High-precision CTE measurement of hybrid C/SiC composite for cryogenic space telescopes

This paper presents highly precise measurements of thermal expansion of a "hybrid" carbon-fiber reinforced silicon carbide composite, HB-Cesic\textregistered - a trademark of ECM, in the temperature region of \sim310-10K. Whilst C/SiC composites have been considered to be promising for the mirrors and other structures of space-borne cryogenic telescopes, the anisotropic thermal expansion has been a potential disadvantage of this material. HB-Cesic\textregistered is a newly developed composite using a mixture of different types of chopped, short carbon-fiber, in which one of the important aims of the development was to reduce the anisotropy. The measurements indicate that the anisotropy was much reduced down to 4% as a result of hybridization. The thermal expansion data obtained are presented as functions of temperature using eighth-order polynomials separately for the horizontal (XY-) and vertical (Z-) directions of the fabrication process. The average CTEs and their dispersion (1{\sigma}) in the range 293-10K derived from the data for the XY- and Z-directions were 0.805$\pm$0.003\times10$^{-6}$ K$^{-1}$ and 0.837\pm0.001\times10$^{-6}$ K$^{-1}$, respectively. The absolute accuracy and the reproducibility of the present measurements are suggested to be better than 0.01\times10$^{-6}$ K$^{-1}$ and 0.001\times(10)^{-6} K^{-1}, respectively. The residual anisotropy of the thermal expansion was consistent with our previous speculation regarding carbon-fiber, in which the residual anisotropy tended to lie mainly in the horizontal plane.Comment: Accepted by Cryogeincs. 12 pages, 3 figures, 1 tabll

Multi-wavelength analysis of 18um-selected galaxies in the AKARI/IRC monitor field towards the North Ecliptic Pole

We present an initial analysis of AKARI 18um-selected galaxies using all 9 photometric bands at 2-24um available in the InfraRed Camera (IRC), in order to demonstrate new capabilities of AKARI cosmological surveys. We detected 72 sources at 18um in an area of 50.2 arcmin^2 in the AKARI/IRC monitor field towards the North Ecliptic Pole (NEP). From this sample, 25 galaxies with probable redshifts z>~ 0.5 are selected with a single colour cut (N2-N3>0.1) for a detailed SED analysis with ground-based BVRi'z'JK data. Using an SED radiative transfer model of starbursts covering the wavelength range UV -- submm, we derive photometric redshifts from the optical-MIR SEDs of 18um-selected galaxies. From the best-fit SED models, we show that the IRC all-band photometry is capable of tracing the steep rise in flux at the blue side of the PAH 6.2um emission feature. This indicates that the IRC all-band photometry is useful to constrain the redshift of infrared galaxies, specifically for dusty galaxies with a less prominent 4000A break. Also, we find that the flux dip between the PAH 7.7 and 11.2um emission feature is recognizable in the observed SEDs of galaxies at z~1. By using such a colour anomaly due to the PAH and silicate absorption features, unique samples of ULIRGs at z~1, `silicate-break' galaxies, can be constructed from large cosmological surveys of AKARI towards the NEP, i.e. the NEP-Deep and NEP-Wide survey. This pilot study suggests the possibility of detecting many interesting galaxy properties in the NEP-Deep and Wide surveys, such as a systematic difference in SEDs between high- and low-z ULIRGs, and a large variation of the PAH inter-band strength ratio in galaxies at high redshifts. [abridged]Comment: Accepted for publication in PASJ, AKARI special issu

Planar shock wave generated by uniform irradiation from two overlapped partially coherent laser beams

Copyright 2001 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Journal of Applied Physics, 89(5), 2571-2575, 2001 and may be found at http://dx.doi.org/10.1063/1.134218

Aneuploidy Drives Genomic Instability in Yeast

Aneuploidy decreases cellular fitness, yet it is also associated with cancer, a disease of enhanced proliferative capacity. To investigate one mechanism by which aneuploidy could contribute to tumorigenesis, we examined the effects of aneuploidy on genomic stability. We analyzed 13 budding yeast strains that carry extra copies of single chromosomes and found that all aneuploid strains exhibited one or more forms of genomic instability. Most strains displayed increased chromosome loss and mitotic recombination, as well as defective DNA damage repair. Aneuploid fission yeast strains also exhibited defects in mitotic recombination. Aneuploidy-induced genomic instability could facilitate the development of genetic alterations that drive malignant growth in cancer

Scans for signatures of selection in Russian cattle breed genomes reveal new candidate genes for environmental adaptation and acclimation

Domestication and selective breeding has resulted in over 1000 extant cattle breeds. Many of these breeds do not excel in important traits but are adapted to local environments. These adaptations are a valuable source of genetic material for efforts to improve commercial breeds. As a step toward this goal we identified candidate regions to be under selection in genomes of nine Russian native cattle breeds adapted to survive in harsh climates. After comparing our data to other breeds of European and Asian origins we found known and novel candidate genes that could potentially be related to domestication, economically important traits and environmental adaptations in cattle. The Russian cattle breed genomes contained regions under putative selection with genes that may be related to adaptations to harsh environments (e.g., AQP5, RAD50, and RETREG1). We found genomic signatures of selective sweeps near key genes related to economically important traits, such as the milk production (e.g., DGAT1, ABCG2), growth (e.g., XKR4), and reproduction (e.g., CSF2). Our data point to candidate genes which should be included in future studies attempting to identify genes to improve the extant breeds and facilitate generation of commercial breeds that fit better into the environments of Russia and other countries with similar climates

Ultrafast observation of lattice dynamics in laser-irradiated gold foils

We have observed the lattice expansion before the onset of compression in an optical-laser-driven target, using diffraction of femtosecond X-ray beams generated by the SPring-8 Angstrom Compact Free-electron Laser. The change in diffraction angle provides a direct measure of the lattice spacing, allowing the density to be calculated with a precision of ±1%. From the known equation of state relations, this allows an estimation of the temperature responsible for the expansion as <1000 K. The subsequent ablation-driven compression was observed with a clear rise in density at later times. This demonstrates the feasibility of studying the dynamics of preheating and shock formation with unprecedented detail.N. J. Hartley, N. Ozaki, T. Matsuoka, B. Albertazzi, A. Faenov, Y. Fujimoto, H. Habara, M. Harmand, Y. Inubushi, T. Katayama, M. Koenig, A. Krygier, P. Mabey, Y. Matsumura, S. Matsuyama, E. E. McBride, K. Miyanishi, G. Morard, T. Okuchi, T. Pikuz, O. Sakata, Y. Sano, T. Sato, T. Sekine, Y. Seto, K. Takahashi, K. A. Tanaka, Y. Tange, T. Togashi, Y. Umeda, T. Vinci, M. Yabashi, T. Yabuuchi, K. Yamauchi, and R. Kodama , "Ultrafast observation of lattice dynamics in laser-irradiated gold foils", Appl. Phys. Lett. 110, 071905 (2017) https://doi.org/10.1063/1.4976541

Evidence for intron length conservation in a set of mammalian genes associated with embryonic development

<p>Abstract</p> <p>Background</p> <p>We carried out an analysis of intron length conservation across a diverse group of nineteen mammalian species. Motivated by recent research suggesting a role for time delays associated with intron transcription in gene expression oscillations required for early embryonic patterning, we searched for examples of genes that showed the most extreme conservation of total intron content in mammals.</p> <p>Results</p> <p>Gene sets annotated as being involved in pattern specification in the early embryo or containing the homeobox DNA-binding domain, were significantly enriched among genes with highly conserved intron content. We used ancestral sequences reconstructed with probabilistic models that account for insertion and deletion mutations to distinguish insertion and deletion events on lineages leading to human and mouse from their last common ancestor. Using a randomization procedure, we show that genes containing the homeobox domain show less change in intron content than expected, given the number of insertion and deletion events within their introns.</p> <p>Conclusions</p> <p>Our results suggest selection for gene expression precision or the existence of additional development-associated genes for which transcriptional delay is functionally significant.</p

Generation of pressures over 40 GPa using Kawai-type multi-anvil press with tungsten carbide anvils

We have generated over 40 GPa pressures, namely, 43 and 44 GPa, at ambient temperature and 2000 K, respectively, using Kawai-type multi-anvil presses (KMAP) with tungsten carbide anvils for the first time. These high-pressure generations were achieved by combining the following pressure-generation techniques: (1) precisely aligned guide block systems, (2) high hardness of tungsten carbide, (3) tapering of second-stage anvil faces, (4) materials with high bulk modulus in a high-pressure cell, and (5) high heating efficiency

Indirect monitoring shot-to-shot shock waves strength reproducibility during pump-probe experiments

We present an indirect method of estimating the strength of a shock wave, allowing on line monitoring of its reproducibility in each laser shot. This method is based on a shot-to-shot measurement of the X-ray emission from the ablated plasma by a high resolution, spatially resolved focusing spectrometer. An optical pump laser with energy of 1.0 J and pulse duration of ∼660 ps was used to irradiate solid targets or foils with various thicknesses containing Oxygen, Aluminum, Iron, and Tantalum. The high sensitivity and resolving power of the X-ray spectrometer allowed spectra to be obtained on each laser shot and to control fluctuations of the spectral intensity emitted by different plasmas with an accuracy of ∼2%, implying an accuracy in the derived electron plasma temperature of 5%-10% in pump-probe high energy density science experiments. At nano- and sub-nanosecond duration of laser pulse with relatively low laser intensities and ratio Z/A ∼ 0.5, the electron temperature follows Te ∼ Ilas2/3. Thus, measurements of the electron plasma temperature allow indirect estimation of the laser flux on the target and control its shot-to-shot fluctuation. Knowing the laser flux intensity and its fluctuation gives us the possibility of monitoring shot-to-shot reproducibility of shock wave strength generation with high accuracy.T. A. Pikuz, A. Ya. Faenov, N. Ozaki, N. J. Hartley, B. Albertazzi, T. Matsuoka, K. Takahashi, H. Habara, Y. Tange, S. Matsuyama, K. Yamauchi, R. Ochante, K. Sueda, O. Sakata, T. Sekine, T. Sato, Y. Umeda, Y. Inubushi, T. Yabuuchi, T. Togashi, T. Katayama, M. Yabashi, M. Harmand, G. Morard, M. Koenig, V. Zhakhovsky, N. Inogamov, A. S. Safronova, A. Stafford, I. Yu. Skobelev, S. A. Pikuz, T. Okuchi, Y. Seto, K. A. Tanaka, T. Ishikawa, and R. Kodama, "Indirect monitoring shot-to-shot shock waves strength reproducibility during pump–probe experiments", Journal of Applied Physics 120, 035901 (2016) https://doi.org/10.1063/1.4958796

The CCR4-NOT Complex Is Implicated in the Viability of Aneuploid Yeasts

To identify the genes required to sustain aneuploid viability, we screened a deletion library of non-essential genes in the fission yeast Schizosaccharomyces pombe, in which most types of aneuploidy are eventually lethal to the cell. Aneuploids remain viable for a period of time and can form colonies by reducing the extent of the aneuploidy. We hypothesized that a reduction in colony formation efficiency could be used to screen for gene deletions that compromise aneuploid viability. Deletion mutants were used to measure the effects on the viability of spores derived from triploid meiosis and from a chromosome instability mutant. We found that the CCR4-NOT complex, an evolutionarily conserved general regulator of mRNA turnover, and other related factors, including poly(A)-specific nuclease for mRNA decay, are involved in aneuploid viability. Defective mutations in CCR4-NOT complex components in the distantly related yeast Saccharomyces cerevisiae also affected the viability of spores produced from triploid cells, suggesting that this complex has a conserved role in aneuploids. In addition, our findings suggest that the genes required for homologous recombination repair are important for aneuploid viability