Search

Introduction L’utilisation de l’isocinetisme, comme outil de reeducation, est largement developpee pour les patients cerebroleses. Des preuves existent concernant son efficacite pour le membre inferieur, mais les donnees concernant le membre superieur restent insuffisantes [1] . La reproductibilite de la mesure isocinetique de la force est globalement demontree pour les personnes saines [2] . Concernant les personnes cerebrolesees, elle est surtout demontree pour la force des membres inferieurs [3] . Les donnees concernant la reproductibilite de la mesure du membre superieur se developpent [4] , notamment pour le coude ; mais les donnees concernant la reproductibilite de l’evaluation des rotateurs d’epaule sont encore rares [5] . Une definition de parametres reproductibles pourrait permettre une meilleure prise en charge du membre superieur des patients cerebroleses. Materiel, population et methode L’objectif de l’etude est d’evaluer la reproductibilite des parametres isocinetiques mesurant la force de l’epaule dans une population de patients victimes d’accident vasculaire cerebral. Les criteres d’inclusion de la population etaient un âge superieur ou egal a 60 ans, ayant eu un AVC datant de plus de 15 jours, avec une motricite du membre superieur superieure ou egale a 3 sur l’echelle de Held-Pierrot-Desseilligny. Pour etablir les mesures de force des rotateurs mediaux et lateraux d’epaule, la position assise semblait etre la plus interessante. Cette position, assise, abduction a 45°, axe humeral dans le plan scapulaire, offrirait la meilleure alternative entre confort et resultat pour l’evaluation des rotateurs internes et externes de l’articulation scapulo-humerale [2] , [6] , [7] . Le pic de couple et le travail total, ainsi que leur coefficient de variation reciproque, ont ete evalues en concentrique (240 et 60°/s) et excentrique (30 et 120°/s) sur les deux groupes musculaires. Resultats Les resultats montrent une forte correlation des evaluations intra-observateurs dans 12 des 16 parametres mesures (ICC 0,76–0,93) ; la reproductibilite inter-observateurs est egalement forte dans 11 des 16 parametres mesures (ICC 0,82–0,96). Conclusion ou discussion Des parametres ressortent comme positifs concernant la reproductibilite inter et intra-observateurs, particulierement dans l’evaluation de la force en concentrique, a vitesse lente ; cela semble plus discutable a vitesse rapide, notamment sur le mode excentrique. Il faut toutefois relativiser ces resultats quant a l’echantillonnage et a l’heterogeneite du groupe.

Novel lithium metal polymer solid state batteries with nano CLiFePO4 , nano Li1.2V3O8 counter-electrodes (average particle size 200 nm) and NMC were studied for the first time by in situ SEM and impedance during cycling. The kinetics of Li-motion during cycling is analyzed self-consistently together with the electrochemical properties. We show that the cycling life of the nano Li1.2V3O8 is limited by the dissolution of the vanadium in the electrolyte, which explains the choice of nano C-LiFePO4 (1300 cycles at 100% DOD): with this olivine, no dissolution is observed. In combination with lithium metal, at high loading and with a stable SEI an ultrahigh energy density battery was thus newly developed in our laboratory. The electrochemical of new polymer with high voltage with NMC cathode material will show during this presentation. The commercial use of lithium metal batteries was delayed because of dendrite formation on the surface of the lithium electrode, and the difficulty finding a suitable electrolyte that has both the mechanical strength and ionic conductivity required for solid electrolytes. Recently, strategies have developed to overcome these difficulties, so that these batteries are currently an option for different applications, including electric cars. In this work, we review these strategies, and discuss the different routes that are promising for progress in the near future. We will explain the Gen 2 solid state lithium metal battery technology: from the laboratory to commercialization.

We report in-plane resistivity and elastic constant C33 measurements on the Na0.8CoO2 and Na0.5CoO2 systems. An ordering transition is found at T0=280 K for Na0.8CoO2. The temperature dependence of the elastic constant C33 propagating perpendicular to the CoO2 layers is interpreted, in a phenomenological approach, as being due to the anharmonicity of atomic vibrations. The effective Gruneisen parameter γeff deduced directly from the temperature dependence of C33 exhibits important changes at the charge ordering, magnetic and metal-insulator phase transitions.

A theoretical study of the write, read, and erase processes in electrical scanning probe storage on phase-change media is presented. Electrical, thermal, and phase-transformation mechanisms are considered to produce a physically realistic description of this new approach to ultrahigh-density data storage. Models developed are applied to the design of a suitable storage layer stack with the necessary electrical, thermal, and tribological properties to support recorded bits of nanometric scale. The detailed structure of nanoscale crystalline and amorphous bits is also predicted. For an optimized trilayer stack comprising Ge/sub 2/Sb/sub 2/Te/sub 5/ sandwiched by amorphous or diamond-like carbon layers, crystalline bits were roughly trapezoidal in shape while amorphous bits were semi-ellipsoidal. In both cases, the energy required to write individual bits was very low (of the order of a few hundred picoJoules). Amorphous marks could be directly overwritten (erased), but crystalline bits could not. Readout performance was investigated by calculating the readout current as the tip scanned over isolated bits and bit patterns of increasing density. The highest readout contrast was generated by isolated crystalline bits in an amorphous matrix, but the narrowest readout pulses arose from isolated amorphous marks in a crystalline background. To assess the ultimate density capability of electrical probe recording the role of write-induced intersymbol interference and the thermodynamic stability of nanoscale marks were also studied.

L’approche dans les pathologies neurologiques centrales, et notamment dans la sclerose en plaques, a longtemps ete de deconseiller le renforcement musculaire. Pourtant le deficitmusculaire est une composante importante du handicap, particulierement des troubles de la marche. Les dynamometres isocinetiques permettent une quantification precise du deficit musculaire et ainsi la mise en place de protocole de renforcement musculaire specifique, notamment en isocinetisme. Dans cet article, nous presentons une synthese des protocoles d’evaluation isocinetique et l’apport des techniques de renforcement musculaire dans la sclerose en plaques.

Mixing molten salts with luminescent conjugated polymers provides the ability to lower the current threshold of organic electroluminescence (EL) devices. However, this process generally results in unwanted premature electrical aging. We used dynamic atomic force microscopy (AFM) in the electric force detection regime to study the phase microseparation occurring in the salt-polymer blend. We found that in the spin-coated layers, the molten salt most often forms discotic, roughly self-organized sub-microdomains. Their size and density strongly depend on the polymer side chains and overall molecular weight, on the molten salt nature, and on their respective concentrations in solution. We show that the diode current is injected into the vicinity of the interface between the salt and polymer domains, since it is proportional to the perimeter of the salt domains per surface unit, as estimated from the AFM images. The electrical aging is attributed to the degradation of the interface between the polymer and salt...

Chloride residues on the surface of fuel cell catalysts are known to decrease the catalytic activity, especially for O2 reduction. Using Armand's ligand, which contains the chloride free DCTA anion, for the colloidal stabilisation of nanoscopic Pt and PtRu catalysts precursors (

Due to their high ecological and patrimonial value Festuca eskia and Nardus stricta meadows and Rhododendron ferrugineum heathlands need to be locally preserved in the Pyrenees. This could pose dilemmas to conservation managers if heathlands invade and replace the meadows. However, studies showing that the heathlands do actually invade meadows are lacking in the Pyrenees and the invasion hypothesis therefore remains to be proved. So, vegetation pattern changes in a particularly vulnerable site from the central Pyrenees was investigated by two means: (i) interpretation of stereo pairs of aerial photographs and (ii) analysis of the demography of Rhododendron populations in ten 150 m 2 experimental plots. The main results from photo interpretation indicated that, during the period between 1954 and 1995, 15% of a 17 ha meadow area shifted to heathland. This corresponded with a 592 m 2 year −1 colonization rate and to an overall front progression of heathland over meadows of 3–60 m. Demographic data showed that meadow colonization by heathland passed through successive phases but appeared to be a rather slow process that can take as long as 120–320 years. During the process the cover rate over the 150 m 2 plots varied between 1 and 0.4 m 2 year −1 . Heathland extension does not seem to have been favored by the decrease in grazing pressure. Despite this, the progression of heathlands over meadows seems endangering the meadows. Finally we propose practices locally to limit the progression of Rhododendron.

Optical data storage is advancing rapidly as we move forward in the 21st Century. Most people today are familiar with CDR and CD-RW as forms of optical data storage, but DVD-R, with considerably higher capacity, will challenge CD-R as the preferred storage medium soon. This review paper looks at the current state of optical recording and some of the current techniques which offer increased magneto-optical storage density, such as Magnetic Super Resolution (MSR), which is already on the market as the GIGAMO disk, and other methods under development. The latter includes Magnetically AMplified Magneto-Optical System (MAMMOS) and Domain Wall Displacement Detection (DWDD). To complement these technologies are a variety of optical techniques, such as near-field recording, which will enable higher storage densities by overcoming the diffraction limit. Holographic storage has promised much over the years, and has largely remained in the research domain. However, new materials and multiplexing techniques show considerable promise for this volumetric storage medium. The overlapping optical and magneto-optical technologies have yielded the concept of hybrid recording and this will also be addressed in this paper. The paper concludes with a look at alternative storage mechanisms, which utilise electronic, as opposed to thermal transitions, to offer improved data rates and improved storage efficiency, and this may dramatically change the way data is stored.

We have studied the well known spectral shift of polyfluorene blue light emitters, using either electrochemical cells or conventional organic light emitting diodes. From the recording of the electroluminescence spectra as a function of “stress” time, we conclude that the degradation mainly depends on the number of electrons which have passed through the conducting polymer, rather than on the hole current magnitude or the dissipated power.

Novel lithium metal polymer solid state batteries with nano C-LiFePO4 and nano Li1.2V3O8 counter-electrodes (average particle size 200 nm) were studied for the first time by in situ SEM and impedance during cycling. The kinetics of Li-motion during cycling is analyzed self-consistently together with the electrochemical properties. We show that the cycling life of the nano Li1.2V3O8 is limited by the dissolution of the vanadium in the electrolyte, which explains the choice of nano C-LiFePO4 (1300 cycles at 100% DOD): with this olivine, no dissolution is observed. In combination with lithium metal, at high loading and with a stable SEI an ultrahigh energy density battery was thus newly developed in our laboratory.

Rockfall susceptibility evaluation of slopes overhanging roads is one of the key elements in road network risk analysis. A new Rockfall Susceptibility Index (Ro.S.I.) was developed for the Autonomous Region of Aosta Valley road network to be used as a part of the ROckfall risk MAnagement (RO.MA.) method. This index takes into account several parameters and has been specifically designed for mountainous areas; it allows a fast analysis at regional scale and can be a useful tool for road managers and other public administrators. This paper illustrates the necessity of this new index and describes the considered parameters as well as the reasons of their selection.

We present a systematic analysis of the current transients accompanying the formation of the electrode–electrolyte double layers in organic light-emitting electrochemical cells. By using various room-temperature molten salts, conducting polymers, and electrodes, we show that the current I always decreases as a power law of time, I∝t−n. The current transients are formed of various time domains, each one being characterized by a power-law exponent n

In order to achieve higher areal density for optical recording, multilayered magneto optical structures, working at shorter wavelength and higher numerical aperture than the DVD are being developed over the world. MSR (Magnetic Super Resolution) and MAMMOS (Magnetic AMplifying Magneto Optical System) structures use magnetic couplings between magnetic layers and need a very fine temperature control of the recording, switching and reading layers. It has been shown that the power margin for MAMMOS reading is very small. At numerical apertures of NA=0.85 with far field optics and even at higher apertures with the Solid Immersion Lens (SIL), it is essential to determine the spatial distribution of the electric field at the focal point of the objective as well as in the different recording layers. We will present a vector simulation of the electromagnetic field in a MO structure illuminated by a high NA focused field, and discuss absorption in the thin films. The MO properties in the different layers are also calculated at variable incidence angles. We illustrate this with SIL coupling calculations.

n/a

The electrochemical behavior of three triphylite (LiFePO4) ores from different mining localities has been investigated. Two of them show clearly an activity corresponding to the triphylite phase. A discharge capacity of 85 mAh g−1 was obtained. The benefit of heat treatment that allows to deposit the electronically conductive carbon-based coating on the particles is reported for both natural and synthetic LiFePO4 samples. Discharge capacity, kinetics and stability upon cycling were all improved after the heating process. The best results were obtained with carbon coatings coming from the decomposition of a modified polycyclic aromatic. In this case, for synthetic samples, the whole capacity was reversibly exchanged and less than 1% of the initial capacity was lost after 10 cycles.

In this letter, we present a study on the electrical behavior of phase-change memories (PCMs) based on a GeTe active material. GeTe PCMs show, first, extremely rapid SET operation (yielding a gain of more than one decade in energy per bit with respect to standard GST PCMs), second, robust cycling, up to 1 × 105, with 30-ns SET and RESET stress time, and third, a better retention behavior at high temperature with respect to GST PCMs. These results, obtained on single cells, suggest GeTe as a promising alternative material to standard GST to improve PCM performance and reliability.

In this study the authors investigate possible objectives that the central nervous system (CNS) may consider in planning a strategy for stepping over an obstacle. A link segment simulation model has been developed based on Lagrangian dynamics, with which muscle force inputs can be optimized to best satisfy the postulated objectives for landing stability, obstacle clearance, and efficiency of the movement. A direct optimization approach with multiobjective criteria based on the kinematic and kinetic characteristics of the swing phase of locomotion is used in the simulation. The role of initial conditions at toe-off and biarticular muscle forces during the swing phase was also investigated. The optimization was performed for both leading limb and the trailing limb during the swing phase. The simulation results demonstrate that the use of biarticular muscles is sufficient to clear a range of obstacles with the trailing limb (obstacle encountered during early swing). Stride length or landing stability objectives need not be specified suggesting a simpler control of trailing limb trajectory by the CNS (one of stride length or landing stability objectives were not necessary). In contrast while the use of biarticular muscles can be sufficient to clear obstacles with the leading limb (obstacle encountered during mid to late swing), a stable landing and smooth toe and knee trajectories are compromised without suitable initial conditions at toe-off. The results suggest that the set of postulated objectives for the lead limb is adequate, although not complete.

The electrochemistry of polymers is reviewed, in comparison with solid or liquid electrolytes. It is shown that the coordination chemistry leading to the formation of conductive complexes is very general with specific interactions (e.g. transition metal-nitrogen). While the transference numbers are still the subject of controversies, a coordination chemistry akin to that of water for PEO or ammonia with PEI exists. Also, the possibility of redox conduction, through microphase separation leads to mixed conductivity (ions + electrons).

Room temperature molten salt systems based on methyl-hexyl-imidazolium iodide (MHImI) have been used to scrutinize the performance characteristics, the stability and the mass-transfer effects in a photoelectrochemical regenerative device, as the latter is influenced and can even be limited by local concentration and mass-transport of the electroactive redox mediator species in the electrolyte phase. These salts appear to afford particular advantages over organic liquids as solvents for solar cell electrolytes. Cell performance showed outstanding stability, with an estimated sensitizer turnover in excess of 50 million. An investigation has been carried out on the physical-electrochemical properties of MHImI and its mixtures with organic solvents such as n-methyl-oxazolidinone, acetonitrile and with other lower viscosity molten salts such as methyl-butyl-imidazolium triflate. The repercussions of these properties on solar cells is described experimentally by the performance of practical application devices. Simulation models of mass transport in the nanocrystalline solar cell help illustrate operational aspects such as concentration profiles, limiting currents, anticipated mass-transfer overpotential as a function of current density, and they help to make projections as to how the properties of molten salt electrolytes can be better exploited toward this practical end.

A new family of redox-active polymers have been obtained by polycondensation of α,ω-diamino oligopolyethers with various aromatic tetracarboxylic acid anhydrides. The polyether blocks retain the usual cation co-ordination ability leading to solid-state ionic conduction while the relatively large electron affinity of the bis-imide moieties formed in the block polymers allows the reversible formation of stable radical anions (• − and •• 2− ) in the range 2–2.6 V vs. Li°. Either slow-scan or microelectrode voltammetry indicate that the totality of the redox centres in such materials are readily accessible for all polyether spacer lengths tested (6–22 ether fragments), suggesting both a fast electron-exchange mechanism between anion radicals and a tendency for self assembly (stacking) of the planar aromatic groups. When increasing the number of atoms in the aromatic ring, the peak separation became smaller (benzene > naphthalene > perylene), resulting ultimately in simultaneous 2-electrons injection. These materials, due to the high coloration efficiency of the reduced state and their ready processability in thin films are excellent candidate for the realisation of laminated solid-state electrochromic devices.

The physical properties of the ionic conductor, obtained by dissolution of lithium trifluoromethanesulphonylimide in polyethylene oxide, (PEO)nLi+((CF3SO2)2N)- have been investigated for several values of n. The phase diagram has been established from both DSC and NMR techniques. The diffusion coefficients of 7Li and 19F containing Species, determined by the pulsed magnetic field gradient (PMFG) technique, are interpreted as the measures of the cationic and anionic transport numbers, which are concentration dependent, and t+ reaches a value close to 0.3. This study is complemented by a systematic analysis of the behaviour of the 7Li relaxation time T1 versus temperature and concentration which is correlated to the glass temperature Tg.