Detection of hidden structures on all scales in amorphous materials and complex physical systems: basic notions and applications to networks, lattice systems, and glasses

Recent decades have seen the discovery of numerous complex materials. At the root of the complexity underlying many of these materials lies a large number of possible contending atomic- and larger-scale configurations and the intricate correlations between their constituents. For a detailed understanding, there is a need for tools that enable the detection of pertinent structures on all spatial and temporal scales. Towards this end, we suggest a new method by invoking ideas from network analysis and information theory. Our method efficiently identifies basic unit cells and topological defects in systems with low disorder and may analyze general amorphous structures to identify candidate natural structures where a clear definition of order is lacking. This general unbiased detection of physical structure does not require a guess as to which of the system properties should be deemed as important and may constitute a natural point of departure for further analysis. The method applies to both static and dynamic systems.Comment: (23 pages, 9 figures

Preparation of long aligned carbon nanotubes and study its physical properties

Carbon nanotubes (CNTs) of about 6 µm long have been successfully prepared by a simple pyrolysis technique. The precursors used for the synthesis of nanotubes through pyrolysis technique are pyridine (carbon source material) and ferrocene (catalyst). The synthesized CNTs have been characterized by X-ray Diffraction (XRD), field-emission scanning electron microscopy (FESEM) and High-resolution Transmission Electron Microscopy (TEM) and Raman Spectroscopy. The aligned carbon nanotubes were dissolved in polymethyl methacrylate (PMMA) polymer in a solution and silver contacts were made to study the effect of CNTs on electrical properties of PMMA. The I-V characterization of the PMMA-CNTs was performed to study its electrical properties. A linear current-voltage characteristic was obtained. The change in resistance with and without diffusion of polymer in carbon nanotubes were calculated from the I-V curve

Neutrino Emissivity of Dense Stars

The neutrino emissivity of compact stars is investigated in this work. We consider stars consisting of nuclear as well as quark matter for this purpose. Different models are used to calculate the composition of nuclear and quark matter and the neutrino emissivity. Depending on the model under consideration, the neutrino emissivity of nuclear as well as quark matter varies over a wide range. We find that for nuclear matter, the direct URCA processes are allowed for most of the relativistic models without and with strange baryons, whereas for the nonrelativistic models this shows a strong dependence on the type of nuclear interaction employed. When the direct URCA processes are allowed, the neutrino emissivity of hadronic matter is larger than that of the quark matter by several orders of magnitude. We also find that the neutrino emissivity departs from $T^6$ behavior when the temperature is larger than the difference in the Fermi momenta of the particles, participating in the neutrino-producing reactions.Comment: Latex file. 5 figures available on request. accepted in Int. J. Mod. Phys.

Design and fabrication of a data logger for atmospheric pressure, temperature and relative humidity for gas-filled detector development

A novel instrument has been developed to monitor and record the ambient pa- rameters such as temperature, atmospheric pressure and relative humidity. These parameters are very essential for understanding the characteristics such as gain of gas filled detectors like Gas Electron Multiplier (GEM) and Multi Wire Propor- tional Counter (MWPC). In this article the details of the design, fabrication and operation processes of the device has been presented.Comment: 11 pages, 12 figure

A new skew-elliptical distribution and its properties

This article generalizes a multivariate skew-elliptical distribution and describes its many interesting properties. The univariate version of the new distribution is compared with two other currently used distributions. The use of the new distribution is illustrated with a real data example suitable for regression modelling. The new model provides a better model fit than its two rivals as evaluated by some suitable Bayesian model selection criteria