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- Bitsch, Bertram, et al.
(författare)
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The structure of protoplanetary discs around evolving young stars
- 2015
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Ingår i: Astronomy & Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 575
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Tidskriftsartikel (refereegranskat)abstract
- The formation of planets with gaseous envelopes takes place in protoplanetary accretion discs on time scales of several million years. Small dust particles stick to each other to form pebbles, pebbles concentrate in the turbulent flow to form planetesimals and planetary embryos and grow to planets, which undergo substantial radial migration. All these processes are influenced by the underlying structure of the protoplanetary disc, specifically the profiles of temperature, gas scale height, and density. The commonly used disc structure of the minimum mass solar nebula (MMSN) is a simple power law in all these quantities. However, protoplanetary disc models with both viscous and stellar heating show several bumps and dips in temperature, scale height, and density caused by transitions in opacity, which are missing in the MMSN model. These play an important role in the formation of planets, since they can act as sweet spots for forming planetesimals via the streaming instability and affect the direction and magnitude of type-I migration. We present 2D simulations of accretion discs that feature radiative cooling and viscous and stellar heating, and they are linked to the observed evolutionary stages of protoplanetary discs and their host stars. These models allow us to identify preferred planetesimal and planet formation regions in the protoplanetary disc as a function of the disc's metallicity, accretion rate, and lifetime. We derive simple fitting formulae that feature all structural characteristics of protoplanetary discs during the evolution of several Myr. These fits are straightforward for applying to modelling any growth stage of planets where detailed knowledge of the underlying disc structure is required.
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| 2. |
- von Wowern, Emma, et al.
(författare)
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Can flavonoid-rich chocolate modulate arterial elasticity and pathological uterine artery Doppler blood flow in pregnant women? A pilot study
- 2017
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Ingår i: Journal of Maternal-Fetal and Neonatal Medicine. - : Informa UK Limited. - 1476-7058 .- 1476-4954. ; , s. 1-6
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Dark chocolate has shown beneficial effects on cardiovascular health and might also modulate hypertensive complications in pregnancy and uteroplacental blood flow. Increased uteroplacental resistance is associated with systemic arterial stiffness. We aimed to investigate the short-term effect of flavonoid-rich chocolate on arterial stiffness and Doppler blood flow velocimetry indexes in pregnant women with compromised uteroplacental blood flow. Methods: Doppler blood flow velocimetry and digital pulse wave analysis (DPA) were performed in 25 women pregnant in the second and third trimesters with uterine artery (UtA) score (UAS) 3–4, before and after 3 days of ingestion of chocolate with high flavonoid and antioxidant contents. UtA pulsatility index (PI), UtA diastolic notching, UAS (semiquantitative measure of PI and notching combined), and umbilical artery PI were calculated, and DPA variables representing central and peripheral maternal arteries were recorded. Results: Mean UtA PI (p = .049) and UAS (p = .025) significantly decreased after chocolate consumption. There were no significant changes in UtA diastolic notching or any DPA indexes of arterial stiffness/vascular tone. Conclusion: Chocolate may have beneficial effects on the uteroplacental circulation, but in this pilot study, we could not demonstrate effects on arterial vascular tone as assessed by DPA.
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| 6. |
- Choi, Soon-Gwon
(författare)
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Knowledge translation in the internationalization of firms
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- International firms work in a complicated business environment that forces them to acquire various kinds of information and knowledge. Firms satisfy their need for knowledge about products, markets and business actors through learning from other firms. Because knowledge of relevance to international business is often tied in with a specific context, new knowledge has to be modified and adapted to fit the new market and organizational context. However, the importance of modification of knowledge is less developed in previous studies about knowledge transfer. Previous studies tend to focus the effects of characteristics of knowledge in the knowledge transfer process. To extend this view, I suggest a new and developed concept, knowledge translation, which is more focused on how knowledge is modified and developed as a firm identifies and assimilates it. The main purpose of this thesis is to conceptualize and describe knowledge translation in internationalization of the firms. For this purpose, I do LISREL analysis of quantitative data from the international project 'Learning in the internationalization of firms' and two case studies. This study shows that the concept of knowledge translation is a good framework for understanding knowledge modification and development in the internationalization process of the firms. That is, it shows that new knowledge is translated into the new context in a process of development and modification that is determined by the firms existing knowledge base. Results also show that knowledge translation is dependent on the firms previous experience and the depth of relationship development with the firm from which they translate knowledge. The results point to the idea that knowledge translation is a path dependent and relationship dependent phenomenon.
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