Using formal methods to increase confidence in a home network system implementation: a case study

A home network system consists of multiple networked appliances, intended to provide more convenient and comfortable living for home users. Before being deployed, one has to guarantee the correctness, the safety, and the security of the system. Here, we present the approach chosen to validate the Java implementation of a home network system. We rely on the Java Modelling Language to formally specify and validate an abstraction of the system. This is a substantially revised version of our paper that appeared in the proceedings of the Workshop On Leveraging Applications of Formal Methods, Verification and Validation (ISoLA), Poitiers-Futuroscope, France, December 2007.     

Effect of Surface Flaw Size on Fracture Strength of Alumina Ceramics

Semielliptical surface flaws of different sizes were introduced into Al₂O₃ by Knoop microhardness indentation. The specimens were fractured by four-point bending and the profiles of the indentation flaws were determined by observing the fracture surfaces with a scanning electron microscope. The relation between the indentation flaw size and the fracture strength could be well explained by applying the fracture-mechanics analysis for semielliptical surface flaw in bending. The calculated values of the as-indented critical stress intensity factor, K_IC, were lower than previously reported presumably because of the influence of the residual stresses produced by the indenter.     

Regulation of endothelial production of C-type natriuretic peptide by interaction between endothelial cells and macrophages

We demonstrated endothelial production of C-type natriuretic peptide (CNP), the third member of the natriuretic peptide family, and its regulation by cytokines, including tumor necrosis factor-alpha (TNF alpha). We thus proposed that CNP can control vascular tone and growth as an endothelium-derived relaxing peptide. We also revealed the marked elevation of plasma CNP concentration in patients with septic shock, in which TNF alpha plays a significant part. As the interaction between endothelial cells (EC) and monocytes-macrophages plays a pivotal role in the pathogenesis of atherosclerosis, we investigated the effect of coculture of EC and macrophages on endothelial production of CNP. We used a human monocytic leukemia cell line, THP-1, which differentiates into macrophages when treated with phorbol 12-myristate 13-acetate. The coculture of EC and THP-1-derived macrophages enhanced CNP secretion by more than 10-fold compared with the single culture of EC or the coculture of EC and THP-1 without phorbol 12-myristate 13-acetate treatment. Prevention of direct contact between EC and THP-1-derived macrophages did not attenuate the increase in CNP secretion. Northern blotting revealed the augmentation of CNP messenger RNA expression in EC in the coculture. We detected TNF alpha in the conditioned medium from the coculture of EC and THP-1-derived macrophages. Furthermore, anti-TNF alpha antibody inhibited the stimulation of CNP secretion in the coculture. CNP at a concentration of 1 nM did not stimulate cGMP production in EC or THP-1-derived macrophages, but it elevated cGMP production significantly in vascular smooth muscle cells. These results indicate that endothelial production of CNP is stimulated mainly by TNF alpha released from THP-1-derived macrophages in the coculture. Endothelial CNP at the enhanced level may be one of the vascular mediators to regulate local vascular tone and growth through cGMP production by vascular smooth muscle cells, suggesting the potential significance of endothelial CNP in atherosclerosis.     

XAFS measurement of gallium in DLC thin film fabricated by FIB-CVD method

We measured the florescence X-ray absorption fine structure (XAFS) spectra of gallium atoms in a diamond-like carbon (DLC) thin film deposited by focused ion beam-chemical vapor deposition (FIB-CVD). Ga K-edge XAFS spectra were measured by monitoring the Ga Kα line in the energy range of 9.9–11.5 keV. The radial distribution function was calculated from the Fourier transform of the extended X-ray absorption fine structure (EXAFS) oscillation that had been obtained by appropriately removing the background and normalization. The peak due to the carbon atoms nearest the central gallium atom was at 1.6 Å. A comparison of the experimentally measured EXAFS oscillation and one calculated by single scattering theory indicated that the coordination number around the central gallium atom and the interatomic distance between the central gallium atom and the carbon atom were ≈ 6.4 and ≈ 2.6 Å, respectively. The interatomic distances for FIB-CVD DLC thin films annealed for 1 h at 200 °C and at 400 °C were the same as the as-deposited film.     

Significance of ventricular myocytes and nonmyocytes interaction during cardiocyte hypertrophy: evidence for endothelin-1 as a paracrine hypertrophic factor from cardiac nonmyocytes

BACKGROUND: In cardiac hypertrophy, both excessive enlargement of cardiac myocytes and progressive interstitial fibrosis are well known to occur simultaneously. In the present study, to investigate the interaction between ventricular myocytes (MCs) and cardiac nonmyocytes (NMCs), mostly fibroblasts, during cardiocytes hypertrophy, we examined the change in cell size and gene expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) in cultured MCs as markers for hypertrophy in the neonatal rat ventricular cardiac cell culture system. METHODS AND RESULTS: The size of cultured MCs significantly increased in the MC-NMC coculture. Concomitantly, secretions of ANP and BNP into culture media were significantly increased in the MC-NMC coculture compared with in the MC culture (with the possible contamination of NMC <1% of MC). Moreover, in the MC culture, enlargement of MC and an increase in ANP and BNP secretions were induced by treatment with conditioned media of the NMC culture. A considerable amount of endothelin (ET)-1 production was detected in the NMC-conditioned media. BQ-123, an ET-A receptor antagonist, and bosentan, a nonselective ET receptor antagonist, significantly blocked the hypertrophic response of MCs induced by treatment with NMC-conditioned media. Angiotensin II (Ang II) (10(-10) to 10(-6) mol/L) and transforming growth factor-beta1 (TGF-beta1) (10(-13) to 10(-9) mol/L), both of which are known to be cardiac hypertrophic factors, did not induce hypertrophy in MC culture, but both Ang II and TGF-beta1 increased the size of MCs and augmented ANP and BNP productions in the MC-NMC coculture. This hypertrophic activity of Ang II and TGF-beta1 was associated with the potentiation of ET-1 production in the MC-NMC coculture, and the effect of Ang II or TGF-beta1 on the secretions of ANP and BNP in the coculture was significantly suppressed by pretreatment with BQ-123. CONCLUSIONS: These results demonstrate that NMCs regulate MC hypertrophy at least partially via ET-1 secretion and that the interaction between MCs and NMCs plays a critical role during the process of Ang II- or TGF-beta1-induced cardiocyte hypertrophy.     

Equibiaxial Stress Effect on Fracture Strength of Indented Soda-Lime Glass in Water Environment: An Examination for Dependence on Crack-Tip Blunting

Equibiaxial stress effects were observed in constant stressing rate tests of indented soda-lime glass in a water environment. To discuss whether the equibiaxial stress effects on fracture strenght in a water environment were caused by the blunting of crack tips by chemical reaction between the glass and moisture, the specimens with controlled surface flaws soaked in hot water to make the crack tip blunt were fractured under both uniaxial and equibiaxial tensile stresses under both vacuum and air environments. The biaxial strengthening observed under restricted subcritical crack growth indicates that equibiaxial stress effects in a water environment are caused by the rounding of the initial crack tip.     

Presence of Streptococcus DNA sequence in surgical specimens of gastric cancer

In Southern blot analysis using Mycoplasma 16S ribosomal DNA (rDNA) as a probe, positive signals were detected in DNA samples from surgical specimens of gastric cancers. The DNA that hybridized to Mycoplasma 16S rDNA was eluted from the gel, cloned and sequenced. The cloned sequence was identical to 16S rDNA of Streptococcus anginosus. In Southern blot analysis with the S. anginosus 16S rDNA fragment as a new probe, positive signals were detected in 9 (20%) out of 43 cases of gastric cancer.