27 research outputs found

    Detecting Discontinuities Over Triangular Meshes Using Multiwavelets

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    It is well known that solutions to nonlinear hyperbolic PDEs develop discontinuities in time. The generation of spurious oscillations in such regions can be prevented by applying a limiter in the troubled zones. In earlier work, we constructed a multiwavelet troubled-cell indicator for one and (tensor-product) two dimensions (SIAM J. Sci. Comput. 38(1):A84–A104, 2016). In this paper, we investigate multiwavelet troubled-cell indicators on structured triangular meshes. One indicator uses a problem-dependent parameter; the other indicator is combined with outlier detection

    Invasive aspergillosis by aspergillus flavus: Epidemiology, diagnosis, antifungal resistance, and management

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    Aspergillus flavus is the second most common etiological agent of invasive aspergillosis (IA) after A. fumigatus. However, most literature describes IA in relation to A. fumigatus or together with other Aspergillus species. Certain differences exist in IA caused by A. flavus and A. fumigatus and studies on A. flavus infections are increasing. Hence, we performed a comprehensive updated review on IA due to A. flavus. A. flavus is the cause of a broad spectrum of human diseases predominantly in Asia, the Middle East, and Africa possibly due to its ability to survive better in hot and arid climatic conditions compared to other Aspergillus spp. Worldwide, ~10% of cases of bronchopulmonary aspergillosis are caused by A. flavus. Outbreaks have usually been associated with construction activities as invasive pulmonary aspergillosis in immunocompromised patients and cutaneous, subcutaneous, and mucosal forms in immunocompetent individuals. Multilocus microsatellite typing is well standardized to differentiate A. flavus isolates into different clades. A. flavus is intrinsically resistant to polyenes. In contrast to A. fumigatus, triazole resistance infrequently occurs in A. flavus and is associated with mutations in the cyp51C gene. Overexpression of efflux pumps in non-wildtyp

    Influence of Stefan blowing on nanofluid flow submerged in microorganisms with leading edge accretion or ablation

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    The unsteady forced convective boundary layer flow of viscous incompressible fluid containing both nanoparticles and gyrotactic microorganisms, from a flat surface with leading edge accretion (or ablation), is investigated theoretically. Utilizing appropriate similarity transformations for the velocity, temperature, nanoparticle volume fraction and motile microorganism density, the governing conservation equations are rendered into a system of coupled, nonlinear, similarity ordinary differential equations. These equations, subjected to imposed boundary conditions, are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order numerical method in the MAPLE symbolic software. Good agreement between our computations and previous solutions is achieved. The effect of selected parameters on flow velocity, temperature, nano-particle volume fraction (concentration) and motile microorganism density function is investigated. Furthermore, tabular solutions are included for skin friction, wall heat transfer rate, nano-particle mass transfer rate and microorganism transfer rate. Applications of the study arise in advanced micro-flow devices to assess nanoparticle toxicity

    Evaluation of the interface-capturing algorithm of OpenFoam for the simulation of incompressible immiscible two-phase flow

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    The Mass-Conserving Level-Set method combines the efficiency of a Level-Set algorithm with the mass conserving properties of the Volume Of Fluid method. It avoids the work intensive interface construction of the former method and imposes a mass-conserving correction to the distance function of the latter. The interface capturing algorithm implemented in OpenFOAM uses a compressive convection scheme for the evolution of the VOF colour function, as opposed to an interface reconstruction algorithm. Therefore, it can be assumed to match the efficiency of the MCLS method. Further analysis of the accuracy of the algorithm is required to make a fair comparison. In this report the accuracy will be evaluated for the simulation of incompressible, immiscible two-phase flow in two and three spatial dimensions. Three representative test cases are considered: The advection of a spherical bubble for an imposed, constant velocity field (2D), a rising (buoyant) bubble in a quiescent fluid (2D and 3D) and a stationary bubble in a stationary fluid (2D and 3D). The computed results are compared with results obtained with the Mass-Conserving Level-Set method of [8], benchmark results of [5] and other references. The compressive scheme accurately conserves mass, but shows large spurious currents for the test cases with surface tension. Additionally, the error in the predicted rise velocity of the gas bubble is large in comparison with that of the MCLS method.Electrical Engineering, Mathematics and Computer Scienc

    Phytochemical investigation and antimicrobial activity of Derris scandens

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    Different fractions of root and stem of Derris scandens demonstrated good antibacterial (Escherichia coli, and Bacillus megaterium), antialgal (Chlorella fusca), and antifungal (Microbotryum violaceum) activities. Phytochemical investigation resulted in isolation of scandenin, scandenin A, betulinic acid, lupeol, β-amyran-3-one, β-amyrin, β-sitosterol and ß-sitosterol glucopyranoside. Study showed that scandenin has strong antibacterial activity against B. megaterium and good antifungal and antialgal properties. Scandenin A showed good antibacterial, antifungal and antialgal properties

    Capacity Building in Pediatric Critical Care-Global Health Research and Education: The Blantyre Experience

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    Pediatric critical care medicine (PCCM), as it is practiced in high-income countries, is focused on specialized medical care for the most vulnerable pediatric patient populations. However, best practices for provision of that care globally are lacking. Thus, PCCM research and education programming can potentially fill significant knowledge gaps by facilitating the development of evidence-based clinical guidelines that reduce child mortality on a global scale. Malaria remains a leading cause of pediatric mortality worldwide. The Blantyre Malaria Project (BMP) is a research and clinical care collaborative that has focused on reducing the public health burden of pediatric cerebral malaria in Malawi since 1986. In 2017, the requirements of a new research study led to the creation of PCCM services in Blantyre, creating the opportunity to establish a PCCM-Global Health Research Fellowship by BMP in collaboration with the University of Maryland School of Medicine. In this perspective piece, we reflect on the evolution of the PCCM-Global Health research fellowship. Although the specifics of this fellowship are out of the scope of this perspective, we discuss the context allowing for the development of this program and explore some early lessons learned to consider for future capacity-building efforts in the future of PCCM-Global Health research
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