70 research outputs found

    A Note On 3Solitary Wave Solutions of the Compound Burgers-Korteweg-de Vries Equation"

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    The goal of this note is to construct a class of traveling solitary wave solutions for the compound Burgers-Korteweg-de Vries equation by means of a hyperbolic ansatz

    Optimum control of cavity flow

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    For high Reynolds numbers Re = UL/nu, with an order of magnitude of a few thousands, a flow over a square cavity becomes unsteady with the growth of two-dimensional instabilities. This phenomenon is studied by computing : 1/ the branch of steady solutions with respects to the Reynolds number, using a branch tracking method ; 2/ the eigenvalues and eigenvectors of the global linearized operator with respects to Re. We thus show that the cavity is subject to a Hopf bifurcation at a critical Reynolds number denoted by Rec. After setting the computations in a supercritical case for which Re > Rec, we use an optimum control algorithm to minimize the energy of the perturbations at various terminal times T. The control will consist in unsteady blowing and succion on the cavity wall. We will analyze the phenomenology of the control law with a description of the influence of the target time T and the cost of the control which will be denoted by m

    The blending effect of natural polysaccharides with nano-zirconia towards the removal of fluoride and arsenate from water

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    Nano-zirconia (ZO) was synthesized using a microwave-assisted one-pot precipitation route. Two biopolymers, chitosan (CTS) and carboxymethyl cellulose were blended with ZO at different w/w ratios. The formulation with 30% w/w chitosan (ZO-CTS) was found to give enhanced uptake of F− and As(V). ZO and the most effective ZO-CTS system were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. These confirmed the formation of a composite system containing nanoparticles of 50 nm in size, in which ZO was present in the amorphous form. It was observed that the combination of ZO with CTS improved the F− and As(V) adsorption capacity most notably at pH 5.5. Fluoride adsorption by ZO-CTS followed the Freundlich isotherm model, with an adsorption capacity of 120 mg g−1. Adsorption of As(V) by ZO-CTS could be fitted with both the Langmuir and Freundlich isotherm models and was found to have a capacity of 14.8 mg g−1. Gravity filtration studies conducted for groundwater levels indicated the effectiveness of ZO-CTS in adsorbing As(V) and F− at a pH of 5.5. The ability of the ZO-CTS in removing Cd(II) and Pb(II) was also investigated, and no such enhancement was observed, and found the neat ZO was the most potent sorbent here

    The genotypes and virulence attributes of C. albicans isolates from oral leukoplakia

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    There is a debate as to whether some types of oral leucoplakias (OL) are caused by Candida species, and whether they contribute to the malignant transformation, associated with a minority of such lesions. As no detailed population analysis of yeast isolates from OL is available, we evaluated the virulence attributes, and genotypes of 35 C. albicans from OL, and compared their genotypes with 18 oral isolates from healthy individuals. The virulence traits evaluated were esterase, phospholipase, proteinase, haemolysin and coagulase production, and phenotypic switching activity, and yeast adherence and biofilm formation. DNA from OL and control yeasts were evaluated for A, B or C genotype status. Phospholipase, proteinase, and coagulase activity and biofilm formation was observed in 80%, 66%, 97 % and 77 % of the isolates, respectively. Phenotypic switching was detected in 8.6%, while heamolytic, and esterase activity and adherence were noted in all isolates. The genotype A was predominant amongst both the OL and control groups. Due to the small sample size of our study a larger investigation to define the role of candidal virulent attributes in the pathogenicity of OL is warranted, and the current data should serve as a basis until then

    Resequencing Candidate Genes Implicates Rare Variants in Asthma Susceptibility

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    Common variation in over 100 genes has been implicated in the risk of developing asthma, but the contribution of rare variants to asthma susceptibility remains largely unexplored. We selected nine genes that showed the strongest signatures of weak purifying selection from among 53 candidate asthma-associated genes, and we sequenced the coding exons and flanking noncoding regions in 450 asthmatic cases and 515 nonasthmatic controls. We observed an overall excess of p values <0.05 (p = 0.02), and rare variants in four genes (AGT, DPP10, IKBKAP, and IL12RB1) contributed to asthma susceptibility among African Americans. Rare variants in IL12RB1 were also associated with asthma susceptibility among European Americans, despite the fact that the majority of rare variants in IL12RB1 were specific to either one of the populations. The combined evidence of association with rare noncoding variants in IL12RB1 remained significant (p = 3.7 × 10−4) after correcting for multiple testing. Overall, the contribution of rare variants to asthma susceptibility was predominantly due to noncoding variants in sequences flanking the exons, although nonsynonymous rare variants in DPP10 and in IL12RB1 were associated with asthma in African Americans and European Americans, respectively. This study provides evidence that rare variants contribute to asthma susceptibility. Additional studies are required for testing whether prioritizing genes for resequencing on the basis of signatures of purifying selection is an efficient means of identifying novel rare variants that contribute to complex disease

    Large-scale genome-wide association studies and meta-analyses of longitudinal change in adult lung function.

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    BACKGROUND: Genome-wide association studies (GWAS) have identified numerous loci influencing cross-sectional lung function, but less is known about genes influencing longitudinal change in lung function. METHODS: We performed GWAS of the rate of change in forced expiratory volume in the first second (FEV1) in 14 longitudinal, population-based cohort studies comprising 27,249 adults of European ancestry using linear mixed effects model and combined cohort-specific results using fixed effect meta-analysis to identify novel genetic loci associated with longitudinal change in lung function. Gene expression analyses were subsequently performed for identified genetic loci. As a secondary aim, we estimated the mean rate of decline in FEV1 by smoking pattern, irrespective of genotypes, across these 14 studies using meta-analysis. RESULTS: The overall meta-analysis produced suggestive evidence for association at the novel IL16/STARD5/TMC3 locus on chromosome 15 (P  =  5.71 × 10(-7)). In addition, meta-analysis using the five cohorts with ≥3 FEV1 measurements per participant identified the novel ME3 locus on chromosome 11 (P  =  2.18 × 10(-8)) at genome-wide significance. Neither locus was associated with FEV1 decline in two additional cohort studies. We confirmed gene expression of IL16, STARD5, and ME3 in multiple lung tissues. Publicly available microarray data confirmed differential expression of all three genes in lung samples from COPD patients compared with controls. Irrespective of genotypes, the combined estimate for FEV1 decline was 26.9, 29.2 and 35.7 mL/year in never, former, and persistent smokers, respectively. CONCLUSIONS: In this large-scale GWAS, we identified two novel genetic loci in association with the rate of change in FEV1 that harbor candidate genes with biologically plausible functional links to lung function

    Meta-analysis of genome-wide association studies of asthma in ethnically diverse North American populations.

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    Asthma is a common disease with a complex risk architecture including both genetic and environmental factors. We performed a meta-analysis of North American genome-wide association studies of asthma in 5,416 individuals with asthma (cases) including individuals of European American, African American or African Caribbean, and Latino ancestry, with replication in an additional 12,649 individuals from the same ethnic groups. We identified five susceptibility loci. Four were at previously reported loci on 17q21, near IL1RL1, TSLP and IL33, but we report for the first time, to our knowledge, that these loci are associated with asthma risk in three ethnic groups. In addition, we identified a new asthma susceptibility locus at PYHIN1, with the association being specific to individuals of African descent (P = 3.9 × 10(-9)). These results suggest that some asthma susceptibility loci are robust to differences in ancestry when sufficiently large samples sizes are investigated, and that ancestry-specific associations also contribute to the complex genetic architecture of asthma

    Managing Soil and Plant Nutrients: Role of Microbial Phosphate Solubilisation

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    Phosphorus (P) is one of the macronutrients required for the optimum growth and development of plants. The deficiency of P can be compensated by adding chemical fertilisers, which are expensive and have a negative impact on the ecosystem. Solubilisation of phosphate by microorganisms is an emerging application for eco-friendly and sustainable agriculture practices. This chapter discuss the importance of P for plants, the main problems related to the over-exploitation of natural reserves of P and chemical fertilisers, the diversity of phosphate-solubilising microorganisms (PSM), the ability of microorganisms to solubilise phosphates and key mechanisms of microbial P solubilisation, the capability of microorganisms to formulate phosphate-related nanoparticles, the potential of PSM to develop as commercial level biofertiliser and contribution of PSM for achieving Sustainable Development Goals (SDGs). This chapter will highlight the input of PSM in sustainable agriculture

    African-specific alleles modify risk for asthma at the 17q12-q21 locus in African Americans

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    BACKGROUND: Asthma is the most common chronic disease in children, occurring at higher frequencies and with more severe disease in children with African ancestry. METHODS: We tested for association with haplotypes at the most replicated and significant childhood-onset asthma locus at 17q12-q21 and asthma in European American and African American children. Following this, we used whole-genome sequencing data from 1060 African American and 100 European American individuals to identify novel variants on a high-risk African American-specific haplotype. We characterized these variants in silico using gene expression and ATAC-seq data from airway epithelial cells, functional annotations from ENCODE, and promoter capture (pc)Hi-C maps in airway epithelial cells. Candidate causal variants were then assessed for correlation with asthma-associated phenotypes in African American children and adults. RESULTS: Our studies revealed nine novel African-specific common variants, enriched on a high-risk asthma haplotype, which regulated the expression of GSDMA in airway epithelial cells and were associated with features of severe asthma. Using ENCODE annotations, ATAC-seq, and pcHi-C, we narrowed the associations to two candidate causal variants that are associated with features of T2 low severe asthma. CONCLUSIONS: Previously unknown genetic variation at the 17q12-21 childhood-onset asthma locus contributes to asthma severity in individuals with African ancestries. We suggest that many other population-specific variants that have not been discovered in GWAS contribute to the genetic risk for asthma and other common diseases