disorder and in 451 controls. The A allele of the rs4684677 polymorphism was significantly associated with panic disorder, while there were no significant associations with the two other polymorphisms studied. We conclude that the rs4684677 (Gln90Leu) polymorphism in the preproghrelin gene may be associated with increased risk of panic disorder. It will be important to confirm these findings in additional panic disorder patient groups.
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