Comparison between Windowed FFT and Hilbert-Huang Transform for Analyzing Time Series with Poissonian Fluctuations: A Case Study

Hilbert-Huang Transform (HHT) is a novel data analysis technique for nonlinear and non-stationary data. We present a time-frequency analysis of both simulated light curves and an X-ray burst from the X-ray burster 4U 1702-429 with both the HHT and the Windowed Fast Fourier Transform (WFFT) methods. Our results show that the HHT method has failed in all cases for light curves with Poissonian fluctuations which are typical for all photon counting instruments used in astronomy, whereas the WFFT method can sensitively detect the periodic signals in the presence of Poissonian fluctuations; the only drawback of the WFFT method is that it cannot detect sharp frequency variations accurately.Comment: 10 pages, 12 figure

Studies on the leptocephali of Bombay waters V. A few other Leptocephali

Leptocephali belonging to the family Murrenidre arc very common in Indian coastal waters as judged by the relatively large member of varieties recorded so far. Including the present form 14 varieties of murrenid leptocephali and 1 murrenid preleptocephalinc stage have been recorded from both the coasts of India

Flux dependent 1.5 MeV self-ion beam induced sputtering from Gold nanostructured thin films

We discuss four important aspects of 1.5 MeV Au2+ ion-induced flux dependent sputtering from gold nanostrcutures (of an average size 7.6 nm and height 6.9 nm) that are deposited on silicon substrates: (a) Au sputtering yield at the ion flux of 6.3x10^12 ions cm-2 s-1 is found to be 312 atoms/ion which is about five times the sputtering yield reported earlier under identical irradiation conditions at a lower beam flux of 10^9 ions cm-2 s-1, (b) the sputtered yield increases with increasing flux at lower fluence and reduces at higher fluence (1.0x10^15 ions cm-2) for nanostructured thin films while the sputtering yield increases with increasing flux and fluence for thick films (27.5 nm Au deposited on Si) (c) Size distribution of sputtered particles has been found to vary with the incident beam flux showing a bimodal distribution at higher flux and (d) the decay exponent obtained from the size distributions of sputtered particles showed an inverse power law dependence ranging from 1.5 to 2.5 as a function of incident beam flux. The exponent values have been compared with existing theoretical models to understand the underlying mechanism. The role of wafer temperature associated with the beam flux has been invoked for a qualitative understanding of the sputtering results in both the nanostructured thin films and thick films.Comment: 25 pages, 5 figures, 1 table To be Appeared in J. Phys. D: Appl. Phy

Unimpeded permeation of water through helium-leak-tight graphene-based membranes

Permeation through nanometer pores is important in the design of materials for filtration and separation techniques and because of unusual fundamental behavior arising at the molecular scale. We found that submicron-thick membranes made from graphene oxide can be completely impermeable to liquids, vapors and gases, including helium, but allow unimpeded permeation of water (H2O permeates through the membranes at least 10^10 times faster than He). We attribute these seemingly incompatible observations to a low-friction flow of a monolayer of water through two dimensional capillaries formed by closely spaced graphene sheets. Diffusion of other molecules is blocked by reversible narrowing of the capillaries in low humidity and/or by their clogging with water

Survey on the idle capacity of fish processing (freezing) plants in India - 2. East coast

The extent of idle capacity in the fish processing (freezing) plants in the east coast of India estimated by stratified random sampling and the factors responsible for the same are reported. The estimates of idle capacity of fish processing plants in the east coast for the years 1978 and 1979 were respectively 75.9% and 72.5% on the basis of 250 working days per annum and double shift per day. The percentage errors of estimates worked out to 6.9 for 1978 and 4.7 for 1979. The corresponding figures were worked out on the basis of 200 working days also. Substantial under-utilisation of plants in all the maritime states in the east coast accounted mainly to non-availability of raw material, high cost of production, shortage of power, scarcity of ice and potable water during peak season and frequent labour troubles

Prawn and fish culture for increased yields

Although culture of marine fish and shell fish in one form or the other has been in existence in different parts of the world from ancient times, yet its progress h as been rather slow till a couple of decades ago. Over the years, accent has been on exploitation of the readily available natural stocks from seas rather than on culture operations

Color Skyrmions in the Quark-Gluon Plasma

We consider the general formulation of nonabelian fluid dynamics based on symmetry considerations. We point out that, quite generally, this admits solitonic excitations which are the color analog of skyrmions. Some general properties of the solitons are discussed.Comment: LaTeX, 13 pages, references adde