The thermal stability of AlN

The thermal stability of AlN powders and thin films has been investigated using reflection high-energy electron diffraction (RHEED) and X-ray diffraction. AlN powder was treated thermally and chemically to assess the oxidation resistance of this compound and to identify the phases formed. The results show that AlN is stable up to 1000° C in air and remains stable up to 1400° Cin vacuo. -AIOOH is formed when AlN is treated with water at 100° C but AlN does not react readily with atmospheric moisture at room temperature. The thermal stability of thin films of AlN on GaAs has been evaluated at temperatures between 900 and 1100° C in a nitrogen atomosphere. It was found that AlN did not oxidize under these conditions. Pure AlN is a suitable encapsulant for GaAs at high annealing temperatures in an inert atmosphere.     

Designing autonomous robots

Autonomous robots are complex systems that require the interaction or cooperation of numerous heterogeneous software components. Nowadays, robots are getting closer to humans and as such are becoming critical systems that must meet safety properties including logical, temporal, and real-time constraints.     

Property preserving abstractions for the verification of concurrent systems

We study property preserving transformations for reactive systems. The main idea is the use of simulations parameterized by Galois connections (, ), relating the lattices of properties of two systems. We propose and study a notion of preservation of properties expressed by formulas of a logic, by a function mapping sets of states of a systemS into sets of states of a systemS'. We give results on the preservation of properties expressed in sublanguages of the branching time -calculus when two systemsS andS' are related via (, )-simulations. They can be used to verify a property for a system by verifying the same property on a simpler system which is an abstraction of it. We show also under which conditions abstraction of concurrent systems can be computed from the abstraction of their components. This allows a compositional application of the proposed verification method.This is a revised version of the papers [2] and [16]; the results are fully developed in [28].This work was partially supported by ESPRIT Basic Research Action REACT.Verimag is a joint laboratory of CNRS, Institut National Polytechnique de Grenoble, Université J. Fourier and Verilog SA associated with IMAG.     

Contribution of laser microdissection-based technology to proteomic analysis in hepatocellular carcinoma developing on cirrhosis

Hepatocellular carcinoma (HCC) is a major cause of cancer worldwide. Proteomic studies provide opportunities to uncover targets for the diagnosis and treatment of this disease. However, in HCC developing in a setting of cirrhosis, the detection of proteome alterations may be hampered by the increased cellular heterogeneity of tissue when analysing global liver homogenates. The aim of this study was to evaluate whether the identification of proteome alterations in these HCC cases was improved when the differential protein profile between tumour and non-tumour areas of liver was determined using hepatocytes isolated by laser microdissection (LM). Differential profiles established with LM-hepatocytes and liver section homogenates using 2-DE and MS exhibited noticeable differences: 30% of the protein spots with deregulated expression in tumorous LM-samples did not display any modification in homogenates; conversely 15% of proteins altered in tumorous homogenates were not impaired in LM-hepatocytes. These alterations resulted from the presence in cirrhotic liver of fibrotic stroma which displayed a protein pattern different from that determined in LM-hepatocytes. In conclusion, our data demonstrate the interest of LM in distinguishing between fibrotic and hepatocyte proteome alterations and thus the benefit of LM to proteome studies of HCC developing in a context of cirrhosis.     

Non-destructive testing to detect voids hidden behind the extrados of an arch bridge

The application of non-destructive dynamic testing to the assessment of brickwork arch bridges is described in this article. A procedure using impulsive one-shot excitation with frequency domain analysis is proposed for detection and sizing of voids hidden in the backfill above the extrados. Analysis by 3-d, dynamic finite element analysis proved the method’s efficacy. For experimental verification, various voids were formed at different positions; the bridge was tested both intact and with voids. The method detected and sized the voids. The frequency response function amplitude was the most reliable means of defect characterisation. The method appeared suitable for in situ arch assessment purposes.     

Structural,electronic and thermodynamic properties of SrxCd1−xO: A first-principles study

First principles calculations have been performed within the framework of density functional theory to investigate the structural, electronic and thermodynamic properties of Sr_xCd_1?xO ternary alloys. The exchange-correlation potential for structural properties was calculated by the standard local density approximation (LDA) and GGA (PBE), a more accurate nonempirical density functional generalized gradient approximation (GGA), as proposed by Wu and Cohen [Physical Review B 73 (2006) 235116], while for electronic properties, the Engel and Vosko GGA (EVGGA) and the modified Becke–Johnson (MBJ) of the exchange-correlation energy and potential, respectively, are used. Deviation of the lattice constants from Vegard's law and bulk modulus from linear concentration dependence (LCD) were observed for the ternary alloys. The MBJ band gaps values agree well with the available experimental results. In addition the thermodynamic stability of the alloys was investigated by calculating the critical temperatures of alloys.     

Automatic Generation of Invariants

When proving invariance properties of programs, one is faced with two problems. The first problem is related to the necessity of proving tautologies of the considered assertion language, whereas the second manifests itself in the need of finding sufficiently strong invariants. This paper focuses on the second problem and describes techniques for the automatic generation of invariants. The first set of these techniques is applicable to sequential transition systems and allows deriving so-called local invariants, i.e., predicates which are invariant at some control location. The second is applicable on networks of transition systems and allows combining local invariants of the sequential components to obtain local invariants of the global system.