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- Öquist, G., et al.
(författare)
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Chlorophyll a fluorescence an alternative method for estimating primary production
- 1982
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Ingår i: Marine Biology. - 1230-7688. ; 68:1, s. 71-75
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Tidskriftsartikel (refereegranskat)abstract
- The in vivo chlorophyll a fluorescence index (F+DcM u-F-DcMu/F+DcMU) of natural waters was compared to the 14C-determined primary production, and the fluorescence intensity in the presence of 3-(3,4-dichlorophenyl)-l,l-dimethylurea (F + DCM~) was studied as a function of extracted and spectrophotometrically determined chlorophyll concentrations. Samples were taken every second week from May through October, 1979, at the station "Systrarna" situated in a coastal area of the Bottnian Sea. In addition, samples from the Archipelago Sea of the Baltic were collected on board the Finnish research vessel R/S "Aranda" during the September cruise 1979. The correlations between the fluorescence index and the 14C-determined primary production and between F+DcMu and total chlorophyll concentration were good when samples taken over short time intervals were compared. The shortcomings of both the fluorescence and the 14C methods are discussed. It is concluded that the fluorescence method is useful if it is desirable to follow with high time resolution any changes in the potential for photosynthesis (or pirmary production) in a water mass over relatively short time periods; e.g. during an algal bloom. The fluorescence method can furthermore be technically developed for automatic monitoring with a high time resolution. Efforts are being made in our laboratory to develop the method further to give information about the in situ rates of photosynthesis rather than the potential for photosynthesis in a phytoplankton population.
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- Norén, Jörgen G, 1947, et al.
(författare)
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Congenital hypothyroidism and changes in the enamel of deciduous teeth.
- 1983
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Ingår i: Acta paediatrica Scandinavica. - 0001-656X. ; 72:4, s. 485-9
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Tidskriftsartikel (refereegranskat)abstract
- Deciduous teeth from children with congenital hypothyroidism were collected and ground sections were prepared. The sections were analysed by means of polarized light and microradiography. The enamel in ground sections of deciduous teeth from children with congenital hypothyroidism showed an increase in areas with elevated pore volume distribution in both the pre- and postnatal enamel. The findings suggest that thyroid hormone influences enamel maturation. Further, alterations in enamel structure, presumably due to prenatal thyroid deficiency, were found to be more common among children with neurological abnormalities at the age of 7 to 9 years.
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