Band structure and optical properties of germanium sheet polymers

The band structure of H-terminated Ge sheet polymers is calculated using density-functional theory in the local density approximation and compared to the optical properties of epitaxial polygermyne layers as determined from reflection, photoluminescence, and photoluminescence excitation measurements. A direct band gap of 1.7 eV is predicted and a near resonant excitation of the photoluminescence is observed experimentally close to this energy

Simple sequence repeat-based mini-core collection for white Guinea yam (Dioscorea rotundata) germplasm

Open Access Article; Published online: 07 Dec 2020A core subset with a small number of accessions representing the genetic diversity of the base collection plays a vital role in facilitating efficient utilization of plant genetic resources. This is particularly relevant for vegetatively propagated large plant size tuber crops with a long growing period, such as white Guinea yam (Dioscorea rotundata Poir.). For the efficient utilization of D. rotundata genetic resources, this study was aimed at developing a mini‐core collection from a core collection of 447 D. rotundata accessions maintained at the International Institute of Tropical Agriculture (IITA). Accordingly, a D. rotundata mini‐core collection representing 102 accessions was selected using 16 simple sequence repeat (SSR) markers, retaining ∼98% of the SSR allelic diversity of the base collection. A similar level of diversity was captured within the mini‐core collection and the base collection with respect to 21 morphological traits, ploidy level, and geographic origin. The mini‐core collection demonstrated a wide range of variation in agronomic traits such as growth period, number of tubers, average tuber weight, and total yield per plant. This variation was considerable when compared with the variation observed for the same traits among the 10 lines or genotypes conventionally used in the breeding program at IITA, which were included in this study as checks. The selected mini‐core accessions could serve as a working collection to broaden the genetic variation for use in practical breeding programs, as well as in future genomic analyses aimed at the genetic improvement of D. rotundata in West Africa

Chirality scenario of the spin-glass ordering

Detailed account is given of the chirality scenario of experimental spin-glass transitions. In this scenario, the spin glass order of weakly anisotropic Heisenberg-like spin-glass magnets including canonical spin glasses are essentially chirality driven. Recent numerical and experimental results are discussed in conjunction with this scenario.Comment: Submitted to J. Phys. Soc. Japan "Special Issue on Frustration

Gingival Fibroblasts as a Promising Source of Induced Pluripotent Stem Cells

Induced pluripotent stem (iPS) cells efficiently generated from accessible tissues have the potential for clinical applications. Oral gingiva, which is often resected during general dental treatments and treated as biomedical waste, is an easily obtainable tissue, and cells can be isolated from patients with minimal discomfort.We herein demonstrate iPS cell generation from adult wild-type mouse gingival fibroblasts (GFs) via introduction of four factors (Oct3/4, Sox2, Klf4 and c-Myc; GF-iPS-4F cells) or three factors (the same as GF-iPS-4F cells, but without the c-Myc oncogene; GF-iPS-3F cells) without drug selection. iPS cells were also generated from primary human gingival fibroblasts via four-factor transduction. These cells exhibited the morphology and growth properties of embryonic stem (ES) cells and expressed ES cell marker genes, with a decreased CpG methylation ratio in promoter regions of Nanog and Oct3/4. Additionally, teratoma formation assays showed ES cell-like derivation of cells and tissues representative of all three germ layers. In comparison to mouse GF-iPS-4F cells, GF-iPS-3F cells showed consistently more ES cell-like characteristics in terms of DNA methylation status and gene expression, although the reprogramming process was substantially delayed and the overall efficiency was also reduced. When transplanted into blastocysts, GF-iPS-3F cells gave rise to chimeras and contributed to the development of the germline. Notably, the four-factor reprogramming efficiency of mouse GFs was more than 7-fold higher than that of fibroblasts from tail-tips, possibly because of their high proliferative capacity.These results suggest that GFs from the easily obtainable gingival tissues can be readily reprogrammed into iPS cells, thus making them a promising cell source for investigating the basis of cellular reprogramming and pluripotency for future clinical applications. In addition, high-quality iPS cells were generated from mouse GFs without Myc transduction or a specific system for reprogrammed cell selection

Wp index: A new substorm index derived from high-resolution geomagnetic field data at low latitude

Geomagnetic field data with high time resolution (typically 1 s) have recently become more commonly acquired by ground stations. Such high time resolution data enable identifying Pi2 pulsations which have periods of 40–150 s and irregular (damped) waveforms. It is well-known that pulsations of this type are clearly observed at mid- and low-latitude ground stations on the nightside at substorm onset. Therefore, with 1-s data from multiple stations distributed in longitude around the Earth's circumference, substorm onset can be regularly monitored. In the present study we propose a new substorm index, the Wp index (Wave and planetary), which reflects Pi2 wave power at low-latitude, using geomagnetic field data from 11 ground stations. We compare the Wp index with the AE and ASY indices as well as the electron flux and magnetic field data at geosynchronous altitudes for 11 March 2010. We find that significant enhancements of the Wp index mostly coincide with those of the other data. Thus the Wp index can be considered a good indicator of substorm onset. The Wp index, other geomagnetic indices, and geosynchronous satellite data are plotted in a stack for quick and easy search of substorm onset. The stack plots and digital data of the Wp index are available at the Web site (http://s-cubed.info) for public use. These products would be useful to investigate and understand space weather events, because substorms cause injection of intense fluxes of energetic electrons into the inner magnetosphere and potentially have deleterious impacts on satellites by inducing surface charging

Observation of Large CP Violation in the Neutral B Meson System

We present a measurement of the Standard Model CP violation parameter sin 2phi_1 based on a 29.1 fb^{-1} data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is fully reconstructed as a J/psi Ks, psi(2S) Ks, chi_c1 Ks, eta_c Ks, J/psi K_L or J/psi K^{*0} decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin 2phi_1 = 0.99 +- 0.14(stat) +- 0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.Comment: 4 figures, to appear in Phys. Rev. Letter

Evidence for Direct CP Violation in B0 -> K+- pi-+ Decays

We report evidence for direct CP violation in the decay B0 -> K+-pi-+ with 253/fb of data collected with the Belle detector at the KEKB e+e- collider. Using 275 million B B_bar pairs we observe a B -> K+-pi-+ signal with 2140+-53 events. The measured CP violating asymmetry is Acp(K+-pi-+) = -0.101+-0.025 (stat)+-0.005 (syst), corresponding to a significance of 3.9 sigma including systematics. We also search for CP violation in the decays B+- -> K+-pi0 and B+- -> pi+-pi0. The measured CP violating asymmetries are Acp(K+-pi0) = 0.04+-0.05(stat)+-0.02(syst) and Acp(pi+-pi0) = -0.02+-0.10(stat)+-0.01(syst), corresponding to the intervals -0.05 < Acp(K+-pi0) < 0.13 and -0.18<Acp(pi+-pi0)<0.14 at 90% confidence level.Comment: 9 pages, 3 figures. submitted to Physical Review Letter