An efficient implementation of an implicit FEM scheme for fractional-in-space reaction-diffusion equations

Fractional differential equations are becoming increasingly used as a modelling tool for processes with anomalous diffusion or spatial heterogeneity. However, the presence of a fractional differential operator causes memory (time fractional) or nonlocality (space fractional) issues, which impose a number of computational constraints. In this paper we develop efficient, scalable techniques for solving fractional-in-space reaction diffusion equations using the finite element method on both structured and unstructured grids, and robust techniques for computing the fractional power of a matrix times a vector. Our approach is show-cased by solving the fractional Fisher and fractional Allen-Cahn reaction-diffusion equations in two and three spatial dimensions, and analysing the speed of the travelling wave and size of the interface in terms of the fractional power of the underlying Laplacian operator

Annular honeycomb seals: Test results for leakage and rotordynamic coefficients; comparisons to labyrinth and smooth configurations

Test results are presented for leakage and rotordynamic coefficients for seven honeycomb seals. All seals have the same radius, length, and clearance; however, the cell depths and diameters are varied. Rotordynamic data, which are presented, consist of the direct and cross-coupled stiffness coefficients and the direct damping coefficients. The rotordynamic-coefficient data show a considerable sensitivity to changes in cell dimensions; however, no clear trends are identifiable. Comparisons of test data for the honeycomb seals with labyrinth and smooth annular seals show the honeycomb seal had the best sealing (minimum leakage) performance, followed in order by the labyrinth and smooth seals. For prerotated fluid entering the seal, in the direction of shaft rotation, the honeycomb seal has the best rotordynamic stability followed in order by the labyrinth and smooth. For no prerotation, or fluid prerotation against shaft rotation, the labyrinth seal has the best rotordynamic stability followed in order by the smooth and honeycomb seals

Ten Years in Rehabilitation of Spoil: Appearance, Plant Colonists, and the Dominant Herbivore

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Improving Data Quality in Conversion Projects: The Impact of Source Systems and Team Experience

Poor data quality has been shown to have a serious impact on organization performance including increased operational cost and ineffective decision-making. In response to poor data, many organizations take on data cleansing projects as part of ERP and data warehouse implementations. These projects can be extremely difficult and produce less than desired results. This study will examine the data cleanup efforts taken on by an organization specializing in implementing and maintaining benefits modules for an ERP system. In particular this study will build on research in traditional software development and examine the impact of the conversion and cleansing team’s experience with the source systems, the target system and systems within a similar domain on the accuracy of data following the conversion and cleanup effort

The multifunctional NS1 protein of influenza A viruses

The non-structural (NS1) protein of influenza A viruses is a non-essential virulence factor that has multiple accessory functions during viral infection. In recent years, the major role ascribed to NS1 has been its inhibition of host immune responses, especially the limitation of both interferon (IFN) production and the antiviral effects of IFN-induced proteins, such as dsRNA-dependent protein kinase R (PKR) and 2'5'-oligoadenylate synthetase (OAS)/RNase L. However, it is clear that NS1 also acts directly to modulate other important aspects of the virus replication cycle, including viral RNA replication, viral protein synthesis, and general host-cell physiology. Here, we review the current literature on this remarkably multifunctional viral protein. In the first part of this article, we summarize the basic biochemistry of NS1, in particular its synthesis, structure, and intracellular localization. We then discuss the various roles NS1 has in regulating viral replication mechanisms, host innate/adaptive immune responses, and cellular signalling pathways. We focus on the NS1-RNA and NS1-protein interactions that are fundamental to these processes, and highlight apparent strain-specific ways in which different NS1 proteins may act. In this regard, the contributions of certain NS1 functions to the pathogenicity of human and animal influenza A viruses are also discussed. Finally, we outline practical applications that future studies on NS1 may lead to, including the rational design and manufacture of influenza vaccines, the development of novel antiviral drugs, and the use of oncolytic influenza A viruses as potential anti-cancer agents.Publisher PDFPeer reviewe

Deriving Business Value from Asymmetric Penalty-Reward Perspectives of IS users

When features are added to an existing IS product in response to market demands it is important to assess their business value before implementing them into the product. But how does one estimate the true value of a new feature? Is it sufficient to consider only the customer reward for including a feature into the product or is it also useful to evaluate the customer penalty for not building the feature into the product? The current methods for feature selection capture only the customer inputs for building. The implications of not building the feature are not captured. This study investigates the adequacy of such an approach and discovers that additional business information can be derived by considering both, the reward as well as the penalty perspective of the customer. This information can be utilized by IS developers in adopting the right strategy for product enhancement

Social Traps of Agile methods

Social traps are situations within which individuals or groups face the prospect of adopting seemingly beneficial behaviors that have negative consequences over time or for a larger collective (Platt, 1973). While on the one hand, the Agile manifesto has been welcomed by many in the software developer community who often perceived formal processes as management generated inefficiency that gets in the way of productivity (Anderson, 2005). On the other hand proponents of formal plan-driven approaches argue that in spite of the lofty ideals and claims made, Agile development only postpone costs for the developing organization. Following the threads of this debate through a review of extant literature this conceptual study suggests that there is a real risk of developers using Agile methods falling into social trap\u27 of compromising the long-term goals for short-term gains