428 research outputs found
Analysing the Geopolitics of Contemporary Eurasia : EU-Hungarian Estrangement over the EU’s China Policy
The Trends and Problems of the Studies on the EU Politics and the European Parliament in Japan
Japanese Perceptions of the EU : The Need for a Longer Perspective to Ensure a Balanced Understanding
The EU\u27s \u27Hamilton Moment\u27 : Evaluating the 2020 Recovery Fund as a Significant Step towards Financial and Fiscal Integration
The European Union and North Korea : Possibilities and Limitations of the EU Diplomacy over the Korean Peninsula
The Number Density of Old Passively-Evolving Galaxies at z=1 in the Subaru/XMM-Newton Deep Survey Field
We obtained the number counts and the rest-frame B-band luminosity function
of the color-selected old passively-evolving galaxies (OPEGs) at z=1 with very
high statistical accuracy using a large and homogeneous sample of about 4000
such objects with z' <25 detected in the area of 1.03 deg^2 in the
Subaru/XMM-Newton Deep Survey (SXDS) field. Our selection criteria are defined
on the i'-z' and R-z' color-magnitude plane so that OPEGs at z=0.9-1.1 with
formation redshift z_f=2-10 are properly sampled. The limiting magnitude
corresponds to the luminosity of galaxies with M_*+3 at z=0. We made a pilot
redshift observations for 99 OPEG candidates with 19 < z' < 22 and found that
at least 78% (73/93) of the entire sample, or 95% (73/77) of these whose
redshifts were obtained are indeed lie between z=0.87 and 1.12 and the most of
their spectra show the continuum break and strong Ca H and K lines, indicating
that these objects are indeed dominated by the old stellar populations. We then
compare our results with the luminosity functions of the color- or the
morphologically-selected early type galaxies at z=0 taking the evolutionary
factor into account and found that the number density of old passive galaxies
with sim M_* magnitude at z~1 averaged over the SXDS area is 40-60% of the
equivalently red galaxies and 60-85% of the morphologically-selected E/S0
galaxies at z=0 depending on their luminosity evolution. It is revealed that
more than half, but not all, of the present-day early-type galaxies had already
been formed into quiescent passive galaxies at z=1.Comment: 28 pages, accepted for publication in Astrophysical Journal. The full
version of the paper including Fig.3 and Fig.4 (large size) in full
resolution is put at
http://optik2.mtk.nao.ac.jp/~yamada/astronomy/sxdsred.htm
The Subaru/XMM-Newton Deep Survey (SXDS) -VII. Clustering Segregation with Ultraviolet and Optical Luminosities of Lyman-Break Galaxies at z~3
We investigate clustering properties of Lyman-break galaxies (LBGs) at z~3
based on deep multi-waveband imaging data from optical to near-infrared
wavelengths in the Subaru/XMM-Newton Deep Field. The LBGs are selected by U-V
and V-z' colors in one contiguous area of 561 arcmin^2 down to z'=25.5. We
study the dependence of the clustering strength on rest-frame UV and optical
magnitudes, which can be indicators of star formation rate and stellar mass,
respectively. The correlation length is found to be a strong function of both
UV and optical magnitudes with brighter galaxies being more clustered than
faint ones in both cases. Furthermore, the correlation length is dependent on a
combination of UV and optical magnitudes in the sense that galaxies bright in
optical magnitude have large correlation lengths irrespective of UV magnitude,
while galaxies faint in optical magnitude have correlation lengths decreasing
with decreasing UV brightness. These results suggest that galaxies with large
stellar masses always belong to massive halos in which they can have various
star formation rates, while galaxies with small stellar masses reside in less
massive halos only if they have low star formation rates. There appears to be
an upper limit to the stellar mass and the star formation rate which is
determined by the mass of hosting dark halos.Comment: 16 pages, 15 figures, accepted for publication in Ap
Long-term persistence of X-ray-induced genomic instability in quiescent normal human diploid cells.
Ionizing radiation can induce genomic instability in the progeny of irradiated cells, as was demonstrated in various experimental systems. Most in vitro studies have utilized replicating cells, but it is not clear whether radiation-induced genomic instability persists in quiescent cells. Here we show the induction of X-ray-induced genomic instability in normal human diploid cells irradiated and maintained in a quiescent state for up to 24 months while cells were subcultured approximately once every 2-3 months. Every 12 months, a fraction of the irradiated cell population was stimulated to divide by culturing at a low density, and we found that these cells showed increased frequencies of phosphorylated ATM foci, decreased colony-forming ability, and increased frequency of chromosomal aberrations. No significant increases in ROS levels were detected in long-term cultured cells. These results suggest that there are ROS-independent mechanism(s) induced by radiation, which can generate persistent delayed effects in quiescent cells, and could ultimately contribute to carcinogenesis
Persistent Amplification of DNA Damage Signal Involved in Replicative Senescence of Normal Human Diploid Fibroblasts
Foci of phosphorylated histone H2AX and ATM are the surrogate markers of DNA double strand breaks. We previously reported that the residual foci increased their size after irradiation, which amplifies DNA damage signals. Here, we addressed whether amplification of DNA damage signal is involved in replicative senescence of normal human diploid fibroblasts. Large phosphorylated H2AX foci (>1.5 μm diameter) were specifically detected in presenescent cells. The frequency of cells with large foci was well correlated with that of cells positive for senescence-associated β-galactosidase staining. Hypoxic cell culture condition extended replicative life span of normal human fibroblast, and we found that the formation of large foci delayed in those cells. Our immuno-FISH analysis revealed that large foci partially localized at telomeres in senescent cells. Importantly, large foci of phosphorylated H2AX were always colocalized with phosphorylated ATM foci. Furthermore, Ser15-phosphorylated p53 showed colocalization with the large foci. Since the treatment of senescent cells with phosphoinositide 3-kinase inhibitor, wortmannin, suppressed p53 phosphorylation, it is suggested that amplification of DNA damage signaling sustains persistent activation of ATM-p53 pathway, which is essential for replicative senescence
Kaempulchraols PT: diterpenoids from the Kaempferia pulchra rhizomes collected in Myanmar
The isolation of the oily fraction obtained from the CHCl3-soluble extract of the rhizomes of Kaempferia pulchra (Zingiberaceae) afforded five new isopimarane diterpenoids, kaempulchraols P−T (1−5), along with two known analogues. The structures were elucidated using spectroscopic techniques, including 2D NMR spectroscopy
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