Global visualization and quantification of compressible vortex loops

The physics of compressible vortex loops generated due to the rolling up of the shear layer upon the diffraction of a shock wave from a shock tube is far from being understood, especially when shock-vortex interactions are involved. This is mainly due to the lack of global quantitative data available which characterizes the flow. The present study involves the usage of the PIV technique to characterize the velocity and vorticity of compressible vortex loops formed at incident shock Mach numbers ofM=1.54 and1.66. Another perk of the PIV technique over purely qualitative methods, which has been demonstrated in the current study, is that at the same time the results also provide a clear image of the various flow features. Techniques such as schlieren and shadowgraph rely on density gradients present in the flow and fail to capture regions of the flow influenced by the primary flow structure which would have relatively lower pressure and density. Various vortex loops, namely, square, elliptic and circular, were generated using different shape adaptors fitted to the end of the shock tube. The formation of a coaxial vortex loop with opposite circulation along with the generation of a third stronger vortex loop ahead of the primary with same circulation direction are of the interesting findings of the current study

Optimized Neural Network Using Differential Evolutionary and Swarm Intelligence Optimization Algorithms for RF Power Prediction in Cognitive Radio Network: A Comparative study

Cognitive radio (CR) technology has emerged as a promising solution to many wireless communication problems including spectrum scarcity and underutilization. The a priory knowledge of Radio Frequency (RF) power (primary signals and/ or interfering signals plus noise) in the channels to be exploited by CR is of paramount importance. This will enable the selection of channel with less noise among idle (free) channels. Computational Intelligence (CI) techniques can be applied to these scenarios to predict the required RF power in the available channels to achieve optimum Quality of Service (QoS). In this paper, we developed a time domain based optimized Artificial Neural Network (ANN) model for the prediction of real world RF power within the GSM 900, Very High Frequency (VHF) and Ultra High Frequency (UHF) TV bands. The application of the models produced was found to increase the robustness of CR applications, specifically where the CR had no prior knowledge of the RF power related parameters such as signal to noise ratio, bandwidth and bit error rate. The models used, implemented a novel and innovative initial weight optimization of the ANN’s through the use of differential evolutionary and swarm intelligence algorithms. This was found to enhance the accuracy and generalization of the ANN model. For this problem, DE/best/1/bin was found to yield a better performance as compared with the other algorithms implemented

Optimized Artificial Neural Network Using Differential Evolution for Prediction of RF Power in VHF/UHF TV and GSM 900 Bands for Cognitive Radio Networks

Cognitive radio (CR) technology has emerged as a promising solution to many wireless communication problems including spectrum scarcity and underutilization. The knowledge of Radio Frequency (RF) power (primary signals and/ or interfering signals plus noise) in the channels to be exploited by CR is of paramount importance, not just the existence or absence of primary users. If a channel is known to be noisy, even in the absence of primary users, using such channels will demand large quantities of radio resources (transmission power, bandwidth, etc) in order to deliver an acceptable quality of service to users. Computational Intelligence (CI) techniques can be applied to these scenarios to predict the required RF power in the available channels to achieve optimum Quality of Service (QoS). While most of the prediction schemes are based on the determination of spectrum holes, those designed for power prediction use known radio parameters such as signal to noise ratio (SNR), bandwidth, and bit error rate. Some of these parameters may not be available or known to cognitive users. In this paper, we developed a time domain based optimized Artificial Neural Network (ANN) model for the prediction of real world RF power within the GSM 900, Very High Frequency (VHF) and Ultra High Frequency (UHF) TV bands. The application of the models produced was found to increase the robustness of CR applications, specifically where the CR had no prior knowledge of the RF power related parameters. The models used implemented a novel and innovative initial weight optimization of the ANN’s through the use of differential evolutionary algorithms. This was found to enhance the accuracy and generalization of the approac

East African origins for Madagascan chickens as indicated by mitochondrial DNA

Published 22 March 2017The colonization of Madagascar by Austronesian-speaking people during AD 50–500 represents the most westerly point of the greatest diaspora in prehistory. A range of economically important plants and animals may have accompanied the Austronesians. Domestic chickens (Gallus gallus) are found in Madagascar, but it is unclear how they arrived there. Did they accompany the initial Austronesian-speaking populations that reached Madagascar via the Indian Ocean or were they late arrivals with Arabian and African sea-farers? To address this question, we investigated the mitochondrial DNA control region diversity of modern chickens sampled from around the Indian Ocean rim (Southeast Asia, South Asia, the Arabian Peninsula, East Africa and Madagascar). In contrast to the linguistic and human genetic evidence indicating dual African and Southeast Asian ancestry of the Malagasy people, we find that chickens in Madagascar only share a common ancestor with East Africa, which together are genetically closer to South Asian chickens than to those in Southeast Asia. This suggests that the earliest expansion of Austronesian-speaking people across the Indian Ocean did not successfully introduce chickens to Madagascar. Our results further demonstrate the complexity of the translocation history of introduced domesticates in Madagascar.Michael B. Herrera, Vicki A. Thomson, Jessica J.Wadley, Philip J. Piper, Sri Sulandari, Anik Budhi Dharmayanthi, Spiridoula Kraitsek, Jaime Gongora and Jeremy J. Austi

Dynamic transcription programs during ES cell differentiation towards mesoderm in serum versus serum-freeBMP4 culture

Expression profiling of embryonic stem (ES) cell differentiation in the presence of serum has been performed previously. It remains unclear if transcriptional activation is dependent on complext growth factor mixtures in serum or whether this process is intrinsic to ES cells once the stem cell program has been inactivated. The aims of this study were to determine the transcriptional programs associated with the stem cell state and to characterize mesoderm differentiation between serum and serum-free culture

A culture-independent method for studying transfer of IncI1 plasmids from wild-type Escherichia coli in complex microbial communities

IncI1 plasmids play a central role in the transfer of antimicrobial resistance genes among Enterobacteriaceae in animals and humans. Knowledge on the dynamics of IncI1 plasmid transfer is limited, mainly due to lack of culture-independent methods that can quantify donor strain survival and plasmid transfer in complex microbial communities. The aim of this study was to develop a culture-independent method to study the dynamics of IncI1 plasmids transfer by fluorescence-activated cell sorting. We genetically modified three wild-type Escherichia coli of animal (n = 2) and human (n = 1) origin carrying blaCMY-2 or blaCTX-M-1 on two epidemic IncI1 plasmids (pST12 and pST7). Non-coding regions on the chromosome and on the IncI1 plasmid of each strain were tagged with mCherry (red) and GFPmut3 (green) fluorescent proteins, respectively, using lambda recombineering. A gene cassette expressing mCherry and lacIq was inserted into the chromosome, whereas the plasmid was marked with a GFPmut3 cassette with LacIq repressible promoter. Therefore, gfpmut3 was repressed in donor strains but expressed in recipient strains acquiring the plasmids. We demonstrated that genetic engineering of the strains did not affect the growth rate and plasmid transfer-ability in filter and broth matings. A proof-of-concept experiment using the CoMiniGut, an in vitro model of the colon, proved the validity of our method for studying the survival of wild-type E. coli and horizontal transfer of IncI1 plasmids under different pH and oxygen conditions. The dual-labeling method by fluorescent proteins is useful to determine persistence of exogenous E. coli and transfer dynamics of IncI1 plasmids in microbial communities

Specific interaction of methionine adenosyltransferase with free radicals

Although free radicals have been traditionally implicated in cell injury, and associated to pathophysiological processes, recent data implicate them in cell signaling events. Free radicals are naturally occurring oxygen-,nitrogen-and sulfur-derived species with an unpaired electron, such as superoxide, hydroxyl radical or nitric oxide. In order to assess the role of free radicals in cell signaling, we have studies the modulator effect of oxygen and nitrogen active species on liver methionine adenosyltransferase (MAT), a key metabolic enzyme. The presence of 10 cysteine residues per subunit, makes liver MAT a sensitive target for oxidation/nitrosylation. Here we show that purified MAT from rat liver is nitrosylated and oxidized in vitro. Incubation with H202 or the NO donor S-nitrosylated GSH (GSNO), diminish MAT activity in a dose-and time-dependent manner. Furthermore, the inactivation derived from both oxidation and nitrosylation, was reverted by GSH. MAT inactivation originates on the specific and covalent modification of the sulphydryl group of cysteine residue 121. We also studied how free radicals modulate MAT activity in vivo. It was previously shown that MAT activity is strongly dependent on cellular GSH levels. Generation of oxygen and nitrogen active species in rats by injection of LPS, induced a decrease of liver MAT activity. This effect might derive from nitrosylation and/or oxidation of the enzyme. Modulation of liver MAT by NO is further supported by the inactivation of this enzyme observed in experimental models in which NO is produced; such as the administration of NO donors to rats and in hepatocytes cultured in hypoxia, a condition that induces the expression of the inducible nitric oxide synthase (iNOS). Oxidation also controls liver MAT activity in a cell environment as shown in CHO cells stably transfected with rat liver MAT cDNA upon addition of H2O2 to the culture medium. This effect depends upon the generation of the hydroxyl radical. On the basis of the metabolic implications of liver MAT, together with the structural features accounting for the sensitivity of this enzyme to active oxygen and nitrogen species, we propose that modulation of MAT by these agents could be a mechanism to regulate the consumption of ATP in the liver, and thus preserve cellular viability under different stress conditions

Adaptive-mutation compact genetic algorithm for dynamic environments

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link

Spectrum Occupancy Survey in Leicester, UK, For Cognitive Radio Application

Cognitive radio (CR) technology has emerged as a promising solution to many wireless communication problems including spectrum scarcity and underutilization. Knowing the current state of spectrum utilization in frequency, time and spatial domain will enhance the implementation of CR network. In this paper, we evaluate the spectrum utilization of some selected bands in Leicester city, UK; based on long time spectrum measurements using energy detection method. This study provides evidence of gross underutilization of some licenses spectrum which can be exploited by CR for efficient spectrum utilization