781 research outputs found
Lamb Wave Modes in Coal-Tar-Coated Steel Plates
In order to study the feasibility of using ultrasonic Lamb wave modes for detection and sizing of corrosion-related flaws in buried steel pipelines, we have calculated Lamb wave modes and performed numerous experiments on steel plates coated on one side with coal-tar enamel. The purpose of this paper is to discuss these theoretical and experimental results
Theory of Adiabatic fluctuations : third-order noise
We consider the response of a dynamical system driven by external adiabatic
fluctuations. Based on the `adiabatic following approximation' we have made a
systematic separation of time-scales to carry out an expansion in , where is the strength of fluctuations and is the
damping rate. We show that probability distribution functions obey the
differential equations of motion which contain third order terms (beyond the
usual Fokker-Planck terms) leading to non-Gaussian noise. The problem of
adiabatic fluctuations in velocity space which is the counterpart of Brownian
motion for fast fluctuations, has been solved exactly. The characteristic
function and the associated probability distribution function are shown to be
of stable form. The linear dissipation leads to a steady state which is stable
and the variances and higher moments are shown to be finite.Comment: Plain Latex, no figures, 28 pages; to appear in J. Phys.
Dynamics of a metastable state nonlinearly coupled to a heat bath driven by an external noise
Based on a system-reservoir model, where the system is nonlinearly coupled to
a heat bath and the heat bath is modulated by an external stationary Gaussian
noise, we derive the generalized Langevin equation with space dependent
friction and multiplicative noise and construct the corresponding Fokker-Planck
equation, valid for short correlation time, with space dependent diffusion
coefficient to study the escape rate from a metastable state in the moderate to
large damping regime. By considering the dynamics in a model cubic potential we
analyze the result numerically which are in good agreement with the theoretical
prediction. It has been shown numerically that the enhancement of rate is
possible by properly tuning the correlation time of the external noise.Comment: 13 pages, 5 figures, Revtex4. To appear in Physical Review
Strange matter in rotating compact stars
We have constructed equations of state involving various exotic forms of
matter with large strangeness fraction such as hyperon matter, Bose-Einstein
condensates of antikaons and strange quark matter. First order phase
transitions from hadronic to antikaon condensed and quark matter are considered
here. The hadronic phase is described by the relativistic field theoretical
model. Later those equations of state are exploited to investigate models of
uniformly rotating compact stars. The effect of rotation on the third family
branch for the equation of state involving only antikaon condensates is
investigated. We also discuss the back bending phenomenon due to a first order
phase transition from condensed to quark matter.Comment: 8 pages, 4 figures; Plenary talk delivered at Strangeness in Quark
Matter (SQM) 2004 held in Cape Town, South Africa from 15-20 September;
Accepted for publication in the proceedings in Journal of Physics
Magnolol: A neolignan from the Magnolia family for the prevention and treatment of cancer
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. The past few decades have witnessed widespread research to challenge carcinogenesis; however, it remains one of the most important health concerns with the worst prognosis and diagnosis. Increasing lines of evidence clearly show that the rate of cancer incidence will increase in future and will create global havoc, designating it as an epidemic. Conventional chemotherapeutics and treatment with synthetic disciplines are often associated with adverse side effects and development of chemoresistance. Thus, discovering novel economic and patient friendly drugs that are safe and efficacious is warranted. Several natural compounds have proved their potential against this dreadful disease so far. Magnolol is a hydroxylated biphenyl isolated from the root and stem bark of Magnolia tree. Magnolol can efficiently prevent or inhibit the growth of various cancers originating from different organs such as brain, breast, cervical, colon, liver, lung, prostate, skin, etc. Considering these perspectives, the current review primarily focuses on the fascinating role of magnolol against various types of cancers, and the source and chemistry of magnolol and the molecular mechanism underlying the targets of magnolol are discussed. This review proposes magnolol as a suitable candidate that can be appropriately designed and established into a potent anti-cancer drug
Exotic bulk viscosity and its influence on neutron star r-modes
We investigate the effect of exotic matter in particular, hyperon matter on
neutron star properties such as equation of state (EoS), mass-radius
relationship and bulk viscosity. Here we construct equations of state within
the framework of a relativistic field theoretical model. As hyperons are
produced abundantly in dense matter, hyperon-hyperon interaction becomes
important and is included in this model. Hyperon-hyperon interaction gives rise
to a softer EoS which results in a smaller maximum mass neutron star compared
with the case without the interaction. Next we compute the coefficient of bulk
viscosity and the corresponding damping time scale due to the non-leptonic weak
process including hyperons. Further, we investigate the role of the
bulk viscosity on gravitational radiation driven r-mode instability in a
neutron star of given mass and temperature and find that the instability is
effectively suppressed.Comment: 5 pages, 3 figure, presented in the Conference on Isolated Neutron
Stars: From the Interior to The Surface, London, UK, 24-28 April, 2006;
revised and final version to appear in Astrophys. Space Sc
- …