Interlimb transfer of unimanual grasping movement in upper limb amputees - A pilot study.

Background. Inter-hemispheric communication is necessary during uni- manual grip of an object (1). The right and left hands share a level of representation in the motor program that is common to both (2). It could be essential to take into consideration bi- hemispheric activity to adapt prosthesis of individuals with upper limb amputation.\ud Objective. To determine the relevance of the inter-hemispheric dependence in the programing and execution of uni-manual grip in individuals with upper limb amputation.\ud Methods. Five adults with amputation of the upper limb above and below the elbow participated in this study. Each participant was seated and asked to grab and lift an instrumented cylinder with the sound hand 15 times (Figure 1). The cylinder enabled to record in real time the apposition axis (AO) passing by the thrum, the centre of the cylinder and the first finger as well as the forces applied during the griping period of 2000 ms. The participants were assessed during the temporary (PP) and definitive (PD) phases of prosthesis fitting the after the amputation. Student t-tests were used to determine the effect of different prosthetic phases on the force and orientation of the griping hand.\ud Results\ud 1. A significant reduction (p<0.01) of the forces applied by the sound hand between the two prosthetic phase for 4/5 of the participants (Figure 2)\ud 2. Some changes in the gripping orientation when the amputated hand was dominant for 2/3 of the participants (Figure 3) 3. No changes in the gripping orientation when the amputated hand was not dominant\ud Conclusion. Grip programming and execution with sound hand:\ud 1. Change between two prosthetic fitting phases\ud 2. Depend on the inter-hemispheric transfer related to the force regardless on the amputated hand.\ud 3. Depend on the inter-hemispheric transfer related to the gripping orientation only when the amputated side is dominant.\ud Adjustments in griping force and orientation of the prosthesis depending on the grip correction of the sound hand might be respectively more necessary regardless of the amputated hand and when the amputated hand is dominant.\ud Because of the variability between participants concerning the side of amputation and manual dominance, other studies will be required to generalise these results

Glomus intraradices dominates arbuscular mycorrhizal communities in a heavy textured agricultural soil

Arbuscular mycorrhizal fungal (AMF) spore communities were surveyed in a long-term field fertilization experiment in Switzerland, where different amounts of phosphorus (P) were applied to soil. Plots receiving no P as well as plots systematically fertilized in excess to plant needs for 31 years were used to test the hypothesis that application of P fertilizer changes the composition and diversity of AMF communities. AMF spores were isolated from the field soil, identified, and counted so as to quantify the effect of P fertilization on AMF spore density, composition, and diversity. Trap cultures were established from field soil with four host plants (sunflower, leek, maize, and Crotalaria grahamiana), and the spore communities were then analyzed in substrate samples from the pots. Altogether, nine AMF species were detected in the soil. No evidence has been acquired for effect of P fertilization on spore density, composition, and diversity of AMF in both the field soil and in trap cultures. On the other hand, we observed strong effect of crop plant species on spore densities in the soil, the values being lowest under rapeseed and highest under Phacelia tanacetifolia covercrop. The identity of plant species in trap pots also significantly affected composition and diversity of associated AMF communities, probably due to preferential establishment of symbiosis between certain plant and AMF species. AMF spore communities under mycorrhizal host plants (wheat and Phacelia in the fields and four host plant species in trap pots) were dominated by a single AMF species, Glomus intraradices. This resulted in exceptionally low AMF spore diversity that seems to be linked to high clay content of the soi

Collaborative video streaming with Raptor network coding

We investigate the problem of collaborative video streaming with Raptor network coding over overlay networks. We exploit path and source diversity, as well as basic processing capabilities of network nodes to increase the overall throughput and improve the video quality at the clients. We consider an architecture where several streaming servers simultaneously deliver video information to a set of clients. The servers apply Raptor coding on the video packets for error resiliency, and the forwarding peer nodes further combine the Raptor coded video packets in order to increase the packet diversity in the network. We find the optimal source and channel rate allocation in such a collaborative streaming system. The resulting scheme efficiently exploits the available network resources for improved video quality. The experimental evaluation demonstrates that it typically outperforms Raptor video streaming systems that do not use network coding

Network coding: from theory to media streaming

Network coding has recently emerged as an alternative to traditional routing algorithms in communication systems. In network coding, the network nodes can combine the packets they receive before forwarding them to the neighbouring nodes. Intensive research efforts have demonstrated that such a processing in the network nodes can provide advantages in terms of throughput or robustness. These potentials, combined with the advent of ad hoc and wireless delivery architectures have triggered the interest of research community about the application of the network coding principles to streaming applications. This paper describes the potentials of network coding in emerging delivery architectures such as overlay or peer-to-peer networks. It overviews the principles of practical network coding algorithms and outlines the challenges posed by multimedia streaming applications. Finally, it provides a survey of the recent work on the application of network coding to media streaming applications, both in wireless or wired communication scenarios. Promising results have been demonstrated where network coding is able to bring benefits in media streaming applications. However, delay and complexity constraints are often posed as the main challenging issues that still prevent the wide-scale deployment of network coding algorithms in multimedia communication

Network coding node placement for delay minimization in streaming overlays

Network coding has been proposed recently as an efficient method to increase network throughput by allowing network nodes to combine packets instead of simply forwarding them. However, packet combinations in the network may increase delay, complexity and even generate overly redundant information when they are not designed properly. Typically, the best performance is not achieved when all the nodes perform network coding. In this paper, we address the problem of efficiently placing network coding nodes in overlay networks, so that the rate of innovating packets is kept high, and the delay for packet delivery is kept small. We first estimate the expected number of duplicated packets in each network node. These estimations permit to select the nodes that should implement network coding, so that the innovating rate increases. Two algorithms are then proposed for the cases where a central node is aware of the full network statistics and where each node knows the local statistics from its neighbor, respectively. The simulation results show that in the centralized scenario the maximum profit from network coding comes by adding only a few network coding nodes. A similar result is obtained with the algorithm based on local statistics, which moreover performs very close to the centralized solution. These results show that the proper selection of the network coding nodes is crucial for minimizing the transmission delay in streaming overlays

Multiview video representations for quality-scalable navigation

Interactive multiview video (IMV) applications offer to users the freedom of selecting their preferred viewpoint. Usually, in these systems texture and depth maps of captured views are available at the user side, as they permit the rendering of intermediate virtual views. However, the virtual views' quality depends on the distance to the available views used as references and on their quality, which is generally constrained by the heterogeneous capabilities of the users. In this context, this work proposes an IMV scalable system, where views are optimally organized in layers, each one offering an incremental improvement in the interactive navigation quality. We propose a distortion model for the rendered virtual views and an algorithm that selects the optimal views' subset per layer. Simulation results show the efficiency of the proposed distortion model, and that the careful choice of reference cameras permits to have a graceful quality degradation for clients with limited capabilities

Physiol Rep

Obliterative bronchiolitis is the principal long-term problem for lung transplant patients. One of the simplest and most reproducible animal models of obliterative bronchiolitis is heterotopic tracheal transplantation in subcutaneous tissue, where the graft is not primarily vascularized. We demonstrate here the rapid graft revascularization and the kinetics of expression of its angiogenic and lymphatic factors. We performed iso- and allotracheal transplantations harvested on day 0-21. The number of functional blood vessels, quantified after intravenous biotinylated dextran administration, increased from D0 (0 for both iso- and allografts) to D21 (44 +/- 8 vessels/mm(2) in isografts and 22 +/- 3 in allografts, P < 0.001 for both vs. D0). VEGF mRNA expression assessed by qPCR peaked on D1 (4.3-fold increase in isografts and 4.0-fold in allografts, P < 0.0001 for both vs. D0), but receded thereafter. Angiopoietin-1, involved in the maturation of the neoformed vessels, increased later on, by 6.2-fold (P < 0.05) in isografts and 11.5-fold in allografts (P < 0.001) by D21, and angiopoietin-2 by 7.8-fold in isografts (P < 0.05) and 13.8-fold in allografts (P < 0.01). Although always present in the iso- and allografts, there were significantly more and larger LYVE1(+) lymphatic vessels at D21 in allografts than in isografts. Thus, we demonstrate that tracheal grafts are rapidly revascularized by functional blood and lymphatic vessels, due to early VEGF and subsequent angiopoietins expression, which is a new advantage of this model, in addition to its ease of use, reproducibility, and viability in the absence of immunosuppressive treatment

Biomechanical analyses of the performance of Paralympians: From foundation to elite level

Biomechanical analysis of sport performance provides an objective method of determining performance of a particular sporting technique. In particular, it aims to add to the understanding of the mechanisms influencing performance, characterization of athletes, and provide insights into injury predisposition. Whilst the performance in sport of able-bodied athletes is well recognised in the literature, less information and understanding is known on the complexity, constraints and demands placed on the body of an individual with a disability. This paper provides a dialogue that outlines scientific issues of performance analysis of multi-level athletes with a disability, including Paralympians. Four integrated themes are explored the first of which focuses on how biomechanics can contribute to the understanding of sport performance in athletes with a disability and how it may be used as an evidence-based tool. This latter point questions the potential for a possible cultural shift led by emergence of user-friendly instruments. The second theme briefly discusses the role of reliability of sport performance and addresses the debate of two-dimensional and three-dimensional analysis. The third theme address key biomechanical parameters and provides guidance to clinicians, and coaches on the approaches adopted using biomechanical/sport performance analysis for an athlete with a disability starting out, to the emerging and elite Paralympian. For completeness of this discourse, the final theme is based on the controversial issues on the role of assisted devices and the inclusion of Paralympians into able-bodied sport is also presented. All combined, this dialogue highlights the intricate relationship between biomechanics and training of individuals with a disability. Furthermore, it illustrates the complexity of modern training of athletes which can only lead to a better appreciation of the performances to be delivered in the London 2012 Paralympic Games

Visual Distortions in 360-degree Videos.

Omnidirectional (or 360°) images and videos are emergent signals being used in many areas, such as robotics and virtual/augmented reality. In particular, for virtual reality applications, they allow an immersive experience in which the user can interactively navigate through a scene with three degrees of freedom, wearing a head-mounted display. Current approaches for capturing, processing, delivering, and displaying 360° content, however, present many open technical challenges and introduce several types of distortions in the visual signal. Some of the distortions are specific to the nature of 360° images and often differ from those encountered in classical visual communication frameworks. This paper provides a first comprehensive review of the most common visual distortions that alter 360° signals going through the different processing elements of the visual communication pipeline. While their impact on viewers' visual perception and the immersive experience at large is still unknown-thus, it is an open research topic-this review serves the purpose of proposing a taxonomy of the visual distortions that can be encountered in 360° signals. Their underlying causes in the end-to-end 360° content distribution pipeline are identified. This taxonomy is essential as a basis for comparing different processing techniques, such as visual enhancement, encoding, and streaming strategies, and allowing the effective design of new algorithms and applications. It is also a useful resource for the design of psycho-visual studies aiming to characterize human perception of 360° content in interactive and immersive applications