444 research outputs found
Fluorine-incorporation scheme in fluorinated amorphous silicon prepared by various methods.
Fluorinated amorphous silicon (a-Si:F) films are prepared by three different methods: glow-discharge decomposition of SiF2 gas, magnetron sputtering, and conventional diode sputtering. The incorporation scheme of F atoms is investigated by means of nuclear magnetic resonance (NMR) and infrared (ir) absorption measurements. 19F NMR signals observed at 4.2 K can be simulated by superposing signals from dispersed F atoms, clustered F atoms, SiF4 molecules, and SiF3 species. The content of SiF4 increases by annealing in agreement with an increase in the intensity of ir absorption at 1020 cm-1. 19F NMR signals at 77 K and at room temperature show the effect of motional narrowing because SiF4 molecules move easily in the amorphous network
Predominant Magnetic States in Hubbard Model on Anisotropic Triangular Lattices
Using an optimization variational Monte Carlo method, we study the
half-filled-band Hubbard model on anisotropic triangular lattices, as a
continuation of the preceding study [J. Phys. Soc. Jpn 75, 074707 (2006)]. We
introduce two new trial states: (i) A coexisting state of
(\pi,\pi)-antiferromagnetic (AF) and a d-wave singlet gaps, in which we allow
for a band renormalization effect, and (ii) a state with an AF order of
120^\circ spin structure. In both states, a first-order metal-to-insulator
transition occurs at smaller U/t than that of the pure d-wave state. In
insulating regimes, magnetic orders always exist; an ordinary (\pi,\pi)-AF
order survives up to t'/t\sim 0.9 (U/t=12), and a 120^\circ-AF order becomes
dominant for t'/t \gsim 0.9. The regimes of the robust superconductor and of
the nonmagnetic insulator the preceding study proposed give way to these
magnetic domains.Comment: 11 pages, 14 figure
A role for BiP as an adjustor for the endoplasmic reticulum stress-sensing protein Ire1
In the unfolded protein response, the type I transmembrane protein Ire1 transmits an endoplasmic reticulum (ER) stress signal to the cytoplasm. We previously reported that under nonstressed conditions, the ER chaperone BiP binds and represses Ire1. It is still unclear how this event contributes to the overall regulation of Ire1. The present Ire1 mutation study shows that the luminal domain possesses two subregions that seem indispensable for activity. The BiP-binding site was assigned not to these subregions, but to a region neighboring the transmembrane domain. Phenotypic comparison of several Ire1 mutants carrying deletions in the indispensable subregions suggests these subregions are responsible for multiple events that are prerequisites for activation of the overall Ire1 proteins. Unexpectedly, deletion of the BiP-binding site rendered Ire1 unaltered in ER stress inducibility, but hypersensitive to ethanol and high temperature. We conclude that in the ER stress-sensory system BiP is not the principal determinant of Ire1 activity, but an adjustor for sensitivity to various stresses
Can High Frequency Acoustic Waves Heat the Quiet Sun Chromosphere?
We use Hinode/SOT Ca II H-line and blue continuum broadband observations to
study the presence and power of high frequency acoustic waves at high spatial
resolution. We find that there is no dominant power at small spatial scales;
the integrated power using the full resolution of Hinode (0.05'' pixels, 0.16''
resolution) is larger than the power in the data degraded to 0.5'' pixels
(TRACE pixel size) by only a factor of 1.2. At 20 mHz the ratio is 1.6.
Combining this result with the estimates of the acoustic flux based on TRACE
data of Fossum & Carlsson (2006), we conclude that the total energy flux in
acoustic waves of frequency 5-40 mHz entering the internetwork chromosphere of
the quiet Sun is less than 800 W m, inadequate to balance the radiative
losses in a static chromosphere by a factor of five.Comment: 6 pages, 8 figures, accepted for publication in PASJ (special Hinode
issue
Whole-Genome Sequence of the Microcystin-Degrading Bacterium Sphingopyxis sp. Strain C-1
This report describes the whole-genome sequence of an alkalitolerant microcystin-degrading bacterium, Sphingopyxis sp. strain C-1, isolated from a lake in China
Observations of Sunspot Oscillations in G band and Ca II H line with Solar Optical Telescope on Hinode
Exploiting high-resolution observations made by the Solar Optical Telescope
onboard Hinode, we investigate the spatial distribution of power spectral
density of oscillatory signal in and around NOAA active region 10935. The
G-band data show that in the umbra the oscillatory power is suppressed in all
frequency ranges. On the other hand, in Ca II H intensity maps oscillations in
the umbra, so-called umbral flashes, are clearly seen with the power peaking
around 5.5 mHz. The Ca II H power distribution shows the enhanced elements with
the spatial scale of the umbral flashes over most of the umbra but there is a
region with suppressed power at the center of the umbra. The origin and
property of this node-like feature remain unexplained.Comment: 7 pages, 8 figures, accepted for publication in PASJ (Hinode Special
Issue
Hinode Calibration for Precise Image Co-alignment between SOT and XRT (November 2006 -- April 2007)
To understand the physical mechanisms for activity and heating in the solar
atmosphere, the magnetic coupling from the photosphere to the corona is an
important piece of information from the Hinode observations, and therefore
precise positional alignment is required among the data acquired by different
telescopes. The Hinode spacecraft and its onboard telescopes were developed to
allow us to investigate magnetic coupling with co-alignment accuracy better
than 1 arcsec. Using the Mercury transit observed on 8 November 2006 and
co-alignment measurements regularly performed on a weekly basis, we have
determined the information necessary for precise image co-alignment and have
confirmed that co-alignment better than 1 arcsec can be realized between Solar
Optical Telescope (SOT) and X-Ray Telescope (XRT) with our baseline
co-alignment method. This paper presents results from the calibration for
precise co-alignment of CCD images from SOT and XRT.Comment: 8 pages, 9 figures, accepted for publication in PASJ (Hinode Special
issue
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