On the incorporation of cubic and hexagonal interfacial energy anisotropy in phase field models using higher order tensor terms

In this paper, we show how to incorporate cubic and hexagonal anisotropies in interfacial energies in phase field models; this incorporation is achieved by including upto sixth rank tensor terms in the free energy expansion, assuming that the free energy is only a function of coarse grained composition, its gradient, curvature and aberration. We derive the number of non-zero and independent components of these tensors. Further, by demanding that the resultant interfacial energy is positive definite for inclusion of each of the tensor terms individually, we identify the constraints imposed on the independent components of these tensors. The existing results in the invariant group theory literature can be used to simplify the process of construction of some (but not all) of the higher order tensors. Finally, we derive the relevant phase field evolution equations.Comment: About 14 pages; 2 figures, to be submitted for revie

Effect of Epitaxial Strain on Phase Separation in Thin Films

We examine the role of an imposed epitaxial strain e in enhancing or depressing the spinodal instability of an alloy thin film. Since the alloy film starts with an imposed strain, phase separation offers a mechanism to relieve it, but only when the film is elastically inhomogeneous. With composition-dependence of elastic modulus given by y, and that of lattice parameter by {\eta}, our simulations using the Cahn-Hilliard model show (and analytical results for early stages confirm) that, for (ey/{\eta}) > 0, the imposed strain adds to the driving force for phase separation, decreases the maximally growing wave length, and expands the coherent spinodal in the phase diagram. Further, when (ey/{\eta}) > 0.372, it expands to even outside of chemical spinodal. Phase separation produces islands of elastically softer (harder) phase with (without) a favorable imposed strain. These results are in agreement with experimental results in GeSi thin films on Si and Ge substrates, as well as in InGaAs films on GaAs substrates.Comment: 4 pages, 3 figure

Pregnancy associated plasma protein-A (PAPP-A) as an early marker for the diagnosis of acute coronary syndrome.

Aims and objectives Pregnancy associated plasma protein-A (PAPP-A), a metalloproteinase plays a pivotal role in the pathogenesis of atherosclerosis. Recent studies have reported that elevated levels of PAPP-A, signal the onset of acute coronary syndrome (ACS). We, therefore, proposed to study the analytical competence of PAPP-A in patients admitted to the emergency department with chest pain and finally diagnosed as ACS. Methods and results Pregnancy associated plasma protein-A was measured using enzyme-linked immunosorbent assay (ELISA) in 485 patients admitted to emergency care unit, of which 89 patients were diagnosed as Non-cardiac chest pain (NCCP). Elevated levels of PAPP-A were observed in patients diagnosed as ACS on comparison with the controls. Receiver operator characteristic (ROC) curve analysis showed PAPP-A to be a good discriminator between ischaemic and non-ischaemic patients. The area under the curve was found to be 0.904, 95% CI (0.874–0.929) with 90% sensitivity and 85% specificity (P< 0.0001). The cut-off value from the ROC curve was 0.55 μg/mL above which PAPP-A was considered to be positive. Conclusion Pregnancy associated plasma protein-A seems to be a promising biomarker for identification and risk stratification for patients with ACS

Feeding back and enhancing authentic learning in quality course assessment design : locating information systems education in rigorous educational research

Locating information systems education foursquare within rigorous and substantial educational research is crucial if the discipline is to receive the scholarly attention that it warrants. One way to do that is to highlight how current information systems course design in Australian undergraduate and postgraduate programs exhibits the strongest possible elements of contemporary learning theories. This paper analyses selected features of the design of an information systems postgraduate course in an Australian university, including the use of peer review of journal entries and writing professional reports to enhance authentic learning and maximise quality assessment design. The analysis is framed by the principles of instructional design theory (Snyder 2009). The authors argue that, by demonstrating theoretically grounded and effective educational practice, the course highlights the value of being located in wider educational research, and of bringing the two fields more closely together.<br /