A case study comparing defect profiles of a reused framework and of applications reusing it

The benefits of software reuse have been studied for many years. Several previous studies have observed that reused software has a lower defect density than newly built software. However, few studies have investigated empirically the reasons for this phenomenon. To date, we have only the common sense observation that as software is reused over time, the fixed defects will accumulate and will result in high-quality software. This paper reports on an industrial case study in a large Norwegian Oil and Gas company, involving a reused Java class framework and two applications that use that framework. We analyzed all trouble reports from the use of the framework and the applications according to the Orthogonal Defect Classification (ODC), followed by a qualitative Root Cause Analysis (RCA). The results reveal that the framework has a much lower defect density in total than one application and a slightly higher defect density than the other. In addition, the defect densities of the most severe defects of the reused framework are similar to those of the applications that are reusing it. The results of the ODC and RCA analyses reveal that systematic reuse (i.e. clearly defined and stable requirements, better design, hesitance to change, and solid testing) lead to lower defect densities of the functional-type defects in the reused framework than in applications that are reusing it. However, the different “nature” of the framework and the applications (e.g. interaction with other software, number and complexity of business logic, and functionality of the software) may confound the causal relationship between systematic reuse and the lower defect density of the reused software. Using the results of the study as a basis, we present an improved overall cause–effect model between systematic reuse and lower defect density that will facilitate further studies and implementations of software reuse.

Adoption of open source software in software-intensive organizations – A systematic literature review

ContextOpen source software (OSS) is changing the way organizations develop, acquire, use, and commercialize software.ObjectiveThis paper seeks to identify how organizations adopt OSS, classify the literature according to these ways of adopting OSS, and with a focus on software development evaluate the research on adoption of OSS in organizations.MethodBased on the systematic literature review method we reviewed publications from 24 journals and seven conference and workshop proceedings, published between 1998 and 2008. From a population of 24,289 papers, we identified 112 papers that provide empirical evidence on how organizations actually adopt OSS.ResultsWe show that adopting OSS involves more than simply using OSS products. We moreover provide a classification framework consisting of six distinctly different ways in which organizations adopt OSS. This framework is used to illustrate some of the opportunities and challenges organizations meet when approaching OSS, to show that OSS can be adopted successfully in different ways, and to organize and review existing research. We find that existing research on OSS adoption does not sufficiently describe the context of the organizations studied, and it fails to benefit fully from related research fields. While existing research covers a large number of topics, it contains very few closely related studies. To aid this situation, we offer directions for future research.ConclusionThe implications of our findings are twofold. On the one hand, practitioners should embrace the many opportunities OSS offers, but consciously evaluate the consequences of adopting it in their own context. They may use our framework and the success stories provided by the literature in their own evaluations. On the other hand, researchers should align their work, and perform more empirical research on topics that are important to organizations. Our framework may be used to position this research and to describe the context of the organization they are studying.     

Three‐dimensional numerical modelling of the flushing process of the Kali Gandaki hydropower reservoir

Sediments filling reservoirs is a common problem in the world today, with an estimated 1% of the capacity of hydropower reservoirs being lost annually through sedimentation. One of the most used techniques for reducing this problem is reservoir flushing. During a flood, the water level is drawn down, causing increased velocities, therefore facilitating erosion and sediment transport. During the flushing, water from the reservoir will be lost, resulting in significant economic implications for the reservoir owner. The success of reservoir flushing depends on several parameters, including water discharge, sediment properties and reservoir geometry. This study describes the use of Computational Fluid Dynamics (CFD) as a modern method to predict the reservoir flushing process. A three‐dimensional numerical model (SSIIM 2), with an adaptive, non‐orthogonal and unstructured grid has been used. Through the application of special modified algorithms (e.g., wetting/drying, free water surface), numerical modelling of sediment movement can be an alternative for planning and optimizing the flushing process for complex reservoir geometries. The numerical model was tested against data from a physical model study of the Kali Gandaki hydropower reservoir in Nepal. The total quantity of flushed out sediments, and the bed deformation in six cross‐sections, were compared, highlighting a good correspondence between the results. These include the cross‐sectional shape of a 90‐degree bend, for which secondary currents influenced the results. The study indicates that numerical models might become a useful tool for reservoir flushing predictions.     

Liquid Loss as Effected by Post mortem Ultrastructural Changes in Fish Muscle: Cod (Gadus morhuaL) and Salmon (Salmo salar)

This study was performed in order to assess the effect of early post mortem structural changes in the muscle upon the liquid-holding capacity of wild cod, net-pen-fed cod (fed cod) and farmed salmon. The liquid-holding capacity was measured by a low speed centrifugation test. Transmission electron microscopy was used to discover ultrastructural changes both in the connective tissue and in the myofibrils. Differential scanning calorimetric thermograms of the muscle proteins were recorded to elucidate whether fundamental differences did exist between the proteins of the raw material tested. Multivariate statistics were used to explicate the main tendencies of variations in the thermograms. The salmon muscle possessed much better liquid-holding properties than the cod muscle, and wild cod better than fed cod regardless of the storage time. Both fed cod and farmed salmon, underwent the most severe structural alterations, probably caused by the low muscle pH values. The higher liquid-holding capacity of the salmon muscle was related to species specific structural features and better stability of the muscle proteins. The myofibrils of the salmon muscle were denser and intra- and extracellular spaces were filled by fat and a granulated material. The differences in thermograms of muscle from wild and fed cod were largely explained by the variations in pH. The severe liquid loss of fed cod is due to a low pH induced denaturation and shrinkage of the myofibrils. Post mortem degradation of the endomysial layer and the sarcolemma may have further facilitated the release of liquid.     

Comparison of composition, enzyme activity and selected functional properties of potato proteins isolated from potato juice with two different expanded bed resins

Protein concentrates prepared by expanded bed adsorption (EBA) chromatography from industrial potato juice (PJ) were analysed for chemical composition, color, enzyme activities, thermal properties and selected functional properties (solubility and emulsifying stability). Two EBA multi-modal resins, MIMO I-45 and MIMO 1300 (UpFront Chromatography), were employed under various pH conditions resulting in four potato protein concentrates, A-D. Concentrate B contained an electrophoretically pure protease inhibitor fraction (20-21 kDa), whereas concentrate A, C and D contained both patatin (41 kDa) and protease inhibitors. The potato protein concentrates were explored for the presence of transitions from native to denatured states using differential scanning calorimetry (DSC). Concentrate C had lower heat of transition (ΔH) and T-onset than the other concentrates. The concentrate containing protease inhibitors exhibited the highest denaturation temperature and enthalpy. All concentrates differed significantly (P < 0.05) in color brightness, with concentrate B and D emerging as the brightest. The solubility of the concentrates was evaluated at pH 6 and pH 4.5. All concentrates had lower solubility at pH 4.5 than at pH 6 (70-80%). The stability of emulsions (1% protein, 20% oil, 0.08% xanthan gum) against creaming was analysed with a new method based on the Single electrode Capacitance Probe (SeCaP) technology. Small differences among concentrates were observed by the new SeCaP method.     

宁要模糊的正确，不要明确的错误：石油勘探和开采行业的新决策方法

本文讨论了运用整体综合方法评价不确定性对油气投资决策影响的必要性。我们认为，仅对于投资决策评价各种要素的综合性常规精确模型增添处理不确定性的功能，是不能有效达到上述目的的。此外我们还认为，这种方法即使是可行的，也并不是人们所期望的。因此我们提出了在决策支持系统中引入整体和概率评价方法的概念。这种整体分析方法有两种要素。一种是技术要素，它综合了各种评价和决策工具。另一种是模拟思路要素，它全面考虑了不确定性的广度和规模。为了更全面、准确和严格地评价不确定性对投资决策过程的影响，这种方法要牺牲一部分技术精度和细节。这种系统的基本组成主要有各领域的简化要素模型、蒙特卡罗模拟工具以及模拟语言，可用于满足用户的特殊要求、综合不同要素之间的相互依赖关系、执行决策逻辑以及作为学习结果更新信息。文中说明了这种系统如何识别哪种不确定性对决策影响最大、如何评价信息采集（数据、技术分析）的价值以及如何在缓解和／或利用不确定性的下一步计划中促进灵活性。其他应用还有优化开发情景、评价真实的选择情景以及为投资组合分析的输入数据生成统一的风险现金流。这种系统的应用已通过其综合技术决策和经营决策的能力，使多学科资产管理团队的工作实现了真正的以价值驱动为重点。     

Proton Conductivity in Solid Solution 0.7(CaWO4)–0.3(La0.99Ca0.01NbO4) and Ca(1−x)LaxW(1−y)TayO4

The conductivity of nominal CaWO₄, CaW_0.99Ta_0.01O_4–δ, 0.7(CaWO₄)–0.3(La_0.99Ca_0.01NbO_4–δ), and Ca_0.9La_0.1WO_4+δ has been studied by means of a.c. impedance measurements. Proton conductivity was observed for CaW_0.99Ta_0.01O_4–δ, which displayed exothermic hydration with enthalpy and entropy of –82 kJ/mol and –120 J/molK, respectively. The proton mobility in CaW_0.99Ta_0.01O_4–δ was low, with enthalpy and preexponential factor of mobility of 82 kJ/mol and 0.7 cm²K/Vs. The high enthalpy of mobility is interpreted to reflect association between the acceptor dopant and protonic defects, whereas the low preexponential factor of mobility may reflect a lower proton concentration than assumed. Rietveld refinement indicated low solubilities of La on Ca‐site and Ta on W‐site. Proton conductivity was also observed in undoped CaWO₄, however, not in Ca_0.9La_0.1WO_4+δ. The conductivity of 0.7(CaWO₄)–0.3(La_0.99Ca_0.01NbO_4–δ) behaved much like that of undoped LaNbO₄, likely due to a very low acceptor dopant concentration.     

High-Temperature Proton Conductivity in Acceptor-Substituted Rare-Earth Ortho-Tantalates, LnTaO4

The electrical properties of 1 mol% Ca-doped LnTaO₄ (Ln=La, Nd, Gd, Er) have been characterized by AC impedance spectroscopy and by the EMF transport number technique as a function of the oxygen pressure and the water vapor pressure from 300° to 1200°C. Protons, oxide ions, electron holes, and electrons contribute to the total conductivity, depending on the conditions. Ionic conductivity predominates under reducing and weakly reducing conditions, with protons prevailing in wet atmospheres up to temperatures of around 1000°C. p -type electronic conductivity prevails at high temperatures under oxidizing conditions. The conductivity behavior has been interpreted according to a point-defect model where protons and oxygen vacancies charge compensate the acceptor doping. Thermodynamic and transport parameters have been extracted based on the changes in total conductivity upon variations in the conditions. The hydration enthalpy becomes increasingly negative with increasing oxide ion density from LaTaO₄ to ErTaO₄.     

Some comments on “concurrent readers and writers”

Summary A more compact and efficient algorithm for synchronization of concurrent readers and writers is presented, and which grants writers effective priority over readers. A synchronization primitive P ^*, which only decrements a semaphore value by one, is also described.     

An ultrastructural study of cryofractured myocardial cells with special attention to the relationship between mitochondria and sarcoplasmic reticulum

A comparative study of various cryofracturing techniques has been conducted on the mammallian myocardial cell. Quench freezing of fresh or fixed tissue in melting Freon 22 resulted in severe cellular damage due to ice crystallization. Fixation with Karnovsky's fixative prior to quenching had no modifying effect on the size and distribution of the ice crystals. The crystals were orientated primarily in the direction of the long axis of the myofibrils, manifested as empty tube-like structures in the scanning electron microscope (SEM). Regular cross-bridging often seen at the Z-band levels indicated that ice crystals, at least in some portions of the cells, were confined within the sarcomere. Within the same cell the size of the ice crystals could vary considerably. Treatment of the tissue with polyvinylpyrrolidone (PVP) prior to rapid freezing had no noticeable cryoprotective effect. The surface of the thin layer of PVP surrounding the freeze dried tissue appeared amorphous in the SEM. However, the first evidence of ice crystallization was found a few micrometres under the surface. The freezing artefacts were completely circumvented if the cryofracturing was carried out on ethanol-impregnated or on critical point dried material. While the first method resulted in a smooth fracture plane passing through the cell structures, the intracellular fracture plane of the critical point dried material followed the surface of the cell organelles. Separation of the cell organelles caused by freezing or by critical point drying revealed thread-like structures extending from the mitochondrial surface. Re-examination of SEM-processed material in the transmission electron microscope (TEM) revealed that these structures were part of the sarcoplasmic reticulum (SR), and that a close contact between the SR and the outer mitochondrial membrane existed. TEM of conventional prepared material revealed that strands of electron-dense material, here named ‘mito-reticular junctional fibres’, bridged the narrow gap between the mitochondrial surface and the SR. It is suggested that these fibres have a specific anchoring function.