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1.
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
2.
Namrata Das Saroj Sundar Baral Parth Sarathi Mahapatra Trupti Das Gautam Roy Chaudhury Surendra Nath Das 《Theoretical and Applied Climatology》2012,110(1-2):55-63
Precipitation samples collected during 2005–2009 from a rural forest station of Bhubaneswar were analyzed for their chemical composition. The samples were collected through a wet-only (WO) collector and two bulk (B1 and B2) collectors. The ions were evenly balanced indicating good data quality. The overall pH of rainwater was slightly acidic and ~47% of all rain events during the period were acidic (pH?<?5.6). Multilinear regression analysis showed relation between the free acidity (H+) and other components in rainwater. Enrichment factors (EF) of the major components with respect to their sources such as marine and crustal were calculated. Maximum EF was observed for NO 3 ? for both marine and crustal sources for all the three collectors. Source apportionments were also carried for the ions. Trend analysis showed continuous increase in most of the ions over years during the study period driven by anthropogenic emissions. Statistical/factorial analysis established correlation among different ions. 相似文献
3.
Ana Carolina Sarmento Buarque Namrata Bhattacharya-Mis Maria Clara Fava Felipe Augusto Arguello de Souza Eduardo Mario Mendiondo 《水文科学杂志》2020,65(7):1075-1083
ABSTRACTThe city of São Carlos, state of São Paulo, Brazil, has a historical coexistence between society and floods. Unplanned urbanization in this area is a representative feature of how Brazilian cities have developed, undermining the impact of natural hazards. The Gregório Creek catchment is an enigma of complex dynamics concerning the relationship between humans and water in Brazilian cities. Our hypothesis is that social memory of floods can improve future resilience. In this paper we analyse flood risk dynamics in a small urban catchment, identify the impacts of social memory on building resilience and propose measures to reduce the risk of floods. We applied a socio-hydrological model using data collected from newspapers from 1940 to 2018. The model was able to elucidate human–water processes in the catchment and the historical source data proved to be a useful tool to fill gaps in the data in small urban basins. 相似文献
4.
Parth S. Mahapatra Sipra Panda Namrata Das Satyajit Rath Trupti Das 《Theoretical and Applied Climatology》2014,117(1-2):133-147
Black carbon (BC) mass concentration variation has been studied, over a period of 2 years (June 2010–May 2012) at Bhubaneswar. Daily, monthly and seasonal measurements revealed a clear winter maxima (5.6 μg/m3) of BC followed by post-monsoon (4.05 μg/m3), monsoon (3.02 μg/m3) and pre-monsoon (2.46 μg/m3). Nighttime BC mass concentrations have been found to be distinctly higher during winter followed by post-monsoon and monsoon. Investigations reveal that the winter maxima are due to a stable atmospheric condition and long-range transport over the Indo-Gangetic Plain and Western Asia. Local boundary layer dynamics and anthropogenic activities have been assumed to have a pronounced effect on the diurnal cycle seasonally. Statistical analysis suggests significant variation of BC during the months and non-significant during the days. The study also gives an insight into importance of BC study from health angle and suggests an assessment and management framework. Source apportionment study suggests that BC mass concentration observed at Bhubaneswar is generally dominated by fossil fuel combustion. 相似文献
5.
Shibendu Shankar Ray Namrata Jain R. K. Arora S. Chavan Sushma Panigrahy 《Journal of the Indian Society of Remote Sensing》2011,39(2):161-169
The study was carried out to investigate the utility of hyperspectral reflectance data for potato late blight disease detection.
The hyperspectral data was collected for potato crop at different level of disease infestation using hand-held spectroradiometer
over the spectral range of 325–1075 nm. The data was averaged into 10-nm wide wavebands, resulting in 75 narrowbands. The
reflectance curve was partitioned into five regions, viz. 400–500 nm, 520–590 nm, 620–680 nm, 770–860 nm and 920–1050 nm.
The notable differences in healthy and diseased potato plants were noticed in 770–860 nm and 920–1050 nm range. Vegetation
indices, namely NDVI, SR, SAVI and red edge were calculated using reflectance values. The differences between the vegetation
indices for plants at different levels of disease infestation were found highly significant. The optimal hyperspectral wavebands
to discriminate the healthy plants from disease infested plants were 540, 610, 620, 700, 710, 730, 780 and 1040 nm whereas
upto 25% infestation could be discriminated using reflectance at 710, 720 and 750 nm. 相似文献
6.
We investigate the process of photon capture by strong magnetic fields, by transforming it into a positronium, and the subsequent decay of the positronium into two photons. We discuss the implications of this process for the polar gap models of pulsars. We find that the capture process is energy-dependent and photons above a certain energy (depending on the magnetic field) are not captured and can decay into electron-positron pairs. This leads to increased gap heights in the modle and leads to higher luminosities than found earlier. We also find that it may be possible for very high-energy positronia to escape the magnetosphere of the pulsar and be observed near the Earth as photons in agreement with the recent observations of 1012 eV gamma-rays from some pulsars. 相似文献
7.
8.
Kireet Kumar M. S. Miral Sneh Joshi Namrata Pant Varun Joshi L. M. Joshi 《Environmental Geology》2009,58(6):1151-1159
The present study investigates solute dynamics of meltwater of Gangotri glacier system in terms of association of different
chemical compounds with the geology of the area. In the meltwater, the presence of cations varied as c(Mg2+) > c(Ca2+) > c(Na+) > c(K+), while order of concentration of anions has been c(HCO3
−) > c(SO4
2−) > c(Cl−) > c(NO3
−) in years 2003 and 2004. The magnesium and calcium are found as the dominant cations along with bicarbonate and sulphate
as dominant anions. The high ratios of c(Ca2+ + Mg2+)/total cations and c(Ca2+ + Mg2+)/c(Na+ + K+) indicate that the meltwater chemistry of the Gangotri glacier system catchment is mostly controlled by carbonate weathering.
Attempts are made to develop rating curves for discharge and different cations. Sporadic rise in discharge without corresponding
rise in concentration of most of cations is responsible for their loose correlation in a compound valley glacier like Gangotri
glacier. 相似文献
9.
Parth Sarathi Mahapatra Sanak Ray Namrata Das Ayusman Mohanty T. S. Ramulu Trupti Das G. Roy Chaudhury S. N. Das 《Theoretical and Applied Climatology》2013,112(1-2):243-251
Acid- and water-soluble component of suspended particulate matter was studied from January 2009 to December 2009 at Bhubaneshwar, an urban coastal location of eastern India, by high-volume sampler, environmental dust monitor using GRIMM®, and scanning electron microscope and energy dispersive X-ray spectrometer. The water-soluble components accounted for 30–45 % of the total suspended particulate matter, and the major elements were observed to be ammonium and nitrate as the cationic and anionic species, respectively. The acid-soluble component like copper, nickel, cobalt, iron, and lead accounted for 5–15 % of the total particulate matter concentration. The composition of particulate matter shows a clear seasonal variation in relation to wind speed, wind direction, and trajectories of the air mass movement. The GRIMM spectrometer analysis shows higher concentration of fine particulate matter. Source apportionment and enrichment factor analysis indicated that except sodium and chloride, all other elements have emerged from different sources such as crustal as well as anthropogenic. 相似文献
10.
We have investigated the formation of polar gaps in pulsars as envisaged by Ruderman and Sutherland (1975) in the presence of photon conversion into positronia (Shabad and Usov, 1985; Heroldet al., 1985) and dissociation of positronia by strong electric fields. For the emission of curvature radiation near the pulsar's surface, we have used formulae which are valid in the extreme relativistic regime. We find that the gap formation is not affected, only the gap height is generally slightly increased. In the sample of pulsars that we have studied, in most cases there is likely to be enough plasma in the gap to initiate processes producing radio emission in accordance with the theory. In some cases we found the possibility of emission of high-energy photons outside the pulsar magnetosphere, as was suggested earlier by us (Bhatiaet al., 1987) in conformity with some of the observations. 相似文献