| 1. |
- Brändström, U., et al.
(författare)
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Results from the intercalibration of optical low light calibration sources 2011
- 2012
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Ingår i: Geoscientific Instrumentation, Methods and Data Systems. - : Copernicus GmbH. - 2193-0856 .- 2193-0864. ; 1:1, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- Following the 38th Annual European Meeting onAtmospheric Studies by Optical Methods in Siuntio in Finland,an intercalibration workshop for optical low light calibrationsources was held in Sodankyl¨a, Finland. The mainpurpose of this workshop was to provide a comparable scalefor absolute measurements of aurora and airglow. All sourcesbrought to the intercalibration workshop were compared tothe Fritz Peak reference source using the Lindau CalibrationPhotometer built by Wilhelm Barke and Hans Lauche in1984. The results were compared to several earlier intercalibrationworkshops. It was found that most sources were fairlystable over time, with errors in the range of 5–25 %. To furthervalidate the results, two sources were also intercalibratedat UNIS, Longyearbyen, Svalbard. Preliminary analysis indicatesagreement with the intercalibration in Sodankyl¨a withinabout 15–25 %.
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| 2. |
- Berndtsson, R., et al.
(författare)
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The effects of storm water on Lake Vaxjosjon
- 1989
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Ingår i: Vatten: tidskrift för vattenvård /Journal of Water Management and research. - 0042-2886. ; 45:2, s. 167-173
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present study was to determine the pollution load originating from storm water on Lake Vaxjosjon. Each year about 1,050,000 m3 of storm water are discharged into the lake. Storm water represents a substantial pollution source for the lake and therefore also a main reason for the hypertrophic conditions in the lake. In order to evaluate the effects of the discharged storm water on the ecological conditions in the lake, an investigation was carried out using available information on storm water quality together with complementary sampling and flow measurements. Two different time scales were considered to be important: a short time scale for evaluating effects on the receiving waters due to shock loads of toxic substances (hours and days) and a long time scale for evaluating the effects of nutrients (years). In order to investigate effects concerning the short time scale, a computer-based runoff model was used. For the long time scale a daily precipitation series from 1970 to 1983 was used. The results showed that approximately 37% of the annual load of total phosphorus and 70% of the annual load of total nitrogen originate from storm water. Also a considerable portion of the annual heavy metal load originates from storm water (zink 51%, copper 55%). The annual total phosphorus load on Lake Vaxjosjon is 0.63 g/m2 lake area and year. The storm water part represents a phosphorus load equal to 0.23 g/m2 lake area and year. The acceptable load of phosphorus, for mesotrophic conditions in the lake, is about 0.2 g/m2 lake area and year. In order to improve the water quality in Lake Vaxjosjon sediment dredging of the bottom sediments needs to be undertaken. The sediments consists of an organic rich, phosphorus and nitrogen accumulated, black, anaerobic deposit, causing internal nutrient loading during summer periods.
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| 3. |
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| 4. |
- Yamauchi, M, et al.
(författare)
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Ionospheric Response Observed by EISCAT During the 6–8 September 2017 Space Weather Event : Overview
- 2018
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Ingår i: Space Weather. - : John Wiley & Sons. - 1542-7390. ; 16:9, s. 1437-1450
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Tidskriftsartikel (refereegranskat)abstract
- We present ionospheric plasma conditions observed by the EISCAT radars in Tromsø and on Svalbard, covering 68°–81° geomagnetic latitude, during 6–8 September 2017. This is a period when X2.2 and X9.3 X‐ray flares occurred, two interplanetary coronal mass ejections (ICMEs) arrived at the Earth accompanied by enhancements of MeV‐range energetic particle flux in both the solar wind (SEP event) and inner magnetosphere, and an AL < −2,000 substorm took place. (1) Both X flares caused enhancement of ionospheric electron density for about 10 min. The X9.3 flare also increased temperatures of both electrons and ions over 69°–75° geomagnetic latitude until the X‐ray flux decreased below the level of X‐class flares. However, the temperature was not enhanced after the previous X2.2 flare in the prenoon sector. (2) At around 75° geomagnetic latitude, the prenoon ion upflow flux slightly increased the day after the X9.3 flare, which is also after the first ICME and a SEP event, while no outstanding enhancement was found at the time of these X flares. (3) The upflow velocity sometimes decreased when the interplanetary magnetic field (IMF) turned southward. (4) Before the first ICME arrival after the SEP event under weak IMF with Bz ~0 nT, a substorm‐like expansion of the auroral arc signature took place without local geomagnetic signature near local midnight, while no notable change was observed after the ICME arrival. (5) AL reached <−2,000 nT only after the arrival of the second ICME with strongly southward IMF. Causality connections between the solar/solar wind event and the ionospheric responses remain unclear.
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| 5. |
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| 6. |
- Bergman, Eva, et al.
(författare)
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Synthesis of theoretical and empirical experineces from nutrient and cyprinid reductions in Lake Ringsjön
- 1999
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Ingår i: Hydrobiologia. - 0018-8158. ; 404, s. 145-156
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Tidskriftsartikel (refereegranskat)abstract
- The reduction in external phosphorus load to Lake Ringsjön during the 1980s, did not result in improved water transparency during the following ten-year period. Furthermore, a fish-kill in the Eastern Basin of the lake, in addition to a cyprinid reduction programme (biomanipulation; 1988–1992), in contrast to theory, did not lead to any increase in zooplankton biomass or size. This absence of response in the pelagic food chain may have been attributed to the increase in abundance of YOY (0+) fish, following the fish reduction programme. Despite the lack of effect on zooplankton, there was a decrease in phytoplankton biomass, a change in species composition and an increase in water transparency following biomanipulation. In 1989, one year after the fish-kill in Eastern Basin, the Secchi depth (summer mean) increased from 60 cm to 110 cm. In the following years, water transparency increased further, despite an increase in phosphorus loading. An unexpected effect of the biomanipulation was an increase in benthic invertebrate and staging waterfowl abundances, which occurred 2–4 years after fish reduction. Hence, the response in the benthic community following biomanipulation was considerably stronger than in the pelagic community. A likely explanation is that reduction in abundance of the benthic feeding fish species bream (Abramis brama), strongly affected the benthic invertebrate fauna. In this paper, we present what we believe happened in Lake Ringsjön, and which processes are likely to have been important at various stages of the restoration process.
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| 7. |
- Gaillard, Marie-Jose, et al.
(författare)
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A late Holocene record of land-use history, soil erosion, lake trophy and lake-level fluctuations at Bjäresjösjön (South Sweden) changes in southern Sweden
- 1991
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Ingår i: Journal of Paleolimnology. - 0921-2728 .- 1573-0417. ; 6, s. 51-81
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Tidskriftsartikel (refereegranskat)abstract
- Land-use history, soil ersosion, lake trophy and lake-level fluctuations during the last 3000 years werereconstructed through a multidisciplinary palaeolimnological study (pollen, plant macrofossils, diatoms,physical and chemical analysis, magnetic measurements and radiometric methods) of a small eutrophiclake in southern Sweden (Bj~resjOsjOn, Scania). There are striking responses in diatom, chemical,sediment yield and magnetic records to land-use changes documented by pollen analysis or historicalsources, and to lake-level changes identified from sedimentary changes. Our multidisciplinary approachassists interpretation of the processes controlling long-term changes and separation of the effects ofdifferent factors (land-use changes, lake-level fluctuations) on individual biostratigraphical records.Climate has controlled processes in the lake indirectly, through lake-level fluctuations, from the LateBronze Age to the Viking Age (700 BC-AD 800). Since the Viking Age, land-use controlled most of thechanges observed in the lake's development and soil erosion processes. Major changes in lake developmentoccurred during the last 200 years, due to a drastic increase in soil erosion and water eutrophicationduring a period of agricultural modernization.
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| 8. |
- Gaillard, Marie-Jose, et al.
(författare)
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A multidisciplinary study of Lake Bjäresjö (S Sweden): land-use history, soil erosion, lake trophy and lake-level fluctuations during the last 3000 years
- 1991
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Ingår i: Hydrobiologia. - 0018-8158 .- 1573-5117. ; 214, s. 107-114
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Tidskriftsartikel (refereegranskat)abstract
- The lake Bjaresjosjon, Southern Scania, Southern Sweden, was studied in the context of the project 'The cultural landscape of the past 6000 years in Southern Sweden'. Pollen, plant macrofossils, diatoms, physical and chemical analysis, magnetic measurements and radiometric methods (Pb-210, C-14) have been used to study palaeoecological changes, i.e. climate, land use, lake trophy and soil erosion during the past 3000 years. This multidisciplinary study shows striking responses of diatom communities, physical and chemical characteristics, sediment yields and magnetic parameters to land-use changes and lake-level fluctuations. Moreover, the latter are closely related to the settlement history at the site, inferred from archaeological records and historical sources. Before 650 AD, the limnological development was affected mainly by lake-level fluctuations, but partly also by human impact (extensive forest clearings and dominant pastoral farming). With the expansion of arable farming (around 650 AD), human impact on the landscape was the major factor influencing soil erosion processes in the catchment and limnological changes in the lake.
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| 9. |
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| 10. |
- Matsson, Hans, et al.
(författare)
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Alpha-cardiac actin mutations produce atrial septal defects.
- 2008
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Ingår i: Human molecular genetics. - : Oxford University Press (OUP). - 1460-2083 .- 0964-6906. ; 17:2, s. 256-65
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Tidskriftsartikel (refereegranskat)abstract
- Atrial septal defect (ASD) is one of the most frequent congenital heart defects (CHDs) with a variable phenotypic effect depending on the size of the septal shunt. We identified two pedigrees comprising 20 members segregating isolated autosomal dominant secundum ASD. By genetic mapping, we identified the gene-encoding alpha-cardiac actin (ACTC1), which is essential for cardiac contraction, as the likely candidate. A mutation screen of the coding regions of ACTC1 revealed a founder mutation predicting an M123V substitution in affected individuals of both pedigrees. Functional analysis of ACTC1 with an M123V substitution shows a reduced affinity for myosin, but with retained actomyosin motor properties. We also screened 408 sporadic patients with CHDs and identified a case with ASD and a 17-bp deletion in ACTC1 predicting a non-functional protein. Morpholino (MO) knockdown of ACTC1 in chick embryos produces delayed looping and reduced atrial septa, supporting a developmental role for this protein. The combined results indicate, for the first time, that ACTC1 mutations or reduced ACTC1 levels may lead to ASD without signs of cardiomyopathy.
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