Apology and forgiveness evolve to resolve failures in cooperative agreements

Making agreements on how to behave has been shown to be an evolutionarily viable strategy in one-shot social dilemmas. However, in many situations agreements aim to establish long-term mutually beneficial interactions. Our analytical and numerical results reveal for the first time under which conditions revenge, apology and forgiveness can evolve and deal with mistakes within ongoing agreements in the context of the Iterated Prisoners Dilemma. We show that, when the agreement fails, participants prefer to take revenge by defecting in the subsisting encounters. Incorporating costly apology and forgiveness reveals that, even when mistakes are frequent, there exists a sincerity threshold for which mistakes will not lead to the destruction of the agreement, inducing even higher levels of cooperation. In short, even when to err is human, revenge, apology and forgiveness are evolutionarily viable strategies which play an important role in inducing cooperation in repeated dilemmas.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Generosity Pays in the Presence of Direct Reciprocity: A Comprehensive Study of 2×2 Repeated Games

By applying a technique previously developed to study ecosystem assembly [Capitán et al., Phys. Rev. Lett. 103, 168101 (2009)] we study the evolutionary stable strategies of iterated 22 games. We focus on memory-one strategies, whose probability to play a given action depends on the actions of both players in the previous time step. We find the asymptotically stable populations resulting from all possible invasions of any known stable population. The results of this invasion process are interpreted as transitions between different populations that occur with a certain probability. Thus the whole process can be described as a Markov chain whose states are the different stable populations. With this approach we are able to study the whole space of symmetric 22 games, characterizing the most probable results of evolution for the different classes of games. Our analysis includes quasi-stationary mixed equilibria that are relevant as very long-lived metastable states and is compared to the predictions of a fixation probability analysis. We confirm earlier results on the success of the Pavlov strategy in a wide range of parameters for the iterated Prisoner's Dilemma, but find that as the temptation to defect grows there are many other possible successful strategies. Other regions of the diagram reflect the equilibria structure of the underlying one-shot game, albeit often some non-expected strategies arise as well. We thus provide a thorough analysis of iterated 22 games from which we are able to extract some general conclusions. Our most relevant finding is that a great deal of the payoff parameter range can still be understood by focusing on win-stay, lose-shift strategies, and that very ambitious ones, aspiring to obtaining always a high payoff, are never evolutionary stable

When agreement-accepting free-riders are a necessary evil for the evolution of cooperation

Agreements and commitments have provided a novel mechanism to promote cooperation in social dilemmas in both one-shot and repeated games. Individuals requesting others to commit to cooperate (proposers) incur a cost, while their co-players are not necessarily required to pay any, allowing them to free-ride on the proposal investment cost (acceptors). Although there is a clear complementarity in these behaviours, no dynamic evidence is currently available that proves that they coexist in different forms of commitment creation. Using a stochastic evolutionary model allowing for mixed population states, we identify non-trivial roles of acceptors as well as the importance of intention recognition in commitments. In the one-shot prisoner's dilemma, alliances between proposers and acceptors are necessary to isolate defectors when proposers do not know the acceptance intentions of the others. However, when the intentions are clear beforehand, the proposers can emerge by themselves. In repeated games with noise, the incapacity of proposers and acceptors to set up alliances makes the emergence of the first harder whenever the latter are present. As a result, acceptors will exploit proposers and take over the population when an apology-forgiveness mechanism with too low apology cost is introduced, and hence reduce the overall cooperation level.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Long daytime napping is associated with increased adiposity and type 2 diabetes in an elderly population with metabolic syndrome

Research examining associations between objectively-measured napping time and type 2 diabetes (T2D) is lacking. This study aimed to evaluate daytime napping in relation to T2D and adiposity measures in elderly individuals from the Mediterranean region. A cross-sectional analysis of baseline data from 2190 elderly participants with overweight/obesity and metabolic syndrome, in the PREDIMED-Plus trial, was carried out. Accelerometer-derived napping was measured. Prevalence ratios (PR) and 95% confidence intervals (CI) for T2D were obtained using multivariable-adjusted Cox regression with constant time. Linear regression models were fitted to examine associations of napping with body mass index (BMI) and waist circumference (WC). Participants napping ≥90 min had a higher prevalence of T2D (PR 1.37 (1.06, 1.78)) compared with those napping 5 to <30 min per day. Significant positive associations with BMI and WC were found in those participants napping ≥30 min as compared to those napping 5 to <30 min per day. The findings of this study suggest that longer daytime napping is associated with higher T2D prevalence and greater adiposity measures in an elderly Spanish population at high cardiovascular risk

A Combination of Preliminary Electroweak Measurements and Constraints on the Standard Model, 2002

his note presents a combination of published and preliminary electroweak results from the four LEP collaborations and the SLD collaboration which were prepared for the 2002 summer conferences. Averages from Z resonance results are derived for hadronic and leptonic cross sections, the leptonic forward-backward asymmetries, the tau polarisation asymmetries, the b-bbar and c-cbar partial widths and forward-backward asymmetries and the q-qbar charge asymmetry. Above the Z resonance, averages are derived for di-fermion cross sections and forward-backward asymmetries, photon-pair, W-pair, Z-pair single-W and single-Z cross sections, electroweak gauge boson couplings, W mass and width and W decay branching ratios. The main changes with respect to the experimental results presented in summer 2001 are updates to the Z-pole heavy flavour results from SLD and LEP, and new combinations of results above the Z pole. A new investigation of the interference of photon and Z-boson exchange is presented. For the first time, colour reconnection and Bose-Einstein correlation analyses in W-pair production are combined. The results are compared with precise electroweak measurements from other experiments, notably the recent final result on the electroweak mixing angle determined in neutrino-nucleon scattering by the NuTeV collaboration. The parameters of the Standard Model are evaluated, first using the combined LEP electroweak measurements, and then using the full set of electroweak results

Predictive Power of the "Trigger Tool" for the detection of adverse events in general surgery: a multicenter observational validation study

Background In spite of the global implementation of standardized surgical safety checklists and evidence-based practices, general surgery remains associated with a high residual risk of preventable perioperative complications and adverse events. This study was designed to validate the hypothesis that a new “Trigger Tool” represents a sensitive predictor of adverse events in general surgery. Methods An observational multicenter validation study was performed among 31 hospitals in Spain. The previously described “Trigger Tool” based on 40 specific triggers was applied to validate the predictive power of predicting adverse events in the perioperative care of surgical patients. A prediction model was used by means of a binary logistic regression analysis. Results The prevalence of adverse events among a total of 1,132 surgical cases included in this study was 31.53%. The “Trigger Tool” had a sensitivity and specificity of 86.27% and 79.55% respectively for predicting these adverse events. A total of 12 selected triggers of overall 40 triggers were identified for optimizing the predictive power of the “Trigger Tool”. Conclusions The “Trigger Tool” has a high predictive capacity for predicting adverse events in surgical procedures. We recommend a revision of the original 40 triggers to 12 selected triggers to optimize the predictive power of this tool, which will have to be validated in future studies

Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine

[This corrects the article DOI: 10.1186/s13054-016-1208-6.]

Nurses' perceptions of aids and obstacles to the provision of optimal end of life care in ICU

Contains fulltext : 172380.pdf (publisher's version ) (Open Access

Effect of sustained load on the flexural bearing capacity of polypropylene fibre and minimum steel-bar reinforced concrete beams

Macro-synthetic fibres are becoming increasingly attractive as concrete reinforcement in structural applications, polypropylene fibre reinforced concrete, and macro-synthetic fibre reinforced concrete (MSFRC) in general, being an example of this tendency. Nonetheless, further knowledge needs to be gathered in relation with the time-dependant properties (i.e., creep) of the MSFRCs when its use is oriented to design-for-cracking structural elements. For this purpose, an extensive experimental programme was carried out on the flexural load bearing capacity of full-scale MSFRC beams (with mini-mum conventional steel reinforcement). Namely, beams with spans of 3 m and cross-section size of 200×250 mm were produced from a C40/50 concrete with 0 (reference), 3 and 9 kg/m3 of polypropylene fibres. Four beams were cast from each concrete type. After 28 days, two beams from each concrete type were tested until failure in three-point bending configuration. Then, one beam from each concrete was placed under sustained load for one year in a four-point bending configuration, whereas another beam from each concrete was left unloaded for one year under the same environmental conditions. After one year, both remaining beams from each concrete were tested until failure in bending. The results of the tests allowed assessing the effects of the sustained load on the remaining bearing capacity of the beams and confirming that the inclusion of a minimum steel-bar reinforcement was sufficient to prevent the beams from uncontrolled deformations triggered by tertiary tensile creep. The results were accompanied by full physical-mechanical characterization of the concretes. The preliminary results presented herein allow confirming that using MSFRC in cracking-allowed structural applications -with at least minimum mechanical (as per codes) steel-bar reinforcement amount- is reliable from the structural standpoint.The authors want also express their gratitude to the Spanish Ministry of Science and Innovation for the financial support received under the scope of the project CREEF (Creep and Fatigue of fibre reinforced concrete elements) (PID2019-108978RB-C32). This study has also received funding from Master Build-ers Solutions. This support is gratefully acknowledged. Any opinions, findings, conclusions, and/or rec-ommendations in the paper are those of the authors and do not necessarily represent the views of the individuals or organizations acknowledged.Postprint (published version