1. Endogenous social distancing and its underappreciated impact on the epidemic curveMarko Gosak, Moritz U. G. Kraemer, Heinrich H. Nax, Matjaž Perc, Bary S. R. Pradelski, 2021, original scientific article Abstract: Social distancing is an efective strategy to mitigate the impact of infectious diseases. If sick or healthy, or both, predominantly socially distance, the epidemic curve fattens. Contact reductions may occur for diferent reasons during a pandemic including health-related mobility loss (severity of symptoms), duty of care for a member of a high-risk group, and forced quarantine. Other decisions to reduce contacts are of a more voluntary nature. In particular, sick people reduce contacts consciously to avoid infecting others, and healthy individuals reduce contacts in order to stay healthy. We use game theory to formalize the interaction of voluntary social distancing in a partially infected population. This improves the behavioral micro-foundations of epidemiological models, and predicts diferential social distancing rates dependent on health status. The model's key predictions in terms of comparative statics are derived, which concern changes and interactions between social distancing behaviors of sick and healthy. We ft the relevant parameters for endogenous social distancing to an epidemiological model with evidence from infuenza waves to provide a benchmark for an epidemic curve with endogenous social distancing. Our results suggest that spreading similar in peak and case numbers to what partial immobilization of the population produces, yet quicker to pass, could occur endogenously. Going forward, eventual social distancing orders and lockdown policies should be benchmarked against more realistic epidemic models that take endogenous social distancing into account, rather than be driven by static, and therefore unrealistic, estimates for social mixing that intrinsically overestimate spreading.
Keywords: COVID-19, pandemic, disease dynamics, exponential growth, virality
Published in DKUM: 14.08.2024; Views: 118; Downloads: 3
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2. What is it worth? : Determining the capital stock of european hydropower plantsPetra Gsodam, Heinrich Stigler, published scientific conference contribution Abstract: High lifetimes and high capital intensities characterize fixed assets of electric utilities. The historical cost concept implicate that long-lasting fixed assets are shown too low in balance sheets of electric utilities: the real value of long-lasting assets is not shown because of nominal price increases. An alternative to show the real value of longterm assets represents the capital stock concept based on replacement values less depreciations (net capital stock). To calculate the capital stock, information regarding the level of investment in each power plant at the time of construction (historical acquisition values) and with regard to a common base year (replacement values) is necessary. This paper shows how the not-standardized investments in hydropower plants can be estimated and how the capital stock of run-of-river and threshold hydropower plants can be calculated. Long-term assets in the form of run-of-river and threshold hydropower plants are compared based on historic costs and replacement values. The paper concludes that given nominal price increases for replacement investments, as is the case with long-lasting hydropower plants, only depreciations based on replacement values can ensure preservation of the company’s assets.
Keywords: fixed assets, electric utilities, balance sheet, capital stock, depreciation
Published in DKUM: 11.10.2017; Views: 1343; Downloads: 212
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3. Stability of cooperation under image scoring in group interactionsHeinrich H. Nax, Matjaž Perc, Attila Szolnoki, Dirk Helbing, 2015, original scientific article Abstract: Image scoring sustains cooperation in the repeated two-player prisoner's dilemma through indirect reciprocity, even though defection is the uniquely dominant selfish behaviour in the one-shot game. Many real-world dilemma situations, however, firstly, take place in groups and, secondly, lack the necessary transparency to inform subjects reliably of others' individual past actions. Instead, there is revelation of information regarding groups, which allows for "group scoring" but not for image scoring. Here, we study how sensitive the positive results related to image scoring are to information based on group scoring. We combine analytic results and computer simulations to specify the conditions for the emergence of cooperation. We show that under pure group scoring, that is, under the complete absence of image-scoring information, cooperation is unsustainable. Away from this extreme case, however, the necessary degree of image scoring relative to group scoring depends on the population size and is generally very small. We thus conclude that the positive results based on image scoring apply to a much broader range of informational settings that are relevant in the real world than previously assumed.
Keywords: public goods, group interactions, phase transition, social dilemma, physics of social systems
Published in DKUM: 23.06.2017; Views: 1516; Downloads: 455
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4. Directional learning and the provisioning of public goodsHeinrich H. Nax, Matjaž Perc, 2015, original scientific article Abstract: We consider an environment where players are involved in a public goods game and must decide repeatedly whether to make an individual contribution or not. However, players lack strategically relevant information about the game and about the other players in the population. The resulting behavior of players is completely uncoupled from such information, and the individual strategy adjustment dynamics are driven only by reinforcement feedbacks from each player's own past. We show that the resulting "directional learning" is sufficient to explain cooperative deviations away from the Nash equilibrium. We introduce the concept of k-strong equilibria, which nest both the Nash equilibrium and the Aumann-strong equilibrium as two special cases, and we show that, together with the parameters of the learning model, the maximal k-strength of equilibrium determines the stationary distribution. The provisioning of public goods can be secured even under adverse conditions, as long as players are sufficiently responsive to the changes in their own payoffs and adjust their actions accordingly. Substantial levels of public cooperation can thus be explained without arguments involving selflessness or social preferences, solely on the basis of uncoordinated directional (mis)learning.
Keywords: cooperation, public goods, directional learning, phase transitions, physics of social systems
Published in DKUM: 23.06.2017; Views: 1097; Downloads: 353
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