Nemitz, Nils
Ohkubo, Takuya
Takamoto, Masao
Ushijima, Ichiro
Das, Manoj
Ohmae, Noriaki
Katori, Hidetoshi
Article History
Received: 30 November 2015
Accepted: 25 January 2016
First Online: 29 February 2016
Change Date: 15 March 2016
Change Type: Correction
Change Details: In the version of this Letter originally published online, in Table 2, the column heading '<sup>171</sup>Yb' was mistakenly included. This has now been corrected in all versions of the Letter.
Competing interests
: The authors declare no competing financial interests.