557 research outputs found
Some remarks on compositeness of
Recently LHCb experimental group find an exotic state from the
process . A key question is if it is just a
molecule or may have confined tetraquark ingredient. To investigate this,
different methods are taken, including two channel ( and
) K-matrix unitarization and single channel Flatt\'e-like
parametrization method analysed by pole counting rule and spectral density
function sum rule. It demonstrates that is a molecular state, though
the possibility that there may exist elementary ingredient can not be excluded,
by rough analysis on its production rate
as a molecule from the pole counting rule
A comprehensive study on the nature of the resonant structure is
carried out in this work. By constructing the pertinent effective Lagrangians
and considering the important final-state-interaction effects, we first give a
unified description to all the relevant experimental data available, including
the and invariant mass distributions from the process, the distribution from and
also the spectrum in the process.
After fitting the unknown parameters to the previous data, we search the pole
in the complex energy plane and find only one pole in the nearby energy region
in different Riemann sheets. Therefore we conclude that is of
molecular nature, according to the pole counting rule
method~[Nucl.~Phys.~A543, 632 (1992); Phys.~Rev.~D 35,~1633 (1987)]. We
emphasize that the conclusion based upon the pole counting method is not
trivial, since both the contact interactions and the explicit
exchanges are introduced in our analyses and they lead to the same
conclusion.Comment: 21 pages, 9 figures. To match the published version in PRD.
Additional discussion on the spectral density function is include
Quasi-two-body decays in the perturbative QCD
In this work, we investigate the quasi-two-body decays with using the perturbative QCD(PQCD)
approach. The description of final state interactions between the pair
is achieved through the two-meson distribution amplitudes(DAs), which are
normalized to the time-like form factor. The PQCD predictions on the branching
ratios of the quasi-two-body decays show an obvious
hierarchy: and .
From the invariant mass -dependence of the decay spectrum for each
channel, one can find that the branching fraction is concentrated in a narrow
region around the pole mass. So one can obtain the branching ratios for
the corresponding two-body decays under the narrow width
approximation. We find that the branching ratios of the decays
are consistent well with the previous PQCD calculations within errors. These
predictions will be tested by the future experiments.Comment: 12 pages, 3 figures, accepted for publication in Chin. Phys.
Extraction Method of Electrical Fire Material Evidence
AbstractIt is important for material evidence of identification in fire investigation, and the extraction method of material evidence has the most direct effect for the result of identification. How to extract the most valuable material evidence and find out the cause of the fire to provide a powerful evidence for fire, it is a skill for fire investigators must master. The efficiency of fire investigation will be greatly enhanced with the accuracy of evidence extraction, ensure that the reason is accurate for investigation
A tetranuclear cobalt(III) cluster with 2-(hydroxymethyl)pyridine ligands
In the title compound, tetrakis[μ3-(2-pyridyl)methanolato]tetrakis[bromido(methanol)cobalt(III)] tetrabromide 2-(hydroxymethyl)pyridine tetrasolvate dihydrate, [Co4Br4(C6H6NO)4(CH3OH)4]Br4·4C6H7NO4·2H2O, the cation comprises a [Co4O4] cubane-type core ( symmetry). The four CoIII ions and bridging O atoms from four (2-pyridyl)methanolate anions are located at alternating vertices of the cube, with bromide ions and methanol ligands on the exterior of the core, completing a distorted octahedral geometry. The structure is stablized by intermolecular O—H⋯Br and O—H⋯O interactions
Gemcitabine enhances cell invasion via activating HAb18G/CD147-EGFR-pSTAT3 signaling
Pancreatic cancer, one of the most lethal cancers, has very poor 5-year survival partly due to gemcitabine resistance. Recently, it was reported that chemotherapeutic agents may act as stressors to induce adaptive responses and to promote chemoresistance in cancer cells. During long-term drug treatment, the minority of cancer cells survive and acquire an epithelial-mesenchymal transition phenotype with increased chemo-resistance and metastasis. However, the short-term response of most cancer cells remains unclear. This study aimed to investigate the short-term response of pancreatic cancer cells to gemcitabine stress and to explore the corresponding mechanism. Our results showed that gemcitabine treatment for 24 hours enhanced pancreatic cancer cell invasion. In gemcitabine-treated cells, HAb18G/CD147 was up-regulated; and HAb18G/CD147 down-regulation or inhibition attenuated gemcitabine-enhanced invasion. Mechanistically, HAb18G/CD147 promoted gemcitabine-enhanced invasion by activating the EGFR (epidermal growth factor receptor)-STAT3 (signal transducer and activator of transcription 3) signaling pathway. Inhibition of EGFR-STAT3 signaling counteracted gemcitabine-enhanced invasion, and which relied on HAb18G/CD147 levels. In pancreatic cancer tissues, EGFR was highly expressed and positively correlated with HAb18G/CD147. These data indicate that pancreatic cancer cells enhance cell invasion via activating HAb18G/CD147-EGFR-pSTAT3 signaling. Our findings suggest that inhibiting HAb18G/CD147 is a potential strategy for overcoming drug stress-associated resistance in pancreatic cancer
CCL2: An important cytokine in normal and pathological pregnancies: A review
C-C motif ligand 2 (CCL2), also known as monocytic chemotactic protein 1 (MCP-1), is an integral chemotactic factor which recruits macrophages for the immune response. Together with its receptors (e.g., CCR2, ACKR1, and ACKR2), they exert noticeable influences on various diseases of different systems. At the maternal-fetal interface, CCL2 is detected to be expressed in trophoblasts, decidual tissue, the myometrium, and others. Meanwhile, existing reports have determined a series of physiological regulators of CCL2, which functions in maintaining normal recruitment of immunocytes, tissue remodeling, and angiogenesis. However, abnormal levels of CCL2 have also been reported to be associated with adverse pregnancy outcomes such as spontaneous abortion, preeclampsia and preterm labor. In this review, we concentrate on CCL2 expression at the maternal-fetal interface, as well as its precise regulatory mechanisms and classic signaling pathways, to reveal the multidimensional aspects of CCL2 in pregnancy
Astrometric Reduction of Saturnian Satellites with Cassini-ISS Images Degraded by Trailed Stars
Imaging Science Subsystem (ISS) mounted on the Cassini spacecraft has taken a
lot of images, which provides an important source of high-precision astrometry
of some planets and satellites. However, some of these images are degraded by
trailed stars. Previously, these degraded images cannot be used for astrometry.
In this paper, a new method is proposed to detect and compute the centers of
these trailed stars automatically. The method is then performed on the
astrometry of ISS images with trailed stars. Finally, we provided 658
astrometric positions between 2004 and 2017 of several satellites that include
Enceladus, Dione, Tethys, Mimas and Rhea. Compared with the JPL ephemeris
SAT427, the mean residuals of these measurements are 0.11 km and 0.26 km in
right ascension and declination, respectively. Their standard deviations are
1.08 km and 1.37 km, respectively. The results show that the proposed method
performs astrometric measurements of Cassini ISS images with trailed stars
effectively
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