219 research outputs found
Level Crossing Analysis of Burgers Equation in 1+1 Dimensions
We investigate the average frequency of positive slope ,
crossing the velocity field 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, , 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
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
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
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?
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, , at 68%
level of confidence, the combination of Gold sample SNIa, CMB shift parameter
and SDSS databases provides ,
, , hence a
spatially open universe with . The same
combination with SNLS supernova observation gives
, ,
consequently provides a spatially open universe
. 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
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, , where is a
constant of order and 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 and mimics a cosmological constant in the
late time, while it is possible to have provided the interaction is
taken into account. When , 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
confidence interval are: ,
and . Consequently
the total energy density of universe at present time in this model at 68% level
equates to .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
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 (the present matter content) and
(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
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
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
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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