Over-the-Horizon Anomalous VHF Propagation and Earthquake Precursors     

M. Devi  A. K. Barbara  Ya. Yu. Ruzhin  M. Hayakawa 《Surveys in Geophysics》2012,33(5):1081-1106

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Intra-annual variability in nutrients in the Godavari estuary,India     

V.V.S.S. Sarma  V.R. PrasadB.S.K. Kumar  K. RajeevB.M.M. Devi  N.P.C. ReddyV.V. Sarma  M.D. Kumar 《Continental Shelf Research》2010

Daily variations in nutrients were monitored for 15 months (September 2007–November 2008) in the Godavari estuary, Andhra Pradesh, India, at two fixed locations. River discharge has significant influence on nutrients loading to the estuary, which peaks during June–August (peak discharge period; monsoon) whereas exchanges at the sediment–water interface, groundwater and rainwater contribute significantly during other period. Despite significant amount of nutrients brought by discharge to the study region, phytoplankton biomass, in terms of chlorophyll-a (Chl a), did not increase significantly due to high suspended load and shallow photic depth. Nutrients showed downward gradient towards downstream of the estuary from upstream due to dilution by nutrient poor seawater and biological uptake. The N:P ratios were higher than Redfield ratio in both upstream and downstream of the estuary during no discharge period suggesting PO₄ to be a limiting nutrient for phytoplankton production, at levels <0.10 μmol L⁻¹. On the other hand, Si:N ratios were always more than unity during entire study period at both the stations indicating that Si(OH)₄ is not a limiting nutrient. Our results suggest that suspended matter limits phytoplankton biomass during peak discharge period whereas PO₄ during no discharge period.  相似文献   

Geochemistry of mid-ocean ridge mafic intrusives from the Manipur Ophiolitic Complex,Indo-Myanmar Orogenic Belt,NE India     

A. Krishnakanta Singh  N. Ibotombi Singh  L. Debala Devi  R. K. Bikramaditya Singh 《Journal of the Geological Society of India》2012,80(2):231-240

Mafic intrusives emplaced within the mélange zone of the Manipur Ophiolitic Complex are subalkalinetholeiitic affinity with Fe-enrichment. Based on the field occurrences, textures-mineralogy and whole-rock compositions, these mafic intrusives can be identified as type-I (gabbro intrusives) and type-II (basalt-dolerite dykes). The type-I resembling enriched-type mid-ocean ridge basalt (E-MORB) shows moderate LREE enrichment (La_N/Sm_N = 2.5–2.6), slightly enriched MORB normalized HFSE patterns possibly represent melts derived from enriched MORB sub-oceanic mantle sources by small degree of partial melting. The other type-II has normal-type mid-ocean ridge basalt (N-MORB) geochemical features, as it exhibits nearly flat to depleted LREE (La_N/Sm_N = 1.0–0.6), flat MORB normalized HFSE patterns with slight LREE/HREE depletion (Ce_N/Yb_N = 1.37–0.46). It might have been derived from depleted MORB type sub-oceanic mantle source. The MORB signature displayed by these mafic intrusives indicates that they are dismembered fragments of oceanic crust generated at mid-ocean spreading ridge system and support the hypothesis that the Manipur ophiolites was initially formed in the divergent plate margin.  相似文献   

Lower Oligocene bivalves of Ramanian Stage from Kachchh, Gujarat, India     

R P Kachhara  R L Jodhawat  K Bigyapati Devi 《Journal of Earth System Science》2012,121(2):405-438

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Particle creation with time dependent gravitational and cosmological constants     

N. Ibotombi Singh  Y. Bembem Devi  S. Surendra Singh 《Astrophysics and Space Science》2013,345(1):213-216

The effect of particle creation on the evolution of FRW cosmological model has been studied. The universe has been considered as an open thermodynamic system when particle creation leads to supplementary negative creation pressure in addition to the thermodynamic pressure. Dynamical behaviors of the cosmological solutions have been studied.  相似文献   

Anisotropic universe with cosmic strings and bulk viscosity in a scalar–tensor theory of gravitation     

V. U. M. Rao  G. Sree Devi Kumari  K. V. S. Sireesha 《Astrophysics and Space Science》2011,335(2):635-638

A spatially homogeneous and anisotropic Bianchi type-I cosmological model is obtained in a scalar–tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. A 113:467, 1986) when the source for energy momentum tensor is a bulk viscous fluid containing one dimensional cosmic strings. Some physical and kinematical properties of the model are discussed. It is observed that the bulk viscosity has a greater role in getting an accelerated expansion of the universe in this theory.  相似文献