Characterization of VHF radar observations associated with equatorial Spread F by narrow-band optical measurements

International audienceThe VHF radars have been extensively used to investigate the structures and dynamics of equatorial Spread F (ESF) irregularities. However, unambiguous identification of the nature of the structures in terms of plasma depletion or enhancement requires another technique, as the return echo measured by VHF radar is proportional to the square of the electron density fluctuations. In order to address this issue, co-ordinated radar backscatter and thermospheric airglow intensity measurements were carried out during March 2003 from the MST radar site at Gadanki. Temporal variations of 630.0-nm and 777.4-nm emission intensities reveal small-scale ("micro") and large-scale ("macro") variations during the period of observation. The micro variations are absent on non-ESF nights while the macro variations are present on both ESF and non-ESF nights. In addition to the well-known anti-correlation between the base height of the F-region and the nocturnal variation of thermospheric airglow intensities, the variation of the base height of the F-layer, on occasion, is found to manifest as a bottomside wave-like structure, as seen by VHF radar on an ESF night. The micro variations in the airglow intensities are associated with large-scale irregular plasma structures and found to be in correspondence with the "plume" structures obtained by VHF radar. In addition to the commonly observed depletions with upward movement, the observation unequivocally reveals the presence of plasma enhancements which move downwards. The observation of enhancement in 777.4-nm airglow intensity, which is characterized as plasma enhancement, provides an experimental verification of the earlier prediction based on numerical modeling studies

Evaluation of anti-tumor activity of ethanolic extract of Glycyrrhiza glabra against Ehrlich ascites carcinoma in swiss albino mice

Background: Cancer is one of the most life threatening diseases which is in need of newer drug development. The use of plant products with potent antioxidant and cytotoxic activity is upcoming Studies reveal that herbal product have increased efficacy as well as decreased side effects, with this in mind the present study was undertaken to assess the antitumor activity of extracts of Glycyrrhiza glabra (GG) against ehrlich ascites carcinoma in swiss albino mice.Methods: The extracts of roots of GG was collected and acute toxicity study was done following which the antitumor effect of extracts of GG was assessed by change in the body weight, mean survival time (MST), and percentage increased life span (% ILS). MST of each group containing six mice was monitored by recording the mortality daily for 6 weeks and % ILS was calculated. The hematological parameters and biochemical assays were also measured.Results: Extracts of GG showed a significant reduction in % increase in tumor induced body weight of the mice. The % increase in life span was also significant in the higher dose of GG (500 mg/kg). The combination of GG with standard drug cisplatin had better efficacy in terms of % ILS, hematological and biochemical parameters. The results obtained were statistically significant.Conclusions: The antitumor activity studies measuring the viability of cancer cells when exposed to the ethanolic extract of Glycyrrhiza glabra showed a potent cell-killing effect, indicating the presence of anti-cancer principles in the preparation

Early Proterozoic Melt Generation Processes beneath the Intra-cratonic Cuddapah Basin, Southern India

Early Proterozoic tholeiitic lavas and sills were emplaced during the initial phase of extension of the intra-cratonic Cuddapah Basin, Southern India. 40Ar-39Ar laser-fusion determinations on phlogopite mica, from the Tadpatri Fm mafic-ultramafic sill complex, constrain the age of the initial phase of extension and volcanism in the basin at 1·9Ga. Despite their Early Proterozoic age, the igneous rocks are unmetamorphosed, undeformed and remarkably fresh. They exhibit a wide range in MgO contents (4-28wt%) and have undergone varying degrees of accumulation or crystal fractionation. Variable La/Nb ratios (1·2-3·7) and εNd values (1 to -10) suggest that some, but not all, of the mafic rocks have been affected by crustal contamination. This appears to have taken place in magma chambers at ~9kbar, i.e. the base of the continental crust. Forward modelling of major and trace elements (Fe and Nd) and inverse modelling of rare earth elements suggest that the primary Cuddapah melts were generated by ~10-15% partial melting of a lherzolite mantle source. This corresponds to a mantle potential temperature of ~1500°C. The thickness of the mechanical boundary layer predicted by the geochemical modelling is 70km with a minimum initial lithospheric thickness of 120km. This corresponds to a stretching factor of 1·6-1·8. Richter's (1988) secular cooling model for the Earth predicts that, at 1·9Ga, the ambient mantle had a potential temperature of ~1500°C (i.e. ~200°C hotter than Phanerozoic mantle). If the cooling model is correct then Proterozoic lithospheric stretching and mantle melting beneath the intra-cratonic Cuddapah Basin could have been caused by passive rather than active rifting

Characterizations of the diurnal shapes of OI 630.0 nm dayglow intensity variations: inferences

International audienceMeasurements of OI 630.0 nm thermospheric dayglow emission by means of the Dayglow Photometer (DGP) at Mt. Abu (24.6° N, 73.7° E, dip lat 19.09° N), a station under the crest of Equatorial Ionization Anomaly (EIA), reveal day-to-day changes in the shapes of the diurnal profiles of dayglow intensity variations. These shapes have been characterized using the magnetometer data from equatorial and low-latitude stations. Substantial changes have been noticed in the shapes of the dayglow intensity variations between 10:00?15:00 IST (Indian Standard Time) during the days when normal and counter electrojet events are present over the equator. It is found that the width (the time span corresponding to 0.8 times the maximum dayglow intensity) of the diurnal profile has a linear relationship with the integrated electrojet strength. Occasional deviation from this linear relationship is attributed to the presence of substantial mean meridional wind