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Institution

University of Turku

EducationTurku, Finland
About: University of Turku is a education organization based out in Turku, Finland. It is known for research contribution in the topics: Population & Galaxy. The organization has 16296 authors who have published 45124 publications receiving 1505428 citations. The organization is also known as: Turun yliopisto & Åbo universitet.


Papers
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Journal ArticleDOI
TL;DR: In this article, an extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log(L) = 43.47 (erg s^(−1)).
Abstract: Extended optical and near-IR observations reveal that SN 2009dc shares a number of similarities with normal Type Ia supernovae (SNe Ia), but is clearly overluminous, with a (pseudo-bolometric) peak luminosity of log (L) = 43.47 (erg s^(−1)). Its light curves decline slowly over half a year after maximum light [Δm_(15)(B)_true= 0.71], and the early-time near-IR light curves show secondary maxima, although the minima between the first and the second peaks are not very pronounced. The bluer bands exhibit an enhanced fading after ~200 d, which might be caused by dust formation or an unexpectedly early IR catastrophe. The spectra of SN 2009dc are dominated by intermediate-mass elements and unburned material at early times, and by iron-group elements at late phases. Strong C ii lines are present until ~2 weeks past maximum, which is unprecedented in thermonuclear SNe. The ejecta velocities are significantly lower than in normal and even subluminous SNe Ia. No signatures of interaction with a circumstellar medium (CSM) are found in the spectra. Assuming that the light curves are powered by radioactive decay, analytic modelling suggests that SN 2009dc produced ~1.8 M_⊙ of ^(56)Ni assuming the smallest possible rise time of 22 d. Together with a derived total ejecta mass of ~2.8 M_⊙, this confirms that SN 2009dc is a member of the class of possible super-Chandrasekhar-mass SNe Ia similar to SNe 2003fg, 2006gz and 2007if. A study of the hosts of SN 2009dc and other superluminous SNe Ia reveals a tendency of these SNe to explode in low-mass galaxies. A low metallicity of the progenitor may therefore be an important prerequisite for producing superluminous SNe Ia. We discuss a number of possible explosion scenarios, ranging from super-Chandrasekhar-mass white-dwarf progenitors over dynamical white-dwarf mergers and Type I(1/2) SNe to a core-collapse origin of the explosion. None of the models seems capable of explaining all properties of SN 2009dc, so that the true nature of this SN and its peers remains nebulous.

221 citations

Journal ArticleDOI
TL;DR: It is reported that mtDNA replication disorders caused by TWINKLE mutations-mitochondrial myopathy (MM) and infantile onset spinocerebellar ataxia (IOSCA)-remodel cellular dNTP pools in mice are reported and targets for metabolic therapy are offered.

220 citations

Journal ArticleDOI
TL;DR: Future challenges include the incorporation of one or more probiotics together or in combination with suitable prebiotic substrates to enhance the efficacy of the preparations for clinical use.

220 citations

Journal ArticleDOI
TL;DR: Dietary supplementation of bifidobacteria typical for healthy infants, may be beneficial in the treatment of allergic disorders and suggests a correlation between allergic disease and the composition of the intestinal bifIDobacteria flora which has reduced adhesive abilities to the intestinal mucus.
Abstract: Fifty bifidobacteria strains were isolated from fecal samples of allergic and age matched healthy infants. Allergic infants were found to have an adult type Bifidobacterium flora with high levels of Bifidobacterium adolescentis. Healthy infants had a typical infant Bifidobacterium flora with high levels of Bifidobacterium bifidum. These isolates were tested for their adhesive properties to human intestinal mucus. The adhesion of the fecal bifidobacteria from healthy infants was significantly higher (P<0.0001) than for allergic infants. This suggests a correlation between allergic disease and the composition of the intestinal bifidobacteria flora which has reduced adhesive abilities to the intestinal mucus. Therefore, dietary supplementation of bifidobacteria typical for healthy infants, may be beneficial in the treatment of allergic disorders.

220 citations

Journal ArticleDOI
TL;DR: In this article, the effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs were determined for which high accuracy optical and infrared photometry is available, using the flux ratio in different bands as a proxy of both effective temperature and metallicity.
Abstract: We empirically determine effective temperatures and bolometric luminosities for a large sample of nearby M dwarfs, for which high accuracy optical and infrared photometry is available. We introduce a new technique which exploits the flux ratio in different bands as a proxy of both effective temperature and metallicity. Our temperature scale for late-type dwarfs extends well below 3000 K (almost to the brown dwarf limit) and is supported by interferometric angular diameter measurements above 3000 K. Our metallicities are in excellent agreement (usually within 0.2 dex) with recent determinations via independent techniques. A subsample of cool M dwarfs with metallicity estimates based on hotter Hipparcos common proper motion companions indicates our metallicities are also reliable below 3000 K, a temperature range unexplored until now. The high quality of our data allows us to identify a striking feature in the bolometric luminosity versus temperature plane, around the transition from K to M dwarfs. We have compared our sample of stars with theoretical models and conclude that this transition is due to an increase in the radii of the M dwarfs, a feature which is not reproduced by theoretical models.

220 citations


Authors

Showing all 16461 results

NameH-indexPapersCitations
Kari Alitalo174817114231
Mika Kivimäki1661515141468
Jaakko Kaprio1631532126320
Veikko Salomaa162843135046
Markus W. Büchler148154593574
Eugene C. Butcher14644672849
Steven Williams144137586712
Terho Lehtimäki1421304106981
Olli T. Raitakari1421232103487
Pim Cuijpers13698269370
Jeroen J. Bax132130674992
Sten Orrenius13044757445
Aarno Palotie12971189975
Stefan W. Hell12757765937
Carlos López-Otín12649483933
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023102
2022290
20212,673
20202,688
20192,407
20182,189