38 research outputs found
Characteristic distributions of finite-time Lyapunov exponents
We study the probability densities of finite-time or \local Lyapunov
exponents (LLEs) in low-dimensional chaotic systems. While the multifractal
formalism describes how these densities behave in the asymptotic or long-time
limit, there are significant finite-size corrections which are coordinate
dependent. Depending on the nature of the dynamical state, the distribution of
local Lyapunov exponents has a characteristic shape. For intermittent dynamics,
and at crises, dynamical correlations lead to distributions with stretched
exponential tails, while for fully-developed chaos the probability density has
a cusp. Exact results are presented for the logistic map, . At
intermittency the density is markedly asymmetric, while for `typical' chaos, it
is known that the central limit theorem obtains and a Gaussian density results.
Local analysis provides information on the variation of predictability on
dynamical attractors. These densities, which are used to characterize the {\sl
nonuniform} spatial organization on chaotic attractors are robust to noise and
can therefore be measured from experimental data.Comment: To be appear in Phys. Rev
Microwave assisted synthesis of novel bis-flavone dimers as new anticancer agents
In this study we describe a microwave based click chemistry method used to prepare a family of novel bis-flavone dimers. The substituted 7-hydroxy and 4â-hydroxy flavonoids were linked through a triazole ring. The compounds were easily synthesized and purified in high yields. The bis-flavonoids were tested on different cell lines including HCT116, HepG2, MCF7 and MOLT-4. Several analogues showed to have anticancer activity with IC50 values in the range of 20-60 ”M. Flavonoids are known for their anticancer properties and this method provides the basis for new medicinal structures
Active Brownian Particles. From Individual to Collective Stochastic Dynamics
We review theoretical models of individual motility as well as collective
dynamics and pattern formation of active particles. We focus on simple models
of active dynamics with a particular emphasis on nonlinear and stochastic
dynamics of such self-propelled entities in the framework of statistical
mechanics. Examples of such active units in complex physico-chemical and
biological systems are chemically powered nano-rods, localized patterns in
reaction-diffusion system, motile cells or macroscopic animals. Based on the
description of individual motion of point-like active particles by stochastic
differential equations, we discuss different velocity-dependent friction
functions, the impact of various types of fluctuations and calculate
characteristic observables such as stationary velocity distributions or
diffusion coefficients. Finally, we consider not only the free and confined
individual active dynamics but also different types of interaction between
active particles. The resulting collective dynamical behavior of large
assemblies and aggregates of active units is discussed and an overview over
some recent results on spatiotemporal pattern formation in such systems is
given.Comment: 161 pages, Review, Eur Phys J Special-Topics, accepte
TERT promoter mutations are highly recurrent in SHH subgroup medulloblastoma
Telomerase reverse transcriptase (TERT) promoter mutations were recently shown to drive telomerase activity in various cancer types, including medulloblastoma. However, the clinical and biological implications of TERT mutations in medulloblastoma have not been described. Hence, we sought to describe these mutations and their impact in a subgroup-specific manner. We analyzed the TERT promoter by direct sequencing and genotyping in 466 medulloblastomas. The mutational distributions were determined according to subgroup affiliation, demographics, and clinical, prognostic, and molecular features. Integrated genomics approaches were used to identify specific somatic copy number alterations in TERT promoter-mutated and wild-type tumors. Overall, TERT promoter mutations were identified in 21 % of medulloblastomas. Strikingly, the highest frequencies of TERT mutations were observed in SHH (83 %; 55/66) and WNT (31 %; 4/13) medulloblastomas derived from adult patients. Group 3 and Group 4 harbored this alteration in <5 % of cases and showed no association wit
Artificial recharging of river water: an experiment in Madhya Ganga Canal Project, India
In International Water Management Institute (IWMI); Indian Council of Agricultural Research (ICAR). ICAR-IWMI Ground Water Policy Initiative - 2001, Policy Dialogue on Groundwater Management: papers presented at ICAR-IWMI Workshop on Groundwater Policy Initiative - 2001, Central Soil Salinity Research Institute, Karnal, India, 6-7 November 2001. Karnal India: Central Soil Salinity Research Institut
Using monsoonal river flows to recharge groundwater: an experiment in India
In International Water Management Institute (IWMI). Annual report 2000-2001. Colombo, Sri Lanka: International Water Management Institute (IWMI)