236 research outputs found
S_4 x Z_2 Flavor Symmetry in Supersymmetric Extra U(1) Model
We propose a E_6 inspired supersymmetric model with a non-Abelian discrete
flavor symmetry (S_4 group); that is, SU(3)_c x SU(2)_W x U(1)_Y x U(1)_X x S_4
x Z_2. In our scenario, the additional abelian gauge symmetry; U(1)_X, not only
solves the mu-problem in the minimal Supersymmetric Standard Model(MSSM), but
also requires new exotic fields which play an important role in solving flavor
puzzles. If our exotic quarks can be embedded into a S_4 triplet, which
corresponds to the number of the generation, one finds that dangerous proton
decay can be well-suppressed. Hence, it might be expected that the generation
structure for lepton and quark in the SM(Standard Model) can be understood as a
new system in order to stabilize the proton in a supersymemtric standard model
(SUSY). Moreover, due to the nature of the discrete non-Abelian symmetry
itself, Yukawa coupling constants of our model are drastically reduced. In our
paper, we show two predictive examples of the models for quark sector and
lepton sector, respectively.Comment: 14 pages, 4 tables. Flavon sector and references are added. Sentences
are modifie
DEM Simulation of Soil Loosening Process Caused by a Vibrating Subsoiler
Rosana G. Moreira, Editor-in-Chief; Texas A&M UniversityThis is a paper from International Commission of Agricultural Engineering (CIGR, Commission Internationale du Genie Rural) E-Journal Volume 9 (2007): DEM Simulation of Soil Loosening Process Caused by a Vibrating Subsoiler. Manuscript PM 05 010. Vol. IX. November, 2007
“Paradoxical shrinkage” of coronary arterial wall may contribute to luminal narrowing in stable angina but not in acute myocardial infarction
<Abstract of published report>The Effect of ONO-3708,a Novel TXA_2 Receptor Antagonist, on U-46619-Induced Contraction of Guinea Pig and Human Tracheal Strips in vitro and on Bronchoconstriction in Guinea Pigs in vivo.
TGF-β-driven reduction of cytoglobin leads to oxidative DNA damage in stellate cells during non-alcoholic steatohepatitis
BACKGROUND: Cytoglobin (CYGB) is a respiratory protein that acts as a scavenger of reactive oxygen species. Although CYGB is expressed uniquely in hepatic stellate cells (HSCs) in the liver, the molecular role of CYGB in human HSC activation and human liver disease remains uncharacterised. The aim of this study was to reveal the mechanism by which TGF-β1/SMAD2 pathway regulates human CYGB promoter and the pathophysiological function of CYGB in human non-alcoholic steatohepatitis (NASH). METHODS: Immunohistochemical staining was performed using human NASH biopsy specimens. Molecular and biochemical analysis were performed by western blotting, quantitative PCR, and luciferase and immunoprecipitation assays. Hydroxyl radicals (•OH) and oxidative DNA damage were measured using an •OH-detectable probe and 8-hydroxy-2’-deoxyguanosine (8-OHdG) ELISA. RESULTS: In culture, TGF-β1-pretreated human hepatic stellate cells (HHSteCs) exhibited lowered CYGB levels together with increased NADPH oxidase 4 (NOX4) expression and were primed for H_{2}O_{2}-triggered OH production and 8-OHdG generation. Overexpression of human CYGB in HHSteCs cancelled out those effects of TGF-β1. Electron spin resonance demonstrated direct •OH-scavenging activity of recombinant human CYGB. Mechanistically, pSMAD2 reduced CYGB transcription by recruiting the M1 repressor isoform of SP3 to the human CYGB promoter at nucleotide positions +2–{+}^13 from the transcription start site. The same repression did not occur on the mouse Cygb promoter. TGF-β1/SMAD3 mediated αSMA and collagen expression. Consistent with those observations in cultured HHSteCs, CYGB expression was negligible, but 8-OHdG was abundant, in activated αSMA^{+}pSMAD2^{+}- and αSMA^{+}NOX4^{+}-positive hepatic stellate cells from human NASH patients with advanced fibrosis. CONCLUSIONS: Downregulation of CYGB by the TGF-β1/pSMAD2/SP3-M1 pathway brings about •OH-dependent oxidative DNA damage in activated hepatic stellate cells from human patients with NASH
Discrete symmetries and models of flavor mixing
Evidences of a discrete symmetry behind the pattern of lepton mixing are
analyzed. The program of "symmetry building" is outlined. Generic features and
problems of realization of this program in consistent gauge models are
formulated. The key issues include the flavor symmetry breaking, connection of
mixing and masses, {\it ad hoc} prescription of flavor charges, "missing"
representations, existence of new particles, possible accidental character of
the TBM mixing. Various ways are considered to extend the leptonic symmetries
to the quark sector and to reconcile them with Grand Unification. In this
connection the quark-lepton complementarity could be a viable alternative to
TBM. Observational consequences of the symmetries and future experimental tests
of their existence are discussed.Comment: 14 pages, 5 figures. Talk given at the Symposium "DISCRETE 2010", 6 -
11 December 2010, La Sapienza, Rome, Ital
COMPARISON OF SOLUTION ALGORITHM FOR FLOW AROUND A SQUARE CYLINDER
ABSTRACT Numerical accuracy, numerical stability and calculation time are all important factors in the computational fluid dynamics. In this study, we compare two solution algorithms, the Simplified Marker and Cell (SMAC) method in the MAC-type methods and the Semi-Implicit Method for Pressure-Linked Equation (SIMPLE) algorithm in the SIMPLE-type algorithms, with respect to flow around a square cylinder in constant density and unsteady-state calculations using a staggered grid to investigate the numerical accuracy, the numerical stability and the computational time. For the flow around a square cylinder, the SMAC and SIMPLE solutions are in excellent agreement at the Strouhal number, drag and lift coefficients. However, SMAC is more unstable than SIMLE with a large Courant number. The computational time of the SMAC is shorter than that of the SIMPLE with a small Courant number
Mass bound of the lightest neutral Higgs scalar in the extra U(1) models
The upper mass bound of the lightest neutral Higgs scalar is studied in the
problem solvable extra U(1) models by using the analysis of the
renormalization group equations. In order to restrict the parameter space we
take account of a condition of the radiative symmetry breaking and some
phenomenological constraints. We compare the bound obtained based on this
restricted parameter space with the one of the next to the minimal
supersymmetric standard model (NMSSM). Features of the scalar potential and
renormalization group equations of the Yukawa couplings among Higgs chiral
supermultiplets are rather different between them. They can reflect in this
bound.Comment: 22 pages, latex, 11 eps-figure
Cancer cells produce liver metastasis via gap formation in sinusoidal endothelial cells through proinflammatory paracrine mechanisms
Intracellular gap (iGap) formation in liver sinusoidal endothelial cells (LSECs) is caused by the destruction of fenestrae and appears under pathological conditions; nevertheless, their role in metastasis of cancer cells to the liver remained unexplored. We elucidated that hepatotoxin-damaged and fibrotic livers gave rise to LSECs-iGap formation, which was positively correlated with increased numbers of metastatic liver foci after intrasplenic injection of Hepa1-6 cells. Hepa1-6 cells induced interleukin-23-dependent tumor necrosis factor-α (TNF-α) secretion by LSECs and triggered LSECs-iGap formation, toward which their processes protruded to transmigrate into the liver parenchyma. TNF-α triggered depolymerization of F-actin and induced matrix metalloproteinase 9 (MMP9), intracellular adhesion molecule 1, and CXCL expression in LSECs. Blocking MMP9 activity by doxycycline or an MMP2/9 inhibitor eliminated LSECs-iGap formation and attenuated liver metastasis of Hepa1-6 cells. Overall, this study revealed that cancer cells induced LSEC-iGap formation via proinflammatory paracrine mechanisms and proposed MMP9 as a favorable target for blocking cancer cell metastasis to the liver
Towards Minimal S4 Lepton Flavor Model
We study lepton flavor models with the flavor symmetry. We construct
simple models with smaller numbers of flavon fields and free parameters, such
that we have predictions among lepton masses and mixing angles. The model with
a triplet flavon is not realistic, but we can construct realistic models
with two triplet flavons, or one triplet and one doublet flavons.Comment: 18 pages, 4 figures, references are adde
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