@article{FuerstLevermann2012, author = {F{\"u}rst, Johannes J. and Levermann, Anders}, title = {A minimal model for wind- and mixing-driven overturning threshold behavior for both driving mechanisms}, series = {Climate dynamics : observational, theoretical and computational research on the climate system}, volume = {38}, journal = {Climate dynamics : observational, theoretical and computational research on the climate system}, number = {1-2}, publisher = {Springer}, address = {New York}, issn = {0930-7575}, doi = {10.1007/s00382-011-1003-7}, pages = {239 -- 260}, year = {2012}, abstract = {We present a minimal conceptual model for the Atlantic meridional overturning circulation which incorporates the advection of salinity and the basic dynamics of the oceanic pycnocline. Four tracer transport processes following Gnanadesikan in Science 283(5410):2077-2079, (1999) allow for a dynamical adjustment of the oceanic pycnocline which defines the vertical extent of a mid-latitudinal box. At the same time the model captures the salt-advection feedback (Stommel in Tellus 13(2):224-230, (1961)). Due to its simplicity the model can be solved analytically in the purely wind- and purely mixing-driven cases. We find the possibility of abrupt transition in response to surface freshwater forcing in both cases even though the circulations are very different in physics and geometry. This analytical approach also provides expressions for the critical freshwater input marking the change in the dynamics of the system. Our analysis shows that including the pycnocline dynamics in a salt-advection model causes a decrease in the freshwater sensitivity of its northern sinking up to a threshold at which the circulation breaks down. Compared to previous studies the model is restricted to the essential ingredients. Still, it exhibits a rich behavior which reaches beyond the scope of this study and might be used as a paradigm for the qualitative behaviour of the Atlantic overturning in the discussion of driving mechanisms.}, language = {en} } @article{KhalilRailaAlietal.2012, author = {Khalil, Mahmoud and Raila, Jens and Ali, Mostafa and Islam, Khan M. S. and Schenk, Regina and Krause, Jens-Peter and Schweigert, Florian J. and Rawel, Harshadrai Manilal}, title = {Stability and bioavailability of lutein ester supplements from Tagetes flower prepared under food processing conditions}, series = {Journal of functional food}, volume = {4}, journal = {Journal of functional food}, number = {3}, publisher = {Elsevier}, address = {Amsterdam}, issn = {1756-4646}, doi = {10.1016/j.jff.2012.03.006}, pages = {602 -- 610}, year = {2012}, abstract = {Tagetes spp. belongs to the Asteraceae family. It is recognized as a major source of lutein ester (lutein esterified with fatty acids such as lauric, myristic and palmitic acids), a natural colorant belonging to the xanthophylls or oxygenated carotenoids. Four species of Tagetes flower (Tagetes tenuifolia, Tagetes erecta, Tagetes patula, and Tagetes lucida) were used to extract lutein and lutein esters with three different methods. The results showed that T. erecta, type "orangeprinz", is the richest source of lutein esters (14.4 +/- 0.234 mg/g) in comparison to other Tagetes spp. No significant differences between extractions of lutein esters with medium-chain triacylglycerols (MCT) oil, orange oil or solvent (hexane/isopropanol) could be observed. MCT oil also improved stability of lutein esters at 100 degrees C for 40 min. Emulsification of MCT oil improved the stability of lutein ester extract against UV light at 365 nm for 72 h. Finally, an emulsion was prepared under food processing conditions, spray dried and its bioavailability investigated in a preliminary human intervention study. The results show a lower resorption, but further data suggest improvements in implementation of such supplements. (c) 2012 Elsevier Ltd. All rights reserved.}, language = {en} }