2,796 research outputs found

    Genetic Structure of the Rice Blast Pathogen (Magnaporthe oryzae) over a Decade in North Central California Rice Fields.

    Get PDF
    Rice blast, caused by the ascomycete Magnaporthe oryzae, is one of the most destructive rice diseases worldwide. Even though the disease has been present in California since 1996, there is no data for the pathogen population biology in the state. Using amplified fragment length polymorphisms and mating-type markers, the M. oryzae population diversity was investigated using isolates collected when the disease was first established in California and isolates collected a decade later. While in the 1990 samples, a single multilocus genotype (MLG) was identified (MLG1), over a decade later, we found 14 additional MLGs in the 2000 isolates. Some of these MLGs were found to infect the only rice blast-resistant cultivar (M-208) available for commercial production in California. The same samples also had a significant decrease of MLG1. MLG1 was found infecting the resistant rice cultivar M-208 on one occasion whereas MLG7 was the most common genotype infecting the M-208. MLG7 was identified in the 2000 samples, and it was not present in the M. oryzae population a decade earlier. Our results demonstrate a significant increase in genotypic diversity over time with no evidence of sexual reproduction and suggest a recent introduction of new virulent race(s) of the pathogen. In addition, our data could provide information regarding the durability of the Pi-z resistance gene of the M-208. This information will be critical to plant breeders in developing strategies for deployment of other rice blast resistance genes/cultivars in the future

    Labelling, Deviance and Media

    Get PDF
    Labelling theory is a perspective that emerged as a distinctive approach to criminology during the 1960s, and was a major seedbed of the radical and critical perspectives that became prominent in the 1970s. It represented the highpoint of an epistemological shift within the social sciences away from positivism – which had dominated criminological enquiry since the late-1800s – and toward an altogether more relativistic stance on the categories and concepts of crime and control. It inspired a huge amount of work throughout the 1960s and 1970s, and still resonates powerfully today. This short chapter maps out some of the ways in which labelling, deviance, media and justice interact at the levels of definition and process. It presents an overview and analysis of key mediatised labelling processes, such as the highly influential concept of moral panics. It discusses how the interconnections between labelling, crime and criminal justice are changing in a context of technological development, cultural change and media proliferation. The conclusion offers an assessment and evaluation of labelling theory’s long-term impact on criminology

    Anelastic deformation of a Pd40Cu30Ni10P20 bulk metallic glass during nanoindentation

    Get PDF
    This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.Time-dependent deformation processes during nanoindentation have been investigated on a Pd40Cu30Ni10P20 bulk metallic glass. Deformation under constant load has been studied as a function of prior loading rate and temperature. The constant-load displacement of the indenter into the sample shows classic relaxation kinetics and reveals the importance of anelasticity for the mechanical behavior of metallic glasses at the nanoscale

    Nonequilibrium dynamics of a simple stochastic model

    Full text link
    We investigate the low-temperature dynamics of a simple stochastic model, introduced recently in the context of the physics of glasses. The slowest characteristic time at equilibrium diverges exponentially at low temperature. On smaller time scales, the nonequilibrium dynamics of the system exhibits an aging regime. We present an analytical study of the scaling behaviour of the mean energy, of its local correlation and response functions, and of the associated fluctuation-dissipation ratio throughout the regime of low temperature and long times. This analysis includes the aging regime, the convergence to equilibrium, and the crossover behaviour between them.Comment: 36 pages, plain tex, 7 figures, to be published by Journal of Physics

    Toy nanoindentation model and incipient plasticity

    Full text link
    A toy model of two dimensional nanoindentation in finite crystals is proposed. The crystal is described by periodized discrete elasticity whereas the indenter is a rigid strain field of triangular shape representing a hard knife-like indenter. Analysis of the model shows that there are a number of discontinuities in the load vs penetration depth plot which correspond to the creation of dislocation loops. The stress vs depth bifurcation diagram of the model reveals multistable stationary solutions that appear as the dislocation-free branch of solutions develops turning points for increasing stress. Dynamical simulations show that an increment of the applied load leads to nucleation of dislocation loops below the nanoindenter tip. Such dislocations travel inside the bulk of the crystal and accommodate at a certain depth in the sample. In agreement with experiments, hysteresis is observed if the stress is decreased after the first dislocation loop is created. Critical stress values for loop creation and their final location at equilibrium are calculated.Comment: 22 pages, 5 figures, to appear in Chaos, Solitons and Fractal

    Relationship between solidification microstructure and hot cracking susceptibility for continuous casting of low-carbon and high-strength low-alloyed steels: A phase-field study

    Get PDF
    © The Minerals, Metals & Materials Society and ASM International 2013Hot cracking is one of the major defects in continuous casting of steels, frequently limiting the productivity. To understand the factors leading to this defect, microstructure formation is simulated for a low-carbon and two high-strength low-alloyed steels. 2D simulation of the initial stage of solidification is performed in a moving slice of the slab using proprietary multiphase-field software and taking into account all elements which are expected to have a relevant effect on the mechanical properties and structure formation during solidification. To account for the correct thermodynamic and kinetic properties of the multicomponent alloy grades, the simulation software is online coupled to commercial thermodynamic and mobility databases. A moving-frame boundary condition allows traveling through the entire solidification history starting from the slab surface, and tracking the morphology changes during growth of the shell. From the simulation results, significant microstructure differences between the steel grades are quantitatively evaluated and correlated with their hot cracking behavior according to the Rappaz-Drezet-Gremaud (RDG) hot cracking criterion. The possible role of the microalloying elements in hot cracking, in particular of traces of Ti, is analyzed. With the assumption that TiN precipitates trigger coalescence of the primary dendrites, quantitative evaluation of the critical strain rates leads to a full agreement with the observed hot cracking behavior. © 2013 The Minerals, Metals & Materials Society and ASM International

    Radiographer gender and breast-screening uptake

    Get PDF
    BreastCheck, the Irish National Breast Screening Programme, screens women aged 50–64. Radiographer recruitment has been a challenge; doubling of numbers is required for full national expansion; to date females are employed. The aim was to document attitudes to male radiographers and effect on return for subsequent screening. In all 85.8% of a random sample of 2000 women recently screened by BreastCheck completed a postal questionnaire. The commonest reaction women felt they would have if there were a male radiographer was embarrassment; significantly greater among those attending a static unit (45.6%) than mobile (38.4%) and in younger women (46%) than older (38.7%). Nine per cent would not have proceeded if the radiographer was male and 9% would only have proceeded if female chaperone present. In all 17.5% (95% CI 15.7–19.4%) agreed that ‘If there were male radiographers I would not return for another screening appointment'; 18.3% were unsure. One-quarter agreed ‘if I heard there could be male radiographers it would change my opinion of BreastCheck for the worse'. The proportions agreeing with these statements did not vary significantly by screening unit type, age group, area of residence or insurance status. This is the largest published study to date of this important issue; the correct balance between equality and programme performance must be identified

    Enumeration of States in a Periodic Glass

    Full text link
    We present an analytic enumeration of the metastable states, NsN_s, in a periodic long-range Josephson array frustrated by a transverse field. We find that the configurational entropy, Sconf≡ln⁡NsS_{conf} \equiv \ln N_s, is extensive and scales with frustration, confirming that the non-random system is glassy. We also find that SconfS_{conf} is different from that of its disordered analogue, despite that fact that the two models share the same dynamical equations
    • 

    corecore