Analysis of the Electromagnetic Interaction Between a Resonator and a Lossy Dielectric Body as a First Theoretical Approach to Noninvasive Heart Movement Detection

In this paper the electromagnetic interaction between a resonator and a lossy dielectric body is examined by means of a simple model suitable for computer simulation; the body was assumed to have a revolution form and the resonator was electromagnetic coupled to the body by its inductive element constituted by a planar circular or spiral coil. On the basis of the model a computer program was derived which allows a simple numerical evaluation of the variation in the resonant frequency caused by the interaction mentioned above.     

Immunocytochemical study of alpha 1 and beta 2/3 subunits of GABAA receptors in freehand isolated vestibular Deiters' neurons

Vestibular Deiters' neurons have been isolated from bovine brain by the Hydén's freehand dissection technique and challenged with monoclonal antibodies directed toward the alpha 1 and beta 2/3 subunits of the GABAA receptors. Subsequent challenge with fluorescent secondary antibodies and confocal microscopy allowed the study of the cellular distribution of such subunits. In Deiters' neurons the beta 2/3 subunit displayed a clear presence all along the cell body profile and the initial parts of the dendrites. The alpha 1 subunit was found highly present all over the cell interior except the nuclear profiles. The strong presence inside the cells possibly masked its presence on the plasma membrane. However, in part of the cells studied a distinct presence on the plasma membrane was evident. This subunit was visualized also all along the long dendrites of these neurons. The approach we describe here, involving freehand isolated mature neurons from adult animals, may allow a better characterization of the tridimensional distribution of different types of neuronal GABAA receptors in the respect of the approach with brain slices.     

Sensitivity Analysis Methods to Design Optimal Ship Hulls

Automatic procedures for the design of ship hull geometries yielding minimal wave resistance and wave breaking are an attractive opportunity from both the economical and practical standpoints. Estimating the cost function gradient according to the Sensitivity Equation and Adjoint Methods (SEM, AM) instead of using the standard finite difference approximations has the potential of reducing the computational cost of the overall optimization procedure. Aim of this paper is to assess the actual extent of the cost reduction. Speed-up factors of up to 3.3 have been obtained in the evaluation of the cost function gradient and of about 1.6 in the overall optimization procedure applied to an optimal shape design problem of an existing tanker ship. The SEM and AM methods perform better than finite differences mainly because of (i) the smaller number of flow solutions needed to compute the cost function gradient and (ii) the opportunity of using the same LU factored matrix for both the flow solver and the SEM or AM equations, a circumstance arising as a consequence of having chosen a linearized potential flow model of the 3D free-surface problem.     

Self-assembled nanoscale biosensors based on quantum dot FRET donors

The potential of luminescent semiconductor quantum dots (QDs) to enable development of hybrid inorganic-bioreceptor sensing materials has remained largely unrealized. We report the design, formation and testing of QD-protein assemblies that function as chemical sensors. In these assemblies, multiple copies of Escherichia coli maltose-binding protein (MBP) coordinate to each QD by a C-terminal oligohistidine segment and function as sugar receptors. Sensors are self-assembled in solution in a controllable manner. In one configuration, a beta-cyclodextrin-QSY9 dark quencher conjugate bound in the MBP saccharide binding site results in fluorescence resonance energy-transfer (FRET) quenching of QD photoluminescence. Added maltose displaces the beta-cyclodextrin-QSY9, and QD photoluminescence increases in a systematic manner. A second maltose sensor assembly consists of QDs coupled with Cy3-labelled MBP bound to beta-cyclodextrin-Cy3.5. In this case, the QD donor drives sensor function through a two-step FRET mechanism that overcomes inherent QD donor-acceptor distance limitations. Quantum dot-biomolecule assemblies constructed using these methods may facilitate development of new hybrid sensing materials.     

Quantum Erasure of Decoherence

We consider the classical algebra of observables that are diagonal in a given orthonormal basis, and define a complete decoherence process as a completely positive map that asymptotically converts any quantum observable into a diagonal one, while preserving the elements of the classical algebra. For quantum systems in dimension two and three any decoherence process can be undone by collecting classical information from the environment and using such an information to restore the initial system state. As a relevant example, we illustrate the quantum eraser of Scully et al. [Nature 351, 111 (1991)] as an example of environment-assisted correction, and present the generalization of the eraser setup for d-dimensional systems. Presented at the 38th Symposium on Mathematical Physics “Quantum Entanglement & Geometry”, Toruń, June 4–7, 2006.     

A Graph Abstract Machine Describing Event Structure Composition

Event structures, Game Semantics strategies and Linear Logic proof-nets arise in different domains (concurrency, semantics, proof-theory) but can all be described by means of directed acyclic graphs (dag's). They are all equipped with a specific notion of composition, interaction or normalization.We report on-going work, aiming to investigate the common dynamics which seems to underly these different structures.In this paper we focus on confusion free event structures on one side, and linear strategies [Jean-Yves Girard. Locus solum. Mathematical Structures in Computer Science, 11:301–506, 2001, C. Faggian and F. Maurel. Ludics nets, a game model of concurrent interaction. In Proc. of LICS'05 (Logic in Computer Science). IEEE Computer Society Press, 2005] on the other side. We introduce an abstract machine which is based on (and generalizes) strategies interaction; it processes labelled dag's, and provides a common presentation of the composition at work in these different settings.     

A minimum-time control strategy for torque tracking in permanent magnet AC motor drives

A minimum-time torque control strategy for permanent-magnet AC motor drives is presented. The proposed technique neither requires the solution of a HJB-type equation, which would be practically unfeasible, nor uses Pontryagin's maximum principle. Instead, the solution is obtained by an ad hoc procedure based on the computation of reachability and controllability sets. In principle, the optimal control strategy can be carried out by iteratively solving a fourth-degree polynomial equation. For its efficient implementation, an algorithm based on Sturm sequences is suggested. The sequence of online operations required by the algorithm for a given tolerance on the optimal time is illustrated. The method has been tested on a laboratory prototype. Experimental results show the effectiveness of the technique.     

First data from the EGLE experiment onboard the ISS

EGLE is a wide frequency band search- coil magnetometer designed and built at the Roma Tre University. It has been installed onboard the ISS by the Italian astronaut Roberto Vittori on April 25, 2005 within the LAZIO- EGLE experiment carried out during the ENEIDE Soyuz mission. The scope of the experiment is to test EGLE in space and to investigate geomagnetic field variations. The main applications of EGLE are the study of electromagnetic environment inside the ISS, the correlation of magnetic field data with particle fluxes detected by LAZIO particle detector, and the monitoring of ionospheric perturbations possibly caused by Earth seismic activity. Since continuous electromagnetic field measurements on board the ISS are important for diverse space applications, a magnetometer with a suitable design is requested. Appropriate solutions for these applications, which have been adopted by EGLE, are in particular the use of 1- Wire technology and the possibility to detect by means of a search- coil magnetometer a large portion of the ULF frequency band, usually measured by flux- gate probes. To investigate the topside ionosphere electromagnetic environment and stability of Van Allen radiation belts in relation with seismic and anthropogenic electromagnetic emissions, a specific satellite mission (the ESPERIA project) has been designed for the Italian Space Agency (ASI), and up to now a few instruments of its payload have been built and tested in space. One of them is exactly the EGLE search- coil magnetometer. The first magnetic observations performed by this instrument reveal to be promising and demand for a further and deeper analysis based on a longer time series of data.     

M‐matrices and global convergence of discontinuous neural networks

The paper considers a general class of neural networks possessing discontinuous neuron activations and neuron interconnection matrices belonging to the class of M‐matrices or H‐matrices. A number of results are established on global exponential convergence of the state and output solutions towards a unique equilibrium point. Moreover, by exploiting the presence of sliding modes, conditions are given under which convergence in finite time is guaranteed. In all cases, the exponential convergence rate, or the finite convergence time, can be quantitatively estimated on the basis of the parameters defining the neural network. As a by‐product, it is proved that the considered neural networks, although they are described by a system of differential equations with discontinuous right‐hand side, enjoy the property of uniqueness of the solution starting at a given initial condition. The results are proved by a generalized Lyapunov‐like approach and by using tools from the theory of differential equations with discontinuous right‐hand side. At the core of the approach is a basic lemma, which holds under the assumption of M‐matrices or H‐matrices, and enables to study the limiting behaviour of a suitably defined distance between any pair of solutions to the neural network. Copyright © 2006 John Wiley & Sons, Ltd.     

Synthesis and characterization of aniline copolymers containing carboxylic groups and their application as sensitizer and hole conductor in solar cells

Copolymers of m-aminobenzoic acid and o-anisidine doped with p-toluenesulphonic acid in different proportions were successfully synthesized by oxidative polymerization. The copolymers were characterized by FT-IR, UV–vis, ¹H NMR and EPR spectroscopies, cyclic voltammetry, conductivity and SEM. The copolymer with equivalent amounts of the monomers o-anisidine and m-aminobenzoic acid presented the highest conductivity, The EPR analyses and SEM images show that this copolymer provides more homogeneous films with particle size distribution of approximately 1–2 μm. The copolymer with a high fraction of o-anisidine gives rises to films with larger particle sizes and a more defined electrochemical process. The m-aminobenzoic acid monomer was intentionally chosen in order to promote a better electronic coupling between the conducting copolymer and the TiO₂ surface. The copolymers were tested as both sensitizers and hole conducting materials in dye-sensitized solar cells. The device assembled using the copolymer with the highest proportion of m-aminobenzoic acid units as sensitizer produced the highest photocurrent (I_sc = 0.254 mA cm^?2) and photovoltage (V_oc = 0.252 V) at 100 mW cm^?2. The energy diagram shows that although the electronic injection from the conducting polymer excited state is an allowed process the regeneration of the positive charges created after the electron transfer process is forbidden, thus explaining the low efficiency of solar energy conversion. When this copolymer was applied as a hole conducting material, an improvement in the V_oc to 0.4 V, was observed, indicating that this material is more suitable for charge transport when applied in this type of solar cells.