A comparison between MMAE and SCEM for solving singularly perturbed linear boundary layer problems

In this study, we propose an efficient method so-called Successive Complementary Expansion Method (SCEM), that is based on generalized asymptotic expansions, for approximating to the solutions of singularly perturbed two-point boundary value problems. In this easy-applicable method, in contrast to the well-known method the Method of Matched Asymptotic Expansions (MMAE), any matching process is not required to obtain uniformly valid approximations. The key point: A uniformly valid approximation is adopted first, and complementary functions are obtained imposing the corresponding boundary conditions. An illustrative and two numerical experiments are provided to show the implementation and numerical properties of the present method. Furthermore, MMAE results are also obtained in order to compare the numerical robustnesses of the methods.No sponso

Molecular Mechanisms Underlying Stress-Induced GLIA Remodeling in the Nematode C. Elegans

Animals can adapt to long-term environmental changes by modifying their behavior, which can be accompanied by structural alterations of the nervous system. Such alterations are common in sensory organs, composed of sensory neurons and glia, which initially detect environmental stress. The molecular mechanisms driving cell shape remodeling following environmental stress and the effects of such remodeling on animal survival are not well understood. C. elegans is an excellent model in which to study neuronal and glial cell remodeling. Under normal growth conditions, the sensory receptive endings of the bilateral AWC sensory neurons, which respond to volatile odorants, are individually ensheathed by processes of adjacent amphid sheath (AMsh) glial cells. Upon exposure to high temperature, starvation, or crowding, animals enter an alternative developmental state, called dauer, in which bilateral AMsh glia membranes surrounding the AWC neuron fuse, connecting the two glial cells, and allowing the AWC neuronal receptive endings to expand. Previous studies from our lab identified several AMsh glia proteins required for remodeling. These include (1) the cell fusion protein AFF-1, (2) a VEGFR-related protein VER-1, (3) the Otd/Otx transcription factor TTX-1, and (4) the zinc-finger transcription factor ZTF-16. ver-1 expression in AMsh glia is induced by dauer entry or by cultivation Ph.D. at high temperature, and requires direct binding of TTX-1 to ver-1 regulatory sequences. To identify additional genes involved in stress-induced sensory organ remodeling, we performed a forward genetic screen, seeking mutants in which ver-1 expression at high temperature is not induced. One mutant recovered from this screen harbors a causal lesion in F47D2.11 gene, which encodes a 7- transmembrane G-protein coupled receptor (GPCR). Mutations in F47D2.11 not only block ver-1 induction, but also prevent dauer-induced AMsh glia remodeling and result in a delay in exit from the dauer state following exposure to a favorable environment. F47D2.11 mutants can be rescued by expression of the wild-type cDNA in AMsh glia but not in AWC neurons. These results implicate F47D2.11 in the sensation of dauer conditions in AMsh glia, required for dauer-induced glial remodeling and timely dauer exit

The proposed alignment framework in enterprise architecture development for the Omani public sector

The misalignment between Enterprise Architecture (EA) development and stakeholders’ goals plays a vital role in the low acceptance of EA in organizations and governments. Literature has highlighted the need for an alignment framework to support enterprise architects to align the development process of EA with the stakeholders’ goals. Hence, this research developed an alignment framework to align the EA development process with the stakeholders to produce an agreed architecture that supports the architects. Multiple Perspectives Theory (MPT) was used to develop a preliminary research model that provided the initial guidance in data collection and analysis. The research employed a qualitative case study approach to build an in-depth understanding of EA development process, enterprise architects and stakeholders’ roles, as well as the factors influencing the alignment between them. The Government Architecture Framework (GAF) of the Omani public sector was used as the case study that included GAF documentation review, and interviews with architects and stakeholders who participated in the development of GAF. The findings showed that twelve alignment factors influenced the development of GAF which are standardization, development scope, principles, governance, top management support, culture, commitment, awareness, communication, value of EA, change management capability and experience. These factors were used as the base to develop the alignment framework followed by a focus group session with GAF architects was organized to validate the final framework. As a conclusion, the study has shown that the alignment framework provides a comprehensive understanding for practitioners and academicians about the factors and their influences at each EA development step