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Search Results: 1 - 10 of 151880 matches for " H Krishna "
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Biochemical alterations induced by the acute exposure to combination of chlorpyrifos and lead in Wistar rats
H Krishna,AV Ramachandran
Biology and Medicine , 2009,
Abstract: Chlorpyrifos, a well known organophosphorus insecticide and heavy metal lead, was challenged to Wistar rats tostudy their interactive effects on biochemical parameters (clinical pathology) after acute exposure via oral gavaging.Hematology and clinical chemistry parameters were estimated after 14 days of exposure. In addition, serum butryland RBC cholinesterase was estimated on days 3rd and 15th of experimentation. The study was conducted using twodifferent dose levels of chlorpyrifos and lead acetate and grouped into seven groups. The parameters of hematologyand serum chemistry were analysed through automatic analyzers. No treatment related or interactive effects werenoticed in hematology values except for the reduced RBC, Hb content and HCT values in lead treated animals at1000mg/kg. A significant decrease in both serum and RBC cholinesterase enzymes were noticed in animals treatedwith chlorpyrifos at 50 mg/kg and in combination group (chlorpyrifos 50 + lead 1000 mg/kg), and increased inhibitionalong with delayed recovery was observed in the animals of combination group (i.e., chlorpyrifos plus lead).Chlorpyrifos in presence of lead increases the inhibition of both serum and RBC cholinesterase enzymes. The longlasting or persistence effects of CPF along with and lead may result in impaired cognitive functions of brainconsidering the role of cholinesterases in neuronal architecture of brain and other normal functioning of nervoussystem. Therefore, simultaneous exposure to a combination of chlorpyrifos and lead is considered to be moredangerous than to an exposure of either alone. In addition, serum chemistry revealed changes in concentrations ofglucose and sodium owing to lead treatment.
Assessment of chlorpyrifos and lead acetate combination on neurobehavioral aspects in Wistar rats after subchronic dietary exposure
H Krishna,AV Ramachandran
Biology and Medicine , 2009,
Abstract: Organophosphorus insecticide, chlorpyrifos, and heavy metal, lead, were studied for their interactive effects onneurobehavioral aspects in Wistar rats when exposed for a period of 90 consecutive days through experimental diet.The tests used for the assessment of neurobehavioral changes were include functional observation battery, gripstrength measurement, foot splay measurement and motor activity. The study was designed using two different doselevels of chlorpyrifos and lead acetate and grouped into seven groups including concurrent controls. Neurobehavioralobservations were performed at the end of 4 and 13 weeks of exposure and after 4 weeks of recovery period.Repeated dietary exposure at a dose level of 10 ppm of chlorpyrifos (i.e., equivalent to 1mg/kg body weight/day) andin a combination of 10 ppm chlorpyrifos plus 500 ppm of lead acetate (i.e., equivalent to 44.0mg/kg body weight/day)to groups of animals revealed mild cholinergic symptoms and decreased rearing counts at the end of week 4. Inaddition, combination group animals (Chorpyrifos plus Lead) treated at the low dose level (Chlorpyrisfos-1ppm andlead-50 ppm) also revealed reduction in the vertical movements. The lack of persistence and/or cumulative effects ofthese changes after 13 weeks of exposure is due to tolerance induced by the chlorpyrifos. The rearing movementsmeasured in the open field are considered to be more indicative of exploratory behaviour and emotional tendenciesthan of general motor activity. A decrease in rearing counts of combination group animals (Chorpyrifos plus Lead)treated at the low dose level after week 4 was noticeable, irrespective of sex, suggests that even at low dose levels,the combination of chlorpyrifos and lead produces behavioral changes. However, many higher levels of tests fordetection of cognitive functions should also be considered. No other behavioral changes were noticed in the studiedbehavioral tests.
Software Reuse in Cardiology Related Medical Database Using K-Means Clustering Technique  [PDF]
M. Bhanu Sridhar, Y. Srinivas, M. H. M. Krishna Prasad
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.59081
Abstract: Software technology based on reuse is identified as a process of designing software for the reuse purpose. The software reuse is a process in which the existing software is used to build new software. A metric is a quantitative indicator of an attribute of an item/thing. Reusability is the likelihood for a segment of source code that can be used again to add new functionalities with slight or no modification. A lot of research has been projected using reusability in reducing code, domain, requirements, design etc., but very little work is reported using software reuse in medical domain. An attempt is made to bridge the gap in this direction, using the concepts of clustering and classifying the data based on the distance measures. In this paper cardiologic database is considered for study. The developed model will be useful for Doctors or Para-medics to find out the patient’s level in the cardiologic disease, deduce the medicines required in seconds and propose them to the patient. In order to measure the reusability K-means clustering algorithm is used.
Inducing phase-locking and chaos in cellular oscillators by modulating the driving stimuli
Mogens H. Jensen,Sandeep Krishna
Quantitative Biology , 2011,
Abstract: Inflammatory responses in eucaryotic cells are often associated with oscillations in the nuclear-cytoplasmic translocation of the transcription factor NF-kB. In most laboratory realizations, the oscillations are triggered by a cytokine stimulus, like the tumor necrosis factor alpha, applied as a step change to a steady level. Here we use a mathematical model to show that an oscillatory external stimulus can synchronize the NF-kB oscillations into states where the ratios of the internal to external frequency are close to rational numbers. We predict a specific response diagram of the TNF-driven NF-kB system which exhibits bands of synchronization known as "Arnold tongues". Our model also suggests that when the amplitude of the external stimulus exceeds a certain threshold there is the possibility of coexistence of multiple different synchronized states and eventually chaotic dynamics of the nuclear NF-kB concentration. This could be used as a way of externally controlling immune response, DNA repair and apoptotic pathways.
Morpho-Physiological Characterization of Glyphosate-Resistant and -Susceptible Horseweed (Conyza canadensis) Biotypes of US Midsouth  [PDF]
Vijay K. Nandula, Daniel H. Poston, Clifford H. Koger, Krishna N. Reddy, K. Raja Reddy
American Journal of Plant Sciences (AJPS) , 2015, DOI: 10.4236/ajps.2015.61006
Abstract: Horseweed is traditionally considered a non-cropland weed. However, populations resistant to glyphosate have eventually become established in no-till agronomic cropping systems. Growth chamber and greenhouse experiments were conducted to compare selected biological and physiological parameters of glyphosate-resistant (GR) and -susceptible (GS) horseweed biotypes from Mississippi with a broader goal of fitness characterization in these biotypes. Vegetative growth parameters (number of leaves, rosette diameter and area, shoot and root fresh weights) were recorded weekly from 5 to 11 wk after emergence and reproductive attributes [days to bolting (production of a flowering stalk) and flowering] and senescence were measured for both GR and GS biotypes under high (24°C/20°C) and low (18°C/12°C) temperature regimes, both with a 13-h light period. Physiological traits such as net photosynthesis, phenolic content, and cell membrane thermostability, all in the presence and absence of glyphosate, and leaf content of divalent cations such as Ca2+ and Mg2+ were assayed in the two biotypes under the high temperature regime. All horseweed vegetative growth parameters except root fresh weight were higher in the high temperature regime compared to that in low temperature regime in both biotypes. Number of leaves, rosette diameter and area, shoot and root fresh weight were 40 vs. 35, 9.3 vs. 8.7 cm, 51 vs. 43 cm2, 3.7 vs. 3.2 g, and 3.5 vs. 4.2 g under high and low temperature conditions, respectively, when averaged across biotypes and weekly measurements. All growth parameters listed above were higher for the GR biotype compared to the GS biotype. Number of leaves, rosette diameter and area, shoot and root fresh weight were 38 vs. 37, 9.1 vs. 8.9 cm, 50.2 vs. 44 cm2, 3.9 vs. 3.1 g, and 4.3 vs. 3.5 g for GR and GS biotypes, respectively, averaged across the temperature treatments and weekly measurements. Reproductive developmental data of these biotypes indicated that the GS biotype bolted earlier than the GR biotype. The GS biotype had more phenolic content and exhibited higher cell membrane thermostability, but less net photosynthetic rate compared to the GR biotype. At 48 h after treatment with glyphosate, there was no change in phenolic content of both GR and GS biotypes. However, glyphosate reduced cell membrane thermostability and net photosynthetic rate more in the GS biotype than that in the GR biotype. Chemical analysis of GR and GS
Particle Swarm Optimized Optimal Threshold Value Selection for Clustering based on Correlation Fractal Dimension  [PDF]
Anuradha Yarlagadda, J. V. R. Murthy, M. H. M. Krishna Prasad
Applied Mathematics (AM) , 2014, DOI: 10.4236/am.2014.510155
Abstract:

The work on the paper is focused on the use of Fractal Dimension in clustering for evolving data streams. Recently Anuradha et al. proposed a new approach based on Relative Change in Fractal Dimension (RCFD) and damped window model for clustering evolving data streams. Through observations on the aforementioned referred paper, this paper reveals that the formation of quality cluster is heavily predominant on the suitable selection of threshold value. In the above-mentionedpaper Anuradha et al. have used a heuristic approach for fixing the threshold value. Although the outcome of the approach is acceptable, however, the approach is purely based on random selection and has no basis to claim the acceptability in general. In this paper a novel method is proposed to optimally compute threshold value using a population based randomized approach known as particle swarm optimization (PSO). Simulations are done on two huge data sets KDD Cup 1999 data set and the Forest Covertype data set and the results of the cluster quality are compared with the fixed approach. The comparison reveals that the chosen value of threshold by Anuradha et al., is robust and can be used with confidence.

Numerical Analysis of Stresses on Layer-by-Layer Basis in FML Composite Cylinder Subjected to External Hydrostatic Loading  [PDF]
B. G. Sumana, H. N. Vidya Sagar, K. V. Sharma, M. Krishna
Materials Sciences and Applications (MSA) , 2015, DOI: 10.4236/msa.2015.66052
Abstract: The aim of the research work was to numerically investigate the residual stresses induced between the layers of fiber metal laminate (FML) cylinder (glass/epoxy reinforced aluminum laminates) under buckling hydrostatic loading. For the analysis of buckling behavior of FML cylinders, various fiber orientations such as 0/90°, 60/30°, ±45° and ±55° and different FRP thickness of 1, 2, and 3 mm were considered. The aluminum cylinder of inner diameter 80 mm, length 800 mm and wall thickness 1 mm was modeled with SHELL281 element type and a total of 1033 elements were used for computing the induced residual stresses between the layers. The results show that magnitude of residual stresses between the layers decreased along the thickness from outer layer towards the inner layer in sine wave form. The maximum residual Von-Mises stress was at inner aluminum layer while the maximum residual radial stress was at the outermost layer of FML cylinder due to the inward pressure. Among all types of FML cylinder 0/90° fiber oriented FML cylinder exhibited the least radial stress and a maximum Von-Mises stress along the FRP thickness.
Stress-specific response of the p53-Mdm2 feedback loop
Alexander Hunziker, Mogens H Jensen, Sandeep Krishna
BMC Systems Biology , 2010, DOI: 10.1186/1752-0509-4-94
Abstract: We construct a mathematical model of the negative feedback loop involving p53 and its inhibitor, Mdm2, at the core of this pathway, and use it to examine the effect of different stresses that trigger p53. In response to DNA damage, hypoxia, etc., the model exhibits a wide variety of specific output behaviour - steady states with low or high levels of p53 and Mdm2, as well as spiky oscillations with low or high average p53 levels.We show that even a simple negative feedback loop is capable of exhibiting the kind of flexible stress-specific response observed in the p53 system. Further, our model provides a framework for predicting the differences in p53 response to different stresses and single nucleotide polymorphisms.The tumor suppressor protein, p53, is a transcription factor that regulates the activity of hundreds of genes involved in cell growth and death [1,2]. Over 50% of human cancer cells contain mutations in p53, because of which it has become a key target in cancer research [3]. A wide variety of stress conditions result in the accumulation and activation of p53 - among others: DNA damage, hypoxia, heat shock, nutrient deprivation and oncogene activation. Despite the fact that all these inputs are integrated into a single node, p53, the expression pattern of downstream genes (and hence the physiological response) appears to be specific to each stress. For example, hypoxia invariably leads to apoptosis [4], whereas ribonucleotide depletion leads to reversible cell cycle arrest [5], and UV irradiation can result in either cell cycle arrest or apoptosis depending on the intensity of the damage [6].How does the regulatory network around p53 retain this exibility even though all inputs converge at a single node? We argue in this paper that the particular design of the p53-Mdm2 feedback loop at the core of this network could be the source of this flexibility. p53 is regulated by other proteins at two levels: its stability (e.g., Pirh2, COP1, Mdm2 decrease its hal
STUDY OF DIMENSIONAL STABILITY, DECAY RESISTANCE, AND LIGHT STABILITY OF PHENYLISOTHIOCYANATE MODIFIED RUBBERWOOD
Krishna K. Pandey,Jayashree,H. C. Nagaveni
BioResources , 2009,
Abstract: Rubber wood (Hevea brasiliensis) was esterfied with phenylisothiocya-nate, and dimensional stability, decay resistance, and photo stability of the modified wood was assessed. The chemically modified wood was characterized by FTIR and CP/MAS 13C NMR spectroscopy. Unmodified and modified samples were exposed to a brown rot (Polyporus meliae) and a white rot (Coriolus versicolor) fungus for 12 weeks. Modified wood samples exhibited good dimensional stability and were very resistant to decay. However, phenylisothiocyanate modification of wood was not effective in decreasing photo-yellowing.
Thermodynamic approach to the dewetting instability in ultrathin films
N. Shirato,H. Krishna,R. Kalyanaraman
Physics , 2009, DOI: 10.1063/1.3456062
Abstract: The fluid dynamics of the classical dewetting instability in ultrathin films is a non-linear process. However, the physical manifestation of the instability in terms of characteristic length and time scales can be described by a linearized form of the initial conditions of the films's dynamics. Alternately, the thermodynamic approach based on equating the rate of free energy decrease to the viscous dissipation [de Gennes, C. R. Acad. Paris.v298, 1984] can give similar information. Here we have evaluated dewetting in the presence of thermocapillary forces arising from a film-thickness (h) dependent temperature. Such a situation can be found during pulsed laser melting of ultrathin metal films where nanoscale effects lead to a local h-dependent temperature. The thermodynamic approach provides an analytical description of this thermocapillary dewetting. The results of this approach agree with those from linear theory and experimental observations provided the minimum value of viscous dissipation is equated to the rate of free energy decrease. The flow boundary condition that produces this minimum viscous dissipation is when the film-substrate tangential stress is zero. The physical implication of this finding is that the spontaneous dewetting instability follows the path of minimum rate of energy loss.
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