Feature-interaction detection based on feature-based specifications

Formal specification and verification techniques have been used successfully to detect feature interactions. We investigate whether feature-based specifications can be used for this task. Feature-based specifications are a special class of specifications that aim at modularity in open-world, feature-oriented systems. The question we address is whether modularity of specifications impairs the ability to detect feature interactions, which cut across feature boundaries. In an exploratory study on 10 feature-oriented systems, we found that the majority of feature interactions could be detected based on feature-based specifications, but some specifications have not been modularized properly and require undesirable workarounds to modularization. Based on the study, we discuss the merits and limitations of feature-based specifications, as well as open issues and perspectives. A goal that underlies our work is to raise awareness of the importance and challenges of feature-based specification.     

High-level expression of a viscotoxin in Arabidopsis thaliana gives enhanced resistance against Plasmodiophora brassicae

PURPOSE: Primary open-angle glaucoma (POAG) is associated with a decreased content of hyaluronan in the trabecular meshwork and in the juxtacanalicular connective tissue. In this study, the authors examined selected regions of the anterior segment to localize and determine the content of CD44H, a transmembrane multifunctional glycoprotein and the principal receptor of hyaluronan. METHODS: Sections of ethanol-fixed anterior segments of six POAG and six normal postmortem eyes were analyzed by immunostaining with and without the nonionic detergent Triton X-100, using the CD44H monoclonal antibody, and the avidin/biotin complex. They were visualized by Vector VIP substrate and were quantitated by computer-aided color image analysis. RESULTS: CD44H was expressed in all regions. Statistically significant decreased content of CD44H was observed in the POAG regions compared with normal regions--ciliary muscle (P < 0.001), ciliary stroma (P < 0.001), anterior iris (P < 0.05), iris root (P < 0.05), and trabecular meshwork (P < 0.05)--and in a subgroup of nonlaser POAG juxtacanalicular connective tissue (P < 0.05) and trabecular meshwork (P < 0.01). In sections treated with Triton X-100 a further increase in immunostaining was observed in normal eyes. As evidenced by scattergram plots of the ciliary body stroma region of the change in the optical density of CD44H between pretreatment with Triton X-100 and without Triton X-100 (y axis) versus the optical density of CD44H without Triton X-100 (x axis), individual cases of POAG were separated from normals. CONCLUSIONS: These results indicate that CD44H may represent a marker of POAG and an etiologic factor in the POAG disease process.     

Future perspectives of biomaterials for dental restoration

The development of biomaterials that can be used to substitute metals in dental restorations represents the main challenge of future research activities until the year 2020. Therefore, the authors will focus on the presentation of two types of biomaterials for dental restoration: glass-ceramics and sintered ceramics. Dental biomaterials must have a highly aesthetic appearance that is comparable to that of natural teeth. Furthermore, they must be more durable than natural teeth and show good mechanical properties at ambient temperatures.Based on the state of the art and the latest research activities, the presentation is focused on glass-ceramics with high toughness, glass-ceramics with optical properties comparable to those of natural teeth and glass-ceramics that are processed with preferred techniques, for example, those which are moulded on different types of high-strength substrate materials. In addition, high-strength and high-toughness materials such as lithium disilicate glass-ceramics can be processed either by moulding or by a new method, that is, machining. Possible directions will be presented for moulding different types of glass-ceramics such as fluoroapatite containing glass-ceramics on high-toughness substrates made of glass-ceramics or very tough sintered ceramics.The focal point of this presentation is the demonstration of the high-strength and high-toughness sintered ceramics of the ZrO₂ type. The preferred processing method of this type of biomaterials for dental restoration is machining using CAD/CAM technologies. Future activities will be focused on improving the quality of the ZrO₂-type biomaterial. At present ZrO₂ ceramics are white opaque. One of the main aims is to achieve optical properties comparable to those of natural teeth in ZrO₂ ceramic. Therefore, the material has to be developed in special dental colours with the same mechanical properties and good durability as that of the white ZrO₂. The authors will show future directions for developing coloured ZrO₂ sintered ceramics.Future research activities will be focused on gaining a better understanding of the phenomena and mechanisms of toughening glass-ceramics and ceramics. With the acquired knowledge on the toughening mechanisms, new directions for developing ceramics until the year 2020 will be explored. The technology to achieve this goal will be applied nanotechnology.     

The production of porous glassy carbon membranes from swift heavy ion irradiated Kapton

A porous glassy carbon membrane was obtained by first producing ion tracks in a polymeric Kapton film by irradiation with high energy krypton or xenon ions. Pores are formed by selective chemical etching along the ion tracks, and then the film was converted to glassy carbon by heat treatment at 1000 °C under an inert atmosphere. The process yields a self-supported glassy carbon thin membrane. The density of the pores in the membrane depends on the ion irradiation fluence, and the length, diameter and shape of the pores could be controlled by the ion energy and etching procedure.     

Measuring and modeling programming experience

Programming experience is an important confounding parameter in controlled experiments regarding program comprehension. In literature, ways to measure or control programming experience vary. Often, researchers neglect it or do not specify how they controlled for it. We set out to find a well-defined understanding of programming experience and a way to measure it. From published comprehension experiments, we extracted questions that assess programming experience. In a controlled experiment, we compare the answers of computer-science students to these questions with their performance in solving program-comprehension tasks. We found that self estimation seems to be a reliable way to measure programming experience. Furthermore, we applied exploratory and confirmatory factor analyses to extract and evaluate a model of programming experience. With our analysis, we initiate a path toward validly and reliably measuring and describing programming experience to better understand and control its influence in program-comprehension experiments.     

Introduction to a tough,strong and stable Ce-TZP/MgAl2O4 composite for biomedical applications

The processing of a new ceria-doped tetragonal zirconia polycrystal-based (Ce-TZP) composite and its microstructural and mechanical features are presented. Slip casting and die pressing were used to process commercially available Ce-TZP and MgAl₂O₄ powders into a dense ceramic composite. The absence of tetragonal to monoclinic transformation under hydrothermal conditions was assessed during accelerated aging tests. Biaxial flexural strength and fracture toughness values of more than 900 MPa and 15 MPa √m, respectively were measured, showing that phase transformation toughening of zirconia is maintained in the composite, while the inter/intragranular dispersion of nano-scaled magnesia spinel leads to strengthening of the Ce-TZP matrix. Flaw tolerance is attained, since the strength appears to be transformation dependent. These properties allow the composite to be used in the fabrication of various load-bearing components by employing conventional processing methods and sintering, for example for structural biomedical applications.     

Phase‐Field Simulation of Solidification and Solid‐State Transformations in Multicomponent Steels

Calculating microstructures for technical materials is an ambitious task which not only implies different length scales but also the complex thermodynamic properties of multicomponent and multiphase alloys. We report some of the recent progress in simulating microstructure evolution in multicomponent steels using the multiphase‐field software MICRESS®. Several applications are reviewed in order to demonstrate the current status of applied phase‐field techniques.