1,106 research outputs found
A Census of Star-Forming Galaxies at z = 1-3 in the Subaru Deep Field
Several UV and near-infrared color selection methods have identified galaxies
at z = 1-3. Since each method suffers from selection biases, we have applied
three leading techniques (Lyman break, BX/BM, and BzK selection) simultaneously
in the Subaru Deep Field. This field has reliable ({\Delta}z/(1 + z) =
0.02--0.09) photometric redshifts for ~53,000 galaxies from 20 bands
(1500{\AA}--2.2{\mu}m). The BzK, LBG, and BX/BM samples suffer contamination
from z<1 interlopers of 6%, 8%, and 20%, respectively. Around the redshifts
where it is most sensitive (z~1.9 for star-forming BzK, z~1.8 for z~2 LBGs,
z~1.6 for BM, and z~2.3 for BX), each technique finds 60-80% of the census of
the three methods. In addition, each of the color techniques shares 75-96% of
its galaxies with another method, which is consistent with previous studies
that adopt identical criteria on magnitudes and colors. Combining the three
samples gives a comprehensive census that includes ~90% of z-phot = 1-3
galaxies, using standard magnitude limits similar to previous studies. In fact,
we find that among z = 1-2.5 galaxies in the color selection census, 81-90% of
them can be selected by just combining the BzK selection with one of the UV
techniques (z~2 LBG or BX and BM). The average galaxy stellar mass, reddening
and SFRs all decrease systematically from the sBzK population to the LBGs, and
to the BX/BMs. The combined color selections yield a total cosmic SFR density
of 0.18 0.03 M_sun yr^{-1} Mpc^{-3} for K_AB <= 24. We find that 65% of
the star formation is in galaxies with E(B-V) > 0.25 mag, even though they are
only one-fourth of the census by number.Comment: 26 pages, 30 figures, 9 tables, emulateapj format. Modified to match
the final ApJ versio
Utility of Whole Genome Sequencing in Assessing and Enhancing Partner Notification of Neisseria gonorrhoeae Infection
Background:
Gonorrhea is a sexually transmitted infection of global concern. We investigated whole genome sequencing (WGS) as a tool to measure and enhance partner notification (PN) in gonorrhea management. /
Methods:
Between May-November 2018, all N. gonorrhoeae isolated from patients attending Leeds Sexual Health, UK, underwent WGS. Reports listing sequences within 20 single nucleotide polymorphisms (SNPs) of study isolates within a database containing select isolates from April 1 2016 to November 15 2018 were issued to clinicians. The proportion of cases with a potential transmission partner identified by PN was determined from patient and PN data. WGS reports were reviewed to identify additional cases within ā¤6 SNPs and verified for PN concordance. /
Results:
380 isolates from 377 cases were successfully sequenced; 292 had traceable/contactable partners and 69 (18%) had a potential transmission partner identified by PN. Concordant PN and WGS links were identified in 47 partner pairs. Of 308 cases with no transmission partner by PN, 185 (60%) had a case within ā¤6 SNPs; examination of these casesā PN data identified seven partner pairs with previously unrecognized PN link, giving a total of 54 pairs; all had ā¤4 SNP differences. WGS clusters confirmed gaps in partner finding, at individual and group levels. Despite the clinic providing sexual health services to the whole city, 35 cases with multiple partners had no genetically related case, suggesting multiple undiagnosed infections. /
Conclusions:
WGS could improve gonorrhea PN and control by identifying new links and clusters with significant gaps in partner finding
Star Formation Rates and Metallicities of K-selected Star Forming Galaxies at z~2
We present spectroscopy of 15 star-forming BzK galaxies (sBzKs) with K(AB)<23
in the Subaru Deep Field, for which Halpha and some other emission lines are
detected in 0.9 to 2.3 micron spectra with a resolution of R=500. Using Halpha
luminosities, we obtain star formation rates (SFRs), and then specific SFRs
(SSFRs) dividing SFRs by stellar masses, which are derived from SED fitting to
BVRi'z'K photometry. It is found that sBzKs with higher stellar masses have
larger SFRs. A negative correlation is seen between stellar mass and SSFR,
which is consistent with the previous results for z~2 galaxies. This implies
that a larger growth of stellar mass occurs in less massive galaxies. In
addition, gas-phase oxygen abundances, 12+log(O/H), are derived from the ratio
of NII(lambda 6584) to Halpha using the N2 index method. We have found a
correlation between stellar mass and oxygen abundance in the sense that more
massive sBzKs tend to be more metal rich, which is qualitatively consistent
with the relation for UV-selected z~2 galaxies. However, the metallicity of the
sBzKs is ~0.2 dex higher than that of UV-selected galaxies with similar stellar
masses, which is significant considering the small uncertainties. The sBzKs in
our sample have redder R-K colors than the UV-selected galaxies. This galaxy
color-dependence in the oxygen abundance may be caused by older or dustier
galaxies having higher metallicities at z~2.Comment: 20 pages, 13 figures, 2 tables, accepted for publication in The
Astrophysical Journa
Wnt2 secreted by tumour fibroblasts promotes tumour progression in oesophageal cancer by activation of the Wnt/Ī²-catenin signalling pathway
Objectives: Interaction between neoplastic and stromal cells plays an important role in tumour progression. It was recently found that WNT2 was frequently overexpressed in fibroblasts isolated from tumour tissue tumour fibroblasts (TF) compared with fibroblasts from non-tumour tissue normal fibroblasts in oesophageal squamous cell carcinoma (OSCC). This study aimed to investigate the effect of TF-secreted Wnt2 in OSCC development via the tumour - stroma interaction. Methods: Quantitative PCR, western blotting, immunohistochemistry and immunofluorescence were used to study the expression pattern of Wnt2 and its effect on the Wnt/Ī²-catenin pathway. A Wnt2-secreting system was established in Chinese hamster ovary cells and its conditioned medium was used to study the role of Wnt2 in cell proliferation and invasion. Results: Expression of Wnt2 could only be detected in TF but not in OSCC cancer cell lines. In OSCC tissues, Wnt2 (+) cells were mainly detected in the boundary between stroma and tumour tissue or scattered within tumour tissue. In this study, Wnt2-positive OSCC was defined when five or more Wnt2(+) cells were observed in 2003X microscopy field. Interestingly, Wnt2-positive OSCC (22/51 cases) was significantly associated with lymph node metastases (p=0.001), advanced TNM stage (p=0.001) and disease-specific survival (p<0.0001). Functional study demonstrated that secreted Wnt2 could promote oesophageal cancer cell growth by activating the Wnt/Ī²-catenin signalling pathway and subsequently upregulated cyclin D1 and c-myc expression. Further study found that Wnt2 could enhance cell motility and invasiveness by inducing epithelial-mesenchymal transition. Conclusions: TF-secreted Wnt2 acts as a growth and invasion-promoting factor through activating the canonical Wnt/Ī²-catenin signalling pathway in oesophageal cancer cells.published_or_final_versio
The Bayes factor and its implementation in JASP: A practical primer
Statistical inference plays a critical role in modern scientific research, however, the dominant method for statistical inference in science, null hypothesis significance testing (NHST), is often misunderstood and misused, which leads to unreproducible findings. To address this issue, researchers propose to adopt the Bayes factor as an alternative to NHST. The Bayes factor is a principled Bayesian tool for model selection and hypothesis testing, and can be interpreted as the strength for both the null hypothesis H0 and the alternative hypothesis H1 based on the current data. Compared to NHST, the Bayes factor has the following advantages: it quantifies the evidence that the data provide for both the H0 and the H1, it is not āviolently biasedā against H0, it allows one to monitor the evidence as the data accumulate, and it does not depend on sampling plans. Importantly, the recently developed open software JASP makes the calculation of Bayes factor accessible for most researchers in psychology, as we demonstrated for the t-test. Given these advantages, adopting the Bayes factor will improve psychological researchersā statistical inferences. Nevertheless, to make the analysis more reproducible, researchers should keep their data analysis transparent and open
A star-bursting proto-cluster in making associated to a radio galaxy at z=2.53 discovered by H_alpha imaging
We report a discovery of a proto-cluster in vigorous assembly and hosting
strong star forming activities, associated to a radio galaxy USS 1558-003 at
z=2.53, as traced by a wide-field narrow-band H_alpha imaging with MOIRCS on
Subaru Telescope. We find 68 H_alpha emitters with dust-uncorrected SFRs down
to 8.6 Msun/yr. Their spatial distribution indicates that there are three
prominent clumps of H_alpha emitters, one surrounding the radio galaxy and
another located at ~1.5 Mpc away to the south-west, and the other located in
between the two. These contiguous three systems are very likely to merge
together in the near future and may grow to a single more massive cluster at
later times. Whilst most H_alpha emitters reside in the "blue cloud" on the
color--magnitude diagram, some emitters have very red colors with
J-Ks>1.38(AB). Interestingly, such red H_alpha emitters are located towards the
faint end of the red sequence, and they tend to be located in the high density
clumps. We do not see any statistically significant difference in the
distributions of individual star formation rates or stellar masses of the
H_alpha emitters between the dense clumps and the other regions, suggesting
that this is one of the notable sites where the progenitors of massive galaxies
in the present-day clusters were in their vigorous formation phase. Finally, we
find that H_alpha emission of the radio galaxy is fairly extended spatially
over ~4.5 arcsec. However it is not as widespread as its Lya halo, meaning that
the Lya emission is indeed severely extended by resonant scattering.Comment: 14 pages, 11 figures, 3 tables, accepted for publication in Ap
Structural and infrared absorption properties of self-organized InGaAs GaAs quantum dots multilayers
Self-organized InGaAs/GaAs quantum dots (QDs) stacked multilayers have been prepared by solid source molecular beam epitaxy. Cross-sectional transmission electron microscopy shows that the InGaAs QDs are nearly perfectly vertically aligned in the growth direction [100]. The filtering effect on the QDs distribution is found to be the dominant mechanism leading to vertical alignment and a highly uniform size distribution. Moreover, we observe a distinct infrared absorption from the sample in the range of 8.6-10.7 mu m. This indicates the potential of QDs multilayer structure for use as infrared photodetector
High star formation activity in the central region of a distant cluster at z=1.46
We present an unbiased deep [OII] emission survey of a cluster XMMXCS
J2215.9-1738 at z=1.46, the most distant cluster to date with a detection of
extended X-ray emission. With wide-field optical and near-infrared cameras
(Suprime-Cam and MOIRCS, respectively) on Subaru telescope, we performed deep
imaging with a narrow-band filter NB912 (lambda_c=9139A, Delta_lambda=134A) as
well as broad-band filters (B, z', J and Ks). From the photometric catalogues,
we have identified 44 [OII] emitters in the cluster central region of 6'x6'
down to a dust-free star formation rate of 2.6 Msun/yr (3 sigma).
Interestingly, it is found that there are many [OII] emitters even in the
central high density region. In fact, the fraction of [OII] emitters to the
cluster members as well as their star formation rates and equivalent widths
stay almost constant with decreasing cluster-centric distance up to the cluster
core. Unlike clusters at lower redshifts (z<1) where star formation activity is
mostly quenched in their central regions, this higher redshift 2215 cluster
shows its high star formation activity even at its centre, suggesting that we
are beginning to enter the formation epoch of some galaxies in the cluster core
eventually. Moreover, we find a deficit of galaxies on the red sequence at
magnitudes fainter than ~M*+0.5 on the colour-magnitude diagram. This break
magnitude is brighter than that of lower redshift clusters, and it is likely
that we are seeing the formation phase of more massive red galaxies in the
cluster core at z~1. These results may indicate inside-out and down-sizing
propagation of star formation activity in the course of cluster evolution.Comment: 12 pages, 9 figures, 1 table, accepted for publication in MNRA
Properties of star-forming galaxies in a cluster and its surrounding structure at z=1.46
We conduct a narrow-band imaging survey of [OII] emitters over a 32'x23' area
in and around the XMMXCS J2215.9-1738 cluster at z=1.46 with
Subaru/Suprime-Cam, and select 380 [OII] emitting galaxies down to 1.4E-17
erg/s/cm2. Among them, 16 [OII] emitters in the cluster central region are
confirmed by NIR spectroscopy with Subaru/MOIRCS. We find that [OII] emitters
are distributed along filamentary large-scale structures around the cluster.
The z'-K vs K colour-magnitude diagram shows that a significantly higher
fraction of [OII] emitters is seen on the red sequence in the cluster core than
in other environments we define in this paper. It is likely that these red
galaxies are nearly passively evolving galaxies which host [OII] emitting AGNs,
rather than dust-reddened star-forming galaxies. We argue therefore that AGN
feedback may be one of the critical processes to quench star formation in
massive galaxies in high density regions. We also find that the cluster has
experienced high star formation activities at rates comparable to that in the
field at z=1.46. In addition, a mass-metallicity relation exists in the cluster
at z=1.46, which is similar to that of star-forming galaxies in the field at
z~2. These results all suggest that at z~1.5 star formation activity in the
cluster core becomes as high as those in low density environments and there is
apparently not yet a strong environmental dependence, except for the red
emitters.Comment: 19 pages, 17 figures, 4 tables, accepted for publication in MNRA
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