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Dehradun, India

Kumar S.,Rd University | Raizada A.,DAV PG College
Planetary and Space Science | Year: 2010

Highly variable conditions prevail in the geospace environment due to the variations in Solar activity. The characteristics of the magnetic clouds (MCs) and their effects on geosphere, which have occurred during the period January 1996 to December 2006; have been investigated. No systematic trend has been observed between MCs and Solar activity cycle which is analyzed on the basis of maximum Sunspot number in that particular year. 85% MCs are found to be geoeffective. MCs are divided into two major classes: unipolar and bipolar. Unipolar MCs are of south (S) or north (N) type while bipolar MCs are of south-north (SN) or north-south (NS) type. During Solar cycle 23, SN-type MCs dominated over NS-type MCs. Highly intense geomagnetic storms (GMSs) of Dst <-300 nT follow from SN or S-type MCs. No preference is observed for right handed (RH) or left handed (LH) clouds for being geoeffective. MCs of very high speed lead to intense GMSs. The correlation coefficient (r) of southward component of magnetic field (Bz), total magnetic field (B) and their products with plasma flow speed (VB and VBz) with Dst are observed to be r=0.78, -0.81, -0.79 and 0.82, respectively, which suggests that these parameters are reliable indicators of the strength of GMS. SN clouds do not always lead to more fall in Dst value (or lead to high strength of GMS) than NS clouds for similar value of Bz minimum associated with both type of MCs. © 2009 Elsevier Ltd. All rights reserved. Source


Pandey A.K.,Gorakhpur University | Mohan M.,DAV PG College | Singh P.,Gorakhpur University | Palni U.T.,Kumaun University | Tripathi N.N.,Gorakhpur University
Food Bioscience | Year: 2014

In the present laboratory bioassay, antibacterial activity of 22 Asteraceae essential oils were evaluated against two phytopathogenic bacteria Erwinia herbicola (Lohnis) and Pseudomonas putida (Kris Hamilton). Of 22 oils, Eupatorium adenophorum Spreng oil exhibited highest toxicity against both bacteria followed by Artemisia nilagirica Linn., Blumea eriantha DC., Blumea lacera (Burm.f.) DC and Tagetes erecta Linn oils. During MIC and MBC determination, E. adenophorum oil displayed its superiority over the other four toxic oils as well as antibiotics (agromycin and streptomycin) with MIC and MBC values ranges of 0.25-4.0 μl ml-1 for both bacterial species. GC and GC-MS analysis of E. adenophorum oil revealed that the oil was mixture of 35 major and minor components. Among these components, acoradiene (10.11%), bornyl acetate (10.60%), camphene (12.05%), p-cymene (11.6%) and α-phellandrene (8.57%) represent higher percent composition. E. adenophorum oil showed potent antioxidant activity and IC50 values were 8.3 and 4.2 μl, when tested by DPPH and β-carotene bleaching methods, respectively. The findings concluded that E. adenophorum oil may be supplemented as potent antibacterial and antioxidant agent in food and pharmaceutical systems. © 2014 Elsevier Ltd. Source


Purohit G.,DAV PG College | Sharma P.,NSCB Government Postgraduate College | Sharma R.P.,Indian Institute of Technology Delhi
Journal of Plasma Physics | Year: 2012

This paper presents the effect of laser beam filamentation on the localization of electron plasma wave (EPW) and stimulated Raman scattering (SRS) in unmagnetized plasma when relativistic and ponderomotive nonlinearities are operative. The splitted profile of the laser beam is obtained due to uneven focusing of the off-axial rays. The semi-analytical solution of the nonlinearly coupled EPW equation in the presence of laser beam filaments has been found. It is observed that due to this nonlinear coupling between these two waves, localization of EPW takes place. Stimulated Raman scattering of this EPW is studied and back reflectivity has been calculated. Further, the localization of EPW affects the eigenfrequency and damping of plasma wave. The new enhanced damping of the plasma wave has been calculated and it is found that the SRS process gets suppressed due to the localization of plasma wave in laser beam filamentary structures. © Copyright Cambridge University Press 2011. Source


Diduck A.P.,University of Winnipeg | Pratap D.,DAV PG College | Sinclair A.J.,University of Manitoba | Deane S.,University of Winnipeg
Land Use Policy | Year: 2013

The hydropower potential of the state of Uttarakhand, in the Indian Himalaya, is an estimated 20,000. MW, of which approximately 3200. MW have been developed. In conjunction with the central government, Uttarakhand is pursuing a policy of rapidly developing its remaining potential. The necessity for careful planning, assessment and mitigation of this development is paramount, requiring meaningful and effective public participation. This study examined two hydropower projects in Chamoli District. Our purpose was to investigate how stakeholders viewed the projects' impacts, how local residents were involved in planning, assessment and mitigation, and what the residents learned from their involvement. We used a qualitative methodology involving a document review, participant observation, and semi-directed interviews. Local residents and nongovernmental organizations emphasized adverse social and environmental impacts. They thought the way of life and social fabric of affected villages were significantly altered and future sustainability was uncertain. Industry respondents emphasized the economic benefits. Government officials were relatively balanced in their perceptions. In one project, the only formal participation opportunity occurred during mitigation: development of the catchment area treatment plan. In the other, opportunities were available during assessment (e.g., hearings) and mitigation (e.g., advisory committees). Both projects involved multiple informal efforts at participation (e.g., legal petitions and public protests). Among local residents, there were notable instances of sustainability-oriented learning. The development of hydropower projects in Uttarakhand can become more participative, to improve decision making, promote equity, and create opportunities for sustainability learning. © 2013 Elsevier Ltd. Source


Purohit G.,DAV PG College | Sharma P.,Indian Institute of Technology Delhi | Sharma R.P.,Indian Institute of Technology Delhi
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2010

This Letter presents an investigation of the excitation of an upper hybrid wave (UHW) by cross focusing of two intense laser beams in a collisionless hot magnetoplasma, when relativistic and ponderomotive nonlinearities are operative. The electric vectors of the two beams are polarized along uniform static magnetic field and the beams propagate perpendicular to the static magnetic field. Analytical expressions for the beam width of the laser beams, electric vector and power of the excited UHW and energy gain have been obtained. The UHW generation at the difference frequency and particle acceleration has also been studied. The nonlinear coupling between intense laser beams and UHW is so strong that UHW gets excited and a large fraction of the laser beam energy gets transferred to UHW and this UHW accelerates electrons. It has been shown that the presence of a magnetic field affects significantly the power of the UHW and energy gain by the electron in the presence of the UHW. © 2009 Elsevier B.V. All rights reserved. Source

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