141 research outputs found
Large Faraday effect of borate glasses with high Tb³⁺ content prepared by containerless processing
Borate glasses containing a large amount of Tb³⁺ ions have been prepared by containerless processing. The content of Tb₂O₃ reached 60 mol%. The glass bearing the highest content of Tb³⁺ ions showed a large Faraday effect; the Verdet constant was 234 rad/T m. Annealing of the glasses in H₂/N₂ atmosphere resulted in a low optical absorption coefficient, leading to an extremely large magneto-optical figure of merit that was ∼1.7 times higher than that of Tb₃Ga₅O₁₂ single crystal
Astrometry of Star Forming Region IRAS 05137+3919 in the far outer Galaxy
We present the results of astrometric observations with VERA toward the H2O
maser sources in IRAS 05137+3919, which is thought to be located in the far
outer Galaxy. We have derived the parallax of \pi = 0.086 +/- 0.027 mas, which
corresponds to the source distance of D=11.6+5.3-2.8 kpc. Although the parallax
measurement is only 3-sigma level and thus the distance uncertainty is
considerably large, we can strongly constrain the minimum distance to this
source, locating the source at the distance from the Sun greater than 8.3 kpc
(or 16.7 kpc from the Galaxy's center) at 90% confidence level. Our results
provide an astrometric confirmation that this source is located in the far
outer Galaxy beyond 15 kpc from the Galaxy center, indicating that IRAS
05137+3919 is one of the most distant star-forming regions from the Galaxy
center.Comment: 7 pages, 2 figures, to appear in PASJ vol 63. No1 (VERA special
issue
Annual Parallax Measurements of an Infrared Dark Cloud MSXDC G034.43+00.24 with VERA
We have measured the annual parallax of the H2O maser source associated with
an infrared dark cloud MSXDC G034.43+00.24 from the observations with VERA
(VLBI Exploration of Radio Astrometry). The parallax is 0.643 +/- 0.049 mas,
corresponding to the distance of 1.56 +0.12/-0.11 kpc. This value is less than
the half of the previous kinematic distance of 3.7 kpc. We revise the core mass
estimates of MSXDC G034.43+00.24, based on virial masses, LTE masses and dust
masses and show that the core masses decrease from the previous estimations of
~1000 Mo to hundreds of Mo. The spectral type derived from the luminosity also
changes from O9.5 to B1 in the case of MM1. This spectral type is still
consistent with that of the massive star. The radial velocity derived from the
flat rotation model is smaller than the observed velocity, which corresponds to
the peculiar motion of ~40 km/s in the line-of-sight direction.Comment: 14 pages, 11 figures, accepted to PASJ (vol. 63, No. 3
Resveratrol inhibits development of colorectal adenoma via suppression of LEF1; comprehensive analysis with connectivity map
Although many chemopreventive studies on colorectal tumors have been reported, no effective and safe preventive agent is currently available. We searched for candidate preventive compounds against colorectal tumor comprehensively from United States Food and Drug Administration (FDA)-approved compounds by using connectivity map (CMAP) analysis coupled with in vitro screening with colorectal adenoma (CRA) patient-derived organoids (PDOs). We generated CRA-specific gene signatures based on the DNA microarray analysis of CRA and normal epithelial specimens, applied them to CMAP analysis with 1309 FDA-approved compounds, and identified 121 candidate compounds that should cancel the gene signatures. We narrowed them down to 15 compounds, and evaluated their inhibitory effects on the growth of CRA-PDOs in vitro. We finally identified resveratrol, one of the polyphenolic phytochemicals, as a compound showing the strongest inhibitory effect on the growth of CRA-PDOs compared with normal epithelial PDOs. When resveratrol was administered to ApcMin/+ mice at 15 or 30 mg/kg, the number of polyps (adenomas) was significantly reduced in both groups compared with control mice. Similarly, the number of polyps (adenomas) was significantly reduced in azoxymethane-injected rats treated with 10 or 100 mg/resveratrol compared with control rats. Microarray analysis of adenomas from resveratrol-treated rats revealed the highest change (downregulation) in expression of LEF1, a key molecule in the Wnt signaling pathway. Treatment with resveratrol significantly downregulated the Wnt-target gene (MYC) in CRA-PDOs. Our data demonstrated that resveratrol can be the most effective compound for chemoprevention of colorectal tumors, the efficacy of which is mediated through suppression of LEF1 expression in the Wnt signaling pathway
Fundamental Parameters of the Milky Way Galaxy Based on VLBI astrometry
We present analyses to determine the fundamental parameters of the Galaxy
based on VLBI astrometry of 52 Galactic maser sources obtained with VERA, VLBA
and EVN. We model the Galaxy's structure with a set of parameters including the
Galaxy center distance R_0, the angular rotation velocity at the LSR Omega_0,
mean peculiar motion of the sources with respect to Galactic rotation (U_src,
V_src, W_src), rotation-curve shape index, and the V component of the Solar
peculiar motions V_sun. Based on a Markov chain Monte Carlo method, we find
that the Galaxy center distance is constrained at a 5% level to be R_0 = 8.05
+/- 0.45 kpc, where the error bar includes both statistical and systematic
errors. We also find that the two components of the source peculiar motion
U_src and W_src are fairly small compared to the Galactic rotation velocity,
being U_src = 1.0 +/- 1.5 km/s and W_src = -1.4 +/- 1.2 km/s. Also, the
rotation curve shape is found to be basically flat between Galacto-centric
radii of 4 and 13 kpc. On the other hand, we find a linear relation between
V_src and V_sun as V_src = V_sun -19 (+/- 2) km/s, suggesting that the value of
V_src is fully dependent on the adopted value of V_sun. Regarding the rotation
speed in the vicinity of the Sun, we also find a strong correlation between
Omega_0 and V_sun. We find that the angular velocity of the Sun, Omega_sun,
which is defined as Omega_sun = Omega_0 + V_sun/R_0, can be well constrained
with the best estimate of Omega_sun = 31.09 +/- 0.78 km/s/kpc. This corresponds
to Theta_0 = 238 +/- 14 km/s if one adopts the above value of R_0 and recent
determination of V_sun ~ 12 km/s.Comment: 14 pages, 6 figures, PASJ in pres
Distance to Orion KL Measured with VERA
We present the initial results of multi-epoch VLBI observations of the 22 GHz
H2O masers in the Orion KL region with VERA (VLBI Exploration of Radio
Astrometry). With the VERA dual-beam receiving system, we have carried out
phase-referencing VLBI astrometry and successfully detected an annual parallax
of Orion KL to be 2.29+/-0.10 mas, corresponding to the distance of 437+/-19 pc
from the Sun. The distance to Orion KL is determined for the first time with
the annual parallax method in these observations. Although this value is
consistent with that of the previously reported, 480+/-80 pc, which is
estimated from the statistical parallax method using proper motions and radial
velocities of the H2O maser features, our new results provide the much more
accurate value with an uncertainty of only 4%. In addition to the annual
parallax, we have detected an absolute proper motion of the maser feature,
suggesting an outflow motion powered by the radio source I along with the
systematic motion of source I itself.Comment: 7 pages, 3 figures. PASJ, in press (Vol. 59, No. 5, October 25, 2007
issue
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