1,658 research outputs found
Loss of histone macroH2A1 in hepatocellular carcinoma cells promotes paracrine-mediated chemoresistance and CD4+CD25+FoxP3+ regulatory T cells activation
Rationale: Loss of histone macroH2A1 induces appearance of cancer stem cells (CSCs)-like cells in hepatocellular carcinoma (HCC). How CSCs interact with the tumor microenvironment and the adaptive immune system is unclear. Methods: We screened aggressive human HCC for macroH2A1 and CD44 CSC marker expression. We also knocked down (KD) macroH2A1 in HCC cells, and performed integrated transcriptomic and secretomic analyses. Results: Human HCC showed low macroH2A1 and high CD44 expression compared to control tissues. MacroH2A1 KD CSC-like cells transferred paracrinally their chemoresistant properties to parental HCC cells. MacroH2A1 KD conditioned media transcriptionally reprogrammed parental HCC cells activated regulatory CD4+/CD25+/FoxP3+ T cells (Tregs). Conclusions: Loss of macroH2A1 in HCC cells drives cancer stem-cell propagation and evasion from immune surveillance
Asynchronous Training of Word Embeddings for Large Text Corpora
Word embeddings are a powerful approach for analyzing language and have been
widely popular in numerous tasks in information retrieval and text mining.
Training embeddings over huge corpora is computationally expensive because the
input is typically sequentially processed and parameters are synchronously
updated. Distributed architectures for asynchronous training that have been
proposed either focus on scaling vocabulary sizes and dimensionality or suffer
from expensive synchronization latencies.
In this paper, we propose a scalable approach to train word embeddings by
partitioning the input space instead in order to scale to massive text corpora
while not sacrificing the performance of the embeddings. Our training procedure
does not involve any parameter synchronization except a final sub-model merge
phase that typically executes in a few minutes. Our distributed training scales
seamlessly to large corpus sizes and we get comparable and sometimes even up to
45% performance improvement in a variety of NLP benchmarks using models trained
by our distributed procedure which requires of the time taken by the
baseline approach. Finally we also show that we are robust to missing words in
sub-models and are able to effectively reconstruct word representations.Comment: This paper contains 9 pages and has been accepted in the WSDM201
The W43-MM1 mini-starburst ridge, a test for star formation efficiency models
Context: Star formation efficiency (SFE) theories are currently based on
statistical distributions of turbulent cloud structures and a simple model of
star formation from cores. They remain poorly tested, especially at the highest
densities. Aims: We investigate the effects of gas density on the SFE through
measurements of the core formation efficiency (CFE). With a total mass of
M, the W43-MM1 ridge is one of the most convincing
candidate precursor of starburst clusters and thus one of the best place to
investigate star formation. Methods: We used high-angular resolution maps
obtained at 3 mm and 1 mm within W43-MM1 with the IRAM Plateau de Bure
Interferometer to reveal a cluster of 11 massive dense cores (MDCs), and, one
of the most massive protostellar cores known. An Herschel column density image
provided the mass distribution of the cloud gas. We then measured the
'instantaneous' CFE and estimated the SFE and the star formation rate (SFR)
within subregions of the W43-MM1 ridge. Results: The high SFE found in the
ridge (6% enclosed in 8 pc) confirms its ability to form a
starburst cluster. There is however a clear lack of dense cores in the northern
part of the ridge, which may be currently assembling. The CFE and the SFE are
observed to increase with volume gas density while the SFR steeply decreases
with the virial parameter, . Statistical models of the SFR may
well describe the outskirts of the W43-MM1 ridge but struggle to reproduce its
inner part, which corresponds to measurements at low . It may be
that ridges do not follow the log-normal density distribution, Larson
relations, and stationary conditions forced in the statistical SFR models.Comment: 13 pages, 7 figures. Accepted by A&
ATLASGAL-selected massive clumps in the inner Galaxy: I. CO depletion and isotopic ratios
In the low-mass regime, it is found that the gas-phase abundances of
C-bearing molecules in cold starless cores rapidly decrease with increasing
density, as the molecules form mantles on dust grains. We study CO depletion in
102 massive clumps selected from the ATLASGAL 870 micron survey, and
investigate its correlation with evolutionary stage and with the physical
parameters of the sources. Moreover, we study the gradients in [12C]/[13C] and
[18O]/[17O] isotopic ratios across the inner Galaxy, and the virial stability
of the clumps. We use low-J emission lines of CO isotopologues and the dust
continuum emission to infer the depletion factor fD. RATRAN one-dimensional
models were also used to determine fD and to investigate the presence of
depletion above a density threshold. The isotopic ratios and optical depth were
derived with a Bayesian approach. We find a significant number of clumps with a
large fD, up to ~20. Larger values are found for colder clumps, thus for
earlier evolutionary phases. For massive clumps in the earliest stages of
evolution we estimate the radius of the region where CO depletion is important
to be a few tenths of a pc. Clumps are found with total masses derived from
dust continuum emission up to ~20 times higher than the virial mass, especially
among the less evolved sources. These large values may in part be explained by
the presence of depletion: if the CO emission comes mainly from the low-density
outer layers, the molecules may be subthermally excited, leading to an
overestimate of the dust masses. CO depletion in high-mass clumps seems to
behave as in the low-mass regime, with less evolved clumps showing larger
values for the depletion than their more evolved counterparts, and increasing
for denser sources. The C and O isotopic ratios are consistent with previous
determinations, and show a large intrinsic scatter.Comment: 20 pages, 17 figures, 38 pages of online material (tables and
figures
Giant Spin Seebeck Effect through an Interface Organic Semiconductor
Interfacing an organic semiconductor C60 with a non-magnetic metallic thin
film (Cu or Pt) has created a novel heterostructure that is ferromagnetic at
ambient temperature, while its interface with a magnetic metal (Fe or Co) can
tune the anisotropic magnetic surface property of the material. Here, we
demonstrate that sandwiching C60 in between a magnetic insulator (Y3Fe5O12:
YIG) and a non-magnetic, strong spin-orbit metal (Pt) promotes highly efficient
spin current transport via the thermally driven spin Seebeck effect (SSE).
Experiments and first principles calculations consistently show that the
presence of C60 reduces significantly the conductivity mismatch between YIG and
Pt and the surface perpendicular magnetic anisotropy of YIG, giving rise to
enhanced spin mixing conductance across YIG/C60/Pt interfaces. As a result, a
600% increase in the SSE voltage (VLSSE) has been realized in YIG/C60/Pt
relative to YIG/Pt. Temperature-dependent SSE voltage measurements on
YIG/C60/Pt with varying C60 layer thicknesses also show an exponential increase
in VLSSE at low temperatures below 200 K, resembling the temperature evolution
of spin diffusion length of C60. Our study emphasizes the important roles of
the magnetic anisotropy and the spin diffusion length of the intermediate layer
in the SSE in YIG/C60/Pt structures, providing a new pathway for developing
novel spin-caloric materials
Environmental contamination with clostridioides (Clostridium) difficile in Vietnam
AIMS: To investigate the prevalence, molecular type, and antimicrobial susceptibility of Clostridioides difficile in the environment in Vietnam, where little is known about C. difficile. METHODS AND RESULTS: Samples of pig faeces, soils from pig farms, potatoes, and the hospital environment were cultured for C. difficile. Isolates were identified and typed by polymerase chain reaction (PCR) ribotyping. The overall prevalence of C. difficile contamination was 24.5% (68/278). Clostridioides difficile was detected mainly in soils from pig farms and hospital soils, with 70%-100% prevalence. Clostridioides difficile was isolated from 3.4% of pig faecal samples and 5% of potato surfaces. The four most prevalent ribotypes (RTs) were RTs 001, 009, 038, and QX574. All isolates were susceptible to metronidazole, fidaxomicin, vancomycin, and amoxicillin/clavulanate, while resistance to erythromycin, tetracycline, and moxifloxacin was common in toxigenic strains. Clostridioides difficile RTs 001A+B+CDT- and 038A-B-CDT- were predominantly multidrug resistant. CONCLUSIONS: Environmental sources of C. difficile are important to consider in the epidemiology of C. difficile infection in Vietnam, however, contaminated soils are likely to be the most important source of C. difficile. This poses additional challenges to controlling infections in healthcare settings
Transaminase abnormalities and adaptations of the liver lobule manifest at specific cut-offs of steatosis
There is little documented evidence suggesting that liver fat is responsible for liver injury in the absence of other disease processes. We investigated the relationships between liver fat, aminotransferases and hepatic architecture in liver biopsies with simple steatosis. We identified 136 biopsies with simple steatosis from the Royal Free Hospital Archives with both clinical data and sufficient material. Digital image analysis was employed to measure fat proportionate area (mFPA). Hepatocyte area (HA) and lobule radius (LR) were also measured. There were significant increases in ALT (p < 0.001) and AST (p = 0.013) with increased fat content and evidence to suggest both 5% and 20% mFPA as a cut-off for raised ALT. In liver with increased fat content there were significant increases in HA (p < 0.001). LR also increased as mFPA increased to 10% (p < 0.001), at which point the lobule ceased to expand further and was counterbalanced with a decrease in the number of hepatocytes per lobule (p = 0.029). Consequently there are mechanisms of adaption in the liver architecture to accommodate the accumulation of fat and these are accompanied by significant increases in transaminases. These results support the generally accepted cut-off of 5% fat for steatosis and indicate 20% as a threshold of more severe liver injury
Required flows for aquatic ecosystems in Ma River, Vietnam
Ecological flow requirements for the Ma River in dry season were assessed in three reaches of Ma – Buoi, Ma – Len and Ma – Chu. 5 indictor fish species was chosen based on biodiversity survey and roles of those species in aquatic ecosystem as well as local communities. Biological and hydrological data (dry season of 2016- 2017) and 35 year recorded hydrological data were collected and analyzed as input data for a physical habitat model River HYdraulic and HABitat SImulation Model – RHYHABSIM. Model results shown that the optimal flows of the reaches were very much higher compare with the minimum annual low flow - MALF. In this study, MALF7day were applied to calculate the recommended minimum flows of the three reaches. The recommended required minimum flows for Ma – Buoi, Ma – Len and Ma – Chu reaches were 51 m3/s, 49 m3/s and 61 m3/s, respectively. It must be stressed that this study only assessed whether or not there is enough habitat available for the river to sustain a healthy ecosystem
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