Spectral method for the unsteady incompressible Navier-Stokes equations in gauge formulation

A spectral method which uses a gauge method, as opposed to a projection method, to decouple the computation of velocity and pressure in the unsteady incompressible Navier-Stokes equations, is presented. Gauge methods decompose velocity into the sum of an auxilary field and the gradient of a gauge variable, which may, in principle, be assigned arbitrary boundary conditions, thus overcoming the issue of artificial pressure boundary conditions in projection methods. A lid-driven cavity flow is used as a test problem. A subtraction method is used to reduce the pollution effect of singularities at the top corners of the cavity. A Chebyshev spectral collocation method is used to discretize spatially. An exponential time differencing method is used to discretize temporally. Matrix diagonalization procedures are used to compute solutions directly and efficiently. Numerical results for the flow at Reynolds number Re = 1000 are presented, and compared to benchmark results. It is shown that the method, called the spectral gauge method, is straightforward to implement, and yields accurate solutions if Neumann boundary conditions are imposed on the gauge variable, but suffers from reduced convergence rates if Dirichlet boundary conditions are imposed on the gauge variable

Conformal Maps to Multiply-Slit Domains and Applications

By exploiting conformal maps to vertically slit regions in the complex plane, a recently developed rational spectral method [Tee and Trefethen, 2006] is able to solve PDEs with interior layer-like behaviour using significantly fewer collocation points than traditional spectral methods. The conformal maps are chosen to 'enlarge the region of analyticity' in the solution: an idea which can be extended to other numerical methods based upon global polynomial interpolation. Here we show how such maps can be rapidly computed in both periodic and nonperiodic geometries, and apply them to some challenging differential equations

A rational spectral collocation method with adaptively transformed Chebyshev grid points

A spectral collocation method based on rational interpolants and adaptive grid points is presented. The rational interpolants approximate analytic functions with exponential accuracy by using prescribed barycentric weights and transformed Chebyshev points. The locations of the grid points are adapted to singularities of the underlying solution, and the locations of these singularities are approximated by the locations of poles of Chebyshev-Padé approximants. Numerical experiments on two time-dependent problems, one with finite time blow-up and one with a moving front, indicate that the method far outperforms the standard Chebyshev spectral collocation method for problems whose solutions have singularities in the complex plan close to [-1,1]

Prognostic value of serum levels of immunoglobulins (IgG, IgA, IgM and IgE) in breast cancer: a preliminary study.

One hundred and sixty women admitted for breast tumour biopsy to the King's College Hospital group have been followed sequentially for 2 years. Sixty-nine women had early operable breast cancer and 91 had benign breast disease. All these women had serum immunoglobulin IgG, IgA, IgM and IgE levels measured preoperatively and postoperatively at 3 months, 1 year and 2 years. No differences were found in any of the serum immunoglobulin levels between the two groups at any time. There was, however, a positive correlation between the extent of metastatic breast cancer and the serum level of various immunoglobulins, particularly IgA. There was no evidence that routine postoperative radiotherapy influenced the levels of serum immunoglobulins. The findings suggest a secondary defence reaction against increasing tumour load, and do not support the theory of an early immune defect in immunoglobulin metabolism which could play a part in the pathogenesis of breast cancer. Although there is no diagnostic value in measuring the levels of serum immunoglobulins in patients with breast tumours, there may be some value in following the levels in cancer patients, as a guide to subclinical spread of the disease

Analysis of quorum-sensing Pantoea stewartii strain M073a through whole-genome sequencing

YesPantoea stewartii strain M073a is a Gram-negative bacterium isolated from a tropical waterfall. This strain exhibits quorum-sensing activity. Here, the assembly and annotation of its genome are presented.High Impact Research Grants from the University of Malaya (UM.C/625/1/HIR/MOHE/CHAN/01, grant no. A-000001-50001 and UM-MOHE HIR Grant UM.C/625/1/HIR/MOHE/ CHAN/14/1, no. H-50001-A000027

Pandoraea sp. strain E26: discovery of its quorum-sensing properties via whole-genome sequence analysis

YesWe report the draft genome sequence of Pandoraea sp. strain E26 isolated from a former landfill site, sequenced by the Illumina MiSeq platform. This genome sequence will be useful to further understand the quorum-sensing system of this isolate.University of Malaya High-Impact Research (HIR) grants (UM C/625/1/HIR/MOHE/CHAN/01, grant A-000001- 50001 and UM-MOHE HIR UM C/625/1/HIR/MOHE/CHAN/14/1, grant H-50001-A000027

Successful fault current interruption on DC circuit breaker

This study focus on the interruption capability of the DC circuit breaker employing a current commutation approach and evaluates the two main factors that determine the success rate for breaker current interruption, namely the current slope di/dt before current zero and the rate of rise of the transient recovery voltage dv/dt across the mechanical breaker contacts after current zero. A vacuum circuit breaker is used to evaluate DC breaker characteristics. Detailed mathematical and graphical analysis are presented for the proposed circuit operation used in analysing the circuit breaker properties, with simulation and experimental results at fault current levels up to 330 A

Draft genome sequence of Aeromonas caviae strain L12, a quorum-sensing strain isolated from a freshwater lake in Malaysia

YesHere, we present the draft genome sequence of Aeromonas caviae strain L12, which shows quorum-sensing activity. The availability of this genome sequence is important to the research of the quorum-sensing regulatory system in this isolate.High Impact Research Grants from the University of Malaya (A000001-50001; UM-MOHE HIR Grant UM C/625/1/HIR/MOHE/CHAN/14/1, H-50001-A000027

Whole-genome analysis of quorum-sensing Burkholderia sp. strain A9

YesBurkholderia spp. rely on N-acyl homoserine lactone as quorum-sensing signal molecules which coordinate their phenotype at the population level. In this work, we present the whole genome of Burkholderia sp. strain A9, which enables the discovery of its N-acyl homoserine lactone synthase gene.UM High Impact Research Grants (UM-MOHE HIR grant UM C/625/1/HIR/MOHE/CHAN/01, H-50001-A000001 and UMMOHE HIR Grant UM C/625/1/HIR/MOHE/CHAN/14/1, H-50001- A000027

Food waste handling in Malaysia and comparison with other Asian countries

The increasing amount of food waste in Malaysia in recent years has brought many environmental issues in the country where it affects the nation’s solid waste management framework. At the moment, the government is limited to other alternatives of food waste disposal besides the conventional landfill and incineration methods. This paper provides information on the current status of food waste handling, management, regulations, and policies in Malaysia. It helps to draw the problem and challenge to a clearer view in efforts of achieving sustainable and integrative food waste handling in the country