| 1. |
- Wikgren, Mikael, 1981-, et al.
(författare)
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APOE ε4 is associated with longer telomeres, and longer telomeres among ε4 carriers predicts worse episodic memory
- 2012
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Ingår i: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 33:2, s. 335-344
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Tidskriftsartikel (refereegranskat)abstract
- Both leukocyte telomere length and the apolipoprotein ε4 allele have been associated with mortality, cardiovascular disease, cognition, and dementia. The authors investigated whether leukocyte telomere length was associated with APOE genotype or cognitive abilities in the context of APOE genotype. The setting for this cross-sectional study was 427 nondemented individuals aged 41–81 yr. The authors found that ε4 carriers overall exhibited significantly longer telomeres compared with non-carriers (difference of 268 bp, p = 0.001). This difference was greatest at the lower limit of the age span and nonsignificant at the upper limit, which translated into a significantly higher telomere attrition rate (p = 0.049) among ε4 carriers (37 bp/years) compared with non-carriers (21 bp/year). Further, longer telomeres among ε4 carriers significantly predicted worse performance on episodic memory tasks. No significant associations were found on tasks tapping semantic and visuospatial ability, or among ε3/ε3 carriers. In conclusion, APOE ε4 carriers had longer telomeres compared with non-carriers, but higher rate of attrition. Among them, longer telomeres predicted worse performance on episodic memory tasks. These observations suggest that the ε4 allele is associated with abnormal cell turnover of functional and possibly clinical significance.
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| 2. |
- Wikgren, Mikael, et al.
(författare)
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Longer Leukocyte Telomere Length Is Associated with Smaller Hippocampal Volume among Non-Demented APOE epsilon 3/epsilon 3 Subjects
- 2012
-
Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Telomere length shortens with cellular division, and leukocyte telomere length is used as a marker for systemic telomere length. The hippocampus hosts adult neurogenesis and is an important structure for episodic memory, and carriers of the apolipoprotein E epsilon 4 allele exhibit higher hippocampal atrophy rates and differing telomere dynamics compared with non-carriers. The authors investigated whether leukocyte telomere length was associated with hippocampal volume in 57 cognitively intact subjects (29 epsilon 3/epsilon 3 carriers; 28 epsilon 4 carriers) aged 49-79 yr. Leukocyte telomere length correlated inversely with left (r(s) = -0.465; p = 0.011), right (r(s) = -0.414; p = 0.025), and total hippocampus volume (r(s) = -0.519; p = 0.004) among APOE epsilon 3/epsilon 3 carriers, but not among epsilon 4 carriers. However, the epsilon 4 carriers fit with the general correlation pattern exhibited by the epsilon 3/epsilon 3 carriers, as epsilon 4 carriers on average had longer telomeres and smaller hippocampi compared with epsilon 3/epsilon 3 carriers. The relationship observed can be interpreted as long telomeres representing a history of relatively low cellular proliferation, reflected in smaller hippocampal volumes. The results support the potential of leukocyte telomere length being used as a biomarker for tapping functional and structural processes of the aging brain.
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| 3. |
- Wikgren, Mikael, 1981-, et al.
(författare)
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Short Telomeres in Depression and the General Population Are Associated with a Hypocortisolemic State
- 2012
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Ingår i: Biological Psychiatry. - New York : Elsevier. - 0006-3223 .- 1873-2402. ; 71:4, s. 294-300
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Tidskriftsartikel (refereegranskat)abstract
- Background The hypothalamic-pituitary-adrenal (HPA) axis plays a central role in stress regulation, and leukocyte telomere length (TL) has been suggested to represent a cumulative measure of stress. Depression is intimately related with stress and frequently exhibits a dysregulated HPA axis. We aimed to study the relationships between TL and biological and psychological facets of stress in recurrent major depressive disorder and controls. Methods Leukocyte TL was measured in 91 subjects with recurrent major depressive disorder and 451 control subjects. Stress was assessed from both a biological perspective, by assessing HPA axis function with a weight-adjusted very-low-dose dexamethasone suppression test (DST), and a psychological perspective, with self-report questionnaires. Results TL was shorter among patients compared with control subjects (277 base pairs, p = .001). Overall, short TL was associated with a hypocortisolemic state (low post-DST cortisol and high percentage of cortisol reduction after the DST) among both patients and control subjects but more pronounced among patients. This state, which was overrepresented among patients, was characterized by high familial loading of affective disorders among patients (p = .001) and high C-reactive protein levels among control subjects (p = .040). TL was also inversely associated with stress measured with the Perceived Stress Questionnaire (rs = −.258, p = .003). Conclusions Short TL is associated with depression and hypocortisolism. Because hypocortisolism has been shown to develop from chronic stress exposure, our findings corroborate the concept of TL as a cumulative measure of stress and provide novel insights into the detrimental role of stress in depressive illness and the general population.
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| 4. |
- Wikgren, Mikael, 1981-, et al.
(författare)
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Shorter telomere length is linked to brain atrophy and white matter hyperintensities
- 2014
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Ingår i: Age and Ageing. - : Oxford University Press (OUP). - 0002-0729 .- 1468-2834. ; 43:2, s. 212-217
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Tidskriftsartikel (refereegranskat)abstract
- Background: leukocyte telomere length (TL) is considered a marker of biological aging. Several studies have investigated the link between leukocyte TL and aging-associated functional attributes of the brain, but no prior study has investigated whether TL can be linked to brain atrophy and white matter hyperintensities (WMHs); two prominent structural manifestations of brain aging. Methods: we investigated whether leukocyte TL was related to brain atrophy and WMHs in a sample of 102 non-demented individuals aged 64-75 years. Results: shorter TL was related to greater degree of subcortical atrophy (beta = -0.217, P = 0.034), but not to cortical atrophy. Furthermore, TL was 371 bp shorter (P = 0.041) in participants exhibiting subcortical WMHs, and 552 bp shorter (P = 0.009) in older participants exhibiting periventricular WMHs. Conclusion: this study provides the first evidence of leukocyte TL being associated with cerebral subcortical atrophy and WMHs, lending further support to the concept of TL as a marker of biological aging, and in particular that of the aging brain.
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| 5. |
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| 6. |
- Åberg-Bengtsson, Lisbeth, et al.
(författare)
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När Agnes fick va solen så fattade man ju precis : Om illustrationer i undervisning av yngre elever
- 2014
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Ingår i: Resultatdialog. - Stockholm : Vetenskapsrådet. - 9789173072472 ; , s. 246-254
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Att göra adekvata tolkningar av bilder och modeller kan vara verkliga stötestenar för många barn. Särskilt besvärligt förefaller det vara att tolka bilder av processer och förlopp i tryckta läromedel. Även enk-lare bilder och vanliga symboler kan dock leda till icke avsedda tolkningar. Barnen i studien föreföll i många fall betrakta illustrationerna som enbart dekoration och förbigick dem ofta om de inte direkt uppmärksammades på dem. Å andra sidan kunde illustrationer också, särskilt sådana som visade på extremer av något slag, väcka förundran och intresse.
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| 7. |
- Adman, Per, et al.
(författare)
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171 forskare: ”Vi vuxna bör också klimatprotestera”
- 2019
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Ingår i: Dagens nyheter (DN debatt). - Stockholm. - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- DN DEBATT 26/9. Vuxna bör följa uppmaningen från ungdomarna i Fridays for future-rörelsen och protestera eftersom det politiska ledarskapet är otillräckligt. Omfattande och långvariga påtryckningar från hela samhället behövs för att få de politiskt ansvariga att utöva det ledarskap som klimatkrisen kräver, skriver 171 forskare i samhällsvetenskap och humaniora.
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| 8. |
- Breimer, Michael, 1951, et al.
(författare)
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Glycosphingolipid composition of epithelial cells isolated along the villus axis of small intestine of a single human individual
- 2012
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Ingår i: Glycobiology. - : Oxford University Press (OUP). - 1460-2423 .- 0959-6658. ; 22:12, s. 1721-1730
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Tidskriftsartikel (refereegranskat)abstract
- A 6-cm fresh proximal ileum surgical specimen from a blood group A(1)Le(a-b+) secretor individual was used for stepwise isolation of epithelial cells from villus tip to crypt bottom by gentle washing with ethylenediaminetetraacetic acid-containing buffer. Acid and non-acid sphingolipids were prepared from the epithelial cell fractions and the non-epithelial intestinal residue. Molecular information on the sphingolipid composition was obtained without further isolation of individual species by applying thin-layer chromatography using chemical and biological (monoclonal antibodies, cholera toxin, Escherichia coli) detection reagents, mass spectrometry and proton NMR spectroscopy of derivatized glycolipids. In this way, the structure of major and minor saccharides, ceramide components and their relative amounts were obtained. Epithelial cells and non-epithelial residue were distinctly different in their sphingolipid composition. Sphingomyelin was the major single component in both compartments. Characteristic for epithelial cells was the dominance of monoglycosylceramides, sulphatides and blood group fucolipids (mainly Le(b) hexaglycosylceramides and ALe(b) heptaglycosylceramides). The non-epithelial residue had about five times less glycolipids mainly mono-, di-, tri- and tetra-glycosylceramides and gangliosides, including the GM1 ganglioside. The ceramides were more hydroxylated (1-2 additional hydroxyls) in epithelial cell glycolipids compared with the non-epithelial residue. Combined with a separate detailed study on the glycoproteins of the same epithelial cell preparation, this human intestinal sample is the only epithelial cell preparation where both protein- and lipid-linked saccharides are characterized in detail.
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| 9. |
- Davidsson, Eva, et al.
(författare)
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Trender och likvärdighet : Svenska elevers resultat på PISA naturvetenskap i en internationell jämförelse
- 2013
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Ingår i: Utbildning och Demokrati. - : Örebro Universitet. - 1102-6472 .- 2001-7316. ; 22:3, s. 37-52
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Tidskriftsartikel (refereegranskat)abstract
- Sweden experiences an evident downward trend regarding Swedish students’ performances on large-scale science tests during the last 15 years. This article aims to analyze this trend using percentiles, analyze the trend of in-between school variance but also to compare the Swedish results to other Nordic countries as well as to some countries that have experienced a significant upward or downward trend during this period. The analyses reveal that the downward trend could be ascribed to the descending results of low- and mid-performers. Furthermore it shows an increasing in-between school variance in Sweden as well as in other countries experiencing downward performances. It is possible to conclude that weaker results from low-performers are closely related to an increased in-between school variance and thereby decreased equity.
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| 10. |
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| 11. |
- Eliasson, Nina, 1965-
(författare)
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Att kommunicera skolans naturvetenskap : ett genusperspektiv på elevers deltagande i gemensam och enskild kommunikation
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Both individual and whole class communication of students are described in this thesis, which is based on a clear gender perspective. Two articles describe the participation of boys and girls in communication with the whole class, the empirical data collected consisting of videotaped lessons. The extent to which boys and girls participate in the communication is reported in the first study, and in the second the extent to which boys and girls respond to the teacher's closed or open questions about science is presented. The third study reports boys' and girls' individual communication when responding to written science questions. The summary chapter ties the results together from the perspective of Positioning Theory, making the thesis a result of Mixed Methods Research.Results show that boys participate in whole class communication more often than girls, with approximately the same level of dominance as shown in research from the early 80s. Boys also answer more questions than girls, the differences becoming apparent when teachers ask closed questions that can be answered in one or two words. In isolation, girls answer written questions to the same extent as boys, but give longer responses containing a more developed scientific language.Results showing that boys position themselves as knowledgeable more often than girls when teachers ask closed questions, are explained from the perspective of Positioning Theory. Girls more often position themselves as knowledgeable when teachers ask open questions that require reflection. In test situations, with time for reflection, the boys and girls position themselves as knowledgeable students to the same extent.Teachers need to be aware of the positioning attempts created by teaching, and consequently take into account that different approaches in teaching provide boys and girls with different access to the communication space.
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| 12. |
- Eliasson, Nina, 1965-, et al.
(författare)
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Boys' and Girls' written responses to PISA science questions
- 2017
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Ingår i: NorDiNa. - : University of Oslo Library. - 1504-4556 .- 1894-1257. ; 13:2, s. 149-162
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Tidskriftsartikel (refereegranskat)abstract
- For the first time student responses to science questions from the Swedish PISA 2006 Main Study and the PISA 2015 Field Trial have been used in order to investigate differences in boys’ and girls’ written responses. Students’ correct and incorrect answers to the science questions are studied with respect to response length, the number of everyday words used, and the inclusion of nouns and long words in the responses. The results reveal that girls give longer and denser correct responses to most of the questions, compared to boys. The difference in response length cannot be explained by girls’ excessive use of the most common Swedish words, since boys and girls use the same proportion of these words. For incorrect answers the only difference between boys and girls is in the response length, since girls give longer answers than boys.
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| 13. |
- Eliasson, Nina, 1965-, et al.
(författare)
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PISA 2012 - Digital problemlösningsförmåga hos 15-åringar i ett internationellt perspektiv
- 2014
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I PISA 2012 genomfördes för första gången ett digitalt prov i problemlösning, i vilket ca 1250 svenska 15-åringar från 209 skolor deltog. Problemlösning kräver bland annat nyfikenhet, uthållighet och kritiskt tänkande. Att kunna lösa problem är också en av de förmågor som på senare tid alltmer har uppmärksammats som betydelsefulla för framgång i utbildning och arbetsliv. Det digitala problemlösningsprovet genomfördes av 28 OECD-länder och 16 icke OECD-länder.
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| 14. |
- Eliasson, Nina, et al.
(författare)
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Teacher-Student Interaction in Contemporary Science Classrooms : Is Participation Still a Question of Gender?
- 2016
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Ingår i: International Journal of Science Education. - : Informa UK Limited. - 0950-0693 .- 1464-5289. ; 38:10, s. 1655-1672
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Tidskriftsartikel (refereegranskat)abstract
- We show that boys still have a greater access to the space for interaction in science classrooms, which is unexpected since in Sweden today girls perform better in these subjects than boys. Results from video-recorded verbal communication, referred to here as interaction, show that the distribution of teacher–student interaction in the final year of lower secondary school follows the same patterns as in the 1980s. The interaction space for all kinds of talk continues to be distributed according to the two-thirds rule for communication in science classrooms as described by previous research. We also show that the overall interaction space in science classrooms has increased for both boys and girls when talk about science alone is considered. Another finding which follows old patterns is that male teachers still address boys more often than girls. This holds true both for general talk and for talk about science. If a more even distribution of teacher–student interaction is desirable, these results once again need to be considered. More research needs to be undertaken before the association between girls’ attitudes and interest in science in terms of future career choice and the opportunity to participate in teacher–student interaction is more clearly understood.
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| 15. |
- Eliasson, Nina, et al.
(författare)
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The role of questions in the science classroom : how girls and boys respond to teachers' questions
- 2017
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Ingår i: International Journal of Science Education. - : Informa UK Limited. - 0950-0693 .- 1464-5289. ; 39:4, s. 433-452
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study was to explore (a) to what extent male and female science teachers pose different types of questions and (b) if the type of science question posed influences the extent to which boys or girls respond to them. Transcripts of the teacher–student interaction in a whole-class situation were analysed, with attention paid to interactions that involved science questions. Closed and open questions were used. Results revealed that the percentage of closed questions posed corresponded to 87%. Results show that teachers mainly use closed questions, and responses from boys to closed questions are in the majority regardless of if the question is posed by a female teacher (56%) or a male teacher (64%). Both categories of closed questions are mainly considered lower order questions that do not facilitate higher cognitive levels in students. Thus, a direct consequence of an excessive use of this type of questions may be that both boys and girls will be given less opportunities to practise their ability to talk about science. Less access to general classroom interaction may also affect girls’ attitudes to science in a negative way which could ultimately hamper the recruitment of girls to higher scientific studies.
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| 16. |
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| 17. |
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| 18. |
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| 19. |
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| 20. |
- Fredriksson, Ulf, 1954-, et al.
(författare)
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PISA - och sedan?
- 2018
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Ingår i: PISA under 15 år – resultat och trender. - Stockholm : Natur och kultur. - 9789127819818 ; , s. 199-205
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 21. |
- Fredriksson, Ulf, et al.
(författare)
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PISA under 15 år – resultat och trender
- 2018
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- I den unika boken PISA under 15 år ger de forskare som arbetat med undersökningen i Sverige sin bild av vad som hänt under de femton år som gått sedan den första undersökningen genomfördes. Här beskrivs bland annat:Bakgrunden till undersökningen, hur den har utvecklats och genomförts.Resultaten från samtliga sex undersökningar, ur både ett nationellt och internationellt perspektiv.Skillnader i resultat utifrån likvärdighet, genus och utländsk bakgrund i olika tvärstudier som utgått från PISA-undersökningen.Författarna diskuterar genomgående vad vi kan lära oss av PISA och tar även upp den kritik som riktats mot undersökningen. Avslutningsvis lyfts hur framtiden för PISA kan komma att se ut.
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| 22. |
- Fredriksson, Ulf, 1954-, et al.
(författare)
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Svenska resultat i internationell jämförelse
- 2018
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Ingår i: PISA under 15 år – resultat och trender. - Stockholm : Natur och kultur. - 9789127819818 ; , s. 161-169
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 23. |
- Fredriksson, Ulf, 1954-, et al.
(författare)
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Vad kan vi lära av PISA?
- 2018
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Ingår i: PISA under 15 år – resultat och trender. - Stockholm : Natur och kultur. - 9789127819818 ; , s. 170-177
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 24. |
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| 25. |
- Haataja, Sauli, et al.
(författare)
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Oligosaccharide-receptor interaction of the Galα1-4Gal binding adhesin of Streptococcus suis : Combining site architecture and characterization of two variant adhesin specificities
- 1994
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Ingår i: Journal of Biological Chemistry. - 0021-9258. ; 269:44, s. 27466-27472
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Tidskriftsartikel (refereegranskat)abstract
- The sugar binding specificities of two groups of Streptococcus suis, a pig pathogen that causes meningitis also in man, were determined. Both the group represented by a recently characterized strain inhibitable by galactose and N-acetylgalactosamine (type PN) and the group inhibitable by galactose (type PO) were found by hemagglutination and solid-phase binding inhibition experiments to recognize the disaccharide Galα1-4Gal of the P1 and Pk blood group antigens. Both types preferred the disaccharide in terminal position. PN showed some, whereas PO showed almost no, binding to the globoside oligosaccharide containing an additional GalNAcβ1-3 residue. The complete hydrogen bonding patterns were determined by using deoxy and other synthetic derivatives of the receptor disaccharide, and the constructed models of the interactions were compared with that of Escherichia coli PapG396 adhesin. The essential hydroxyls for binding were the HO-4', HO- 6', HO-2, and HO-3 hydroxyls on the β'α-side of the Galα1-4Gal molecule. Type PO adhesin also formed weak interactions with the hydroxyls HO-6 and HO-3'. The mechanism differed from that of E. coli, which binds to a cluster of five hydroxyls (HO-6, HO-2', HO-3', HO-4', and HO-6') and thus to a different part of the receptor disaccharide. These results represent the first example of the comparison of the saccharide receptor hydrogen bonding patterns of two bacterial organisms of different origin and show that the same saccharide may be recognized by two different binding mechanisms.
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| 26. |
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| 27. |
- Hedfors, Jim, et al.
(författare)
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Clouds and Be-7: Perusing connections between cosmic rays and climate
- 2006
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 111:D2, s. D02208-
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Tidskriftsartikel (refereegranskat)abstract
- [1] Time series data on Be-7, precipitation, temperature, and satellite imagery of cloud cover over Scandinavia, together with cosmic ray and sunspot activity, were used to elucidate the relationship between cosmic rays and clouds, and ultimately climate change. The results indicate a coherent negative correlation between total cloud cover and Be-7 on intraseasonal, seasonal, and decadal scales. Although the reasons behind this correlation are unclear, a full-scale implication of this feature is in the possible use of Be-7 and Be-10 records for proxy paleo-reconstruction of total cloud cover. This is a strongly needed, but generally difficult to quantify parameter in climate models.
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| 28. |
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| 29. |
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| 30. |
- Jakobsson, Anders, et al.
(författare)
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Exploring Epistemological Trends in Students’ Understanding of Science from the Perspective of Large-Scale Studies
- 2013
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Ingår i: ISRN Education. - : Hindawi Publishing Corporation. - 2090-8644 .- 2090-8652. ; 2013:196014
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Tidskriftsartikel (refereegranskat)abstract
- This paper highlights howresults fromlarge-scale studies can be used to understand students’ knowledge of science. Several scholars express critique of today’s PISA framework, especially with regard to the presentation of the results as national rankings, and suggest alternative and complementary methods.The present study has used PISA data to reveal hidden patterns in the results. The results show a general descending trend in items focusing on the nature of science and how new scientific knowledge is generated. On the other hand, there is an obvious upward trend regarding tasks that measure fact-based elementary or root knowledge.These trends are slightly differentiated at a national level, as the time and magnitude of the decline or increase may vary.
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| 31. |
- Jidesjö, Anders, et al.
(författare)
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Science for all or science for some: What Swedish students want to learn about in secondary science and technology and their opinions on science lessons
- 2009
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Ingår i: NorDiNa. - : UiO, University of Oslo. - 1504-4556 .- 1894-1257. ; 5:2, s. 213-229
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Tidskriftsartikel (refereegranskat)abstract
- This article presents Swedish results from ‘the Relevance of Science Education’ (ROSE) study, which is a large world wide comparative research project based at the University of Oslo. The Swedish sample consisted of 751 students, most of whom were 15 years old, from 29 schools and data were collected in spring 2003. Student opinions about science lessons are presented in relation to enrolment intentions for upper secondary school together with what they want to learn about in science and technology. The findings indicate that secondary science instruction seems to address only a minority of the students, those that have chosen science or technology in their further education. At the same time, all students have interest in science and technology and many seem most interested in some important issues in societal development. The results are discussed from the perspective of learners and contribute to the debate about establishing a scientific literacy approach in compulsory education.
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| 32. |
- Karlsson, Karl-Göran
(författare)
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A 10 year cloud climatology over Scandinavia derived from NOAA advanced very high resolution radiometer imagery
- 2003
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Ingår i: International Journal of Climatology. - : Wiley. - 0899-8418 .- 1097-0088. ; 23:9, s. 1023-1044
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Tidskriftsartikel (refereegranskat)abstract
- Results from a satellite-based method to compile regional cloud climatologies covering the Scandinavian region are presented. Systematic processing of multispectral image data from the NOAA Advanced Very High Resolution Radiometer (AVHRR) instrument has been utilized to provide monthly cloud climatologies covering the period 1991-2000. Considerable local-scale variation of cloud amounts was found in the region. The inland Baltic Sea and adjacent land areas exhibited a large-amplitude annual cycle in cloudiness (high cloud amounts in winter, low cloud amounts in summer) whereas a weak-amplitude reversed annual cycle (high cloud amounts with a weak maximum in summer) was found for the Scandinavian mountain range. As a contrast, conditions over the Norwegian Sea showed high and almost unchanged cloud amounts during the course of the year. Some interesting exceptions to these patterns were also seen locally. The quality of the satellite-derived cloud climatology was examined through comparisons with climatologies derived from surface cloud observations, from the International Satellite Cloud Climatology Project (ISCCP) and from the European Centre for Medium-range Weather Forecasts ERA-40 data set. In general, cloud amount deviations from surface observations were smaller than 10% except for some individual winter months, when the separability between clouds and snow-covered cold land surfaces is often poor. The ISCCP data set showed a weaker annual cycle in cloudiness, generally caused by higher summer-time cloud amounts in the region. Very good agreement was found with the ERA-40 data set, especially for the summer season. However, ERA-40 showed higher cloud amounts than SCANDIA and ISCCP during the winter season. The derived cloud climatology is affected by errors due to temporal AVHRR sensor degradation, but they appear to be small for this particular study. The data set is proposed as a valuable data set for validation of cloud description in numerical weather prediction and regional climate simulation models.
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| 33. |
- Karlsson, Karl-Göran
(författare)
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Cloud climate investigations in the Nordic region using NOAA AVHRR data
- 1997
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Ingår i: Theoretical and Applied Climatology. - 0177-798X. ; 57:3-4, s. 181-195
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Tidskriftsartikel (refereegranskat)abstract
- A method to estimate monthly cloud conditions (monthly cloud frequencies) from multispectral satellite imagery is described. The operational cloud classification scheme SCANDIA (the SMHI Cloud ANalysis model using DIgital AVHRR data), based on high resolution imagery from the polar orbiting NOAA-satellites, has been used to produce monthly cloud frequencies for the entire year of 1993 and some additional months in 1991, 1992, 1994 and 1995. Cloud analyses were made for an area covering the Nordic countries with a horizontal resolution of four km. Examples of seasonal, monthly and diurnal variation in cloud conditions are given and an annual mean for 1993 is presented. Comparisons with existing surface observations showed very good agreement for horizontal cloud distributions but approximately 5% smaller cloud amounts were found in the satellite estimations. The most evident problems were encountered in the winter season due to difficulties in identifying low-level cloudiness at very low sun elevations. The underestimation in the summer season was partly fictious and caused by the overestimation of convective cloud cover by surface observers. SCANDIA results were compared to ISCCP (International Satellite Cloud Climatology Project) cloud climatologies for two selected months in 1991 and 1992. ISCCP cloudiness was indicated to be higher, especially during the month with anticyclonic conditions where a cloudiness excess of more than 10% were found. The regional variation of cloud conditions in the area was found to be inadequately described by ISCCP cloud climatologies. An improvement of the horizontal resolution of ISCCP data seems necessary to enable use for regional applications. The SCANDIA model is proposed as a valuable tool for local and regional monitoring of the cloud climatology at high latitudes. More extensive comparisons with ISCCP cloud climatologies are suggested as well as comparisons with modelled cloudiness from atmospheric general circulation models and climate models. Special studies of cloud conditions in the Polar areas are also proposed.
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| 34. |
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| 35. |
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| 36. |
- Karlsson, Karl Göran, et al.
(författare)
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Fysik i ingenjörsutbildningen
- 2002
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Ingår i: Sju ämnesdidaktiska artiklar. - Härnösand : Institutionen för humaniora, Mitthögskolan. - 9163126680 ; , s. 33-50
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Den obligatoriska fempoängskursen i fysik som ingår i Mitthögskolans ingenjörsutbildningar uppfattas som svår. Vi har undersökt kursen som genomfördes våren 2001 i Härnösand och Sundsvall. Efter två tentamina är knappt hälften av studenterna godkända. Låg studiemotivation, som dessutom minskar under kursens gång, i kombination med begränsade arbetsinsatser tycks förklara en stor del av det dåliga resultatet. Den bristande motivationen kan förklaras av att studenterna inte uppfattar innehållet som nyttigt varken för de vidare studierna eller för sitt kommande yrkesliv.
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| 37. |
- Karlsson, Karl Göran, 1948-, et al.
(författare)
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Likvärdighet
- 2018
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Ingår i: Pisa under 15 år. - Stockholm : Natur och kultur. - 9789127819818 ; , s. 115-130
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 38. |
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| 39. |
- Karlsson, Karl-Göran, 1948-, et al.
(författare)
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Läsande och naturvetenskap - några resultat från den svenska PISA-undersökningen
- 2004
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Ingår i: Naturfagenes didaktikk - en disiplin i forandring?. - Kristiansand : Høyskoleforlaget i samarbeid med Høgskolen i Agder. - 8276345689 ; , s. 51-63
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Konferensbidrag (refereegranskat)abstract
- I denna studie har vi, för ett urval av PISA-uppgifter, detaljstuderat hög- respektive lågpresterande elever för att försöka förstå vilka faktorer som är avgörande för resultaten inom den naturvetenskapliga delen av PISA-undersökningen. Läsförståelse tycks vara av avgörande betydelse för elevernas resultat inom naturvetenskap. I synnerhet gäller detta för de uppgifter där eleverna ska formulera egna svar.
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| 40. |
- Karlsson, Karl Göran, 1948-, et al.
(författare)
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Naturvetenskap i PISA
- 2018
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Ingår i: Pisa under 15 år. - Stockholm : Natur och kultur. - 9789127819818 ; , s. 86-103
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 41. |
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| 42. |
- Karlsson, Karl Göran, et al.
(författare)
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Scientific Literacy and Educational Reforms in Norway and Sweden
- 2006
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Ingår i: Northern Lights on PISA 2003. - 9289313005 ; , s. 267-
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- In December 2004, when results from PISA 2003 were presented, much focus in media was on ranking lists and overall changes since PISA 2000. In Sweden no significant changes between 2000 and 2003 occurred in none of the three test domains in PISA (reading literacy, mathematical literacy and scientific literacy). Moreover, Swedish scores were significantly above the OECD average in all three domains. In Norway results in reading and mathematics showed no significant changes but a considerable drop in science results. The Norwegian science score was also below the OECD average, whereas reading and mathematics scores were close to the international means (OECD 2001, 2004). In this article we will take a closer look at the PISA science results for the two countries in order to discuss some possible links to educational reforms that has been introduced during the last decennium. For that purpose we will also discuss some results from TIMSS (Trends in International Mathematics and Science Study), or more precisely: results for the science grade 8 part of the study. In addition to the national PISA 2003 reports for Sweden (Skolverket 2004c) and Norway (Kjærnsli et al 2004), also the national TIMSS 2003 reports (Skolverket 2004a, Grønmo et al 2004) discuss the achievement drop in science. In addition, Kjærnsli et al (2005) has recently focused quite specifically on the general drop of competencies in the Nordic countries during the last decennium.
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| 43. |
- Karlsson, Karl-Göran, 1959-
(författare)
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The use of a satellite-derived cloud climatology for studying cloud-aerosol processes and the performance of regional cloud climate simulations
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The entry of satellite-derived decadal cloud datasets with homogeneous coverage in time and space enables studies not possible before. This thesis presents two such applications. The first study deals with cloud-aerosol processes and the second with an evaluation of cloud simulations from a regional climate model.The first part of the thesis describes the used satellite-derived dataset based on imagery from the Advanced Very High Resolution Radiometer (AVHRR) on the polar orbiting NOAA satellites. A method for cloud retrieval and the compilation of a 1991-2000 Scandinavian cloud climatology are described.The second part reveals an intriguing anti-correlation between monthly mean satellite-derived cloudiness and the concentration of the cosmogenetic isotope Beryllium-7 in near-surface aerosol samples for three measurement sites in Sweden. Large-scale transport processes are suggested as the most likely physical mechanism for this behaviour but more complex relations to cloud microphysical processes are not ruled out.The final part presents a thorough evaluation of cloud simulations of the SMHI Rossby Centre regional atmospheric model (RCA3). Several model-to-satellite adaptations are applied to avoid artificial biases of results. The study stresses the necessity to account for initial differences between observed and modelled clouds caused by satellite cloud detection limitations. Results show good agreement of modelled and observed cloud amounts while the vertical distribution of clouds appears largely different. RCA3 underestimates medium-level clouds while overestimating low- and high-level clouds. Also, the current use of the Maximum cloud overlap approach in the radiation scheme and an indicated excess of cloud condensate in modelled clouds appear to create excessive cloud optical thicknesses with serious implications for the surface radiation budget.Future applications are outlined based on greatly enhanced satellite-derived cloud and radiation budget datasets.
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| 44. |
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| 45. |
- Karlsson, Lena, 1964, et al.
(författare)
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Risk of Recurrent Stroke in Patients with Symptomatic Mild (20-49% NASCET) Carotid Artery Stenosis
- 2016
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Ingår i: European Journal of Vascular and Endovascular Surgery. - : Elsevier BV. - 1078-5884. ; 52:3, s. 287-294
-
Tidskriftsartikel (refereegranskat)abstract
- Objective: The objective of this study was to evaluate the risk of recurrent ischaemic stroke in patients with ultrasound assessed symptomatic mild carotid artery stenosis (20-49% NASCET) treated solely with modern medical treatment. Method: This was a retrospective, observational register cohort study. Three groups of patients were recruited from a database of all carotid Doppler ultrasound examinations performed in the Gothenburg region between 2004 and 2009. Patients with symptomatic mild carotid artery stenosis (n = 162) were compared with patients with asymptomatic carotid artery stenosis (n = 301) of equal degree and a group of patients with surgically (CEA) treated symptomatic moderate or severe carotid artery stenosis (n = 220). Kaplan-Meier estimates and Cox proportional hazard models were used to compare the primary outcome (ipsilateral ischaemic stroke) between groups. Results: After a 3 year follow up, the cumulative incidence of recurrent ipsilateral stroke in patients with symptomatic mild carotid artery stenosis was 7.4%. Patients with symptomatic mild carotid artery stenosis had a substantially increased risk of recurrent ipsilateral stroke compared with asymptomatic patients with equal degree of stenosis (HR 5.5. 95% CI 1.8-17.1; p = .003) as also compared with patients with CEA treated symptomatic moderate or severe stenosis (HR 7.8. 95% CI 1.62-37.8; p = .011). Conclusions: The present study on patients with symptomatic mild carotid artery stenosis, as determined by Doppler ultrasound, shows that there is still a substantial risk of recurrent stroke in this group. (C) 2016 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.
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| 46. |
- Kilpeläinen, Tuomas O, et al.
(författare)
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Genome-wide meta-analysis uncovers novel loci influencing circulating leptin levels
- 2016
-
Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 7
-
Tidskriftsartikel (refereegranskat)abstract
- Leptin is an adipocyte-secreted hormone, the circulating levels of which correlate closely with overall adiposity. Although rare mutations in the leptin (LEP) gene are well known to cause leptin deficiency and severe obesity, no common loci regulating circulating leptin levels have been uncovered. Therefore, we performed a genome-wide association study (GWAS) of circulating leptin levels from 32,161 individuals and followed up loci reaching P<10(-6) in 19,979 additional individuals. We identify five loci robustly associated (P<5 × 10(-8)) with leptin levels in/near LEP, SLC32A1, GCKR, CCNL1 and FTO. Although the association of the FTO obesity locus with leptin levels is abolished by adjustment for BMI, associations of the four other loci are independent of adiposity. The GCKR locus was found associated with multiple metabolic traits in previous GWAS and the CCNL1 locus with birth weight. Knockdown experiments in mouse adipose tissue explants show convincing evidence for adipogenin, a regulator of adipocyte differentiation, as the novel causal gene in the SLC32A1 locus influencing leptin levels. Our findings provide novel insights into the regulation of leptin production by adipose tissue and open new avenues for examining the influence of variation in leptin levels on adiposity and metabolic health.
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| 47. |
- Lundgren, Maria, et al.
(författare)
-
Hur PISA-undersökningarna genomförs
- 2018
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Ingår i: Pisa under 15 år. - Stockholm : Natur och kultur. - 9789127819818 ; , s. 25-41
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 48. |
- Olande, Oduor
(författare)
-
Students' narratives from graphical artefacts : Exploring the use of mathematics tools and forms of expression in students' graphicacy
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The research concerns presented in this dissertation addresses aspects of students’ interaction with commonly occurring graphical artefacts in teaching and learning environments. In particular, focus is on how the students make sense of these artefacts in relation to subject specific tools and forms of expression.The dissertation comprises of four studies guided by a semiotics cultural- historical perspective to cognition. The first study which is largely quantitative, analyses the percentage scores from students’ responses to selected items from OECD PISA surveys for items containing graphical elements. The second and the third studies in keeping with a more sociocultural perspective to learning as point of departure, examine the students’ collaborative interaction around tasks containing graphical elements. The fourth study explores the nature of students’ solutions from the Swedish national test in mathematics based on a tools and forms of expression sensitive empirically derived construct of Identification contra Critical-analytical approach to graphicacy.The main outcomes of these studies can be summarised as follows: first there is justification for re-examining the predominant characterisation of students’ interaction with graphical artefacts. Secondly, while it is not uncommon for students to take a more visual-perceptive and intuitive approach to graphicacy, results from task items interactions indicate that a Critical-analytical approach seems to be more reliable and capable of yielding desirable outcomes. The outcomes of these studies call for vigilance on the type of tasks used in relation to graphicacy and how these can be used to foster students’ Critical-analytical disposition.
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| 49. |
- Oscarsson, Magnus, et al.
(författare)
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Health Care or Atom Bombs : Interest profiles in science among 15-year old students in Sweden
- 2011
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Ingår i: NorDiNa. - Oslo. - 1504-4556 .- 1894-1257. ; 7:2, s. 190-201
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Tidskriftsartikel (refereegranskat)abstract
- The ROSE survey explores which science topics 15-year-old students want to study. By carrying out a factor analysis on results from Sweden it was possible to describe ten interest profiles. The interest profile with the strongest connection to the students’ interest in school science consists of topics such as explosive chemicals, ABC weapons, electric shocks, atoms and molecules. Only a minority of the students has these interests, but it is this minority who appreciates school science and who chooses to study science at upper secondary school. The factor analysis also reveals large differences between genders and furthermore, that the students’ own interests govern their choice of study programme at upper secondary school.
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| 50. |
- Oscarsson, Magnus, et al.
(författare)
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Science for all or science for some : What Swedish science students want to learn about in secondary science and technology and their opinions on science lessons.
- 2009
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Ingår i: NorDiNa. - 1504-4556 .- 1894-1257. ; 5:2, s. 213-229
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Tidskriftsartikel (refereegranskat)abstract
- This article presents Swedish results from ‘the Relevance of Science Education’ (ROSE) study, which is a large world wide comparative research project based at the University of Oslo. The Swedish sample consisted of 751 students, most of whom were 15 years old, from 29 schools and data were collected inspring 2003. Student opinions about science lessons are presented in relation to enrolment intentions for upper secondary school together with what they want to learn about in science and technology.The findings indicate that secondary science instruction seems to address only a minority of the students, those that have chosen science or technology in their further education. At the same time, all students have interest in science and technology and many seem most interested in some important issues in societal development. The results are discussed from the perspective of learners and contribute to the debate about establishing a scientific literacy approach in compulsory education.
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