| 1. |
- Carlson, Johan, et al.
(författare)
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A noise-tolerant group delay estimator applied to dispersion measurement in gases
- 2003
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Ingår i: Proceedings, 2003 IEEE Ultrasonics Symposium. - Piscataway, NJ : IEEE Communications Society. - 0780379225 ; , s. 254-257
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Konferensbidrag (refereegranskat)abstract
- In this paper we present a model-based group velocity estimator, that can be used to measure speed of sound in ultrasonic pulse-echo systems as a function of ultrasound frequency. The estimation of group velocities involves numerical differentiation of the phase difference. In the presence of noise, this becomes numerically unstable. The model-based approach presented herein, shows better tolerance to experimental noise. The performance of the estimator is evaluated with simulations as function of pulse bandwidth and SNR. Finally, the estimator applied to real data and compared with other methods for measuring speed of sound in Ethane and Oxygen.
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| 2. |
- Carlson, Johan, et al.
(författare)
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A simple scattering model for measuring particle mass fractions in multiphase flows
- 2002
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Ingår i: Ultrasonics. - 0041-624X .- 1874-9968. ; 39:8, s. 585-590
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a simple theoretical model of how pulsed ultrasound is attenuated by the particles in a solid/liquid flow. The theoretical model is then used to predict the attenuation of sound, given the mass fraction, the density, and the size distribution of the solid particles. The model is verified experimentally for suspensions of 0–10% (by mass) Dolomite ((Ca,Mg)CO3) particles and water. The experimental results show that the attenuation of sound due to particles varies linearly with mass fraction, and that the proposed theoretical model can be used to predict this attenuation. In all experiments the transmitter and receiver array were clamped onto the pipe wall, thus providing a completely non-invasive and non-intrusive measurement technique.
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| 3. |
- Carlson, Johan, et al.
(författare)
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Ultrasonic measurement of molar fractions in gas mixtures by orthogonal signal correction
- 2004
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Ingår i: 2004 IEEE Ultrasonics Symposium. - Piscataway, NJ : IEEE Communications Society. - 0780384121 ; , s. 821-825
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Konferensbidrag (refereegranskat)abstract
- Within Sweden and the EU, an increased use of biogas and natural gas is encouraged. To support more effective manufacturing, distribution, and consumption of energy gases, new methods for the measurement of the calorimetric value or the gas composition are needed. In this paper, we present a method to quantify variation in ultrasound pulse shape, caused by interaction effects between the constituents of a two-component gas mixture. The method is based on a combination of principal component analysis and orthogonal signal correction. Experiments on mixtures of oxygen and ethane show that the extracted information correlates well with the molar fraction of ethane in the mixture.
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| 4. |
- Fagman, Henrik, 1975, et al.
(författare)
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Nuclear accumulation of full-length and truncated adenomatous polyposis coli protein in tumor cells depends on proliferation.
- 2003
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 0950-9232 .- 1476-5594. ; 22:38, s. 6013-22
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Tidskriftsartikel (refereegranskat)abstract
- The adenomatous polyposis coli (APC) tumor suppressor is a nucleocytoplasmic protein. The nuclear accumulation of APC was recently found to vary depending on cell density, suggesting that putative APC function(s) in the nucleus is controlled by the establishment of cell contacts. We report here that the density-dependent redistribution of APC between nucleus and cytoplasm prevails in 6/6 thyroid and colorectal carcinoma cell lines. Moreover, mutated APC lacking known nuclear localization sequences had the similar distribution pattern as the full-length protein. APC invariably accumulated in the nuclei of Ki-67 expressing cells, but was largely cytoplasmic when cell cycle exit was induced by serum starvation or at high cell density. APC colocalized with beta-catenin in the nucleus only in one cell line (SW480). Also, APC maintained a predominantly nuclear position in early confluent states when cytoplasmic beta-catenin was recruited to newly formed adherens-like junctions. The results indicate that nuclear targeting of APC is driven by cell cycle entry rather than altered cell-cell contact. The ability of C-terminally truncated APC to accumulate in the nucleus suggests that nuclear import signals other than NLS1(APC) and NLS2(APC) are functionally important. Residual function(s) of N-terminal APC fragments in tumor cells carrying APC mutations might be beneficial to tumor growth and survival.
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| 5. |
- Martinsson, Johan, 1975
(författare)
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De-nationalising economic effects
- 2003
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Ingår i: European Consortium for Political Research joint sessions, Edinburgh, UK, March 28-April 2.
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Konferensbidrag (refereegranskat)
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| 6. |
- Martinsson, Johan, 1975
(författare)
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Den svenska nätopinionen
- 2001
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Ingår i: i Holmberg, S. och Weibull, L. (red.) Land, Du välsigande? SOM-rapport nr 26. SOM-institutet.. - Göteborg : University of Gothenburg. - 9197367060 ; , s. 311-322
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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