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Search Results: 1 - 10 of 1600 matches for " Tiwari Ashutosh "
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High-Resolution Monsoon Records Since Last Glacial Maximum: A Comparison of Marine and Terrestrial Paleoarchives from South Asia
Manish Tiwari,Ashutosh K. Singh,Rengaswamy Ramesh
Journal of Geological Research , 2011, DOI: 10.1155/2011/765248
Abstract: Agricultural production and the availability of fresh water in Indian subcontinent critically depend on the monsoon rains. Therefore it is vital to understand the causal mechanisms underlying the observed changes in the Indian monsoon in the past. Paleomonsoon reconstructions show that the water discharge from the Ganges-Brahmaputra River system to the Bay of Bengal was maximum in the early to mid-Holocene; data from the Western Arabian Sea and Omanian speleothems indicate declining monsoon winds during the Holocene, whereas records from the South West Monsoon (SWM) precipitation dominated eastern Arabian Sea show higher runoff from the Western Ghats indicating gradually increasing monsoon precipitation during the Holocene. Thus there exists considerable spatial variability in the monsoon in addition to the temporal variability that needs to be assessed systematically. Here we discuss the available high resolution marine and terrestrial paleomonsoon records such as speleothems and pollen records of the SWM from important climatic regimes such as Western Arabian Sea, Eastern Arabian Sea, Bay of Bengal to assess what we have learnt from the past and what can be said about the future of water resources of the subcontinent in the context of the observed changes. 1. Introduction The Indian economy is based on agriculture, which mostly depends on the monsoon rain and to some extent on river flow and ground water resources. In the absence of monsoon that brings adequate rain, crop yield is reduced and due to recurrent droughts there may even be severe shortage of drinking water. The water resources of India comprise rivers, lakes, and ground water aquifers and the amount of water they hold is linked to the rainfall on the one hand and human exploitation on the other. Thus it is important to have a correct long-term forecast of the monsoon that can help in the proper management of our water resources [1]. Monsoon prediction is seriously hampered by the nonavailability of past data, which is limited to about hundred years [2]. It is very difficult to predict the monsoon without understanding its full variability. Generating quantitative paleomonsoon data using available, dateable, natural archives, such as deep sea and lake sediments, varved sediments, and speleothems is a starting point towards this end [3–6]. Monsoon is a term derived from an Arabic word “Mausim” meaning weather. It is technically applied to the seasonal reversal of winds in the Indian subcontinent and Africa, especially in the Arabian Sea, due to land-sea thermal and pressure contrast. It is
Clomiphene Citrate Induces ROS-Mediated Apoptosis in Mammalian Oocytes  [PDF]
Shail K. Chaube, Tulsidas G. Shrivastav, Shilpa Prasad, Meenakshi Tiwari, Anima Tripathi, Ashutosh N. Pandey, Karuppanan V. Premkumar
Open Journal of Apoptosis (OJApo) , 2014, DOI: 10.4236/ojapo.2014.33006
Abstract: The clomiphene citrate (CC), a nonsteroidal triphenylethylene compound, is a first line of medicine used for the induction of ovulation in anovulatory women worldwide. In spite of high ovulation induction with the use of CC, the pregnancy rate is much lower. Such a discrepancy could be due to the peripheral anti-estrogenic effect of CC, particularly at the level of ovary, endometrium and cervical mucus. CC induces ovulation by binding to the estrogen receptors and generates hypoestrogrnic state in hypothalamus leading to release of pituitary gonadotropins. CC may have a direct effect at the level of ovary but the molecular mechanism remains unclear. Animal studies suggest that the CC induces apoptosis in granulosa cells and results hypoestrogenic state in the ovary. Reduced estradiol 17β level in the ovary affects development and maturation of oocyte leading to oocyte apoptosis. Further, CC increases hydrogen peroxide (H2O2) level and thereby bax protein expression and DNA fragmentation in cumulus-granulosa cells as well as in oocytes. The exogenous supplementation of either estradiol 17β or melatonin reduces H2O2 level in ovary, delays meiotic cell cycle progression in oocyte and protects oocyte apoptosis. Hence, supplementation of estradiol 17β or melatonin along with CC could be beneficial to protect granulosa cell as well as oocyte apoptosis and inhibit deterioration of oocyte quality. Thus, maintenance of oocyte quality may overcome the adverse effect caused due to CC treatment during infertility management.
A novel strategy for efficient production of anti-V3 human scFvs against HIV-1 clade C
Kumar Rajesh,Andrabi Raiees,Tiwari Ashutosh,Prakash Somi Sankaran
BMC Biotechnology , 2012, DOI: 10.1186/1472-6750-12-87
Abstract: Background Production of human monoclonal antibodies that exhibit broadly neutralizing activity is needed for preventing HIV-1 infection, however only a few such antibodies have been generated till date. Isolation of antibodies by the hybridoma technology is a cumbersome process with fewer yields. Further, the loss of unstable or slowly growing clones which may have unique binding specificities often occurs during cloning and propagation and the strongly positive clones are often lost. This has been avoided by the process described in this paper, wherein, by combining the strategy of EBV transformation and recombinant DNA technology, we constructed human single chain variable fragments (scFvs) against the third variable region (V3) of the clade C HIV-1 envelope. Results An antigen specific phage library of 7000 clones was constructed from the enriched V3- positive antibody secreting EBV transformed cells. By ligation of the digested scFv DNA into phagemid vector and bio panning against the HIV-1 consensus C and B V3 peptides followed by random selection of 40 clones, we identified 15 clones that showed V3 reactivity in phage ELISA. DNA fingerprinting analysis and sequencing showed that 13 out of the 15 clones were distinct. Expression of the positive clones was tested by SDS-PAGE and Western blot. All the 13 anti-V3 scFvs showed cross-reactivity against both the clade C and B V3 peptides and did not show any reactivity against other unrelated peptides in ELISA. Preliminary neutralization assays indicated varying degrees of neutralization of clade C and B viruses. EBV transformation, followed by antigen selection of lines to identify specific binders, enabled the selection of phage from un-cloned lines for scFv generation, thus avoiding the problems of hybridoma technology. Moreover, as the clones were pretested for antigen binding, a comparatively small library sufficed for the selection of a considerable number of unique antigen binding phage. After selection, the phage clones were propagated in a clonal manner. Conclusions This strategy can be efficiently used and is cost effective for the generation of diverse recombinant antibodies. This is the first study to generate anti-V3 scFvs against HIV-1 Clade C.
Recurrent Vertigo: Is it Takayasu's Arteritis?
Tiwari Ashutosh,Kumar Nilesh,Varshney Ankur Nandan,Behera Dibyaranjan
Case Reports in Vascular Medicine , 2013, DOI: 10.1155/2013/851352
Abstract:
Acute Transverse Myelitis (Ascending Myelitis) as the Initial Manifestation of Japanese Encephalitis: A Rare Presentation
Varshney Ankur Nandan,Kumar Nilesh,Behera Dibyaranjan,Tiwari Ashutosh
Case Reports in Infectious Diseases , 2013, DOI: 10.1155/2013/487659
Abstract:
Phase Coexistence and the Structure of the Morphotropic Phase Boundary Region in (1-x)Bi(Mg1/2Zr1/2)O3-xPbTiO3 Piezoceramics
Rishikesh Pandey,Ashish Tiwari,Ashutosh Upadhyay,Akhilesh Kumar Singh
Physics , 2013, DOI: 10.1016/j.actamat.2014.05.023
Abstract: Structure of the morphotropic phase and the phase coexistence region has been investigated in (1-x)Bi(Mg1/2Zr1/2)O3-xPbTiO3 ceramics. The structure is cubic with space group Pm3m for the compositions with x<0.57 and tetragonal with space group P4mm for the compositions with x>0.59. For the compositions with 0.56
Monitoring Forests: A New Paradigm of Remote Sensing & GIS Based Change Detection  [PDF]
Subhash Ashutosh
Journal of Geographic Information System (JGIS) , 2012, DOI: 10.4236/jgis.2012.45051
Abstract: Remote sensing has emerged as the main tool for mapping and monitoring of forest resources globally. In India, this technological tool is in use for biennial monitoring of forest cover of the country for the last 25 years. Among the numerous applications of remote sensing in forest management, change detection is the one which is most frequently used. In this paper, a new paradigm of change detection has been presented in which change of vegetation in a grid (a square shaped unit area) is the basis of change analysis instead of change at the pixel level. The new method is a simpler approach and offers several advantages over the conventional approaches of remote sensing based change detection. The study introduces an index termed as ‘Grid Vegetation Change Index (GVCI)’, its numerical value gives quantified assessment of the degree of change. The minus value of GVCI indicates loss or negative change and similarly positive value vice versa. By applying the GVCI on a pair of remotely sensed images of two dates of an area, one can know degree of vegetation change in every unit area (grid) of the large landscape. Based on the GVCI values, one can select those grids which show significant changes. Such ‘candidate grids with significant changes’ may be shortlisted for ground verification and studying the causes of change. Since the change identification is based on the index value, it is free from human subjectivity or bias. Though there may be some limitations of the methodology, the GVCI based approach offers an operational application for monitoring forests in India and elsewhere for complete scanning of forest areas to pointedly identify change locations, identifying the grids with significant changes for objective and discrete field inspections with the help of GPS. It also offers a method to monitor progress of afforestation and conservation schemes, monitor habitats of wildlife areas and potential application in carbon assessment methodologies of CDM and REDD+.
Proposal for Plasma Wave Oscillator  [PDF]
Ashutosh Sharma
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2012, DOI: 10.4236/jemaa.2012.410057
Abstract: Generation of radiation by laser pulses in uniform plasma is generally minimal. However, if one considers propagation in corrugated plasma channels, the condition for radiation generation can be met due to the inhomogeneity of the plasma channel and the presence of guided waves with subluminal phase velocities. For establishing a large amplitude plasma wave driven by moderate-power laser, one has to implement a distributed-feedback structure into the plasma (Plasma Wave Oscillator) with the feedback matching the plasma resonance. In this note the theoretical analysis for plasma waves driven by moderate-power laser for corrugated waveguide filled with pre-ionized hydrogen plasma has been developed. The growth of amplitude of plasma waves in corrugated structure, coupled to the laser and sideband fields has been investigated. The four coupled equations corresponding to laser field, sideband field and forward and backward plasma waves can be numerically solved for various parameters of the laser field, plasma density, and corrugated structure to arrive at experimental design of the Plasma Wave Oscillator, which may be used for the generation of radiation and particle acceleration.
A Review Study on Amplification of X-Ray Free Electron Laser Pulse in Plasma  [PDF]
Ashutosh Sharma
Journal of Modern Physics (JMP) , 2012, DOI: 10.4236/jmp.2012.312250
Abstract:

In view of X-ray Free Electron Laser (XFEL) intensity prospects, we reviewed the past and recent work in view of amplification of powerful XFEL laser pulse to achieve intensity in the regime of high field science. We report here some of the relevant work investigated in this field and predicted further scalings and possibilities for XFEL pulse amplification.

Self-Thomson Backscattering of Ultra-Intense Laser from Thin Foil Target  [PDF]
Ashutosh Sharma
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2013, DOI: 10.4236/jemaa.2013.51007
Abstract:

An electromagnetic solitary structure in attosecond regime is identified, costreaming with electron bunch. It is observed via nonlinear process of Self-Thomson backscattering of an ultra-intense laser from thin foil target. The process is termed as Self-Thomson Backscattering since the counter propagating electron sheets are generated by the drive laser itself. The radiation pressure acceleration model is considered for the interaction of a super-intense linearly polarized laser pulse with a thin foil in one-dimensional (1D) particle-in-cell (PIC) simulations.

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