Web-based systems design: a study of contemporary practices and an explanatory framework based on “method-in-action”

This paper reports the findings of a detailed study of Web-based systems design (WBSD) practices in Ireland based on data collected over a 3-year period (2002–2005), the objectives of which were to (1) contribute towards a richer understanding of the current “real-world” context of WBSD by characterising the profile of a typical project (team size, timeframe, nature of requirements, etc.) and identifying the key challenges, constraints, and imperatives (i.e. “mediating factors”) faced by Web-based system designers, and (2) understand how those contextual parameters and mediating factors influence the activity of WBSD as regards the selection and enactment of whatever design practices are therefore engaged (i.e. the use of methods, procedures, etc.). Data was gathered through a survey which yielded 165 usable responses, and later through a series of semi-structured qualitative interviews. Using grounded theory, an explanatory conceptual framework is derived, based on an extension of the “method-in-action” model, the application of which to WBSD has not been previously investigated in depth. It is proposed that this framework of WBSD issues is valuable in a number of ways to educators, researchers, practitioners, and method engineers.     

Equivalent Conditions for Convergence of Splittings of Non-Hermitian Indefinite Matrices

We present some sufficient and necessary conditions for convergent splitting of a non-Hermitian indefinite matrix. Some sufficient conditions to determinate a matrix with a (strongly) dominant symmetric part for a class of boundary value problem are also obtained. These results are applicable to identify the convergence of iterative methods for solving large sparse systems of linear equations.     

secG and temperature modulate expression of azide-resistant and signal sequence suppressor phenotypes of Escherichia coli secA mutants

SecA is a dynamic protein that undergoes ATP-dependent membrane cycling to drive protein translocation across the Escherichia coli inner membrane. To understand more about this process, azide-resistant (azi) and signal sequence suppressor (prlD) alleles of secA were studied. We found that azide resistance is cold sensitive because of a direct effect on protein export, suggesting that SecA-membrane interaction is regulated by an endothermic step that is azide inhibitable. secG function is required for expression of azide-resistant and signal sequence suppressor activities of azi and prlD alleles, and in turn, these alleles suppress cold-sensitive and export-defective phenotypes of a secG null mutant. These remarkable genetic observations support biochemical data indicating that SecG promotes SecA membrane cycling and that this process is dependent on an endothermic change in SecA conformation.     

A comparative cerebral blood flow study in a baboon model with acetazolamide provocation: 99mTc-HMPAO vs 123I(IMP)

Pharmacological interactions are important when nuclear medical procedures are applied to patients under drug therapy, or drug provocation. This study compares in baboon models (regional) cerebral blood flow [(r)CBF] results from 99mTc-HMPAO and 123I-iodoamphetamine [123I(IMP)] each with and without acetazolamide, the latter a suggested drug for testing cerebrovascular reserve. Expected differences in cerebral uptake were observed between the two radio-tracers without acetazolamide. The increase in tracer uptake resulting from acetazolamide is significantly enhanced for 123I(IMP), which could have diagnostic implications.     

The prospects of non-volatile phase-change RAM

Phase-change read-and-write memory (PRAM) is a promising memory that can solve the problems of conventional memory—scalability, read/write speed, and reliability. We will review the opportunities and technical challenges of PRAM. The most important challenge of PRAM is the reduction of the writing current. Various approaches to reduce the writing current will be reviewed and the prospects of PRAM are discussed.