Requirements Engineering and Process Modelling in Software Quality Management— Towards a Generic Process Metamodel

This paper examines the concept of Quality in Software Engineering, its different contexts and its different meanings to various people. It begins with a commentary on quality issues for systems development and various stakeholders' involvement. It revisits aspects and concepts of systems development methods and highlights the relevance of quality issues to the choice of a process model. A summarised review of some families of methods is presented, where their application domain, lifecycle coverage, strengths and weaknesses are considered. Under the new development era the requirements of software development change; the role of methods and stakeholders change, too. The paper refers to the latest developments in the area of software engineering and emphasises the shift from traditional conceptual modelling to requirements engineering and process metamodelling principles. We provide support for an emerging discipline in the form of a software process metamodel to cover new issues for software quality and process improvement. The widening of the horizons of software engineering both as a communication tool and as a scientific discipline (and not as a craft) is needed in order to support both communicative and scientific quality systems properties. In general, we can consider such a discipline as a thinking tool for understanding the generic process and as the origin of combining intuition and quality engineering to transform requirements to adequate human-centred information systems. We conclude with a schematic representation of a Generic Process Metamodel (GPM) indicating facets contributed by Software Engineering, Computer Science, Information Systems, Mathematics, Linguistics, Sociology and Anthropology. Ongoing research and development issues have provided evidence for influence from even more diverse disciplines.     

Microwave sintering of titanium diboride

Using a 2.45 GHz, 6 kW microwave furnace adapted for inert gas sintering, titanium diboride (TiB₂) can be rapidly microwave-sintered to >90% of theoretical density with sintering temperatures of 1900 to 2100 °C and soak times of 30 min or less. Densification behaviour with low-level additives was evaluated; 3 wt% chromium diboride (CrB₂) was an excellent sintering aid-grain growth inhibitor. A special covering system was required to produce oxidefree TiB₂. Specimen surface and interior temperatures were determined with a hole experiment. Comparison with conventional sintering indicates that microwave sintering of TiB₂-3 wt% CrB₂ occurs at lower temperatures (i.e., 200 °C lower) and can yield material with improved hardness, grain size, and fracture toughness.A portion of the material in this article was presented at a Symposium on Microwave Processing of Ceramics, 91st Annual Meeting of the American Ceramic Society, Indianapolis, Indiana, April 1989.Operated for the U.S. Department of Energy by Martin Marietta Energy Systems, Inc., under contract DE-AC05-84OR21400.     

Testing methods for X-machines: a review

The X-machine testing method has been developed as an application of the W-method to testing the control structure of an implementation, against a specification. The method was proven to demonstrate the equivalence of the behaviour of the two, subject to a number of conditions both a specification and an implementation are expected to satisfy, such as (1) determinism of the two and (2) that functions labelling arcs on a transition diagram of a specification control structure have been tested in advance. Since the original publication of the testing method, a number of extensions have been published, removing the restrictions mentioned above. This paper surveys the extensions of the X-machine testing method, for (1) testing of functions together with testing of a transition diagram, (2) equivalence testing of a non-deterministic implementation against a non-deterministic specification, (3) conformance testing of a deterministic implementation against a non-deterministic specification and (4) equivalence testing of a system of concurrently executing and communicating X-machines, against a specification. Received June 2004 Revised March 2005 Accepted March 2005 by J. Derrick, M. Harman and R. M. Herons     

Metal binding characterization and conformational studies using Raman microscopy of resin-bound poly(aspartic acid)

The metal binding capacities, conditional stability constants, and secondary structure of immobilized polyaspartic acid (PLAsp) (n = 6, 20, and 30) on TentaGel resin were determined when binding Mg2+, Co2+, Cd2+, and Ni2+. Metal binding to the synthesized peptides was evaluated using breakthrough curves from a packed microcolumn and flame atomic absorption spectrophotometry (FAAS) detection. The metal capacities reached values of 590, 2160, and 3710 mumol of metal/g of resin for the 6-mer, 20-mer, and 30-mer, respectively, and this resulted in 2-3 residues per metal for all peptides and metals tested. Surprisingly, the concentrated environment of the resin along with the spatial distribution of attachment groups allowed for most residues to participate in metal binding regardless of the peptide length. Conditional stability constants calculated using single metal binding isotherms indicated that binding strength decreased as the chain length increased on the resin. Raman microscopy on single beads was used to determine PLAsp secondary structure, and all peptides were of a mixed conformation (i.e., beta-sheets, alpha-helices, random chain, etc.) during neutral conditioning and metal binding. Uniquely, the longer 20-mer and 30-mer peptides showed a distinct change from a mixed conformation to beta-sheets and alpha-helices during metal release with acid. This study confirms that metal release by longer immobilized peptides is often assisted by a conformational change, which easily spoils the binding cavity, while shorter peptides may release metal primarily by H+ displacement.     

Effects of pH increases and sodium chloride additions on the acute toxicity of 2,4-dichlorophenol to the fathead minnow

The observable toxic effects produced by short-term exposure of fathead minnows (Pimephales promelas) to 2,4-dichlorophenol were reduced when the pH of the test water was increased by the addition of NaOH. After exposure for 192 h to 7.43 mg 2,4-dichlorophenol l^-1, the average survival of fathead minnows ranged from 28% at pH 7.57 to 100% at pH 9.08. Normal schooling behaviour was completely disrupted, and the equilibrium of most fish was affected after a 24-h exposure to 7.43 mg 2,4-dichlorophenol 1^-1 at pH 7.57, but neither schooling nor equilibrium were affected even after 192 h at pH 8.68 and 9.08. Schooling and swimming behaviour of fathead minnows exposed to 12.33 mg 2,4-dichlorophenol l^-1 were affected at all pH levels. Survival of these fish after 24 h ranged from 0% at pH 7.84–46% at pH 8.81. Sodium chloride in concentrations ranging from 0 to 13.9 mg l^-1 had no observable effects on the acute toxicity of 2,4-dichlorophenol to fathead minnows.     

Reduced serum vitamin D concentrations in healthy early-lactation dairy cattle

Cattle obtain vitamin D by ingestion or cutaneous exposure to UV light. Dairy cattle diets are frequently supplemented with vitamin D to compensate for limited sun exposure or during times of increased metabolic demands, such as the periparturient period, to maintain calcium homeostasis. Whether housing and supplemental vitamin D practices supply adequate amounts of vitamin D to optimally support the transition from gestation to lactation in dairy cattle is unknown. Our objective was to determine how serum vitamin D concentrations of dairy cows change with season, age, parity, and stage of lactation. Clinically healthy cows (n = 183) from 5 commercial dairies were enrolled in the study. Serum samples were collected at dry off, within 7 d of entering the close-up group, and within 7 d after calving (calving+7). Vitamin D status was determined by measuring serum 25-hydroxyvitamin D [25(OH)D] by radioimmunoassay. We performed repeated-measures mixed-effects linear regression to determine the effects of season, age, parity, and lactation stage (dry off, close-up, and calving+7) on 25(OH)D concentrations in serum. Bivariable analysis indicated that parity, age, and season were not associated with serum 25(OH)D concentrations. Sample period affected 25(OH)D concentrations, with the highest 25(OH)D levels at dry off (99.7 ± 1.9 ng/mL) followed by close up (93.8 ± 2.1 ng/mL), with the lowest levels at calving+7 (82.6 ± 1.7 ng/mL). These data showed a large depletion of 25(OH)D in dairy cattle postpartum compared with late prepartum, although the biological significance of this change in these healthy cattle is unclear. Consumption of serum 25(OH)D by immune system functions and calcium homeostasis in early lactation likely caused the reduction in serum 25(OH)D concentrations after calving. These results suggest that determining whether serum 25(OH)D concentrations are associated with the incidence of transition period disease is an appropriate next step. Assessing the effects of enhanced vitamin D supplementation of cows in early lactation on postpartum diseases may be warranted.     

Low concentrations of resveratrol inhibit Wnt signal throughput in colon-derived cells: implications for colon cancer prevention

Resveratrol is a bioflavonoid which is known to inhibit cell proliferation and induce apoptosis in cancer cell lines at concentrations above 50 muM. It also has colon cancer prevention activity in mouse models and possibly in humans. We have examined the effects of low concentrations of resveratrol on a specific signaling pathway, the Wnt pathway, which is activated in over 85% of sporadic colon cancers. Two colon cancer (HT29 and RKO) and one normal mucosa-derived (NCM460) cell lines were utilized. Cell proliferation was not affected by resveratrol at < or =40 microM for HT29 and NCM460 and <20 microM for RKO though Wnt signal throughput, as measured by a reporter construct, was reduced in RKO and NCM460 at concentrations as low as 10 microM (p < 0.001). This effect was most easily appreciated following Wnt pathway stimulation with Wnt3a conditioned medium and LEF1 or LEF1/beta-catenin transfection. Resveratrol did not inhibit Wnt throughput in mutationally activated HT29. Low concentrations of resveratrol significantly decreased the amount and proportion of beta-catenin in the nucleus in RKO (p = 0.002) and reduced the expression of lgs and pygoI, regulators of beta-catenin localization, in all cells lines. Thus, at low concentrations, in the absence of effects on cell proliferation, resveratrol significantly inhibits Wnt signaling in colon-derived cells which do not have a basally activated Wnt pathway. This inhibitory effect may be due in part to regulation of intracellular beta-catenin localization.     

Testing Conditions for Communicating Stream X-machine Systems

X-machines were proposed by Holcombe as a possible specification language and since then a number of further investigations have demonstrated that the model is intuitive and easy to use. In particular, stream X-machines (SXM), a particular class of X-machines, have been found to be extremely useful in practice. Furthermore, a method of testing systems specified as SXMs exists and is proved to detect all faults of the implementation provided that the system meets certain “design for test conditions”. Recently, a system of communicating SXMs was introduced as a means of modelling parallel processing. This paper proves that each communicating machine component can be transformed in a straightforward manner so that the entire system will behave like a single stream X-machine - the equivalent SXM of the system. The paper goes on to investigate the applicability of the SXM testing method to a system of communicating SXMs and identifies a class of communicating SXMs for which the equivalent SXM of the system meets the “design for test conditions”. Received November 1999 / Accepted in revised form June 2001     

Cultural influences on cognitive representations of conflict: Interpretations of conflict episodes in the United States and Japan.

This article integrates theory from the cognitive tradition in negotiation with theory on culture and examines cultural influences on cognitive representations of conflict. The authors predicted that although there may be universal (etic) dimensions of conflict construals, there also may be culture-specific (emic) representations of conflict in the United States and Japan. Results of multidimensional scaling analyses of U.S. and Japanese conflict episodes supported this view. Japanese and Americans construed conflicts through a compromise versus win frame (R. L. Pinkley, 1990), providing evidence of a universal dimension of conflict construal. As the authors predicted, Japanese perceived conflicts to be more compromise-focused, as compared with Americans. There were also unique dimensions of construal among Americans and Japanese (infringements to self and giri violations, respectively), suggesting that identical conflict episodes are perceived differently across cultures. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of the metal uptake of several algae strains in a multicomponent matrix utilizing inductively coupled plasma emission spectrometry

Three freshwater heat-killed, lyophilized blue-green algae strains have been characterized as to their ability to accumulate heavy metals with a focus on the utilization of these algae as an analytical preconcentration technique. This study examines the metal uptake in several multicomponent mixtures by using inductively coupled plasma optical emission spectrometry (ICP-OES). Six milligrams of a pure strain of algae was added to 20-mL aliquots of buffered (pH 5.5-6.5) multielement solutions containing 0.1, 0.5, 1.0, 2.0, and 4.0 mg/L of K, Mg, Ca, Fe, Sr, Co, Cu, Mn, Ni, V, Zn, As, Cd, Mo, Pb, and Se. All three algae strains exhibit relatively high adsorption affinities for Fe, Pb, and Cu, with uptake between 70 and 98% at the 4 ppm concentration level. Biosorption occurs for essentially every element with the relative affinities decreasing in the order Pb greater than Fe greater than Cu greater than Cd greater than Zn greater than Mn greater than Mo greater than Sr greater than Ni greater than V greater than Se greater than As greater than Co for Chlorella pyrenoidosa at the 4 mg/L concentration level. Although some minor differences were seen, the other algae strains (Stichococcus bacillaris and Chlamydomonas reinharti) displayed similar adsorption behavior over the concentration range studied, indicating similar cell wall binding sites. Langmuirian isotherms exhibited a minimum of two slopes over the concentration range of 0.1-4.0 mg/L, indicating the probable existence of at least two adsorption mechanisms.