Effect of Temperature on the Complexity of Solid Argon System

We study the measure of complexity in solid Argon system from the time series data of kinetic energy of single Argon atoms at different equilibrated temperatures. To account the inherent multi-scale dependence of the complexity, the multi-scale entropy of the time series of kinetic energy of individual Argon atoms are computed at different equilibrated temperatures. The multi-scale entropy study reveals that the dynamics of an atom becomes more complex at higher temperatures and the result corroborates well with the variation of the pair correlation function of the atoms in the solid Argon crystal. Also, we repeat the multi-scale entropy analysis for program generated Levy noise time series and for time series data obtained from the outcomes of exponential decay with noise dx(t) = -x(t) dt + sigma dB(t) (Langevin equation). Our study establishes that the scale dependence of sample entropy for time series of kinetic energy of individual atoms in solid Argon system has similar tendency as that of Levy noise time series and the outcomes of exponential decay with noise (Langevin equation).Comment: 8 pages, 14 figures, Accepted in Indian Journal of Physics for publicatio

Engaging the Canadian Diaspora: Youth social identities in a Canadian border city

This paper is based on qualitative interviews undertaken with immigrant youth of African descent in Windsor, Ontario; it describes their sojourner lives across geographic borders and their final settlement in Windsor. The paper also offers narrations of the activities that enabled them to formulate friendships and the barriers and facilitators to the development of friendships across races. Critical findings reported in this paper reveal the ways that youth use resources in their travels to construct and negotiate their identities and to formulate new friendships. An important resource used by the majority of the youth was that of an imagined homeland, which consequently impacted on how they viewed and acted on the racial boundary critical in the formation of friendships in the Diaspora.Inspiré d’entrevues qualitatives faites auprès de jeunes de descendance africaine établis à Windsor en Ontario, cet article décrit leur périple migratoire à travers les frontières jusqu’à leur établissement en Ontario. Il relate également ce qui les a aidés à bâtir des liens amicaux ainsi que les obstacles et les éléments facilitateurs au développement d’amitiés interraciales. Des résultats importants soulevés dans cet article expliquent les manières dont les jeunes utilisent les ressources au cours du voyage migratoire pour construire et négocier leurs identités et établir de nouvelles amitiés. Il explore comment la majorité des jeunes créent un concept imaginaire de leur mère-patrie, influençant ainsi la façon dont ils perçoivent et agissent sur les frontières raciales fondamentales à la création d’amitiés au sein de la diaspora

Crustal Oscillations of Slowly Rotating Relativistic Stars

We study low-amplitude crustal oscillations of slowly rotating relativistic stars consisting of a central fluid core and an outer thin solid crust. We estimate the effect of rotation on the torsional toroidal modes and on the interfacial and shear spheroidal modes. The results compared against the Newtonian ones for wide range of neutron star models and equations of state.Comment: 15 page

A giant, periodic flare from the soft gamma repeater SGR1900+14

Soft gamma repeaters are high-energy transient sources associated with neutron stars in young supernova remnants. They emit sporadic, short (~ 0.1 s) bursts with soft energy spectra during periods of intense activity. The event of March 5, 1979 was the most intense and the only clearly periodic one to date. Here we report on an even more intense burst on August 27, 1998, from a different soft gamma repeater, which displayed a hard energy spectrum at its peak, and was followed by a ~300 s long tail with a soft energy spectrum and a dramatic 5.16 s period. Its peak and time integrated energy fluxes at Earth are the largest yet observed from any cosmic source. This event was probably initiated by a massive disruption of the neutron star crust, followed by an outflow of energetic particles rotating with the period of the star. Comparison of these two bursts supports the idea that magnetic energy plays an important role, and that such giant flares, while rare, are not unique, and may occur at any time in the neutron star's activity cycle.Comment: Accepted for publication in Natur

Efficiency of the Incomplete Enumeration algorithm for Monte-Carlo simulation of linear and branched polymers

We study the efficiency of the incomplete enumeration algorithm for linear and branched polymers. There is a qualitative difference in the efficiency in these two cases. The average time to generate an independent sample of $n$ sites for large $n$ varies as $n^2$ for linear polymers, but as $exp(c n^{\alpha})$ for branched (undirected and directed) polymers, where $0<\alpha<1$. On the binary tree, our numerical studies for $n$ of order $10^4$ gives $\alpha = 0.333 \pm 0.005$. We argue that $\alpha=1/3$ exactly in this case.Comment: replaced with published versio

Actor based behavioural simulation as an aid for organisational decision making

Decision-making is a critical activity for most of the modern organizations to stay competitive in rapidly changing business environment. Effective organisational decision-making requires deep understanding of various organisational aspects such as its goals, structure, business-as-usual operational processes, environment where it operates, and inherent characteristics of the change drivers that may impact the organisation. The size of a modern organisation, its socio-technical characteristics, inherent uncertainty, volatile operating environment, and prohibitively high cost of the incorrect decisions make decision-making a challenging endeavor. While the enterprise modelling and simulation technologies have evolved into a mature discipline for understanding a range of engineering, defense and control systems, their application in organisational decision-making is considerably low. Current organisational decision-making approaches that are prevalent in practice are largely qualitative. Moreover, they mostly rely on human experts who are often aided with the primitive technologies such as spreadsheets and visual diagrams. This thesis argues that the existing modelling and simulation technologies are neither suitable to represent organisation and decision artifacts in a comprehensive and machine-interpretable form nor do they comprehensively address the analysis needs. An approach that advances the modelling abstraction and analysis machinery for organisational decision-making is proposed. In particular, this thesis proposes a domain specific language to represent relevant aspects of an organisation for decision-making, establishes the relevance of a bottom-up simulation technique as a means for analysis, and introduces a method to utilise the proposed modelling abstraction, analysis technique, and analysis machinery in an effective and convenient manner

Quenched Averages for self-avoiding walks and polygons on deterministic fractals

We study rooted self avoiding polygons and self avoiding walks on deterministic fractal lattices of finite ramification index. Different sites on such lattices are not equivalent, and the number of rooted open walks W_n(S), and rooted self-avoiding polygons P_n(S) of n steps depend on the root S. We use exact recursion equations on the fractal to determine the generating functions for P_n(S), and W_n(S) for an arbitrary point S on the lattice. These are used to compute the averages $, ,$ and $<log W_n(S)>$ over different positions of S. We find that the connectivity constant $\mu$, and the radius of gyration exponent $\nu$ are the same for the annealed and quenched averages. However, $~ n log \mu + (\alpha_q -2) log n$, and $~ n log \mu + (\gamma_q -1)log n$, where the exponents $\alpha_q$ and $\gamma_q$ take values different from the annealed case. These are expressed as the Lyapunov exponents of random product of finite-dimensional matrices. For the 3-simplex lattice, our numerical estimation gives $\alpha_q \simeq 0.72837 \pm 0.00001$; and $\gamma_q \simeq 1.37501 \pm 0.00003$, to be compared with the annealed values $\alpha_a = 0.73421$ and $\gamma_a = 1.37522$.Comment: 17 pages, 10 figures, submitted to Journal of Statistical Physic

Scaling Behaviour and Complexity of the Portevin-Le Chatelier Effect

The plastic deformation of dilute alloys is often accompanied by plastic instabilities due to dynamic strain aging and dislocation interaction. The repeated breakaway of dislocations from and their recapture by solute atoms leads to stress serrations and localized strain in the strain controlled tensile tests, known as the Portevin-Le Chatelier (PLC) effect. In this present work, we analyse the stress time series data of the observed PLC effect in the constant strain rate tensile tests on Al-2.5%Mg alloy for a wide range of strain rates at room temperature. The scaling behaviour of the PLC effect was studied using two complementary scaling analysis methods: the finite variance scaling method and the diffusion entropy analysis. From these analyses we could establish that in the entire span of strain rates, PLC effect showed Levy walk property. Moreover, the multiscale entropy analysis is carried out on the stress time series data observed during the PLC effect to quantify the complexity of the distinct spatiotemporal dynamical regimes. It is shown that for the static type C band, the entropy is very low for all the scales compared to the hopping type B and the propagating type A bands. The results are interpreted considering the time and length scales relevant to the effect.Comment: 35 pages, 6 figure