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Search Results: 1 - 10 of 2710 matches for " Arun Bhakta Shrestha "
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Snow Cover and Glacier Change Study in Nepalese Himalaya Using Remote Sensing and Geographic Information System
Arun Bhakta Shrestha,Sharad Prasad Joshi
Journal of Hydrology and Meteorology , 2009, DOI: 10.3126/jhm.v6i1.5481
Abstract: Snow cover and glaciers in the Himalaya play a major role in the generation of stream flow in south Asia. Various studies have suggested that the glaciers in the Himalaya are in general condition of retreat. The snowline is also found to be retreating. While there are relatively more studies on glaciers fluctuation in the Himalaya, studies on snow cover is relatively sparse.
Projection of Future Climate over the Koshi River Basin Based on CMIP5 GCMs  [PDF]
Rupak Rajbhandari, Arun Bhakta Shrestha, Santosh Nepal, Shahriar Wahid
Atmospheric and Climate Sciences (ACS) , 2016, DOI: 10.4236/acs.2016.62017
Abstract: This paper analyses the climate projections over the Koshi river basin obtained by applying the delta method to eight CMIP5 GCMs for the RCP4.5 and RCP8.5 scenarios. The GCMs were selected to cover the full envelope of possible future ranges from dry and cold to wet and warm projections. The selected coarse resolution GCM outputs were statistically downscaled to the resolution of the historical climate datasets. The scenarios were developed based on the anomaly between the present reference period (1961-1990) and the future period (2021-2050) to generate transient climate change scenarios for the eight GCMs. The analyses were carried out for the whole basin and three physiographic zones: the trans-Himalaya, high-Himalaya and middle mountains, and southern plains. Future projections show a 14% increase in rainfall during the summer monsoon season by 2050. The increase in rainfall is higher over the mountains than the plains. The meagre amount of rainfall in the winter season is projected to further decrease over both the mountain and southern plains areas of the basin for both RCPs. The basin is likely to experience warming throughout the year, although the increase in winter is likely to be higher. The highest increase in temperature is projected to be over the high Himalayan and middle mountain area, with lower increases over the trans-Himalayan and southern plains areas.
Projection of Future Precipitation and Temperature Change over the Transboundary Koshi River Basin Using Regional Climate Model PRECIS  [PDF]
Rupak Rajbhandari, Arun Bhakta Shrestha, Santosh Nepal, Shahriar Wahid
Atmospheric and Climate Sciences (ACS) , 2018, DOI: 10.4236/acs.2018.82012
Abstract: The Koshi river basin sustains the livelihoods of millions of people in the upstream and downstream areas of the basin. People rely on monsoon rainfall for agricultural production, hydropower generation and other livelihood activities. Climate change is expected to have serious implication on its environment. To reduce the adverse impacts of disasters and to better understand the implication of climate change for the sustainable development, initiative in this regard is necessary. Analysis of past meteorological trends and future climate projections can give us a sense of what to expect and how to prepare ourselves and manage available resources. In this paper, we have used a high-resolution climate model, viz., Providing REgional Climates for Impacts Studies (PRECIS), to project future climate scenario over the Koshi river basin for impact assessment. Three outputs of the Quantifying Uncertainties in Model Prediction (QUMP) simulations have been used to project the future climate. These simulations were selected from the 17-member Perturbed Physics Ensemble (PPE) using Hadley Centre Couple Model (HadCM3) based on the IPCC SRES A1B emission scenario. The future projections are analysed for three time slices 2011-2040 (near future), 2041-2070 (middle of the century) and 2071-2098 (distant future). Despite quantitative wet and cold bias, the model was able to resolve the seasonal pattern reasonably well. The model projects a decrease in rainfall in the near future and a progressive increase towards the end of the century. The projected change in rainfall is non-uniform, with increase over the southern plains and the middle mountains and decrease over the trans-Himalayan region. Simulation suggests that rainy days will be less frequent but more intense over the southern plains towards the end of the century. Further, the model projections indicate significant warming towards the end of the century. The rate of warming is slightly higher over the trans-Himalayan region during summer and over the southern plains during winter.
Hydro-Chemical Characterization of Glacial Melt Waters Draining from Langtang Valley, Nepal  [PDF]
Anisha Tuladhar, Rijan Bhakta Kayastha, Smriti Gurung, Ahuti Shrestha
Journal of Water Resource and Protection (JWARP) , 2015, DOI: 10.4236/jwarp.2015.78049
Abstract: A detailed analytical study of the physico-chemical parameters of melt water draining from glaciers of Langtang Valley with an elevation ranging from 1395 m a s l to 4200 m a s l in Rasuwa district, Nepal was carried out in order to study the seasonal and altitudinal variation in hydro-chemistry along the Langtang River and glacial melts from the Lirung and the Khimsung Glaciers. The study was carried out during 6 - 10 April and 30 June-3 July, 2014 at 11 sites. A total of 22 composite samples were collected. The concentration of cations and anions of the Langtang Valley were found in the order Ca2+ > K+ > Na+ > Mg2+ and \"\", respectively. Significant seasonal variation in electrical conductivity (EC), turbidity, dissolved oxygen (DO), calcium (Ca), sodium (Na), magnesium (Mg), chloride (Cl), sulphate (SO4) and total phosphorus (TP-PO4) and altitudinal variation in EC, total dissolved solids (TDS), DO and Na was found out. The concentrations of the heavy metals (As, Al, Mn, Zn, Cd, Cr) were below the detection limit except Fe (0.5 to 18.1 mg/l), which was highly variable. Calcium carbonate weathering was found out to be the major source of dissolved ions in the region. The elemental ratios (Ca/Si and K/Na) were typical of glacial melt water and the low Na/Cl and K/Cl ratios indicated major contribution from atmospheric precipitation to the observed dissolved ions of melt waters. The study showed an increase in the concentration of cations as compared to previous studies, which could be attributed to increasing weathering rates due to temperature increase. Elevated concentration of NO3 and TP-PO4 compared to previous studies show the effect of human impact in the region. Differences in the melt water composition between the debris covered and clean type glacier was found out.
RELATIONSHIP BETWEEN FLUVIAL CLASTIC SEDIMENT AND SOURCE ROCK ABUNDANCE IN RAPTI RIVER BASIN OF CENTRAL NEPAL HIMALAYAS
Tamrakar,Naresh Kazi; Shrestha,Madhusudan Bhakta;
Boletin de Geología , 2008,
Abstract: many tributaries from carbonate sedimentary, metamorphic and igneous rocks of the lesser himalayan and clastic sedimentary rocks of the sub-himalayan ranges carry gravelly sediments to the rapti river. river bar sediments were analyzed for composition and texture to evaluate downstream changes in properties, and to establish relationship between proportion of clasts and the abundance of rock types in the source areas. percent quartzite clast or granite clast increases whereas that of carbonate, schist or slate decreases along downstream. the largest grain size decreases downstream, whereas flatness index and sphericity tend to increase. despite of little diminish in relative abundance of rock types in source areas along the river, the relative proportion of corresponding clast type shows rapid reduction (e.g. slate or phyllite or carbonate clasts) or rapid enhancement (e.g. granite clast). the relationships of quartzite clast and schist clasts with their corresponding source rocks are statistically significant suggesting that these clasts can provide clue to source rock abundance. about 85 to 94% of the gravel clasts represent rock types of the lesser himalayan range suggesting that this range has been contributing enormous amount of sediments.
MORPHOMETRY AND SEDIMENT DYNAMICS OF THE CHURIYA RIVER AREA, SIWALIK RANGE IN NEPAL
Bhakta Shrestha,Madhusuda; Kazi Tamrakar,Naresh; Miyazaki,Toshitaka;
Boletin de Geología , 2008,
Abstract: the siwalik range of central nepal has weakly consolidated rocks with thin soil cover. being one of the several north-flowing subsequent tributaries, the churiya river originated from the southern uplifted range of the siwalik group. morphometry and hydraulic parameters of the churiya river basin (crb) were studied to know how capable is the river for carrying its sediment out of the basin. in many cases, hypsometric integral (hi) in 1st order watershed was lower (0.33-0.57) compared to that of 2nd and 3rd order watersheds (0.45-0.54) suggesting that it had been undergoing severe erosion. the surface flow in the churiya river appeared only during intense middle monsoon rainfall (june-august) and disappeared most of the time probably due to highly permeable riverbed. stream powers (ps) calculated from morphometric analyses of the drainage basin, and stream powers per unit bed area (ωb) computed from hydraulic data showed that 2nd order watershed in both cases were 2.5 times higher than 3rd order watershed. this suggests that stream powers of 2nd order watersheds had high potentiality of transporting sediments into 3rd order segment, where stream powers diminished due to reduction in slope, boundary shear stress, and increase of infiltration rate. although, stream powers reduced downstream (in 3rd order segment), they were quite high enough to flush out from the basin even the largest grain size (dmax) of the riverbeds during the period of high flows. therefore, sediment erosion should be controlled in the churiya river basin to reduce its impact on downstream segments and infrastructures.
Study of mercury (II) chloride tolerant bacterial isolates from Baghmati River with estimation of plasmid size and growth variation for the high mercury (II) resistant Enterobacter spp.
Vivek Bhakta Mathema,Bal Krishna Chand Thakuri,Mika Sillanp??,Reena Amatya Shrestha
Journal of Biotech Research , 2011,
Abstract: A total of three mercury resistant belonging to genus Enterobacter, Streptococcus and Pseudomonas were isolated from river banks of Baghmati in Kathmandu and were further categorized on the basis of their tolerance to mercury (II) chloride. Among all these isolates Enterobacter strain expressed highest degree of resistance towards Hg (II) chloride showing distinct growth in medium with upto 80 μg/ml of HgCl2 . Excessive slime production along with delayed pattern of growth and lower viability was observed for the isolate under increasing concentrations of Hg (II) supplemented liquid culture medium. Upon investigating total genetic content of this isolate, occurrence of plasmid with approximate 18 kb size and susceptible to mercuric chloride after plasmid curing suggests a plasmid mediated tolerance.
Optimization of RAPD-PCR conditions for the study of genetic diversity in Nepal’s Swertia chirayita (Roxb. Ex Fleming) H. Karst
Sangita Shrestha,Jaishree Sijapati,Neesha Rana,Diwa Malla,Prabha Regmi,Bhakta Raskoti
Himalayan Journal of Sciences , 2010, DOI: 10.3126/hjs.v6i8.2699
Abstract: Of the 30 species (including five varieties) of the genus Swertia in Nepal, nine have been reported to possess medicinal properties. Among these, S. chirayita is the most valuable species, with high demand in domestic and international markets. Nepal’s S. chirayita and related species are being recklessly exploited for commercial purposes. Two problems that have emerged with this lucrative market are (a) adulteration and fraudulent labeling of S. chirayita, and (b) depletion of S. chirayita and allied species from their natural habitats. To address the problem of adulteration and conservation, we studied molecular genetic diversity in S. chirayita populations and developed a molecular diagnostic tool for the purposes of authentication. We studied intra-specific genetic diversity in S. chirayita using Polymerase Chain Reaction (PCR)-based Random Amplified Polymorphic DNA (RAPD) technique. As a preliminary step, we identified optimal RAPD-PCR reaction and cycling conditions by varying PCR reaction parameters such as concentration of template DNA, MgCl2, dNTPs, primer, Taq DNA polymerase and RAPD-PCR programs. The optimized PCR reaction and cycling conditions were then used in subsequent RAPD profiling experiments for the study of genetic diversity within S. chirayita populations from various geographical locations. Genetic diversity characterization of S. chirayita populations at the molecular level would furnish information with significant applications in the conservation and sustainable utilization of S. chirayita and its allied species in Nepal.
Effect of Electron and/or Ion Nonthermality on Dust Acoustic Wave Propagation in a Complex Plasma in Presence of Positively Charged Dust Grains Generated by Secondary Electron Emission Process  [PDF]
Susmita Sarkar, Subrata Bhakta
Journal of Modern Physics (JMP) , 2016, DOI: 10.4236/jmp.2016.71008
Abstract: In this paper we have developed a model to study the role of both electron and ion nonthermalities on dust acoustic wave propagation in a complex plasma in presence of positively charged dust grains. Secondary electron emission from dust grains has been considered as the source of positive dust charging. As secondary emission current depends on the flux of primary electrons, nonthermality of primary electrons changes the expression of secondary emission current from that of earlier work where primary electrons were thermal. Expression of nonthermal electron current flowing to the positively charged dust grains and consequently the expression of secondary electron current flowing out of the dust grains have been first time calculated in this paper, whereas the expression for nonthermal ion current flowing to the positively charged dust grains is present in existing literature. Dispersion relation of dust acoustic wave has been derived. From this dispersion relation real frequency and growth rate of the wave have been calculated. Results have been plotted for different strength of nonthermalities of electrons and ions.
Correspondence in relation to the case report "Capnography as an aid in localizing the phrenic nerve in brachial plexus surgery. Technical note." published in May issue of Journal of Brachial Plexus and Peripheral Nerve Injury
Pradipta Bhakta
Journal of Brachial Plexus and Peripheral Nerve Injury , 2008, DOI: 10.1186/1749-7221-3-20
Abstract: Journal of Brachial Plexus and Peripheral Nerve Injury 2008, 3:14 (22 May 2008)Dear Editors,I want to thank the authors for this article explaining this innovative technique to identify phrenic nerve intraoperatively. This may be applied a good technique as replacement of currently available means. But after going through the article I found some doubts related to the actual correlation of diaphragmatic contraction with electrical stimulation of phrenic nerve.Authors have used an intravenous based anesthesia for their cases without muscle relaxation. They have not mentioned anything about the dose of the drug used or monitoring the depth or adequacy of anesthesia. Nor they mentioned anything about intraoperative ventilatory technique during maintenance of anesthesia. From the pattern of the capnogram presented in the report, I can assume that probably a controlled ventilatory technique was used in all the cases [1]. Authors have assumed that notches in the alveolar plateau part (phase III) of capnogram were because of diaphragmatic contraction elicited by electrical stimulation. But there are several reasons of appearance of notch in phase III of capnogram namely curare cleft, hiccup, premature respiratory effort by the patient during mechanical ventilation etc [1-3]. Though curare cleft is out of question in these cases, but premature respiratory effort provoked by painful electrical stimulation in the scenario of inadequate anesthesia and analgesia should have been considered as a possibility [1-3]. It is very well known that any electrical stimulation above 1–2 mA is very painful [4]. That is why it is advised to start electrical stimulation with lowest possible current and to increase it until stimulation is obtained. Though some or most of these painful responses can be reduced or abolished by use of anesthesia, painful stimulation like this under inadequate anesthesia can manifest as hemodynamic imbalance as well as premature respiratory effort. Appearance of
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