Spectral stability of noncharacteristic isentropic Navier-Stokes boundary layers

Building on work of Barker, Humpherys, Lafitte, Rudd, and Zumbrun in the shock wave case, we study stability of compressive, or "shock-like", boundary layers of the isentropic compressible Navier-Stokes equations with gamma-law pressure by a combination of asymptotic ODE estimates and numerical Evans function computations. Our results indicate stability for gamma in the interval [1, 3] for all compressive boundary-layers, independent of amplitude, save for inflow layers in the characteristic limit (not treated). Expansive inflow boundary-layers have been shown to be stable for all amplitudes by Matsumura and Nishihara using energy estimates. Besides the parameter of amplitude appearing in the shock case, the boundary-layer case features an additional parameter measuring displacement of the background profile, which greatly complicates the resulting case structure. Moreover, inflow boundary layers turn out to have quite delicate stability in both large-displacement and large-amplitude limits, necessitating the additional use of a mod-two stability index studied earlier by Serre and Zumbrun in order to decide stability

Gaussians versus back-to-back exponentials: a numerical study

The underlying magnetic field distribution in many samples studied by the mu R technique is asymmetric. Despite this, quite often fit functions assuming symmetric (Gaussian) distributions are used. Here, a back-to-back exponential function, which can be made asymmetric with fit parameters, is studied numerically alongside a Gaussian function to see how well each fits symmetric and asymmetric simulated data. Both fit symmetric data well, but the back-to-back exponential is found to be superior for fitting asymmetric data

Effects of Solution, Soil and Sand Cultures on Nodulation and Growth of Phasey Bean

Plants of phasey bean (Macroptilium lathyroides cv. Murray) were grown in nitrogen-free nutrient solution, sod, or sand culture in a naturally-Nt glasshouse. Nodulation, dry matter accumulation in plant parts, and seed yields were assessed. Partitioning of symbiotic nitrogen into various plant parts during vegetative and reproductive growth stages was also determined. In all culture media, nodule number and size increased with plant age but the rate of increase was generally greater in solution than in the other cultures. In sand culture, the dry weight per nodule and per plant, and plant growth were significantly suppressed. Although tap root elongation was consistently better in solution than soil or sand culture, leaf development and dry matter accumulation in roots and stems were enhanced by solution culture only during flowering and fruiting stage. Seed yields were significantly increased by solution culture, an effect apparently associated with increased symbiotic nitrogen fixation. During vegetative growth, nitrogen accumulated largely in the leaves and stems but pods were major sinks of nitrogen during the reproductive growth stage. The benefits and applications of solution culture in the study of nodule development and collection of root samples for acetylene reduction assays are discussed

What's new in surface irrigation equipment

Advances are being made to improve and develop new equipment for both furrow and flooding methods of surface irrigation

Existence and stability of viscoelastic shock profiles

We investigate existence and stability of viscoelastic shock profiles for a class of planar models including the incompressible shear case studied by Antman and Malek-Madani. We establish that the resulting equations fall into the class of symmetrizable hyperbolic--parabolic systems, hence spectral stability implies linearized and nonlinear stability with sharp rates of decay. The new contributions are treatment of the compressible case, formulation of a rigorous nonlinear stability theory, including verification of stability of small-amplitude Lax shocks, and the systematic incorporation in our investigations of numerical Evans function computations determining stability of large-amplitude and or nonclassical type shock profiles.Comment: 43 pages, 12 figure

Intelligent Financial Fraud Detection Practices: An Investigation

Financial fraud is an issue with far reaching consequences in the finance industry, government, corporate sectors, and for ordinary consumers. Increasing dependence on new technologies such as cloud and mobile computing in recent years has compounded the problem. Traditional methods of detection involve extensive use of auditing, where a trained individual manually observes reports or transactions in an attempt to discover fraudulent behaviour. This method is not only time consuming, expensive and inaccurate, but in the age of big data it is also impractical. Not surprisingly, financial institutions have turned to automated processes using statistical and computational methods. This paper presents a comprehensive investigation on financial fraud detection practices using such data mining methods, with a particular focus on computational intelligence-based techniques. Classification of the practices based on key aspects such as detection algorithm used, fraud type investigated, and success rate have been covered. Issues and challenges associated with the current practices and potential future direction of research have also been identified.Comment: Proceedings of the 10th International Conference on Security and Privacy in Communication Networks (SecureComm 2014

In Deadly Time: The Lasting On of Waste in Mayhew’s London

This paper examines the temporal dimension of waste in Henry Mayhew’s London Labour and the London Poor as an instance of how modernity has produced a largely hidden domain of the non-identical and indeterminate. Through a consideration of the phenomena of uselessness, decay and poverty I argue that the temporal dimension of waste is constituted as a corrosive or malign ‘Deadly Time.’ In placing such emphasis on time directed towards death, I aim to show that Mayhew’s undisciplined researches can be seen as a valuable source for understanding why modern thinking struggles to come to terms with waste

Geometric phase in the Hopf bundle and the stability of non-linear waves

We develop a stability index for the traveling waves of non-linear reaction–diffusion equations using the geometric phase induced on the Hopf bundle . This can be viewed as an alternative formulation of the winding number calculation of the Evans function, whose zeros correspond to the eigenvalues of the linearization of reaction–diffusion operators about the wave. The stability of a traveling wave can be determined by the existence of eigenvalues of positive real part for the linear operator. Our for locating and counting eigenvalues is inspired by the numerical results in Way’s Way (2009). We provide a detailed proof of the relationship between the phase and eigenvalues for dynamical systems defined on and sketch the proof of the method of geometric phase for and its generalization to boundary-value problems. Implementing the numerical method, modified from Way (2009), we conclude with open questions inspired from the results

Transmission of mitochondrial DNA following assisted reproduction and nuclear transfer

Review of the articleMitochondria are the organelles responsible for producing the majority of a cell's ATP and also play an essential role in gamete maturation and embryo development. ATP production within the mitochondria is dependent on proteins encoded by both the nuclear and the mitochondrial genomes, therefore co-ordination between the two genomes is vital for cell survival. To assist with this co-ordination, cells normally contain only one type of mitochondrial DNA (mtDNA) termed homoplasmy. Occasionally, however, two or more types of mtDNA are present termed heteroplasmy. This can result from a combination of mutant and wild-type mtDNA molecules or from a combination of wild-type mtDNA variants. As heteroplasmy can result in mitochondrial disease, various mechanisms exist in the natural fertilization process to ensure the maternal-only transmission of mtDNA and the maintenance of homoplasmy in future generations. However, there is now an increasing use of invasive oocyte reconstruction protocols, which tend to bypass mechanisms for the maintenance of homoplasmy, potentially resulting in the transmission of either form of mtDNA heteroplasmy. Indeed, heteroplasmy caused by combinations of wild-type variants has been reported following cytoplasmic transfer (CT) in the human and following nuclear transfer (NT) in various animal species. Other techniques, such as germinal vesicle transfer and pronuclei transfer, have been proposed as methods of preventing transmission of mitochondrial diseases to future generations. However, resulting embryos and offspring may contain mtDNA heteroplasmy, which itself could result in mitochondrial disease. It is therefore essential that uniparental transmission of mtDNA is ensured before these techniques are used therapeutically