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This is an Issue edsumm for 934. Identification of the Palaeocene/Eocene thermal maximum in a marine sedimentary sequence shows that sea surface temperatures near the North Pole increased from roughly 18 degrees Celsius to over 23 degrees Celsius — such warm values imply the absence of ice and thus exclude the influence of ice-albedo feedbacks on this Arctic warming.
Improved photostability of fluorescent proteins would benefit many applications but is usually an afterthought in selection screens. Setting photostability as the primary selection criterion in screens for improved fluorescent proteins yielded highly photostable variants of existing orange and red fluorescent proteins without compromising other beneficial characteristics.