1,278 research outputs found
Multipole Expansion for the Electron-Nucleus Scattering at High Energies in the Unified Electroweak Theory
The article presents the multipole expansion for the electron-nucleus
scattering cross section at high energies within the framework of the unified
electroweak theory. The electroweak currents of the nucleus are expanded into
simple components with definite angular momentum, which are called the
multipole form factors. The multipole expansion of the cross section is a
consequence of the above expansion. Besides the familiar electromagnetic form
factors, there are weak form factors related to weak interactions,
corresponding to the vector and axial (pseudovector) weak currents. We do not
use the impulse approximation, the multipole form factors are calculated
directly, using only the Born approximation. We will present some examples in
the next paper.Comment: 7 pages, 0 figur
Microbial ecology of Thiobacillus ferrooxidans
FINAL TECHNICAL REPORT
TO
U.S. DEPARTMENT OF THE INTERIOR
Geological Survey
Washington. D.C.The contents of this report were developed in part under a grant from
the Department of the Interior, U.S. Geological Survey. Grant number 14-08-0001-61313
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
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&
Large scale IRAM 30m CO-observations in the giant molecular cloud complex W43
We aim to give a full description of the distribution and location of dense
molecular clouds in the giant molecular cloud complex W43. It has previously
been identified as one of the most massive star-forming regions in our Galaxy.
To trace the moderately dense molecular clouds in the W43 region, we initiated
an IRAM 30m large program, named W43-HERO, covering a large dynamic range of
scales (from 0.3 to 140 pc). We obtained on-the-fly-maps in 13CO (2-1) and C18O
(2-1) with a high spectral resolution of 0.1 km/s and a spatial resolution of
12". These maps cover an area of ~1.5 square degrees and include the two main
clouds of W43, as well as the lower density gas surrounding them. A comparison
with Galactic models and previous distance calculations confirms the location
of W43 near the tangential point of the Scutum arm at a distance from the Sun
of approximately 6 kpc. The resulting intensity cubes of the observed region
are separated into sub-cubes, centered on single clouds which are then analyzed
in detail. The optical depth, excitation temperature, and H2 column density
maps are derived out of the 13CO and C18O data. These results are then compared
with those derived from Herschel dust maps. The mass of a typical cloud is
several 10^4 solar masses while the total mass in the dense molecular gas (>100
cm^-3) in W43 is found to be about 1.9e6 solar masses. Probability distribution
functions obtained from column density maps derived from molecular line data
and Herschel imaging show a log-normal distribution for low column densities
and a power-law tail for high densities. A flatter slope for the molecular line
data PDF may imply that those selectively show the gravitationally collapsing
gas
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
Strained Silicon Complementary TFET SRAM: Experimental Demonstration and Simulations
A half SRAM cell with strained Si nanowire complementary tunnel-FETs (TFETs) was fabricated and characterized to explore the feasibility and functionality of 6T-SRAM based on TFETs. Outward-faced n-TFETs are used as access-transistors. Static measurements were performed to determine the SRAM butterfly curves, allowing the assessment of cell functionality and stability. The forward p-i-n leakage of the access-transistor at certain bias configurations leads to malfunctioning storage operation, even without the contribution of the ambipolar behavior. At large VDD, lowering of the bit-line bias is needed to mitigate such effect, demonstrating functional hold, read and write operations. Circuit simulations were carried out using a Verilog-A compact model calibrated on the experimental TFETs, providing a better understanding of the TFET SRAM operation at different supply voltages and for different cell sizing and giving an estimate of the dynamic performance of the cell
Complete Fusion Enhancement and Suppression of Weakly Bound Nuclei at Near Barrier Energies
We consider the influence of breakup channels on the complete fusion of
weakly bound systems in terms of dynamic polarization potentials. It is argued
that the enhancement of the cross section at sub-barrier energies may be
consistent with recent experimental observations that nucleon transfer, often
leading to breakup, is dominant compared to direct breakup. The main trends of
the experimental complete fusion cross section for Li + Bi are
analyzed in the framework of the DPP approach.Comment: 12 pages, 2 figure
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