1,450 research outputs found
Anomalous gtt couplings in the Littlest Higgs Model with T-parity
In this work we calculate the leading electroweak (EW) corrections to the
anomalous coupling in the Littlest Higgs model with T-parity (LHT),
by applying the Goldstone boson equivalence theorem. In the LHT model, such
electroweak corrections arise from the loop diagrams of heavy fermions and the
``would-be'' Goldstone bosons. We further examine the EW corrections in the top
quark pair production via the quark annihilation process at the LHC. The
negative EW corrections in the Standard Model are partially canceled by the
positive EW corrections from the loops of the new heavy particles, and the
latter dominates in the large invariant mass of the top quark pair.Comment: version appeared in PR
GeV antiproton/gamma-ray excesses and the -boson mass anomaly: three faces of GeV dark matter particle?
For the newly discovered -boson mass anomaly, one of the simplest dark
matter (DM) models that can account for the anomaly without violating other
astrophysical/experimental constraints is the inert two Higgs doublet model, in
which the DM mass () is found to be within GeV. In this
model, the annihilation of DM via and would
produce antiprotons and gamma rays, and may account for the excesses identified
previously in both particles. Motivated by this, we re-analyze the AMS-02
antiproton and Fermi-LAT Galactic center gamma-ray data. For the antiproton
analysis, the novel treatment is the inclusion of the charge-sign-dependent
three-dimensional solar modulation model as constrained by the time-dependent
proton data. We find that the excess of antiprotons is more distinct than
previous results based on the force-field solar modulation model. The
interpretation of this excess as the annihilation of () requires a DM mass of () GeV and a
velocity-averaged cross section of . As for the
-ray data analysis, rather than adopting the widely-used spatial
template fitting, we employ an orthogonal approach with a data-driven spectral
template analysis. The fitting to the GeV -ray excess yields DM model
parameters overlapped with those to fit the antiproton excess via the
channel. The consistency of the DM particle properties required to account for
the -boson mass anomaly, the GeV antiproton excess, and the GeV -ray
excess suggest a common origin of them.Comment: 8 page
Retigeric Acid B Exhibits Antitumor Activity through Suppression of Nuclear Factor-ΞΊB Signaling in Prostate Cancer Cells in Vitro and in Vivo
Previously, we reported that retigeric acid B (RB), a natural pentacyclic triterpenic acid isolated from lichen, inhibited cell growth and induced apoptosis in androgen-independent prostate cancer (PCa) cells. However, the mechanism of action of RB remains unclear. In this study, we found that using PC3 and DU145 cells as models, RB inhibited phosphorylation levels of IΞΊBΞ± and p65 subunit of NF-ΞΊB in a time- and dosage-dependent manner. Detailed study revealed that RB blocked the nuclear translocation of p65 and its DNA binding activity, which correlated with suppression of NF-ΞΊB-regulated proteins including Bcl-2, Bcl-xL, cyclin D1 and survivin. NF-ΞΊB reporter assay suggested that RB was able to inhibit both constitutive activated-NF-ΞΊB and LPS (lipopolysaccharide)-induced activation of NF-ΞΊB. Overexpression of RelA/p65 rescued RB-induced cell death, while knockdown of RelA/p65 significantly promoted RB-mediated inhibitory effect on cell proliferation, suggesting the crucial involvement of NF-ΞΊB pathway in this event. We further analyzed antitumor activity of RB in in vivo study. In C57BL/6 mice carrying RM-1 homografts, RB inhibited tumor growth and triggered apoptosis mainly through suppressing NF-ΞΊB activity in tumor tissues. Additionally, DNA microarray data revealed global changes in the gene expression associated with cell proliferation, apoptosis, invasion and metastasis in response to RB treatment. Therefore, our findings suggested that RB exerted its anti-tumor effect by targeting the NF-ΞΊB pathway in PCa cells, and this could be a general mechanism for the anti-tumor effect of RB in other types of cancers as well
Fabrication of Densely Packed AlN Nanowires by a Chemical Conversion of Al2O3Nanowires Based on Porous Anodic Alumina Film
Porous alumina film on aluminum with gel-like pore wall was prepared by a two-step anodization of aluminum, and the corresponding gel-like porous film was etched in diluted NaOH solution to produce alumina nanowires in the form of densely packed alignment. The resultant alumina nanowires were reacted with NH3and evaporated aluminum at an elevated temperature to be converted into densely packed aluminum nitride (AlN) nanowires. The AlN nanowires have a diameter of 15β20 nm larger than that of the alumina nanowires due to the supplement of the additional evaporated aluminum. The results suggest that it might be possible to prepare other aluminum compound nanowires through similar process
Constraints on Large Extra Dimensions with Bulk Neutrinos
We consider right-handed neutrinos propagating in (large) extra
dimensions, whose only coupling to Standard Model fields is the Yukawa coupling
to the left-handed neutrino and the Higgs boson. These theories are attractive
as they can explain the smallness of the neutrino mass, as has already been
shown. We show that if is bigger than two, there are strong
constraints on the radius of the extra dimensions, resulting from the
experimental limit on the probability of an active state to mix into the large
number of sterile Kaluza-Klein states of the bulk neutrino. We also calculate
the bounds on the radius resulting from requiring that perturbative unitarity
be valid in the theory, in an imagined Higgs-Higgs scattering channel.Comment: 24 pages, 4 figures, revtex4. v2: Minor typos corrected, references
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Epidemiologic Features and Environmental Risk Factors of Severe Fever with Thrombocytopenia Syndrome, Xinyang, China
Background:Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease discovered in rural areas of Central China in 2009, caused by a novel bunyavirus, SFT
The Hidden Nematic Fluctuations in the Triclinic (Ca0.85La0.15)10(Pt3As8)(Fe2As2)5 Superconductor Revealed by Ultrafast Optical Spectroscopy
We reported the quasiparticle relaxation dynamics of an optimally doped
triclinic iron-based superconductor
(CaLa)(PtAs)(FeAs) with bulk
= 30 K using polarized ultrafast optical pump-probe spectroscopy. Our results
reveal anisotropic transient reflectivity induced by nematic fluctuations
develops below 120 K and persists in the superconducting
states. Measurements under high pump fluence reveal three distinct, coherent
phonon modes at frequencies of 1.6, 3.5, and 4.7 THz, corresponding to
, , and modes, respectively. The high-frequency
mode corresponds to the -axis polarized vibrations of FeAs
planes with a nominal electron-phonon coupling constant
0.139 0.02. Our findings suggest that the superconductivity and
nematic state are compatible but competitive at low temperatures, and the
phonons play an important role in the formation of Cooper pairs in
(CaLa)(PtAs)(FeAs).Comment: 6 pages, 3 figures and Supplemental Material
Shugoshin1 May Play Important Roles in Separation of Homologous Chromosomes and Sister Chromatids during Mouse Oocyte Meiosis
Background: Homologous chromosomes separate in meiosis I and sister chromatids separate in meiosis II, generating haploid gametes. To address the question why sister chromatids do not separate in meiosis I, we explored the roles of Shogoshin1 (Sgo1) in chromosome separation during oocyte meiosis. Methodology/Principal Findings: Sgo1 function was evaluated by exogenous overexpression to enhance its roles and RNAi to suppress its roles during two meioses of mouse oocytes. Immunocytochemistry and chromosome spread were used to evaluate phenotypes. The exogenous Sgo1 overexpression kept homologous chromosomes and sister chromatids not to separate in meiosis I and meiosis II, respectively, while the Sgo1 RNAi promoted premature separation of sister chromatids. Conclusions: Our results reveal that prevention of premature separation of sister chromatids in meiosis I requires th
Phosphor coated NiO-based planar inverted organometallic halide perovskite solar cells with enhanced efficiency and stability
This work investigates non-rare-earth phosphor (Sr4Al14O25:Mn4+, 0.5%Mg) with intensively red luminescence as a luminescent down-shifting layer for perovskite solar cells. The power conversion efficiency of the fabricated device with a structure of NiO/CH3NH3PbI3/[6,6]-phenyl C61-butyric acid methyl ester/Au coated with phosphor layer shows a 10% increase as compared with that of the control devices. Importantly, the phosphor layer coating can realize UV-protection as well as waterproof capability, achieving a reduced moisture-degradation of CH3NH3PbI3 perovskite upon applying an UV irradiation. Therefore, perovskite devices using this luminescent coating show a combined enhancement in both UV down-shifting conversion and long term stability. This can be expanded as a promising encapsulation technique in the perovskite solar cell community
Genome-wide association study identifies novel susceptibility loci for cutaneous squamous cell carcinoma
Cutaneous squamous cell carcinoma represents the second most common cutaneous malignancy, affecting 7β11% of Caucasians in the United States. The genetic determinants of susceptibility to cutaneous squamous cell carcinoma remain largely unknown. Here we report the results of a two-stage genome-wide association study of cutaneous squamous cell carcinoma, totalling 7,404 cases and 292,076 controls. Eleven loci reached genome-wide significance (P<5 Γ 10β8) including seven previously confirmed pigmentation-related loci: MC1R, ASIP, TYR, SLC45A2, OCA2, IRF4 and BNC2. We identify an additional four susceptibility loci: 11q23.3 CADM1, a metastasis suppressor gene involved in modifying tumour interaction with cell-mediated immunity; 2p22.3; 7p21.1 AHR, the dioxin receptor involved in anti-apoptotic pathways and melanoma progression; and 9q34.3 SEC16A, a putative oncogene with roles in secretion and cellular proliferation. These susceptibility loci provide deeper insight into the pathogenesis of squamous cell carcinoma
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