49 research outputs found
A Y-band look of the sky with 1-m class telescopes
Y -band is a broad passband that is centered at ~ 1 micron. It is becoming a
new, popular window for extragalactic study especially for observation of red
objects thanks to recent CCD technology developments. In order to better
understand the general characteristics of objects in Y -band, and to
investigate the promise of Y -band observations with small telescopes, we
carried out imaging observation of several extragalactic fields, brown dwarfs
and high redshift quasars with Y -band filter at the Mt. Lemmon Optical
Astronomy Observatory and the Maidanak observatory. From our observations, we
constrain the bright end of the galaxy and the stellar number counts in Y
-band. Also, we test the usefulness of high redshift quasar (z > 6) selection
via i-z-Y color-color diagram, to demonstrate that the i-z-Y color-color
diagram is effective for the selection of high redshift quasars even with a
conventional optical CCD camera installed at a 1-m class telescope.Comment: 12 pages, 6 figures, accepted for publication in JKA
Electrocatalytic arsenite oxidation in bicarbonate solutions combined with CO₂ reduction to formate
Sunlight-driven water-energy nexus technologies are receiving increasing attention. This study presents a hybrid electrochemical system that catalyzes the oxidation of As(III) to As(V) with a nanoparticulate TiO₂ electrocatalyst (Ti/Ir_(1-x)Ta_xO_y/TiO₂; denoted as an n-TEC) while simultaneously converting CO₂ to formate on a Bi electrode in aqueous bicarbonate solutions at circum-neutral pH. Linear sweep voltammograms of n-TEC exhibit a specific As(III) oxidation peak (E_(p,As)), at which the Faradaic efficiency (FE) of As(V) production is ∼100%. However, the application of a potential higher than the peak (E > E_(p,As)) leads to a significant decrease in the FE due to water oxidation. Upon the addition of chloride, the oxidation of water and chloride occur competitively, producing reactive chlorine species responsible for mediating the oxidation of As(III). The Bi electrodes synthesized via the electrodeposition of Bi³⁺ typically show high FEs of >80% for formate production in bicarbonate solution purged with CO₂. The addition of chloride significantly enhances the current while maintaining the FE. The n-TEC catalyst and Bi electrodes are paired in a single device equipped with a membrane, and significant effort is made to achieve the same FEs in both the anodic and cathodic reactions as in their half-reactions. Finally, the optimized n-TEC/Bi pair is coupled with a low-cost, commercially available photovoltaic (PV). Various technical factors that drive the overall reactions with the PV are considered, and maximum FEs of ∼95% are achieved for the production of both As(V) and formate
Camera for QUasars in EArly uNiverse (CQUEAN)
We describe the overall characteristics and the performance of an optical CCD
camera system, Camera for QUasars in EArly uNiverse (CQUEAN), which is being
used at the 2.1 m Otto Struve Telescope of the McDonald Observatory since 2010
August. CQUEAN was developed for follow-up imaging observations of red sources
such as high redshift quasar candidates (z >= 5), Gamma Ray Bursts, brown
dwarfs, and young stellar objects. For efficient observations of the red
objects, CQUEAN has a science camera with a deep depletion CCD chip which
boasts a higher quantum efficiency at 0.7 - 1.1 um than conventional CCD chips.
The camera was developed in a short time scale (~ one year), and has been
working reliably. By employing an auto-guiding system and a focal reducer to
enhance the field of view on the classical Cassegrain focus, we achieve a
stable guiding in 20 minute exposures, an imaging quality with FWHM >= 0.6"
over the whole field (4.8' * 4.8'), and a limiting magnitude of z = 23.4 AB mag
at 5-sigma with one hour total integration time.Comment: Accepted for publication in PASP. 26 pages including 5 tables and 24
figure
c-Jun N-terminal kinase activation has a prognostic implication and is negatively associated with FOXO1 activation in gastric cancer
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the Creative Commons license, and indicate if changes were made.Abstract
Background
Since the biological function of c-Jun N-terminal kinase (JNK) in gastric cancer remains unclear, we investigated the clinical significance of JNK activation and its association with FOXO1 activation.
Methods
Immunohistochemical tissue array analysis of 483 human gastric cancer specimens was performed, and the results of the immunostaining were quantified. The correlation between JNK activation (nuclear staining for pJNK) and clinicopathological features, the proliferation index, prognosis or FOXO1 inactivation (cytoplasmic staining for pFOXO1) was analyzed. The SNU-638 gastric cancer cell line was used for in vitro analysis.
Results
Nuclear staining of pJNK was found in 38 % of the gastric carcinomas and was higher in the early stages of pTNM (P < 0.001). pJNK staining negatively correlated with lymphatic invasion (P = 0.034) and positively correlated with intestinal type by Laurens classification (P = 0.037), Ki-67-labeling index (P < 0.001), cyclin D1 (P = 0.045), cyclin E (P < 0.001) and pFOXO1 (P < 0.001). JNK activation correlated with a longer patients survival (P =0.008) and patients with a JNK-active and FOXO1-inactive tumor had a higher survival rate than the remainder of the population (P = 0.004). In vitro analysis showed that JNK inhibition by SP600125 in SNU-638 cells decreased cyclin D1 protein expression and increased FOXO1 activation. Further, JNK inhibition markedly suppressed colony formation, which was partially restored by FOXO1 shRNA expression.
Conclusions
Our results indicate that JNK activation may serve as a valuable prognostic factor in gastric cancer, and that it is implicated in gastric tumorigenesis, at least in part, through FOXO1 inhibition
AKARI Observation of the North Ecliptic Pole (NEP) Supercluster at z = 0.087: mid-infrared view of transition galaxies
We present the mid-infrared (MIR) properties of galaxies within a
supercluster in the North Ecliptic Pole region at z?0.087 observed with the
AKARI satellite. We use data from the AKARI NEP-Wide (5.4 deg2) IR survey and
the CLusters of galaxies EVoLution studies (CLEVL) mission program. We show
that near-IR (3 {\mu}m)-mid- IR (11 {\mu}m) color can be used as an indicator
of the specific star formation rate and the presence of intermediate age
stellar populations. From the MIR observations, we find that red-sequence
galaxies consist not only of passively evolving red early-type galaxies, but
also of 1) "weak-SFG" (disk-dominated star-forming galaxies which have star
formation rates lower by \sim 4 \times than blue-cloud galaxies), and 2)
"intermediate- MXG" (bulge-dominated galaxies showing stronger MIR dust
emission than normal red early-type galaxies). Those two populations can be a
set of transition galaxies from blue, star-forming, late-type galaxies evolving
into red, quiescent, early-type ones. We find that the weak-SFG are predominant
at intermediate masses (1010M\odot < M\star < 1010.5M\odot) and are typically
found in local densities similar to the outskirts of galaxy clusters. As much
as 40% of the supercluster member galaxies in this mass range can be classified
as weak-SFGs, but their proportion decreases to < 10% at larger masses (M\star
> 1010.5 M\odot) at any galaxy density. The fraction of the intermediate-MXG
among red- sequence galaxies at 1010M\odot < M\star < 1011M\odot also decreases
as the density and mass increase. In particular, \sim42% of the red-sequence
galaxies with early-type morphologies are classified as intermediate-MXG at
intermediate densities. These results suggest that the star formation activity
is strongly dependent on the stellar mass, but that the morphological
transformation is mainly controlled by the environment.Comment: 46 pages, 25 figures, accepted for publication in Ap