Characterization of the mechanism of interaction in ibuprofen-Eudragit RL100 coevaporates

The present study is a preliminary exploration of the affinity between a carboxylic model drug, the nonsteroidal antiinflammatory agent ibuprofen (IBU) and Eudragit RL100 (RL) polymer. Due to the presence of a variable amount of quaternary ammonium groups in this matrix, physical and chemical interaction with the carboxylic drug can occur, which reinforces its scant mechanical dispersion in the polymer network and can ultimately affect its release profile in vitro and in vivo. To study these aspects, IBU was mixed at increasing weight ratios and in different chemical forms (free acid, sodium salt, and n-butyl ester), to investigate further the role of the carboxylic group in the interaction with the RL polymer. Therefore, IBU-RL solid dispersions (coevaporates) were obtained and fully characterized in the solid state through spectroscopic, calorimetric, and x-ray diffractometric analyses. The in vitro release pattern of the drug, in the different chemical states, was studied for the coevaporates, compared with drug-RL physical mixtures, along with drug adsorption profiles from aqueous solutions on the surface of the polymer granules.     

Noninterferometric and nontomographic iterative method for field retrieval

A new method of field recovery is proposed based on the fact that an arbitrary light beam can be expressed as a finite sum over orthogonal field distributions with unknown coefficients. If these field distributions are eigenmodes of a specific waveguide, the coefficients of the field decomposition in orthogonal eigenmodes can be determined iteratively when the unknown field is passed through a series of waveguides that support an increasing number of modes. This series of waveguides can be replaced by a single reconfigurable electro-optic waveguide, which one can use to recover the unknown field by performing only intensity measurements.     

New technologies for relaxation: The role of presence.

In recent years, several publications have appeared on virtual reality (VR) therapy in the treatment of anxiety disorders. However, a limited number of these studies targeted stress management and relaxation. To evaluate the efficacy of VR as a support tool in the relaxation process, this study compared its efficacy with two other media (DVD and audiotape). The goals of the experiment were to test the efficacy of each condition in increasing relaxation and reducing anxiety, and whether the sense of presence-the feeling of being inside the media content-correlated with the efficacy of the treatment. Results suggested the importance of the sense of presence as a mediating variable between the media experience and the efficacy of the protocol. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An Optical Thermometer Exploiting Periodically Poled Lithium Niobate for Monitoring the Pantographs of High-Speed Trains

Optical thermometers have been widely investigated. Here, the temperature behavior of second harmonic generation (SHG) in periodically poled lithium niobate (PPLN) substrates is analyzed; indeed, the QPM tuning in PPLN devices and the obtained SHG efficiency depend on the crystal thermal expansion and dispersion, particularly in the case of guided propagation. Therefore, such devices are suitable to realize optical thermometers for demanding applications. This investigation originated with the request of a thermometer to be installed on the pantographs of high-speed trains. Therefore, it must be sturdy and reliable, but it has even to work in an EMD environment. The temperature behavior of the SHG was theoretically modeled and experimentally validated at 1550 nm, in both bulk propagation and APE channel waveguides. In the first case, by using a 10-mW source, which was obtained from a laser diode and a fiber amplifier, an accuracy of 0.3 degC was found. The pump power was about three orders of magnitude smaller in guided propagation. In view of testing on the trains, our investigation resulted in the design of a device without mechanical contacts with the input and output fibers. Since it works in free propagation, there are no serious alignment and packaging problems. The performances, which are expected to be the same of our tests, widely satisfy all the requirements for working effectively in a strongly hostile and EMD environment and for giving accurate measurements on a wide range of temperatures     

On‐Chip Magnetic Platform for Single‐Particle Manipulation with Integrated Electrical Feedback

Methods for the manipulation of single magnetic particles have become very interesting, in particular for in vitro biological studies. Most of these studies require an external microscope to provide the operator with feedback for controlling the particle motion, thus preventing the use of magnetic particles in high‐throughput experiments. In this paper, a simple and compact system with integrated electrical feedback is presented, implementing in the very same device both the manipulation and detection of the transit of single particles. The proposed platform is based on zig‐zag shaped magnetic nanostructures, where transverse magnetic domain walls are pinned at the corners and attract magnetic particles in suspension. By applying suitable external magnetic fields, the domain walls move to the nearest corner, thus causing the step by step displacement of the particles along the nanostructure. The very same structure is also employed for detecting the bead transit. Indeed, the presence of the magnetic particle in suspension over the domain wall affects the depinning field required for its displacement. This characteristic field can be monitored through anisotropic magnetoresistance measurements, thus implementing an integrated electrical feedback of the bead transit. In particular, the individual manipulation and detection of single 1‐μm sized beads is demonstrated.     

Performance analysis of parallel Schwarz preconditioners in the LES of turbulent channel flows

We present a comparative study of parallel Schwarz preconditioners in the solution of linear systems arising in a Large Eddy Simulation (LES) procedure for turbulent plane channel flows. This procedure applies a time-splitting technique to suitably filtered Navier–Stokes equations, in order to decouple the continuity and momentum equations, and uses a semi-implicit scheme for time integration and finite volumes for space discretisation. This approach requires the solution of four sparse linear systems at each time step, accounting for a large part of the overall simulation; hence the linear system solvers are a crucial component in the whole procedure. Several preconditioners are applied in the simulation of a reference test case for the LES community, using discretisation grids of different sizes, with the aim of analysing the effects of different algorithmic choices defining the preconditioners, and identifying the most effective ones for the selected problem. The preconditioners, coupled with the GMRES method, are run within SParC-LES, a recently developed LES code based on the PSBLAS and MLD2P4 libraries for parallel sparse matrix computations and preconditioning.     

Multiscale Corner Detection in Planar Shapes

This paper presents a multiscale corner detection method in planar shapes, which applies an undecimated Mexican hat wavelet decomposition of the angulation signal to identify significant points on a shape contour. The advantage of using this wavelet is that it is well suited for detecting singularities as corners and contours due to its excellent selectivity in position. Thus, this wavelet plays an important role in our approach because it identifies changes in non-stationary angulation signals, and it can be extended to multidimensional approaches in an efficient way when approximating this wavelet by difference of Gaussians. The proposed algorithm detects peaks on a correlation signal which is generated from different wavelet scales and retains relevant points on the decomposed angulation signal while discards poor information. Our approach assumes that only peaks which persist through several scales correspond to corners. Furthermore, we introduce a novel procedure to tune parameters for the corner detection algorithms that corresponds to the best relation between Precision and Recall measures. This technique guides the parameter adjustment of the algorithms according to the image database and it improves their performance with regard to true corner detection. Concerning the performance assessment of the algorithms, we compare the proposed one to other corner detectors by using Precision and Recall measures which are based on ground-truth information. Tests were carried out using more than a hundred images from a non-homogenous database that contains noisy and non-noisy binary shapes.