Jack-of-all-trades and master of many? How does associated rhizobial diversity influence the colonization success of Australian Acacia species?

Aim To evaluate the role of rhizobial diversity, and symbiotic promiscuity, on the invasive ability of Australian acacias (Acacia species in subgenus Phyllodineae native to Australia). Location Global. Methods A bibliographic review of the rhizobial diversity associated with Australian Acacia species was performed to assess symbiotic promiscuity for invasive and non-invasive species. The rhizobial diversity associated with Acacia dealbata and A. saligna in Australia and Portugal and with A. pycnantha in Australia and South Africa was assessed by 16S rDNA and intergenic spacer sequencing of bacteria isolated from field-collected nodules. Results All studied Australian acacias are nodulated by strains in the genus Bradyrhizobium, which appears to be the dominant group of acacia symbionts in native and non-native soils. Both literature and experimental data from this study suggest that Australian bradyrhizobia might have been co-introduced with acacias to new geographical regions. The studied Acacia species can also harbour other root-nodulating alpha and betaproteobacteria genera, although these are less abundant than Bradyrhizobium. Main conclusions There is no clear difference in the diversity of rhizobial species associated with invasive and non-invasive Australian acacias. All studied invasive acacias nodulate in both native and non-native regions, harbouring predominantly Bradyrhizobium strains but showing some degree of symbiotic promiscuity. The co-introduction of compatible root-nodulating bacteria from Australia might explain the establishment of invasive populations, but novel associations with rhizobia from the invaded soils are also possible. Invasive legumes might use both strategies but species with low symbiotic promiscuity would become invasive only if compatible bacteria are co-introduced in the new regions. The progress of invasion and the impacts on the invaded ecosystems might also differ depending on the nodulation strategy.Centre of Excellence for Invasion Biolog

On-line automatic controller tuning of a multivariable grinding mill circuit using Bayesian optimisation

Process controllers are abundant in the industry and require attentive tuning to achieve optimal performance. While tuning controllers by the most primitive method of trial and error is possible, it often leads to sub-optimal performance if not conducted by a skilled expert. It is much more appealing to develop an on-line, sample efficient, automated tuner which can optimise the performance of a given controller to the task at hand. The automatic tuning procedure can be conducted during commissioning, when poor controller performance is observed or when process conditions have changed. The problem statement is formulated as the minimisation of an objective function constructed to achieve the desired controller performance. In this context the automatic tuning problem of multi-input multi-output (MIMO) controllers is considered within the framework of Bayesian optimisation and applied in simulation to an ore milling circuit with three manipulated and three controlled variables. Regulatory and set point tracking controllers are tuned automatically and are shown to achieve better performance than a reference controller.http://www.elsevier.com/locate/jproconthj2023Electrical, Electronic and Computer Engineerin

On-line automatic controller tuning using Bayesian optimisation - a bulk tailings treatment plant case study

The automatic tuning problem of multiple-input-multiple-output (MIMO) controllers is considered within the framework of Bayesian optimisation and applied in simulation to a bulk tailings treatment process. The aim is to develop a model free, on-line, automatic tuner which can optimise the performance of a given controller to the task at hand. The automatic tuning procedure can be conducted during commissioning, when poor controller performance is observed or when the process has changed. Simulations indicate that the method is able to locate the optimal tuning parameters for the bulk tailings treatment process as compared to a de-coupled controller developed from a model of the process. The parameters were obtained from an objective function which was balanced and weighted according to the response required.https://www.journals.elsevier.com/ifac-papersonlineElectrical, Electronic and Computer Engineerin

The ANTARES Optical Beacon System

ANTARES is a neutrino telescope being deployed in the Mediterranean Sea. It consists of a three dimensional array of photomultiplier tubes that can detect the Cherenkov light induced by charged particles produced in the interactions of neutrinos with the surrounding medium. High angular resolution can be achieved, in particular when a muon is produced, provided that the Cherenkov photons are detected with sufficient timing precision. Considerations of the intrinsic time uncertainties stemming from the transit time spread in the photomultiplier tubes and the mechanism of transmission of light in sea water lead to the conclusion that a relative time accuracy of the order of 0.5 ns is desirable. Accordingly, different time calibration systems have been developed for the ANTARES telescope. In this article, a system based on Optical Beacons, a set of external and well-controlled pulsed light sources located throughout the detector, is described. This calibration system takes into account the optical properties of sea water, which is used as the detection volume of the ANTARES telescope. The design, tests, construction and first results of the two types of beacons, LED and laser-based, are presented.Comment: 21 pages, 18 figures, submitted to Nucl. Instr. and Meth. Phys. Res.

Invasion syndromes: a systematic approach for predicting biological invasions and facilitating effective management

Published: 02 March 2020Our ability to predict invasions has been hindered by the seemingly idiosyncratic context-dependency of individual invasions. However, we argue that robust and useful generalisations in invasion science can be made by considering “invasion syndromes” which we define as “a combination of pathways, alien species traits, and characteristics of the recipient ecosystem which collectively result in predictable dynamics and impacts, and that can be managed effectively using specific policy and management actions”. We describe this approach and outline examples that highlight its utility, including: cacti with clonal fragmentation in arid ecosystems; small aquatic organisms introduced through ballast water in harbours; large ranid frogs with frequent secondary transfers; piscivorous freshwater fishes in connected aquatic ecosystems; plant invasions in high-elevation areas; tall-statured grasses; and tree-feeding insects in forests with suitable hosts. We propose a systematic method for identifying and delimiting invasion syndromes. We argue that invasion syndromes can account for the context-dependency of biological invasions while incorporating insights from comparative studies. Adopting this approach will help to structure thinking, identify transferrable risk assessment and management lessons, and highlight similarities among events that were previously considered disparate invasion phenomena.Ana Novoa, David M. Richardson, Petr Pyšek, Laura A. Meyerson, Sven Bacher ... Jasmin Packer ... et al

Measurement of W Polarisation at LEP

The three different helicity states of W bosons produced in the reaction e+ e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to measure the polarisation of W bosons, and its dependence on the W boson production angle. The fraction of longitudinally polarised W bosons is measured to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model expectation

Measurement of W Polarisation at LEP

The three different helicity states of W bosons produced in the reaction e+ e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to measure the polarisation of W bosons, and its dependence on the W boson production angle. The fraction of longitudinally polarised W bosons is measured to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and the second systematic, in agreement with the Standard Model expectation

Study of the e+e- -> Ze+e- process at LEP

The cross section of the process e+e- -> Ze+e is measured with 0.7fb^-1 of data collected with the L3 detector at LEP. Decays of the Z boson into quarks and muons are considered at centre-of-mass energies ranging from 183GeV up to 209GeV. The measurements are found to agree with Standard Model predictions, achieving a precision of about 10% for the hadronic channel

Lambda and Sigma0 Pair Production in Two-Photon Collisions at LEP

Strange baryon pair production in two-photon collisions is studied with the L3 detector at LEP. The analysis is based on data collected at e+e- centre-of-mass energies from 91 GeV to 208 GeV, corresponding to an integrated luminosity of 844 pb-1. The processes gamma gamma -> Lambda Anti-lambda and gamma gamma -> Sigma0 Anti-sigma0 are identified. Their cross sections as a function of the gamma gamma centre-of-mass energy are measured and results are compared to predictions of the quark-diquark model

Bose-Einstein Correlations of Neutral and Charged Pions in Hadronic Z Decays

Bose-Einstein correlations of both neutral and like-sign charged pion pairs are measured in a sample of 2 million hadronic Z decays collected with the L3 detector at LEP. The analysis is performed in the four-momentum difference range 300 MeV < Q < 2 GeV. The radius of the neutral pion source is found to be smaller than that of charged pions. This result is in qualitative agreement with the string fragmentation model