The origin of Tibetans remains one of the most contentious puzzles in history, anthropology, and genetics. Analyses of deeply sequenced (30×-60×) genomes of 38 Tibetan highlanders and 39 Han Chinese lowlanders, together with available data on archaic and modern humans, allow us to comprehensively characterize the ancestral makeup of Tibetans and uncover their origins. Non-modern human sequences compose ∼6% of the Tibetan gene pool and form unique haplotypes in some genomic regions, where Denisovan-like, Neanderthal-like, ancient-Siberian-like, and unknown ancestries are entangled and elevated. The shared ancestry of Tibetan-enriched sequences dates back to ∼62,000-38,000 years ago, predating the Last Glacial Maximum (LGM) and representing early colonization of the plateau. Nonetheless, most of the Tibetan gene pool is of modern human origin and diverged from that of Han Chinese ∼15,000 to ∼9,000 years ago, which can be largely attributed to post-LGM arrivals. Analysis of ∼200 contemporary populations showed that Tibetans share ancestry with populations from East Asia (∼82%), Central Asia and Siberia (∼11%), South Asia (∼6%), and western Eurasia and Oceania (∼1%). Our results support that Tibetans arose from a mixture of multiple ancestral gene pools but that their origins are much more complicated and ancient than previously suspected. We provide compelling evidence of the co-existence of Paleolithic and Neolithic ancestries in the Tibetan gene pool, indicating a genetic continuity between pre-historical highland-foragers and present-day Tibetans. In particular, highly differentiated sequences harbored in highlanders' genomes were most likely inherited from pre-LGM settlers of multiple ancestral origins (SUNDer) and maintained in high frequency by natural selection.

The failure mechanism of graphite/LiNi 0.5 Mn 1.5 O 4 cells cycled at 25 • C and 55 • C have been analyzed by electrochemical methods and ex-situ surface analysis of the electrodes. Graphite /LiNi 0.5 Mn 1.5 O 4 cells cycle well at 25 • C, but have rapid capacity fade upon cycling at 55 • C. Independent electrochemical analysis of anodes and cathodes extracted from cells cycled at 55 • C suggest that both electrodes have significant capacity loss, although the cathode capacity can be recovered with longer charging times. Ex-situ surface analysis of the cathode with SEM reveals that the bulk cathode particles and the cathode laminate are retained while XPS confirms the presence of a cathode electrolyte interface composed of the decomposition products of the electrolyte. Ex-situ analysis of the anode reveals a thick anode solid electrolyte interphase (SEI), anode delamination, and the presence of Mn. The results suggest that both the anode and the cathode contribute to performance loss in graphite/LiNi 0.5 Mn 1.5 O 4 cells.

BackgroundHan Chinese, Japanese and Korean, the three major ethnic groups of East Asia, share many similarities in appearance, language and culture etc., but their genetic relationships, divergence times and subsequent genetic exchanges have not been well studied.ResultsWe conducted a genome-wide study and evaluated the population structure of 182 Han Chinese, 90 Japanese and 100 Korean individuals, together with the data of 630 individuals representing 8 populations wordwide. Our analyses revealed that Han Chinese, Japanese and Korean populations have distinct genetic makeup and can be well distinguished based on either the genome wide data or a panel of ancestry informative markers (AIMs). Their genetic structure corresponds well to their geographical distributions, indicating geographical isolation played a critical role in driving population differentiation in East Asia. The most recent common ancestor of the three populations was dated back to 3000 ~ 3600 years ago. Our analyses also revealed substantial admixture within the three populations which occurred subsequent to initial splits, and distinct gene introgression from surrounding populations, of which northern ancestral component is dominant.ConclusionsThese estimations and findings facilitate to understanding population history and mechanism of human genetic diversity in East Asia, and have implications for both evolutionary and medical studies.Electronic supplementary materialThe online version of this article (10.1186/s41065-018-0057-5) contains supplementary material, which is available to authorized users.