219 research outputs found

    Level Crossing Analysis of Burgers Equation in 1+1 Dimensions

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    We investigate the average frequency of positive slope να+\nu_{\alpha}^{+}, crossing the velocity field u(x)uˉ=αu(x)- \bar u = \alpha in the Burgers equation. The level crossing analysis in the inviscid limit and total number of positive crossing of velocity field before creation of singularities are given. The main goal of this paper is to show that this quantity, να+\nu_{\alpha}^{+}, is a good measure for the fluctuations of velocity fields in the Burgers turbulence.Comment: 5 pages, 3 figure

    Anisotropic Inflation from Charged Scalar Fields

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    We consider models of inflation with U(1) gauge fields and charged scalar fields including symmetry breaking potential, chaotic inflation and hybrid inflation. We show that there exist attractor solutions where the anisotropies produced during inflation becomes comparable to the slow-roll parameters. In the models where the inflaton field is a charged scalar field the gauge field becomes highly oscillatory at the end of inflation ending inflation quickly. Furthermore, in charged hybrid inflation the onset of waterfall phase transition at the end of inflation is affected significantly by the evolution of the background gauge field. Rapid oscillations of the gauge field and its coupling to inflaton can have interesting effects on preheating and non-Gaussianities.Comment: minor changes, references added, figures are modified, conforms JCAP published versio

    Quantitative features of multifractal subtleties in time series

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    Based on the Multifractal Detrended Fluctuation Analysis (MFDFA) and on the Wavelet Transform Modulus Maxima (WTMM) methods we investigate the origin of multifractality in the time series. Series fluctuating according to a qGaussian distribution, both uncorrelated and correlated in time, are used. For the uncorrelated series at the border (q=5/3) between the Gaussian and the Levy basins of attraction asymptotically we find a phase-like transition between monofractal and bifractal characteristics. This indicates that these may solely be the specific nonlinear temporal correlations that organize the series into a genuine multifractal hierarchy. For analyzing various features of multifractality due to such correlations, we use the model series generated from the binomial cascade as well as empirical series. Then, within the temporal ranges of well developed power-law correlations we find a fast convergence in all multifractal measures. Besides of its practical significance this fact may reflect another manifestation of a conjectured q-generalized Central Limit Theorem

    TLR9-based immunotherapy for the treatment of allergic diseases

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    Toll-like receptors (TLRs), a family of pattern recognition receptors expressed on many cell types of innate immunity, recognize the pathogen-associated molecular patterns of microbes. The hygiene hypothesis suggests that a reduced microbial exposure in early childhood increases the susceptibility to allergic diseases due to deviation in development of the immune system. TLRs are key roles in the right and healthy direction of adaptive immunity with the induction of T-helper 2 toward Th1 immune responses and regulatory T cells. TLR ligand CpG-ODN-based immunomodulation is independent of allergen and it mainly affects innate immune system. While, CpG-oligodeoxynucleotide-based vaccination is allergen specific and induces adaptive immune system. The use of agonists of TLR9 in two distinct strategies of immunotherapy, immunomodulation and vaccination, could be presented as the curative method for the treatment of allergic diseases. First draft submitted: 29 August 2016; Accepted for publication: 8 February 2017; Published online: 17 March 2017 Keywords:  allergic diseases • immunotherapy • TLR9 • Toll-like receptor

    Is Thick Brane Model Consistent with the Recent Observations?

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    There exist many observational evidences implying the expansion of our universe is undergoing a late-time acceleration, the mechanism of this acceleration is yet unknown. In the so-called thick brane model this phenomena is attributed to the thickness of the brane along the extra dimension. In this study we mainly rely to the consistency of this model with most recent observational data related to the background evolution. The new Supernova Type Ia (SNIa) Gold sample and Supernova Legacy Survey (SNLS) data, the position of the acoustic peak at the last scattering surface from the WMAP observations and the baryon acoustic oscillation peak found in the Sloan Digital Sky Survey (SDSS) are used to constrain the free parameter of the thick codimension 1 brane model. To infer its consistency with age of our universe, we compare the age of old cosmological objects with what computed using the best fit values for the model parameters. When the universe is matter dominated, w=0w=0, at 68% level of confidence, the combination of Gold sample SNIa, CMB shift parameter and SDSS databases provides Ωm=0.310.02+0.02\Omega_m=0.31_{-0.02}^{+0.02}, ΩC=0.050.01+0.01\Omega_{\cal{C}}=0.05_{-0.01}^{+0.01}, wr=1.400.20+0.20w_r=-1.40_{-0.20}^{+0.20}, hence a spatially open universe with Ωk=0.210.08+0.08\Omega_k=0.21_{-0.08}^{+0.08}. The same combination with SNLS supernova observation gives Ωm=0.280.02+0.03\Omega_m=0.28_{-0.02}^{+0.03}, ΩC=0.0370.004+0.003\Omega_{\cal{C}}=0.037_{-0.004}^{+0.003}, wr=2.050.15+0.15w_r=-2.05_{-0.15}^{+0.15} consequently provides a spatially open universe Ωk=0.110.07+0.10\Omega_k=0.11_{-0.07}^{+0.10}. These results obviously seem to be in contradiction with the most recent WMAP results indicating a flat universe.Comment: 15 pages and 15 figures, V2: Added references and minor corrections, main results and conclusions unchange

    Interacting Ghost Dark Energy in Non-Flat Universe

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    A new dark energy model called "ghost dark energy" was recently suggested to explain the observed accelerating expansion of the universe. This model originates from the Veneziano ghost of QCD. The dark energy density is proportional to Hubble parameter, ρD=αH\rho_D=\alpha H, where α\alpha is a constant of order ΛQCD3\Lambda_{\rm QCD}^3 and ΛQCD100MeV\Lambda_{\rm QCD}\sim 100 MeV is QCD mass scale. In this paper, we extend the ghost dark energy model to the universe with spatial curvature in the presence of interaction between dark matter and dark energy. We study cosmological implications of this model in detail. In the absence of interaction the equation of state parameter of ghost dark energy is always wD>1w_D > -1 and mimics a cosmological constant in the late time, while it is possible to have wD<1w_D < -1 provided the interaction is taken into account. When k=0k = 0, all previous results of ghost dark energy in flat universe are recovered. To check the observational consistency, we use Supernova type Ia (SNIa) Gold sample, shift parameter of Cosmic Microwave Background radiation (CMB) and the Baryonic Acoustic Oscillation peak from Sloan Digital Sky Survey (SDSS). The best fit values of free parameter at 1σ1\sigma confidence interval are: Ωm0=0.350.03+0.02\Omega_m^0= 0.35^{+0.02}_{-0.03}, ΩD0=0.750.04+0.01\Omega_D^0=0.75_{-0.04}^{+0.01} and b2=0.080.03+0.03b^2=0.08^{+0.03}_{-0.03}. Consequently the total energy density of universe at present time in this model at 68% level equates to Ωtot0=1.100.05+0.02\Omega_{\rm tot}^0=1.10^{+0.02}_{-0.05}.Comment: 19 pages, 9 figures. V2: Added comments, observational consequences, references, figures and major corrections. Accepted for publication in General Relativity and Gravitatio

    Observational Constraints on a Variable Dark Energy Model

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    We study the effect of a phenomenological parameterized quintessence model on low, intermediate and high redshift observations. At low and intermediate redshifts, we use the Gold sample of supernova Type Ia (SNIa) data and recently observed size of baryonic acoustic peak from Sloan Digital Sky Survey (SDSS), to put constraint on the parameters of the quintessence model. At the high redshift, the same fitting procedure is done using WAMP data, comparing the location of acoustic peak with that obtain from the dark energy model. As a complementary analysis in a flat universe, we combine the results from the SNIa, CMB and SDSS. The best fit values for the model parameters are Ωm=0.270.02+0.02\Omega_m = 0.27^{+0.02}_{-0.02} (the present matter content) and w0=1.450.60+0.35w_0=-1.45^{+0.35}_{-0.60} (dark energy equation of state). Finally we calculate the age of universe in this model and compare it with the age of old stars and high redshift objectsComment: 10 pages, 12 figures, accepted in PR

    Long-range correlation and multifractality in Bach's Inventions pitches

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    We show that it can be considered some of Bach pitches series as a stochastic process with scaling behavior. Using multifractal deterend fluctuation analysis (MF-DFA) method, frequency series of Bach pitches have been analyzed. In this view we find same second moment exponents (after double profiling) in ranges (1.7-1.8) in his works. Comparing MF-DFA results of original series to those for shuffled and surrogate series we can distinguish multifractality due to long-range correlations and a broad probability density function. Finally we determine the scaling exponents and singularity spectrum. We conclude fat tail has more effect in its multifractality nature than long-range correlations.Comment: 18 page, 6 figures, to appear in JSTA

    A solution of the coincidence problem based on the recent galactic core black hole mass density increase

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    A mechanism capable to provide a natural solution to two major cosmological problems, i.e. the cosmic acceleration and the coincidence problem, is proposed. A specific brane-bulk energy exchange mechanism produces a total dark pressure, arising when adding all normal to the brane negative pressures in the interior of galactic core black holes. This astrophysically produced negative dark pressure explains cosmic acceleration and why the dark energy today is of the same order to the matter density for a wide range of the involved parameters. An exciting result of the analysis is that the recent rise of the galactic core black hole mass density causes the recent passage from cosmic deceleration to acceleration. Finally, it is worth mentioning that this work corrects a wide spread fallacy among brane cosmologists, i.e. that escaping gravitons result to positive dark pressure.Comment: 14 pages, 3 figure

    NMR investigations of the interaction between the azo-dye sunset yellow and Fluorophenol

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    The interaction of small molecules with larger noncovalent assemblies is important across a wide range of disciplines. Here, we apply two complementary NMR spectroscopic methods to investigate the interaction of various fluorophenol isomers with sunset yellow. This latter molecule is known to form noncovalent aggregates in isotropic solution, and form liquid crystals at high concentrations. We utilize the unique fluorine-19 nucleus of the fluorophenol as a reporter of the interactions via changes in both the observed chemical shift and diffusion coefficients. The data are interpreted in terms of the indefinite self-association model and simple modifications for the incorporation of a second species into an assembly. A change in association mode is tentatively assigned whereby the fluorophenol binds end-on with the sunset yellow aggregates at low concentration and inserts into the stacks at higher concentrations
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