152 research outputs found
The total rest-frame UV luminosity function from : A simultaneous study of AGN and galaxies from
We present measurements of the rest-frame ultraviolet luminosity function (UV
LF) at redshifts , and , using 96894, 38655 and 7571 sources
respectively to map the transition between AGN and galaxy-dominated ultraviolet
emission shortly after the epoch of reionization. Sources are selected using a
comprehensive photometric redshift approach, using \ds\, of deep
extragalactic legacy fields covered by both HSC and VISTA. The use of template
fitting spanning a wavelength range of achieves
per cent completeness, much higher than classical colour-colour
cut methodology. The measured LF encompasses at
. This is further extended to using
complementary results from other studies, allowing for the simultaneous fitting
of the combined AGN and galaxy LF. We find that there are fewer UV luminous
galaxies () at than , indicative of an onset
of widespread quenching alongside dust obscuration, and that the evolution of
the AGN LF is much more rapid than the galaxy LF, with their number density
rising by around 2 orders of magnitude from . We also find that it
remains difficult to determine if a double power law (DPL) functional form is
preferred over the Schechter function to describe the galaxy UV LF with
photometric data alone. Estimating the Hydrogen ionizing photon budget from our
UV LFs, we find that AGN can contribute to, but cannot solely maintain, the
reionization of the Universe at . However, the rapidly evolving AGN LF
strongly disfavours a significant contribution within the EoR.Comment: 20 pages, 5 Tables, 12 Figures, Submitted to MNRA
The bright end of the galaxy luminosity function at from the VISTA VIDEO survey
We have conducted a search for Lyman break galaxies over 8.2
square degrees of near-infrared imaging from the VISTA Deep Extragalactic
Observations (VIDEO) survey in the XMM-Newton - Large Scale Structure (XMM-LSS)
and the Extended Chandra Deep Field South (ECDF-S) fields. Candidate galaxies
were selected from a full photometric redshift analysis down to a depth
of 25.3 (), utilizing deep auxiliary optical and Spitzer/IRAC data to
remove brown dwarf and red interloper galaxy contaminants. Our final sample
consists of 28 candidate galaxies at with . We derive stellar masses of for the sample, suggesting that these
candidates represent some of the most massive galaxies known at this epoch. We
measure the rest-frame UV luminosity function (LF) at , confirming
previous findings of a gradual decline in number density at the bright-end
() that is well described by a double-power law (DPL).
We show that quasar contamination in this magnitude range is expected to be
minimal, in contrast to conclusions from recent pure-parallel Hubble studies.
Our results are up to a factor of ten lower than previous determinations from
optical-only ground-based studies at . We find that
the inclusion of photometry is vital for removing brown-dwarf
contaminants, and samples based on red-optical data alone could be
highly contaminated ( per cent). In comparison with other robust samples, our results further support little evolution in the very
bright-end of the rest-frame UV LF from , potentially signalling a
lack of mass quenching and/or dust obscuration in the most massive galaxies in
the first Gyr.Comment: 15 pages, 6 figures, 5 tables (plus additional figures/tables in
Appendix). Submitted to MNRA
MIGHTEE: multi-wavelength counterparts in the COSMOS field
In this paper, we combine the Early Science radio continuum data from the MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Survey, with optical and near-infrared data and release the cross-matched catalogues. The radio data used in this work covers 0.86 deg2 of the COSMOS field, reaches a thermal noise of 1.7 μJy beam−1 and contains 6102 radio components. We visually inspect and cross-match the radio sample with optical and near-infrared data from the Hyper Suprime-Cam (HSC) and UltraVISTA surveys. This allows the properties of active galactic nuclei and star-forming populations of galaxies to be probed out to z ≈ 5. Additionally, we use the likelihood ratio method to automatically cross-match the radio and optical catalogues and compare this to the visually cross-matched catalogue. We find that 94 per cent of our radio source catalogue can be matched with this method, with a reliability of 95 per cent. We proceed to show that visual classification will still remain an essential process for the cross-matching of complex and extended radio sources. In the near future, the MIGHTEE survey will be expanded in area to cover a total of ∼20 deg2; thus the combination of automated and visual identification will be critical. We compare the redshift distribution of SFG and AGN to the SKADS and T-RECS simulations and find more AGN than predicted at z ∼ 1
Ataxin-1 Fusion Partners Alter PolyQ Lethality and Aggregation
Intranuclear inclusion bodies (IBs) are the histopathologic markers of multiple protein folding diseases. IB formation has been extensively studied using fluorescent fusion products of pathogenic polyglutamine (polyQ) expressing proteins. These studies have been informative in determining the cellular targets of expanded polyQ protein as well as the methods by which cells rid themselves of IBs. The experimental thrust has been to intervene in the process of polyQ aggregation in an attempt to alleviate cytotoxicity. However new data argues against the notion that polyQ aggregation and cytotoxicity are inextricably linked processes. We reasoned that changing the protein context of a disease causing polyQ protein could accelerate its precipitation as an IB, potentially reducing its cytotoxicity. Our experimental strategy simply exploited the fact that conjoined proteins influence each others folding and aggregation properties. We fused a full-length pathogenic ataxin-1 construct to fluorescent tags (GFP and DsRed1-E5) that exist at different oligomeric states. The spectral properties of the DsRed1-E5-ataxin-1 transfectants had the additional advantage of allowing us to correlate fluorochrome maturation with cytotoxicity. Each fusion protein expressed a distinct cytotoxicity and IB morphology. Flow cytometric analyses of transfectants expressing the greatest fluorescent signals revealed that the DsRed1-E5-ataxin-1 fusion was more toxic than GFP fused ataxin-1 (31.8±4.5% cell death versus 12.85±3%), although co-transfection with the GFP fusion inhibited maturation of the DsRed1-E5 fluorochrome and diminished the toxicity of the DsRed1-E5-ataxin-1 fusion. These data show that polyQ driven aggregation can be influenced by fusion partners to generate species with different toxic properties and provide new opportunities to study IB aggregation, maturation and lethality
The Arg233Lys AQP0 Mutation Disturbs Aquaporin0-Calmodulin Interaction Causing Polymorphic Congenital Cataract
Calmodulin (CaM) directly interacts with the aquaporin 0 (AQP0) C-terminus in a calcium dependent manner to regulate the water permeability of AQP0. We previously identified a missense mutation (p.R233K) in the putative CaM binding domain of AQP0 C-terminus in a congenital cataract family. This study was aimed at exploring the potential pathogenesis of this mutation causative of cataract and mainly identifying how it influenced the binding of AQP0 to CaM. Wild type and R233K mutant AQP0 with EGFP-tag were transfected separately into Hela cells to determine the expression and subcellular localizations. The co-immunoprecipitation (CoIP) assay was used to detect the interaction between AQP0 and CaM. AQP0 C-terminus peptides were synthesized with and without R233K, and the binding abilities of these peptides to CaM were assessed using a fluorescence binding assay. Localizations of wild type and R233K mutant AQP0 were determined from EGFP fluorescence, and the chimeric proteins were both localized abundantly in the plasma membrane. Protein expression levels of the culture cells showed no significant difference between them. The results from CoIP assay implied that R233K mutant presented more weakly in association with CaM than wild type AQP0. The AQP0 C-terminal mutant peptide was found to have 2.5-fold lower binding affinity to CaM than wild type peptide. These results suggested that R233K mutation did not affect the expression, location and trafficking of the protein but did influence the interaction between AQP0 and CaM. The binding affinity of AQP0 C-terminus to CaM was significantly reduced. Due to lack of the modulation of the Ca2+-calmodulin complex, the water permeability of AQP0 was subsequently augmented, which might lead to the development of this cataract
Erratum to: Is Sensory Loss an Understudied Risk Factor for Frailty? A Systematic Review and Meta-analysis
In the article “Is Sensory Loss an Understudied Risk Factor for Frailty? A Systematic Review and Meta-analysis,” an author was missing. Ana Maseda should be listed as the 11th author. The correct author list is: Benjamin Kye Jyn Tan, Ryan Eyn Kidd Man, Alfred Tau Liang Gan, Eva K Fenwick, Varshini Varadaraj, Bonnielin K Swenor, Preeti Gupta, Tien Yin Wong, Caterina Trevisan, Laura Lorenzo-López, Ana Maseda, José Carlos Millán-Calenti, Carla Helena Augustin Schwanke, Ann Liljas, Soham Al Snih, Yasuharu Tokuda, Ecosse Luc Lamoureux. This error has been corrected
The discovery of a z=0.7092 OH megamaser with the MIGHTEE survey
We present the discovery of the most distant OH megamaser to be observed in the main lines, using data from the MeerKAT
International Giga-Hertz Tiered Extragalactic Exploration (MIGHTEE) survey. At a newly measured redshift of = 0.7092, the
system has strong emission in both the 1665 MHz ( ≈ 2500 L⊙) and 1667 MHz ( ≈ 4.5×104 L⊙) transitions, with both narrow
and broad components. We interpret the broad line as a high-velocity-dispersion component of the 1667 MHz transition, with
velocity ∼ 330 km s−1 with respect to the systemic velocity. The host galaxy has a stellar mass of ★ = 2.95 × 1010 M⊙ and a
star-formation rate of SFR = 371 M⊙ yr−1
, placing it ∼ 1.5 dex above the main sequence for star-forming galaxies at this redshift,
and can be classified as an ultra-luminous infrared galaxy. Alongside the optical imaging data, which exhibits evidence for a tidal
tail, this suggests that the OH megamaser arises from a system that is currently undergoing a merger, which is stimulating star
formation and providing the necessary conditions for pumping the OH molecule to saturation. The OHM is likely to be lensed,
with a magnification factor of ∼ 2.5, and perhaps more if the maser emitting region is compact and suitably offset relative to
the centroid of its host galaxy’s optical light. This discovery demonstrates that spectral line mapping with the new generation of
radio interferometers may provide important information on the cosmic merger history of galaxies
The discovery of a z=0.7092 OH megamaser with the MIGHTEE survey
We present the discovery of the most distant OH megamaser to be observed in
the main lines, using data from the MeerKAT International Giga-Hertz Tiered
Extragalactic Exploration (MIGHTEE) survey. At a newly measured redshift of , the system has strong emission in both the 1665MHz (
L) and 1667 MHz ( L) transitions,
with both narrow and broad components. We interpret the broad line as a
high-velocity-dispersion component of the 1667 MHz transition, with velocity km s with respect to the systemic velocity. The host galaxy has
a stellar mass of M and a
star-formation rate of SFR = 371 Myr, placing it dex
above the main sequence for star-forming galaxies at this redshift, and can be
classified as an ultra-luminous infrared galaxy. Alongside the optical imaging
data, which exhibits evidence for a tidal tail, this suggests that the OH
megamaser arises from a system that is currently undergoing a merger, which is
stimulating star formation and providing the necessary conditions for pumping
the OH molecule to saturation. The OHM is likely to be lensed, with a
magnification factor of , and perhaps more if the maser emitting
region is compact and suitably offset relative to the centroid of its host
galaxy's optical light. This discovery demonstrates that spectral line mapping
with the new generation of radio interferometers may provide important
information on the cosmic merger history of galaxies.Comment: 11 pages, accepted for publication in MNRA
MIGHTEE: multi-wavelength counterparts in the COSMOS field
In this paper we combine the Early Science radio continuum data from the
MeerKAT International GHz Tiered Extragalactic Exploration (MIGHTEE) Survey,
with optical and near-infrared data and release the cross-matched catalogues.
The radio data used in this work covers deg of the COSMOS field,
reaches a thermal noise of Jy/beam and contains radio
components. We visually inspect and cross-match the radio sample with optical
and near-infrared data from the Hyper Suprime-Cam (HSC) and UltraVISTA surveys.
This allows the properties of active galactic nuclei and star-forming
populations of galaxies to be probed out to . Additionally, we use
the likelihood ratio method to automatically cross-match the radio and optical
catalogues and compare this to the visually cross-matched catalogue. We find
that 94 per cent of our radio source catalogue can be matched with this method,
with a reliability of per cent. We proceed to show that visual
classification will still remain an essential process for the cross-matching of
complex and extended radio sources. In the near future, the MIGHTEE survey will
be expanded in area to cover a total of 20~deg; thus the combination
of automated and visual identification will be critical. We compare redshift
distribution of SFG and AGN to the SKADS and T-RECS simulations and find more
AGN than predicted at .Comment: 15 pages, 15 figures. Accepted for publication in MNRA
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