T cell tolerance to the skin: a central role for central tolerance

T cell tolerance to self-antigens is believed to be achieved in a two-step process. The first step, called central tolerance, takes place in the thymus. The second step takes place outside the thymus in secondary lymphoid organs. One may ask why two mechanisms are needed to insure T cell tolerance. These two mechanisms share redundant functions and dysfunctions, leading to T cell-mediated autoimmune syndromes. By reviewing the literature on relevant animal models for T cell tolerance and our own recent findings, we are providing evidences that only central tolerance is acting for the ski

Impact of Asynchronism on GPU Accelerated Parallel Iterative Computations

International audienceWe study the impact of asynchronism on parallel iterative algorithms in the particular context of local clusters of workstations including GPUs. The application test is a classical PDE problem of advection-diffusion-reaction in 3D. We propose an asynchronous version of a previously developed PDE solver using GPUs for the inner computations. The algorithm is tested with two kinds of clusters, a homogeneous one and a heterogeneous one (with different CPUs and GPUs)

Dynamic Load Balancing and Efficient Load Estimators for Asynchronous Iterative Algorithms

In a previous paper~\cite{HPCS2002}, we have shown the very high power of asynchronism for parallel iterative algorithms in a global context of grid computing. In this article, we study the interest of coupling load balancing with asynchronism in such algorithms. After proposing a non-centralized version of dynamic load balancing which is best suited to asynchronism, we verify its efficiency by some experiments on a general Partial Differential Equation (PDE) problem. Finally, we give some general conditions for the use of load balancing to obtain good results with this kind of algorithms and discuss the choice of the residual as an efficient load estimator

An efficient and robust decentralized algorithm for detecting the global convergence in asynchronous iterative algorithms

URL : http://vecpar.fe.up.pt/2008/papers/25.pdfInternational audienceIn this paper we present a practical, efficient and robust algorithm for detecting the global convergence in any asynchronous iterative process. A proven theoretical version, together with a first practical version, was presented in [1]. However, the main drawback of that first practical version was to require the determination of the maximal communication time between any couple of nodes in the system during the entire iterative process. The version presented in this paper does not require any additional information on the parallel system while always ensuring correct detections

Performance comparison of parallel programming environments for implementing AIAC algorithms

International audienceAIAC algorithms (Asynchronous Iterations Asynchronous Communications) are a particular class of parallel iterative algorithms. Their asynchronous nature makes them more efficient than their synchronous counterparts in numerous cases as has already been shown in previous works. The first goal of this article is to compare several parallel programming environments in order to see if there is one of them which is best suited to efficiently implement AIAC algorithms. The main criterion for this comparison consists in the performances achieved in a global context of grid computing for two classical scientific problems. Nevertheless, we also take into account two secondary criteria which are the ease of programming and the ease of deployment. The second goal of this study is to extract from this comparison the important features that a parallel programming environment must have in order to be suited for the implementation of AIAC algorithms

A decentralized convergence detection algorithm for asynchronous parallel iterative algorithms

We introduce a theoretical algorithm and its practical version to perform decentralized detection of the global convergence of parallel asynchronous iterative algorithms. We prove that even if the algorithm is completely decentralized, the detection of global convergence is achieved on one processor under the classical conditions. The proposed algorithm is very useful in the context of grid computing in which the processors are distributed and in which detecting the convergence on a master processor may be penalizing or even impossible as in Peer to Peer computations framework. Finally, the efficiency of the practical algorithm is illustrated in a typical experiment

CARD14 gain-of-function mutation alone is sufficient to drive IL-23/IL-17-mediated psoriasiform skin inflammation in vivo

Rare autosomal dominant mutations in the gene encoding the keratinocyte signaling molecule, Caspase Recruitment Domain-Containing Protein 14 (CARD14), have been associated with an increased susceptibility to psoriasis but the physiological impact of CARD14 gain-of-function mutations remains to be fully determined in vivo. Here, we report that heterozygous mice harboring a CARD14 gain-of-function mutation (Card14ΔE138) spontaneously develop a chronic psoriatic phenotype with characteristic scaling skin lesions, epidermal thickening, keratinocyte hyperproliferation, hyperkeratosis and immune cell infiltration. Affected skin of these mice is characterized by elevated expression of anti-microbial peptides, chemokines and cytokines (including Th17 cell-signature cytokines), and an immune infiltrate rich in neutrophils, myeloid cells and T-cells, reminiscent of human psoriatic skin. Disease pathogenesis was driven by the IL-23/IL-17 axis and neutralization of IL-23p19, the key cytokine in maintaining Th17 cell polarization, significantly reduced skin lesions and the expression of antimicrobial peptides and pro-inflammatory cytokines. Therefore, hyperactivation of CARD14 alone is sufficient to orchestrate the complex immunopathogenesis that drives Th17-mediated psoriasis skin disease in vivo

ALTA: Asynchronous Loss Tolerant Algorithms for Grid Computing

International audienceThis paper describes an environment dedicated to the building of efficient scientific applications for the Grid on top of unreliable communication networks. Nowadays, scientific computing appli-cations are usually built on top of reliable communication proto-cols (such as TCP). Nevertheless, the additional cost introduced by the reliability layer is not negligible in wide area network-based grid environments. On the other hand, data loss in communications may have a dramatic impact over the performance – if not over the correctness – of classical parallel algorithms. However, a particular class of parallel iterative algorithms hap-pens to be tolerant to such losses. This is the class of asynchronous iterative algorithms, which are commonly used in large scientific applications. They are particularly prone to a good communica-tion/computation overlap since processors are no more synchro-nized. In this study, we aim at proposing a new architecture suit-able for the development of asynchronous iterative algorithms tolerant to message losses