What makes a star turn violent? : exploring high-mass star formation and stellar magnetic helicity

High-mass stars play an important role in both the dynamical and chemical evolution of the galaxy, hence how they form has long been a topic of interest. In this thesis I explore accretion as a possible means of forming high-mass stars. I use a radiation hydrodynamics code to simulate accretion onto a star which emits ionising radiation. Usually accretion is assumed to end once ionisation begins, however I find accretion continues through the ionisation front whilst the ionised region is gravitationally trapped. This extended period of accretion increases the amount of material added to the star. As most high-mass stars are observed in close binary systems, next I develop a semi-analytic model to investigate whether accretion onto wide lowmass binaries can increase the mass of the stars and simultaneously decrease their separation. The result suggests magnetic braking of the accretion flow is a feasible way of forming the most massive close binary systems. The second part of this thesis focuses on the magnetic helicity density of low-mass stars. There has been growing interest in magnetic helicity as a potential tracer of stellar eruptions, but measurements based on observations have been limited to the Sun. I present an analytic expression for the magnetic helicity density across any stellar surface given only observable quantities. This expression is used to calculate the magnetic helicity density of 52 stars, which is then plotted against other stellar parameters. I find mostly different behaviours for the partially and largely convective stars, except when plotting helicity density against toroidal magnetic energy. In that case the entire stellar sample follows the same power law. Comparing the Sun to the other stars I find the variation in solar helicity densities across a solar cycle falls within the scatter of the stellar values."This work was supported by the Carnegie Trust for the Universities of Scotland through a Carnegie PhD Scholarship." -- Fundin

Rusmidler i Norge 2013

Øvrige bidragsytere: Ellen J. Amundsen, Ola Røed Bilgrei, Kristin Buvik, Marit Edland-Gryt, Odd Hordvin, Elisabeth Kvaavik, Grethe Lauritzen, Ingeborg Lund, Marianne Lund, Thomas Anton Sandøy, Janne Scheffels, Øystein Skjælaaen, Gunnar Sæbø og Tord Finne Vedøy. SIRUS' årlige rapport Rusmidler i Norge er for 2013 utvidet med mer omfattende tekst og flere tabeller enn tidligere. Innholdet er også omorganisert og delt inn i kapitlene alkohol, tobakk, avhengighetsskapende legemidler, narkotika, sniffing, doping og tjenestetilbudet. I hvert av substanskapitlene blir det gitt en beskrivelse av de aktuelle stoffene, hvordan de virker, og deres skadepotensial og aktuelle lovreguleringer. Så følger aktuelle registerdata og data fra ulike undersøkelser. Det gis også en historisk oversikt over viktige hendelser og beslutninger i tilknytning til de forskjellige substansområdene og til tjenestetilbudet

Omsorg til personer med demens i et samhandlingsperspektiv

Fordypningsoppgave, videreutdanning eldreomsorg - med vekt på psykisk helse, 201

Criterion validity of a 10-category scale for ranking physical activity in Norwegian women.

BACKGROUND: Accurate measurement of physical activity (PA) is critical to establish dose-response relationships with various health outcomes. We compared the self-administered PA questionnaire from the Norwegian Women and Cancer Study (NOWAC) with a criterion method in middle-aged Norwegian women. METHODS: A sample of 177 randomly recruited healthy women attended two clinical visits approximately 4-6 months apart. At each visit, the women completed the NOWAC PA questionnaire (NOPAQ), rating their overall PA level on a 10-category scale (1 being a "very low" and 10 being a "very high" PA level) and performed an 8-minute step-test to estimate aerobic fitness (VO2max). After each visit, the women wore a combined heart rate and movement sensor for 4 consecutive days of free-living. Measures of PA obtained from the combined heart rate and movement sensor, which were used as criterion, included individually calibrated PA energy expenditure (PAEE), acceleration, and hours/day of moderate-to-vigorous intensity PA (MVPA). These were averaged between visits and compared to NOPAQ scores at visit 2. RESULTS: Intra-class correlation coefficients for objective measures from both free-living periods were in the range of 0.65-0.87 (P < 0.001), compared to 0.62 (P < 0.001) for NOPAQ. There was a moderate but significant (P < 0.001) Spearman's rank correlation coefficient in the range of 0.36-0.46 between NOPAQ and objective measures of PA. Linear trends for the association between the NOPAQ rating scale with PAEE, hours/day of MVPA and VO2max (P < 0.001) were also demonstrated. CONCLUSIONS: Self-reported PA level measured on a 10-category scale appears valid to rank PA in a female Norwegian population.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Physical activity and mortality among Norwegian women – the Norwegian Women and Cancer Study

Physical activity (PA) and its relationship with all-cause mortality suggest a strong and consistent inverse association. This study prospectively investigated the association between PA level and mortality among participants of the Norwegian Women and Cancer (NOWAC) Study. A total of 66,136 NOWAC participants were followed-up until December 31st 2008. PA level and possible confounding factors were obtained through a self-administered questionnaire at enrolment. Cox proportional hazards regression was used to calculate adjusted relative risks (RRs) and 95% confidence intervals (CIs) for all-cause, cardiovascular disease (CVD) and cancer mortality and PA levels defined from 1 to 10 on a global scale. PA levels 1–4 were associated with a significantly increased risk of all-cause mortality (level 1 RR = 2.35; 95% CI: 1.94–2.84, level 2 RR = 1.71; 95% CI: 1.45–2.00, level 3 RR = 1.30; 95% CI: 1.14–1.49, level 4 RR = 1.07; 95% CI: 0.95–1.22), compared with PA level 5. CVD mortality risk increased in PA levels 1–3 (level 1 RR = 3.50; 95% CI: 2.41–5.10, level 2 RR = 1.50; 95% CI: 0.99–2.25, level 3 RR = 1.12; 95% CI: 0.79–1.60) as did cancer mortality risk (RR = 1.32; 95% CI: 0.96–1.81, RR = 1.48; 95% CI: 1.19–1.84, RR = 1.26; 95% CI: 1.06–1.50, respectively). The magnitude of the associations was consistent across strata of age, smoking, and body mass index. The population attributable fractions for PA levels 1–4 were: all-cause mortality, 11.5%; CVD mortality, 11.3%; cancer mortality, 7.8%. There is a significant trend of increased risk of all-cause, CVD and cancer mortality in relation to low PA levels among Norwegian women

DNMT inhibitors reverse a specific signature of aberrant promoter DNA methylation and associated gene silencing in AML

&lt;b&gt;Background&lt;/b&gt;. Myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) are neoplastic disorders of hematopoietic stem cells. DNA methyltransferase inhibitors (DNMTi), 5-azacytidine (AzaC) and 5-aza-2’-deoxycytidine (Decitabine), benefit some MDS/AML patients. However, the role of DNMTi-induced DNA hypomethylation in regulation of gene expression in AML is unclear.&lt;p&gt;&lt;/p&gt; &lt;b&gt;Results. &lt;/b&gt; We compared the effects of AzaC on DNA methylation and gene expression using whole-genome single-nucleotide bisulfite-sequencing (WGBS) and RNA-sequencing in OCI-AML3 (AML3) cells. For data analysis, we used an approach recently developed for discovery of differential patterns of DNA methylation associated with changes in gene expression, that is tailored to single-nucleotide bisulfite-sequencing data (Washington University Interpolated Methylation Signatures (WIMSi)). By this approach, a subset of genes upregulated by AzaC was found to be characterized by AzaC-induced signature methylation loss flanking the transcription start site. These genes are enriched for genes increased in methylation and decreased in expression in AML3 cells compared to normal hematopoietic stem and progenitor cells. Moreover, these genes are preferentially upregulated by Decitabine in human primary AML blasts, and control cell proliferation, death and development. &lt;p&gt;&lt;/p&gt; &lt;b&gt;Conclusions.&lt;/b&gt; Our WGBS and WIMSi data analysis approach has identified a set of genes whose is methylation and silencing in AML is reversed by DNMTi. These genes are good candidates for direct regulation by DNMTi, and their reactivation by DNMTi may contribute to therapeutic activity. This study also demonstrates the ability of WIMSi to reveal relationships between DNA methylation and gene expression, based on single-nucleotide bisulfite-sequencing and RNA-seq data.&lt;p&gt;&lt;/p&gt

Barriers to and facilitators for making emergency calls – a qualitative interview study of stroke patients and witnesses

publishedVersio

Rusmidler i Norge 2011

Rusmidler i Norge inneholder oppdaterte tabeller om forbruk, økonomi, kriminalitet, skadevirkninger og behandling knyttet både til alkohol-, narkotika-, legemiddel- og tobakksbruk. Nytt av året er blant annet tall fra sprøyterommet i Oslo. Utgitt i over 20 år Det er over 20 år siden den første utgaven av Rusmidler i Norge kom ut, og SIRUS har hvert år siden gitt ut et hefte med fersk rusmiddelstatistikk. Tallmaterialet er hentet fra offentlig statistikk og SIRUS´ egne undersøkelser. For å gjøre statistikken tilgjengelig i en internasjonal sammenheng, presenteres all tekst også på engelsk. RusStat - statistikk på nett Alle tabeller er også lagt ut i SIRUS´ nettbaserte statistikkdatabase - RusStat. Basen blir oppdatert etter hvert som nytt tallmateriale kommer inn. Her finnes også lengre tidsserier på mange områder, bl.a. omsetning av alkohol i Norge fra 1800-tallet til i dag

The formation of high-mass binary star systems

KL acknowledges financial support from the Carnegie Trust. IAB acknowledges support from the ECOGAL project, grant agreement 291227, funded by the European Research Council under ERC-2011-ADG.We develop a semi-analytic model to investigate how accretion on to wide low-mass binary stars can result in a close high-mass binary system. The key ingredient is to allow mass accretion while limiting the gain in angular momentum. We envision this process as being regulated by an external magnetic field during infall. Molecular clouds are made to collapse spherically with material either accreting on to the stars or settling in a disc. Our aim is to determine what initial conditions are needed for the resulting binary to be both massive and close. Whether material accretes, and what happens to the binary separation as a result, depends on the relative size of its specific angular momentum, compared to the specific angular momentum of the binary. When we add a magnetic field we are introducing a torque to the system that is capable of stripping the molecular cloud of some of its angular momentum, and consequently easing the formation of high-mass binaries. Our results suggest that clouds in excess of 1000 M⊙ and radii of 0.5 pc or larger, can easily form binary systems with masses in excess of 25 M⊙ and separations of order 10 R⊙ with magnetic fields of order 100 μG (mass-to-flux ratios of order five).Publisher PDFPeer reviewe

Implementering av krav til kommersialisering av forskningsresultater ved Universitetet i Tromsø : PhD-kandidatenes holdninger og opplevelse av støtte i forbindelse med kommersialisering av forskningsresultater

Masteroppgave i bedriftsledelse (MBA) - Universitetet i Nordland, 201