On the Evolutionary Emergence of Optimism

Successful individuals were frequently found to be overly optimistic. This is puzzling because it might be thought that optimistic individuals who consistently overestimate their eventual payoffs will not do as well as realists who see the situation as it truly is and hence will not survive evolutionary pressures. We show that contrary to this intuition, there is a large class of either competitive or cooperative strategic interactions between randomly matched pairs of individuals in the population, in which "cautiously" optimistic individuals not only survive but also prosper and take over the entire population. The reason for this result is that optimistic individuals who overestimate the impact of their actions on their payoffs, behave more aggressively than realists and pessimists. When the interactions between individuals involve negative externalities (the payoff of one player decreases with the actions taken by another player) and the actions are strategic substitutes, being aggressive induces the opponent to be softer, so optimists gain a strategic advantage that, for moderate levels of optimism, outweighs the loss from having the wrong perception of the environment. Likewise, when the interactions between individuals involve positive externalities and the actions are strategic complements, being aggressive triggers a favorable aggressive behavior from the opponent. Hence, in both cases, cautiously optimistic types fare better on average than other types of individuals. We show that if the initial distribution of types is sufficiently wide, then over time it will converge in distribution to a mass point on some level of cautious optimism.

Stock price dynamics: an application of the Ehrenfest-Brillouin model to the Italian stock exchange

openIn this thesis, the central point is the application of stock price dynamics of the Italian stock exchange, in the period between June 1973 and April 1998. Given the daily percentage returns, in order to estimate some other parameters, is useful to introduce the preliminary notions of Markov chains and Polya process, essential to understand the Ehrenfest-Brillouin model. This model is fundamental to the interpretation of a moving system of elements in some categories, and that can be applied, in particular, to price increments in a stock market.In this thesis, the central point is the application of stock price dynamics of the Italian stock exchange, in the period between June 1973 and April 1998. Given the daily percentage returns, in order to estimate some other parameters, is useful to introduce the preliminary notions of Markov chains and Polya process, essential to understand the Ehrenfest-Brillouin model. This model is fundamental to the interpretation of a moving system of elements in some categories, and that can be applied, in particular, to price increments in a stock market

Commonwealth Times 1978-09-19

https://scholarscompass.vcu.edu/com/1313/thumbnail.jp

On the possibility of stable regularities without fundamental laws

This doctoral dissertation investigates the notion of physical necessity. Specifically, it studies whether it is possible to account for non-accidental regularities without the standard assumption of a pre-existent set of governing laws. Thus, it takes side with the so called deflationist accounts of laws of nature, like the humean or the antirealist. The specific aim is to complement such accounts by providing a missing explanation of the appearance of physical necessity. In order to provide an explanation, I recur to fields that have not been appealed to so far in discussions about the metaphysics of laws. Namely, I recur to complex systems’ theory, and to the foundations of statistical mechanics. The explanation proposed is inspired by how complex systems’ theory has elucidated the way patterns emerge, and by the probabilistic explanations of the 2nd law of thermodynamics. More specifically, this thesis studies how some constraints that make no direct reference to the dynamics can be a sufficient condition for obtaining in the long run, with high probability, stable regular behavior. I hope to show how certain metaphysical accounts of laws might benefit from the insights achieved in these other fields. According to the proposal studied in this thesis, some regularities are not accidental not in virtue of an underlying physical necessity. The non-accidental character of certain regular behavior is only due to its overwhelming stability. Thus, from this point of view the goal becomes to explain the stability of temporal patterns without assuming a set of pre-existent guiding laws. It is argued that the stability can be the result of a process of convergence to simpler and stable regularities from a more complex lower level. According to this project, if successful, there would be no need to postulate a (mysterious) intermediate category between logical necessity and pure contingency. Similarly, there would be no need to postulate a (mysterious) set of pre-existent governing laws. Part I of the thesis motivates part II, mostly by arguing why further explanation of the notions of physical necessity and governing laws should be welcomed (chapter 1), and by studying the plausibility of a lawless fundamental level (chapters 2 and 3). Given so, part II develops the explanation of formation of simpler and stable behavior from a more complex underlying level

PariRandom : Entropy distribution in a p2p network

Current software entropy generators bring entropy to a level which is not always suitable for its final use. There is a particular trade-off between the quality of entropy and the speed needed to generate it. We propose a novel method to improve the quality of entropy generators that leverages the ever growing phenomenon of Peer-to-peer networks. PariRandom is a pseudo-random number generation system that may be used to extend all other existing Pseudo Random Number Generation (PRNG) algorithms, ensuring they have an equal or greater level of entropy. An important aspect of our system is that it does not noticeably increase the underlying traffic, "piggybacking" instead on packets that would be transmitted anyway. The theoretical and experimental results demonstrate an increase in performance, which on a wide-scale, comes close to the performance achieved by hardware entropy generators. Moreover, they guarantee resistance to every kind of attack by malicious nodes in the networ

Biosimilars in Europe

This reprint examines regulatory, pricing and reimbursement issues related to the market access and uptake of off-patent biologics, biosimilars, next-generation biologics and competing innovative medicines in European countries

New Game Physics - Added Value for Transdisciplinary Teams

This study focused on game physics, an area of computer game design where physics is applied in interactive computer software. The purpose of the research was a fresh analysis of game physics in order to prove that its current usage is limited and requires advancement. The investigations presented in this dissertation establish constructive principles to advance game physics design. The main premise was that transdisciplinary approaches provide significant value. The resulting designs reflected combined goals of game developers, artists and physicists and provide novel ways to incorporate physics into games. The applicability and user impact of such new game physics across several target audiences was thoroughly examined. In order to explore the transdisciplinary nature of the premise, valid evidence was gathered using a broad range of theoretical and practical methodologies. The research established a clear definition of game physics within the context of historical, technological, practical, scientific, and artistic considerations. Game analysis, literature reviews and seminal surveys of game players, game developers and scientists were conducted. A heuristic categorization of game types was defined to create an extensive database of computer games and carry out a statistical analysis of game physics usage. Results were then combined to define core principles for the design of unconventional new game physics elements. Software implementations of several elements were developed to examine the practical feasibility of the proposed principles. This research prototype was exposed to practitioners (artists, game developers and scientists) in field studies, documented on video and subsequently analyzed to evaluate the effectiveness of the elements on the audiences. The findings from this research demonstrated that standard game physics is a common but limited design element in computer games. It was discovered that the entertainment driven design goals of game developers interfere with the needs of educators and scientists. Game reviews exemplified the exaggerated and incorrect physics present in many commercial computer games. This “pseudo physics” was shown to have potentially undesired effects on game players. Art reviews also indicated that game physics technology remains largely inaccessible to artists. The principal conclusion drawn from this study was that the proposed new game physics advances game design and creates value by expanding the choices available to game developers and designers, enabling artists to create more scientifically robust artworks, and encouraging scientists to consider games as a viable tool for education and research. The practical portion generated tangible evidence that the isolated “silos” of engineering, art and science can be bridged when game physics is designed in a transdisciplinary way. This dissertation recommends that scientific and artistic perspectives should always be considered when game physics is used in computer-based media, because significant value for a broad range of practitioners in succinctly different fields can be achieved. The study has thereby established a state of the art research into game physics, which not only offers other researchers constructive principles for future investigations, but also provides much-needed new material to address the observed discrepancies in game theory and digital media design

Dynamic energy budgets and bioaccumulation : a model for marine mammals and marine mammal populations

Submitted to the Department of Biology in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Biological Oceanography at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2006Energy intake of individuals affects growth of organisms and, therefore, populations. Persistent lipophilic toxicants acquired with the energy can bioaccumulate and harm individuals. Marine mammals are particularly vulnerable because of their large energy requirements, and transfer of energy and toxicants from mothers to their young during gestation and lactation. Dynamic energy budget (DEB) models for energy assimilation and utilization, coupled with pharmacokinetic models that calculate distribution of toxicants in individuals, can help investigate the vulnerability. In this dissertation I develop the first individual DEB model tailored specifically to marine mammals and couple it to a pharmacokinetic model for lipophilic toxicants. I adapt the individual model to the right whale and use it to analyze consequences of energy availability on individual growth, reproduction, bioaccumulation, and transfer of toxicants between generations. From the coupled model, I create an individual-based model (IBM) of a marine mammal population. I use it to investigate how interactions of food availability, exposure to toxicants, and maternal transfer of toxicants affect populations. I also present a method to create matrix population models from a general DEB model to alleviate some of the drawbacks of the IBM approach.This work has been supported by the David and Lucile Packard Foundation, the US National Science foundation (DEB-9973518 and OCE-0083976), the US Environmental Protection Agency (R-82908901-0), the National Oceanographic and Atmospheric Administration (NAO 3NMF4720491) and the WHOI/MIT Joint Program in Oceanography