Toxicity of Nickel to a Fresh Water Teleost,Colisa fasciatus     

N. Kumar  K. Nath 《洁净——土壤、空气、水》1987,15(3):313-315

The acute toxicity of nickel sulphate to Colisa fasciatus has been evaluated by static bioassay experiments. The LC 50 values of nickel for 24, 48, 72 and 96 h were computed to be 96.12, 60.18, 24.45 and 16.72 mg/1, respectively. Their 95 % confidence limits have also been investigated.  相似文献   

Toxic Impact of Hexavalent Chromium on the BLOOD Pyruvate of Colisa fasciatus     

Dr. K. Nath  N. Kumar 《洁净——土壤、空气、水》1987,15(5):531-534

The blood pyruvate levels of a freshwater tropical teleost Colisa fasciatus were investigated from 3 to 96 h following sublethal intoxication of 48 ppm hexavalent chromium. The blood pyruvate levels rose at every time period studied from 3… 96 h. A statistically significant elevation is observed from 24 h and progresses up to 96 h. The maximum elevation of 92.86% has been recorded at 72 h (p<0.001).  相似文献   

Land use indicators of a watershed in arid region, western Rajasthan using Remote Sensing and GIS     

Debashis Chakraborty  Dibyendu Dutta  H Chandrasekharan 《Journal of the Indian Society of Remote Sensing》2001,29(3):115-128

The vegetation dynamics and land use/land cover types of Birantiya Kalan watershed located in the arid tracts of western Rajasthan have been characterized and evaluated using Remote Sensing and Geographical Information System (GIS). The watershed under study falls in the transitional plain of Luni Basin and is characterized by Aravali ranges in the eastern half and vast alluvial plains in the west. The land use/land cover types, as identified are cropland, fallow, forest, land with scrub, land without scrub, sandy area and the water body. Land with scrub occupied maximum area (39% area of the watershed) in 1996 in place of crop land which was dominant (43% of total area) in the year 1988. During eight years period, seasonal fallow land increased significantly and the areal extent of water body decreased to almost half. Vegetation vigour types have been classified into very poor, poor. moderate, good and very good categories. Moderate vigour type reduced from 62 to 27% and poor type increased from 34 to 68% during the period 1988 to 1996. Other vegetation vigour types have not shown any significant changes. To quantify the changes over the years in both vegetation and land use/land cover, weightages have been given to each type and composite values of both vegetation vigour and land use types for 1996 and 1988 have been calculated. It has been observed that the ratio for vegetation vigour has been found to be 0.85 showing that the overall vegetation have not improved after the treatment. The ratio for land use is found to be 1.01, which indicates negligible change in land use.  相似文献   

Influence of forest fire episodes on the distribution of gaseous air pollutants over Uttarakhand,India     

Yesobu Yarragunta  Debashis Mitra  Harish Chandra Chandola 《地理信息系统科学与遥感》2020,57(2):190-206

ABSTRACT

Widespread forest fire events occurred in the foothills of North Western Himalaya during 24 April to 2 May 2016 (Event-1) and 20–30 May 2018 (Event-2). Their impacts were investigated on the distribution of pollutant gases ozone (O₃), carbon monoxide (CO), and oxides of nitrogen (NOx) over Uttarakhand using simulations of Weather Research and Forecasting model coupled with chemistry (WRF-Chem) and in-situ observations of these gases over Dehradun, the capital of Uttarakhand. During Event-1, the observed CO mixing ratio over Dehradun increased from 25 April 2016 onwards, attained maximum (705.8 ± 258 ppbv) on 2 May 2016 and subsequently decreased. The rate of increase of daily baseline CO was 29 ppbv/day during HFAP (High Fire Activity Period). During Event-2, daily average concentrations of CO, O₃, and NOx showed systematic increase over Dehradun during HFAP period. The rate of increase of CO was 9 ppbv/day, while it was very small for NOx and O₃. To quantitatively estimate the influence of forest fire emissions, two WRF-Chem simulations were made: one with biomass burning (BB) emissions and other without BB emissions. These simulations showed 52% (34%) enhancement in CO, 52% (32%) enhancement in NOx, and 11% (9%) enhancement in O₃ during HFAP for Event-1 (Event-2). A clear positive correlation (r = 0.89 for Event-1, r = 0.69 for Event-2) was found between ?O₃ (O_{3with BB} minus O_{3without BB}) and ?CO (CO_{with BB} minus CO_{without BB}), indicating rapid production of ozone in the fire plumes. For both the events, the vertical distribution of ?O₃, ?CO, and ?NOx showed that forest fire emissions influenced the air quality upto 6.5 km altitude. Peaks in ?O₃, ?CO, and ?NOx during different days suggested the role of varying dispersion and horizontal mixing of fire plumes.  相似文献   

Spherical mhd shock waves under the action of monochromatic radiation     

Onkar Nath  H. S. Takhar 《Astrophysics and Space Science》1993,202(2):355-362

Self-similar MHD shock waves have been studied under the action of monochromatic radiation into a non-uniform stellar atmosphere with a constant intensity on unit area. It has been assumed that the radiation flux moves through the gas. Variation of flow variables have heen shown in tables for two different cases.  相似文献   

Exact solution of a problem in a stellar atmosphere using the Laplace transform and the Wiener-Hopf technique     

Rabindra Nath Das 《Astrophysics and Space Science》1979,63(1):155-170

The general equation for radiative transfer of line scattering intensity — including the effects of scattering, absorption and thermal emission — in the Milne-Eddington model is considered here. The scattering function is assumed to be quadratically anisotropic in the cosine of the scattering angle, and Planck's intensity function is assumed for thermal emission. The exact solutions for emergent intensity from the bounding face and the intensity at any optical depth are obtained by the method of the Laplace transform in combination with the Wiener-Hopf technique.  相似文献   

A mapping finite element method for stress calculation in two-dimensions     

B. Nath 《国际地质力学数值与分析法杂志》1982,6(1):141-145

A mapping finite element method is proposed for the solution of elastic problems in two-dimensions. This method, based on the logarithmic condensation of physical space, is found to give significantly greater accuracy than when the problem is solved in the physical plane using the standard FEM. Logarithmic condensation of space also permits the solution of large aspect-ratio problems of this type, accurately and economically.  相似文献   

Nier Prize Citation for Gopalan Srinivasan     

Jitendra Nath Goswami 《Meteoritics & planetary science》1998,33(Z4):A4-A4

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Propagation of cylindrical shock waves under the action of monochromatic radiation     

Onkar Nath  H. S. Takhar 《Astrophysics and Space Science》1990,166(1):35-39

A model of cylindrical shock waves is investigated under the action of monochromatic radiation into non-uniform stellar interiors with a constant intensity on a unit area. We have assumed that the radiation flux moves through the gas.  相似文献   

From Nearby Low Luminosity AGN to High Redshift Radio Galaxies: Science Interests with Square Kilometre Array     

P. Kharb  D. V. Lal  V. Singh  J. Bagchi  C. H. Ishwara Chandra  A. Hota  C. Konar  Y. Wadadekar  P. Shastri  M. Das  K. Baliyan  B. B. Nath  M. Pandey-Pommier 《Journal of Astrophysics and Astronomy》2016,37(4):34

We present detailed science cases that a large fraction of the Indian AGN community is interested in pursuing with the upcoming Square Kilometre Array (SKA). These interests range from understanding low luminosity active galactic nuclei in the nearby Universe to powerful radio galaxies at high redshifts. Important unresolved science questions in AGN physics are discussed. Ongoing low-frequency surveys with the SKA pathfinder telescope GMRT, are highlighted.  相似文献