35 research outputs found
Are Two z~6 Quasars Gravitationally Lensed ?
Several high-z (z > 5.7) quasars have been found in the course of Sloan
Digital Sky Survey. The presence of such very high-z quasars is expected to
give constraints on early structure formation. On one hand, it is suggested
that these most luminous objects at high redshift are biased toward the highly
magnified objects by gravitational lensing. To clarify the effect of
gravitational lensing on the high-z quasars, we began the imaging survey of
intervening lensing galaxies. Indeed our previous optical image showed that
SDSSp J104433.04+012502.2 at z=5.74 is gravitationally magnified by a factor 2.
In this paper, we report our new optical imaging of other two high-z quasars,
SDSSp J103027.10+052455.0 at z=6.28 and SDSSp J130608.26+035626.3 at z=5.99.
Since we find neither intervening galaxy nor counter image with i^{\prime} <
25.4-25.8 around each quasar, we conclude that they are not strongly magnified
regardless that a lens galaxy is dusty.Comment: 10 pages, 8 figures, Accepted for PAS
SDSSp J104433.04012502.2 at is Gravitationally Magnified by an Intervening Galaxy
During the course of our optical deep survey program on L emitters at
in the sky area surrounding the quasar SDSSp
J104433.04012502.2 at , we found that a faint galaxy with (AB)
is located at \timeform{1".9} southwest of the quasar. Its
broad-band color properties from to suggest that the galaxy is
located at a redshift of -- 2.5. This is consistent with no strong
emission line in our optical spectroscopy. Since the counter image of the
quasar cannot be seen in our deep optical images, the magnification factor
seems not to be very high. Our modest estimate is that this quasar is
gravitationally magnified by a factor of 2.Comment: 11 pages, 5 figures, PASJ, in pres
The Discovery of a Very Narrow-Line Star Forming Obat a Redshift of 5.66ject
We report on the discovery of a very narrow-line star forming object beyond
redshift of 5. Using the prime-focus camera, Suprime-Cam, on the 8.2 m Subaru
telescope together with a narrow-passband filter centered at
= 8150 \AA with passband of = 120 \AA, we have obtained a very
deep image of the field surrounding the quasar SDSSp J104433.04012502.2 at a
redshift of 5.74. Comparing this image with optical broad-band images, we have
found an object with a very strong emission line. Our follow-up optical
spectroscopy has revealed that this source is at a redshift of
, forming stars at a rate
yr. Remarkably, the velocity dispersion of Ly-emitting gas is
only 22 km s. Since a blue half of the Ly emission could be
absorbed by neutral hydrogen gas, perhaps in the system, a modest estimate of
the velocity dispersion may be 44 km s. Together with a linear
size of 7.7 kpc, we estimate a lower limit of the dynamical mass
of this object to be . It is thus suggested that
LAE J10440123 is a star-forming dwarf galaxy (i.e., a subgalactic object or
a building block) beyond redshift 5 although we cannot exclude a possibility
that most Ly emission is absorbed by the red damping wing of neutral
intergalactic matter.Comment: 6 pages, 2 figures. ApJ Letters, in pres
The Subaru Deep Field Project: Lyman Emitters at Redshift of 6.6
We present new results of a deep optical imaging survey using a narrowband
filter () centered at 9196 \AA ~ together with , ,
, , and broadband filters in the sky area of the Subaru
Deep Field which has been promoted as one of legacy programs of the 8.2m Subaru
Telescope. We obtained a photometric sample of 58 Ly emitter candidates
at 6.5 -- 6.6 among strong -excess () objects together with a color criterion of . We then obtained optical spectra of 20 objects in our -excess
sample and identified at least nine Ly emitters at -- 6.6
including the two emitters reported by Kodaira et al. (2003). Since our
Ly emitter candidates are free from strong amplification of
gravitational lensing, we are able to discuss their observational properties
from a statistical point of view. Based on these new results, we obtain a lower
limit of the star formation rate density of yr Mpc at , being
consistent with our previous estimate. We discuss the nature of star-formation
activity in galaxies beyond .Comment: 49 pages, 16 figures, PASJ, Vol. 57, No. 1, in pres
Florbetaben PET imaging to detect amyloid beta plaques in Alzheimer's disease: Phase 3 study
AbstractBackgroundEvaluation of brain β-amyloid by positron emission tomography (PET) imaging can assist in the diagnosis of Alzheimer disease (AD) and other dementias.MethodsOpen-label, nonrandomized, multicenter, phase 3 study to validate the 18F-labeled β-amyloid tracer florbetaben by comparing in vivo PET imaging with post-mortem histopathology.ResultsBrain images and tissue from 74 deceased subjects (of 216 trial participants) were analyzed. Forty-six of 47 neuritic β-amyloid-positive cases were read as PET positive, and 24 of 27 neuritic β-amyloid plaque-negative cases were read as PET negative (sensitivity 97.9% [95% confidence interval or CI 93.8–100%], specificity 88.9% [95% CI 77.0–100%]). In a subgroup, a regional tissue-scan matched analysis was performed. In areas known to strongly accumulate β-amyloid plaques, sensitivity and specificity were 82% to 90%, and 86% to 95%, respectively.ConclusionsFlorbetaben PET shows high sensitivity and specificity for the detection of histopathology-confirmed neuritic β-amyloid plaques and may thus be a valuable adjunct to clinical diagnosis, particularly for the exclusion of AD.Trial registrationClinicalTrials.gov NCT01020838
Clustering of Lyman Break Galaxies at z=4 and 5 in The Subaru Deep Field: Luminosity Dependence of The Correlation Function Slope
We explored the clustering properties of Lyman Break Galaxies (LBGs) at z=4
and 5 with an angular two-point correlation function on the basis of the very
deep and wide Subaru Deep Field data. We found an apparent dependence of the
correlation function slope on UV luminosity for LBGs at both z=4 and 5. More
luminous LBGs have a steeper correlation function. To compare these
observational results, we constructed numerical mock LBG catalogs based on a
semianalytic model of hierarchical clustering combined with high-resolution
N-body simulation, carefully mimicking the observational selection effects. The
luminosity functions for LBGs predicted by this mock catalog were found to be
almost consistent with the observation. Moreover, the overall correlation
functions of LBGs were reproduced reasonably well. The observed dependence of
the clustering on UV luminosity was not reproduced by the model, unless
subsamples of distinct halo mass were considered. That is, LBGs belonging to
more massive dark haloes had steeper and larger-amplitude correlation
functions. With this model, we found that LBG multiplicity in massive dark
halos amplifies the clustering strength at small scales, which steepens the
slope of the correlation function. The hierarchical clustering model could
therefore be reconciled with the observed luminosity-dependence of the angular
correlation function, if there is a tight correlation between UV luminosity and
halo mass. Our finding that the slope of the correlation function depends on
luminosity could be an indication that massive dark halos hosted multiple
bright LBGs (abridged).Comment: 16 pages, 17 figures, Accepted for publication in ApJ, Full
resolution version is available at
http://zone.mtk.nao.ac.jp/~kashik/sdf/acf/sdf_lbgacf.pd
DOCK2 is involved in the host genetics and biology of severe COVID-19
「コロナ制圧タスクフォース」COVID-19疾患感受性遺伝子DOCK2の重症化機序を解明 --アジア最大のバイオレポジトリーでCOVID-19の治療標的を発見--. 京都大学プレスリリース. 2022-08-10.Identifying the host genetic factors underlying severe COVID-19 is an emerging challenge. Here we conducted a genome-wide association study (GWAS) involving 2, 393 cases of COVID-19 in a cohort of Japanese individuals collected during the initial waves of the pandemic, with 3, 289 unaffected controls. We identified a variant on chromosome 5 at 5q35 (rs60200309-A), close to the dedicator of cytokinesis 2 gene (DOCK2), which was associated with severe COVID-19 in patients less than 65 years of age. This risk allele was prevalent in East Asian individuals but rare in Europeans, highlighting the value of genome-wide association studies in non-European populations. RNA-sequencing analysis of 473 bulk peripheral blood samples identified decreased expression of DOCK2 associated with the risk allele in these younger patients. DOCK2 expression was suppressed in patients with severe cases of COVID-19. Single-cell RNA-sequencing analysis (n = 61 individuals) identified cell-type-specific downregulation of DOCK2 and a COVID-19-specific decreasing effect of the risk allele on DOCK2 expression in non-classical monocytes. Immunohistochemistry of lung specimens from patients with severe COVID-19 pneumonia showed suppressed DOCK2 expression. Moreover, inhibition of DOCK2 function with CPYPP increased the severity of pneumonia in a Syrian hamster model of SARS-CoV-2 infection, characterized by weight loss, lung oedema, enhanced viral loads, impaired macrophage recruitment and dysregulated type I interferon responses. We conclude that DOCK2 has an important role in the host immune response to SARS-CoV-2 infection and the development of severe COVID-19, and could be further explored as a potential biomarker and/or therapeutic target