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Search Results: 1 - 10 of 225915 matches for " Krishna R Veeramah "
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Little genetic differentiation as assessed by uniparental markers in the presence of substantial language variation in peoples of the Cross River region of Nigeria
Krishna R Veeramah, Bruce A Connell, Naser Pour, Adam Powell, Christopher A Plaster, David Zeitlyn, Nancy R Mendell, Michael E Weale, Neil Bradman, Mark G Thomas
BMC Evolutionary Biology , 2010, DOI: 10.1186/1471-2148-10-92
Abstract: The Cross River region was shown to be extremely homogenous for both Y-chromosome and mtDNA markers with language spoken having no noticeable effect on the genetic structure of the region, consistent with estimates of inter-language gene flow of 10% per generation based on sociological data. However the groups in the region could clearly be differentiated from others in Cameroon and Ghana (and to a lesser extent Igbo populations). Significant correlations between genetic distance and both geographic and linguistic distance were observed at this larger scale.Previous studies have found significant correlations between genetic variation and language in Africa over large geographic distances, often across language families. However the broad sampling strategies of these datasets have limited their utility for understanding the relationship within language families. This is the first study to show that at very fine geographic/linguistic scales language differences can be maintained in the presence of substantial gene flow over an extended period of time and demonstrates the value of dense sampling strategies and having DNA of known and detailed provenance, a practice that is generally rare when investigating sub-Saharan African demographic processes using genetic data.The Cross River region (named after the river of the same name that passes through it) is situated in the extreme southeast of Nigeria, with its headwaters in the adjacent parts of Cameroon. The land to the north east of the Cross River region (Figure 1) is now generally accepted as the approximate location from which the expansion of the Bantu-speaking peoples began between three and five thousand years ago [1-3]. Bantu languages are now spoken throughout most of sub-Saharan Africa south of the equator. The Cross River region was also a major source of slaves during the Atlantic slave trade with Calabar, at the confluence of the Cross and Calabar Rivers, becoming both the region's principal urban centre a
Population-genetic comparison of the Sorbian isolate population in Germany with the German KORA population using genome-wide SNP arrays
Arnd Gross, Anke T?njes, Peter Kovacs, Krishna R Veeramah, Peter Ahnert, Nab R Roshyara, Christian Gieger, Ina-Maria Rueckert, Markus Loeffler, Mark Stoneking, Heinz-Erich Wichmann, John Novembre, Michael Stumvoll, Markus Scholz
BMC Genetics , 2011, DOI: 10.1186/1471-2156-12-67
Abstract: The degree of relatedness was significantly higher in the Sorbs. Principal components analysis revealed a west to east clustering of KORA individuals born in Germany, KORA individuals born in Poland or Czech Republic, Half-Sorbs (less than four Sorbian grandparents) and Full-Sorbs. The Sorbs cluster is nearest to the cluster of KORA individuals born in Poland. The number of rare SNPs is significantly higher in the Sorbs sample. FST between KORA and Sorbs is an order of magnitude higher than between different regions in Germany. Compared to the other populations, Sorbs show a higher proportion of individuals with runs of homozygosity between 2.5 Mb and 5 Mb. Linkage disequilibrium (LD) at longer range is also slightly increased but this has no effect on the power of association studies.Oversampling of families in the Sorbs sample causes detectable bias regarding higher FST values and higher LD but the effect is an order of magnitude smaller than the observed differences between KORA and Sorbs. Relatedness in the Sorbs also influenced the power of uncorrected association analyses.Sorbs show signs of genetic isolation which cannot be explained by over-sampling of relatives, but the effects are moderate in size. The Slavonic origin of the Sorbs is still genetically detectable.Regarding LD structure, a clear advantage for genome-wide association studies cannot be deduced. The significant amount of cryptic relatedness in the Sorbs sample results in inflated variances of Beta-estimators which should be considered in genetic association analyses.The Sorbs living in the Upper Lusatia region of Eastern Saxony are one of the few historic ethnic minorities in Germany. They are of Slavonic origin speaking a west Slavic language (Sorbian), and it is assumed that they have lived in ethnic isolation among the German majority during the past 1100 years [1]. Therefore, this population may be of special interest for genetic studies of complex traits.The value of isolated populations f
Strong selective sweeps associated with ampliconic regions in great ape X chromosomes
Kiwoong Nam,Kasper Munch,Asger Hobolth,Julien Y. Dutheil,Krishna Veeramah,August Woerner,Michael F. Hammer,Great Ape Genome Diversity Project,Thomas Mailund,Mikkel H. Schierup
Quantitative Biology , 2014,
Abstract: The unique inheritance pattern of X chromosomes makes them preferential targets of adaptive evolution. We here investigate natural selection on the X chromosome in all species of great apes. We find that diversity is more strongly reduced around genes on the X compared with autosomes, and that a higher proportion of substitutions results from positive selection. Strikingly, the X exhibits several megabase long regions where diversity is reduced more than five fold. These regions overlap significantly among species, and have a higher singleton proportion, population differentiation, and nonsynonymous to synonymous substitution ratio. We rule out background selection and soft selective sweeps as explanations for these observations, and conclude that several strong selective sweeps have occurred independently in similar regions in several species. Since these regions are strongly associated with ampliconic sequences we propose that intra-genomic conflict between the X and the Y chromosomes is a major driver of X chromosome evolution.
Efficacy of a single dose of a transdermal diclofenac patch as pre-emptive postoperative analgesia: a comparison with intramuscular diclofenac
R Krishna
Southern African Journal of Anaesthesia and Analgesia , 2012,
Abstract: Background: We compared the analgesic efficacy of a transdermal diclofenac patch 100 mg (NuPatch 100, Zydus Cadila, Ahmedabad, India) and intramuscular diclofenac sodium 75 mg (Voveran , Novartis, India) for postoperative analgesia, and the associated side-effects of the transdermal diclofenac patch. Method: Sixty participants in the study were randomly allocated to two groups of 30 each, by a computer-generated randomisation table. The anaesthetic procedure was standardised. A transdermal diclofenac patch 100 mg was applied to the participants in the study group at the beginning of the surgery. In the control group, 75 mg of diclofenac sodium was given intramuscularly half an hour before the end of surgery. Pain was assessed postoperatively at two-, six-, and 12-hour intervals using a visual analogue scale (VAS). An injection of tramadol 2 mg/kg was administered intramuscularly as rescue analgesia. The study ended when the patients asked for rescue analgesia, or when the VAS score was > 5. Results: The mean duration of analgesia in the control group was 7 hours 28 minutes, and in study group, it was 8 hours 6 minutes, which was comparable (p-value < 0.341). Conclusion: Intraoperative application of a single dose of 100 mg transdermal diclofenac patch is as effective as a single dose of intramuscular diclofenac (75 mg) for acute postoperative pain, without any significant side-effects.
The scorpion envenoming syndrome: a different perspective. The physiological basis of the role of insulin in scorpion envenoming
Journal of Venomous Animals and Toxins , 2000, DOI: 10.1590/S0104-79302000000100002
Abstract: death caused by scorpion envenoming (buthidae family) is a common event in tropical and subtropical countries. severe scorpion envenoming causes an autonomic storm resulting in a massive release of catecholamines, angiotensin ii, glucagon, cortisol, and changes in insulin secretion. as a consequence of these changes in the hormonal milieu, scorpion envenoming results in a syndrome of fuel energy deficits and an inability of the vital organs to utilize the existing metabolic substrates, which causes myocardial damage, cardiovascular disturbances, peripheral circulatory failure, pulmonary oedema, and many other clinical manifestations alone or in combination, producing multi-system-organ-failure (msof) and death. insulin-glucose infusion or antivenom administration through the release of insulin seems to be the physiological basis for the control of the metabolic response when that has become a determinant to survival of scorpion sting victims.
Selection and testing of ballast stones for underground railway tracks
MW Chanda, R Krishna
African Journal of Science and Technology , 2003,
Abstract: Ballast is broken pieces of hard rocks such as sandstones, schist, etc. approximately 25- 60 mm size, over which the railway tracks are laid. The function of the ballast is to transfer the applied load over a large surface, provide adequate elasticity, prevent creep and hold the sleepers in position. Also under wet conditions, it would permit free drainage and allow free grade to be obtained. It is reported that a large proportion of serious accidents occur through derailments of carriages. Many such accidents may be due to the poor quality of ballast stones. The paper discusses the essential properties of ballast stones and methodologies for testing these properties. African Journal of Science and Technology Vol.4(2) 2003: 42-50
Comprehensive study on perceived barriers to low vision services
Ilango K,Krishna R
Indian Journal of Ophthalmology , 2005,
Simulation of Spread and Control of Lesions in Brain
T. R. Krishna Mohan
Physics , 2007,
Abstract: A simulation model for the spread and control of lesions in the brain is constructed using a planar network (graph) representation for the Central Nervous System (CNS). The model is inspired by the lesion structures observed in the case of Multiple Sclerosis (MS), a chronic disease of the CNS. The initial lesion site is at the center of a unit square and spreads outwards based on the success rate in damaging edges (axons) of the network. The damaged edges send out alarm signals which, at appropriate intensity levels, generate programmed cell death. Depending on the extent and timing of the programmed cell death, the lesion may get controlled or aggravated akin to the control of wild fires by burning of peripheral vegetation. The parameter phase space of the model shows smooth transition from uncontrolled situation to controlled situation. The simulations show that the model is capable of generating a wide variety of lesion growth and arrest scenarios.
Time Series Modeling of River Flow Using Wavelet Neural Networks  [PDF]
B. Krishna, Y. R. Satyaji Rao, P. C. Nayak
Journal of Water Resource and Protection (JWARP) , 2011, DOI: 10.4236/jwarp.2011.31006
Abstract: A new hybrid model which combines wavelets and Artificial Neural Network (ANN) called wavelet neural network (WNN) model was proposed in the current study and applied for time series modeling of river flow. The time series of daily river flow of the Malaprabha River basin (Karnataka state, India) were analyzed by the WNN model. The observed time series are decomposed into sub-series using discrete wavelet transform and then appropriate sub-series is used as inputs to the neural network for forecasting hydrological variables. The hybrid model (WNN) was compared with the standard ANN and AR models. The WNN model was able to provide a good fit with the observed data, especially the peak values during the testing period. The benchmark results from WNN model applications showed that the hybrid model produced better results in estimating the hydrograph properties than the latter models (ANN and AR).
Estimation of Global Solar Radiation for Four Selected Sites in Nepal Using Sunshine Hours, Temperature and Relative Humidity  [PDF]
Krishna R. Adhikari, Binod K. Bhattarai, Shekhar Gurung
Journal of Power and Energy Engineering (JPEE) , 2013, DOI: 10.4236/jpee.2013.13003
Abstract: Rational and accurate solar energy databases, essential for designing, sizing and performing the solar energy systems in any part of the world, are not easily accessible in different localities of Nepal. In this study, daily global solar radiation, sunshine hours and meteorological data for Biratnagar, Kathmandu, Pokhara and Jumla have been used to derive the regression constants. The linear regression technique has been used to develop a model for Biratnagar, Kathmandu, Pokhara and Jumla. The model has calculated the global solar radiation for these locations. The values of global solar radiation estimated by the model are found to be in close agreement with measured values of respective sites. The estimated values were compared with Angstrom-Prescott model and examined using the root mean square error (RMSE), mean bias error (MBE), mean percentage error (MPE), coefficient of regression (R), coefficient of determinant (R2) and correlation coefficient (CC) statistical techniques. Thus, the resultant correlations and linear regression relations may be then used for the locations of similar meteorological/geographical characteristics and also can be used to estimate the missing data of solar radiation for the respective site.
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