| 1. |
- Ohlson, Sten, et al.
(författare)
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Weak affinity chromatography
- 1993. - 1
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Ingår i: Handbook of affinity chromatography. - New York : Marcel Dekker. - 0824789393 ; , s. 299-314
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Eriksson, Håkan, et al.
(författare)
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A robust correlation receiver for distance estimation
- 1994
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Ingår i: IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control. - New York : Institute of Electrical and Electronics Engineers (IEEE). - 0885-3010 .- 1525-8955. ; 41:5, s. 596-603
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Tidskriftsartikel (refereegranskat)abstract
- Many methods for distance estimation, such as the ultrasonic pulse-echo method, involve the estimation of a time-of-flight (TOF). In this paper, a signal model is developed that, apart from the TOF, accounts for an unknown, linear frequency dependent distortion as well as for additive noise. We derive a TOF estimator for this model based on the criteria of maximum likelihood. The resulting receiver can be seen as an extension or generalization of the well known cross-correlation, or "matched filter", estimator described, e.g., by Nilsson. The novel receiver is found to be more robust against unknown pulse shape distortion than the cross-correlation estimator, giving less biased TOF estimates. Also, bias versus noise sensitivity can be controlled by proper model order selection
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| 3. |
- Sundström, N., et al.
(författare)
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Registration of surface structures using airborne focused ultrasound
- 1991
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Ingår i: Ultrasound in Medicine and Biology. - : Elsevier BV. - 0301-5629 .- 1879-291X. ; 17:5, s. 513-518
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Tidskriftsartikel (refereegranskat)abstract
- A low-cost measuring system, based on a personal computer combined with standard equipment for complex measurements and signal processing, has been assembled. Such a system increases the possibilities for small hospitals and clinics to finance advanced measuring equipment. A description of equipment developed for airborne ultrasound together with a personal computer-based system for fast data acquisition and processing is given. Two air-adapted ultrasound transducers with high lateral resolution have been developed. Furthermore, a few results for fast and accurate estimation of signal arrival time are presented. The theoretical estimation models developed are applied to skin surface profile registrations
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| 4. |
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| 5. |
- Braide, M, et al.
(författare)
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Migration of human granulocytes in filters: effects of gravity and movable gradients of f-MLP
- 1994
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Ingår i: Biorheology. - THE BOULEVARD, LANGFORD LANE, KIDLINGTON, OXFORD, ENGLAND OX5 1GB : PERGAMON-ELSEVIER SCIENCE LTD. - 0006-355X .- 1878-5034. ; 31:6, s. 617-630
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Tidskriftsartikel (refereegranskat)abstract
- The Boyden chamber technique for chemotaxis uses a mesh filter that constitutes a matrix for cell locomotion and, at the same time, creates a local restriction for convective fluid movements that allows the establishment of a diffusive concentration gradient of chemotactic substance in the filter. In the present study, the Boyden chamber was modified by the introduction of a filter sandwich that allowed cell migration both upwards and downwards and by the use of a fluid density gradient controlling cell buoyancy and mechanically supporting a movable chemotactic gradient. This method was used to study chemotaxis and random migration of human granulocytes under the influence of gravitational forces and movable gradients of f-MLP. The results show that gravity affected cell motion significantly during random migration but not during chemotaxis. The rate of chemotactic migration was dependent on the steepness of the spatio-temporal f-MLP gradients. A stationary spatial gradient produced less migration than a gradient that was slowly moved through the filter sandwich in a direction opposite to that of the cell migration. The presence of f-MLP at constant concentration caused a minor, statistically insignificant, increase of the rate of random migration.
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| 6. |
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| 7. |
- Löfgren, Anders, et al.
(författare)
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Copolymers of 1,5-dioxepan-2-one and L- or D,L-dilactide: in vivo degradation behaviour
- 1994
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Ingår i: Journal of Biomaterials Science. Polymer Edition. - 0920-5063. ; 6:5, s. 411-423
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Tidskriftsartikel (refereegranskat)abstract
- Copolymers of 1,5-dioxepan-2-one (DXO) and L- or D,L-dilactide have been synthesized and characterized. The molar ratio of the two monomers was around 20/80 of DXO and L- or D,L-lactide respectively. In vivo studies on rats revealed significant differences in tissue response between the semicrystalline DXO/L-LA copolymer and the amorphous DXO/D,L-LA copolymer. The materials were characterized pre- and post-implantation by size-exclusion chromatography (SEC), differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), and light-microscopy. Degradation seems to follow an autocatalytic hydrolysis mechanism. The amorphous copolymer was degraded at a faster rate and gave a less pronounced foreign body reaction as compared to the semicrystalline one.
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