DIET : new developments and recent results

Among existing grid middleware approaches, one simple, powerful, and flexibleapproach consists of using servers available in different administrative domainsthrough the classic client-server or Remote Procedure Call (RPC) paradigm.Network Enabled Servers (NES) implement this model also called GridRPC.Clients submit computation requests to a scheduler whose goal is to find aserver available on the grid. The aim of this paper is to give an overview of anNES middleware developed in the GRAAL team called DIET and to describerecent developments. DIET (Distributed Interactive Engineering Toolbox) is ahierarchical set of components used for the development of applications basedon computational servers on the grid.Parmi les intergiciels de grilles existants, une approche simple, flexible et performante consiste a utiliser des serveurs disponibles dans des domaines administratifs différents à travers le paradigme classique de l’appel de procédure àdistance (RPC). Les environnements de ce type, connus sous le terme de Network Enabled Servers, implémentent ce modèle appelé GridRPC. Des clientssoumettent des requêtes de calcul à un ordonnanceur dont le but consiste àtrouver un serveur disponible sur la grille.Le but de cet article est de donner un tour d’horizon d’un intergiciel développédans le projet GRAAL appelé DIET 1. DIET (Distributed Interactive Engineering Toolbox) est un ensemble hiérarchique de composants utilisés pour ledéveloppement d’applications basées sur des serveurs de calcul sur la grille

Efficient fault tolerance for selected scientific computing algorithms on heterogeneous and approximate computer architectures

Scientific computing and simulation technology play an essential role to solve central challenges in science and engineering. The high computational power of heterogeneous computer architectures allows to accelerate applications in these domains, which are often dominated by compute-intensive mathematical tasks. Scientific, economic and political decision processes increasingly rely on such applications and therefore induce a strong demand to compute correct and trustworthy results. However, the continued semiconductor technology scaling increasingly imposes serious threats to the reliability and efficiency of upcoming devices. Different reliability threats can cause crashes or erroneous results without indication. Software-based fault tolerance techniques can protect algorithmic tasks by adding appropriate operations to detect and correct errors at runtime. Major challenges are induced by the runtime overhead of such operations and by rounding errors in floating-point arithmetic that can cause false positives. The end of Dennard scaling induces central challenges to further increase the compute efficiency between semiconductor technology generations. Approximate computing exploits the inherent error resilience of different applications to achieve efficiency gains with respect to, for instance, power, energy, and execution times. However, scientific applications often induce strict accuracy requirements which require careful utilization of approximation techniques. This thesis provides fault tolerance and approximate computing methods that enable the reliable and efficient execution of linear algebra operations and Conjugate Gradient solvers using heterogeneous and approximate computer architectures. The presented fault tolerance techniques detect and correct errors at runtime with low runtime overhead and high error coverage. At the same time, these fault tolerance techniques are exploited to enable the execution of the Conjugate Gradient solvers on approximate hardware by monitoring the underlying error resilience while adjusting the approximation error accordingly. Besides, parameter evaluation and estimation methods are presented that determine the computational efficiency of application executions on approximate hardware. An extensive experimental evaluation shows the efficiency and efficacy of the presented methods with respect to the runtime overhead to detect and correct errors, the error coverage as well as the achieved energy reduction in executing the Conjugate Gradient solvers on approximate hardware

Brain-Inspired Computing

This open access book constitutes revised selected papers from the 4th International Workshop on Brain-Inspired Computing, BrainComp 2019, held in Cetraro, Italy, in July 2019. The 11 papers presented in this volume were carefully reviewed and selected for inclusion in this book. They deal with research on brain atlasing, multi-scale models and simulation, HPC and data infra-structures for neuroscience as well as artificial and natural neural architectures

Distributed Control for Collective Behaviour in Micro-unmanned Aerial Vehicles

Full version unavailable due to 3rd party copyright restrictions.The work presented herein focuses on the design of distributed autonomous controllers for collective behaviour of Micro-unmanned Aerial Vehicles (MAVs). Two alternative approaches to this topic are introduced: one based upon the Evolutionary Robotics (ER) paradigm, the other one upon flocking principles. Three computer simulators have been developed in order to carry out the required experiments, all of them having their focus on the modelling of fixed-wing aircraft flight dynamics. The employment of fixed-wing aircraft rather than the omni-directional robots typically employed in collective robotics significantly increases the complexity of the challenges that an autonomous controller has to face. This is mostly due to the strict motion constraints associated with fixed-wing platforms, that require a high degree of accuracy by the controller. Concerning the ER approach, the experimental setups elaborated have resulted in controllers that have been evolved in simulation with the following capabilities: (1) navigation across unknown environments, (2) obstacle avoidance, (3) tracking of a moving target, and (4) execution of cooperative and coordinated behaviours based on implicit communication strategies. The design methodology based upon flocking principles has involved tests on computer simulations and subsequent experimentation on real-world robotic platforms. A customised implementation of Reynolds’ flocking algorithm has been developed and successfully validated through flight tests performed with the swinglet MAV. It has been notably demonstrated how the Evolutionary Robotics approach could be successfully extended to the domain of fixed-wing aerial robotics, which has never received a great deal of attention in the past. The investigations performed have also shown that complex and real physics-based computer simulators are not a compulsory requirement when approaching the domain of aerial robotics, as long as proper autopilot systems (taking care of the ”reality gap” issue) are used on the real robots.EOARD (European Office of Aerospace Research & Development), euCognitio

Design Development Test and Evaluation (DDT and E) Considerations for Safe and Reliable Human Rated Spacecraft Systems

A team directed by the NASA Engineering and Safety Center (NESC) collected methodologies for how best to develop safe and reliable human rated systems and how to identify the drivers that provide the basis for assessing safety and reliability. The team also identified techniques, methodologies, and best practices to assure that NASA can develop safe and reliable human rated systems. The results are drawn from a wide variety of resources, from experts involved with the space program since its inception to the best-practices espoused in contemporary engineering doctrine. This report focuses on safety and reliability considerations and does not duplicate or update any existing references. Neither does it intend to replace existing standards and policy

Aeronautical Engineering, A Continuing Bibliography With Indexes

This bibliography lists 693 reports, articles and other documents introduced into the NASA scientific and technical information system in September 1984

Guardians, Start of a Light Novel Series

The fictional story of Edward Alfred and his friends, a group of teens known simply as the Guardians. They safeguard the planet in secrecy to protect humanity until it is ready to exit childhood and enter the greater interstellar community

Light inputs to dopaminergic amacrine cells of the mammalian retina

Background: The retina responds to light over a wide range of operational conditions, surpassing 10 units in a logarithmic scale. Adaptation of the retina to the particular presenting light conditions relies considerably on modulation of retinal pathways by dopamine, which is released in response to light or circadian rhythms exclusively from dopaminergic amacrine cells. Rods, cones and intrinsically photoresponsive retinal ganglion cells (ipRGCs) have all been shown to input into dopaminergic amacrine cells. However, the pathways that these photoreceptors employ to ultimately trigger dopamine release in response to light remain unclear. Methods: Ultra-high performance liquid chromatography separation and tandem mass spectrometry detection was used to quantify dopamine, and its primary metabolite 3,4-dihidroxyphenylacetic acid (DOPAC). Retinal dopamine release was assessed under various conditions, in a variety of mouse models, using two complementary experimental designs: in vivo anaesthetised mice and ex vivo explanted retinae. Conclusions: This thesis provides novel evidence about dopamine dynamics in a variety of light conditions, transgenic mouse models and presence of pharmacological agents. Surprisingly, I found that rod input is both necessary and sufficient to evoke light-induced release dopamine across a wide range of light intensities, without quantifiable contribution from cones or ipRGCs, suggesting that electrophysiological inputs do not match dopamine release. Further, this data suggests that the main pathway that drives this increase in light-induced dopamine release at light intensities where rods should be saturated is the primary rod pathway (with smaller contributions from the secondary and tertiary pathways) and involves bleaching adaptation of rods

Functional Characterization and Classification of Genes Essential to Flower Induction, Flower Development, and Seed Development in Populus and Eucalyptus

This dissertation consists of four studies of Populus and Eucalyptus biotechnology and genomic science: 1) induction of floral sterility by tapetal expression of the ribonuclease Barnase in Populus; 2) CRISPR Cas9-mediated gene editing targeting LEAFY (LFY) and AGAMOUS (AG) homologs in Populus; 3) induction of floral sterility by CRISPR Cas9 mutagenesis of the LEAFY (LFY) gene homolog in hybrid Eucalyptus; and 4) Gene expression analysis using RNASeq during flowering and seed capsule development in Eucalyptus grandis (E. grandis). The Populus genus includes species and hybrids that are favored in commercial and research settings because of their fast growth and their relative ease of transformation and regeneration. The Eucalyptus genus is the most planted genus of hardwood trees in the world. Eucalyptus species and hybrids are grown for wood, pulp, essential oils, and honey. Regardless of their value, the genes and genomes of trees are not as well-studied as those of other plant and crop species, including Arabidopsis, Antirrhinum, maize, and tobacco. We conducted four studies to address research needs associated with tree floral biology and genetic containment. In study 1, we performed a four-year field trial of transgenic male poplars that expressed the ribonuclease Barnase in the tapetal layer of their anthers. The purpose was to test the efficiency of this RNAse at disrupting pollen development and determine whether growth was affected. During the trial, 17 of 18 transgenic barnase-expressing trees grew on average 40% slower than the WT control trees (i.e., no transformation). The 18 Barnase-expressing trees did not have detectable production of viable pollen In study 2, we evaluated the mutation efficiency and mutation spectra induced by four CRISPR Cas9 nucleases targeting two different sites in three essential flowering genes, LFY and the two AG homologs in Populus. The average mutation rate was 77.5%; a higher mutation rate than observed before the advent of CRISPR. No undesirable mutations were seen in 310 potential “off-target” loci, and no mutations were seen at any of the target sites in the empty-vector (“Cas9-only” plus markers) control population. In study 3, we analyzed the mutation efficiency and efficacy of CRISPR Cas9 nucleases at inducing knockout mutations in the LFY ortholog in Eucalyptus. In 68 transgenic lines, the average mutation rate was 98.5%. After evaluating the floral morphology of 32 lines in the greenhouse, we calculated the average loss-of-function (LOF) rate to be 91%. Lines with LOF mutations failed to produce flowers and viable gametes. Meanwhile, the LOF mutations did not affect growth. The expression of genes upstream and downstream of LFY in the floral development pathway suggest that the mutant flowers were not transitioning adequately between inflorescences and flowers. However, occasional sterile and underdeveloped floral organs were seen. Further long-term research is necessary to determine whether mutation of LFY is a fully reliable containment technology. In study 4, we examined the gene expression of 20 samples corresponding to seven different floral and vegetative tissues during late flowering and early seed capsule development in E. grandis. Expression libraries were created for flowers and seed capsules at five time points between anthesis and early seed development. Libraries were also constructed for mature pollen and mature leaf (i.e., the vegetative control). We identified differentially expressed genes by comparing the expression of all reproductive tissues to mature flower and also by comparing expression among reproductive tissues. In total we identified 27,450 unique transcripts, and identified 11,438 differentially expressed transcripts (false discovery rate of 0.05, filtered to genes with at least double the expression if positive change, or half the expression if negative change). We found that genes involved in the biosynthesis of phenylpropanoids were important and differentially expressed during anther and seed capsule maturation. Flower development genes were expressed in tissues homologous to those of other flowers previously characterized, e.g. Arabidopsis and Anthirihum. The transcriptome data provides a rich resource to support studies of floral evolution in the Myrtales, and will inform efforts to breed or genetically engineer sexual development in Eucalyptus