4,758 research outputs found

    Brane Universe and Multigravity: Modification of gravity at large and small distances

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    We consider a modification of gravity at large distances in a Brane Universe which was discussed recently. In these models the modification of gravity at large distances is ultimately connected to existence of negative tension brane(s) and exponentially small tunneling factor. We discuss a general model which interpolates between Bi-gravity model and GRS model. We also discuss the possible mechanism of stabilization for negative tension branes in AdS background. Finally we show that extra degrees of freedom of massive gravitons do not lead to disastrous contradiction with General Relativity if the stabilization condition ∫dy−G(5)(TΌΌ−2T55)=0\int dy \sqrt{-G^{(5)}} (T^\mu_\mu-2T^5_5)=0 is implemented.Comment: 12 pages, 4 eps figures, LaTe

    Antitumor studies. Part 4: Design, synthesis, antitumor activity, and molecular docking study of novel 2-substituted 2-deoxoflavin-5-oxides, 2-deoxoalloxazine-5-oxides, and their 5-deaza analogs

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    Various novel 10-alkyl-2-deoxo-2-methylthioflavin-5-oxides and their 2-alkylamino derivatives were prepared by facile nitrosative cyclization of 6-(N-alkylanilino)-2-methylthiopyrimidin-4(3H)-ones followed by nucleophilic replacement of the 2-methylthio moiety by different amines, and acidic hydrolysis of the 2-methylthio moiety afforded the corresponding flavin derivatives. 2-Deoxo-2-methylthio-5-deazaalloxazines and 2-deoxo-2-methylthioalloxazine-5-oxides were also prepared by Vilsmeier reaction and by nitrosation of 6-anilino-2-methylthiopyrimidin-4(3H)-ones, respectively. Then, they were subjected to nucleophilic replacement with appropriate amines to produce the corresponding 2-alkylamino derivatives. Regiospecific N-3-alkylation of 2-deoxo-2-methylthioalloxazine-5-oxides was carried out with various alkylating agents in the usual way, The antitumor activities against CCRF-HSB-2 and KB tumor cells have been investigated in vitro, and many compounds showed promising antitumor activities. Furthermore, AutoDock molecular docking into PTK (PDB: 1t46) has been done for lead optimization of the aforementioned compounds as potential PTK inhibitors

    Infinitely Large New Dimensions

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    We construct intersecting brane configurations in Anti-de-Sitter space localizing gravity to the intersection region, with any number nn of extra dimensions. This allows us to construct two kinds of theories with infinitely large new dimensions, TeV scale quantum gravity and sub-millimeter deviations from Newton's Law. The effective 4D Planck scale MPlM_{Pl} is determined in terms of the fundamental Planck scale M∗M_* and the AdSAdS radius of curvature LL via the familiar relation MPl2∌M∗2+nLnM_{Pl}^2 \sim M_{*}^{2+n} L^n; LL acts as an effective radius of compactification for gravity on the intersection. Taking M∗∌M_* \sim TeV and L∌L \sim sub-mm reproduces the phenomenology of theories with large extra dimensions. Alternately, taking M∗∌L−1∌MPlM_* \sim L^{-1} \sim M_{Pl}, and placing our 3-brane a distance ∌100MPl−1\sim 100 M_{Pl}^{-1} away from the intersection gives us a theory with an exponential determination of the Weak/Planck hierarchy.Comment: 4 pages, revtex, no figure

    An investigation of viscous losses in radial inflow turbine nozzles

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    A theoretical model is developed to predict losses in radial inflow turbine nozzles. The analysis is presented in two parts. The first one evaluates the losses which occur across the vaned region of the nozzle, while the second part deals with the losses which take place in the vaneless field. It is concluded that the losses in a radial nozzle would not be greatly affected by the addition of a large vaneless space

    Signals of Supersymmetric Lepton Flavor Violation at the LHC

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    In a generic supersymmetric extension of the Standard Model, there will be lepton flavor violation at a neutral gaugino vertex due to misalignment between the lepton Yukawa couplings and the slepton soft masses. Sleptons produced at the LHC through the cascade decays of squarks and gluinos can give a sizable number of events with 4 leptons. This channel could give a clean signature of supersymmetric lepton flavor violation under conditions which are identified.Comment: 21 page

    Ghosts, Strong Coupling and Accidental Symmetries in Massive Gravity

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    We show that the strong self-interaction of the scalar polarization of a massive graviton can be understood in terms of the propagation of an extra ghost-like degree of freedom, thus relating strong coupling to the sixth degree of freedom discussed by Boulware and Deser in their Hamiltonian analysis of massive gravity. This enables one to understand the Vainshtein recovery of solutions of massless gravity as being due to the effect of the exchange of this ghost which gets frozen at distances larger than the Vainshtein radius. Inside this region, we can trust the two-field Lagrangian perturbatively, while at larger distances one can use the higher derivative formulation. We also compare massive gravity with other models, namely deconstructed theories of gravity, as well as DGP model. In the latter case we argue that the Vainshtein recovery process is of different nature, not involving a ghost degree of freedom.Comment: 21 page
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