Dabhi V.K.,Dharmsinh Desai University |
Chaudhary S.,Ahmedabad University
Natural Computing | Year: 2015
Empirical modeling, which is a process of developing a mathematical model of a system from experimental data, has attracted many researchers due to its wide applicability. Finding both the structure and appropriate numeric coefficients of the model is a real challenge. Genetic programming (GP) has been applied by many practitioners to solve this problem. However, there are a number of issues which require careful attention while applying GP to empirical modeling problems. We begin with highlighting the importance of these issues including: computational efforts in evolving a model, premature convergence, generalization ability of an evolved model, building hierarchical models, and constant creation techniques. We survey and classify different approaches used by GP researchers to deal with the mentioned issues. We present different performance measures which are useful to report the results of analysis of GP runs. We hope this work would help the reader by facilitating to understand key concepts and practical issues of GP and steering in selection of an appropriate approach to solve a particular issue effectively. © 2014, Springer Science+Business Media Dordrecht.
Magdolenova Z.,Norwegian Institute For Air Research |
Collins A.,University of Oslo |
Kumar A.,Ahmedabad University |
Dhawan A.,Ahmedabad University |
And 3 more authors.
Nanotoxicology | Year: 2014
Engineered nanoparticles (NPs) are widely used in different technologies but their unique properties might also cause adverse health effects. In reviewing recent in vitro and in vivo genotoxicity studies we discuss potential mechanisms of genotoxicity induced by NPs. Various factors that may influence genotoxic response, including physico-chemical properties and experimental conditions, are highlighted. From 4346 articles on NP toxicity, 112 describe genotoxicity studies (94 in vitro, 22 in vivo). The most used assays are the comet assay (58 in vitro, 9 in vivo), the micronucleus assay (31 in vitro, 14 in vivo), the chromosome aberrations test (10 in vitro, 1 in vivo) and the bacterial reverse mutation assay (13 studies). We describe advantages and potential problems with different methods and suggest the need for appropriate methodologies to be used for investigation of genotoxic effects of NPs, in vitro and in vivo. © 2014 Informa UK, Ltd.
Karakoti A.S.,Battelle |
Shukla R.,Ahmedabad University |
Shanker R.,Ahmedabad University |
Singh S.,Ahmedabad University
Advances in Colloid and Interface Science | Year: 2015
Quantum dots are a group of inorganic nanomaterials exhibiting exceptional optical and electronic properties which impart distinct advantages over traditional fluorescent organic dyes in terms of tunable broad excitation and narrow emission spectra, signal brightness, high quantum yield and photo-stability. Aqueous solubility and surface functionalization are the most common problems for QDs employed in biological research. This review addresses the recent research progress made to improve aqueous solubility, functionalization of biomolecules to QD surface and the poorly understood chemistry involved in the steps of bio-functionalization of such nanoparticles. © 2014 Elsevier B.V. All rights reserved.
Sharma V.,Indian Institute of Toxicology Research |
Sharma V.,University of Bradford |
Sharma V.,University of North Carolina at Chapel Hill |
Anderson D.,University of Bradford |
And 2 more authors.
Apoptosis | Year: 2012
The wide scale use of Zinc oxide (ZnO) nanoparticles in the world consumer market makes human beings more prone to the exposure to ZnO nanoparticles and its adverse effects. The liver, which is the primary organ of metabolism, might act as a major target organ for ZnO nanoparticles after they gain entry into the body through any of the possible routes. Therefore, the aim of the present study was to assess the apoptotic and genotoxic potential of ZnO nanoparticles in human liver cells (HepG2) and the underlying molecular mechanism of its cellular toxicity. The role of dissolution in the toxicity of ZnO nanoparticles was also investigated. Our results demonstrate that HepG2 cells exposed to 14-20 lg/ml ZnO nanoparticles for 12 h showed a decrease in cell viability and the mode of cell death induced by ZnO nanoparticles was apoptosis. They also induced DNA damage which was mediated by oxidative stress as evidenced by an increase in Fpg sensitive sites. Reactive oxygen species triggered a decrease in mitochondria membrane potential and an increase in the ratio of Bax/ Bcl2 leading to mitochondria mediated pathway involved in apoptosis. In addition, ZnO nanoparticles activated JNK, p38 and induced p53Ser15 phosphorylation. However, apoptosis was found to be independent of JNK and p38 pathways. This study investigating the effects of ZnO nanoparticles in human liver cells has provided valuable insights into the mechanism of toxicity induced by ZnO nanoparticles. © Springer Science+Business Media, LLC 2012.
Kumar A.,Ahmedabad University |
Dhawan A.,Ahmedabad University |
Dhawan A.,Indian Institute of Toxicology Research
Archives of Toxicology | Year: 2013
Nanoscience and nanotechnology have seen an exponential growth over the past decade largely due to the unique properties of engineered nanoparticles (ENPs), advances in ENP synthesis, and imaging or analysis tools. The unique properties such as high surface area to volume ratio, abundant reactive sites on the surface, large fraction of atoms located on the exterior face have made these novel materials the most sought after for consumer and industrial applications. This significant increase in the ENP containing consumer products has also enhanced the chances of human and environmental exposure. Humans get exposed to ENPs at various steps of its synthesis (laboratory), manufacture (industry), use (consumer products, devices, medicines, etc.) and through the environment (contaminated water, aerosolized particles, and disposal). Such exposures to ENPs are known to induce genotoxicity, cytotoxicity, and carcinogenicity in biological system. This is attributed to several factors, such as direct interaction of ENPs with the genetic material, indirect damage due to reactive oxygen species generation, release of toxic ions from soluble ENPs, interaction with cytoplasmic/nuclear proteins, binding with mitotic spindle or its components, increased oxidative stress, disturbance of cell cycle checkpoint functions, inhibition of antioxidant defense, and many others. The present review describes an overview of in vitro and in vivo genotoxicity studies with ENPs, advantages and potential problems associated with the methods used in genotoxicity assessment, and the need for appropriate method and approach for risk assessment of ENPs. © 2013 Springer-Verlag Berlin Heidelberg.
Bhatt J.S.,Dhirubhai Ambani Institute of ICT |
Joshi M.V.,Dhirubhai Ambani Institute of ICT |
Raval M.S.,Ahmedabad University
IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing | Year: 2014
In this paper, we propose a two-step Bayesian approach to handle the ill-posed nature of the unmixing problem for accurately estimating the abundances. The abundances are dependent on the scene contents and they represent mixing proportions of the endmembers over an area. In this work, a linear mixing model (LMM) is used for the image formation process in order to derive the data term. In the first step, a Huber-Markov random field (HMRF)-based prior distribution is assumed to model the dependencies within the abundances across the spectral space of the data. The threshold used in the HMRF prior is derived from an initial estimate of abundances obtained using the matched filters. This makes the HMRF prior data-driven, i.e., dHMRF. Final abundance maps are obtained in the second step within a maximum a posteriori probability (MAP) framework, and the objective function is optimized using the particle swarm optimization (PSO). Theoretical analysis is carried out to show the effectiveness of the proposed method. The approach is evaluated using the synthetic and real AVIRIS Cuprite data. The proposed method has the following advantages. 1) The estimated abundances are resistant to noise since they are based on an initial estimate that has high signal-to-noise ratio (SNR). 2) The variance in the abundance maps is well preserved since the threshold in the dHMRF is derived from the data. © 2014 IEEE.
Singh S.,Ahmedabad University
BioImpacts | Year: 2013
Gene therapy has been recently shown as a promising tool for cancer treatment as nanotechnology-based safe and effective delivery methods are developed. Generally, genes are wrapped up in extremely tiny nanoparticles which could be taken up easily by cancer cells, not to their healthy neighboring cells. Several nanoparticle systems have been investigated primarily to address the problems involved in other methods of gene delivery and observed improved anticancer efficacy suggesting that nanomedicine provides novel opportunities to safely deliver genes, thus treat cancer. In this review, various nanoparticle types and related strategies, used in gene delivery for cancer treatment, have been discussed. © 2013 by Tabriz University of Medical Sciences.
Singh R.,Ahmedabad University |
Singh S.,Ahmedabad University
Colloids and Surfaces B: Biointerfaces | Year: 2015
Cerium oxide nanoparticles (CeNPs) have been recently shown to scavenge reactive oxygen and nitrogen species (ROS and RNS) in different experimental model systems. CeNPs (3+) and CeNPs (4+) have been shown to exhibit superoxide dismutase (SOD) and catalase mimetic activity, respectively. Due to their nanoscale dimension, CeNPs are expected to interact with the components of biologically relevant buffers and medium, which could alter their catalytic properties. We have demonstrated earlier that CeNPs (3+) interact with phosphate and lose the SOD activity. However, very little is known about the interaction of CeNPs (4+) with the phosphate and other anions, predominantly present in biological buffers and their effects on the catalase mimetic-activity of these nanoparticles. In this study, we report that catalase mimetic-activity of CeNPs (4+) is resistant to the phosphate anions, pH changes and composition of cell culture media. Given the abundance of phosphate anions in the biological system, it is likely that internalized CeNPs would be influenced by cytoplasmic and nucleoplasmic concentration of phosphate. © 2015 Elsevier B.V.
Sharma R.,Ahmedabad University
International Journal of Power Electronics and Drive Systems | Year: 2013
In this paper, a new soft switched cell that overcomes most of the drawbacks of the normal "hard switched-pulse width modulation" converter is proposed to contrive a new family of soft switched PWM converters. All of the semiconductor devices in this converter are turned on and off under exact or near zero voltage switching (ZVS) and/or zero current switching (ZCS). No additional voltage and current stresses on the main switch and main diode occur. A push-pull converter equipped with the proposed snubber cell is analyzed in detail. The predicted operation principles and theoretical analysis of the presented converter are verified with a prototype of a 50W PWM push-pull multi-output converter with insulated MOSFET and for regulation of slave outputs magnetic amplifier post regulators are considered as post regulators. Moreover; this multioutput converter has a simple structure, low cost, and ease of control circuitry. © 2013 Institute of Advanced Engineering and Science. All rights reserved.
Agency: Cordis | Branch: FP7 | Program: CP-IP | Phase: NMP-2010-1.3-1 | Award Amount: 13.15M | Year: 2011
The growing development, production and use of engineered nanomaterials and associated products will increase exposure of both humans and ecosystems to these new materials. However, current knowledge is still incomplete and established test methods are as yet inappropriate to reliably assess the extent of exposure and risk of materials at the nano-scale. There is an urgent need to develop methods to overcome the current limitations of existing hazard and risk assessment schemes and to generate the body of reference data needed as the basis for regulative requirements and for measures to safeguard production, application and the disposal of nanomaterials. The proposed project will mobilize the critical mass of international scientific knowledge and technical expertise required to address these questions. Current analytical and toxicity test methods and models will be put to test and subjected to rigorous intercalibration and validation. Where necessary, methods and test materials will be modified, adapted and validated, and new reliable reference methods developed, in cooperation with international standardisation bodies and the concerned industry, to support both pre and co-normative activities and to make the applicability of existing RA and LCA schemes to ENPs more reliable. The feasibility of validated measurement, characterization and test methods will be assessed by selected case studies to help the significant improvement of the performance of existing exposure monitoring systems as well as the development of new risk management and reduction strategies.