Cooperation and coordination in heterogeneous populations.

One landmark application of evolutionary game theory is the study of social dilemmas. This literature explores why people cooperate even when there are strong incentives to defect. Much of this literature, however, assumes that interactions are symmetric. Individuals are assumed to have the same strategic options and the same potential pay-offs. Yet many interesting questions arise once individuals are allowed to differ. Here, we study asymmetry in simple coordination games. In our set-up, human participants need to decide how much of their endowment to contribute to a public good. If a group's collective contribution reaches a pre-defined threshold, all group members receive a reward. To account for possible asymmetries, individuals either differ in their endowments or their productivities. According to a theoretical equilibrium analysis, such games tend to have many possible solutions. In equilibrium, group members may contribute the same amount, different amounts or nothing at all. According to our behavioural experiment, however, humans favour the equilibrium in which everyone contributes the same proportion of their endowment. We use these experimental results to highlight the non-trivial effects of inequality on cooperation, and we discuss to which extent models of evolutionary game theory can account for these effects. This article is part of the theme issue 'Half a century of evolutionary games: a synthesis of theory, application and future directions'.

[Exploring and analyzing the improvement mechanism of U-Net and its application in medical image segmentation].

Remarkable results have been realized by the U-Net network in the task of medical image segmentation. In recent years, many scholars have been researching the network and expanding its structure, such as improvement of encoder and decoder and improvement of skip connection. Based on the optimization of U-Net structure and its medical image segmentation techniques, this paper elucidates in the following: First, the paper elaborates on the application of U-Net in the field of medical image segmentation; Then, the paper summarizes the seven improvement mechanism of U-Net: dense connection mechanism, residual connection mechanism, multi-scale mechanism, ensemble mechanism, dilated mechanism, attention mechanism, and transformer mechanism; Finally, the paper states the ideas and methods on the U-Net structure improvement in a bid to provide a reference for later researches, which plays a significant part in advancing U-Net.

Building Flexible Escherichia coli Modules for Bifunctionalizing n-Octanol: The Byproduct of Oleic Acid Biorefinery.

Artificial biorefinery of oleic acid into 1,10-decanedioic acid represents a revolutionizing route to the sustainable production of chemically difficult-to-make bifunctional chemicals. However, the carbon atom economy is extremely low (56%) due to the formation of unifunctional n-octanol. Here, we report a panel of recombinant Escherichia coli modules for diverse bifunctionalization, where the desired genetic parts are well distributed into different modules that can be flexibly combined in a plug-and-play manner. The designed ω-functionalizing modules could achieve ω-hydroxylation, consecutive ω-oxidation, or ω-amination of n-octanoic acid. By integrating these advanced modules with the reported oleic acid-cleaving modules, high-value C8 and C10 products, including ω-hydroxy acid, ω-amino acid, and α,ω-dicarboxylic acid, were produced with 100% carbon atom economy. These ω-functionalizing modules enabled the complete use of all of the carbon atoms from oleic acid (released from plant oil) for the green synthesis of structurally diverse bifunctional chemicals.

APU-Net: An Attention Mechanism Parallel U-Net for Lung Tumor Segmentation.

Lung cancer is one of the malignant tumors with high morbidity and mortality, and lung nodules are the early stages of lung cancer. The symptoms of pulmonary nodules are not obvious in the clinic, and the optimal treatment time is missed due to the missed diagnosis in the clinic. A parallel U-Net network called APU-Net is proposed. Firstly, two parallel U-Net networks are used to extract the features of different modalities. Among them, the subnetwork UNet_B extracts the CT image features, and the subnetwork UNet_A consists of two encoders to extract the PET/CT and PET image features. Secondly, multimodal feature extraction blocks are used to extract features for PET/CT and PET images in UNet_B network. Thirdly, a hybrid attention mechanism is added to the encoding paths of the UNet_A and UNet_B. Finally, a multiscale feature aggregation block is used for extracting feature maps of different scales of decoding path. On the lung tumor 18FDGPET/CT multimodal medical images dataset, experiments' results show that the DSC, Recall, VOE, and RVD coefficients of APU-Net are 96.86%, 97.53%, 3.18%, and 3.29%, respectively. APU-Net can improve the segmentation accuracy of the adhesion between the lesion of complex shape and the normal tissue. This has positive significance for computer-aided diagnosis.

Carving the Active Site of CYP153A7 Monooxygenase for Improving Terminal Hydroxylation of Medium-Chain Fatty Acids.

The P450-mediated terminal hydroxylation of non-activated C-H bonds is a chemically challenging reaction. CYP153A7 monooxygenase, discovered in Sphingomonas sp. HXN200, belongs to the CYP153A subfamily and shows a pronounced terminal selectivity. Herein, we report the significantly improved terminal hydroxylation activity of CYP153A7 by redesign of the substrate binding pocket based on molecular docking of CYP153A7-C8:0 and sequence alignments. Some of the resultant single mutants were advantageous over the wild-type enzyme with higher reaction rates, achieving a complete conversion of n-octanoic acid (C8:0, 1 mM) in a shorter time period. Especially, a single-mutation variant, D258E, showed 3.8-fold higher catalytic efficiency than the wild type toward the terminal hydroxylation of medium-chain fatty acid C8:0 to the high value-added product 8-hydroxyoctanoic acid.

Deciphering Neurodegenerative Diseases Using Long-Read Sequencing.

Neurodegenerative diseases exhibit chronic progressive lesions in the central and peripheral nervous systems with unclear causes. The search for pathogenic mutations in human neurodegenerative diseases has benefited from massively parallel short-read sequencers. However, genomic regions, including repetitive elements, especially with high/low GC content, are far beyond the capability of conventional approaches. Recently, long-read single-molecule DNA sequencing technologies have emerged and enabled researchers to study genomes, transcriptomes, and metagenomes at unprecedented resolutions. The identification of novel mutations in unresolved neurodegenerative disorders, the characterization of causative repeat expansions, and the direct detection of epigenetic modifications on naive DNA by virtue of long-read sequencers will further expand our understanding of neurodegenerative diseases. In this article, we review and compare 2 prevailing long-read sequencing technologies, Pacific Biosciences and Oxford Nanopore Technologies, and discuss their applications in neurodegenerative diseases.

The ensemble deep learning model for novel COVID-19 on CT images.

The rapid detection of the novel coronavirus disease, COVID-19, has a positive effect on preventing propagation and enhancing therapeutic outcomes. This article focuses on the rapid detection of COVID-19. We propose an ensemble deep learning model for novel COVID-19 detection from CT images. 2933 lung CT images from COVID-19 patients were obtained from previous publications, authoritative media reports, and public databases. The images were preprocessed to obtain 2500 high-quality images. 2500 CT images of lung tumor and 2500 from normal lung were obtained from a hospital. Transfer learning was used to initialize model parameters and pretrain three deep convolutional neural network models: AlexNet, GoogleNet, and ResNet. These models were used for feature extraction on all images. Softmax was used as the classification algorithm of the fully connected layer. The ensemble classifier EDL-COVID was obtained via relative majority voting. Finally, the ensemble classifier was compared with three component classifiers to evaluate accuracy, sensitivity, specificity, F value, and Matthews correlation coefficient. The results showed that the overall classification performance of the ensemble model was better than that of the component classifier. The evaluation indexes were also higher. This algorithm can better meet the rapid detection requirements of the novel coronavirus disease COVID-19.

Facile fabrication of porous BiVO4 hollow spheres with improved visible-light photocatalytic properties.

Bismuth vanadate (BiVO4) hollow spheres with porous structure have been successfully fabricated by a one-step wet solution method with no surfactant and template. The structure, morphologies, and composition of the as-prepared products were studied with X-ray powder diffraction (XRD), transmission electron morphology (TEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS) and UV-vis spectroscopy. Based upon the time-dependent experimental results, BiVO4 nanospheres with hollow and solid structures can be controlled effectively through the reaction time, and a reasonable formation process was suggested in this work. Moreover, the experiment of degrading methyl orange (MO) under visible-light illumination was conducted to evaluate the photocatalytic performance of the obtained BiVO4 samples. The porous BiVO4 hollow spheres exhibit superior visible-light photocatalytic properties for MO degradation than other photocatalysts under irradiation, and could be reused for up to five times without significant reduction in the photocatalytic activity. In addition, based on active group trapping experiments, ˙OH radicals as the main active species from H2O2 molecules play a vital role in the photocatalytic degradation of MO, and a photocatalytic mechanism for the BiVO4 system was proposed. High photocatalytic activity, universality and stability suggest that the porous BiVO4 hollow spheres may have potential applications in wastewater treatment.

One-pot preparation of hierarchical Cu2O hollow spheres for improved visible-light photocatalytic properties.

As visible light photocatalysts, narrow bandgap semiconductors can effectively convert solar energy to chemical energy, exhibiting potential applications in alleviating energy shortage and environmental pollution. Cu2O hollow spheres with a narrow band gap and uniform hierarchical structures have been fabricated in a controlled way. The one-pot solvothermal method without any template is simple and facile. The morphologies, crystal structures, composition, specific surface areas, and optical and photoelectric properties of the products were analyzed by various techniques. The hollow and solid Cu2O spheres could be fabricated by controlling the reaction time, and a possible growth process of the Cu2O hollow spheres was revealed. The degradation of methyl orange (MO) was used to investigate the visible-light catalytic properties of the Cu2O samples. More than 90% of MO is degraded under visible light illumination of 20 min, exhibiting a quick catalytic reaction. The rate constant of the Cu2O hollow spheres was 2.54 times and 46.6 times larger than those of the Cu2O solid spheres and commercial Cu2O powder, respectively. The possible photocatalytic mechanism of MO was revealed over Cu2O hollow spheres through the detection of active species. The as-prepared Cu2O hollow spheres display improved visible-light catalytic activity and stability, indicating their potential application in wastewater treatment.

The competitive advantage of institutional reward.

Sustaining cooperation among unrelated individuals is a fundamental challenge in biology and the social sciences. In human society, this problem can be solved by establishing incentive institutions that reward cooperators and punish free-riders. Most of the previous studies have focused on which incentives promote cooperation best. However, a higher cooperation level does not always imply higher group fitness, and only incentives that lead to higher fitness can survive in social evolution. In this paper, we compare the efficiencies of three types of institutional incentives, namely, reward, punishment, and a mixture of reward and punishment, by analysing the group fitness at the stable equilibria of evolutionary dynamics. We find that the optimal institutional incentive is sensitive to decision errors. When there is no error, a mixture of reward and punishment can lead to high levels of cooperation and fitness. However, for intermediate and large errors, reward performs best, and one should avoid punishment. The failure of punishment is caused by two reasons. First, punishment cannot maintain a high cooperation level. Second, punishing defectors almost always reduces the group fitness. Our findings highlight the role of reward in human cooperation. In an uncertain world, the institutional reward is not only effective but also efficient.

New Insights Into the Pathogenesis of Alzheimer's Disease.

Alzheimer's disease (AD), a common neurodegenerative disease in the elderly and the most prevalent cause of dementia, is characterized by progressive cognitive impairment. The prevalence of AD continues to increase worldwide, becoming a great healthcare challenge of the twenty-first century. In the more than 110 years since AD was discovered, many related pathogenic mechanisms have been proposed, and the most recognized hypotheses are the amyloid and tau hypotheses. However, almost all clinical trials targeting these mechanisms have not identified any effective methods to treat AD. Scientists are gradually moving away from the simple assumption, as proposed in the original amyloid hypothesis, to new theories of pathogenesis, including gamma oscillations, prion transmission, cerebral vasoconstriction, growth hormone secretagogue receptor 1α (GHSR1α)-mediated mechanism, and infection. To place these findings in context, we first reviewed the neuropathology of AD and further discussed new insights in the pathogenesis of AD.

An etching based fluorescent probe for sensitive detection of hydrogen sulfide in cells.

Hydrogen sulfide (H2S) is one of the most crucial gas signaling agents that mediate many physiological and pathological processes. However, rapid high-efficiency detection and imaging of H2S in living cells is very challenging. Herein we reported a simple fluorescent nanoprobe using FAM-DNA/AgNP nanocomposites for fast and sensitive H2S detection based on surface silver displacement. In contrast to the conventional principles for fluorescence turn-on analyte detection, the present work demonstrated a sensitive and selective AgNP based optosensor for the assay of H2S. Compared with the majority of the reported H2S probes, complex synthesis procedures and costly equipment are not involved in this assay.

The dynamics of human behavior in the public goods game with institutional incentives.

The empirical research on the public goods game (PGG) indicates that both institutional rewards and institutional punishment can curb free-riding and that the punishment effect is stronger than the reward effect. Self-regarding models that are based on Nash equilibrium (NE) strategies or evolutionary game dynamics correctly predict which incentives are best at promoting cooperation, but individuals do not play these rational strategies overall. The goal of our study is to investigate the dynamics of human decision making in the repeated PGG with institutional incentives. We consider that an individual's contribution is affected by four factors, which are self-interest, the behavior of others, the reaction to rewards, and the reaction to punishment. We find that people on average do not react to rewards and punishment, and that self-interest and the behavior of others sufficiently explain the dynamics of human behavior. Further analysis suggests that institutional incentives promote cooperation by affecting the self-regarding preference and that the other-regarding preference seems to be independent of incentive schemes. Because individuals do not change their behavioral patterns even if they were not rewarded or punished, the mere potential to punish defectors and reward cooperators can lead to considerable increases in the level of cooperation.

Evolution of Conformity in Social Dilemmas.

People often deviate from their individual Nash equilibrium strategy in game experiments based on the prisoner's dilemma (PD) game and the public goods game (PGG), whereas conditional cooperation, or conformity, is supported by the data from these experiments. In a complicated environment with no obvious "dominant" strategy, conformists who choose the average strategy of the other players in their group could be able to avoid risk by guaranteeing their income will be close to the group average. In this paper, we study the repeated PD game and the repeated m-person PGG, where individuals' strategies are restricted to the set of conforming strategies. We define a conforming strategy by two parameters, initial action in the game and the influence of the other players' choices in the previous round. We are particularly interested in the tit-for-tat (TFT) strategy, which is the well-known conforming strategy in theoretical and empirical studies. In both the PD game and the PGG, TFT can prevent the invasion of non-cooperative strategy if the expected number of rounds exceeds a critical value. The stability analysis of adaptive dynamics shows that conformity in general promotes the evolution of cooperation, and that a regime of cooperation can be established in an AllD population through TFT-like strategies. These results provide insight into the emergence of cooperation in social dilemma games.

[Study on ultrastructure of cardioprotection of ramipril against ischemia/reperfusion injury in diabetic rats].

AIM: To investigate the effects of ramipril on myocardial ischemia/reperfusion injury in diabetic rats, and to explore its mechanism according to the observation on myocardial ultrastructure. METHODS: Streptozotocin induced diabetic rats were divided randomly into three groups (n = 16): ischemia/reperfusion (I/R), ischemic preconditioning (IPC) and ramipril (RAM) group. Rats in RAM group were administered by RAM(1 mg x kg(-1) x d(-1)) orally for 4 weeks, the others were administered by normal saline. Then all rats were subjected to myocardial ischemia/ reperfusion injury. Rats in IPC group were preconditioned before ischemia. The ECG and the infarct size were examined. The changes of myocardial morphology were examined by light and electron microscopes. RESULTS: Compared with I/R group, the elevation of ST segment and the incidence of ventricular tachycardia and ventricular fibrillation during ischemia were significantly decreased, the infarct size at the end of reperfusion was remarkably reduced, the myocardial morphology were significantly improved, special structure of myofilaments and mitochondria remained clearly, blood vessels were unobstructed, injury of endothelium were decreased in PC and RAM groups. CONCLUSION: Ramipril administered for 4 weeks induces myocardial protection in diabetic rats, which is similar to that of IPC. The mechanism may be involved in protection of cardiocytes and mitochondria, and improvement of endothelial function.

[Evaluation of midazolam intravenous sedated patient's comfort degree in mandibular third molar surgery].

OBJECTIVE: To evaluate the clinical efficacy and safety of continuous low-flow intravenous infusion of midazolam sedation in mandibular third molar surgery. METHODS: Fifty healthy patients with symmetrically placed impacted bilateral mandibular third molars were included in this self controlled, randomized clinical study. Degree of comfort (their actual current anxiety level) was assessed using a visual analogue scale (VAS) of pain and anxiety. Patients' satisfaction and degree of amnesia were also evaluated. Vital signs and oxygen saturation were recorded. RESULTS: Low dose midazolam sedation obviously increased the degree of patients' comfort and satisfaction. Vital signs and oxygen saturation levels did not differ significantly between the two groups. CONCLUSIONS: Midazolam as an intravenous sedation agent in mandibular third molar surgery showed satisfactory effect on patients with mild dental fear.

[Morphologic observation of papaya on anoxic damaged cerebral neurocytes of therapeutic efficacy in vitro].

OBJECTIVE: To observe the effects of papaya on the therapeutic efficacy of cerebral neurocytes following anoxic damage in vitro. METHODS: The rat embryonic cerebral neurocytes were cultured with serum-free medium. Papapa was added in while anoxic damage occurred and the neurocytes were divided into four groups (group I-anoxic damage 0 mg/ml, group II-anoxic damage 0.1 mg/ml, group III-anoxic damage 0.5 mg/ml and group-IV non-anoxic damage 0 mg/ml). At the end of the experiment, cultured neurocytes were collected and biochemical indexes were detected and, a pathological observation was made by using electronic microscope. RESULTS: The activity of MTT in group II was significantly higher than that in the other three groups(P < 0.01). Compared with group I and IV, the level of TCHE in group II and III was increased significantly(P < 0.05), and the level of TCHE in group III was much higher than that in group II (P < 0.05). The morphological observation showed that the number of neurocytes in group I decreased, and the appearance of cell was broken, the outer limits were not clear, apophysises were thin and short, and apoptosis body can be found. In group II and III, stretched preparation of majority cells was good, the bodies of neurocytes was full-grown, the outer limits were clear, apophysises were strong and network was dense, chromatin was partly condense, but apoptosis bodies can not be found. CONCLUSION: Papaya can promote the recovery of anoxic damage of rat cerebral neurocytes in structure.

[An analysis of adhered cells on the surface of F-heparin surface modified intraocular lenses implanted into rhesus monkeys' eyes].

OBJECTIVE: To study the biocompatibility of F-heparin surface modified intraocular lenses (IOLs) by observing cellular reaction on the surface of IOLs implanted into the rhesus monkeys' eyes. METHODS: Ten monkeys (20 eyes) were classified into two groups. PMMA IOLs and F-heparin modified IOLs were respectively implanted into 10 monkeys' eyes. The IOLs were examined with computer image analysis, light microscope (LM) and scanning electron microscope (SEM) at postoperative 180 and 360 days. RESULTS: A few of adhered cells were on the surface of the central part of the IOL and more on the border of the IOL optics. The giant cells deposited on the surface occupied the largest area and the number of the macrophages was the greatest. The cells deposited on the surface of the IOLs in the F-heparin modified group were less than that in the non-modified group. In the modified group, there was fine granular proteinaceous membrane on the surface of the IOLs, but in the non-modified group there was fibrinous reticular proteinaceous membrane. CONCLUSION: The biocompatibility of the F-heparin surface modified IOLs is better than that of non-modified PMMA IOLs.