On requirement verification for evolving Statecharts specifications

Software development processes have been evolving from rigid, pre-specified, and sequential to incremental, and iterative. This evolution has been dictated by the need to accommodate evolving user requirements and reduce the delay between design decision and feedback from users. Formal verification techniques, however, have largely ignored this evolution and even when they made enormous improvements and found significant uses in practice, like in the case of model checking, they remained confined into the niches of safety-critical systems. Model checking verifies if a system’s model \(\mathcal{M}\) satisfies a set of requirements, formalized as a set of logic properties \(\Phi\) . Current model-checking approaches, however, implicitly rely on the assumption that both the complete model \(\mathcal{M}\) and the whole set of properties \(\Phi\) are fully specified when verification takes place. Very often, however, \(\mathcal{M}\) is subject to change because its development is iterative and its definition evolves through stages of incompleteness, where alternative design decisions are explored, typically to evaluate some quality trade-offs. Evolving systems specifications of this kind ask for novel verification approaches that tolerate incompleteness and support incremental analysis of alternative designs for certain functionalities. This is exactly the focus of this paper, which develops an incremental model-checking approach for evolving Statecharts. Statecharts have been chosen both because they are increasingly used in practice natively support model refinements.     

Cytomorphological changes in the rabbit oviductal epithelium after human chorionic gonadotropin treatment

Progenitor cells were isolated from the developing human central nervous system (CNS), induced to divide using a combination of epidermal growth factor and fibroblast growth factor-2, and then transplanted into the striatum of adult rats with unilateral dopaminergic lesions. Large grafts were found at 2 weeks survival which contained many undifferentiated cells, some of which were migrating into the host striatum. However, by 20 weeks survival, only a thin strip of cells remained at the graft core while a large number of migrating astrocytes labeled with a human-specific antibody could be seen throughout the striatum. Fully differentiated graft-derived neurons, also labeled with a human-specific antibody, were seen close to the transplant site in some animals. A number of these neurons expressed tyrosine hydroxylase and were sufficient to partially ameliorate lesion-induced behavioral deficits in two animals. These results show that expanded populations of human CNS progenitor cells maintained in a proliferative state in culture can migrate and differentiate into both neurons and astrocytes following intracerebral grafting. As such these cells may have potential for development as an alternative source of tissue for neural transplantation in degenerative diseases.     

A survey on the design space of end-user-oriented languages for specifying robotic missions

Software and Systems Modeling - Mobile robots are becoming increasingly important in society. Fulfilling complex missions in different contexts and environments, robots are promising instruments to...     

bcl-2 but not p53 expression is associated with resistance to chemotherapy in advanced breast cancer

Programmed cell death is an important determinant of the response to chemotherapy. Among the factors controlling this process, a significant role is played by bcl-2 and p53, the expression of which, together with estrogen receptor content and tumor proliferative activity, was investigated by means of immunohistochemistry in 55 advanced breast cancer patients (median age, 60 years; range, 25-71 years). Analysis of bcl-2 expression identified two groups of patients with a significant difference in response rate. A total of 17 patients (31%) responded to chemotherapy (5 had a complete response and 12 had a partial response): 14 of 32 (44%) bcl-2-negative patients (< 40% stained cells) and only 3 of 23 (13%) bcl-2-positive patients (> or = 40% of stained cells; P = 0.019 by Fisher's exact test). The two groups were well balanced in terms of age, performance status, disease-free survival, menopausal status, and type of chemotherapy. bcl-2-negative tumors showed a tendency toward a higher p53 expression and proliferation rate, whereas an excess of bone as the dominant disease site was evident among the bcl-2-positive ones. However, the only variable to result significantly different between the two groups was estrogen receptor expression (P = 0.004). A multivariate logistic regression model showed that bcl-2 maintained its power of discriminating two groups with a different probability of responding to chemotherapy, although the greatest contribution was given by dominant disease site and type of chemotherapy. In conclusion, the results of this study suggest a possible role for bcl-2 in predicting resistance to chemotherapy.     

The ForeMoSt approach to building valid model-based safety arguments

Software and Systems Modeling - Safety assurance cases (ACs) are structured arguments designed to comprehensively show that a system is safe. ACs are often model-based, meaning that a model of the...     

Contribution of confocal laser scanning microscopy to glycochemistry of mouse and rat submandibular glands by single and double lectin staining

The localization of individual glycosidic residues in the mouse and rat submandibular glands was examined using confocal laser scanning microscopy (CLSM). For these organs we tested some procedures of fixation and embedding to better understand the distribution of some lectin-probes inside well preserved secretory cells and observed that fixation and inclusion steps did not influence appreciably the location and intensity of the reactive sites. The fixation mixture of 4% paraformaldehyde, 1% glutaraldehyde and 0.2% picric acid produced the most satisfactory results. In specimens labeled with PNA-, Con A-, LTA-FITC and WGA-, DBA-TRITC lectins, the convoluted granular tubules (CGT) proved to be composed of secretory granules with high-density lectin labeling. The complex organization of secretory glycocomponents within the granule matrix was further resolved by double labeling and dual scanning experiments. Some lectins exhibited colocalization while others displayed differential localization providing information about the occurrence of O- and N-linked glycoconjugates. The CLSM technique applied to fluorochrome-conjugated lectins also revealed a more marked dimorphism in the rat rather than in the mouse submandibular gland. In particular, the male rat submandibular gland was found to consist of CGT heterogeneous cell populations, while the mouse submandibular gland did not show glycochemical differences between cells. Female rats exhibited a lectin profile very different from that of female mouse.