27 research outputs found
Interprovincial Migration and Human Capital Formation in China*
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/122433/1/asej12089.pd
Deficit of Far-Infrared [CII] Line Emission toward the Galactic Center
We have observed the [CII] 158 micron line emission from the Galactic plane
(-10 deg < l < 25 deg, |b| <= 3 deg) with the Balloon-borne Infrared Carbon
Explorer (BICE). The observed longitudinal distribution of the [CII] line
emission is clearly different from that of the far-infrared continuum emission;
the Galactic center is not the dominant peak in the [CII] emission. Indeed, the
ratio of the [CII] line emission to far-infrared continuum (I_[CII] / I_FIR) is
systematically low within the central several hundred parsecs of the Galaxy.
The observational results indicate that the abundance of the C+ ions themselves
is low in the Galactic center. We attribute this low abundance mainly to soft
UV radiation with fewer C-ionizing photons. This soft radiation field, together
with the pervasively high molecular gas density, makes the molecular
self-shielding more effective in the Galactic center. The self-shielding
further reduces the abundance of C+ ions, and raises the temperature of
molecular gas at the C+/C/CO transition zone.Comment: Compressed uuencoded postcript, 15 pages with 2 figures, to appear in
the Astrophysical Journal (Letters
Large Silicon Abundance in Photodissociation Regions
We have made one-dimensional raster-scan observations of the rho Oph and
sigma Sco star-forming regions with two spectrometers (SWS and LWS) on board
the ISO. In the rho Oph region, [SiII] 35um, [OI] 63um, 146um, [CII] 158um, and
the H2 pure rotational transition lines S(0) to S(3) are detected, and the PDR
properties are derived as the radiation field scaled by the solar neighborhood
value G_0~30-500, the gas density n~250--2500 /cc, and the surface temperature
T~100-400 K. The ratio of [SiII] 35um to [OI] 146um indicates that silicon of
10--20% of the solar abundance must be in the gaseous form in the
photodissociation region (PDR), suggesting that efficient dust destruction is
undergoing even in the PDR and that part of silicon atoms may be contained in
volatile forms in dust grains. The [OI] 63um and [CII] 158um emissions are too
weak relative to [OI] 146um to be accounted for by standard PDR models. We
propose a simple model, in which overlapping PDR clouds along the line of sight
absorb the [OI] 63um and [CII] 158um emissions, and show that the proposed
model reproduces the observed line intensities fairly well. In the sigma Sco
region, we have detected 3 fine-structure lines, [OI] 63um, [NII] 122um, and
[CII] 158um, and derived that 30-80% of the [CII] emission comes from the
ionized gas. The upper limit of the [SiII] 35um is compatible with the solar
abundance relative to nitrogen and no useful constraint on the gaseous Si is
obtained for the sigma Sco region.Comment: 25 pages with 7 figures, accepted in Astrophysical Journa
DRD1, a SWI/SNF-like chromatin remodeling protein, regulates a heat-activated transposon in Arabidopsis thaliana
ONSEN is a heat-activated LTR retrotransposon in Arabidopsis thaliana. Screens to identify transcriptional regulatory factors of ONSEN revealed a SWI/SNF-like chromatin remodeling protein, DRD1, which cooperates with plant-specific RNA polymerase and is involved in RNA-directed DNA methylation. ONSEN transcript level was increased in the drd1 mutant relative to wild-type under heat stress, indicating that DRD1 plays a significant role in the silencing of activated ONSEN under the stress condition. The transcript level of HsfA2, which is directly involved in transcriptional activation of ONSEN, was not higher in the drd1 mutant than in the wild-type. Interestingly, no transgenerational transposition of ONSEN was observed in the drd1 mutant, even though DNA methylation levels were significantly reduced and expression levels were increased compared to the wild-type. These results suggest that other factors are involved in the regulation of ONSEN transposition in addition to the transcript level of ONSEN
Evaluation of refractive correction for standard automated perimetry in eyes wearing multifocal contact lenses
AIM: To evaluate the refractive correction for standard automated perimetry (SAP) in eyes with refractive multifocal contact lenses (CL) in healthy young participants.
METHODS: Twenty-nine eyes of 29 participants were included. Accommodation was paralyzed in all participants with 1% cyclopentolate hydrochloride. SAP was performed using the Humphrey SITA-standard 24-2 and 10-2 protocol under three refractive conditions: monofocal CL corrected for near distance (baseline); multifocal CL corrected for distance (mCL-D); and mCL-D corrected for near vision using a spectacle lens (mCL-N). Primary outcome measures were the foveal threshold, mean deviation (MD), and pattern standard deviation (PSD).
RESULTS: The foveal threshold of mCL-N with both the 24-2 and 10-2 protocols significantly decreased by 2.2-2.5 dB
CONCLUSION: Despite the induced mydriasis and the optical design of the multifocal lens used in this study, our results indicated that, when the dome-shaped visual field test is performed with eyes with large pupils and wearing refractive multifocal CLs, distance correction without additional near correction is to be recommended
ONSEN shows different transposition activities in RdDM pathway mutants
Most transposable elements (TEs) are tightly regulated by epigenetic mechanisms such as DNA methylation. RNA-directed DNA methylation (RdDM) is a major control mechanism of TE silencing in plants. We analyzed the transposition activity of a heat-responsive retrotransposon, ONSEN, in Arabidopsis thaliana. Transgenerational transposition was observed in RdDM pathway-deficient mutants upon heat stress. The transposition frequency was higher in the mutants of the upstream processes, but lower in the mutants of the downstream steps, of RdDM. The transposition frequency was not associated with the number of extrachromosomal ONSEN copies. Constitutive heterochromatin of interphase nuclei was dispersed upon heat stress. The degree of decondensation was higher in the RdDM mutants than in wild-type plants subjected to heat stress. We discuss the possible role of RdDM in the regulation of ONSEN transposition upon heat stress