Myopic Loss Aversion, Asymmetric Correlations, and the Home Bias

Myopic loss aversion has been used to explain why a high equity premium might be consistent with plausible levels of risk aversion. The intuition is that it plays the role of high risk aversion in portfolio choice. But if so, should these agents not perceive larger gains from international diversification than standard preference agents with realistic levels of risk aversion? They might not because stock market returns are asymmetrically correlated. We analyze the portfolio problem of a myopic loss averse investor who has to choose between home and foreign equities in the presence of asymmetrically correlated returns. Perhaps surprisingly, depending on the horizon, this investor behaves similarly to one with standard preferences in the context of the home bias puzzlemyopic loss aversion, home bias, asymmetric correlations, equity premium puzzle

A common garden design reveals population-specific variability in potential impacts of hybridisation between populations of farmed and wild Atlantic salmon, Salmo salar L

Released individuals can have negative impacts on native populations through various mechanisms; including competition, disease transfer and introduction of maladapted gene-complexes. Previous studies indicate that the level of farmed Atlantic salmon introgression in native populations is population-specific. However few studies have explored the potential role of population diversity or river characteristics, such as temperature, on the consequences of hybridisation. We compared freshwater growth of multiple families derived from two farmed, five wild, and two F1 hybrid salmon populations at three contrasting temperatures (7°C, 12°C, and 16°C) in a common garden experiment. As expected, farmed salmon outgrew wild salmon at all temperatures, with hybrids displaying intermediate growth. However, differences in growth were population-specific and some wild populations performed better than others relative to the hybrid and farmed populations at certain temperatures. Therefore, the competitive balance between farmed and wild salmon may depend both on the thermal profile of the river and the genetic characteristics of the respective farmed and wild strains. While limited to F1 hybridisation, the present study shows the merits in adopting a more complex spatially resolved approach to risk management of local populations

Automatically identifying ordinary differential equations from data

Discovering nonlinear differential equations that describe system dynamics from empirical data is a fundamental challenge in contemporary science. Here, we propose a methodology to identify dynamical laws by integrating denoising techniques to smooth the signal, sparse regression to identify the relevant parameters, and bootstrap confidence intervals to quantify the uncertainty of the estimates. We evaluate our method on well-known ordinary differential equations with an ensemble of random initial conditions, time series of increasing length, and varying signal-to-noise ratios. Our algorithm consistently identifies three-dimensional systems, given moderately-sized time series and high levels of signal quality relative to background noise. By accurately discovering dynamical systems automatically, our methodology has the potential to impact the understanding of complex systems, especially in fields where data are abundant, but developing mathematical models demands considerable effort

Dual-pumped degenerate Kerr oscillator in a silicon nitride microresonator

We demonstrate a degenerate parametric oscillator in a silicon-nitride microresonator. We use two frequency-detuned pump waves to perform parametric four-wave mixing and operate in the normal group-velocity dispersion regime to produce signal and idler fields that are frequency degenerate. Our theoretical modeling shows that this regime enables generation of bimodal phase states, analogous to the \c{hi}(2)-based degenerate OPO. Our system offers potential for realization of CMOS-chip-based coherent optical computing and an all-optical quantum random number generator

Pre-stimulus antero-posterior EEG connectivity predicts performance in a UAV monitoring task

Long monitoring tasks without regular actions, are becoming increasingly common from aircraft pilots to train conductors as these systems grow more automated. These task contexts are challenging for the human operator because they require inputs at irregular and highly interspaced moments even though these actions are often critical. It has been shown that such conditions lead to divided and distracted attentional states which in turn reduce the processing of external stimuli (e.g. alarms) and may lead to miss critical events. In this study we explored to which extent it is possible to predict an operator’s behavioural performance in a Unmanned Aerial Vehicle (UAV) monitoring task using electroencephalographic (EEG) activity. More specifically we investigated the relevance of large-scale EEG connectivity for performance prediction by correlating relative coherence with reaction times (RT). We show that long-range EEG relative coherence, i.e. between occipital and frontal electrodes, is significantly correlated with RT and that different frequency bands exhibit opposite effects. More specifically we observed that coherence between occipital and frontal electrodes was: negatively correlated with RT at 6Hz (theta band), more coherence leading to better performance, and positively correlated with RT at 8Hz (lower alpha band), more coherence leading to worse performance. Our results suggest that EEG connectivity measures could be useful in predicting an operator’s attentional state and her/his performances in ecological settings. Hence these features could potentially be used in a neuro-adaptive interface to improve operator-system interaction and safety in critical systems

Actin polymerization or myosin contraction: two ways to build up cortical tension for symmetry breaking

International audienceCells use complex biochemical pathways to drive shape changes for polarization and movement. One of these pathways is the self-assembly of actin filaments and myosin motors that together produce the forces and tensions that drive cell shape changes. Whereas the role of actin and myosin motors in cell polarization is clear, the exact mechanism of how the cortex, a thin shell of actin that is underneath the plasma membrane, can drive cell shape changes is still an open question. Here, we address this issue using biomimetic systems: the actin cortex is reconstituted on liposome membranes, in an 'outside geometry'. The actin shell is either grown from an activator of actin polymeriz-ation immobilized at the membrane by a biotin–streptavidin link, or built by simple adsorption of biotinylated actin filaments to the membrane, in the presence or absence of myosin motors. We show that tension in the actin network can be induced either by active actin polymerization on the membrane via the Arp2/3 complex or by myosin II filament pulling activity. Symmetry breaking and spontaneous polarization occur above a critical tension that opens up a crack in the actin shell. We show that this critical tension is reached by growing branched networks, nucleated by the Arp2/3 complex, in a concentration window of capping protein that limits actin filament growth and by a sufficient number of motors that pull on actin filaments. Our study provides the groundwork to understanding the physical mechanisms at work during polarization prior to cell shape modifications

Can diagnostic tests help identify model misspecification in integrated stock assessments?

AbstractA variety of data types can be included in contemporary integrated stock assessments to simultaneously provide information on all estimated parameters. Conflicts between data, which are often a symptom of model misspecification and evident as model misfit, can affect the estimates of important parameters and derived quantities. Unfortunately, there are few standard diagnostic tools available for integrated stock assessment models that can provide the analyst with all the information needed to determine if there is substantial model misspecification. In this study, we use simulation methods to evaluate the ability of commonly-used and recently-proposed diagnostic tests to detect model misspecification in the observation model process (i.e., the incorrect form for survey selectivity), systems dynamics (i.e., incorrect assumed values for steepness of the stock-recruitment relationship and natural mortality), and incorrect data weighting. The diagnostic tests evaluated here were: i) residuals analysis (SDNR and runs test); ii) retrospective analysis; iii) the R0 likelihood component profile; iv) the age-structured production model (ASPM); and v) catch-curve analysis (CCA). The efficacy of the diagnostic tests depended on whether the misspecification was in the observation or systems dynamics model. Residual analyses were easily the best detector of misspecification of the observation model while the ASPM test was the only good diagnostic for detecting misspecification of system dynamics model. Retrospective analysis and the R0 likelihood component profile infrequently detected misspecified models, and CCA had a high probability of rejecting correctly-specified models. Finally, applying multiple carefully selected diagnostics can increase the power to detect misspecification without substantially increasing the probability of falsely concluding there is misspecification when the model is correctly specified

A quadruplex qPCR for detection and differentiation of classic and natural recombinant Myxoma Virus Strains of leporids

Research Areas: Biochemistry & Molecular Biology ; ChemistryA natural recombinant myxoma virus (referred to as ha-MYXV or MYXV-Tol08/18) emerged in the Iberian hare (Lepus granatensis) and the European rabbit (Oryctolagus cuniculus) in late 2018 and mid-2020, respectively. This new virus is genetically distinct from classic myxoma virus (MYXV) strains that caused myxomatosis in rabbits until then, by acquiring an additional 2.8 Kbp insert within the m009L gene that disrupted it into ORFs m009L-a and m009L-b. To distinguish ha-MYXV from classic MYXV strains, we developed a robust qPCR multiplex technique that combines the amplification of the m000.5L/R duplicated gene, conserved in all myxoma virus strains including ha-MYXV, with the amplification of two other genes targeted by the real-time PCR systems designed during this study, specific either for classic MYXV or ha-MYXV strains. The first system targets the boundaries between ORFs m009L-a and m009L-b, only contiguous in classic strains, while the second amplifies a fragment within gene m060L, only present in recombinant MYXV strains. All amplification reactions were validated and normalized by a fourth PCR system directed to a housekeeping gene (18S rRNA) conserved in eukaryotic organisms, including hares and rabbits. The multiplex PCR (mPCR) technique described here was optimized for Taqman® and Evagreen® systems allowing the detection of as few as nine copies of viral DNA in the sample with an efficiency > 93%. This real-time multiplex is the first fast method available for the differential diagnosis between classic and recombinant MYXV strains, also allowing the detection of co-infections. The system proves to be an essential and effective tool for monitoring the geographical spread of ha-MYXV in the hare and wild rabbit populations, supporting the management of both species in the field.info:eu-repo/semantics/publishedVersio

Laser Ablation of Electrode to Extend RSW Electrode Life and Save Production Cost

This invention presents an RSW electrode cost saving solution for resistance spot welding of aluminums, including apparatus with automation, ablation process and method. It is achieved by cleaning with a laser ablation process that minimizes the metal removal amount each time compared to a current mechanical electrode dressing method (Laser ablation 0.02mm vs electrode dressing 0.2mm). To make it effective and reproductive, the laser ablation process is preferably performed on the welding electrode prior to serious electrode sticking. RSW on various aluminum grades and joint stacks have been tested and validated in a lab scale, it has shown that the electrode life with laser ablation lasts at least 10 times longer in total than that of current electrode dressing method