| 1. |
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| 2. |
- Carlson, Johan, et al.
(författare)
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Projekt: SCOPE Norra
- 2011
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Annan publikation (populärvet., debatt m.m.)abstract
- SCOPE Norra är ett samarbetskonsortium för forskning och utveckling tillsammans med massa- och pappersindustrin i Norrbotten och Västerbotten. Projektet koordineras av centrumbildningen ProcessIT Innovations.Inom SCOPE Norra pågår ett flertal delprojekt, uppdelat på ett antal fokusområden.Huvudfinansiär för konsortiet är Tillväxtverket genom medel från EU:s strukturfonder.
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| 3. |
- Hillarp, Andreas, et al.
(författare)
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Effects of the oral, direct factor Xa inhibitor rivaroxaban on commonly used coagulation assays
- 2011
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Ingår i: JOURNAL OF THROMBOSIS AND HAEMOSTASIS. - : Blackwell Publishing. - 1538-7933 .- 1538-7836. ; 9:1, s. 133-139
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Rivaroxaban is an oral direct factor Xa inhibitor developed for prophylaxis and treatment of thromboembolic disorders. Laboratory monitoring is not necessary but the dose-dependent effects on common reagents and assay procedures are largely unknown. Objectives: To investigate the effect of rivaroxaban on commonly used coagulation assays. Materials and Methods: Rivaroxaban was added to plasma from healthy subjects in the concentration range 0-1000 mu g L-1 and analyzed using different reagents for activated partial thromboplastin time (APTT), prothrombin time (PT), antithrombin, fibrinogen and activated protein C (APC) resistance assays. Results: At an expected peak concentration of rivaroxaban in clinical use, the APTTs were almost invariably prolonged but at lower concentrations the effect was weak. The concentration needed to double the APTT varied between 389 +/- 106 and 617 +/- 149 mu g L-1 for different reagents. The PT assays showed a marked degree of difference. In general, the Quick PT type assays were more sensitive compared with the Owren type PT assays. The results from antithrombin assays were dependent on the type of reagent, with the Xa-based assay being sensitive for rivaroxaban with an estimated increase of 0.09 IU mL-1 per 100 mu g L-1 rivaroxaban. There were only minor effects on fibrinogen assays based on thrombin reagents. The APTT-based assay for APC resistance is affected in a dose-dependent manner whereas an assay based on the activation of coagulation at the prothrombinase level was unaffected. Conclusions: Different assays, and even different reagents within an assay group, display variable effects by therapeutic concentrations of rivaroxaban.
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| 4. |
- Lindahl, Tomas, et al.
(författare)
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Effects of the oral, direct thrombin inhibitor dabigatran on five common coagulation assays
- 2011
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Ingår i: Thrombosis and Haemostasis. - : F K Schattauer Verlagsgesellschaft MBH. - 0340-6245 .- 2567-689X. ; 105:2, s. 371-378
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Tidskriftsartikel (refereegranskat)abstract
- Dabigatran is an oral, reversible thrombin inhibitor that has shown promising results in large clinical trials. Laboratory monitoring is not needed but the effects on common coagulation assays are incompletely known. Dabigatran was added to plasma from healthy subjects in the concentration range 0-1,000 μg/l and analysed using several reagents for activated thromboplastin time (APTT), prothrombin time (PT), fibrinogen, antithrombin, and activated protein C resistance. Typical trough concentrations are about 50 μg/l, peak concentrations 100-300 μg/l. At 100 μg/l all APTT-results were prolonged. The concentration required to double APTT ranged between 227 and 286 μg/l, the responses for all five reagents were similar. PT-reagents were much less affected with almost no samples above INR 1.2 at 100 μg/l. The effect was sample dilution dependent with PT Quick type more sensitive than PT Owren type methods. If a patient on dabigatran has prolonged APTT, >90 seconds, and Quick PT INR>2 or Owren PT INR>1.5 over-dosing or accumulation of dabigatran should be considered. Two of four fibrinogen reagents underestimated the fibrinogen concentration considerably at expected peak concentration. Methods based on inhibition of thrombin over-estimated the antithrombin concentration, but not Xa-based. The APC-resistance methods over-estimated the APC-ratio, which may lead to miss-classification of factor V Leiden patients as being normal. Different coagulation assays, and even different reagents within an assay group, display variable effects at therapeutic concentrations of dabigatran. Some of these assay variations are of clinical importance, thus knowledge is needed for a correct interpretation of results.
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| 5. |
- Linder, Tomas, et al.
(författare)
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Anisotropic light propagation in paper
- 2012
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Ingår i: Nordic Pulp & Paper Research Journal. - 0283-2631 .- 2000-0669. ; 27:2, s. 500-506
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Tidskriftsartikel (refereegranskat)abstract
- We investigate anisotropic light propagation in paper using both a theoretical model and experiments. The theoretical model utilizes the Monte Carlo method to solve the photon transport equation numerically. It is assumed that wood fibres are represented by infinitely long, homogeneous and straight cylinders. The layer-like microstructure and anisotropic orientation of the fibres is considered in the model. The conical scattering by cylindrical objects, the wood fibres, is argued as the main source of anisotropic scattering. Simulations revealed that laterally resolved transmittance exhibits directional dependence. Experiments on light transmitted through a standard kraft liner product confirmed that light in fact do propagate more in the machine direction than in the cross direction. Reasonably good agreement was obtained between experimentally and numerically obtained iso-intensity patterns.
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| 6. |
- Linder, Tomas
(författare)
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CMO1 encodes a putative choline monooxygenase and is required for the utilization of choline as the sole nitrogen source in the yeast Scheffersomyces stipitis (syn. Pichia stipitis)
- 2014
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Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 160, s. 929-940
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Tidskriftsartikel (refereegranskat)abstract
- Sixteen yeasts with sequenced genomes belonging to the ascomycete subphyla Saccharomycotina and Taphrinomycotina were assayed for their ability to utilize a variety of primary, secondary, tertiary and quartenary aliphatic amines as nitrogen sources. The results support a previously proposed pathway of quaternary amine catabolism whereby glycine betaine is first converted into choline, which is then cleaved to release trimethylamine, followed by stepwise demethylation of trimethylamine to release free ammonia. There were only a few instances of utilization of N-methylated glycine species (sarcosine and N,N-dimethylglycine), which suggests that this pathway is not intact in any of the species tested. The ability to utilize choline as a sole nitrogen source correlated strongly with the presence of a putative Rieske non-haem iron protein homologous to bacterial ring-hydroxylating oxygenases and plant choline monooxygenases. Deletion of the gene encoding the Rieske non-haem iron protein in the yeast Scheffersomyces stipitis abolished its ability to utilize choline as the sole nitrogen source, but did not affect its ability to use methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, ethanolamine or glycine as nitrogen sources. The gene was named CMO1 for putative choline monooxygenase 1. A bioinformatic survey of eukaryotic genomes showed that CMO1 homologues are found throughout the eukaryotic domain.
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| 7. |
- Linder, Tomas
(författare)
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Genomics of alternative sulfur utilization in ascomycetous yeasts
- 2012
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Ingår i: Microbiology. - : Microbiology Society. - 1350-0872 .- 1465-2080. ; 158, s. 2585-2597
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Tidskriftsartikel (refereegranskat)abstract
- Thirteen ascomycetous yeast strains with sequenced genomes were assayed for their ability to grow on chemically defined medium with 16 different sulfur compounds as the only significant source of sulfur. These compounds included sulfoxides, sulfones, sulfonates, sulfamates and sulfate esters. Broad utilization of alternative sulfur sources was observed in Komagataella pastoris (syn. Pichia pastoris), Lodderomyces elongisporus, Millerozyma farinosa (syn. Pichia sorbitophila), Pachysolen tannophilus, Scheffersomyces stipitis (syn. Pichia stipitis), Spathaspora passalidarum, Yamadazyma tenuis (syn. Candida tenuis) and Yarrowia lipolytica. Kluyveromyces lactis, Saccharomyces cerevisiae and Zygosaccharomyces rouxii were mainly able to utilize sulfonates and sulfate esters, while Lachancea thermotolerans and Schizosaccharomyces pombe were limited to aromatic sulfate esters. Genome analysis identified several candidate genes with bacterial homologues that had been previously shown to be involved in the utilization of alternative sulfur sources. Analysis of candidate gene promoter sequences revealed a significant overrepresentation of DNA motifs that have been shown to regulate sulfur metabolism in Sacc. cerevisiae.
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| 8. |
- Linder, Tomas, et al.
(författare)
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Lateral light scattering in fibrous media
- 2013
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Ingår i: Optics Express. - 1094-4087. ; 21:6, s. 7835-7840
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Tidskriftsartikel (refereegranskat)abstract
- Lateral light scattering in fibrous media is investigated by computing the modulation transfer function (MTF) of 22 paper samples using a Monte Carlo model. The simulation tool uses phase functions from infinitely long homogenous cylinders and the directional inhomogeneity of paper is achieved by aligning the cylinders in the plane. The inverse frequency at half maximum of the MTF is compared to both measurements and previous simulations with isotropic and strongly forward single scattering phase functions. It is found that the conical scattering by cylinders enhances the lateral scattering and therefore predicts a larger extent of lateral light scattering than models using rotationally invariant single scattering phase functions. However, it does not fully reach the levels of lateral scattering observed in measurements. It is argued that the hollow lumen of a wood fiber or dependent scattering effects must be considered for a complete description of lateral light scattering in paper.
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| 9. |
- Linder, Tomas
(författare)
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Light Scattering in Fiber-based Materials : a foundation for characterization of structural properties
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Deeper knowledge of light propagation in fiber-based materials is fundamental in order to understand their optical appearance as well as for industrial applications. Light scattering measurements are appropriate in handling dynamic industrial environments and can provide information regarding structural properties. In general, on-line property measurements are best utilized by establishing an understanding of the underlying physics and using that knowledge in an optimal way to determine the parameters or properties sought after. Light scattering is affected by numerous parameters such as size, shape, concentration and refractive index of the scattering particles as well as the waveleng th of the incident source. In addition, anisotropic light diffusion in media which have a directional-dependency, such as structured fiber-based materials, are neither well understood nor well investigated.By approximating cellulose fibers as infinitely long, straigth cylinders it is possible to use an analytical solution to Maxwell’s equations to describe the scattering characteristics such as phase functions and scattering efficiency. This makes it possible to utilize both the wave nature of light and structural properties of the fiber network when modelling multiple light scattering. The developed model solves the radiative transfer equation numerically using theMonte Carlo method resulting in a description of multiple scattering in a sphere-cylinder media.The results show that scattering media consisting of infinite long, straigth, homogeneous or hollow cylinders scatter light very differently as compared with a media consisting of spherical particles. Both scattered intensity and the degree of depolarization are affected by a strong forward scattering behavior observed for cylindrical particles. This strong forward scattering behavior was also found to enhance lateral scattering in paper, and therefore predicts a larger extent of lateral light scattering than models using rotationally invariant single scattering phase functions. A strong relationship between anisotropic diffusion and to degree of in-plane fiber orientation was also observed using both measurements and simulations. In conclusion, it was found that the approximation of cellulose fibers as infinitely long, straigth cylinders is reasonable when modelling scattering in paper. The findings indicate that parameters such as geometrical properties, particle composition, fiber orientation and fiber orientation variations can be measured by monitoring scattered light intensity. The obtained knowledge provides a base for further development of on-line sensing techniques that meet industrial requirements. Since the theory is general, it is likewise relevant and applicable to other areas of material science where imaging or remote sensing techniques are of interest.
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| 10. |
- Linder, Tomas, et al.
(författare)
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Light scattering in fibrous media with different degrees of in-plane fiber alignment
- 2014
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Ingår i: Optics Express. - 1094-4087. ; 22:14, s. 16829-16840
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Tidskriftsartikel (refereegranskat)abstract
- Fiber orientation is an important structural property in paper and other fibrous materials. In this study we explore the relation between light scattering and in-plane fiber orientation in paper sheets. Light diffusion from a focused light source is simulated using a Monte Carlo technique where parameters describing the paper micro-structure were determined from 3D x-ray computed tomography images. Measurements and simulations on both spatially resolved reflectance and transmittance light scattering patterns show an elliptical shape where the main axis is aligned towards the fiber orientation. Good qualitative agreement was found at low intensities and the results indicate that fiber orientation in thin fiber-based materials can be determined using spatially resolved reflectance or transmittance.
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| 11. |
- Linder, Tomas
(författare)
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Light scattering in pulp and paper
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The pulp and paper industry of today is facing a highly competitive market where manufacturers are constantly seeking ways to reduce costs as well as to improve product specifications and quality. On-line quality control is one of many areas being actively developed, from the wood delivered to the plant to the fibers in the finished product. In general, on-line property measurements are best utilized by establishing an understanding of the underlying physics and using that knowledge in an optimal way to determine the parameter or property sought for. One specific area of development is to determine fiber orientation in a paper sheet. The fiber orientation is set by the production Process and is an important parameter since it defines e.g. strength and Optical properties of the paper. In the paper mill today, improvements can be made if the fiber orientation could be determined on-line and in real time. One way of doing this is to use non-contact, full-optical techniques to determine the light scattering pattern in a paper sheet. The objective of this work is to determine the properties of light scattering in paper and how this knowledge could be utilized in extracting information on the properties of paper.A numerical model utilizing light scattering in a sphere-cylinder medium is presented. The simulated medium can represent scattering in both wood pulp and paper. Wood fibers are represented as long, straight cylinders and smaller particles, like fines, are represented as small spherical particles. Scattering from fibers are determined by an analytical solution of Maxwell’s equations for scattering on infinitely long cylinders. The small spherical particles are described by Mie theory. Fibers can have random orientation as in the case of pulp, or aligned orientation as in paper. The layer-like anisotropic microstructure in paper is considered in the model. The model also employ the Stokes-Mueller formalism for the scattering particles, making the state of polarization possible to track.The effects of varying volume concentration and size of the scattering components on reflection, transmission and polarization of the incident light are investigated. The findings on the differences in depolarization and its spatial distribution opens for techniques that enables the relative proportions of fibers and fines in pulp to be determined.For aligned fiber structures it is shown both theoretically and experimentally that spatially resolved reflectance and transmittance exhibits directional dependence. This information could possibly be used in a robust, rapid and cheap device for on-line characterization in the paper production process.
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| 12. |
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| 13. |
- Linder, Tomas, et al.
(författare)
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Monte Carlo simulation of photon transport in a randomly oriented sphere-cylinder scattering medium
- 2011
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Ingår i: Applied physics. B, Lasers and optics (Print). - : Springer Science and Business Media LLC. - 0946-2171 .- 1432-0649. ; 105:3, s. 659-664
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Tidskriftsartikel (refereegranskat)abstract
- A Monte Carlo simulation tool for simulating photon transport in a randomly oriented sphere-cylinder medium has been developed. The simulated medium represents a paper pulp suspension where the constituents are assumed to be mono-disperse micro-spheres, representing dispersed fiber fragments, and infinitely long, straight, randomly oriented cylinders representing fibers. The diameter of the micro-spheres is considered to be about the order of the wavelength and is described by Mie scattering theory. The fiber diameter is considerably larger than the wavelength and the photon scattering is therefore determined by an analytical solution ofMaxwell’s equation for scattering at an infinitely long cylinder. By employing a Stokes–Mueller formalism, the software tracks the polarization of the light while propagating through the medium. The effects of varying volume concentrations and sizes of the scattering components on reflection, transmission and polarization of the incident light are investigated. It is shown that not only the size but also the shape of the particles has a big impact on the depolarization.
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| 14. |
- Magnusson, Maria, et al.
(författare)
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The international normalized ratio according to Owren in liver disease: Interlaboratory assessment and determination of international sensitivity index
- 2013
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Ingår i: Thrombosis Research. - : Elsevier. - 0049-3848 .- 1879-2472. ; 132:3, s. 346-351
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The international normalized ratio (INR) is used to prioritize liver disease patients for transplantation. Previous studies have shown high interlaboratory variability in Quick-based INR determinations in samples of patients with liver disease. We assessed Owren-based INR reagents for analyzing INR in patients with liver disease. Further, we determined the difference between international sensitivity index (ISI) for patients on vitamin K antagonists (ISIVKA) and ISI for patients with liver disease (ISIliver). less thanbrgreater than less thanbrgreater thanPatients and Methods: Twenty patients with liver disease were included, 10 with INR 1.8-3.6 (group A1) and 10 with INR 1.2-1.5 (group C1). Plasma from these patients was analyzed for Owren-based INR in eight Swedish laboratories using either of following reagents: SPA+, Owrens PT or Nycotest PT. To determine ISI liver, the reference thromboplastin RBT/05 and additional 41 patients with liver disease and 20 normal controls were included. ISIVKA was determined according to the WHO procedure. The difference between the ISIVKA and ISIliver was calculated. less thanbrgreater than less thanbrgreater thanResults: The coefficients of variance for the Owren based INR methods were 6.2% in group A1, 3.9 % in group C1 and 5.3% for all patients. The difference between ISIVKA and ISIliver were -0.4%, -0.7% and -0.2% for SPA+, Owrens PT and Nycotest PT respectively. less thanbrgreater than less thanbrgreater thanConclusions: Interlaboratory variation in INR analyses according to Owren in patients with liver disease is low and the difference between ISIVKA and ISIliver is below 10% with this method. ISIVKA can therefore be used in the INR calibration, for the Owren reagents studied, when analyzing plasma from patients with liver disease.
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| 15. |
- Nilsson, Olof, et al.
(författare)
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ABC om främmande kropp i luftvägarna
- 2012
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 109:51-52, s. 2361-2365
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 16. |
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| 17. |
- Steinhauf, Daniel, et al.
(författare)
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Silencing Motifs in the Clr2 Protein from Fission Yeast, Schizosaccharomyces pombe
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:1, s. e86948-
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Tidskriftsartikel (refereegranskat)abstract
- The fission yeast, Schizosaccharomyces pombe, is a well-established model for heterochromatin formation, but the exact sequence of events for initiation remains to be elucidated. The essential factors involved include RNA transcribed from repeated sequences together with the methyltransferase Clr4. In addition, histone deacetylases, like Clr3, found in the SHREC complex are also necessary for transcriptional silencing. Clr2 is another crucial factor required for heterochromatin formation found in the SHREC complex. The function of Clr2 has been difficult to establish due to the lack of conserved domains or homology to proteins of known molecular function. Using a bioinformatics approach, three conserved motifs in Clr2 were identified, which contained amino acids important for transcriptional repression. Analysis of clr2 mutant strains revealed a major role for Clr2 in mating-type and rDNA silencing, and weaker effects on centromeric silencing. The effect on mating-type silencing showed variegation in several of the strains with mutated versions of Clr2 indicating an establishment or maintenance defect. Moreover, the critical amino acids in Clr2 were also necessary for transcriptional repression in a minimal system, by the tethering of Clr4 upstream of a reporter gene, inserted into the euchromatic part of the genome. Finally, in silico modeling suggested that the mutations in Clr2 cause disruption of secondary structures in the Clr2 protein. Identification of these critical amino acids in the protein provides a useful tool to explore the molecular mechanism behind the role of Clr2 in heterochromatin formation.
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| 18. |
- Svanström, Erika, et al.
(författare)
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Analytical one-dimensional model for laser-induced ultrasound in planar optically absorbing layer
- 2014
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Ingår i: Ultrasonics. - : Elsevier BV. - 0041-624X .- 1874-9968. ; 54:3, s. 888-893
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Tidskriftsartikel (refereegranskat)abstract
- Ultrasound generated by means of laser-based photoacoustic principles are in common use today and applications can be found both in biomedical diagnostics, non-destructive testing and materials characterisation. For certain measurement applications it could be beneficial to shape the generated ultrasound regarding spectral properties and temporal profile. To address this, we studied the generation and propagation of laser-induced ultrasound in a planar, layered structure. We derived an analytical expression for the induced pressure wave, including different physical and optical properties of each layer. A Laplace transform approach was employed in analytically solving the resulting set of photoacoustic wave equations. The results correspond to simulations and were compared to experimental results. To enable the comparison between recorded voltage from the experiments and the calculated pressure we employed a system identification procedure based on physical properties of the ultrasonic transducer to convert the calculated acoustic pressure to voltages. We found reasonable agreement between experimentally obtained voltages and the voltages determined from the calculated acoustic pressure, for the samples studied. The system identification procedure was found to be unstable, however, possibly from violations of material isotropy assumptions by film adhesives and coatings in the experiment. The presented analytical model can serve as a basis when addressing the inverse problem of shaping an acoustic pulse from absorption of a laser pulse in a planar layered structure of elastic materials.
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| 19. |
- Svanström, Erika, et al.
(författare)
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Combined physical and statistical modeling of laser induced ultrasound signals from thin light absorbing films
- 2013
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Ingår i: 2013 IEEE International Ultrasonics Symposium. - Piscataway, NJ : IEEE Communications Society. - 9781467356848 ; , s. 2167-2170
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Konferensbidrag (refereegranskat)abstract
- This paper presents a method for predicting the ultrasound pulses generated by thin semi-transparent polymer films, excited by a short laser pulse. The acoustic pressure is first modeled based on the physical properties of the polymer. Partial Least-Squares Regression is then used to link the model pressure to the ultrasound pulses measured by an ultrasound transducer. The uncertainty of the regression is also simulated, showing that the method is robust to noise in the measurements
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