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Journal of the Royal Society, Interface Jan 2021We study the evolutionary dynamics of the Prisoner's Dilemma game in which cooperators and defectors interact with another actor type called exiters. Rather than being...
We study the evolutionary dynamics of the Prisoner's Dilemma game in which cooperators and defectors interact with another actor type called exiters. Rather than being exploited by defectors, exiters exit the game in favour of a small pay-off. We find that this simple extension of the game allows cooperation to flourish in well-mixed populations when iterations or reputation are added. In networked populations, however, the exit option is less conducive to cooperation. Instead, it enables the coexistence of cooperators, defectors, and exiters through cyclic dominance. Other outcomes are also possible as the exit pay-off increases or the network structure changes, including network-wide oscillations in actor abundances that may cause the extinction of exiters and the domination of defectors, although game parameters should favour exiting. The complex dynamics that emerges in the wake of a simple option to exit the game implies that nuances matter even if our analyses are restricted to incentives for rational behaviour.
Topics: Biological Evolution; Cooperative Behavior; Game Theory
PubMed: 33435841
DOI: 10.1098/rsif.2020.0777 -
Scientific Reports Mar 2022When our eyes are confronted with discrepant images (yielding incompatible retinal inputs) interocular competition (IOC) is instigated. During IOC, one image temporarily...
When our eyes are confronted with discrepant images (yielding incompatible retinal inputs) interocular competition (IOC) is instigated. During IOC, one image temporarily dominates perception, while the other is suppressed. Many factors affecting IOC have been extensively examined. One factor that received surprisingly little attention, however, is the stimulus' visual hemifield (VHF) of origin. This is remarkable, as the VHF location of stimuli is known to affect visual performance in various contexts. Prompted by exploratory analyses, we examined five independent datasets of breaking continuous flash suppression experiments, to establish the VHF's role in IOC. We found that targets presented in nasal VHF locations broke through suppression much faster than targets in temporal VHF locations. Furthermore, we found that the magnitude of this nasal advantage depended on how strongly the targets were suppressed: the nasal advantage was larger for the recessive eye than for the dominant eye, and was larger in observers with a greater dominance imbalance between the eyes. Our findings suggest that the nasal advantage reported here originates in processing stages where IOC is resolved. Finally, we propose that a nasal advantage in IOC serves an adaptive role in human vision, as it can aid perception of partially occluded objects.
Topics: Attention; Humans; Photic Stimulation; Retina; Vision, Binocular; Visual Fields; Visual Perception
PubMed: 35301373
DOI: 10.1038/s41598-022-08473-w -
Mathematical Biosciences and... Mar 2021Active fluids consume fuel at the microscopic scale, converting this energy into forces that can drive macroscopic motions over scales far larger than their microscopic...
Active fluids consume fuel at the microscopic scale, converting this energy into forces that can drive macroscopic motions over scales far larger than their microscopic constituents. In some cases, the mechanisms that give rise to this phenomenon have been well characterized, and can explain experimentally observed behaviors in both bulk fluids and those confined in simple stationary geometries. More recently, active fluids have been encapsulated in viscous drops or elastic shells so as to interact with an outer environment or a deformable boundary. Such systems are not as well understood. In this work, we examine the behavior of droplets of an active nematic fluid. We study their linear stability about the isotropic equilibrium over a wide range of parameters, identifying regions in which different modes of instability dominate. Simulations of their full dynamics are used to identify their nonlinear behavior within each region. When a single mode dominates, the droplets behave simply: as rotors, swimmers, or extensors. When parameters are tuned so that multiple modes have nearly the same growth rate, a pantheon of modes appears, including zigzaggers, washing machines, wanderers, and pulsators.
PubMed: 33892575
DOI: 10.3934/mbe.2021145 -
Applied and Environmental Microbiology Sep 2021In the environment, nutrients are rarely available in a constant supply. Therefore, microorganisms require strategies to compete for limiting nutrients. In freshwater...
In the environment, nutrients are rarely available in a constant supply. Therefore, microorganisms require strategies to compete for limiting nutrients. In freshwater systems, ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB) compete with heterotrophic bacteria, photosynthetic microorganisms, and each other for ammonium, which AOA and AOB utilize as their sole source of energy and nitrogen. We investigated the competition between highly enriched cultures of AOA (AOA-AC1) and AOB (AOB-G5-7) for ammonium. Based on the gene, the newly enriched archaeal ammonia oxidizer in AOA-AC1 was closely related to spp., and the bacterial ammonia oxidizer in AOB-G5-7, sp. strain Is79, belonged to the Nitrosomonas oligotropha group ( cluster 6a). Growth experiments in batch cultures showed that AOB-G5-7 had higher growth rates than AOA-AC1 at higher ammonium concentrations. During chemostat competition experiments under ammonium-limiting conditions, AOA-AC1 dominated the cultures, while AOB-G5-7 decreased in abundance. In batch cultures, the outcome of the competition between AOA and AOB was determined by the initial ammonium concentrations. AOA-AC1 was the dominant ammonia oxidizer at an initial ammonium concentration of 50 μM, and AOB-G5-7 was dominant at 500 μM. These findings indicate that during direct competition, AOA-AC1 was able to use ammonium that was unavailable to AOB-G5-7, while AOB-G5-7 dominated at higher ammonium concentrations. The results are in strong accordance with environmental survey data suggesting that AOA are mainly responsible for ammonia oxidation under more oligotrophic conditions, whereas AOB dominate under eutrophic conditions. Nitrification is an important process in the global nitrogen cycle. The first step, ammonia oxidation to nitrite, can be carried out by ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB). In many natural environments, these ammonia oxidizers coexist. Therefore, it is important to understand the population dynamics in response to increasing ammonium concentrations. Here, we study the competition between AOA and AOB enriched from freshwater systems. The results demonstrate that AOA are more abundant in systems with low ammonium availabilities and that AOB are more abundant when the ammonium availability increases. These results will help to predict potential shifts in the community composition of ammonia oxidizers in the environment due to changes in ammonium availability.
Topics: Ammonia; Archaea; Fresh Water; Microbial Interactions; Nitrosomonas; Oxidation-Reduction; Phylogeny
PubMed: 34347515
DOI: 10.1128/AEM.01038-21 -
The ISME Journal Nov 2022The mammalian intestine harbors heterogeneous distribution of microbes among which specific taxa (e.g. Lactobacillus) dominate across mammals. Deterministic factors such...
The mammalian intestine harbors heterogeneous distribution of microbes among which specific taxa (e.g. Lactobacillus) dominate across mammals. Deterministic factors such as nutrient availability and utilization may affect microbial distributions. Due to physiological complexity, mechanisms linking nutrient utilization and the dominance of key taxa remain unclear. Lactobacillus amylovorus is a predominant species in the small intestine of pigs. Employing a pig model, we found that the small intestine was dominated by Lactobacillus and particularly L. amylovorus, and enriched with peptide-bound amino acids (PBAAs), all of which were further boosted after a peptide-rich diet. To investigate the bacterial growth dominance mechanism, a representative strain L. amylovorus S1 was isolated from the small intestine and anaerobically cultured in media with free amino acids or peptides as sole nitrogen sources. L. amylovorus S1 grew preferentially with peptide-rich rather than amino acid-rich substrates, as reflected by enhanced growth and PBAA utilization, and peptide transporter upregulations. Utilization of free amino acids (e.g. methionine, valine, lysine) and expressions of transporters and metabolic enzymes were enhanced simultaneously in peptide-rich substrate. Additionally, lactate was elevated in peptide-rich substrates while acetate in amino acid-rich substrates, indicating distinct metabolic patterns depending on substrate forms. These results suggest that an increased capability of utilizing PBAAs contributes to the dominance of L. amylovorus, indicating amino acid utilization as a deterministic factor affecting intestinal microbial distribution. These findings may provide new insights into the microbe-gut nutrition interplay and guidelines for dietary manipulations toward gut health especially small intestine health.
Topics: Amino Acids; Animals; Lactates; Lactobacillus; Lactobacillus acidophilus; Lysine; Mammals; Methionine; Nitrogen; Swine; Valine
PubMed: 35896730
DOI: 10.1038/s41396-022-01287-8 -
ISME Communications Aug 2022Multiple carbapenem-resistant Klebsiella pneumoniae (CRKP) clones typically co-exist in hospital wards, but often certain clones will dominate. The factors driving this...
Multiple carbapenem-resistant Klebsiella pneumoniae (CRKP) clones typically co-exist in hospital wards, but often certain clones will dominate. The factors driving this dominance are largely unclear. This study began from a genomic epidemiology analysis and followed by multiple approaches to identify the potential mechanisms driving the successful spread of a dominant clone. 638 patients in a 50-bed ICU were screened. 171 (26.8%) and 21 had CRKP from swabs and clinical specimens, respectively. Many (39.8% of those with ≥7-day ICU stay) acquired CRKP. After removing 18 unable to recover, 174 CRKP isolates were genome sequenced and belonged to six sequence types, with ST11 being the most prevalent (n = 154, 88.5%) and most (n = 169, 97.1%) carrying bla. The 154 ST11 isolates belonged to 7 clones, with one (clone 1, KL64 capsular type) being dominant (n = 130, 84.4%). Clone 1 and the second-most common clone (clone 2, KL64, n = 15, 9.7%) emerged simultaneously, which was also detected by genome-based dating. Clone 1 exhibited decreased biofilm formation, shorter environment survival, and attenuated virulence. In murine gut, clone 1 outcompeted clone 2. Transcriptomic analysis showed significant upregulation of the ethanolamine operon in clone 1 when competing with clone 2. Clone 1 exhibited increased utilization of ethanolamine as a nitrogen source. This highlights that reduced virulence and enhanced ability to utilize ethanolamine may promote the success of nosocomial multidrug-resistant clones.
PubMed: 37938732
DOI: 10.1038/s43705-022-00163-y -
Beyoglu Eye Journal 2023The purpose was to study the association between ocular dominance, refractive status, and biometric parameters.
OBJECTIVES
The purpose was to study the association between ocular dominance, refractive status, and biometric parameters.
METHODS
Ocular dominance was assessed on consenting participants with non-pathological eyes using "hole-in-the-card test." The participants were then examined for visual acuity, biometric measurements, and refraction. Data were analyzed using IBM SPSS software.
RESULTS
Among a total of 660 participants in our study, right eye dominance was found in 508 (76.97%) participants. We found that horizontal keratometry readings (K1) were greater in the dominant eye compared to the non-dominant eye, showing a statistically significant difference in emmetropes (p<0.001) and hyperopes (p<0.001). The axial length was found to be longer but not significantly greater in dominant eye among while it was significant among myopes (p<0.001) and hyperopes (p<0.001). In myopic anisometropes, the axial length was significantly longer and more myopic in the dominant eye (24.0±0.7 mm) than non-dominant eye (23.9±0.4 mm) while the non-dominant eye was more hyperopic in anisometropic hyperopes.
CONCLUSION
Right eye was dominant in majority of participants. The dominant eye was more myopic and had greater axial length in anisometropes. The dominant eye was more astigmatic than the non-dominant eye. Visual acuity was not affected by ocular dominance. The mean difference in biometric measurements was significantly greater in hyperopic eyes. The assessment of ocular dominance could improve patient satisfaction in refractive surgeries and monovision treatments. Treatment protocols could be fine-tuned based on ocular dominance. Normative data in various biometric measurements could take into consideration laterality in terms of dominance.
PubMed: 37521883
DOI: 10.14744/bej.2023.46504 -
Frontiers in Behavioral Neuroscience 2021Social status-dependent modulation of neural circuits has been investigated extensively in vertebrate and invertebrate systems. However, the effects of social status on...
Social status-dependent modulation of neural circuits has been investigated extensively in vertebrate and invertebrate systems. However, the effects of social status on neuromodulatory systems that drive motor activity are poorly understood. Zebrafish form a stable social relationship that consists of socially dominant and subordinate animals. The locomotor behavior patterns differ according to their social ranks. The sensitivity of the Mauthner startle escape response in subordinates increases compared to dominants while dominants increase their swimming frequency compared to subordinates. Here, we investigated the role of the endocannabinoid system (ECS) in mediating these differences in motor activities. We show that brain gene expression of key ECS protein pathways are socially regulated. Diacylglycerol lipase (DAGL) expression significantly increased in dominants and significantly decreased in subordinates relative to controls. Moreover, brain gene expression of the cannabinoid 1 receptor (CBR) was significantly increased in subordinates relative to controls. Secondly, increasing ECS activity with JZL184 reversed swimming activity patterns in dominant and subordinate animals. JZL184 did not affect the sensitivity of the startle escape response in dominants while it was significantly reduced in subordinates. Thirdly, blockage of CBR function with AM-251 had no effect on dominants startle escape response sensitivity, but startle sensitivity was significantly reduced in subordinates. Additionally, AM-251 did not affect swimming activities in either social phenotypes. Fourthly, we demonstrate that the effects of ECS modulation of the startle escape circuit is mediated via the dopaminergic system specifically via the dopamine D1 receptor. Finally, our empirical results complemented with neurocomputational modeling suggest that social status influences the ECS to regulate the balance in synaptic strength between excitatory and inhibitory inputs to control the excitability of motor behaviors. Collectively, this study provides new insights of how social factors impact nervous system function to reconfigure the synergistic interactions of neuromodulatory pathways to optimize motor output.
PubMed: 34045945
DOI: 10.3389/fnbeh.2021.668589 -
Experimental Brain Research Feb 2021Speed accuracy trade-off, the inverse relationship between movement speed and task accuracy, is a ubiquitous feature of skilled motor performance. Many previous studies...
Speed accuracy trade-off, the inverse relationship between movement speed and task accuracy, is a ubiquitous feature of skilled motor performance. Many previous studies have focused on the dominant arm, unimanual performance in both simple tasks, such as target reaching, and complex tasks, such as overarm throwing. However, while handedness is a prominent feature of human motor performance, the effect of limb dominance on speed-accuracy relationships is not well-understood. Based on previous research, we hypothesize that dominant arm skilled performance should depend on visual information and prior task experience, and that the non-dominant arm should show greater skill when no visual information nor prior task information is available. Forty right-handed young adults reached to 32 randomly presented targets across a virtual reality workspace with either the left or the right arm. Half of the participants received no visual feedback about hand position throughout each reach. Sensory information and task experience were lowest during the first cycle of exposure (32 reaches) in the no-vision condition, in which visual information about motion was not available. Under this condition, we found that the left arm group showed greater skill, measured in terms of position error normalized to speed, and by error variability. However, as task experience and sensory information increased, the right arm group showed substantial improvements in speed-accuracy relations, while the left arm group maintained, but did not improve, speed-accuracy relations throughout the task. These differences in performance between dominant and non-dominant arm groups during the separate stages of the task are consistent with complimentary models of lateralization, which propose different proficiencies of each hemisphere for different features of control. Our results are incompatible with global dominance models of handedness that propose dominant arm advantages under all performance conditions.
Topics: Arm; Biomechanical Phenomena; Functional Laterality; Hand; Humans; Movement; Psychomotor Performance; Young Adult
PubMed: 33388816
DOI: 10.1007/s00221-020-06011-6 -
Environmental Monitoring and Assessment Nov 2020A cyclone temporarily disrupts copepod community structure of an estuary, and during the community rebuilding process, omnivorous copepods dominate. This hypothesis was...
A cyclone temporarily disrupts copepod community structure of an estuary, and during the community rebuilding process, omnivorous copepods dominate. This hypothesis was tested after cyclone Fani affected the Ganges River estuary of India on 5 May 2019. Copepod assemblages and environmental parameters were collected before (25 February 2019), after (24 August 2019) and immediately after (daily between 8 and 14 May 2019) cyclone Fani from three sites of the estuary. Immediately after cyclone Fani, spatial heterogeneity of the estuarine environment was washed away, salinity and temperature levels of the estuary increased, pH level declined, while the total dissolve solids remained constant at high levels of concentration. Copepod diversity and abundance were drastically reduced by cyclone Fani with the exception of the omnivorous Bestiolina similis, which tolerated a wide variability of the environment and dominated the community. Led by small and medium-sized copepods, within days, the community recovered from its initial disruption. Immediately after cyclone Fani, medium-sized omnivorous copepod Acartiella tortaniformis became the second most abundant species replacing the small-sized herbivorous Paracalanus parvus. Changes in species composition and abundance hierarchy observed immediately after cyclone Fani lasted for a few months. The intensity of cyclones is increasing in the Indian Sundarban; therefore, following a cyclone, more severe and prolong disruptions of the copepod community are likely. Institutionalized monitoring of the cyclone-mediated ecological changes of the Ganges River estuary is therefore strongly recommended.
Topics: Animals; Copepoda; Cyclonic Storms; Environmental Monitoring; Estuaries; India; Rivers; Salinity
PubMed: 33196930
DOI: 10.1007/s10661-020-08732-1