FINITE ELEMENT MODEL TO STUDY TWO DIMENSIONAL UNSTEADY STATE CYTOSOLIC CALCIUM DIFFUSION

Tewari, Shivendra Gajraj,Pardasani, Kamal Raj The Korean Society for Computational and Applied M 2011 Journal of applied mathematics & informatics Vol.29 No.1

Calcium is a vital second messenger for signal transduction in neurons. Calcium plays an important role in almost every part of the human body but in neuronal cytosol, it is of utmost importance. In order to understand the calcium signaling mechanism in a better way a finite element model has been developed to study the flow of calcium in two dimensions with time. This model assumes EBA (Excess Buffering Approximation), incorporating all the important parameters like time, association rate, influx, buffer concentration, diffusion constant etc. Finite element method is used to obtain calcium concentration in two dimensions and numerical integration is used to compute effect of time over 2-D Calcium profile. Comparative study of calcium signaling in two dimensions with time is done with other important physiological parameters. A MATLAB program has been developed for the entire problem and simulated on an x64 machine to compute the numerical results.

Total Wood Volume Equations for Tectona Grandis Linn F. Stands in Gujarat, India

Tewari, Vindhya Prasad,Singh, Bilas Institute of Forest Science 2018 Journal of Forest Science Vol.34 No.4

Tectona grandis (teak) is one of the most important timber species worldwide and India is one of the major teak growing countries. Though some volume equations were developed for teak in India but the models developed were neither evaluated using robust statistical criteria nor validated. Hence, the objective of this study was to develop statistically tested appropriate volume equation to predict total wood volume (over- and under-bark) for teak trees in Gujarat. A total of 41 trees with age varying from 15 to 33 years and diameter at breast height (dbh) from 7.3 to 30.8 cm were felled for the purpose. Linear and non-linear equations were used to model the relationship of the total wood volume with respect to dbh and total height. The equations tested mostly fitted well to the data. Model evaluation and validation indicated that models should be calibrated with local data for greater accuracy in the prediction.

Studies on Interaction of Essential Metal Ions with Bioactive Ligands

Tewari, Brij Bhushan Korean Chemical Society 2004 Bulletin of the Korean Chemical Society Vol.25 No.6

Complexation reactions of nitrilotriacetate (NTA) and penicillamine with $Cu^{2+}$ and $Co^{2+}$ have been studied in solution phase using paper electrophoresis technique. The stability constants of the complexes Cu(II)-nitrilotriacetate-penicillamine and Co(II)-nitrilotriacetate-penicillamine have been found to be $6.64{\pm}0.03\;and\;5.86{\pm}0.05$ (logarithm stability constant values), respectively at 35$^{\circ}C$ and ionic strength 0.1 M.

Paper Ionophoretic Technique in the Study of Mixed Complexes

Tewari, Brij Bhushan Korean Chemical Society 2002 Bulletin of the Korean Chemical Society Vol.23 No.5

Stability constants of complexes of aluminium(III) and thorium(IV) with methionine and cysteine have been determined by modified paper electrophoretic technique at $\mu$ = 0.1 M. The proportion of ionic species of methionine and cysteine were varied by changing pH of background electrolyte. The stability constants of the complexes metal-methionine-cysteine have been found to be 4.31 ± 0.12 and 5.40 ± 0.19 (log K values) for $Al^{3+}\;and\;Th^{4+} $ complexes, at temperature 35 ${^{\circ}C}$, respectively.

Variable Density Yield Model for Irrigated Plantations of Dalbergia sissoo Grown Under Hot Arid Conditions in India

Tewari, Vindhya Prasad Institute of Forest Science 2012 Journal of Forest Science Vol.28 No.4

Yield tables are a frequently used data base for regional timber resource forecasting. A normal yield table is based on two independent variables, age and site (species constant), and applies to fully stocked (or normal) stands while empirical yield tables are based on average rather than fully stocked stands. Normal and empirical yield tables essentially have many limitations. The limitations of normal and empirical yield tables led to the development of variable density yield tables. Mathematical models for estimating timber yields are usually developed by fitting a suitable equation to observed data. The model is then used to predict yields for conditions resembling those of the original data set. It may be accurate for the specific conditions, but of unproven accuracy or even entirely useless in other circumstances. Thus, these models tend to be specific rather than general and require validation before applying to other areas. Dalbergia sissoo forms a major portion of irrigated plantations in the hot desert of India and is an important timber tree species where stem wood is primarily used as timber. Variable density yield model is not available for this species which is very crucial in long-term planning for managing the plantations on a sustained basis. Thus, the objective of this study was to develop variable density yield model based on the data collected from 30 sample plots of D. sissoo laid out in IGNP area of Rajasthan State (India) and measured annually for 5 years. The best approximating model was selected based on the fit statistics among the models tested in the study. The model develop was evaluated based on quantitative and qualitative statistical criteria which showed that the model is statistically sound in prediction. The model can be safely applied on D. sissooo plantations in the study area or areas having similar conditions.

Silicon-Nanocrystal-Coated Silica Microsphere Thermooptical Switch

Tewary, Anuranjita,Digonnet, Michel J. F.,Sung, Joo-Yeon,Shin, Jung H.,Brongersma, Mark L. IEEE 2006 IEEE journal on selected topics in quantum electro Vol.12 No.6

<P>We report on a low-switching-energy, all-optical fiber switch that consists of a silica microsphere resonator coated with a silica layer containing silicon nanocrystals. A signal at 1450 nm and a pump at 488 nm are coupled into the microsphere through a tapered fiber. When a pump pulse is launched into the sphere, it is absorbed by the nanocrystal layer, causing the sphere to heat up and change its refractive index. The index change can be exploited to switch the signal by shifting the microsphere resonance. A resonance wavelength shift of 5 pm, sufficient to fully switch the signal, was observed with a pump pulse energy of only 85 nJ. The rise time of the switch was ~25 ms (limited by the pump peak power) and its fall time was ~30 ms (limited by the sphere's thermal time constant). The product of the switching peak power (3.4 mu W) and the device's characteristic dimension (a diameter of 150 mum) is 5.1times10<SUP>-10</SUP> Wm, one of the lowest values reported for an all-optical fiber switch</P>

Development of a Stand Density Management Diagram for Teak Forests in Southern India

Tewari, Vindhya Prasad,Alvarez-Gonz, Juan Gabriel Institute of Forest Science 2014 Journal of Forest Science Vol.30 No.3

Stand Density Diagrams (SDD) are average stand-level models which graphically illustrate the relationship between yield, density and mortality throughout the various stages of forest development. These are useful tools for designing, displaying and evaluating alternative density regimes in even-aged forest ecosystems to achieve a desired future condition. This contribution presents an example of a SDD that has been constructed for teak forests of Karnataka in southern India. The relationship between stand density, dominant height, quadratic mean diameter, relative spacing and stand volume is represented in one graph. The relative spacing index was used to characterize the population density. Two equations were fitted simultaneously to the data collected from 27 sample plots measured annually for three years: one relates quadratic mean diameter with stand density and dominant height while the other relates total stand volume with quadratic mean diameter, stand density and dominant height.

Nitric oxide retards xanthine oxidase-mediated superoxide anion generation in Phalaenopsis flower: an implication of NO in the senescence and oxidative stress regulation

Tewari, Rajesh Kumar,Kumar, Praveen,Kim, Soohyun,Hahn, Eun-Joo,Paek, Kee-Yoeup Springer-Verlag 2009 Plant cell reports Vol.28 No.2

Significant Association of Metabolic Indices, Lipid Profile, and Androgen Levels with Prostate Cancer

Tewari, Reshu,Chhabra, Mohini,Natu, Shankar Madhavan,Goel, Apul,Dalela, Divakar,Goel, Madhu Mati,Rajender, Singh Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.22

Objectives: To compare the metabolic indices, lipid profile, androgens, and prostate specific antigen between prostate cancer and BPH and between grades of prostate cancer in a cross-sectional study. Materials and Methods: The study enrolled 95 cases of prostate cancer and 95 cases of benign prostatic hyperplasia (BPH). Prostate gland volume was measured using transrectal ultrasound. We compared insulin, testosterone, dihydrotestosterone, prostate specific antigen levels and lipid profile between prostate cancer of different grades and BPH. Further, prostate cancer patients were classified into low grade and high grade. Unpaired t-test for normally distributed variables and Man-Whitney U test for non-normal variables were used to assess differences. Results: We found that prostate cancer patients had significantly higher levels of insulin, testosterone, PSA, cholesterol, triglycerides, low-density lipoprotein (LDL) and very low-density lipoprotein (VLDL) in comparison to their BPH counterparts. Higher levels of these parameters also correlated with a higher grade of the disease. Conclusions: We conclude that higher levels of insulin, testosterone, PSA, and cholesterol correlate with a higher risk of prostate cancer, and also with a higher grade of the disease.

Peripheral Blood Lymphocytes as In Vitro Model to Evaluate Genomic Instability Caused by Low Dose Radiation

Tewari, Shikha,Khan, Kainat,Husain, Nuzhat,Rastogi, Madhup,Mishra, Surendra P,Srivastav, Anoop K Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.4

Diagnostic and therapeutic radiation fields are planned so as to reduce side-effects while maximising the dose to site but effects on healthy tissues are inevitable. Radiation causes strand breaks in DNA of exposed cells which can lead to chromosomal aberrations and cause malfunction and cell death. Several researchers have highlighted the damaging effects of high dose radiation but still there is a lacuna in identifying damage due to low dose radiation used for diagnostic purposes. Blood is an easy resource to study genotoxicity and to estimate the effects of radiation. The micronucleus assay and chromosomal aberration can indicate genetic damage and our present aim was to establish these with lymphocytes in an in vitro model to predict the immediate effects low dose radiation. Blood was collected from healthy individuals and divided into 6 groups with increasing radiation dose i.e., 0Gy, 0.10Gy, 0.25Gy, 0.50Gy, 1Gy and 2Gy. The samples were irradiated in duplicates using a LINAC in the radiation oncology department. Standard protocols were applied for chromosomal aberration and micronucleus assays. Metaphases were stained in Giemsa and 200 were scored per sample for the detection of dicentric or acentric forms. For micronuclei detection, 200 metaphases. Giemsa stained binucleate cells per sample were analysed for any abnormality. The micronuclei (MN) frequency was increased in cells exposed to the entire range of doses (0.1-2Gy) delivered. Controls showed minimal MN formation ($2.0%{\pm}0.05$) with triple MN ($5.6%{\pm}2.0$) frequency at the lowest dose. MN formation increased exponentially with the radiation dose thereafter with a maximum at 2Gy. Significantly elevated numbers of dicentric chromosomes were also observed, even at doses of 0.1-0.5Gy, compared to controls, and acentric chromosomes were apparent at 2Gy. In conclusion we can state that lymphocytes can be effectively used to study direct effect of low dose radiation.