The Influence of a Teleost Clarias batrachus (L.) on the Behaviour of Different Species of Nitrogen in Water     

B. B. Jana  S. Sengupta  M. Sinha 《洁净——土壤、空气、水》1986,14(4):375-384

Different experimental conditions (fed large, fed small, starved large, starved small groups, batch offered ration during experiment and low fish loading for a constant volume of water) of the carnivorous fish Clarias batrachus resulted in marked changes in the concentration of different N species (ammonium-N, nitrate-N, nitrate-N, organic-N as well as the sum of all forms of N) in aquaria water. Organic forms of nitrogen were the most important species of nitrogen excreted by the test fish. The maintenance nitrogen excretion rate was distinctly higher in larger fishes than in smaller ones. Different species of N were found to differ significantly depending upon the fed or starved conditions as well as small or large groups. A reduced level of oxygen in experimental aquaria inhibited the synthesis of nitrate which was maximum in control aquaria with considerably higher values of oxygen.  相似文献   

Biomass Determination in Some Species Using a Geometric Equivalent Technique of Plankton Organisms     

S. Sarkar  B. B. Jana 《洁净——土壤、空气、水》1985,13(2):217-221

The plankton collected from three fish ponds shows a considerable variability within a pond, between the ponds and in the course of the year. The individual volumes or weights are (minimum—mean—maximum): Gleotrichia echinulata 41–252–879 μg³, Chlorella vulgaris 18–42–94 μm³, Oscillatoria amphigranulata 99–306–827 μm³, Brachionus plicatilis 1–4.918 μg, nauplia 0.5–1.25–2.35 μg, Mesocyclops hyalinus 4–45–369—μg, Heliodiaptomus viduus 41–202–288 μg, Daphnia carinata 186–1468–4578 μg.  相似文献   

Numerical modelling of time-harmonic seismic wave fields in simple structures by the gaussian beam method. part I     

Jana Konopásková  Vlastislav Červený  Reviewer I. Pšenčík 《Studia Geophysica et Geodaetica》1984,28(1):19-35

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The Influence of the Fish Clarias batrachus on the Physicochemical Properties of Water under Laboratory Conditions     

B. B. Jana  M. Sinha  S. Gupta 《洁净——土壤、空气、水》1984,12(1):107-113

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Ab initio calculations on (OH)4 defects in α-quartz     

J. S. Lin  M. C. Payne  V. Heine  J. D. C. McConnell 《Physics and Chemistry of Minerals》1994,21(3):150-155

Ab initio total energy calculations based on a new optimized oxygen psuedopotential have been used to study the structures and relative energies of α-quartz, a partly (OH)₄ substituted version of the α-quartz structure, and interstitial water molecules in α-quartz. Hydrogen bonds formed from two hydroxyl groups of the (OH)₄ defects in the substituted α-quartz structure promote a stable structure for the defect α-quartz at low temperature. Comparable ab initio calculation of the energy of the interstitial water molecule in the quartz structure indicates that, energetically, the (OH)₄ defect is likely to be strongly favoured as a mode for the incorporation of water. Ab initio stress calculations confirm that the (OH)₄ defect in quartz has a large associated stress field which is likely to lead to segregation of these defects on supersaturation in wet quartz. The calculations indicate that segregation should occur in the plane (10 0) of the α-quartz structure.  相似文献   

Application of remote sensing in the study of geomorphic processes and lanforms in piedmont zone of Darjeeling Sub-Himalaya     

M M Jana 《Journal of the Indian Society of Remote Sensing》2002,30(1-2):61-72

The piedmont zone, located between the foothills of Darjeeling Sub-Himalaya and the flat plains of North Bengal is elongated from west to east and its average height varies from 150 m in the north to 50 m in the south. Morphologically, the region is divided into three distinct physiographic units. Many large and small rivers originated from the Darjeeling Sub-Himalayas intersect it. Most of these rivers have their large catchment area in the mountainous tract. The study area has about 350 cm of annual rainfall and peak discharge in the rivers is very high during monsoon period. Rivers carry large amount of sediments, gravels, and pebbles both in suspension and traction and these materials are deposited in the foothills of the Sub-Himalaya as fan deposits and on the riverbeds making braided channels. Landforms in the study area are mainly complex and their origins are influenced by neotectonic and fluvial activities. Many rivers terraces, palaeo-channels, out wash plains, valley-fills and channel bars are formed in the region due to both erosion and depositional processes. These processes and modifications of landforms are still going on in the region.  相似文献   

Numerical Modelling of Time-Harmonic Seismic Wave Fields in Simple Structures by the Gaussian Beam Method. Part I.     

Konop&#;skov&#;  Jana  &#;erven&#;  Vlastislav 《Studia Geophysica et Geodaetica》2002,46(1):67-83

Gaussian beam summation method is used for numerical modelling of seismic wave fields in several simple types of models of media. Main attention is paid to the waves reflected from a plane interface, namely from the vicinity of a critical point. Comparison with exact solutions shows that the Gaussian beam summation method yields sufficiently accurate results even in the singular region of the critical point. By summation of Gaussian beams of waves reflected in the overcritical region even head waves are obtained. In the second part of this work, we shall investigate sensitivity of the results to various parameters, for example, to the initial width of a Gaussian beam, to the parameters of the summation of Gaussian beams, etc.  相似文献   

An ATCA radio-continuum study of the Small Magellanic Cloud – III. Supernova remnants and their environments     

M. D. Filipovi&#;  J. L. Payne  W. Reid  C. W. Danforth  L. Staveley-Smith  P. A. Jones  G. L. White 《Monthly notices of the Royal Astronomical Society》2005,364(1):217-236

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Using operational data to estimate the reliable yields of water-supply wells     

Bruce D.R. Misstear  Sarah Beeson 《Hydrogeology Journal》2000,8(2):177-187

The reliable yield of a water-supply well depends on many different factors, including the properties of the well and the aquifer; the capacities of the pumps, raw-water mains, and treatment works; the interference effects from other wells; and the constraints imposed by abstraction licences, water quality, and environmental issues. A relatively simple methodology for estimating reliable yields has been developed that takes into account all of these factors. The methodology is based mainly on an analysis of water-level and source-output data, where such data are available. Good operational data are especially important when dealing with wells in shallow, unconfined, fissure-flow aquifers, where actual well performance may vary considerably from that predicted using a more analytical approach. Key issues in the yield-assessment process are the identification of a deepest advisable pumping water level, and the collection of the appropriate well, aquifer, and operational data. Although developed for water-supply operators in the United Kingdom, this approach to estimating the reliable yields of water-supply wells using operational data should be applicable to a wide range of hydrogeological conditions elsewhere. Received, September 1998/Revised, May 1999, September 1999/Accepted, October 1999  相似文献   

Photometry of Magellanic Cloud clusters with the Advanced Camera for Surveys – II. The unique LMC cluster ESO 121−SC03     

A. D. Mackey  M. J. Payne  G. F. Gilmore 《Monthly notices of the Royal Astronomical Society》2006,369(2):921-932

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