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Davis, CA, United States

Carotenoids (C40) are synthesized in plastids and perform numerous important functions in these organelles. In addition, carotenoids can be processed into smaller signaling molecules that regulate various phases of the plant's life cycle. Besides the relatively well-studied phytohormones abscisic acid (ABA) and strigolactones (SLs), additional carotenoid-derived signaling molecules have been discovered and shown to regulate plant growth and development. As a few excellent reviews summarized recent research on ABA and SLs, this mini review will focus on progress made on identification and characterization of the emerging carotenoid-derived signals. Overall, a better understanding of carotenoid-derived signaling molecules has immediate applications in improving plant biomass production which in turn will have far reaching impacts on providing food, feed, and fuel for the growing world population. © 2015 Tian.

Wasson J.T.,UniversityofCalifornia
Earth and Planetary Science Letters | Year: 2013

Most researchers hold that the HED clan of differentiated meteorites originated on Vesta largely based on the assumption that nearly all V-type asteroids with basaltic reflection spectra are fragments spalled off Vesta. Although it is a reasonable working hypothesis that most of the V-type asteroids in the Vesta family originated on Vesta, the spectra are not unique enough to confirm this; a sizable fraction may have been produced during the destruction of a differentiated asteroid in the same large region of dynamic space. Observations of asteroids in the inner Asteroid Belt show that more than half of the V-type asteroids do not belong to the Vesta dynamic family.Iron-meteorite evidence shows that at least 26 asteroids experienced extensive melting and would have generated basalts and other differentiated stony meteorites. Most iron meteorites show high degrees of elemental fractionations that lead to the conclusion that they experienced fractional crystallization; it is probable that all these bodies generated basalts. There are 9 of these "magmatic" iron-meteorite groups and test criteria mainly based on extreme fractionations indicate that an additional 17 disrupted asteroids hosted fractionally crystallized cores and thus that ≥26 asteroids experienced extensive melting; this estimate is much lower than previous estimates that included nonmagmatic irons.Within expected planetary heterogeneities the O-isotopic composition of HEDs is the same as that in oxides from IIIAB irons, the largest magmatic group of iron meteorites. εCr54 values are also very similar in IIIABs and HEDs. The O- and Cr-isotopic ties are much stronger than the spectral tie thus the working hypothesis should be that HEDs are from the IIIAB parent asteroid.Remote elemental analysis could confirm that HEDs are not from Vesta. If future remote analysis measures K contents ≥0.6 mg/g this will indicate that HEDs did not originate on Vesta. © 2013.

Slebarski A.,University of Silesia | Slebarski A.,UniversityofCalifornia | Maple M.B.,UniversityofCalifornia | Fijalkowski M.,University of Silesia | Goraus J.,University of Silesia
Journal of Physics Condensed Matter | Year: 2010

CeNiSn is known as a semimetallic system with a small pseudogap at the Fermi energy. We investigate the effect of Rh doping on the Kondo insulator CeNiSn by means of measurements of ac magnetic susceptibility and specific heat. We show that the formation of the Kondo insulator narrow gap in CeNi 1-xRhxSn is associated with disorder-induced f-electron localization. For doped CeNiSn with x ≤ 0.06, the electrical resistivity data follow an activation and variable range hopping behaviour at low T, consistent with weak disorder and localization, while C/T is large, which is not a common feature of Kondo insulators. For x > 0.06, the system is metallic and exhibits non-Fermi liquid behaviour with magnetic susceptibility χ ∼ T-n with n ∼ 0.4 and electrical resistivity ρ ∼ T. © 2010 IOP Publishing Ltd.

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