This work aims to build a reservoir computing system to recognize signals with the help of brainwaves as the input signals. The brainwave signals were acquired as the participants were listening to the signals. The human brain in this study can be regarded as the assistant neural networks or non-linear activation function to improve the signal recognition. We showed that within the brainwave frequency ranges from 14 to 16, 20, 30, and 32 Hz, the mean squared errors of the input signal recognition were lower than those without brainwaves. This result has demonstrated that the reservoir computing system with the help of human responses can obtain more precise results.

We propose and demonstrate a novel concept of a compact optical component aimed at transforming a point-like source into a Bessel beam. This component, called AXIGRIN, consists of an axicon fabricated at the end facet of a gradient index lens. It can be directly coupled to an optical fiber, a microscope objective, or vertical-external-cavity surface-emitting-laser to be used without preliminary adjustments, which is of practical interest for end users. This opens new avenues in domains, such as imaging, particle acceleration and manipulation, optical coherence tomography, data storage, laser cutting, etc. AXIGRIN also opens the perspective of using Bessel beams for endoscopy. The generation of linearly and radially polarized Bessel beams is demonstrated with a fiber AXIGRIN.

In radiobiology, low doses of high-LET radiation correspond to a few particle traversals through the cell population. Therefore, for studies on cell monolayers irradiated with a low dose of α-particles, it is extremely useful if the number and position of particle traversals can be determined. In this study we describe a new method, based on UV-curing, to obtain a 10μm thick CR-39 grafted onto a 2.5μm thick PolyEthylene Terephtalate (PET). This thin double polymeric layer, used as a dish base, has a regular and reproducible detector thickness which can be traversed by 3.5MeV α-particles, with a sufficient residual energy to traverse mammalian cells attached to the base. The recording properties of a PET-CR-39 dish, together with a demonstration of its use for radiobiological experiments, are presented. This new tool allows the precise determination of single-track impact parameters at a sub-cellular level.

The study of radiobiological effects induced in vitro by low fluences of alpha particles would be significantly enhanced if the precise localization of each particle track in the cell monolayer was known. From this perspective, we developed a new method based on tailor-made UV-radiation-cured CR-39, the production of which is described. Its validation both as a petri dish and as solid-state nuclear track detectors is demonstrated. With respect to the demands on solid-state nuclear track detectors in such experiments, these biologically compatible detectors have a controlled micrometric thickness that allows them to be crossed by the alpha particles. In this study, we present a method for obtaining 10-mum-thick CR-39, its chemical characterization, and its properties as a solid-state nuclear track detector under the environmental conditions of radiobiological experiments. The experimental studies performed with 3.5 MeV alpha particles show that their transmitted energy is sufficient enough to cross the entire cellular volume. Under optimal conditions, etched tracks are clearly defined 2 h after etching. Moreover, the UV-radiation-cured CR-39 represents an essentially zero background that is due to the short time between the production and use of the polymer. Under a confocal microscope, this thin solid-state nuclear track detector allows the precise localization of the impact parameter at the subcellular level.

Striae distensae are characterized by linear, smooth bands of atrophic-appearing skin that are reddish at first and finally white. They are due to stretching of the skin, as in rapid weight gain, or mechanical stress, as in weight lifting. The pathogenesis of striae distensae is unknown but probably relates to changes in the fibroblast phenotype. In order to characterize striae distensae fibroblasts, alpha-smooth muscle actin expression and contractile forces were studied. Five healthy women with early erythematous striae and five healthy women with older striae were selected. Paired biopsies were taken from the center of lesional striae and adjacent normal skin. Fibroblasts were obtained by an explant technique and expanded in vitro in Dulbecco’s modified Eagle‘s medium. Contractile forces generated by fibroblasts in collagen lattices were measured with the Glasbox device developed in our laboratory. Alpha-smooth muscle actin expression was studied by immunofluorescence labeling of cells and by flow cytometry. Fibroblasts from early striae distensae were the richest cells in alpha-smooth muscle actin filaments and generated the highest contractile forces. Their peak contractile force was 26% greater than normal fibroblasts. There was a 150% higher level of alpha-smooth muscle actin content in fibroblasts from early striae distensae compared with fibroblasts from normal skin. In contrast, there was no significant difference in force generation between old striae fibroblasts and normal fibroblasts with cells expressing no alpha-smooth muscle actin. The contractile properties of fibroblasts from striae distensae varies depending on the stage of the disease. In early striae distensae, fibroblasts acquire a more contractile phenotype, corresponding to that of myofibroblasts.

Cellular contraction, defined as the force cells exhibit on the extracellular matrix, plays a significant role in dermal tissue. To study the contractility of cells in vitro, we have developed a new patented device named GlaSbox ® “Growing Lattice Study Box”. It consists of a cell chamber composed with 8 rectangular wells (26 × 33 mM) in which lattices develop. Two opposite silicon beams hang down into each well. The lattice is attached to this sensor through a grid directly etched on the lower part of the beams. A strain gauge is deposited at the beam surface, and connected to form a Wheastone bridge. The strain gauges signal output is amplified then converted and collected by a computer which includes an acquisition card and a specific program giving directly the forces in real time. The significant advantages of the GlaSbox ® are: the absence of any interface between the collagen lattice and the beams which maintain it stretched, its ability to test eight lattices simultaneously, the low volumes of cells and collagen required. To demonstrate the applicability of this system, contractile forces of human fibroblasts from different skin conditions were measured such as chronic venous leg ulcers and striae distensae. These fibroblasts were found to produce an average force of 1.10 −8 N/cell and have greater contractile capacity than normal fibroblasts (Viennet et al., J Wound Care 2004, in press). The GlaSbox ® is a useful tool to study the contractility of dermis equivalent composed of various fibroblast lines and, the effect of different active principles or even growth factors (e.g., TGF‐β) on cellular contraction. In addition, it can be used to examine the relationship between cellular contraction, cell proliferation, and collagen production, which is important for the understanding of the mechanism of scar tissue formation.

BACKGROUND/AIMS:The aim of this paper is to propose an objective procedure for the evaluation of the skin aspect. This work is based on light scattering phenomena and in-vivo measurements of the skin profile and of the skin Bi-directional Reflection Distribution Function (BRDF). METHODS:We consider the basic mechanisms of light reflection and scattering by a surface to extract the key sur-face-parameters of aspect. It appears that the surface relief is determinant for the local surface orientation while the light scattering properties of the skin are responsible for the visibility of that skin relief. The first part presents the principles of skin-image formation on the retina and de-scribes the actual roles of the BRDF and of the skin relief. The second part is dedicated to experimental measurements on the skin in vivo. The 3D relief is reconstructed by a fringe projection method and numerical processing. The angular distribution of light reflected by the skin is also measured by means of a different set-up. RESULTS:The knowledge of both the skin relief obtained by 3D optical profilometry and the skin scattering behavior measured for regularly distributed set angle values, allows an objective aspect evaluation as well as a prediction of the skin images that an observer will receive. CONCLUSION:This paper presents both the principles and instrumentation elements suitable for the setting up of an objective evaluation procedure of the skin aspect.

OBJECTIVE:The tissue contraction phenomenon associated with wound healing is of prime importance for wound closure. Contractile properties of human fibroblasts from chronic venous leg ulcers were compared with those of normal fibroblasts using in vitro models.METHOD:Biopsies were taken from the uninvolved skin of the thigh, the epithelialised ulcer edge and the non-epithelialised ulcer centre in four patients (average age: 78 years). Fibroblasts were obtained by an explant technique and expanded in vitro in Dulbecco's Modified Eagle's Medium supplemented with 10% foetal calf serum and used for the assays at their fourth passage. Intracellular alpha-smooth muscle actin expression (alphaSM-actin) was studied by immunofluorescence labelling of cells cultured in monolayer. Contractile properties were evaluated using three-dimensional collagen lattices.RESULTS:Fibroblasts from the ulcer centre were the richest cells in actin filaments. Both populations of venous ulcer fibroblasts contracted more rapidly and to a greater extent than normal fibroblasts. The peak contractile forces developed by fibroblasts from the ulcer centre and the ulcer edge were 30% and 18% greater than normal fibroblasts respectively.CONCLUSION:Some functions of fibroblasts, in particular the generation of contractile forces and the formation of cytoplasmic actin filaments, seem not to be affected in chronic venous ulcers.DECLARATION OF INTEREST:This study was supported by the Fondation Coloplast pour la Qualite de la Vie of France.

In this paper we demonstrate a new method to attach cultures of collagen lattices on a silicon microdevice. First, we demonstrate the silicon biocompatibility feasibility and study, and then we describe a solution based on a specific grid directly etched on a 200 μm thick silicon plate. The collagen lattice can grow around this grid and attach the silicon plate during its development.

Laser ablation was applied to X-cut Z-propagation Ti:LiNbO3 waveguides. The effective refractive index change of the waveguides after the ablation was measured for both TE and TM modes, The change is more sensitive to the ablation for the TE than for the TM mode. This phenomenon was confirmed by measuring the modal effective refractive indices of a nonablated and an ablated planar Ti:LiNbO3 waveguide with the m-line method. A photoelastic effect that may cause the different effective index changes of the waveguide modes after ablation is discussed. (C) 2002 Society of Photo-Optical Instrumentation Engineers.

The coupling ratio of directional couplers in Z-cut Y-propagation and X-cut Z-propagation LiNbO3 crystals was adjusted by laser ablation. The coupling ratio change is more efficient for the TM-mode of Z-cut couplers. The method can be used to correct the uncertainty of the coupling ratio for directional couplers that occurs during fabrication process.

This paper describes in details the fabrication and tests of a micromechanical connector, which is used for the precise optical self-alignment of multi-waveguide optical integrated circuits (OIC) to ribbon optical fibers, without injecting light in the fiber. Nickel alignment pins are electrodeposited on the OIC using a photolithographic process, and these pins are inserted into suitable openings made on a silicon micromachined platform, on which optical fibers are accurately positioned using V-grooves. A simultaneous fabrication of several microstructures which are used as an assistance for the assembly of the fibers and the waveguides is presented for the first time. Design and fabrication issues are reported, as well as preliminary experimental results which show that excess optical losses on the order of 3dB per coupling facet can be obtained.

This paper describes the fabrication of a new mechanical microconnector, which is used for the precise optical self-alignment of multi-waveguide Optical Integrated Circuits (OIC) to ribbon optical fibers, without injecting light in the fiber. Nickel alignment pins are electrodeposited on the OIC using a photolithographic process, and the pins are inserted into suitable openings made on a silicon micromachined platform, on which optical fibers are accurately positioned using V-grooves. Design and fabrication issues are reported, as well as preliminary experimental results which show that excess optical losses on the order of 3 dB can be obtained