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Papers by raj ap

Research paper thumbnail of Message from the APS transactions editor's desk

IEEE Antennas and Propagation Magazine, 1983

Research paper thumbnail of Entrance-Channel Effects in the Dynamical Cluster-Decay Model for the Decay of Hot and Rotating Compound Nucleus 48Cr at ECN*≈ 60 MeV

International Journal of Modern Physics E-nuclear Physics, 2006

The entrance-channel effects in the decay of hot and rotating compound nucleus 48Cr*, formed in s... more The entrance-channel effects in the decay of hot and rotating compound nucleus 48Cr*, formed in symmetric 24Mg+24Mg and asymmetric 36Ar+12C reactions, are studied as collective clusterization process, for emissions of both the light particles (LPs) as well as the intermediate mass fragments (IMFs), with in the dynamical cluster-decay model (DCM). We find that the little differences observed in the decay of equilibrated compound nucleus 48Cr*, formed in the two entrance channels with about the same excitation energy, are not in variance with the Bohr's independence hypothesis. In other words, the present study confirms the entrance-channel independence of the decay of compound nucleus 48Cr* formed due to different target-projectile combinations with similar excitation energies. The collective clusterization process is shown to contain the complete structure of the measured fragment cross sections as well as average total kinetic energies.

Research paper thumbnail of Note from the APS transactions editor's desk

IEEE Antennas and Propagation Magazine, 1980

Research paper thumbnail of Inhibition of inducible nitric oxide synthase by sumaflavone isolated from Selaginella tamariscina

Journal of Ethnopharmacology, 2006

The aim of this study was to investigate the involvement of inducible nitric oxide synthase (iNOS... more The aim of this study was to investigate the involvement of inducible nitric oxide synthase (iNOS) in the action of (-)-epigallocatechin-3-gallate (EGCG), a potential neuroprotective agent against Parkinson's disease (PD), and to test for toxicity resulting from high doses of EGCG. EGCG was administered to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice at two different doses (10mg/kg and 50mg/kg). EGCG treatment reduced the neuronal death rate to less than 50%. The level of iNOS expression in the MPTP group was 20% higher than that seen in the control group, but in the EGCG groups, iNOS expression was reduced to the level observed in the negative control group. The two doses of EGCG were equally beneficial for cell rescue, and no toxicity was observed with the higher dose. Inhibition of iNOS may be an important mechanism underlying the prevention of MPTP toxicity, and EGCG may potentially be a neuroprotective agent against PD.

Research paper thumbnail of Modeling of equatorial and low latitude ionosphere over Indian zone

Ionospheric Modeling is important for both scientific and practical purposes. Since the largest v... more Ionospheric Modeling is important for both scientific and practical purposes. Since the largest variability occurs in the ionospheric F-region and for practical HF communication and other applications it would be suffice to model the changes in the F-region parameters of the ionosphere. Ionospheric Electron Content (IEC) is another parameter useful for the determination of phase path, group delay, dispersion, refraction and Faraday polarization rotation of transionospheric signals. In the present study, two HF prediction models for short and long term and one IEC model are developed for equatorial and low latitude ionosphere. Short term HF prediction model is based on Multiple Regression Analysis (MRA) for the dependence of F- region parameters namely foF2 and M(3000)F2, on solar 2800 MHz flux (F10), and geomagnetic index Ap whereas for long term prediction, Second Degree (SD) coefficients are generated by fitting monthly median foF2 and M(3000)F2 with corresponding 12 monthly mean sunspot numbers (R12) using data over three solar cycles. For MRA, daily foF2, M(3000)F2 values for each hour, obtained from Delhi (28.6N, 77.1E) digital ionosonde for about half a solar cycle are used. MRA coefficients, separately for quiet (Ap¡25) and disturbed (Ap˜25) periods, for foF2 and M(3000)F2, are obtained for every month over 24 UT times using daily F10 and Ap values. Whereas SD coefficients are obtained each month at all local times for all the 14 stations covering a geographic latitude range from about 0 to 45N. Similar to SD model, IEC model is also developed using monthly median foF2 and hmF2 values for each hours for all the 14 stations which are feed into IRI 2000 model to calculate respective IEC values for two altitudes namely 1000km and 2000km. Then second degree coefficients, separately for above two altitudes, are obtained for each month at all local times for all the 14 stations. In this way once appropriate coefficients for each hour for all the twelve months are obtained, they are used by the computer based MRA, SD and IEC models, to predict ionospheric hourly foF2, hmF2 and IEC values for a given inputs such as month, F10, Ap and R12 as the case may be. Predicted model values calculated on short and long term basis, are then compared with the observed data and also with those obtained using IRI-2001 model. From the comparative studies, it is observed that MRA and SD models show better agreement with observations as compared to the IRI model for both long as well as short term basis and among the two; the MRA model provides best agreement with the observed ones even during the magnetic storm periods. The SD model on the other hand, which is based on monthly median values, useful for providing long-term predictions for HF communication applications. IEC model predicted results are also gives better agreement with the observed one as compared with those obtained from IRI 2000 model.

Research paper thumbnail of Message from the APS transactions editor's desk

IEEE Antennas and Propagation Magazine, 1983

Research paper thumbnail of Entrance-Channel Effects in the Dynamical Cluster-Decay Model for the Decay of Hot and Rotating Compound Nucleus 48Cr at ECN*≈ 60 MeV

International Journal of Modern Physics E-nuclear Physics, 2006

The entrance-channel effects in the decay of hot and rotating compound nucleus 48Cr*, formed in s... more The entrance-channel effects in the decay of hot and rotating compound nucleus 48Cr*, formed in symmetric 24Mg+24Mg and asymmetric 36Ar+12C reactions, are studied as collective clusterization process, for emissions of both the light particles (LPs) as well as the intermediate mass fragments (IMFs), with in the dynamical cluster-decay model (DCM). We find that the little differences observed in the decay of equilibrated compound nucleus 48Cr*, formed in the two entrance channels with about the same excitation energy, are not in variance with the Bohr's independence hypothesis. In other words, the present study confirms the entrance-channel independence of the decay of compound nucleus 48Cr* formed due to different target-projectile combinations with similar excitation energies. The collective clusterization process is shown to contain the complete structure of the measured fragment cross sections as well as average total kinetic energies.

Research paper thumbnail of Note from the APS transactions editor's desk

IEEE Antennas and Propagation Magazine, 1980

Research paper thumbnail of Inhibition of inducible nitric oxide synthase by sumaflavone isolated from Selaginella tamariscina

Journal of Ethnopharmacology, 2006

The aim of this study was to investigate the involvement of inducible nitric oxide synthase (iNOS... more The aim of this study was to investigate the involvement of inducible nitric oxide synthase (iNOS) in the action of (-)-epigallocatechin-3-gallate (EGCG), a potential neuroprotective agent against Parkinson's disease (PD), and to test for toxicity resulting from high doses of EGCG. EGCG was administered to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mice at two different doses (10mg/kg and 50mg/kg). EGCG treatment reduced the neuronal death rate to less than 50%. The level of iNOS expression in the MPTP group was 20% higher than that seen in the control group, but in the EGCG groups, iNOS expression was reduced to the level observed in the negative control group. The two doses of EGCG were equally beneficial for cell rescue, and no toxicity was observed with the higher dose. Inhibition of iNOS may be an important mechanism underlying the prevention of MPTP toxicity, and EGCG may potentially be a neuroprotective agent against PD.

Research paper thumbnail of Modeling of equatorial and low latitude ionosphere over Indian zone

Ionospheric Modeling is important for both scientific and practical purposes. Since the largest v... more Ionospheric Modeling is important for both scientific and practical purposes. Since the largest variability occurs in the ionospheric F-region and for practical HF communication and other applications it would be suffice to model the changes in the F-region parameters of the ionosphere. Ionospheric Electron Content (IEC) is another parameter useful for the determination of phase path, group delay, dispersion, refraction and Faraday polarization rotation of transionospheric signals. In the present study, two HF prediction models for short and long term and one IEC model are developed for equatorial and low latitude ionosphere. Short term HF prediction model is based on Multiple Regression Analysis (MRA) for the dependence of F- region parameters namely foF2 and M(3000)F2, on solar 2800 MHz flux (F10), and geomagnetic index Ap whereas for long term prediction, Second Degree (SD) coefficients are generated by fitting monthly median foF2 and M(3000)F2 with corresponding 12 monthly mean sunspot numbers (R12) using data over three solar cycles. For MRA, daily foF2, M(3000)F2 values for each hour, obtained from Delhi (28.6N, 77.1E) digital ionosonde for about half a solar cycle are used. MRA coefficients, separately for quiet (Ap¡25) and disturbed (Ap˜25) periods, for foF2 and M(3000)F2, are obtained for every month over 24 UT times using daily F10 and Ap values. Whereas SD coefficients are obtained each month at all local times for all the 14 stations covering a geographic latitude range from about 0 to 45N. Similar to SD model, IEC model is also developed using monthly median foF2 and hmF2 values for each hours for all the 14 stations which are feed into IRI 2000 model to calculate respective IEC values for two altitudes namely 1000km and 2000km. Then second degree coefficients, separately for above two altitudes, are obtained for each month at all local times for all the 14 stations. In this way once appropriate coefficients for each hour for all the twelve months are obtained, they are used by the computer based MRA, SD and IEC models, to predict ionospheric hourly foF2, hmF2 and IEC values for a given inputs such as month, F10, Ap and R12 as the case may be. Predicted model values calculated on short and long term basis, are then compared with the observed data and also with those obtained using IRI-2001 model. From the comparative studies, it is observed that MRA and SD models show better agreement with observations as compared to the IRI model for both long as well as short term basis and among the two; the MRA model provides best agreement with the observed ones even during the magnetic storm periods. The SD model on the other hand, which is based on monthly median values, useful for providing long-term predictions for HF communication applications. IEC model predicted results are also gives better agreement with the observed one as compared with those obtained from IRI 2000 model.