News and price returns from threshold behaviour and vice-versa: exact solution of a simple agent-based market model

Starting from an exact relationship between news, threshold and price return distributions in the stationary state, I discuss the ability of the Ghoulmie-Cont-Nadal model of traders to produce fat-tailed price returns. Under normal conditions, this model is not able to transform Gaussian news into fat-tailed price returns. When the variance of the news so small that only the players with zero threshold can possibly react to news, this model produces Levy-distributed price returns with a -1 exponent. In the special case of super-linear price impact functions, fat-tailed returns are obtained from well-behaved news.Comment: 4 pages, 3 figures. This is quite possibly the final version. To appear in J. Phys

Exceeding the threshold value for Trioza apicalis Förster 1848 in carrot fields did not cause damage as revealed during monitoring in Germany from 2017–2020

The carrot psyllid Trioza apicalis Förster 1848 is a carrot pest in Europe that can cause serious damages in case of massive occurrence. Damages up to a total loss of yield have been reported from Scandinavian countries but also from Switzerland. The action threshold to control the pest with chemical pesticides is 0.2 T. apicalis per day and trap caught by sticky traps. We investigated the number of T. apicalis with sticky traps on carrot fields of the study regions Lüneburg/Uelzen and Hameln/Bad Pyrmont in Germany, during the period 2017–2020. The number of T. apicalis caught was generally very low in both study regions. On several fields in successive weeks almost no individuals were found in the study region Hameln/Bad Pyrmont. In Lüneburg/Uelzen was at least one field each year where the number of carrot psyllid was clearly higher than in all other fields and exceeded the threshold level. Surprisingly on carrot fields in close proximity to carrot fields from the previous year, the T. apicalis numbers were only slightly increased. Nonetheless, no loss of yield was reported for any of the fields in the four years of the study, although the generally defined threshold has been exceeded on many of the investigated carrot fields

Dynamical instabilities in a simple minority game with discounting

We explore the effect of discounting and experimentation in a simple model of interacting adaptive agents. Agents belong to either of two types and each has to decide whether to participate a game or not, the game being profitable when there is an excess of players of the other type. We find the emergence of large fluctuations as a result of the onset of a dynamical instability which may arise discontinuously (increasing the discount factor) or continuously (decreasing the experimentation rate). The phase diagram is characterized in detail and noise amplification close to a bifurcation point is identified as the physical mechanism behind the instability.Comment: 8 page

The adaptiveness in stock markets: testing the stylized facts in the DAX 30

© 2017, Springer-Verlag Berlin Heidelberg. By testing a simple asset pricing model of heterogeneous agents to characterize the power-law behavior of the DAX 30 from 1975 to 2007, we provide supporting evidence on empirical findings that investors and fund managers use combinations of fixed and switching strategies based on fundamental and technical analysis when making investment decisions. A mechanism analysis based on the calibrated model provides a behavioral insight into the explanatory power of rational switching behavior of investors on the volatility clustering and long range dependence in return volatility

Extracts of Feijoa Inhibit Toll-Like Receptor 2 Signaling and Activate Autophagy Implicating a Role in Dietary Control of IBD

Inflammatory bowel disease (IBD) is a heterogeneous chronic inflammatory disease affecting the gut with limited treatment success for its sufferers. This suggests the need for better understanding of the different subtypes of the disease as well as nutritional interventions to compliment current treatments. In this study we assess the ability of a hydrophilic feijoa fraction (F3) to modulate autophagy a process known to regulate inflammation, via TLR2 using IBD cell lines