33 research outputs found

    Seasonal march of surface pressure gradients across India and the southwest monsoon

    No full text
    It is well known that the seasonal weather features of Indian sub-continent are associated with corresponding changes in the pressure gradients across the country

    Effect of 50% hydro-ethanolic leaf extracts of ruellia tuberosa L. and dipteracanthus patulus (Jacq.) on lipid profile in alloxan induced diabetic rats

    No full text
    Background: The study was undertaken to investigate the effect of 50% hydro -ethanolic leaf extracts of Ruellia tuberosa L. and Dipteracanthus patulus (Jacq.) on lipid profile in alloxan induced diabetic rats. Method: In lipid profile the parameters studied were serum total cholesterol, phospholipids, triglycerides, HDL-c, LDL-c and VLDL-c level. Extracts were orally administered daily for 30 days at a dosage of 250 and 500 mg/kg bodyweight to alloxan induced diabetic rats. Results: The levels of phospholipids, triglycerides, LDL-c and VLDL-c were significantly (P < 0.05) reduced. The HDL-c level was found to be increased in the treatment groups. Total cholesterol level was found to be significantly (P < 0.05) decreased at 500 mg/kg bodyweight of both the plant extracts treated groups. Conclusion: The results further suggests that the effect of plant extract treated groups was found to be lower in reducing the lipid levels in serum when compared to the drug (Glibenclamide 600 ΅g/kg body weight) treated group

    Concentration in Knowledge Output: A case of Economics Journals

    No full text
    This paper assesses the degree of author concentration in seven economics journals, which were published in India during 1990-2002. To measure the degree of author concentration, Lotka's Law was used. Moreover, we also make an exploratory analysis of the geographic, economics subfield and institutional concentration in 704 economics journals. An important finding of this paper is that specialized journals in the sample report the highest degree of author concentration. This result is quite similar to the findings by Cox and Chung (1991). Furthermore, there are several instances showing that the journals lean towards certain norms; this may affect the flow of innovative ideas into economics. We conclude that a knowledge activity, involving the high degree of concentration and a biased publication process, may affect the flow of new ideas into the discipline.Concentration, Lotka's Law

    Optimization of Solar Sailcraft Trajectory for a Comet Sample Return Mission

    No full text
    Comets, the sporadic visitors from the outer edges of the Solar System, are considered to hold the key for understanding the formation of planets and the origin of life on Earth. Having spent the majority of time away from the radiative environment of the inner Solar System, the chemistry of the comets has remained unaltered, making them the pristine samples of the matter from the ancient Solar nebula. A mission to bring cometary particles back to Earth enables the examination of the materials in well equipped laboratories and saves the mass of the instruments to be carried on board. As conventional propulsion methods require a large quantity of propellant for this type of mission, the feasibility of using the novel propulsion technique of solar sailing is explored in this thesis. In order to return the comet samples to Earth within a reasonable time period, the orbit transfer is considered as an optimal control problem with constraints placed on the sailcraft’s position and velocity. The Differential Evolution (DE) algorithm was used to search for time-optimal trajectories that minimize the approach distance and the relative velocity with respect to the comet during sample collection. The optimal trajectory obtained predicts the solar sailcraft to reach the comet, collect the samples and return back to Earth in 6.8 years. The time of arrival at the comet was found to match with the comet's perihelion passage, enabling effective sample collection. The outcome of the trajectory analysis, thus successfully demonstrates the applicability of solar sailing to comet sample return missions in the near future.Aerospace Engineering | Astrodynamics & Space Mission
    corecore