VLA observations of extreme hydrogen deficient stars     

N. Kameswara Rao  V. R. Venugopal  A. Patnaik 《Journal of Astrophysics and Astronomy》1985,6(3):153-157

VLA observations at 2 and 6 cm have been obtained for six hydrogen-deficient stars R CrB, HD 160641, BD — 9°4395, V348 Sgr, MV Sgr and Sgrv Upper limits to the massloss rates have been estimated for some of these using the upper limits to the radio flux density. National Radio Astronomy Observatory’s Very Large Array is operated by Associated Universities Inc. under contract with National Science Foundation, USA  相似文献   

Large-Scale Soil Resource Mapping Using IRS-P6 LISS-IV and Cartosat-1 DEM in Basaltic Terrain of Central India     

Nisha Sahu  S. K. Singh  G. P. Obi Reddy  Nirmal Kumar  M. S. S. Nagaraju  Rajeev Srivastava 《Journal of the Indian Society of Remote Sensing》2016,44(5):811-819

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On the relation of vegetation and southwest monsoon rainfall over Western Ghats,India     

T. V. Lakshmi Kumar  Koteswara Rao  R. Uma  Humberto Barbosa  K. V. K. R. K. Patnaik  Emily Prabha Jothi 《Natural Hazards》2016,80(1):425-444

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Use of remote sensing in characterization and management of Dhamni micro-watershed of Chandrapur district of Maharashtra     

Elvis A. Shukla  Jagdish Prasad  M. S. S. Nagaraju  Rajeev Srivastava  D. L. Kauraw 《Journal of the Indian Society of Remote Sensing》2009,37(1):129-137

Soil resource characterization of Dhamni micro-watershed in Chandrapur district of Maharashtra was carried out using IRS-1D LISS-III data in conjunction with field survey and ancillary data. The study indicates that nearly 84.2 per cent of the total geographical area of the watershed is under cultivation. Forest (mainly degraded) occupy only 4.5 per cent area Whereas wasteland with scrub cover 9.4 per cent area of the watershed. Nine soil series were tentatively identified and mapped as soil series association in to five mapping units. These soils belong to order Inceptisol, Vertisol and Mollisol. Except the soils of wasteland with scrub, other soils are moderately suitable for pigeonpea and soybean and have average to good productivity.  相似文献   

Interferometer phase calibration sources — II. The region 0° ≤ δ_B1950≤ +20°     

Browne  Patnaik  Wilkinson  & Wrobel 《Monthly notices of the Royal Astronomical Society》1998,293(3):257-287

We present a catalogue of 781 compact radio sources in the declination range 0° ≤ δ_B1950≤ +20° whose positions have been measured to an rms accuracy of about 14 mas with the Very Large Array (VLA). These sources are primarily intended for use as phase calibration sources for the Jodrell Bank MERLIN. However, they will also be suitable as phase calibrators for the VLA and can be considered as candidate phase calibrators for very long-baseline interferometry (VLBI) networks.  相似文献   

Tectonic implications of new U–Pb zircon ages of the Ladakh batholith,Indus suture zone,northwest Himalaya,India     

Rajeev Upadhyay  Wolfgang Frisch  Wolfgang Siebel 《地学学报》2008,20(4):309-317

We determined U–Pb ages on zircons from Ladakh granitoid samples of three previously undated plutons and deduced four distinct age groups between c. 67 and c. 45 Ma (66.6 ± 2.1, 57.6 ± 1.4, 53.4 ± 1.8, 52.50 ± 0.53 and 45.27 ± 0.56 Ma). This suggests that the Ladakh batholith grew by addition of at least four distinct subduction‐related magma pulses at c. 67, 58, 53 and 45 Ma, thus indicating that the belt was continuously active throughout the Palaeocene and the Middle Eocene (Lutetian). The 45.27 ± 0.56 Ma pluton at Daah‐Hanu is the last major calcalkaline arc magmatic pulse in the Ladakh batholith. Thereafter, the subduction‐related major plutonism gradually waned. The earlier estimate for the youngest pluton within the Ladakh batholith is 49.8 ± 0.8 Ma for the Leh pluton ( J. Geol., 2000, 108 , 303 ).  相似文献   

Further VLA observations of hydrogen deficient stars     

N. Kameswara Rao  V. R. Venugopal  A. R. Patnaik 《Journal of Astrophysics and Astronomy》1987,8(3):227-230

VLA observations at 6 cm have been obtained for three hydrogen-deficient objects υ Sgr, V 348 Sgr, and A bell 58. A bell 58 was also observed at 2 cm. Only upper limits to the flux density could be set for these sources. A new radio source at 6 cm was found in the field of υ Sgr. The upper limit for 6 cm flux density of V348 Sgr sets an upper limit to its reddening asE(B–V) ≤ 0.65. The hydrogen deficient planetary nebula A 58 shows much lower radio flux than expected from the infrared-radio flux density relationship of planetary nebulae. National Radio Astronomy Observatory’s Very Large Array is operated by Associated Universities Inc. under contract with National Science Foundation, USA.  相似文献   

Diffusion coefficient of neutrinos in a pre-supernova star     

B. Banerjee  S. M. Chitre  Namrata Rajeev 《Astrophysics and Space Science》1993,205(2):343-353

The diffusion coefficient of neutrinos in the trapping regime in a presupernova star,where the scattering of neutrinos by nuclei is the dominant effect, is calculated within the framework of relativistic kinetic theory in the lowest order Chapman-Enskog approximation. The screening of the nuclei by ion-ion and electron-electron correlations is also taken into account.  相似文献   

Manganese ore deposits in Koira-Noamundi province of Iron Ore Group, north Orissa, India: In the light of geochemical signature   总被引：1，自引：0，他引：1  

B.K. Mohapatra  P.P. Mishra  P.P. Singh  Rajeev 《Chemie der Erde / Geochemistry》2009,69(4):377-394

Several small Mn–Fe oxide and Mn-oxide ore bodies associated with Precambrian Iron Ore Group of rocks are located within Koira-Noamundi province of north Orissa, India. These deposits are classified into in situ (stratiform), remobilized (stratabound) and reworked categories based on their field disposition. Volcaniclastic/terrigenous shale in large geographic extension is associated with these ore bodies.The in situ ore bodies are characterised by cryptomelane-, romanechite- and hematite-dominating minerals, low Mn/Fe ratio (1.1) and relatively lower abundance of trace (1500–2500 ppm) constituents. In such type of deposits the stratigraphic conformity of oxides with the tuffaceous shale suggests precipitation of Mn and Fe at a time of decreased volcaniclastic/terrigenous contribution. The minor and trace elements were removed from solution by adsorption rather than by precipitation. Both Mn and Fe oxides when precipitated adsorb trace elements strongly but the partitioning of elements takes place during diagenesis. The inter-elemental relationship reveals that Cu, Co, Ni, Pb and Zn were adsorbed on precipitating hydrous Mn oxides and form manganates. Some of these elements probably get desorbed from Fe oxide because of their inability to substitute for Fe³⁺ in the lattice of its oxide. However, P, V, As and Mo were less partitioned and retained in Fe-oxide phase. Positive correlation between Al₂O₃ and SiO₂, MgO, Na₂O, TiO₂ and some traces like Li, Nb, Sc, Y, Zr, Th and U points to their contribution through volcaniclastic/terrigenous detritus of both mafic and acidic composition.The remobilized ore bodies are developed in a later stage through dissolution, remobilization and reprecipitation of Mn oxides in favorable structural weak planes under supergene environment. Increase in average Mn/Fe ratio (8) and trace content (5000–8500 ppm) by 5–2.5 orders of magnitude, respectively, or more above its abundance in adjoining/underlying protore is characteristic of these deposits. The newly formed Mn ores constituting lithiophorite, cryptomelane/romanechite and goethite get quantitatively enriched in traces like Cu, Co, Ni, Pb and Zn. Positive correlation between Mn, Li, Co and Zn is due to the formation of mineral of lithiophorite–chalcophanite group during redistribution and reconcentration of Mn oxide. P and V, which were present in Fe oxide, also get dissolved and reprecipitate with Fe oxyhydroxide in these ores. Some other elements like Y, Th and U show positive relation with Fe. This is probably due to leaching of these elements during chemical weathering of associated shale and getting re-adsorbed in Fe-oxyhydroxide phase.However, under oxidizing environment selective cations like Ba, K, etc. resorb from Mn-structure, resulting in the development of pyrolusite (Mn/Fe>20). In such transformation, trace metals from pyrolusitic structure expels out, resulting thereby in a considerable reduction in total trace value (<3000 ppm).The reworked ore bodies are allochthonous in nature and developed through a number of stages during terrain evolution and lateritisation. Secondary processes such as reworking of pre-existing crust; solution and remobilization; precipitation and cementation and transport, etc. are responsible for their development. Such deposits are usually very low in Mn/Fe ratio (3) and trace content (<2000 ppm).  相似文献   

A Closed Loop Wastewater Biorefinery Based on the Recently Introduced SHEFROL Reactor and Two Freely Available Macrophytes     

Tabassum-Abbasi  Pratiksha Patnaik  Shahid Abbas Abbasi 《洁净——土壤、空气、水》2023,51(3):2100287

With an objective to develop a closed loop wastewater biorefinery, the performance of two free floating aquatic weeds water hyacinth (Eichhornia crassipes, Mart, Solms) and salvinia (Salvinia molesta, Mitchell) is explored when either is used as the main bioagent for treating sewage in “sheet flow root level” (SHEFROL) bioreactors. Both the macrophytes prove to be easy to propagate and maintain while they are able to help in achieving significant primary, secondary, and tertiary treatment steps of greywater in a single step. Water hyacinth is able to remove suspended solids, chemical oxygen demand (COD), biological oxygen demand (BOD), total Kjeldahl nitrogen, soluble phosphorous, zinc, copper, nickel, and manganese to the average extents of 81%, 79%, 43%, 41%, 40%, 36%, 34%, and 29%, respectively. The reduction in COD and BOD levels achieved by salvinia is marginally lesser than by water hyacinth but in terms of the removal of other pollutants, the performance of salvinia is comparable to that of water hyacinth. It is possible to convert the dead or harvested plants to organic fertilizer thus making it a closed-loop system with no waste of its own.  相似文献