| 1. |
- Brockstedt, Sara, et al.
(författare)
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Vertical field MR imaging of upper thorax and spine in small children. Evaluation of a new surface coil
- 1993
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Ingår i: Acta Radiologica. - 1600-0455. ; 34:6, s. 549-553
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Tidskriftsartikel (refereegranskat)abstract
- To improve image quality in a vertical field MR imaging unit, operating at low field strength (0.3 T), we have designed a half-elliptical coil for use in the upper thoracic region of small children. Our intention was also to shorten the examination time, which until now has been long, because several scans with different coils have been necessary to cover the thoracic region. The experimental coil is designed so that a child's shoulders fit into the central region. The coil consists of 2 serially connected cable-loops, mounted on a foam rubber vest. The coil performance was tested in a phantom and improvements relative to standard coils were demonstrated in in vivo studies. The results indicate that by using the half-elliptical coil, the signal-to-noise (S/N) ratio can be improved by a factor of 2 to 3 in the thoracic region of a child.
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| 2. |
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| 3. |
- Weber, G, et al.
(författare)
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The phospholipase C b 3 gene located in the MEN 1 region shows loss of expression in endocrine tumors
- 1994
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Ingår i: Human Molecular Genetics. - : Oxford University Press (OUP). - 0964-6906 .- 1460-2083. ; 3:10, s. 1775-1781
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Tidskriftsartikel (refereegranskat)abstract
- Oncogenesis of tumours related to multiple endocrine neoplasia type 1 (MEN1) is associated with somatic deletions involving the MEN1 locus, suggesting inactivation of a tumour suppressor gene in this region. Identification of meiotic cross-overs in MEN1 families has placed the MEN1 locus centromeric of D11S807. An extended deletion mapping was performed in 27 primary parathyroid tumours, and identified D11S427 as the closest centromeric flanking marker. Through physical mapping using newly isolated cDNA clones, we estimated the distance between the flanking markers D11S807 and D11S427 to be less than 900 kb. One of these cDNA clones showed expression of a 4.4 kb message in multiple tissues, including those affected in MEN1, while in five endocrine tumours no transcript was detected. Sequence characterization showed that this gene encodes for the phospholipase C beta 3, a key enzyme in signal transduction.
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| 4. |
- Wyller, J., et al.
(författare)
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Burger's equation as a model for the IP phenomenon
- 1992
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Ingår i: Geophysical Prospecting. - : Wiley. - 0016-8025 .- 1365-2478. ; 40:3, s. 325-341
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Tidskriftsartikel (refereegranskat)abstract
- The dynamic response characterizing the induced-polarization (IP) phenomenon is modelled by a nonlinear diffusion equation (Burger's equation) supplemented by relevant initial and boundary values. The analysis of the model yields a voltage step response and an impedance curve in the frequency domain which agree qualitatively with experimental measurements. Curve fits based on the model have been made in the case of electrochemical cell measurements. The diffusion coefficients estimated by means of these curves are of the same order of magnitude as those calculated using experimental measurements. The normalized transient with these diffusion coefficients agrees with observations, but probably has a shorter discharge time. We have also carried out a comparison with predictions obtained from a linear, finite diffusion layer model, thus showing that for most practical situations the nonlinear term modelling the migration effect can be neglected
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