Modulation of spinal excitability following neuromuscular electrical stimulation superimposed to voluntary contraction

Purpose. Neuromuscular electrical stimulation (NMES) superimposed on voluntary muscle contraction has been recently shown as an innovative training modality within sport and rehabilitation, but its effects on the neuromuscular system are still unclear. The aim of this study was to investigate acute responses in spinal excitability, as measured by the Hoffmann (H) reflex, and in maximal voluntary contraction (MVIC) following NMES superimposed to voluntary isometric contractions (NMES+ISO) compared to passive NMES only and to voluntary isometric contractions only (ISO). Method. Fifteen young adults were required to maintain an ankle plantar-flexor torque of 20% MVC for 20 repetitions during each experimental condition (NMES+ISO, NMES and ISO). Surface electromyography was used to record peak-to-peak Hreflex and motor waves following percutaneous stimulation of the posterior tibial nerve in the dominant limb. An isokinetic dynamometer was used to assess maximal voluntary contraction output of the ankle plantar flexor muscles. Results. H-reflex amplitude was increased by 4.5% after the NMES+ISO condition (p < 0.05), while passive NMES and ISO conditions showed a decrease by 7.8% (p < 0.05) and no change in reflex responses, respectively. There was no change in amplitude of maximal motor wave and in MVIC torque during each experimental condition. Conclusion. The reported facilitation of spinal excitability following NMES+ISO could be due to a combination of greater motor neuronal and corticospinal excitability, thus suggesting that NMES superimposed onto isometric voluntary contractions may provide a more effective neuromuscular stimulus and, hence, training modality compared to NMES alone

Specification and automatic checking of architecture constraints on object oriented programs

International audienceContext: Architecture constraints are specifications of conditions to which an architecture model must adhere in order to satisfy an architecture decision imposed by a given design principle. These constraints can be specified with predicate languages like OCL at design time and checked on design artifacts. Objective: Many works in the literature studied the importance of checking these constraints to guarantee quality on design models, and to prevent technical debt and maintenance difficulties. In this paper, we propose a process whose ultimate goal is to enable the checking of these constraints in the implementation stage. Method: The proposed process takes as input a textual specification of an architecture constraint specified at design stage. It translates this specification into meta-programs and then it uses them with aspect-oriented programming to check constraints at the implementation stage and at run-time on object-oriented programs. Results: We experimented an implementation of this process on a set of 12 architecture constraints. The results of this experimentation showed that our process is able to statically and dynamically detect architecture constraint violations on toy object-oriented applications, but also on real-world ones. at source code level and at runtime. It avoids the disappearance of architecture decision knowledge in implementation artifacts, and facilitates later their maintenance

Amazon's evolving ecosystem : a cyber-bookstore and application service provider

HCERES Rang B, FNEGE Rang 3International audienceAmazon.com has been through several stages of development: first as a cyber-bookstore, then a cyber-market, and now an Application Service Provider (ASP). I apply the concept of business ecosystem to describe the evolution of Amazon.com, and highlight the role of web services in the shaping of its ecosystem. The company plays a central role in the ecosystem, working with a network of partners to bring products and services to customers. By continually trying to improve the health of its ecosystem, Amazon ensures its own survival and prosperity. The mechanisms through which Amazon has created its ecosystem are discussed and ideas for firms looking to create analogous business communities are advanced