172 research outputs found
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Get PDFDetecting pathogens and mounting immune responses upon infection is crucial for animal health. However, these responses come at a high metabolic price (McKean and Lazzaro, 2011, Kominsky et al., 2010), and avoiding pathogens before infection may be advantageous. The bacterial endotoxins lipopolysaccharides (LPS) are important immune system infection cues (Abbas et al., 2014), but it remains unknown whether animals possess sensory mechanisms to detect them prior to infection. Here we show that Drosophila melanogaster display strong aversive responses to LPS and that gustatory neurons expressing Gr66a bitter receptors mediate avoidance of LPS in feeding and egg laying assays. We found the expression of the chemosensory cation channel dTRPA1 in these cells to be necessary and sufficient for LPS avoidance. Furthermore, LPS stimulates Drosophila neurons in a TRPA1-dependent manner and activates exogenous dTRPA1 channels in human cells. Our findings demonstrate that flies detect bacterial endotoxins via a gustatory pathway through TRPA1 activation as conserved molecular mechanism.sponsorship: Vlaams Instituut voor Biotechnologie Alessia Soldano Luis Franco Guangda Liu Natalia Mora Emre Yaksi Bassem A Hassanr Fonds Wetenschappelijk Onderzoek G.0702.12 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0077.15 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0680.10 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0681.10 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0503.12 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0654.15 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0761.10N Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0596.12 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar Fonds Wetenschappelijk Onderzoek G.0565.07 Alessia Soldano Yeranddy A Alpizar Brett Boonen Alejandro Lopez-Requena Natalia Mora Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar KU Leuven GOA/14/011 Alessia Soldano Yeranddy A Alpizar Brett Boonen Luis Franco Alejandro Lopez-Requena Guangda Liu Natalia Mora Emre Yaksi Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar European Commission IUAP P7/13 Alessia Soldano Yeranddy A Alpizar Brett Boonen Luis Franco Alejandro Lopez-Requena Guangda Liu Natalia Mora Emre Yaksi Thomas Voets Rudi Vennekensr KU Leuven OT/12/091 Alessia Soldano Yeranddy A Alpizar Brett Boonen Luis Franco Alejandro Lopez-Requena Guangda Liu Natalia Mora Emre Yaksi Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talaverar KU Leuven PF-TRPLe Alessia Soldano Yeranddy A Alpizar Brett Boonen Luis Franco Alejandro Lopez-Requena Guangda Liu Natalia Mora Emre Yaksi Thomas Voets Rudi Vennekens Bassem A Hassan Karel Talavera (Vlaams Instituut voor Biotechnologie, Fonds Wetenschappelijk Onderzoek|G.0702.12, Fonds Wetenschappelijk Onderzoek|G.0077.15, Fonds Wetenschappelijk Onderzoek|G.0680.10, Fonds Wetenschappelijk Onderzoek|G.0681.10, Fonds Wetenschappelijk Onderzoek|G.0503.12, Fonds Wetenschappelijk Onderzoek|G.0654.15, Fonds Wetenschappelijk Onderzoek|G.0761.10N, Fonds Wetenschappelijk Onderzoek|G.0596.12, KU Leuven|GOA/14/011, KU Leuven|OT/12/091, European Commission|IUAP P7/13, KU Leuven PF-TRPLe)status: Publishe
Volatile allocations
Get PDFTim Boonen discusses the pitfalls of the Euler rule for capital allocation and proposes an alternative
Heroes in the sports pages: the troubled road to victory for Belgian cyclist Tom Boonen
No full textConcepts such as myth and archetype offer interesting opportunities for research on media content. Both concepts, however, have very diffuse definitions and operationalizations stemming from specific fields of application. As a result, the concepts of myth and archetype have proved difficult to translate into a transparent and replicable research design to study journalistic output. This paper aims at a thorough operationalization of the hero myth/archetype. The hero archetype will be explored in detail as it is one of the most common archetypal narratives. The archetypal hero journey is translated by developing an operational hero grid in which the archetypal hero narrative is classified in nine sequences and three constituent components. The Flemish press coverage of cyclist Tom Boonen is analyzed to test empirically the developed research tool. While the emphasis of this paper lies on the empirical testing of this research tool, it also aims to broaden empirical data on the coverage of sport figures in the press. Results clearly show myth at work in the newspaper reporting on Tom Boonen
On the existence of a representative reinsurer under heterogeneous beliefs
Get PDFThis paper studies a one-period optimal reinsurance design model with n reinsurers and an insurer. The reinsurers are endowed with expected-value premium principles and with heterogeneous beliefs regarding the underlying distribution of the insurer’s risk. Under general preferences for the insurer, a representative reinsurer is characterized. This means that all reinsurers can be treated collectively by means of a hypothetical premium principle in order to determine the optimal total risk that is ceded to all reinsurers. The optimal total ceded risk is then allocated to the reinsurers by means of an explicit solution. This is shown both in the general case and under the no-sabotage condition that avoids possible ex post moral hazard on the side of the insurer, thereby extending the results of Boonen et al. (2016). We subsequently derive closed-form optimal reinsurance contracts in case the insurer maximizes expected net wealth. Moreover, under the no-sabotage condition, we derive optimal reinsurance contracts in case the insurer maximizes dual utility, or in case the insurer maximizes a generic objective that preserves second-order stochastic dominance under the assumption of a monotone hazard ratio
Bowley reinsurance with asymmetric information: A first-best solution
No full textBowley reinsurance solutions are reinsurance contracts for which the reinsurer optimally sets the pricing density while anticipating that the insurer will choose the optimal reinsurance indemnity given this pricing density. This Bowley solution concept of equilibrium reinsurance strategy has been revisited in the modern risk management framework by Boonen et al. [(2021). Bowley reinsurance with asymmetric information on the insurer's risk preferences. Scandinavian Actuarial Journal 2021 , 623–644], where the insurer and reinsurer are both endowed with distortion risk measures but there is asymmetric information on the distortion risk measure of the insurer. In this article, we continue to study this framework, but we allow the premium principle to be more flexible. We call this solution the first-best Bowley solution. We provide first-best Bowley solutions in closed form under very general assumptions. We implement some numerical examples to illustrate the findings and the comparisons with the second-best solution. The main result is further extended to the case when both the reinsurer and the insurers have heterogeneous beliefs on the distribution functions of the underlying risk
Equilibria and efficiency in a reinsurance market
No full textWe study equilibria in a reinsurance market with multiple reinsurers that are endowed with heterogeneous beliefs, where preferences are given by distortion risk measures, and pricing is done via Choquet integrals. We construct a model in the form of a sequential economic game, where the reinsurers have the first-mover advantage over the insurer, as in the Stackelberg setting. However, unlike the Stackelberg setting, which assumes a single monopolistic reinsurer on the supply side, our model accounts for strategic price competition between reinsurers. We argue that the notion of a Subgame Perfect Nash Equilibrium (SPNE) is the appropriate solution concept for analyzing equilibria in the reinsurance market, and we characterize SPNEs using a set of sufficient conditions. We then examine efficiency properties of the contracts induced by an SPNE, and show that these contracts result in Pareto-efficient allocations. Additionally, we show that under mild conditions, the insurer realizes a strict welfare gain, which addresses the concerns of Boonen and Ghossoub (2022) with the Stackelberg model and thereby ultimately reflects the benefit to the insurer of competition on the supply side. We illustrate this point with a numerical example.</p
UvA-DARE (Digital Academic Repository) Redistribution of Longevity Risk: The effect of heterogeneous mortality beliefs *
Get PDFRedistribution of longevity risk: The effect of heterogeneous mortality beliefs Boonen, T.J.; De Waegenaere, A.; Norde, H. General rights It is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulations If you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: https://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. Abstract Existing literature regarding the natural hedge potential that arises from combining different longevity-linked liabilities typically does not address the question how changes in the liability mix can be obtained. We consider firms who aim to exploit the benefits of natural hedge potential by redistributing their risks, and characterize the risk redistributions that will arise when the parties bargain for a redistribution of risk that weakly benefits them all. We analyze the effects of heterogeneity in the beliefs regarding the probability distribution of future mortality rates on the properties of these risk redistributions, and provide a numerical illustration for a case where an insurer with a portfolio of term assurance contracts and a pension fund with a portfolio of life annuities redistribute their risks. JEL-Classification: C71, C78, G22, J1
Optimal reinsurance with heterogeneous reference probabilities
Get PDFThis paper studies the problem of optimal reinsurance contract design. We let the insurer use dual utility, and the premium is an extended Wang’s premium principle. The novel contribution is that we allow for heterogeneity in the beliefs regarding the underlying probability distribution. We characterize layer-reinsurance as an optimal reinsurance contract. Moreover, we characterize layer-reinsurance as optimal contracts when the insurer faces costs of holding regulatory capital. We illustrate this in cases where both firms use the Value-at-Risk or the conditional Value-at-Ris
Solvency II Solvency Capital Requirement for life insurance companies based on Expected Shortfall
Get PDFThis paper examines the consequences for a life annuity insurance company if the solvency II solvency capital requirements (SCR) are calibrated based on expected shortfall (ES) instead of value-at-risk (VaR). We focus on the risk modules of the SCRs for the three risk classes equity risk, interest rate risk and longevity risk. The stress scenarios are determined using the calibration method proposed by EIOPA in 2014. We apply the stress-scenarios for these three risk classes to a fictitious life annuity insurance company. We find that for EIOPA’s current quantile 99.5% of the VaR, the stress scenarios of the various risk classes based on ES are close to the stress scenarios based on VaR. Might EIOPA choose to calibrate the stress scenarios on a smaller quantile, the longevity SCR is relatively larger and the equity SCR is relatively smaller if ES is used instead of VaR. We derive the same conclusion if stress scenarios are determined with empirical stress scenarios
A discussion of ’Optimal reinsurance designs based on risk measures: A review’
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