Social norm complexity and past reputations in the evolution of cooperation.

Indirect reciprocity is the most elaborate and cognitively demanding of all known cooperation mechanisms, and is the most specifically human because it involves reputation and status. By helping someone, individuals may increase their reputation, which may change the predisposition of others to help them in future. The revision of an individual's reputation depends on the social norms that establish what characterizes a good or bad action and thus provide a basis for morality. Norms based on indirect reciprocity are often sufficiently complex that an individual's ability to follow subjective rules becomes important, even in models that disregard the past reputations of individuals, and reduce reputations to either 'good' or 'bad' and actions to binary decisions. Here we include past reputations in such a model and identify the key pattern in the associated norms that promotes cooperation. Of the norms that comply with this pattern, the one that leads to maximal cooperation (greater than 90 per cent) with minimum complexity does not discriminate on the basis of past reputation; the relative performance of this norm is particularly evident when we consider a 'complexity cost' in the decision process. This combination of high cooperation and low complexity suggests that simple moral principles can elicit cooperation even in complex environments.

Robust Motor Imagery Tasks Classification Approach Using Bayesian Neural Network.

The development of Brain-Computer Interfaces based on Motor Imagery (MI) tasks is a relevant research topic worldwide. The design of accurate and reliable BCI systems remains a challenge, mainly in terms of increasing performance and usability. Classifiers based on Bayesian Neural Networks are proposed in this work by using the variational inference, aiming to analyze the uncertainty during the MI prediction. An adaptive threshold scheme is proposed here for MI classification with a reject option, and its performance on both datasets 2a and 2b from BCI Competition IV is compared with other approaches based on thresholds. The results using subject-specific and non-subject-specific training strategies are encouraging. From the uncertainty analysis, considerations for reducing computational cost are proposed for future work.

Real-World Performance of Susceptibility Testing for Ceftolozane/Tazobactam against Non-Carbapenemase-Producing Carbapenem-Resistant Pseudomonas aeruginosa.

Ceftolozane/tazbactam (C/T) is a potent anti-pseudomonal agent that has clinical utility against infections caused by non-carbapenemase, producing-carbapenem-resistant Pseudomonas aeruginosa (non-CP-CR-PA). Accurate, precise, and reliable antimicrobial susceptibility testing (AST) is crucial to guide clinical decisions. However, studies assessing the performance of different AST methods against non-CP-CR-PA (the main clinical niche for C/T), are lacking. Here, we evaluated performance of gradient strips (Etest and MIC test strip [MTS], and disk diffusion [DD]) using CLSI breakpoints. Additionally, we assessed the performance of DD using EUCAST breakpoints. For all susceptibility tests, we used a collection of 97 non-CP-CR-PA clinical isolates recovered from 11 Chilean hospitals. Both gradient strips and DD had acceptable performance when using CLSI breakpoints, yielding a categorical agreement (CA) of >90% and 92%, respectively. In contrast, DD using EUCAST breakpoints performed suboptimally (CA 81%). MTS yielded a higher essential agreement (EA, >90%) than Etest (84%). Importantly, the performance of all methods varied significantly when the isolates were stratified by their degree of susceptibility to other anti-pseudomonal ß-lactams. All methods had 100% CA when testing isolates that were pan-susceptible to all ß-lactams (Pan-ß-S). However, the CA markedly decreased when testing isolates resistant to all ß-lactams (Pan-ß-R). Indeed, the CA was 81% for Etest (six errors), 78% for MTS (seven errors), and 78% and 56% for DD when using CLSI (seven errors) or EUCAST breakpoints (14 errors), respectively. Our results suggest that all manual AST methods have strikingly decreased performance in the context of Pan-ß-R P. aeruginosa with potentially major clinical implications.

Cancer Care Access in Chile's Vulnerable Populations During the COVID-19 Pandemic.

Objectives. To examine the COVID-19 pandemic's impact on cancer care access in Chile, analyzing differential effects by insurance type, gender, and age. Methods. We conducted a quasi-experimental study using interrupted time series analysis. We used multiple data sources for a broad evaluation of cancer-related health care utilization from January 2017 to December 2020. We fit negative binomial models by population groups for a range of services and diagnoses. Results. A sharp drop in oncology health care utilization in March was followed by a slow, incomplete recovery over 2020. Cumulative cancer-related services, diagnostic confirmations, and sick leaves were reduced by one third in 2020; the decrease was more pronounced among women and the publicly insured. Early diagnosis was missed in 5132 persons with 4 common cancers. Conclusions. The pandemic stressed the Chilean health system, decreasing access to essential services, with a profound impact on cancer care. Oncology service reductions preceded large-scale lockdowns and supply-side disruptions. Importantly, not all population groups were equally affected, with patterns suggesting that gender and socioeconomic inequalities were exacerbated. (Am J Public Health. 2022;112(S6):S591-S601. https://doi.org/10.2105/AJPH.2021.306587).

[Cancer care access in Chile's vulnerable populations during the COVID-19 pandemicAcesso a tratamento de câncer em populações vulneráveis no Chile durante a pandemia de COVID-19]. / Acceso a la atención del cáncer en los grupos vulnerables de Chile durante la pandemia de COVID-19.

Objectives: To examine the COVID-19 pandemic's impact on cancer care access in Chile, analyzing differential effects by insurance type, gender, and age. Methods: We conducted a quasi-experimental study using interrupted time series analysis. We used multiple data sources for a broad evaluation of cancer-related health care utilization from January 2017 to December 2020. We fit negative binomial models by population groups for a range of services and diagnoses. Results: A sharp drop in oncology health care utilization in March was followed by a slow, incomplete recovery over 2020. Cumulative cancer-related services, diagnostic confirmations, and sick leaves were reduced by one third in 2020; the decrease was more pronounced among women and the publicly insured. Early diagnosis was missed in 5132 persons with 4 common cancers. Conclusions: The pandemic stressed the Chilean health system, decreasing access to essential services, with a profound impact on cancer care. Oncology service reductions preceded large-scale lockdowns and supply-side disruptions. Importantly, not all population groups were equally affected, with patterns suggesting that gender and socioeconomic inequalities were exacerbated.

Objetivos: Examinar o impacto da pandemia de COVID-19 no acesso a tratamento de câncer no Chile, analisando efeitos diferenciais por tipo de cobertura de assistência à saúde, gênero e idade. Métodos: Realizamos um estudo quase-experimental utilizando análise de séries temporais interrompidas. A partir de várias fontes de dados, efetuamos uma avaliação abrangente da utilização de atenção à saúde relacionada ao câncer, de janeiro de 2017 a dezembro de 2020. Ajustamos modelos binomiais negativos por grupos populacionais a vários tipos de serviços e diagnósticos. Resultados: Uma queda acentuada no uso da assistência médica oncológica em março foi seguida por uma recuperação lenta e incompleta ao longo de 2020. Cumulativamente, a utilização de serviços oncológicos, as confirmações de diagnóstico e os afastamentos do trabalho por doença foram reduzidos em um terço em 2020. Essa redução foi mais pronunciada em mulheres e usuários do sistema público de saúde. No total, 5132 pessoas com 4 cânceres comuns não foram diagnosticadas precocemente. Conclusões: A pandemia impôs pressão sobre o sistema de saúde chileno, reduzindo o acesso a serviços essenciais e causando um profundo impacto no tratamento do câncer. As reduções na prestação de serviços de oncologia precederam os lockdowns em larga escala e as interrupções na oferta de suprimentos. É importante ressaltar que nem todos os grupos populacionais foram igualmente afetados e os padrões observados sugerem que as desigualdades de gênero e socioeconômicas foram exacerbadas.

A Comparison of Deep Neural Networks for Monocular Depth Map Estimation in Natural Environments Flying at Low Altitude.

Currently, the use of Unmanned Aerial Vehicles (UAVs) in natural and complex environments has been increasing, because they are appropriate and affordable solutions to support different tasks such as rescue, forestry, and agriculture by collecting and analyzing high-resolution monocular images. Autonomous navigation at low altitudes is an important area of research, as it would allow monitoring parts of the crop that are occluded by their foliage or by other plants. This task is difficult due to the large number of obstacles that might be encountered in the drone's path. The generation of high-quality depth maps is an alternative for providing real-time obstacle detection and collision avoidance for autonomous UAVs. In this paper, we present a comparative analysis of four supervised learning deep neural networks and a combination of two for monocular depth map estimation considering images captured at low altitudes in simulated natural environments. Our results show that the Boosting Monocular network is the best performing in terms of depth map accuracy because of its capability to process the same image at different scales to avoid loss of fine details.

Gender disparities in access to care for time-sensitive conditions during COVID-19 pandemic in Chile.

BACKGROUND: During the COVID-19 pandemic, reductions in healthcare utilization are reported in different contexts. Nevertheless, studies have not explored specifically gender disparities in access to healthcare in the context of COVID-19. METHODS: To evaluate gender disparities in access to medical in Chile we conducted an interrupted time series analysis using segmented regression. The outcome variable was the number of weekly confirmed cases of a set of oncologic and cardiovascular time-sensitive conditions at a national level. The series contained data from weeks 1 to 39 for 2017 to 2020. The intervention period started at week 12. We selected this period because preventive interventions, such as school closures or teleworking, were implemented at this point. We estimated the level effect using a dummy variable indicating the intervention period and slope effect using a continuous variable from weeks 12 to 39. To test heterogeneity by gender and age group, we conducted a stratified analysis. RESULTS: We observed a sizable reduction in access to care with a slowly recovery for oncologic (level effect 0.323; 95% CI 0.291-0.359; slope effect 1.022; 95% CI 1.016-1.028) and cardiovascular diseases (level effect 0.586; 95% CI 0.564-0.609; slope effect 1.009; 95% CI 1.007-1.011). Greater reduction occurred in women compared to men, particularly marked on myocardial infarction (level effect 0.595; 95% CI 0.566-0.627 versus 0.532; 95% CI 0.502-0.564) and colorectal cancer (level effect 0.295; 95% CI 0.248-0.35 versus 0.19; 95% CI 0.159-0.228). Compared to men, a greater absolute reduction was observed in women for oncologic diseases, excluding sex-specific cancer, (1352; 95% CI 743-1961) and cardiovascular diseases (1268; 95% CI 946-1590). CONCLUSION: We confirmed a large drop in new diagnoses for time-sensitive conditions during the COVID-19 pandemic in Chile. This reduction was greater for women. Our findings should alert policy-makers about the urgent need to integrate a gender perspective into the pandemic response.

The impaired quorum sensing response of Pseudomonas aeruginosa MexAB-OprM efflux pump overexpressing mutants is not due to non-physiological efflux of 3-oxo-C12-HSL.

Multidrug (MDR) efflux pumps are ancient and conserved molecular machineries with relevant roles in different aspects of the bacterial physiology, besides antibiotic resistance. In the case of the environmental opportunistic pathogen Pseudomonas aeruginosa, it has been shown that overexpression of different efflux pumps is linked to the impairment of the quorum sensing (QS) response. Nevertheless, the causes of such impairment are different for each analysed efflux pump. Herein, we performed an in-depth analysis of the QS-mediated response of a P. aeruginosa antibiotic resistant mutant that overexpresses MexAB-OprM. Although previous work claimed that this efflux pump extrudes the QS signal 3-oxo-C12-HSL, we show otherwise. Our results evidence that the observed attenuation in the QS response when overexpressing this pump is related to an impaired production of alkyl quinolone QS signals, likely prompted by the reduced availability of one of their precursors, the octanoate. Together with previous studies, this indicates that, although the consequences of overexpressing efflux pumps are similar (impaired QS response), the underlying mechanisms are different. This 'apparent redundancy' of MDR efflux systems can be understood as a P. aeruginosa strategy to keep the robustness of the QS regulatory network and modulate its output in response to different signals.

Governance of risky public goods under graduated punishment.

Ensuring global cooperation often poses governance problems shadowed by the tragedy of the commons, as wrong-doers enjoy the benefits set up by right-doers at no cost. Institutional punishment of wrong-doers is well-known to curtail their impetus as free-riders. However, institutions often have limited scope in imposing sanctions, more so when these are strict and potentially viewed as disproportionate. Inspired by the design principles proposed by the late Nobel Prize Elinor Ostrom, here we study the evolution and impact of a new form of institutional sanctioning, where punishment is graduated, growing with the incidence of free-riding. We develop an analytical model capable of identifying the conditions under which this design principle is conducive to the self-organization of stable institutions and cooperation. We employ evolutionary game theory in finite populations and non-linear public goods dilemmas in the presence of risk of global losses whose solution requires the self-organization of decision makers into an overall cooperative state. We show that graduated punishment is more effective in promoting widespread cooperation than conventional forms of punishment studied to date, being also less severe and thus, presumably, easier to implement. This effect is enhanced whenever the costs of its implementation are positively correlated with the severity of punishment. We frame our model within the context of the global reduction of carbon emissions, but the results are shown to be general enough to be applicable to other collective action problems, shedding further light into the origins of Human institutions.

Pseudomonas fildesensis sp. nov., a psychrotolerant bacterium isolated from Antarctic soil of King George Island, South Shetland Islands.

The strain KG01T was isolated from a soil sample from King George Island, Antarctica. Cells of KG01T are rod-shaped and motile by means of multiple polar flagella. The absence of arginine dihydrolase activity could be a key feature to readily distinguish KG01T from its closest phylogenetic relative species. The main fatty acids of the strain include summed feature 3 (C16 : 1 ω7c and/or C15 : 0 iso 2-OH), C16 : 0 and C18 : 1 ω7c. Phylogenetic analysis based on the 16S rRNA gene sequence and on a multilocus sequence analysis (MLSA) using housekeeping genes (16S rRNA, rpoB, rpoD, gyrB) were carried out. These analyses allowed us to include the strain within the Pseudomonas fluorescens group, presenting the highest similarity of multilocus sequence with Pseudomonas veronii LMG 17761T (96.67 %). The genome of KG01T was sequenced and in silico compared with genomes of the most closely related species of the P. fluorescens group. The average nucleotide identity (ANIb) and average amino acid identity (AAI) values of the species phylogenetically closest to KG01T were less than 95-96 %, threshold currently accepted to define strain as belonging to a bacterial species, the highest scores being those to Pseudomonas veronii LMG 17761T (87.98 %) and Pseudomonas marginalis ICMP 3553T (91.90 %). Therefore, the phenotypic and genotypic analyses results, allow us to propose that KG01T represents a member of a novel species of the genus Pseudomonas, for which the name Pseudomonas fildesensis is proposed, and KG01T (=CECT 9084T;=DSM 102036T) is established as the type strain .

Analysis of the Pseudomonas aeruginosa Aminoglycoside Differential Resistomes Allows Defining Genes Simultaneously Involved in Intrinsic Antibiotic Resistance and Virulence.

High-throughput screening of transposon insertion libraries is a useful strategy for unveiling bacterial genes whose inactivation results in an altered susceptibility to antibiotics. A potential drawback of these studies is they are usually based on just one model antibiotic for each structural family, under the assumption that the results can be extrapolated to all members of said family. To determine if this simplification is appropriate, we have analyzed the susceptibility of mutants of Pseudomonas aeruginosa to four aminoglycosides. Our results indicate that each mutation produces different effects on susceptibility to the tested aminoglycosides, with only two mutants showing similar changes in the susceptibility to all studied aminoglycosides. This indicates that the role of a particular gene in the resistome of a given antibiotic should not be generalized to other members of the same structural family. Five aminoglycoside-hypersusceptible mutants inactivating glnD, hflK, PA2798, PA3016, and hpf were chosen for further analysis in order to elucidate if lower aminoglycoside susceptibility correlates with cross-hypersusceptibility to other antibiotics and with impaired virulence. Our results indicate that glnD inactivation leads to increased cross-susceptibility to different antibiotics. The mutant in this gene is strongly impaired in virulence traits such as pyocyanin production, biofilm formation, elastase activity, and swarming motility and the ability to kill Caenorhabditis elegans Thus, GlnD might be an interesting target for developing antibiotic coadjuvants with antiresistance and antivirulence properties against P. aeruginosa.

Evolutionary dynamics of paroxysmal nocturnal hemoglobinuria.

Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal blood disorder characterized by hemolysis and a high risk of thrombosis, that is due to a deficiency in several cell surface proteins that prevent complement activation. Its origin has been traced to a somatic mutation in the PIG-A gene within hematopoietic stem cells (HSC). However, to date the question of how this mutant clone expands in size to contribute significantly to hematopoiesis remains under debate. One hypothesis posits the existence of a selective advantage of PIG-A mutated cells due to an immune mediated attack on normal HSC, but the evidence supporting this hypothesis is inconclusive. An alternative (and simpler) explanation attributes clonal expansion to neutral drift, in which case selection neither favours nor inhibits expansion of PIG-A mutated HSC. Here we examine the implications of the neutral drift model by numerically evolving a Markov chain for the probabilities of all possible outcomes, and investigate the possible occurrence and evolution, within this framework, of multiple independently arising clones within the HSC pool. Predictions of the model agree well with the known incidence of the disease and average age at diagnosis. Notwithstanding the slight difference in clonal expansion rates between our results and those reported in the literature, our model results lead to a relative stability of clone size when averaging multiple cases, in accord with what has been observed in human trials. The probability of a patient harbouring a second clone in the HSC pool was found to be extremely low ([Formula: see text]). Thus our results suggest that in clinical cases of PNH where two independent clones of mutant cells are observed, only one of those is likely to have originated in the HSC pool.

Stochastic Dynamics through Hierarchically Embedded Markov Chains.

Studying dynamical phenomena in finite populations often involves Markov processes of significant mathematical and/or computational complexity, which rapidly becomes prohibitive with increasing population size or an increasing number of individual configuration states. Here, we develop a framework that allows us to define a hierarchy of approximations to the stationary distribution of general systems that can be described as discrete Markov processes with time invariant transition probabilities and (possibly) a large number of states. This results in an efficient method for studying social and biological communities in the presence of stochastic effects-such as mutations in evolutionary dynamics and a random exploration of choices in social systems-including situations where the dynamics encompasses the existence of stable polymorphic configurations, thus overcoming the limitations of existing methods. The present formalism is shown to be general in scope, widely applicable, and of relevance to a variety of interdisciplinary problems.

Social Norms of Cooperation in Small-Scale Societies.

Indirect reciprocity, besides providing a convenient framework to address the evolution of moral systems, offers a simple and plausible explanation for the prevalence of cooperation among unrelated individuals. By helping someone, an individual may increase her/his reputation, which may change the pre-disposition of others to help her/him in the future. This, however, depends on what is reckoned as a good or a bad action, i.e., on the adopted social norm responsible for raising or damaging a reputation. In particular, it remains an open question which social norms are able to foster cooperation in small-scale societies, while enduring the wide plethora of stochastic affects inherent to finite populations. Here we address this problem by studying the stochastic dynamics of cooperation under distinct social norms, showing that the leading norms capable of promoting cooperation depend on the community size. However, only a single norm systematically leads to the highest cooperative standards in small communities. That simple norm dictates that only whoever cooperates with good individuals, and defects against bad ones, deserves a good reputation, a pattern that proves robust to errors, mutations and variations in the intensity of selection.

Sulforaphane prevents quinolinic acid-induced mitochondrial dysfunction in rat striatum.

Quinolinic acid (QA) triggers striatal neuronal death by an excitotoxic cascade that involves oxidative stress, which in turns is tightly linked to mitochondria. Mitochondrial dysfunction is a molecular feature described in several brain pathologies. In this work, we determined whether the sulforaphane-neuroprotective effect in the rodent experimental model of Huntington's disease induced by QA is associated with mitochondrial function preservation. We found that QA impaired mitochondrial function within 24 h post-lesion. Sulforaphane effectively disrupted the mitochondrial dysfunction by preventing the decrease in respiratory control ratio, transmembrane potential, ability to synthetize ATP, and the activity of mitochondrial complexes I, II, and IV.

Climate policies under wealth inequality.

Taming the planet's climate requires cooperation. Previous failures to reach consensus in climate summits have been attributed, among other factors, to conflicting policies between rich and poor countries, which disagree on the implementation of mitigation measures. Here we implement wealth inequality in a threshold public goods dilemma of cooperation in which players also face the risk of potential future losses. We consider a population exhibiting an asymmetric distribution of rich and poor players that reflects the present-day status of nations and study the behavioral interplay between rich and poor in time, regarding their willingness to cooperate. Individuals are also allowed to exhibit a variable degree of homophily, which acts to limit those that constitute one's sphere of influence. Under the premises of our model, and in the absence of homophily, comparison between scenarios with wealth inequality and without wealth inequality shows that the former leads to more global cooperation than the latter. Furthermore, we find that the rich generally contribute more than the poor and will often compensate for the lower contribution of the latter. Contributions from the poor, which are crucial to overcome the climate change dilemma, are shown to be very sensitive to homophily, which, if prevalent, can lead to a collapse of their overall contribution. In such cases, however, we also find that obstinate cooperative behavior by a few poor may largely compensate for homophilic behavior.

Linking Individual and Collective Behavior in Adaptive Social Networks.

Adaptive social structures are known to promote the evolution of cooperation. However, up to now the characterization of the collective, population-wide dynamics resulting from the self-organization of individual strategies on a coevolving, adaptive network has remained unfeasible. Here we establish a (reversible) link between individual (micro)behavior and collective (macro)behavior for coevolutionary processes. We demonstrate that an adaptive network transforms a two-person social dilemma locally faced by individuals into a collective dynamics that resembles that associated with an N-person coordination game, whose characterization depends sensitively on the relative time scales between the entangled behavioral and network evolutions. In particular, we show that the faster the relative rate of adaptation of the network, the smaller the critical fraction of cooperators required for cooperation to prevail, thus establishing a direct link between network adaptation and the evolution of cooperation. The framework developed here is general and may be readily applied to other dynamical processes occurring on adaptive networks, notably, the spreading of contagious diseases or the diffusion of innovations.

Co-evolutionary dynamics of collective action with signaling for a quorum.

Collective signaling for a quorum is found in a wide range of organisms that face collective action problems whose successful solution requires the participation of some quorum of the individuals present. These range from humans, to social insects, to bacteria. The mechanisms involved, the quorum required, and the size of the group may vary. Here we address the general question of the evolution of collective signaling at a high level of abstraction. We investigate the evolutionary dynamics of a population engaging in a signaling N-person game theoretic model. Parameter settings allow for loners and cheaters, and for costly or costless signals. We find a rich dynamics, showing how natural selection, operating on a population of individuals endowed with the simplest strategies, is able to evolve a costly signaling system that allows individuals to respond appropriately to different states of Nature. Signaling robustly promotes cooperative collective action, in particular when coordinated action is most needed and difficult to achieve. Two different signaling systems may emerge depending on Nature's most prevalent states.

Evolutionary dynamics of collective index insurance.

Index-based insurances offer promising opportunities for climate-risk investments in developing countries. Indeed, contracts conditional on, e.g., weather or livestock indexes can be cheaper to set up than conventional indemnity-based insurances, while offering a safety net to vulnerable households, allowing them to eventually escape poverty traps. Moreover, transaction costs by insurance companies may be additionally reduced if contracts, instead of arranged with single households, are endorsed by collectives of households that bear the responsibility of managing the division of the insurance coverage by its members whenever the index is surpassed, allowing for additional flexibility in what concerns risk-sharing and also allowing insurance companies to avoid the costs associated with moral hazard. Here we resort to a population dynamics framework to investigate under which conditions household collectives may find collective index insurances attractive, when compared with individual index insurances. We assume risk sharing among the participants of each collective, and model collective action in terms of an N-person threshold game. Compared to less affordable individual index insurances, we show how collective index insurances lead to a coordination problem in which the adoption of index insurances may become the optimal decision, spreading index insurance coverage to the entire population. We further investigate the role of risk-averse and risk-prone behaviors, as well as the role of partial correlation between insurance coverage and actual loss of crops, and in which way these affect the original coordination thresholds.

Evolutionary dynamics of group fairness.

The emergence and impact of fairness is commonly studied in the context of 2-person games, notably the Ultimatum Game. Often, however, humans face problems of collective action involving more than two individuals where fairness is known to play a very important role, and whose dynamics cannot be inferred from what is known from 2-person games. Here, we propose a generalization of the Ultimatum Game for an arbitrary number of players--the Multiplayer Ultimatum Game. Proposals are made to a group of responders who must individually reject or accept the proposal. If the total number of individual acceptances stands below a given threshold, the offer will be rejected; otherwise, the offer will be accepted, and equally shared by all responders. We investigate the evolution of fairness in populations of individuals by means of evolutionary game theory, providing both analytical insights and results from numerical simulations. We show how imposing stringent consensuses significantly increases the value of the proposals, leading to fairer outcomes and more tolerant players. Furthermore, we show how stochastic effects--such as imitation errors and/or errors when assessing the fitness of others--may further enhance the overall success in reaching fair collective action.