Decision-rule cascades and the dynamics of speculative bubbles

We combine Minsky's financial fragility analysis, behavioural analysis of decision rules and the evolutionary economics of rule trajectories to provide an empirically grounded and computationally tractable theory of the complex evolutionary dynamics of speculative financial upswings. The behavioural dynamics of asset bubbles can be conceptualized as the joint consequence of the adoption and diffusion process of new investment decision rules coupled with the degradation of those rules as they pass from a few expert investors to larger population of amateurs. We illustrate this using data covering the recent Brisbane property market bubble (1999-2003) and show how it is consistent with the existence of such cascading decision rules. We then explain how multi-agent simulation methods can be used for modelling decision rule cascades. (c) 2006 Elsevier B.V. All rights reserved

Identification and pathogenicity of Alternaria species associated with leaf blotch disease and premature defoliation in French apple orchards

Leaf blotch caused by Alternaria spp. is a common disease in apple-producing regions. The disease is usually associated with one phylogenetic species and one species complex, Alternaria alternata and the Alternaria arborescens species complex (A. arborescens SC), respectively. Both taxa may include the Alternaria apple pathotype, a quarantine or regulated pathogen in several countries. The apple pathotype is characterized by the production of a host-selective toxin (HST) which is involved in pathogenicity towards the apple. A cluster of genes located on conditionally dispensable chromosomes (CDCs) is involved in the production of this HST (namely AMT in the case of the apple pathotype). Since 2016, leaf blotch and premature tree defoliation attributed to Alternaria spp. have been observed in apple-producing regions of central and south-eastern France. Our study aimed to identify the Alternaria species involved in apple tree defoliation and assess the presence of the apple pathotype in French orchards. From 2016 to 2018, 166 isolates were collected and identified by multi-locus sequence typing (MLST). This analysis revealed that all these French isolates belonged to either the A. arborescens SC or A. alternata. Specific PCR detection targeting three genes located on the CDC did not indicate the presence of the apple pathotype in France. Pathogenicity was assessed under laboratory conditions on detached leaves of Golden Delicious and Gala apple cultivars for a representative subset of 28 Alternaria isolates. All the tested isolates were pathogenic on detached leaves of cultivars Golden Delicious and Gala, but no differences were observed between the pathogenicity levels of A. arborescens SC and A. alternata. However, the results of our pathogenicity test suggest that cultivar Golden Delicious is more susceptible than Gala to Alternaria leaf blotch. Implications in the detection of the Alternaria apple pathotype and the taxonomic assignment of Alternaria isolates involved in Alternaria leaf blotch are discussed

Identification of effectors from the apple scab fungus Venturia Inaequalis

Submission note: This thesis is submitted in total fulfilment of the requirement of the degree of Doctor of Philosophy to the School of Life Sciences, Department of Animal, Plant and Soil Sciences, La Trobe University, Bundoora

Point-of-use Printed Nitrate Sensor With Desalination Units

Nitrate is an important marker of water quality that can be challenging to detect in seawater due to the presence of multiple chemical interferants and high background chloride. Here, we demonstrate a compact microfluidic device that incorporates electrochemical desalination to selectively remove the interfering chloride ions and improve the detection limit of the downstream potentiometric nitrate sensor. The microfluidic platform was fabricated by a low-cost cut-and-lamination approach, and the detection mechanism was based on potentiometric measurements at an Ag/AgCl electrode coated with a nitrate-selective membrane. The sensor system achieved a detection limit of 0.5 mM with a sensitivity of 11.3 mV/dec under continuous flow

Point-of-use printed nitrate sensor with desalination units.

Nitrate is an important marker of water quality that can be challenging to detect in seawater due to the presence of multiple chemical interferants and high background chloride. Here, we demonstrate a compact microfluidic device that incorporates electrochemical desalination to selectively remove the interfering chloride ions and improve the detection limit of the downstream potentiometric nitrate sensor. The microfluidic platform was fabricated by a low-cost cut-and-lamination approach, and the detection mechanism was based on potentiometric measurements at an Ag/AgCl electrode coated with a nitrate-selective membrane. The sensor system achieved a detection limit of 0.5 mM with a sensitivity of 11.3 mV/dec under continuous flow

A Sensor Array for the Ultrasensitive Discrimination of Heavy Metal Pollutants in Seawater

Metal cations are potent environmental pollutants that negatively impact human health and the environment. Despite advancements in sensor design, the simultaneous detection and discrimination of multiple heavy metals at sub-nanomolar concentrations in complex analytical matrices remain a major technological challenge. Here, the design, synthesis, and analytical performance of three highly emissive conjugated polyelectrolytes (CPEs) functionalized with strong iminodiacetate and iminodipropionate metal chelates that operate in challenging environmental samples such as seawater are demonstrated. When coupled with array-based sensing methods, these polymeric sensors discriminate among nine divalent metal cations (CuII, CoII, NiII, MnII, FeII, ZnII, CdII, HgII, and PbII). The unusually high and robust luminescence of these CPEs enables unprecedented sensitivity at picomolar concentrations in water. Unlike previous array-based sensors for heavy metals using CPEs, the incorporation of distinct π-spacer units within the polymer backbone affords more pronounced differences in each polymer\u27s spectroscopic behavior upon interaction with each metal, ultimately producing better analytical information and improved differentiation. To demonstrate the environmental and biological utility, a simple two-component sensing array is showcased that can differentiate nine metal cation species down to 500 × 10−12 m in aqueous media and to 100 × 10−9 m in seawater samples collected from the Gulf of Mexico

Dual-Gate Organic Electrochemical Transistors for Marine Sensing

Monitoring dissolved oxygen is essential to marine research, but the high redox potentials required to drive sensing reactions have posed an ongoing instability issue in the sensors. Here, a novel dual-gate configuration for organic electrochemical transistors that extends the device electrochemical stability window is demonstrated. This paper presents the sensor operating principle that relates the channel conductance to potentials on the two gates. This broadly applicable design allows a large potential to be applied between the gates for sensing analytes, while synergistically modulating the channel within a lower potential range to maintain the stability of the semiconductor. Specifically, the sensor achieves a detection limit of 0.3 ppm dissolved oxygen concentration in seawater, with a sensitivity of 222 µA cm−2 ppm−1 for concentrations below 5 ppm. The device demonstrates reliable operation over 5 days and is capable of monitoring oxygenation changes arising from the photosynthesis cycles of saltwater macro-algae. This dual-gate configuration serves to extend the sensor operating voltage window and improves device stability. Thus, this new configuration provides a new type of compact, robust sensor for marine research, and opportunities in other fields ranging from waste-water management to bioelectronics