http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/482 Sun, 26 May 2013 01:28:44 GMT 2013-05-26T01:28:44Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2706 Nonlinear Analysis of an Electroencephalogram (ECG) During Epileptic Seizure Lalaja, Varghese; V P N Nampoori; Pratap, R A mathematical analysis of an electroencephalogram of a human Brain during an epileptic seizure shows that the K2 entropy decreases as compared to a clinically normal brain while the dimension of the attractor does not show significant deviation. Tue, 20 Oct 1987 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2706 1987-10-20T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2656 Photoacoustic study of the effect of hydroxyl ion on thermal diffusivity of γ alumina Sankara Raman, S; Nampoori, V P N; Vallabhan, C P G; Ambadas, G; Sugunan, S The effect of the chemisorbed hydroxyl groups on the thermal diffusivity of gama alumina is determined by evaluating the thermal diffusivity at various degassing temperatures and by doping it with rare earth oxide using photoacoustic technique. The thermal diffusivity is found to decrease with the increase in degassing temperature as well as with the increase in the doping concentration of rare earth oxide. This decrease has been attributed to the loss of hydroxyl ion from the y-Al2O3. Mon, 01 Feb 1999 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2656 1999-02-01T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2654 Excitation and Emission Characteristics of Pretreated SrS:Mn:Ce Phosphors Lalitha, P R; Rao, V R; V P N Nampoori Excitation and emission spectra of SrS : Mn : Ce phosphors have been studied in detail at various Mn and Ce concentrations. In order to study the effect of external pressure on phosphors, the samples were pretreated under various pressures. Four bands around 470 nm, 530 nm, 310 nm and 620 nm were observed, when the samples were excited with 265 nm radiation. The effect of pressure is to reduce the fluorescence ability of the phosphors, and the luminescence vanishes above O· 1 ton m-2 pressure. The fluorescence ability, however, can be regained on retiring the sample. The emission mechanism has been attributed to two luminescentcenters in the forbidden gap. An appreciable amount of photocurrent has also been observed for the sample. Tue, 01 Jan 1980 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2654 1980-01-01T00:00:00Z http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2653 Significance of Time Scales in Nonlinear Dynamical Analysis of Electroencephalogram Signals Indic, P; Pratap, R; Nampoori, V P N; Pradhan, N We propose to show in this paper, that the time series obtained from biological systems such as human brain are invariably nonstationary because of different time scales involved in the dynamical process. This makes the invariant parameters time dependent. We made a global analysis of the EEG data obtained from the eight locations on the skull space and studied simultaneously the dynamical characteristics from various parts of the brain. We have proved that the dynamical parameters are sensitive to the time scales and hence in the study of brain one must identify all relevant time scales involved in the process to get an insight in the working of brain. Fri, 01 Jan 1999 00:00:00 GMT http://dyuthi.cusat.ac.in:80/xmlui/handle/purl/2653 1999-01-01T00:00:00Z