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Search Results: 1 - 10 of 461954 matches for " A. Jayaraman "
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Clusters of CDK2, CCND1, and CMYC genes involved in cancers: Acute Lymphocytic Leukemia (ALL) as a model
A Jayaraman
Biology and Medicine , 2012,
Abstract: Cancer is not a single disease but it involves changes in multifunctional genes, the causes for these changes remain less understood. It is now becoming clear that multiple genes orchestrate to turn on the carcinogenesis process. These genes involve several signaling pathways which then characterize uncontrolled cell divisions. Our aim was to study cell cycle genes CDK2, CCND1, and c-MYC to determine their clustering in the evolutionary pathway and to understand their diversions leading to continued cell division processes. Since Acute Lymphoblastic Leukemia (ALL)is the most prevalent form of cancer in children we took this as a model for analyzing the role of these genes in theleukemia process. The prevalence/spread of these genes was found to be very limited in the animal kingdom; hencethe question is whether this may be due to the fact that during evolution in time there could have been loss of some functions or mutations in these genes which relates to the switch function of these genes. Alternatively, have they evolved in a way which we are unable to trace due to limited methodology? Further, with the results analyzed so far we can imagine that these species in which we found the presence of these genes across the animal kingdom could have had cancer like diseases during their lifetime. We conclude that each of these genes formed several clusters which were typical of their role/functions in ALL.
The interaction of p53 and MDM2 genes in cancers, in silico studies and phylogenetic analysis
A. Jayaraman
Biology and Medicine , 2011,
Abstract: The normal cell cycle process is a crucial process and is generally mediated by a number of regulatory genes. One ofthe most important regulators is the tumor suppressor p53, which in turn is regulated by MDM2 gene. The expressionof p53 and MDM2 is found to be frequently altered in many cancers and metastasis/ relapses .This is the first reportto look at the evolutionary history of these genes to decipher the role of these genes in the tumorigenesis processusing in silico methods. We also found that they showed high degree of sequence similarity across the mammalianspecies, indicating that these species probably share parallel cancer causing mechanisms. Their individual unrootedphylogenetic tree formed 5 clusters each; however, p53 gene was found in a large number of species whereasMDM2 was found in smaller number of species. The role of MDM2 is therefore limited and occurs in fewer speciesacross the mammalian species. It is evident that these molecules play an important role in the cancer process,perhaps responsible for relapses and hence need to be explored further as therapeutic targets. Such studies that arebased on evidence from paleontology and genetics suggest that mechanisms of cancer are embedded deeplythroughout evolution. Understanding the phylogenetic evolution of these genes could help in furthering our knowledgeon the mechanisms involved in cancer.
Absorbing aerosols: contribution of biomass burning and implications for radiative forcing
H. Gadhavi ,A. Jayaraman
Annales Geophysicae (ANGEO) , 2010,
Abstract: Absorbing aerosols supplements the global warming caused by greenhouse gases. However, unlike greenhouse gases, the effect of absorbing aerosol on climate is not known with certainty owing to paucity of data. Also, uncertainty exists in quantifying the contributing factors whether it is biomass or fossil fuel burning. Based on the observations of absorption coefficient at seven wavelengths and aerosol optical depth (AOD) at five wavelengths carried out at Gadanki (13.5° N, 79.2° E), a remote village in peninsular India, from April to November 2008, as part of the "Study of Atmospheric Forcing and Responses (SAFAR)" pilot campaign we discuss seasonal variation of black carbon (BC) concentration and aerosol optical depth. Also, using spectral information we estimate the fraction of fossil-fuel and non-fossil fuel contributions to absorption coefficient and contributions of soot (Black Carbon), non-soot fine mode aerosols and coarse mode aerosols to AOD. BC concentration is found to be around 1000 ng/m3 during monsoon months (JJAS) and around 4000 ng/m3 during pre and post monsoon months. Non-fossil fuel sources contribute nearly 20% to absorption coefficient at 880 nm, which increases to 40% during morning and evening hours. Average AOD is found to be 0.38±0.15, with high values in May and low in September. Soot contributes nearly 10% to the AOD. This information is further used to estimate the clear sky aerosol direct radiative forcing. Top of the atmosphere aerosol radiative forcing varies between 4 to 0 W m 2, except for April when the forcing is positive. Surface level radiative forcing is between 10 to 20 W m 2. The net radiation absorbed within the atmosphere is in the range of 9 to 25 W m 2, of which soot contributes about 80 to 90%.
Airborne lidar study of the vertical distribution of aerosols over Hyderabad, an urban site in central India, and its implication for radiative forcing calculations
H. Gadhavi ,A. Jayaraman
Annales Geophysicae (ANGEO) , 2006,
Abstract: Use of a compact, low power commercial lidar onboard a small aircraft for aerosol studies is demonstrated. A Micro Pulse Lidar fitted upside down in a Beech Superking aircraft is used to measure the vertical distribution of aerosols in and around Hyderabad, an urban location in the central India. Two sorties were made, one on 17 February 2004 evening hours and the other on 18 February 2004 morning hours for a total flight duration of four hours. Three different algorithms, proposed by Klett (1985), Stephens et al. (2001) and Palm et al. (2002) for deriving the aerosol extinction coefficient profile from lidar data are studied and is shown that the results obtained from the three methods compare within 2%. The result obtained from the airborne lidar is shown more useful to study the aerosol distribution in the free troposphere than that obtained by using the same lidar from ground. Using standard radiative transfer model the aerosol radiative forcing is calculated and is shown that knowledge on the vertical distribution of aerosols is very important to get more realistic values than using model vertical profiles of aerosols. We show that for the same aerosol optical depth, single scattering albedo and asymmetry parameter but for different vertical profiles of aerosol extinction the computed forcing values differ with increasing altitude and improper selection of the vertical profile can even flip the sign of the forcing at tropopause level.
On the role of dust storms in triggering atmospheric gravity waves observed in the middle atmosphere
S. K. Das, A. Taori,A. Jayaraman
Annales Geophysicae (ANGEO) , 2011,
Abstract: Lower atmospheric perturbations often produce measurable effects in the middle and upper atmosphere. The present study demonstrates the response of the middle atmospheric thermal structure to the significant enhancement of the lower atmospheric heating effect caused by dust storms observed over the Thar Desert, India. Our study from multi-satellite observations of two dust storm events that occurred on 3 and 8 May 2007 suggests that dust storm events produce substantial changes in the lower atmospheric temperatures as hot spots which can become sources for gravity waves observed in the middle atmosphere.
Fog-induced variations in aerosol optical and physical properties over the Indo-Gangetic Basin and impact to aerosol radiative forcing
S. K. Das, A. Jayaraman,A. Misra
Annales Geophysicae (ANGEO) , 2008,
Abstract: A detailed study on the changes in aerosol physical and optical properties during fog events were made in December 2004 at Hissar (29.13° N, 75.70° E), a city located in the Indo-Gangetic basin. The visible aerosol optical depth was relatively low (0.3) during the initial days, which, however, increased (0.86) as the month progressed. The increasing aerosol amount, the decreasing surface temperature and a higher relative humidity condition were found favoring the formation of fog. The fog event is also found to alter the aerosol size distribution. An increase in the number concentration of the nucleation mode (radius<0.1 μm) particles, along with a decrease in the mode radius showed the formation of freshly nucleated aerosols. In the case of accumulation mode (0.1 μm
Glutamate receptors as seen by light: spectroscopic studies of structure-function relationships
Mankiewicz, K.A.;Jayaraman, V.;
Brazilian Journal of Medical and Biological Research , 2007, DOI: 10.1590/S0100-879X2007001100001
Abstract: ionotropic glutamate receptors are major excitatory receptors in the central nervous system and also have a far reaching influence in other areas of the body. their modular nature has allowed for the isolation of the ligand-binding domain and for subsequent structural studies using a variety of spectroscopic techniques. this review will discuss the role of specific ligand:protein interactions in mediating activation in the a-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid subtype of glutamate receptors as established by various spectroscopic investigations of the glur2 and glur4 subunits of this receptor. specifically, this review will provide an introduction to the insight gained from x-ray crystallography and nuclear magnetic resonance investigations and then go on to focus on studies utilizing vibrational spectroscopy and fluorescence resonance energy transfer to study the behavior of the isolated ligand-binding domain in solution and discuss the importance of specific ligand:protein interactions in the mechanism of receptor activation.
Carbamate pesticide induced toxic epidermal necrolysis
Rajendran N,Chitfambalam P,Jayaraman A
Indian Journal of Dermatology, Venereology and Leprology , 2001,
Abstract: A 36-year-old male alleged to have consumed carbamate pesticide liquid (Baygon@) developed toxic epidermal necrolysis (TEN) within twenty-four hours of intake. Though drugs have been commonly incriminated as offending agents for TEN, carbamate pesticide was found to be the causative agent in our case.
Naphthenic Acid Corrosion in Petroleum Refineries. A Review La corrosion naphténique en raffinerie. Synthèse bibliographique
Jayaraman A.,Singh H.,Lefebvre Y.
Oil & Gas Science and Technology , 2006, DOI: 10.2516/ogst:1986016
Abstract: The problem of naphthenic acid corrosion is specific to certain crudes from India, Romania, Russia, Texas, Venezuela, Congo, Nigeria, etc. The nature of corrosion due to naphthenic acids is in the form of sharp-edged streamlined grooves. Detailed laboratory studies and some field data indicate that naphthenic acid corrosion increases beyond a specific neutralization number of crude, when the process temperature is between 220 and 400°C and when fluid velocities are high. The different factors responsible for naphthenic corrosion as well as the ways of fighting it are reviewed. Among them are predistillation, the blending of crudes, neutralization, the selection of construction materials and especially the mastery of fluid flow. La corrosion naphténique est spécifique à certains bruts de l'Inde, de la Roumanie, de l'URSS, du Texas, du Venezuela, du Congo, du Nigeria, etc. L'aspect de la corrosion due aux acides naphténiques est caractéristique, cratères et sillons à arètes vives. Des études de laboratoire et surtout l'expérience en raffinerie montrent que la corrosion naphténique, au-dessus d'un indice d'acide spécifique et dans un domaine de température de l'ordre de 220 à 400°C, cro t avec la vitesse des fluides. Les différents facteurs responsables de la corrosion naphténique ainsi que les moyens de la combattre sont passés en revue. Parmi eux, la prédistillation, le mélange de bruts, la neutralisation, la sélection des matériaux de construction et surtout la ma trise de l'écoulement des fluides.
Synthesis, Structural and Dielectric Properties of Ferroelectric Dichloridoglycine Zinc Dihydrate Single Crystals  [PDF]
S. Suresh, A. Ramanand, D. Jayaraman, S.M. Priya, R. Vasanthakumari
Journal of Minerals and Materials Characterization and Engineering (JMMCE) , 2011, DOI: 10.4236/jmmce.2011.104024
Abstract: The strong electro mechanical coupling exhibited by the ferroelectric materials is the remarkable feature of these materials. Therefore, they find applications in sensors, actuators for producing ultrasonics and micro positioning. The material dichloridoglycine zinc dihydrate is a centrosymmetric ferroelectric crystal. In the present study, this crystal has been grown from a mixture of glycine and zinc chloride. The dielectric constant and the dielectric loss of the grown crystal were studied as a function of frequency and temperature, and the corresponding relaxation time (τ), relaxation frequency (Fr) and the activation energy have been calculated. The ferroelectric property of the crystal has been confirmed by dielectric studies. The ferroelectric characteristics of the crystal have been studied and reported.
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