Miljoenenjacht: voer voor economen

Onderzoek naar de risicohouding van deelnemers aan Miljoenenjacht laat zien dat ‘pech in het spel’ deelnemers minder gevoelig maakt voor risico’s. De echte pechvogels accepteren zelfs ‘oneerlijke’ kansspelen. Psychologie lijkt belangrijker te zijn dan veel economen denken

Deal or No Deal? Decision-making under Risk in a Large-payoff Game Show

The popular television game show deal or No Deal offers a unique opportunity for analyzing decision making under risk: it involves very large stakes, simple take-or-leave decisions that require minimal skill or strategy and near-certainty about the probability distribution. Based on a panel data set of the choices of contestants in all game rounds of 53 episodes from Australia and the Netherlands, we find an average Pratt-Arrow relative risk aversion (RRA) between roughly 1 and 2 for initial wealth levels between 0 and 50,000. The RRA differs substantially across the contestants and some even exhibit risk seeking behavior. The cross-sectional differences in RRA can be explained in large part by the previous outcomes experienced by the contestants during the game. Most notably, consistent with the break-even effect,the RRA strongly decreases following earlier losses and risk seeking arises after large losses.To be published in American Economic Revie

Evidencia serológica de infección por Neospora caninum en rebaños lecheros del Sur de Chile

Neospora caninum is a recently recognised parasite that produces infection in dogs and herbivorous. In cows, the disease does not produce clinical signs of illness, instead it produces losses. Chile has a large dairy industry and pregnancy losses in that system seem to be economically important. However a large number of abortions remain with unknown aetiology and abortion due to protozoa has not been investigated. We report here, for the first time, that aborted cows belonging to three different farms in the IX Region, Chile had antibodies to N. Caninumis given here. The episode of abortion was "sporadic" and occurred in adult cows. The sera were diluted in 1:200 and processed with the Neospora IFA test. Whole tachyzoite surface fluorescent was considered positive. Aantibodies were found in 10 of 21 adult cows, none of 2 heifers and 1 of 6 calves in farm A. In farm B, they were found in 7 of 24 adult cows and in 2 of 2 adult cows of farm C. All the aborted cows (2 on farm A; 3 aborted and 1 mummified on farm B; and 2 on farm C) were positive to the test. Taking into consideration the IFA test results and the negativity of serology to other common infections which cause bovine abortion, the hypothesis that these cows aborted due to Neospora infection is supported. How the disease has spread world wide is unknown, but most probably, international animal trade has contributed to help spread the disease. Before any recommendation can be made more extensive studies should be done in order to establish the prevalence and the economic impact of the disease. At the moment evidence that Neospora infection is already present in this country is presented. Therefore it should be included as a differential diagnosis of bovine abortion.Los abortos bovinos causan importantes pérdidas económicas a la ganadería mundial. Una parte importante de ellos permanecen aún con etiología desconocida, y de los diagnosticados, la mayoría corresponden a causas infecciosas. Dentro de ellos los abortos ocasionados por protozoos han tomado relevancia mundial. En Chile hasta ahora se desconocía su presencia. En este trabajo se presenta evidencia que vacas con antecedentes de abortos presentaron anticuerpos contra N. caninum detectados mediante la técnica IFA y se discute la posibilidad de que hayan ocurrido como consecuencia de la infección por este protozo

Random incentive systems in a dynamic choice experiment

Experiments frequently use a random incentive system (RIS), where only tasks that are randomly selected at the end of the experiment are for real. The most common type pays every subject one out of her multiple tasks (within-subjects randomization). Recently, another type has become popular, where a subset of subjects is randomly selected, and only these subjects receive one real payment (between-subjects randomization). In earlier tests with simple, static tasks, RISs performed well. The present study investigates RISs in a more complex, dynamic choice experiment. We find that between-subjects randomization reduces risk aversion. While within-subjects randomization delivers unbiased measurements of risk aversion, it does not eliminate carry-over effects from previous tasks. Both types generate an increase in subjects' error rates. These results suggest that caution is warranted when applying RISs to more complex and dynamic tasks

Chiral approach to the rho meson in nuclear matter

In this work, the properties of the $\rho$ meson at rest in cold symmetric nuclear matter are studied. We make use of a chiral unitary approach to pion-pion scattering in the vector-isovector channel, calculated from the lowest order Chiral Perturbation Theory ($\chi PT$) lagrangian including explicit resonance fields. Low energy chiral constraints are considered by matching our expressions to those of one loop $\chi PT$. To account for the medium corrections, the $\rho$ couples to $\pi\pi$ pairs which are properly renormalized in the nuclear medium, accounting for both $p-h$ and $\Delta -h$ excitations. The terms where the $\rho$ couples directly to the hadrons in the $p-h$ or $\Delta -h$ excitations are also accounted for. In addition, the $\rho$ is also allowed to couple to $N^{*}(1520)-h$ components.Comment: 30 pages, 20 figures, revised version. Additional sources of the rho selfenergy considered. Some references adde

Working definitions, subjective and objective assessments and experimental paradigms in a study exploring social withdrawal in schizophrenia and Alzheimer's disease

Social withdrawal is one of the first and common signs of early social dysfunction in a number of important neuropsychiatric disorders, likely because of the enormous amount and complexity of brain processes required to initiate and maintain social relationships (Adolphs, 2009). The Psychiatric Ratings using Intermediate Stratified Markers (PRISM) project focusses on the shared and unique neurobiological basis of social withdrawal in schizophrenia, Alzheimer and depression. In this paper, we discuss the working definition of social withdrawal for this study and the selection of objective and subjective rating scales to assess social withdrawal chosen or adapted for this project. We also discuss the MRI and EEG paradigms selected to study the systems and neural circuitry thought to underlie social functioning and more particularly to be involved in social withdrawal in humans, such as the social perception and the social affiliation networks. A number of behavioral paradigms were selected to assess complementary aspects of social cognition. Also, a digital phenotyping method (a smartphone application) was chosen to obtain real-life data.This work was supported by the European Union Horizon 2020 Innovative Medicines Initiative 2 Joint Undertaking grant 115916 for the project ‘Psychiatric ratings using intermediate stratified markers

Discrimination of intravascular lumen and dissections in single intravascular ultrasound images using subtraction, conventional averaging and saline flush

With current 30-MHz intravascular ultrasound systems, flowing blood may cause considerable backscatter which in real-time images is characterized by dynamic speckle. However, in a single intravascular ultrasound image (still-frame) the discrimination between arterial lumen and wall may be difficult due to the frozen intraluminal speckle, particularly in the presence of dissections. We compared subtraction, averaging and saline flush as methods to improve the discrimination between arterial lumen and wall in a single image. The real-time images served as gold standard. In 22 patients who underwent peripheral balloon angioplasty, ultrasound images obtained from 84 sites were examined. The sensitivity and specificity of detecting dissections were in the subtraction image 85% and 100%, in the averaged image 57% and 96%, and in the saline flush image 58% and 86%, respectively. Subtraction is a promising method to outline the irregular lumen in a single image

Shear-stress and wall-stress regulation of vascular remodeling after balloon angioplasty: effect of matrix metalloproteinase inhibition

BACKGROUND: Constrictive vascular remodeling (VR) is the most significant component of restenosis after balloon angioplasty (PTA). Whereas in physiologi