Intravascular Ultrasound Tissue Characterization with Sub-class Error-Correcting Output Codes

Intravascular ultrasound (IVUS) represents a powerful imaging technique to explore coronary vessels and to study their morphology and histologic properties. In this paper, we characterize different tissues based on radial frequency, texture-based, and combined features. To deal with the classification of multiple tissues, we require the use of robust multi-class learning techniques. In this sense, error-correcting output codes (ECOC) show to robustly combine binary classifiers to solve multi-class problems. In this context, we propose a strategy to model multi-class classification tasks using sub-classes information in the ECOC framework. The new strategy splits the classes into different sub-sets according to the applied base classifier. Complex IVUS data sets containing overlapping data are learnt by splitting the original set of classes into sub-classes, and embedding the binary problems in a problem-dependent ECOC design. The method automatically characterizes different tissues, showing performance improvements over the state-of-the-art ECOC techniques for different base classifiers. Furthermore, the combination of RF and texture-based features also shows improvements over the state-of-the-art approaches.     

Resource management in LEO satellite networks

To provide truly global coverage needed by increased Personal Communication Services (PCS), a new generation of mobile satellite networks has been proposed. These low Earth orbit (LEO) mobile satellite networks handle multimedia traffic and can be used for non-real-time as well as real-time service to remote areas. Due to the many handoffs, resource management and connection admission control are important tasks for fair bandwidth sharing and QoS guarantees. Because the total link capacity has to be divided among several carriers and given the limited buffer capacity of the ATM switch, resource management is vital. It ensures the ability of the network to provide users with their negotiated QoS while protecting the network and the end-systems from congestion. We introduced a simple connection admission control (CAC) priority policy based on the delay and cell loss requirements for the investigated types of traffic. We took into account the handoff status of the satellite beams involved. Thus, we propose an onboard buffer architecture with separated buffers for new calls and intra-satellite handoff calls. The priority scheme applied is as follows: highest priority is given to CBR, followed by rt-VBR, nrtVBR and ABR.     

CRUISE research activities toward ubiquitous intelligent sensing environments

Wireless sensor networks are expected to be one of the key enabling technologies in the near future. Ubiquitous intelligent sensing environments have a promising potential to enhance the everyday life of citizens, bringing important social benefits for each person and for society as a whole. Substantial research has contributed to progress in this field. However, there are still gaps to be filled. This article presents an overview of the Creating Ubiquitous Intelligent Sensing Environments (CRUISE) project and identifies challenges in the research on WSNs. It focuses on outlining the consortium?s vision and strategy for the evolution of research. Key issues for target sensor network applications and current research orientations in CRUISE are described. Future work within the project focus areas is identified.     

Elastic wave fields in a half-plane with free-surface relief,tunnels and multiple buried inclusions

In this work, we study the elastic wave fields that develop in an isotropic half-plane which contains different types of heterogeneities such as free-surface relief, unlined and lined tunnels, as well as multiple buried inclusions. The half-plane is swept by traveling harmonic waves, namely pressure waves, vertically polarized shear waves and Rayleigh waves, as well as by waves emanating from an embedded source. The computational tool used is the direct boundary element method (BEM) with sub-structuring capabilities. Following development and numerical implementation of the BEM, two stages of work are performed, namely a detailed verification study followed by extensive parametric investigations. These last numerical simulations help determine the dependence of the elastic waves that develop along the surface of the half-plane, as well as of the dynamic stress concentration factors in the different types of buried inclusions, to the following key factors: geometry of the free-surface relief, geometry, depth of burial and separation distance of the inclusions, wavelength to inclusion diameter ratio and dynamic interaction phenomena between the multiple heterogeneities. In closing, the potential of the enhanced BEM formulation to treat dynamic soil-structure-interaction problems with the kind of complexity expected in realistic engineering applications is discussed.     

Effect of Co and Ce on silica supported manganese catalysts in the reactions of complete oxidation of n-hexane and ethyl acetate

Mono-component and bi-component catalysts, prepared by impregnation of silica with aqueous solution of Mn, Co, and Ce nitrates, were tested in the reactions of complete oxidation of n-hexane and ethyl acetate. The catalysts were characterized by powder X-ray diffraction, temperature-programmed reduction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy (FTIR). The catalytic activity is significantly increased by the combination between manganese and cobalt, which is explained as a result of the high mobility of lattice oxygen, the simultaneous presence of Mn⁴⁺?CMn³⁺ couple, decrease in the strength of the Co?CO bond, and the predominance of Co in the second oxidation state on the catalyst surface. The decrease in catalytic activity of Mn?CCe sample is attributed to the predominance of Ce on the surface and lower mobility of the lattice oxygen.     

Preparation of copolymers of p-Isopropenylcalix[8]arene and Styrene

Summary p-Isopropenylcalix[n]arenes are useful building blocks for the design of novel polymer architectures. This paper is the first report on copolymerization of p-isopropenylcalix[8]arene and styrene by free radical polymerization. An extensive study on the optimization of the reaction conditions (especially monomer to initiator ratio, initiator concentration, and duration of the process) was performed in order to prepare high molecular weight copolymers in good yield. Homopolymerizations were also carried out for comparison. The products obtained by homopolymerization of the monomers and their copolymerization were fractionated and each fraction was characterized by chromatographic (GPC and HLPC) and spectroscopic methods as UV, IR and ¹H NMR and analytical methods. Considering the molecular weight, spectroscopic and analytical data the most probable structure of the copolymer was proposed. Extraction of metal picrates from water into organic solvent was used to evaluate the ion binding capabilities of p-isopropenylcalix[8]arenestyrene and O-acetylated p-isopropenycalix[8]arenestyrene copolymers.     

Natural rubber filled SiC and B4C ceramic composites as a new NTC thermistors and piezoresistive sensor materials

A novel electrically conductive composite for NTC thermistor and piezoresistive sensor was successfully fabricated by homogeneously dispersing conductive SiC and B₄C in an insulating natural rubber (NR) matrix. The morphology of the composites was investigated by means of scanning electron microscopy, cross linking density (n), volume fraction of rubber (V_r), and interparticle distance among conductive phases (r_p). The influence of the filler concentrations on the mechanical properties such as modulus of elasticity (E); hardness shore A (H), and elongation at break (EB) were studied in details. The dependences of volume resistivity of NR based composites filled with B₄C and SiC as a function of fillers concentration was investigated. Temperature dependencies of volume resistivity were also measured to examine the possible application of the composites to polymer linear negative temperature (NTC) thermistors. Furthermore, the temperature dependencies of dielectric constant of the composites were studied. For practical application, the thermal stability of the composites was examined by means of resistivity temperature and pressure hysteresis cycle. In parallel, the conduction mechanism of conductivity of the composites was interpreted in terms of the computed the activation and hopping energy. The applicability of the composites to piezoresistive sensor was examined too. The good mechanical properties and thermal stability of NR composites behavior can be utilized for fabricating various electronic devices as NTC thermistors and piezoresistive sensor (i.e. transducers in pressure sensors). POLYM. COMPOS., 29:109–118, 2008. © 2007 Society of Plastics Engineers     

Anti-Idiotype scFv Localizes an Autoepitope in the Globular Domain of C1q

We addressed the issue of C1q autoantigenicity by studying the structural features of the autoepitopes recognized by the polyclonal anti-C1q antibodies present in Lupus Nephritis (LN) sera. We used six fractions of anti-C1q as antigens and selected anti-idiotypic scFv antibodies from the phage library “Griffin.1”. The monoclonal scFv A1 was the most potent inhibitor of the recognition of C1q and its fragments ghA, ghB and ghC, comprising the globular domain gC1q, by the lupus autoantibodies. It was sequenced and in silico folded by molecular dynamics into a 3D structure. The generated 3D model of A1 elucidated CDR similarity to the apical region of gC1q, thus mapping indirectly for the first time a globular autoepitope of C1q. The V_H CDR2 of A1 mimicked the ghA sequence GSEAD suggested as a cross-epitope between anti-DNA and anti-C1q antibodies. Other potential inhibitors of the recognition of C1q by the LN autoantibodies among the selected recombinant antibodies were the monoclonal scFv F6, F9 and A12.     

Synthetic kenyaite as catalyst support for hydrocarbon combustion

Synthetic kenyaite is prepared in the system K₂O–SiO₂–H₂O. It is modified with cobalt and platinum in order to obtain catalysts for complete oxidation of n-hexane and benzene. The prepared samples are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetry (TG), differential thermal analysis (DTA), temperature programmed reduction (TPR) and Fourier transformed infrared (FTIR) spectroscopy. Co is loaded on kenyaite using ammonia method and classical impregnation. Bimetallic Co–Pt possess higher catalytic activity than monometallic cobalt for the oxidation of benzene, while, for hexane oxidation, the monometallic cobalt catalysts exhibit higher or close activity to that of Co–Pt samples. The catalysts prepared by ammonia method have better performance due to finer dispersion of the metal particles on the surface of the support.