Comparison of gait between young adults fitted with the space foot and nondisabled persons

Prosthetic feet having new keel configurations were specially designed to store deformation energy during early and midstance and release it at push-off. These prosthetic components display longitudinal symmetry favoring good energy storage/release capability in the sagittal plane. The need for inverters/everters either as independent components or within the foot structure has long been recognized. This article documents the walking and slow jogging performances of six young adults wearing below-knee prostheses fitted with the Space Foot, a flexible foot prosthesis that provides medio-lateral control at heel-strike and lateral and forward propulsion at push-off. Results indicate that the Space Foot behaves as a flexible keel foot prosthesis. Its gait performances are also good for fast walking; however, the Space Foot's actual design should be modified if used in sporting activities involving running.     

Physiological and biochemical markers in the process of resistance and/or tolerance of heavy metals in the abandoned mining area of Sidi Kamber,Skikda, Algeria

This paper reports the biomonitoring of metallic pollution in the mine of Sidi Kamber Skikda town, to determine the resistance and/or tolerance to Zn, Pb, Cd and Cu in metalliferous plants. During the period of March–May, 2015, soil and plants samples were collected from three different stations in the study area. The total heavy metal fraction was determined by ICP/MS, whereas biochemical markers were determined by spectrophotometric techniques. The results obtained showed high levels of heavy metals in soil and plants compared to international standards. The translocation factor revealed that the studied plants can transfer and/or accumulate metals in their roots or their aerial parts as a function of characteristics of each metal, soil contents and physiological role in the plant. The contents of chlorophyll, proline, total sugars and total proteins are directly influenced by changes in bioavailable contents of heavy metals. It has been found that the plants studied and biomarkers are better suited for phytoremediation and biomonitoring of heavy metals pollution.     

Kinematic modeling for the assessment of wheelchair user'sstability

A computer kinematic model was developed to simulate the lateral and transverse stabilities of wheelchair users in order to compare the effect of different backrests. This model is composed of ellipsoids and parallelepipeds representing the main components of the human body, the seating devices and the wheelchair. A fifteen-segment three-dimensional (3-D) model linked by spherical and revolute joints was created using the ADAMS software (Mechanical Dynamics, Inc.). Torsional springs and dampers are used at the joints to represent four sets of articulation stiffness. Seating devices are represented with 45 rectangular surface patches. The interface between human body and seating devices is modeled by contact elements, which included the specification of stiffness, damping, and deformation of cushions and buttocks. Simulations of a user and his wheelchair moving at 1.4 m/s on a tilted pathway were performed. Different indexes [trunk lateral tilt (TLT) and trunk transverse rotation (TTR)] were measured and compared to those of a similar experimental study on four subjects. The effect of joint stiffness was quantified and a sensitivity study showed the importance of the hip, neck, lumbar, and thoracic joint stiffness on model response (between 16% and 68%). Two backrests (standard and highly contoured) were tested with the kinematic model and their stability compared. Overall, the coherence between the simulations and the experiments shows that this approach is appropriate to compare various seating devices (maximal difference of 1.3° between the simulated and experimental curves for the intermediate joint stiffness sets). The smallest rotations of the highly contoured backrest (6.3° versus 8.9° for TLT and 3.9° versus 6.7° for TTR) suggest that the contouring of the mid torso is more efficient than the lower torso to provide stability to the wheelchair user. This model is an adequate tool to test and improve the design of seating aids     

Biomechanical analysis of legrest support of occupied wheelchairs: comparison between a conventional and a compensatory legrest.

This study was undertaken to investigate the effects of elevating legrest on posture and pressure distribution in a group of ten able-bodied subjects sitting in a manual wheelchair. Two types of legrest were tested: a conventional elevating legrest with a fixed axis of rotation, and a compensatory elevating legrest with a moving axis of rotation. A three-dimensional (3-D) kinematics analysis was carried out to assess body posture simultaneously with pressure measurement data collected at the back, seat, calf and foot supports. The compensatory legrest enables to lengthen foot support as the legrest proclines. This compensation at the knee joint level has a beneficial effect in minimizing pelvic and thigh motion as well as in reducing pressure distribution under seat and foot supports. In contrast, the use of a conventional legrest modifies significantly the subject's posture and induces a substantial increase of 40% on pressure data under ischial tuberosities in procline position. These findings are important for disabled and elderly people who need to elevate their lower leg frequently.     

Adaptive pseudo-noise code acquisition scheme using automatic censoring for DS/SS communication in frequency-selective Rayleigh fading channel

An adaptive pseudo-noise code acquisition scheme based on automatic multipath signal cancellation for mobile communication systems in frequency-selective Rayleigh fading channel is proposed. The proposed system combines a serial strategy and an automatic censored cell-averaging constant false alarm rate (CFAR) detector based on ordered data variability. This system does not require any a priori information about the number of interferences caused by the presence of multipath signals in the reference channel. The mean acquisition time and the detection performances of the proposed processor are evaluated and compared with those of the conventional adaptive acquisition scheme based on fixed-censoring point detector. It is shown that the considered scheme outperforms significantly the conventional one. The effects of various channel parameters on the acquisition performance, namely the number of resolvable paths, the partial correlation length and the signal-to-noise ratio are also investigated.     

Energy Efficiency Optimization for Wireless Body Area Networks Under 802.15.6 Standard

Wireless Personal Communications - With the attractive applications in e-Health, a booming interest is granted to wireless body area network (WBAN). Through WBAN, healthcare professionals can...     

Contribution study of properties of copper indium diselenide thin films

Stoichiometric powder of CuInSe₂ (CIS) was prepared from molten stoichiometric quantities of the elements. The structure analyzed by X-ray diffraction powder (XRD), shows mainly the chalcopyrite phase. CIS polycrystalline thin films deposited from this powder have been grown on glass substrates in vacuum by thermal evaporation method. The structural and electrical properties of both as-deposited and annealed films were studied using X-ray diffraction and dark conductivity measurements respectively. As-prepared films at room temperature showed an amorphous structure. However, the chalcopyrite structure with (112) preferential orientation was observed after annealing in vacuum at 400 °C during 30 min. The influence of the annealing process on the dark conductivity of the films was also discussed.     

Study of the properties of CuInSe2 materials prepared from nanoparticle powder

This work studies the properties of CuInSe₂ (CIS) thin films obtained from nanoparticle powder. The samples were prepared by direct thermal evaporation of ball milled powder from a tungsten crucible onto precleaned glass substrates, using a BALZERS coating unit. The as deposited films were annealed in a vacuum at different temperatures. The composition, structure, morphology and optical properties of these samples have been investigated. X-ray diffraction (XRD) results showed that the CuInSe₂ phase may be prepared by mechanical alloying method. The crystallites of the CIS powder were found to be partially copper-rich. The as-deposited film was polycrystalline in nature having chalcopyrite structure as a mainly phase. The surface morphology is homogeneous across the surface. Expected optical properties (E_g = 1.04 eV, α ≈ 10⁴ cm^? 1) and near stoichiometric composition (Cu: 23.62 at.%, In: 24.35 at.% and Se: 52.03 at.%) were determined.     

Simultaneous estimation of the path,magnitude and orientation of the femorotibial contact forces using bone geometry constraints: an exploratory numerical study for the stance phase of gait

The present study introduced a new method to simultaneously optimize the path, magnitude and orientation of medial and lateral femorotibial contact forces using bone geometry constraints. The new method will be numerically compared to the known contact point method while estimating the muscle and contact forces for the stance phase of a single gait trial.A single generic lower extremity model was modified to allow knee flexion with an instantaneous rotation center. The contact point method simulated medial and lateral contact forces with no limited magnitude and with predefined one-dimensional paths and orientations. The new contact zone method simulated contact forces with a limited magnitude and with two-dimensional paths and orientations constrained by the geometry of the bones. A high and low limit was used to study the effect of limiting the contact force magnitude on the predicted forces.The paths of the contact forces for the contact zone method showed a difference up to 25.5 mm with respect to the contact point model. The contact zone method also allowed for more shear contact forces and for some modulation of the external frontal moment. Further limiting the contact force magnitude induced noticeable differences of muscle forces.The contact zone method allows the path, magnitude and orientation of the femorotibial contact forces to be sensitive to knee bone geometries and to the amount of allowable joint contact force. Such a method is promising in characterizing the contact forces with modified gait, bone geometries and knee strength associated with pathological conditions such as osteoarthritic and ACL-deficiency.     

Rapid and accurate face depth estimation in passive stereo systems

In this paper, we introduce a novel approach for face depth estimation in a passive stereo vision system. Our approach is based on rapid generation of facial disparity maps, requiring neither expensive devices nor generic face models. It consists in incorporating face properties into the disparity estimation process to enhance the 3D face reconstruction. We propose a model-based method that is independent from the specific stereo algorithm used. Our method is a two-step process. First, an algorithm based on the Active Shape Model (ASM) is proposed to acquire a disparity model specific to the face concerned. Second, using this model as a guidance, the dense disparity is calculated and the depth map is estimated. Besides, an original post-processing algorithm is proposed in order to detect holes and spikes in the generated depth maps caused by wrong matches and uncertainties. It is based on the smoothness property of the face and a local and global analysis of the image. Experimental results are presented to demonstrate the reconstruction accuracy and the speed of the proposed method.