Feature extraction of the first difference of EMG time series for EMG pattern recognition

This paper demonstrates the utility of a differencing technique to transform surface EMG signals measured during both static and dynamic contractions such that they become more stationary. The technique was evaluated by three stationarity tests consisting of the variation of two statistical properties, i.e., mean and standard deviation, and the reverse arrangements test. As a result of the proposed technique, the first difference of EMG time series became more stationary compared to the original measured signal. Based on this finding, the performance of time-domain features extracted from raw and transformed EMG was investigated via an EMG classification problem (i.e., eight dynamic motions and four EMG channels) on data from 18 subjects. The results show that the classification accuracies of all features extracted from the transformed signals were higher than features extracted from the original signals for six different classifiers including quadratic discriminant analysis. On average, the proposed differencing technique improved classification accuracies by 2–8%.     

NH_3 Plasma Surface Treatments of Engineering Fluoropolymers: A Way to Enhance Adhesion of Ni or Cu Thin Films Deposited by Electroless Plating

FLUOROPOLYMERS(FPs)are thermoplasticmaterials which exhibit a number of unique chemicaland physical characteristics that no other man-madeplastic product gets together.For example,FPs showvery good resistance to almost all chemicals,excellentwater vapor barrier properties,high thermal stability,outstanding electrical insulation properties(lowdielectric constant and dissipation factors),extremelylow frictional coefficient giving them high auto-lubrication properties,high resistance to rad…     

Motion study of the hip joint in extreme postures

Many causes can be at the origin of hip osteoarthritis (e.g., cam/pincer impingements), but the exact pathogenesis for idiopathic osteoarthritis has not yet been clearly delineated. The aim of the present work is to analyze the consequences of repetitive extreme hip motion on the labrum cartilage. Our hypothesis is that extreme movements can induce excessive labral deformations and lead to early arthritis. To verify this hypothesis, an optical motion capture system is used to estimate the kinematics of patient-specific hip joint, while soft tissue artifacts are reduced with an effective correction method. Subsequently, a physical simulation system is used during motion to compute accurate labral deformations and to assess the global pressure of the labrum, as well as any local pressure excess that may be physiologically damageable. Results show that peak contact pressures occur at extreme hip flexion/abduction and that the pressure distribution corresponds with radiologically observed damage zones in the labrum.

Robust pose estimation and recognition using non-gaussian modeling of appearance subspaces

We present an original appearance model that generalizes the usual Gaussian visual subspace model to non-Gaussian and nonparametric distributions. It can be useful for the modeling and recognition of images under difficult conditions such as large occlusions and cluttered backgrounds. Inference under the model is efficiently solved using the mean shift algorithm     

Using retina modelling to characterize blinking: comparison between EOG and video analysis

A large number of car crashes are caused by drowsiness every year. The analysis of eye blinks provides reliable information about drowsiness. This paper proposes to study the relation between electrooculogram (EOG) and video analysis for blink detection and characterization. An original method to detect and characterize blinks from a video analysis is presented here. The method uses different filters based on the human retina modelling. A illumination robust filter is first used to normalize illumination variations of the video input. Then, Outer and an Inner Plexiform Layer filters are used to extract energy signals from eye area. The eye detection is processed mixing gradient and projection methods which makes it able to detect even closed eyes. The illumination robust filter makes it possible to detect the eyes even in night conditions, without using external lighting. The video analysis extracts two signals from the eye area measuring the quantity of static edges and moving edges. Blinks are then detected and characterized from these two signals. A comparison between the features extracted from the EOG and the same features extracted from the video analysis is then performed on a database of 14 different people. This study shows that some blink features extracted from the video are highly correlated with their EOG equivalent: the duration, the duration at 50%, the frequency, the percentage of eye closure at 80% and the amplitude velocity ratio. The frame rate influence on the accuracy of the different features extracted is also studied and enlightens on the need of a high frame rate camera to detect and characterize accurately blinks from a video analysis.     

Functionalization of Polymer Surfaces Using Excimer VUV Systems and Silent Discharges. Application to Electroless Metallization

New approaches for electroless plating of nonconductive polymers or polymer-based materials are described. In this work, polyimide substrates were surface-functionalized (i) in nitrogenated (ammonia at reduced pressure) and oxygenated (air at atmospheric pressure) atmospheres under assistance of vacuum-ultraviolet (VUV) irradiation (use of a xenon silent discharge excimer source) or (ii) directly in air at atmospheric pressure using a dielectric-barrier discharge (DBD) device. After functionalization, the substrates were “activated” by dipping in a dilute acidic PdCl₂ solution or by spin-coating of a thin metal-organic film (from a solution of palladium acetate (PdAc) in chloroform). The catalytic activity of the so-deposited palladium species toward the electroless deposition of nickel was studied before and after a VUV post-irradiation (in air at atmospheric or reduced pressure) with a view to understanding better the role of the reducer (sodium hypophosphite) within the electroless bath.

This work confirms the specific interest of grafting nitrogenated functionalities onto polymer surfaces for attaching covalently the palladium-based catalyst (in particular in the case of the PdCl₂ route), forming thus strong Pd - N - C bonds at the metal/polymer interface. This results from the strong chemical affinity of palladium toward nitrogen. On the other hand, when oxygenated functionalities are surface-grafted, the conventional two-step procedure using SnCl₂ and PdCl₂ solutions can be proposed due to the strong chemical affinity of tin toward oxygen. The Ni deposits obtained under these different conditions pass the standard Scotch^®-tape test and, therefore, exhibit a good practical adhesion. For this same purpose, it is interesting to note that the DBD treatment operating in air at atmospheric pressure causes an increase of the surface roughness and, therefore, an improvement in adhesion of metallic films when their initiation is catalyzed through the PdAc route. In addition, this work demonstrates that extensive research still has to be performed to understand and improve the Ni/polymer adhesion when the PdAc route associated with a VUV irradiation is considered.     

ASGPR‐Mediated Uptake of Multivalent Glycoconjugates for Drug Delivery in Hepatocytes

Liver cells are an essential target for drug delivery in many diseases. The hepatocytes express the asialoglycoprotein receptor (ASGPR), which promotes specific uptake by means of N‐acetylgalactosamine (GalNAc) recognition. In this work, we designed two different chemical architectures to treat Wilson's disease by intracellular copper chelation. Two glycoconjugates functionalized with three or four GalNAc units each were shown to enter hepatic cells and chelate copper. Here, we studied two series of compounds derived from these glycoconjugates to find key parameters for the targeting of human hepatocytes. Efficient cellular uptake was demonstrated by flow cytometry using HepG2 human heptic cells that express the human oligomeric ASGPR. Dissociation constants in the nanomolar range showed efficient multivalent interactions with the receptor. Both architectures were therefore concluded to be able to compete with endogeneous asialoglycoproteins and serve as good vehicles for drug delivery in hepatocytes.     

Adhesion Science and Surface Analysis. Typical Examples

A number of surface modification methods using mechanical, chemical, electrochemical or physical processes have commonly been employed to treat adherend surfaces and improve adhesion in various bi- or multi-layered systems which play a key role in many advanced technologies. Results reported in this review paper deal more particularly with components of polymer-metal systems and provide typical examples of surface analysis obtained by x-ray photoelectron spectrometry (XPS), ion scattering spectrometry (ISS), low-energy electron induced x-ray spectrometry (LEEIXS), optically stimulated electron emission (OSEE) and Fourier transform infra-red spectrometry (FTIR). These examples concern, on the one hand, metallic adherends (aluminum, stainless steel, zinc-coated steel, gold) the surfaces of which were modified by cleaning, etching, oxidation, conversion or chemical grafting and, on the other hand, bonded joints (polyester-steel and epoxy-aluminum systems) which were delaminated using a peel test and a three-point flexure test, respectively.