Epidemic spread of smut fungi (Quambalaria) by sexual reproduction in a native pathosystem

Quambalaria are fungal pathogens of Corymbia, Eucalyptus and related genera of Myrtaceae. They are smut fungi (Ustilaginomycota) described from structures that resemble conidia and conidiophores. Whether these spore forms have asexual or sexual roles in life cycles of Quambalaria is unknown. An epidemic of Q. pitereka destroyed plantations of Corymbia in New South Wales and Queensland (Australia) in 2008. We sampled 177 individuals from three plantations of C. variegata and used AFLPs to test hypotheses that the epidemic was spread by asexual reproduction and dominated by a single genotype. There was high genotypic diversity across ≥600 AFLP loci in the pathogen populations at each plantation, and evidence of sexual reproduction based on neighbour-net analyses and rejection of linkage disequilibrium. The populations were not structured by host or location. Our data did not support a hypothesis of asexual reproduction but instead that Q. pitereka spreads exclusively by sexual reproduction, similar to life cycles of other smut fungi. Epidemics were exacerbated by monocultures of Corymbia established from seed collected from a single provenance. This study showcases an example of an endemic pathogen, Q. pitereka, with a strictly outbreeding life cycle that has caused epidemics when susceptible hosts were planted in large monoculture plantations

Phylogeny of the Quambalariaceae fam. nov., including important Eucalyptus pathogens in South Africa and Australia

The genus Quambalaria consists of plant-pathogenic fungi causing disease on leaves and shoots of species of Eucalyptus and its close relative, Corymbia. The phylogenetic relationship of Quambalaria spp., previously classified in genera such as Sporothrix and Ramularia, has never been addressed. It has, however, been suggested that they belong to the basidiomycete orders Exobasidiales or Ustilaginales. The aim of this study was thus to consider the ordinal relationships of Q. eucalypti and Q. pitereka using ribosomal LSU sequences. Sequence data from the ITS nrDNA were used to determine the phylogenetic relationship of the two Quambalaria species together with Fugomyces (= Cerinosterus) cyanescens. In addition to sequence data, the ultrastructure of the septal pores of the species in question was compared. From the LSU sequence data it was concluded that Quambalaria spp. and F. cyanescens form a monophyletic clade in the Microstromatales, an order of the Ustilaginomycetes. Sequences from the ITS region confirmed that Q. pitereka and Q. eucalypti are distinct species. The ex-type isolate of F. cyanescens, together with another isolate from Eucalyptus in Australia, constitute a third species of Quambalaria, Q. cyanescens (de Hoog & G.A. de Vries) Z.W. de Beer, Begerow & R. Bauer comb. nov. Transmission electron-microscopic studies of the septal pores confirm that all three Quambalaria spp. have dolipores with swollen lips, which differ from other members of the Microstromatales (i.e. the Microstromataceae and Volvocisporiaceae) that have simple pores with more or less rounded pore lips. Based on their unique ultrastructural features and the monophyly of the three Quambalaria spp. in the Microstromatales, a new family, Quambalariaceae Z.W. de Beer, Begerow & R. Bauer fam. nov., is described

Towing tank and flume testing of passively adaptive composite tidal turbine blades

Composite tidal turbine blades with bend-twist (BT) coupled layups allow the blade to self-adapt to local site conditions by passively twisting. Passive feathering has the potential to increase annual energy production and shed thrust loads and power under extreme tidal flows. Decreased hydrodynamic thrust and power during extreme conditions means that the turbine support structure, generator, and other components can be sized more appropriately, resulting in a higher utilization factor and increased cost effectiveness

Development and initial application of a blade design methodology for overspeed power-regulated tidal turbines

The range and variability of flow velocities in which horizontal axis tidal stream turbines operate introduces the requirement for a power regulation method in the system. Overspeed power regulation (OSPR) has the potential to improve the structural robustness and decrease the complexity associated with active pitch power regulation methods, while removing the difficulties of operating in stalled flow. This paper presents the development of a methodology for the design of blades to be used in such systems. The method requires a site depth, maximum flow velocity and rated power or flow speed as input parameters. The pitch setting, twist and chord distribution were set as input parameters, variable through the use of alteration functions. Rotor performance has been broken down into OSPR performance metrics which consider coefficients of power and thrust, and cavitation inception. Three visual-numerical tools have been developed: the OSPR performance metrics were used in conjunction with a one-at-a-time sensitivity analysis approach to develop a design space; cavitation inception analyses gave plots of converging cavitation and pressure terms for each blade section; the local angle of attack and torque distribution across the blade designs were plotted at key turbine operation states. Alterations to pitch setting and twist distribution are shown to have most impact upon the design requirement of increased gradient in the rotor speed-efficiency relationship in the overspeed region; coupled with such alterations, targeted changes to the chord distribution have been shown to increase the maximum efficiency. The prevention of cavitation has been highlighted as a driver for speed-limiting design alterations. While facilitating blade design, the methodology also produces experiential knowledge which can be stored, and shared in graphical format

Testing of quantum phase in matter wave optics

Various phase concepts may be treated as special cases of the maximum likelihood estimation. For example the discrete Fourier estimation that actually coincides with the operational phase of Noh, Fouge`res and Mandel is obtained for continuous Gaussian signals with phase modulated mean.Since signals in quantum theory are discrete, a prediction different from that given by the Gaussian hypothesis should be obtained as the best fit assuming a discrete Poissonian statistics of the signal. Although the Gaussian estimation gives a satisfactory approximation for fitting the phase distribution of almost any state the optimal phase estimation offers in certain cases a measurable better performance. This has been demonstrated in neutron--optical experiment.Comment: 8 pages, 4 figure

A profusion of upstream open reading frame mechanisms in polyamine-responsive translational regulation

In many eukaryotic mRNAs one or more short ‘upstream’ open reading frames, uORFs, precede the initiator of the main coding sequence. Upstream ORFs are functionally diverse as illustrated by their variety of features in polyamine pathway biosynthetic mRNAs. Their propensity to act as sensors for regulatory circuits and to amplify the signals likely explains their occurrence in most polyamine pathway mRNAs. The uORF-mediated polyamine responsive autoregulatory circuits found in polyamine pathway mRNAs exemplify the translationally regulated dynamic interface between components of the proteome and metabolism

Tow-tank testing of a 1/20th scale horizontal axis tidal turbine with uncertainty analysis

Tidal turbine developers and researchers use small scale testing (i.e. tow tank and flume testing) as a cost effective and low risk way to conduct proof-of-concept studies and evaluate early stage device performance. This paper presents experimental performance data for a three-bladed 1/20th scale NREL S814 tidal turbine rotor, produced at the 4.6 × 2.5 m and 76 m long Kelvin Hydrodynamics Laboratory tow tank at Strathclyde University. The rotor performance was characterised from very low tip speed ratios to runaway for four carriage speeds. A maximum CP of 0.285 and a maximum CT of 0.452 were recorded at tip speed ratios of 3.53 and 4.45 for a carriage speed of 1 m/s. The uncertainty in the instrument calibration and experimental measurements was quantified, allowing accurate representation of the experiments in numerical models. The methodology behind the uncertainty calculations is described in this paper. The uncertainty in the experimental measurements was found to be less than 5% for over 87% of the tests. Reynolds number scaling effects were found to be influential on the rotor performance in the range of velocities tested

Quantum Phase and Quantum Phase Operators: Some Physics and Some History

After reviewing the role of phase in quantum mechanics, I discuss, with the aid of a number of unpublished documents, the development of quantum phase operators in the 1960's. Interwoven in the discussion are the critical physics questions of the field: Are there (unique) quantum phase operators and are there quantum systems which can determine their nature? I conclude with a critique of recent proposals which have shed new light on the problem.Comment: 19 pages, 2 Figs. taken from published articles, LaTeX, to be published in Physica Scripta, Los Alamos preprint LA-UR-92-352

Interfacial characteristics and microstructural evolution of ceramics exposed to high temperature sand laden combustion environments

Sand laden combustion environments are a current challenge plaguing ceramic thermal barrier coatings (TBCs) and environmental barrier coatings (EBCs) on metallic and emerging ceramic matrix composite (CMC) turbomachinery components. Exposure of thermal and environmental barrier coatings on ceramic matrix composites to environmental particulate laden deteriorates the ceramic structure via chemical reactions and infiltration into pore structures. The challenge of environmental particulates, collectively referred to as calcium-magnesium-aluminosilicate (CMAS), is expected to be exacerbated in future components that utilize ceramic matric composites (CMCs), since the higher operating temperatures will accelerate particulate melting, infiltration, and diffusion kinetics. This study first presents efforts at ARL to develop sandphobic coatings resistant to CMAS infiltration and deposition. The results of a recent full scale sand ingestion engine test used to evaluate several ARL layered and blended coating compositions are presented. The study also includes the evaluation of interactions of CMAS plasma sprayed environmental barrier coatings and HfO2-Si bond coats on SiC/SiC CMCs in rig simulated engine test conditions. The focus is on the microstructural evolution of the coatings and the interfacial characteristics between the TBCs and EBCs and CMAS. Interfaces between coating constituents are also of interest in order to tailor coatings with superior thermal, structural, and chemical characteristics. Controlled studies on YSZ-based ceramic compacts are also performed in order to gain a more fundamental understanding of the effect of porosity on infiltration kinetics, as well as the nature of interfaces and interfacial products wrought by CMAS infiltration into YSZ ceramic grain boundaries. These model studies on YSZ are conducted by immersing the ceramic compacts into AFRL-02 sand and exposing the system to temperatures of up to 1300 °C. X-ray diffraction, scanning electron microscopy, transmission electron microscopy, electron back scattered diffraction, and focused ion beam (milling and imaging) are utilized for microstructural and interfacial characterization of the CMAS reacted thermal and environmental barrier coating systems