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- Harms-Ringdahl, K, et al.
(författare)
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Assessment of jet pilots' upper trapezius load calibrated to maximal voluntary contraction and a standardized load.
- 1996
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Ingår i: Journal of Electromyography & Kinesiology. - : Elsevier BV. - 1050-6411 .- 1873-5711. ; 6:1, s. 67-72
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Tidskriftsartikel (refereegranskat)abstract
- Electromyographic (EMG) recording of the myoelectrical activity level in the trapezius muscle is often used as one method of assessing neck and shoulder muscle workload. To analyse how the normalization value influences interpretation of upper trapezius load during a work task, two different reference values for normalization were applied - one obtained during a maximum voluntary contraction (MVE) and the other during a standardized muscular load (RVE). Nine jet pilots (ages 30-48 yr) flew two sorties in a 37 Viggen aircraft using either of two types of head garment while 3-D acceleration and muscular activity were recorded. In each sortie twice in the programme a steep left turn at 5-6 +G(Z) was performed. The highest activity level (MVE) obtained during shoulder elevation combined with an isometric heavy resistance (maximum) against arm flexion/abduction was used as one normalization value. Before, between, and after the two flights, 15 s EMG recordings (RVE) during a dumbbell test in the same arm position were also taken. The muscular activity in the upper trapezius during a given task varied a great deal between individuals, but the reliability of the amplitude levels on different occasions during a work day was good, given the same electrode location and application. If muscular activity during a standardized loading force (e.g. dumbbell test) is used to normalize the recordings for workload assessments related to utilized muscular capacity, a subject with high muscular strength and comparatively low workload might in some situations be assessed as having the same workload as, or a higher load than a subject with less strength and a comparatively high workload. While normalization using a standardized force can be used to assess changes in workload, for assessing workload related to the individual's capacity recording the myoelectrical activity during maximal contraction is preferable.
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| 2. |
- Pettersson, Håkan, 1956-, et al.
(författare)
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Summary of IAEA-MEL's investigation of Kara Sea radioactivity and radiological assessment
- 1997
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Ingår i: Marine Pollution Bulletin. - 0025-326X .- 1879-3363. ; 35:7-12, s. 235-241
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Tidskriftsartikel (refereegranskat)abstract
- IAEA-MEL participated in five expeditions to the Kara Sea with the aim of assessing the radiological consequences of dumped radioactive wastes in the Novaya Zemlya Bays and Trough. The programme included sampling, in-situ underwater investigations, laboratory analyses of water, sediment and biota samples, the development of a marine radioactivity database, modelling and radiological assessment, the organization of intercomparison exercises and the evaluation of distribution coefficients. Radiometric investigations have shown that no radiologically significant environmental contamination has occurred. Leakages which have led to locally increased levels of radionuclides in sediment have only been observed in Stepovoy and Abrosimov Bays. Computer modelling results suggest that only radiological effects on local and regional scales may be of importance. The global radiological impact of the disposals in the Arctic Seas will be negligible.
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| 3. |
- Belyaev, I Y, et al.
(författare)
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Effects of ethidium bromide on DNA loop organisation in human lymphocytes measured by anomalous viscosity time dependence and single cell gel electrophoresis
- 1999
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Ingår i: Biochimica et Biophysica Acta - General Subjects. - 0304-4165 .- 1872-8006. ; 1428:2-3, s. 348-356
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Tidskriftsartikel (refereegranskat)abstract
- The effects of ethidium bromide (EtBr) on human lymphocytes were studied by the method of anomalous viscosity time dependence (AVTD) and by the comet assay. EtBr at low concentrations increased the maximum viscosity and time of radial migration as measured with AVTD at neutral conditions of lysis. A pronounced relaxation of DNA loops was observed with the neutral comet assay. The maximal comet length corresponded to 2 Mb DNA loops. At high concentrations of EtBr, 2. mg/ml, significant reduction in AVTD below control level was seen that suggested hypercondensation of chromatin. The hypercondensation was directly observed with the neutral comet assay. EtBr did not induce DNA strand breaks as measured by the alkaline comet assay. The hypercondensed nuclei could be decondensed by irradiation with gamma-rays or exposure to light. The data provide evidence that EtBr at high concentrations resulted in hypercondensation of chromatin below control level. The comet assay confirmed that the increase in AVTD peaks deals with relaxation of loops and AVTD decrease is caused by chromatin condensation. The prediction of the AVTD theory for a correlation between time of radial migration and condensation of chromatin was verified. Further, the data show that the comet assay at neutral conditions of lysis is rather sensitive to DNA loop relaxation in the absence of DNA damage. Finally, donor specificity was found for the hypercondensation.
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