Physics
https://repository.iitgn.ac.in/handle/123456789/607
Tue, 26 Mar 2019 15:17:41 GMT2019-03-26T15:17:41ZPrediction of the disease controllability in a complex network using machine learning algorithms
https://repository.iitgn.ac.in/handle/123456789/4288
Prediction of the disease controllability in a complex network using machine learning algorithms
Tripathi, Richa; Reza, Amit; Garg, Dinesh
The application of machine learning (ML) techniques spans a vast spectrum of applications ranging from speech, face and character recognition to medical diagnosis to anomaly detection in data and the general classification, prediction and regression problems. In the present work, we demonstrate the application of regression-based state-of-art machine learning techniques to a prediction of disease controllability on complex networks. The complex network models determine the space for distribution of a population of individuals and their interactions with each other. There is numerous epidemic spreading models such as SI (Susceptible-Infected), SIR (Susceptible-Infected-Recovered), SEIR (Susceptible-Exposed-Infected-Recovered), etc., that govern the disease spreading dynamics over time and the stationary state of the disease. We simulate the disease spreading dynamics on a large number of complex networks examples of standard model networks, and determine the basic reproduction number (R 0 ) for each case. R_0 is a metric that determines whether the disease-free epidemic or an endemic state is asymptotically stable. In other words, it determines whether an infectious disease can spread in the population or will die out in the long run and hence indicates the disease controllability on a population. We aim to predict this quantity (R 0 ), based on the importance of complex networks structural properties using the regression techniques of ML, irrespective of the network type. The prediction is possible because of two facts (a) The structure of complex networks plays an essential role in the spreading processes on networks. (b) Availability of non-linear regression techniques with excellent accuracy for prediction of a quantity even for a data which is highly non-linear.
Fri, 01 Feb 2019 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/42882019-02-01T00:00:00ZFirst order dissipative hydrodynamics from an effective covariant kinetic theory
https://repository.iitgn.ac.in/handle/123456789/4285
First order dissipative hydrodynamics from an effective covariant kinetic theory
Bhadury, Samapan; Kurian, Manu; Chandra, Vinod; Jaiswal, Amaresh
The probability densities of work that can be exerted on a quantum system initially staying in thermal equilibrium are constrained by the fluctuation relations of Jarzynski and Crooks, when the work is determined by two projective energy measurements. We investigate the question whether these fluctuation relations may still hold if one employs generalized energy measurements rather than projective ones. Restricting ourselves to a class of universal measurements which are independent of several details of the system on which the work is done, we find sets of necessary and sufficient conditions for the Jarzynski equality and the Crooks relation. The Jarzynski equality requires the perfect accuracy for the initial measurement, while the final one can be erroneous. On the other hand, the Crooks relation can only tolerate a depolarizing channel as a deviation from the projective measurement for systems with a finite dimensional Hilbert space. For a separable infinite-dimensional space only projective measurements are compatible with the Crooks relation. The results we have obtained significantly extend those in [B. P. Venkatesh, G. Watanabe, and P. Talkner, New J. Phys. 16, 015032 (2014)] as well as avoid some errors present there.
Fri, 01 Feb 2019 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/42852019-02-01T00:00:00ZNarrow-band search for gravitational waves from known pulsars using the second LIGO observing run
https://repository.iitgn.ac.in/handle/123456789/4287
Narrow-band search for gravitational waves from known pulsars using the second LIGO observing run
Sengupta, Anand
Isolated spinning neutron stars, asymmetric with respect to their rotation axis, are expected to be sources of continuous gravitational waves. The most sensitive searches for these sources are based on accurate matched filtering techniques, that assume the continuous wave to be phase-locked with the pulsar beamed emission. While matched filtering maximizes the search sensitivity, a significant signal-to-noise ratio loss will happen in case of a mismatch between the assumed and the true signal phase evolution. Narrow-band algorithms allow for a small mismatch in the frequency and spin-down values of the pulsar while integrating coherently the entire data set. In this paper we describe a narrow-band search using LIGO O2 data for the continuous wave emission of 33 pulsars. No evidence for a continuous wave signal has been found and upper-limits on the gravitational wave amplitude, over the analyzed frequency and spin-down volume, have been computed for each of the targets. In this search we have surpassed the spin-down limit for some of the pulsars already present in the O1 LIGO narrow-band search, such as J1400\textminus6325 J1813\textminus1246, J1833\textminus1034, J1952+3252, and for new targets such as J0940\textminus5428 and J1747\textminus2809. For J1400\textminus6325, J1833\textminus1034 and J1747\textminus2809 this is the first time the spin-down limit is surpassed.
Fri, 01 Feb 2019 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/42872019-02-01T00:00:00ZLongitudinal conductivity of hot magnetized collisional QCD medium in the inhomogeneous electric field
https://repository.iitgn.ac.in/handle/123456789/4286
Longitudinal conductivity of hot magnetized collisional QCD medium in the inhomogeneous electric field
Kurian, Manu; Chandra, Vinod
The longitudinal current density induced by the inhomogeneous electric field in the hot magnetized quark-gluon plasma has been investigated and utilized in obtaining the conductivity of the medium. The analysis has been done in the regime where inhomogeneity of the field is small so that the collision effect could be significant. The modeling of the QCD medium is based on a quasiparticle description where the medium effects have been encoded in the effective quarks, antiquarks and gluons. The temperature dependence of the linear longitudinal current density (in terms of the electric field) and the additional components of current density due to the inhomogeneity of electric field (in terms of its derivatives) have been obtained by solving the�(1+1)?dimensional effective covariant kinetic theory with a proper collision term. The conductivity has been obtained from the current density in the presence of the inhomogeneous field. The collisional aspects of the medium have been captured by including both thermal relaxation approximation and the Bhatnagar-Gross-Krook collision kernels in the analysis. Further, the hot QCD medium effects and higher Landau level contributions to the current density and the conductivity have been investigated. It has been seen that the effects of inhomogeneity of the field and the mean field corrections to the current density and the conductivity are more visible in the temperature regions which are not far from the transition temperature.
Fri, 01 Feb 2019 00:00:00 GMThttps://repository.iitgn.ac.in/handle/123456789/42862019-02-01T00:00:00Z