We have performed high-resolution angle-resolved photoemission spectroscopy on quasi-one-dimensional indium chains on the Si͑111͒ surface to study the temperature-induced metal-insulator ͑MI͒ transition accompanied by the 4 ϫ 1 to 8ϫ 2 structural change. The band dispersion near E F shows an abrupt change at 120 K, giving a relatively large energy gap compared to the energy scale of the transition temperature. The band dispersion of the 8 ϫ 2 phase shows no discernible temperature evolution, in sharp contrast to the conventional simple Peierls or structural transition. The experimental results suggest that the Peierls instability is important in the MI transition, while other structural effects are cooperatively involved.

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In this article, we described the spontaneously occurring mutation speciˆcities of defects that are involved in translesion polymerase, mutS mismatch correction and polA mismatch correction in Escherichia coli. We argue that 1) there is no contribution of translesion polymerase to E. coli chromosomal mutation, 2) mutS system recognizes and corrects transition and frameshift mismatches and 3) polA system recognizes and corrects deletion, frameshift and transition mismatches. We also characterized the genetic alterations that inactivate either the CAN1 gene of Saccharomyces cerevisiae haploid cells or heterozygously situated in diploid cells. The characteristics of mutation in haploid yeast are essentially consistent with those in E. coli, suggesting that similar mechanisms are operating to form spontaneous mutation. CAN1 ＋ /can1 -(Can S ) to can1 -/can1 -(Can R ) mutations in diploid cells could occur through recombination, mainly allelic crossover and gene conversion.