256 research outputs found
Level Crossing Analysis of the Stock Markets
We investigate the average frequency of positive slope ,
crossing for the returns of market prices.
The method is based on stochastic processes which no scaling feature is
explicitly required. Using this method we define new quantity to quantify stage
of development and activity of stocks exchange. We compare the Tehran and
western stock markets and show that some stocks such as Tehran (TEPIX) and New
Zealand (NZX) stocks exchange are emerge, and also TEPIX is a non-active market
and financially motivated to absorb capital.Comment: 6 pages and 4 figure
Overexpression of microRNA-16 declines cellular growth, proliferation and induces apoptosis in human breast cancer cells
MicroRNAs (miRNA) are a large family of small single-stranded RNA molecules found in all multicellular organisms. Early studies have been shown that miRNA are involved in cancer development and progression, and this role can be done by working as an oncogenes and tumor suppressor genes, so manipulation of this molecules can be a promising approach in cancer therapy, and experimental results represented that the modification in breast cancer phenotype is possible by miRNA expression alteration. miR-16, which is located in 13q14 chromosome, plays critical roles as a tumor suppressor by targeting several oncogenes which regulate cell cycle and apoptosis. Hence, in the present study, we investigated whether miR-16 could decline growth and survival of MCF-7 cell line as model of human breast cancer. MCF-7 cell line was infected with lentiviruses containing miR-16 precursor sequence. The effects of ectopic expression of miR-16 on breast cancer phenotype were examined by cell cycle analysis and apoptosis assays. miR-16 cytotoxicity effect was measured by the MTT assay. We showed that the miR-16 overexpression reduces Cyclin D1 and BCL2 at messenger RNA (mRNA) and protein levels in MCF-7 cell line. In addition, this is found that enforced expression of miR-16 decreases cell growth and proliferation and induces apoptosis in MCF-7 cells. In conclusion, our results revealed that upregulation of miR-16 would be a potential approach for breast cancer therapy. © 2015, The Society for In Vitro Biology
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
Uncertainty in the Fluctuations of the Price of Stocks
We report on a study of the Tehran Price Index (TEPIX) from 2001 to 2006 as
an emerging market that has been affected by several political crises during
the recent years, and analyze the non-Gaussian probability density function
(PDF) of the log returns of the stocks' prices. We show that while the average
of the index did not fall very much over the time period of the study, its
day-to-day fluctuations strongly increased due to the crises. Using an approach
based on multiplicative processes with a detrending procedure, we study the
scale-dependence of the non-Gaussian PDFs, and show that the temporal
dependence of their tails indicates a gradual and systematic increase in the
probability of the appearance of large increments in the returns on approaching
distinct critical time scales over which the TEPIX has exhibited maximum
uncertainty.Comment: 5 pages, 5 figures. Accepted to appear in IJMP
Long range correlation in cosmic microwave background radiation
We investigate the statistical anisotropy and Gaussianity of temperature
fluctuations of Cosmic Microwave Background radiation (CMB) data from {\it
Wilkinson Microwave Anisotropy Probe} survey, using the multifractal detrended
fluctuation analysis, rescaled range and scaled windowed variance methods. The
multifractal detrended fluctuation analysis shows that CMB fluctuations has a
long range correlation function with a multifractal behavior. By comparing the
shuffled and surrogate series of CMB data, we conclude that the multifractality
nature of temperature fluctuation of CMB is mainly due to the long-range
correlations and the map is consistent with a Gaussian distribution.Comment: 10 pages, 7 figures, V2: Added comments, references and major
correction
Relationships among serum receptor of nuclear factor-kappaB ligand, osteoprotegerin, high-sensitivity C-reactive protein, and bone mineral density in postmenopausal women: osteoimmunity versus osteoinflammatory.
Abstract
OBJECTIVE:
The aim of this study was to investigate the correlations among circulating osteoprotegerin (OPG), the receptor activator of nuclear factor-kappaB ligand (RANKL), high-sensitivity C-reactive protein (hsCRP), and bone mineral density (BMD) in healthy postmenopausal women.
METHODS:
In a population-based study, highly specific enzyme-linked immunosorbent assay methods were used to evaluate the sera of 382 healthy Iranian postmenopausal women (mean age +/- SD, 58.7 +/- 7.5 y) for RANKL, OPG, hsCRP, degradation products of C-terminal telopeptides of type I collagen, and osteocalcin. BMD was determined for the lumbar spine (L2-L4) and the proximal femur using dual-energy x-ray absorptiometry.
RESULTS:
Circulating levels of OPG (r = 0.30, P < 0.001) and the RANKL/OPG ratio (r = -0.17, P < 0.001) were significantly associated with age. The geometric mean of hsCRP was 1.89 mg/L (SE, 1.05) in the population studied. There was a significant correlation between log(hsCRP) levels and body mass index (BMI; r = 0.36, P < 0.001). Multivariate linear analyses revealed that age (beta = -0.295, P < 0.001), BMI (beta = 0.464, P < 0.001), RANKL (beta = -0.105, P = 0.014), and OPG (beta = 0.098, P = 0.029) were the independent determinants for lumbar BMD (R(2) = 0.35). Age (beta = -0.250, P < 0.001), BMI (beta = 0.486, P < 0.001), and RANKL (beta = -0.110, P = 0.009) were independently correlated with femoral neck BMD (R(2) = 0.36). Age- and BMI-adjusted analysis by quartiles of log-transformed hsCRP did not reveal an association with BMD, serum levels of biochemical markers of bone turnover, RANKL, or OPG
Multifractal analysis of stress time series during ultrathin lubricant film melting
Melting of an ultrathin lubricant film confined between two atomically flat
surfaces is we studied using the rheological model for viscoelastic matter
approximation. Phase diagram with domains, corresponding to sliding, dry, and
two types of friction regimes has been built taking into account
additive noises of stress, strain, and temperature of the lubricant. The stress
time series have been obtained for all regimes of friction using the
Stratonovich interpretation. It has been shown that self-similar regime of
lubricant melting is observed when intensity of temperature noise is much
larger than intensities of strain and stress noises. This regime is defined by
homogenous distribution, at which characteristic stress scale is absent. We
study stress time series obtained for all friction regimes using multifractal
detrended fluctuation analysis. It has been shown that multifractality of these
series is caused by different correlations that are present in the system and
also by a power-law distribution. Since the power-law distribution is related
to small stresses, this case corresponds to self-similar solid-like lubricant.Comment: 22 pages, 10 figures, 41 reference
The metabolic syndrome is not associated with homocysteinemia: The Persian Gulf Healthy Heart Study
Background: It is uncertain whether homocysteine
and the metabolic syndrome or its components are related
in the general population, as studies investigating the
association between homocysteine levels and insulin resistance
have shown conflicting results. Methods: In an ancillary
study to the Persian Gulf Healthy Heart Study, a cohort
study of Iranian men and women aged ≥25 yr, a random sample
of 1754 subjects were evaluated for the association of
plasma homocysteine levels and the metabolic syndrome using
National Cholesterol Education Program (NCEP)-Adult
Treatment Panel (ATP)-III criteria. Total homocysteine levels
and high sensitivity C-reactive protein (CRP) were determined
by enzyme-linked immunosorbent assays. Results: Subjects
with lower HDL-cholesterol and higher blood pressure
showed significantly higher homocysteine levels (p=0.001
and p<0.0001; respectively). There was no significant difference
in serum levels of homocysteine between subjects with
and without the metabolic syndrome. In multiple logistic regression
analysis, the metabolic syndrome did not show a
significant association with serum homocysteine levels after
adjusting for sex, age, smoking, fruit and vegetable intake
pattern, body mass index, and physical inactivity. Concurrent
elevated CRP levels and the metabolic syndrome also did not
show a significant association with serum homocysteine levels
after adjusting for sex, age, and lifestyle cardiovascular
risk factors. Conclusions: There was no association between
the metabolic syndrome using NCEP-ATPIII criteria and homocysteinemia
in this study. These data refute the hypothesis
that homocysteine levels are influenced by the metabolic
syndrome, at least in general healthy population
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
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