ParisTech

About: ParisTech is a education organization based out in Paris, France. It is known for research contribution in the topics: Finite element method & Residual stress. The organization has 1888 authors who have published 1965 publications receiving 55532 citations. The organization is also known as: Paris Institute of Technology & ParisTech Développement.

PART OF A SPECIAL ISSUE ON FUNCTIONAL -STRUCTURAL PLANT MODELLING Using virtual 3-D plant architecture to assess fungal pathogen splash dispersal in heterogeneous canopies: a case study with cultivar mixtures and a non-specialized disease causal agent

Abstract: †Backgroundand Aims Recent developments in plant disease management have led to a growinginterest in alter-nativestrategies,suchasincreasinghostdiversityanddecreasingtheuseofpesticides.Useofcultivarmixturesisoneoption,allowingthe spreadof plantepidemicstobesloweddown.As dispersal of fungalfoliarpathogensover shortdistances by rain-splash droplets is a major contibutor to the spread of disease, this study focused on modelling thephysicalmechanismsinvolvedindispersalofanon-specializedpathogenwithinheterogeneouscanopiesofcultivarmixtures, with the aim of optimizing host diversification at the intra-field level.†MethodsVirtual3-Dwheat-likeplants(Triticumaestivum)wereusedtoconsiderinteractionsbetweenplantarchi-tecture and disease progression in heterogeneous canopies. A combined mechanistic and stochastic model, takingintoaccountsplashdropletdispersalandhostquantitativeresistancewithina3-Dheterogeneouscanopy,wasdevel-oped. It consists of four sub-models that describe the spatial patterns of two cultivars within a complex canopy, thepathwayof rain-splash droplets within this canopy, the proportion of leaf surface area impacted by dispersal via thedroplets and the progression of disease severity after each dispersal event.†Key Results Different spatial organization, proportions and resistance levels of the cultivars of two-componentmixtures were investigated. For the eight spatial patterns tested, the protective effect against disease was found tovary by almost 2-fold, with the greatest effect being obtained with the smallest genotype unit area, i.e. the groundarea occupied by an independent unit of the host population that is genetically homogeneous. Increasing both thedifference between resistance levels and the proportion of the most resistant cultivar often resulted in a greater pro-tective effect; however, this was not observed for situations in which the most resistant of the two cultivars in themixture had a relatively low level of resistance.†Conclusions The results showagreement with previous data obtained using experimental approaches. They dem-onstrate that in order to maximize the potential mixture efficiencyagainsta splash-dispersed pathogen, optimal sus-ceptible/resistantcultivarproportions(rangingfrom1/9to5/5)havetobeestablishedbasedonhostresistancelevels.Theresultsalso show thattakingintoaccountdispersal processesinexplicit3-D plantcanopiescanbea keytoolforinvestigating disease progression in heterogeneous canopies such as cultivar mixtures.Key words: Functional–structuralplantmodelling, intra-fielddiversity,wheatdisease,Triticumaestivum, cultivarmixture, splash dispersal, fungal pathogen, mechanistic modelling, 3-D plant modelling, quantitative resistance.

Evaluation of 6to4 and ISATAP on a test LAN

Abstract: Coexistence of IPv4 and IPv6 bears problem of incompatibility, as IPv6 and IPv4 headers are different from each other. To counter this problem, three solutions are possible: a) making every device dual stack, b) translation, c) tunneling. Tunneling stands out as the best possible solution. Among the IPv6 tunneling techniques, this paper evaluates the performance of two recent IPv6 tunneling techniques: 6to4 and ISATAP. These protocols were implemented on real test bed setup, on Microsoft Windows (MS Windows XP and MS Windows Server 2003) and Linux operating systems. Five to six devices were used to setup the whole test bed. Each protocol was then implemented on the setup using specific configuration commands, available online at various sources. UDP based audio streaming, video streaming, and TCP based ICMP-ping traffic was run. Four different runs of IPv6 traffic were routed over the setup for both IPv6 tunneling protocols. The average of the data was taken to generate graphs and final results. The performance of these tunneling techniques has been evaluated through certain parameters, namely: throughput, end to end delay (E2ED), round trip time (RTT), and jitter.

The ecological genetics of Pseudomonas syringae from kiwifruit leaves

Abstract: Interactions between commensal microbes and invading pathogens are understudied, despite their likely effects on pathogen population structure and infection processes. We describe the population structure and genetic diversity of a broad range of co-occurring Pseudomonas syringae isolated from infected and uninfected kiwifruit during an outbreak of bleeding canker disease caused by P. syringae pv. actinidiae (Psa) in New Zealand. Overall population structure was clonal and affected by ecological factors including infection status and cultivar. Most isolates are members of a new clade in phylogroup 3 (PG3a), also present on kiwifruit leaves in China and Japan. Stability of the polymorphism between pathogenic Psa and commensal P. syringae PG3a isolated from the same leaf was tested using reciprocal invasion from rare assays in vitro and in planta. P. syringae G33C (PG3a) inhibited Psa NZ54, while the presence of Psa NZ54 enhanced the growth of P. syringae G33C. This effect could not be attributed to virulence activity encoded by the Type 3 secretion system of Psa. Together our data contribute toward the development of an ecological perspective on the genetic structure of pathogen populations.