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571.
S. K. Srivastava K. K. Parashar K. Ramesh Kumar S. Nayak A. Latha 《Journal of the Geological Society of India》2017,89(4):386-390
A composite dike has been noticed in basement granite in the vicinity of Srisailam sub-basin near village Akkawaram, Mahabubnagar district, Telangana. It is trending N-S and traced over an extent of 600m in eastern flank of Akkavaram outlier and comprises rocks of mafic and felsic composition characterized by both gradational and abrupt contacts. On the basis of petrographic studies, felsic part of dike is designated as bostonite and mafic as dolerite. Geochemically, they are grouped into (i) trachyte to trachydacite and (ii) basalt categories. Such dissimilar mineralogical and chemical characters in a single dike may be due to coexistence of magma of contrasting composition and provides vital information for understanding the two phase liquid. Interestingly, high uranium values (0.022% U3O8) recorded in parts of felsic portion. 相似文献
572.
J. P. Shrivastava Mansoor Ahmad Surabhi Srivastava 《Journal of the Geological Society of India》2012,80(2):177-188
Clay minerals associated with intra-volcanic bole horizons of varied colours and thicknesses contain montmorillonite, halloysite and kaolinite, show distinct microstructures and microaggregates. In kaolinite, Fe3+ ions substitute for Al3+ at octahedral sites. Most of these clays are dioctahedral type, show balance between net layer and interlayer charges. The interstratified illite — smectite (I/S) mixed layers containing variable proportions of montmorillonite. Illite contains sheet-like, well oriented microaggregates. The parallel stacks of chlorite sheets show chlorite/smectite (C/S) mixed layers. Progressive enrichment of Fe and depletion of Al ions with the advancement of kaolinization process is observed. High order of structural and compositional maturity observed in these bole clays, indicate long hiatus between the two volcanic episodes. 相似文献
573.
Chia-Chuan Liu Jyoti Prakash Maity Jiin-Shuh Jean A. H. M. Selim Reza Zhaohui Li Bibhash Nath Ming-Kuo Lee Kao-Hung Lin Prosun Bhattacharya 《Environmental Earth Sciences》2012,66(5):1513-1523
Fluid and mud samples were collected from Wushanting (WST), Hsiaokunshui (HKS), Yenshuikeng (YSK), Kuantzeling (KZL), and
Kunshuiping (KSP) mud volcanoes of southwestern Taiwan. Concentrations of major ions and trace elements in mud volcanic fluids
were analyzed to find the possible linkage to elevated arsenic (As) concentrations in the Chianan plain groundwater. The elevated
Na+, K+, and Cl− concentrations indicated possible marine origin of the fluids. The trace element concentrations in the mud volcanic fluids
were generally low, but the As concentrations were up to 0.12 mg/L. High contents of As, Fe, and Mn were observed in the mud
samples. Saturation index calculations indicated that both carbonate and oxide minerals acted as potential sinks for As in
the mud volcanic fluids. Arsenic in the dewatering fluids and muds may be transported by the subsurface flow and surface streams
as suspended solids and eventually deposited in the Chianan plain aquifers. Under reducing conditions, As may be released
from the host minerals (such as Fe- and Mn-oxides/hydroxides), thereby causing widespread groundwater As pollution. 相似文献
574.
To prevent infection with Dracunculus medinensis, a carrier host, the copepod Cyclops, has to be controlled. After preceding laboratory investigations a field trial with well water and different additions of chlorine and sodium permanganate is carried out. The exposure is performed at an ambient temperature of 25… 40 °C and in bright and dark samples (5… 11 h of sunshine/d) as well as in the well. The residual concentrations of the two chemicals are an exponential function of the time of exposure with half-times between 6 and 23 h for chlorine and 11… 30 h for sodium permanganate. The depletion of the two oxidizing agents under light is faster than in darkness. Dosage should be done in such a way that the LC90,24h after 24 h of exposure will not be fallen below; in a specific case, this guarantees at the same time that the permissible concentrations for drinking water will not be reached 96 h after addition. For this, initial concentrations of 30 mg 1 Cl2 or 50 mg/l KMnOr are necessary. Under these conditions, the Cyclops population had died on the seventh day after the application of chemicals, but after seven weeks it reached the original density again. With one application of chloride or sodium permanganate a week Dracunculiasis can be completely controlled. 相似文献
575.
A non-iterative analytical scheme is developed for unstable stratification that parametrizes the Monin–Obukhov stability parameter \(\zeta \) (\({=}z{/}L\), where z is the height above the ground and L is the Obukhov length) in terms of bulk Richardson number (\(Ri_B\)) within the framework of Businger–Dyer type similarity functions. The proposed scheme is valid for a wide range of roughness lengths of heat and momentum. The absolute relative error in the transfer coefficients of heat and momentum is found to be less than 1.5% as compared to those obtained from an iterative scheme for Businger–Dyer type similarity functions. An attempt has been made to extend this scheme to incorporate the similarity functions having a theoretically consistent free convection limit. Further, the performance of the scheme is evaluated using observational data from two different sites. The proposed scheme is simple, non-iterative and relatively more accurate compared to the schemes reported in the literature and can be used as a potential alternative to iterative schemes used in numerical models of the atmosphere. 相似文献
576.
Deepak C. Srivastava 《Journal of Earth System Science》1990,99(2):215-228
A multiple-deformation sequence is established for different types of gneisses, mafic-paleosomes and banded magnetite quartzites
(BMQ) exposed within the area. In gneisses, the basin-shaped map pattern represents the type-i interference structure formed
due to the overprinting of F3 folds with ENE striking axial planes on F2 folds with axial planes striking NNW. The BMQ band occurring as an enclave within the gneissic country, represents a large
scale F1 fold with relatively smaller scale F2 folds developed on its limbs. Mafic-paleosomes within the streaky-charnockitic-gneisses exhibit structures formed due to
the interference of more than two phases of folding (F1,Fla,F2,F3). It is shown that the deformation plan in these rocks is consistent with the generalized deformation scheme for Granite-greenstone
belts. The difference in the map pattern of Granite-greenstone belts and Granulite-charnockite terrains is ascribed to the
variance in Theological properties, layerthickness ratios and local displacement directions during different phases of folding.
These differences apart, both the Granite-greenstone and Granulite-charnockite provinces in South India are deformed by an
early isoclinal folding which is successively overprinted by folding on NNW and ENE striking axial planes. 相似文献
577.
In the first part of the paper the Newtonian analogue of force for theC-metric has been investigated. To the first-order of approximation in the absence of acceleration of the particle generating theC-metric, one component of the force vector corresponds to the Newtonian analogue of force. In general there are relativistic correction terms due to acceleration term in theC-metric. In the second part of the paper the motion of a freely falling body has been investigated. It is found that plane orbits are not possible. Also the radial fall is not possible and in the equation of the orbit there are terms having no classical analogue. They can be interpreted as the effect of the dragging of the inertial frame produced by the rectilinear acceleration. 相似文献
578.
In Nepal, nearly half of the total land is covered by forest, which holds a potentially important position in promoting rural livelihoods and in alleviating rural poverty. The rural landscape that encompasses an agrarian economy, a fragile ecology, and a complex and differentiated society is changing rapidly in Nepal today. Although poverty alleviation has been one of the top priorities for national development since 1976, poverty still remains widespread, persistent and it is also an acute problem in Nepal, where people are in a state of deprivation with regard to incomes, clothing, housing, healthcare, education, sanitary facilities and human rights. Thus, Nepal is considered as one of the poorest countries in South-Asia, with 25.2% people living below the poverty line. The objective of this study was to assess changes in poverty of forest users brought on by the community forestry program, in order to analyze the level of participation in community forestry management activities. For this study, Bajhang district was chosen as the study site, which is one of the poorest and most remote districts in the country of Nepal. Different Participatory Rural Appraisal methods such as face-to face interviews, focus group discussions and key informants’ interviews including secondary data were used to gather information. The findings showed that the forest users’ participation in meetings, discussion and other activities, like community forestry management or silvicultural operation related to community forestry, was high. The assessment found that 42.3%, 32.6% and 25.1% of respondents strongly agreed, agreed and were neutral, respectively, towards the idea that poverty reduction from community forests had occurred. The results showed almost all the respondents were depended upon agriculture and/or forest resources for their livelihoods. Different ecosystem services such as ethnomedicines, aesthetic value and ecotourism, control of soil erosion/land-slides, water recharge and soil fertility have increased due to the decomposition of leaf litter. This was apparent from the formulation of community forests. Poverty in rural areas of the country is still higher than in urban areas and the incidence of poverty is the highest in the Far western Province where this research was conducted, Therefore, the government, policy makers and other stakeholders should work hand-in-hand to effectively reduce the poverty that persists in Nepal. 相似文献
579.
Ankur Srivastava Patricia M. Saco Jose F. Rodriguez Nikul Kumari Kwok Pan Chun Omer Yetemen 《水文研究》2021,35(1):e13990
Previous studies on semi-arid ecosystems have shown high values of soil moisture variability (SMV) primarily induced by the combined effects of non-uniform precipitation, incoming solar radiation, and soil and vegetation properties. However, the relative impact of these various factors on SMV has been difficult to evaluate due to limited availability of field data. In addition, only a limited number of studies have analysed the role of landscape morphology on SMV. Here we use numerical simulations of a simple hydrological model, the Bucket Grassland Model, to systematically analyse the effect of each contributing factor on SMV on two different landscape morphologies. The two different landform morphologies represent landscapes dominated respectively by either diffusive erosion or fluvial erosion processes. We conducted various simulations driven by a stochastically generated 100-year climate time series, which is long enough to capture climatic fluctuations, in order to understand the effect of various soil moisture controlling factors on the spatiotemporal SMV. Our modelling results show that the fluvial dominated landscapes promote higher spatial SMV than the diffusive dominated ones. Further, the role of landform morphology on SMV is more pronounced in regions where the spatial variability of incoming solar radiation and precipitation is high. 相似文献
580.
D. C. Srivastava † S. K. Sahay 《Monthly notices of the Royal Astronomical Society》2002,337(1):305-314
We present the Fourier Transform of a continuous gravitational wave. We have analysed the data set for a 1-d observation time and our analysis is applicable for an arbitrary location of detector and source. We have taken into account the effects arising due to the rotational as well as orbital motions of the Earth. 相似文献