53 research outputs found
Testing interacting dark matter and dark energy model with cosmological data
We investigate the model of dark matter-dark energy (DM-DE) interaction with
coupling strength proportional to the multiplication of dark sector densities
with different power indices . We first investigate the modification of the cosmic expansion
history, and then further develop the formalism to take into account the
cosmological perturbations and dark matter temperature evolution. We then use
the latest observational cosmology data, including cosmic microwave background
(CMB) data, baryon acoustic oscillations (BAO) data, redshift-space distortion
(RSD) data and Type Ia supernovae (SNe) data to constrain the model parameters.
We find in the phantom region, a positive is preferred by the data
above statistic significance. If we choose the power indices to be
integers or half-integers for {\it plausible} physics of particle interaction,
the allowed values within confidence regions are
and . The inclusion of BAO and RSD data from large-scale
structure and SNe data improves the constraints significantly. Our model
predicts lower values of at comparing to CDM
model, which alleviates the tension of CDM with various RSD data from
optical galaxy surveys. Overall, the DM-DE interaction model is consistent with
the current observational data, especially providing a better fit to the RSD
data.Comment: 12 pages, 8 figures, PRD accepte
Expression of mTOR conduction pathway in human osteosarcoma MG-63 cells and their stem cells, and the inhibitory effect of different doses of rapamycin
Purpose: To investigate the expressions of rapamycin target protein (mTOR) conduction pathway in human osteosarcoma MG-63 cells and their stem cells, and to examine the inhibitory effect of different doses of rapamycin.Methods: mTOR mRNA in osteosarcoma stem-like cells and human osteosarcoma MG-63 cells were determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR). The cells were treated with different doses of rapamycin and divided into low dose group (0.5 mg), medium dose group (1.0 mg), high dose group (2.0 mg) and blank (control) group. Apoptosis and cell cycle of MG-63 cells were determined by flow cytometry, while proliferation of MG-63 cells up was assessed by CCK-8 kit.Results: mTOR in human osteosarcoma MG-63 cells was significantly lower than that in osteosarcoma stem-like cells. Compared with the control group, mRNA expression levels of mTOR in MG-63 cells and osteosarcoma stem-like cells were significantly decreased after treatment with different concentrations of rapamycin (p < 0.05). MG-63 cells treated with various doses of rapamycin exhibited a significant decrease in their proliferation, compared with control group, while only the high rapamycin concentration group exhibited a significant decrease in osteosarcoma stem-like cell proliferation (p < 0.05). Treatment with rapamycin in MG-63 cells and osteosarcoma stem-like cells resulted in a significant increase in apoptosis, prolonged G0/G1 phase and shortened S phase (p < 0.05).Conclusion: Rapamycin inhibits the expression of mTOR mRNA in osteosarcoma stem-like and MG-63 cells. It also inhibits the proliferation and cell cycle formation of osteosarcoma stem-like cells and MG-63 cells via mTOR signal pathway. These findings may provide a new target for the treatment of osteosarcoma
UV/Ozone treatment to reduce metal-graphene contact resistance
We report reduced contact resistance of single-layer graphene devices by
using ultraviolet ozone (UVO) treatment to modify the metal/graphene contact
interface. The devices were fabricated from mechanically transferred, chemical
vapor deposition (CVD) grown, single layer graphene. UVO treatment of graphene
in the contact regions as defined by photolithography and prior to metal
deposition was found to reduce interface contamination originating from
incomplete removal of poly(methyl methacrylate) (PMMA) and photoresist. Our
control experiment shows that exposure times up to 10 minutes did not introduce
significant disorder in the graphene as characterized by Raman spectroscopy. By
using the described approach, contact resistance of less than 200 {\Omega}
{\mu}m was achieved, while not significantly altering the electrical properties
of the graphene channel region of devices.Comment: 17 pages, 5 figure
Probing the Intrinsic Shape and Alignment of Dark Matter Haloes using SDSS Galaxy Groups
We study the three-dimensional and projected shapes of galaxy groups in the
Sloan Digital Sky Survey Data Release 4, and examine the alignment between the
orientation of the central galaxy and the spatial distribution of satellite
galaxies. The projected ellipticity of a group is measured using the moments of
the discrete distribution of its member galaxies. We infer the
three-dimensional and projected axis ratios of their dark matter haloes by
comparing the measured ellipticity distributions with those obtained from Monte
Carlo simulations of projected, triaxial dark matter haloes with different axis
ratios. We find that the halo shape has a strong dependence on the halo mass.
While the haloes of low-mass groups are nearly spherical, those of massive
groups tend to be prolate. For groups containing at least four members, the
statistical distribution of their measured ellipticities does not have a strong
dependence on the colors of their central galaxies. Our analysis further shows
that the average three-dimensional axis ratio for haloes with is about , resulting in a
projected axis ratio of . Our results for the alignment between the
orientation of the central galaxy of a group and the distribution of their
satellite galaxies are in broad agreement with those obtained by Yang et al.
The distribution of satellite galaxies preferentially aligns with the major
axis of the central galaxy, with a clear dependence on both halo mass and
galaxy colors. (abridged)Comment: 13 pages, 10 figures and 2 tables. Accepted for publication in MNRA
Probing lepton flavor violation signal via e+ e- (gamma gamma) ---> l(i) anti-l(j) in the littlest Higgs model with T-parity at the ILC
In the littlest Higgs model with T-parity, the new interactions between the
mirror leptons and the Standard Model leptons can induce some lepton flavor
violation (LFV) processes at loop level. We study the possibility of the ILC to
probe the LFV production processes . Our results show that the rates of can reach 1 fb in optimal cases after reasonable kinematical
cuts, which implies that these processes may be observed at the ILC
The Study of the contribution of the LHT model to coupling
In the framework of the Littlest Higgs Model with T-parity (LHT), we study
the contributions of the new particles to couplings at one-loop
level. Based on these results, we further study the branching ratio and
the unpolarized forward-backward asymmetry . We find that the
correction of the new particles to couplings is mainly on the
left-handed coupling and has small part of the parameter space to alleviate the
deviation between theoretical predictions and experimental values. The
precision measurement value of can give severe constraints on the
relevant parameters. The constraints from the precision measurement value of
are very weak.Comment: 20 pages, 23 figure
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