| 251. |
- Sandström, Monica, 1946-, et al.
(författare)
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Power frequency magnetic fields and computer monitor instability
- 1998
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Ingår i: Displays (Guildford). - : Elsevier. - 0141-9382 .- 1872-7387. ; 19:2, s. 85-90
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Tidskriftsartikel (refereegranskat)abstract
- Owing to the increased use of electronic loads, the harmonic content of the magnetic field in buildings has increased and it is therefore of interest to study how the harmonics (i.e. 150 Hz magnetic fields) will affect the stability of the picture on the monitor screen. Another frequency of interest to study is 16.7 Hz, the frequency used by the Swedish railway. Ten volunteers were asked to judge the occurrence of jitter on a 15-in. color monitor screen, refresh rate 72.2 Hz, at different amplitudes and frequencies of the vertical applied magnetic field. The tested screen had a highest sensitivity to 150 Hz external magnetic field, followed by 60, 16.7 and 50 Hz. In a static magnetic field the screen had a sensitivity (displacement) of 0.031±0.006 mm per applied microtesla.
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| 252. |
- Satherberg, A, et al.
(författare)
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Calculation of photon energy and dose distributions in a 50 MV scanned photon beam for different target configurations and scan patterns
- 1998
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Ingår i: Medical physics (Lancaster). - 0094-2405. ; 25:2, s. 236-240
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Tidskriftsartikel (refereegranskat)abstract
- A method to characterize the energy distribution in the whole photon field is valuable when designing an accelerator for choosing target and flattening filter or scan pattern. Another field of application is beam characterization for treatment planning systems or other dosimetric purposes. This work is focused on the energy distribution in different 50 MV bremsstrahlung beams with different scanning of electrons on three different targets. Fluence differential in energy and angle at the exit of each target has been determined by Monte Carlo calculations for a narrow beam. Data for broad beams were obtained by convolution of the narrow beams with different scan patterns. Photon energy fluence differential in energy at SSD 100 were thus found to be rather different for the targets studied. The results are presented as mean energy profiles and narrow beam half-value layer (HVL) in water. Two different experimental setups were used to measure HVL at the central axis and at off-axis positions. The two methods gave results which differ by 5%-6% and the calculated data where within these experimental results. In conclusion, the presented method for characterization of the photon field energy distribution is well within the experimental results and can thus be used to improve accelerator design or dosimetric calculations, e.g., for treatment planning. (C) 1998 American Association of Physicists in Medicine.
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| 253. |
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| 254. |
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| 255. |
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| 256. |
- Seo, M., et al.
(författare)
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Higher activity of an aldehyde oxidase in the auxin-overproducing superroot1 mutant of Arabidopsis thaliana
- 1998
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Ingår i: Plant Physiology. - : Oxford University Press (OUP). - 0032-0889 .- 1532-2548. ; 116:2, s. 687-693
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Tidskriftsartikel (refereegranskat)abstract
- Aldehyde oxidase (AO; EC 1.2.3.1) activity was measured in seedlings of wild type or an auxin-overproducing mutant, superroot1 (sur1), of Arabidopsis thaliana. Activity staining for AO after native polyacrylamide gel electrophoresis separation of seedling extracts revealed that there were three major bands with AO activity (AO1-3) in wild-type and mutant seedlings. One of them (AO1) had a higher substrate preference for indole-3-aldehyde. This AO activity was significantly higher in sur1 mutant seedlings than in the wild type. The difference in activity was most apparent 7 d after germination, the same time required for the appearance of the remarkable sur1 phenotype, which includes epinastic cotyledons, elongated hypocotyls, and enhanced root development. Higher activity was observed in the root and hypocotyl region of the mutant seedlings. We also assayed the indole-3-acetaldehyde oxidase activity in extracts by high-performance liquid chromatography detection of indole-3-acetic acid (IAA). The activity was about 5 times higher in the extract of the sur1 seedlings, indicating that AO1 also has a substrate preference for abscisic aldehyde. Treatment of the wild-type seedlings with picloram or IAA caused no significant increase in AO1 activity. This result suggested that the higher activity of AO1 in sur1 mutant seedlings was not induced by IAA accumulation and, thus, strongly supports the possible role of AO1 in IAA biosynthesis in Arabidopsis seedlings.
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| 257. |
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| 258. |
- Sjogren, R, et al.
(författare)
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Influence of electron contamination on in vivo surface dosimetry for high-energy photon beams
- 1998
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Ingår i: Medical physics (Lancaster). - 0094-2405. ; 25:6, s. 916-921
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Tidskriftsartikel (refereegranskat)abstract
- The influence of the electron contamination at in vivo dosimetry with diodes on the patient surface has been investigated by introducing different accessories in the beam path and by changing the field size and SSD. The results show a clear correlation between the electron contamination at an effective measuring depth of the diode and the signal from the patient diode. When the electron contamination is taken into account the agreement between the diode values and the absorbed dose is greatly improved. More accurate in vivo dosimetry with less error margins is therefore possible if better predictions of the electron contamination in high-energy photon beams can be performed. (C) 1998 American Association of Physicists in Medicine. [S0094-2405(98)00606-3].
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| 259. |
- Sjögren, G, et al.
(författare)
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A 5-year clinical evaluation of ceramic inlays (Cerec) cemented with a dual-cured or chemically cured resin composite luting agent.
- 1998
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Ingår i: Acta Odontologica Scandinavica. - 0001-6357 .- 1502-3850. ; 56:5, s. 263-7
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Tidskriftsartikel (refereegranskat)abstract
- Sixty-six class-II CAD/CAM-manufactured ceramic inlays (Cerec) were placed in 27 patients. Each patient received at least one inlay luted with a dual-cured resin composite and one inlay luted with a chemically cured resin composite. The inlays were examined 5 years after luting using the California Dental Association (CDA) criteria. Eighty-nine percent of the 66 inlays were rated 'satisfactory'. During the follow-up period replacement was required for 3 inlays because of inlay fractures (4.5%) and 1 inlay because of fracture of the tooth substance (1.5%). All those inlays were luted with the dual-cured resin composite luting agent. Of the remaining 62 inlays the CDA rating 'excellent' was given to 84% for color, 97% for surface, and 81% for anatomic form. 'Excellent' margin integrity was seen in 52% of the dual-cured resin composite luted inlays and in 61% of the chemically cured resin composite luted inlays. No statistically significant (P> 0.05) difference was observed between the two luting agents.
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| 260. |
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