Metro driver is the prime person who is responsible for metro operation safety. The mental health of a metro driver is very important for the operation of the subway and requires the driver to keep high mental alertness to monitor the surrounding environment and also handle emergencies under uncertain or dangerous conditions. After a long-term occupational strain, a metro driver is likely to suffer from some mental health problems, such as anxiety and depression, that ultimately threaten the lives of passengers. Therefore, in this study, we focus on the psychological symptoms of metro drivers from the angle of occupational strain and neuroticism. A total of 396 metro drivers from Kunming Rail Transit Operation Co., Ltd. in China were investigated through a questionnaire survey. Symptom Checklist-90 (SCL-90), Personal Strain Questionnaire (PSQ), and NEO-Five-Factor Inventory-Neuroticism Subscale (NEO-FFI-N) were applied to evaluate the psychological symptoms, occupational strain, and neuroticism in metro drivers, respectively. The surveyed data were analyzed by SPSS software. Based on the data, a path structural equation model was established to explore the correlation among occupational strain, psychological symptoms, and neuroticism. The results show that the scores for psychological symptoms and occupational strain are higher than the Chinese adult norm among metro drivers. The occupational strain, neuroticism, and psychological symptoms are all positively correlated in the metro drivers. Occupational stress has a direct influence on the psychological symptom, while neuroticism plays a partial mediation role between occupational strain and psychological symptoms. The results of this study can be applied to optimize the employee selection system and training system for metro operation companies. Subway train operation is a complex and socio-technical system that requires the metro driver to keep high mental alertness to monitor the surrounding environment and also handle emergencies instantaneously under dangerous conditions. In such a high-intensive and persistent job environment, metro drivers not only endure the pressure related to the job, but also need to overcome the fatigue and languor caused by high-intensive work. Therefore, after working for a long term, chronic mental stress will produce a negative impact on the physical and mental health of metro drivers. In addition, the subway train operation not only requires that the metro driver has a good professional quality to realize the modernization operation, but also requires the metro driver to bear the repetitive dry operation and boring working environment which will undoubtedly lead to the occurrence of adverse psychological symptoms among the metro drivers. With the improvement of automation, the errors caused by machines rarely occur in subway operations. On the contrary, human operation error has gradually become the main cause of driving accidents, and most of the accidents are caused by the unsafe behavior of humans, which is further related to psychological factors. Therefore, the mental health of metro drivers directly affects the safety of thousands of passengers and the service quality of trains.Many studies have focused on transportation accidents and analyzing the causes of the accident . Most reSome studies have also found that personality also has a significant influence on driving safety. In previous studies , the autThrough literature analysis, it has been found that occupational strain and neuroticism can affect individual psychological symptoms, and high occupational strain can lead to neuroticism . TherefoThe rest of this paper is organized as follows: Section II provides details about the study subjects, tools used, and statistical methods. Section III addresses the data analysis results. Section IV presents the results and discussion. Finally, Section V includes the conclusion and summary.In this study, a total of 417 on-the-job metro drivers from Kunming Rail Operation Co., Ltd. in Yunnan Province of China were selected to conduct a questionnaire survey and collect data regarding occupational strain, psychological symptoms, and neuroticism. The questionnaire survey was approved by Kunming Rail Transit Operation Co., Ltd. Since Kunming Rail Transit Operation Co., Ltd. does not have an established ethics review committee at present, all the research procedures were approved by the company. Prior to the survey, the metro drivers with mental illness or other brain organic lesions were eliminated through their personal records and annual physical examination reports from the company. Before the survey, the metro drivers were informed about the following conditions: (1) If they decided to participate in this survey, their personal information would be kept confidential and the information will be accessible only to them; (2) when the survey results are published, their personal information will be not disclosed; and (3) all on-the-job metro drivers need to sign an informed consent form. The survey was conducted from April 2021 to July 2021. All methods were performed in accordance with relevant guidelines and regulations that include Revised Declaration of After the survey, 21 invalid questionnaires were excluded, and 396 valid questionnaires were recovered with an effective rate of 94.96%. The data were analyzed based on the statistical parameters of the interviewees. All the 396 metro drivers included in the study were male, with 105 being undergraduates and 204 having college degrees, 85 secondary school degrees, and two high school degrees. A total of 141 metro drivers were married, while 255 were unmarried. The mean age of drivers was 25.6 ± 3.0 years, with an age range of 19–44 years. The description of the study participants is presented in The Symptom Checklist-90 (SCL-90), proposed by The Chinese version of the Occupational Stress Inventory-Revised Edition (OSI-R) proposed by The Chinese version of the NEO-Five-Factor Inventory-Neuroticism Subscale (NEO-FFI-N) was used to measure the neuroticism among the metro drivers in this study. The test table was compiled by t-test was used to evaluate whether the correlation between the psychological symptoms and occupational strain was significant among the metro drivers, and a decreasing p-value is an indicator of the credibility of the result that is used to evaluate the reasonability of hypothesis testing. A small p-value indicates reliable results. Pearson’s correlation analysis is used to measure the correlation between psychological symptoms, occupational strain, and neuroticism in metro drivers. The range of r is . When r < 0, there is a linear negative correlation between the two variables. When r > 0, there is a linear positive correlation between the two variables. When r = 0, there is no obvious correlation between the two variables. Finally, an intermediary model is proposed in the study to explore the relationship between psychological symptoms, occupational strain, and neuroticism among metro drivers by combining the path analysis method and bootstrapping method.In this study, the data obtained by questionnaire survey were analyzed using SPSS 25.0 software developed by Norman and Hadleigh . This soFor sociology and behavioral research, it is necessary to evaluate the reliability and validity of the questionnaires by analyzing the collected data. In this study, SPSS software was applied to analyze the reliability of questionnaires. In general, Cronbach’s α coefficient is used to evaluate the reliability of questionnaires. The value of the Cronbach’s α coefficient can reflect the degree of internal consistency of questionnaires. Higher Cronbach’s α coefficient indicates a stable questionnaire structure. When the Cronbach’s α-value is below 0.6, the reliability of the questionnaire is poor. When the Cronbach’s α-value is between 0.6 and 0.7, the reliability of the questionnaire is acceptable. When the Cronbach’s α-value is greater than 0.7, the questionnaire has good reliability. In this survey, the reliability of SCL-90, PSQ, and NEO-FFI-N is presented in The validity of a questionnaire refers to whether the questionnaire can accurately detect the problem being measured. However, before evaluating the validity of the questionnaire, it is necessary to test whether the questionnaire is suitable for factor analysis. In general, Kaiser–Meyer—Olykin Measure of Sampling Adequacy (KMO) and Barlett’s test of sphericity are applied to evaluate whether the questionnaire is suitable for factor analysis. When KMO < 0.7, it means that the questionnaire is not suitable for factor analysis. When 0.7 < KMO < 0.8, factor analysis can be performed. When KMO > 0.8, it means that the questionnaire is suitable for factor analysis. At the same time, when the significant probability of Barlett’s sphericity test is less than 0.05, it means that the questionnaire can be extracted by the factor method to simplify the data structure. When the KMO value and Barlett’s sphericity test for the questionnaire meet the requirements at the same time, it means that factor analysis can be performed. Validity of the questionnaire mainly refers to construct validity which is the measured values explanation degree of psychological trait of participants. The construct validity of the questionnaire includes convergent validity and discriminant validity. In this study, composite reliability (CR) and average variance extracted (AVE), proposed by In this study, the psychological symptom scale and the occupational strain scale are multi-dimensional and hence need to be tested for discriminant validity. The discriminant validity of these questionnaires is evaluated by calculating the square root of the AVE value. If the square root of the AVE value is greater than the correlation coefficient value of each dimension, the discriminant validity of the questionnaire is excellent. The diagonal values in p < 0.01). This indicates that the work of metro drivers mainly affects somatization, and the nature of work can easily induce a nervous emotion in metro drivers, thus resulting in negative psychological symptoms, such as compulsion, hostility, and psychosis. The score for interpersonal relationships is similar to the Chinese adult norm. This means that the work of metro drivers has little influence on interpersonal relationships. The total score of the metro driver is also significantly higher than the Chinese adult norms (148.84 ± 42.66) (p < 0.01). This indicates that the psychological symptoms are not optimistic in metro drivers. It is suggested that metro drivers should strengthen physical exercise to improve their physical fitness. In addition, metro drivers should always adjust their mentality through cultivating hobbies or communicating with family and friends.p < 0.01). This indicates that the work intensity of metro drivers is greater than that observed in other occupations, and long-term work has an adverse effect on their business capabilities and physical health. The psychological strain of metro drivers is also higher than the Chinese adult norm. This means that metro drivers get easily nervous during work. The total score of the metro driver is also significantly higher than the Chinese adult norm (104.17 ± 14.18) (p < 0.01). The results show that the individual adaptability of most metro drivers cannot help them achieve a good balance of the job content.r) of each dimension in the SCL-90, PSQ, and NEO-FFI-N. It can be found that the neuroticism and psychological symptoms of metro drivers are significantly correlated with their occupational strain . The occupational strain of metro drivers is positively correlated with psychological symptoms . Neuroticism is positively correlated with psychological symptoms , and it is positively correlated with occupational strain . It can also be observed from other correlation coefficients that the various dimensions in scales are also positively correlated with each other, with r from 0.10 to 0.93, and all p < 0.05. This result indicates that the psychological symptom of metro drivers is mainly affected by occupational strain and neuroticism, but their influence mechanism is not clear and needs to be further investigated.To determine the main factor that influences the mental health of metro drivers, the correlation among occupational strain, neuroticism, and psychological symptoms is investigated. In this study, in order to further find the influence path among neuroticism, occupational strain, and psychological symptom, a path structural equation model is established using Amos24.0 software , as show2/df), the goodness-of-fit index (GIF), normed fit index (NFI), comparative fit index (CFI), Tucker-Lewis (TLI), relative goodness-of-fit indices (RFI), and root-mean-square error of approximation (RMSEA). If the fit indices are within the recommended values, the model is valid. Before performing correlation analysis, the path structural equation model must be validated. In general, the structural equation model can be validated by evaluating fit indices of chi-square to freedom ratio (χp < 0.01), we can conclude that the occupational stain is strongly associated with psychological symptoms. The level of occupational strain in metro drivers can positively predict their psychological symptoms, and high occupational strain causes severe psychological symptoms. From the β-value in sub-model B, it can be found that the occupational strain of metro drivers has a significant positive predictive effect on the neuroticism  and psychological symptom , and the neuroticism had a significantly positive predictive effect on psychological symptom . After adding neuroticism as an intermediary in sub-model B, the direct predictive effect of occupational strain on the psychological symptom of metro drivers is decreased from β = 0.52 to β = 0.34. This indicates that neuroticism has a mediating effect between occupational strain and psychological symptoms.b = 0.03, 95% CI ), and the mediating effect value is 0.187, accounting for 34.89% of the total effect. The result indicates that the neuroticism of metro drivers has a partial mediating effect between the occupational strain and psychological symptoms.To verify whether the mediating effect of neuroticism between occupational strain and psychological symptoms is significant or not, bootstrapping analysis was used to construct confidence intervals, to verify the significance of the mediation effect through analyzing the scores of 5,000 duplicate samples from 396 samples. The scores need to be judged according to the 95% confidence interval obtained by the bootstrap method. The lower confidence interval (LLCI) and the upper confidence interval (ULCI) do not contain 0 or possess the same symbol, that is, both values are negative or positive. If it is positive, it means that the parameter is statistically significant at the 0.05 level. Otherwise, if it contains 0, or an opposite symbol, it means that the parameter is not significant. In this study, we focus on the psychological symptoms among metro drivers from the angle of occupational strain and neuroticism. A total of 396 metro drivers from Kunming Rail Transit Operation Co., Ltd. in China were investigated through a questionnaire survey. SCL-90, PSQ, and NEO-FFI-N were applied to evaluate the psychological symptoms, occupational strain, and neuroticism in metro drivers, respectively. The surveyed data were analyzed by SPSS software, and based on the data, a path structural equation model was established to explore the correlation among occupational strain, psychological symptoms, and neuroticism. The main conclusions of this study are given in the following section.p-value < 0.01. This result is similar to that reported by p < 0.01). The results indicate that the mental health status of metro drivers is not optimistic. The metro drivers are likely to cause serious safety issues under a long-term fear of operating errors, excessive tension, chronic anxiety, and diffuse anxiety. Repeated and monotonous operating procedures can easily lead to somatization, paranoia, and other psychopathological symptoms in metro drivers. The closed and narrow working environment can make the metro driver feel at a loss in the event of an emergency and take wrong decisions in a panic  determined by SCL-90 are significantly higher than the Chinese adult norm (129.96 ± 38.76) in metro drivers, especially for the scores of somatization, compulsion, depression, anxiety, hostility, terror, crankiness, and psychopathy, with all the symptoms having a  a panic .p < 0.05). That is, the higher the occupational strain for metro drivers, the more obvious the psychological symptom. Neuroticism in metro drivers is also significantly positively correlated with occupational strain and psychological symptoms (p < 0.05). These results indicate that the neuroticism in metro drivers can positively predict their mental health and occupational strain.Second, the occupational strain among metro drivers is significantly positively correlated with psychological symptoms  is established in AMOS software to further analyze the relationship among occupational strain, psychological symptoms, and neuroticism. The result shows that the direct effect of occupational strain on psychological symptoms is significant, and that neuroticism plays a mediating effect between occupational strain and psychological symptoms. The study result can provide a theoretical foundation for the metro operating companies to optimize the workflow for metro drivers.Since this study only investigated the metro drivers of Kunming Metro Operation Co., Ltd., the sample is single and unrepresentative, and the research is still insufficient. In the future, the sample size can be expanded to conduct investigation and research on subway enterprises in different regions and different management levels. Relevant intervention strategies will also be formulated at the organizational and individual levels to improve the safety level of subway operations.The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.Ethical review and approval was not required for the study on human participants in accordance with the local legislation and institutional requirements. The patients/participants provided their written informed consent to participate in this study.JH and YZ: conceptualization and writing of the original draft. JH and SQ: methodology. YZ: software. JH, YZ, and WL: formal analysis, writing, reviewing, and language modification. All authors have read and agreed to the publication of the manuscript.WL was employed by the Kunming Rail Transit Operation Co., Ltd. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


Pathogens are important threats to many plants throughout their lifetimes. Plants have developed different strategies to overcome them. In the plant immunity system, nucleotide-binding domain and leucine-rich repeat-containing proteins (NLRs) are the most common components. And recent studies have greatly expanded our understanding of how NLRs function in plants. In this review, we summarize the studies on the mechanism of NLRs in the processes of effector recognition, resistosome formation, and defense activation. Typical NLRs are divided into three groups according to the different domains at their N termini and function in interrelated ways in immunity. Atypical NLRs contain additional integrated domains (IDs), some of which directly interact with pathogen effectors. Plant NLRs evolve with pathogen effectors and exhibit specific recognition. Meanwhile, some NLRs have been successfully engineered to confer resistance to new pathogens based on accumulated studies. In summary, some pioneering processes have been obtained in NLR researches, though more questions arise as a result of the huge number of NLRs. However, with a broadened understanding of the mechanism, NLRs will be important components for engineering in plant resistance improvement. A large number of microbes are pathogens for plants, which cause different kinds of diseases. However, plants have developed many strategies to acquire resistance to most of the pathogens after a long time of evolution. It is well known that there are two layers of innate immunity in plants. The first layer is composed of membrane-anchored receptors that can interact with small conserved molecules called pathogen-associated molecular patterns (PAMPs) or microbe-associated molecular patterns (MAMPs). Therefore, these receptors are named as pattern recognition receptors (PRRs) and initiate PAMP-triggered immunity (PTI)  gene or a pair of related R genes, in a few cases, in plants. The R genes can confer resistance to pathogens that carry avirulence (avr) genes in the way known as the “gene for gene” hypothesis. Meanwhile, quantitative resistance is controlled by multiple different genes or loci in the genome. Usually, qualitative resistance is pathogen race-specific and can be even complete resistance, while quantitative resistance is pathogen race-nonspecific and partial resistance. Qualitative resistance is also simple and easy to manipulate. As a result, it is widely used in mechanism studies and crop improvement. To date, the number of cloned plant R genes is more than 300 , which are also the most common intracellular receptors in ETI  domain and a leucine-rich repeat (LRR) domain. The N-termini of the typical NLRs are different, but only a few domains or motifs exist in this region, such as the Toll/interleukin receptor (TIR) domain, coiled-coil (CC) motif, or resistance to powdery mildew 8 (RPW8) domain. Based on these domains, the typical NLRs can be grouped into three groups, TIR-NLRs (TNLs), CC-NLRs (CNLs), and RPW8-NLRs (RNLs) , such as WRKY, kinase, heavy metal-associated (HMA), and zinc-finger BED (zf-BED) domains  and PBS1, which are involved in the resistance mediated by many NLRs  exists at the terminus of the CNL Sw-5. The Sw-5 SD physically interacts with a conserved region in the viral movement protein NSm from tospoviruses and activates Sw-5 to initiate a defense response  last year , and cell death in plants  accumulation and HR in Arabidopsis   through its TIR domain in an indirect manner. The N receptor-interacting protein 1 (NRIP1) interacts with both N and p50 and forms a complex in plant defense response , cyclization variant of cADPR (v-cADPR), and nicotinamide (NAM) , which belonged to Toll-like receptor (TLR) proteins. The SARM1-TIR domain has intrinsic NADase (nicotinamide adenine dinucleotide nucleosidase) activity and contains an essential glutamic acid residue  family and the NRG1 (N REQUIREMENT GENE 1) family  family, which contains EDS1, PAD4 , and SAG101 (senescence-associated gene 101)  DC3000 in Arabidopsis. Given that the TNL-encoding gene Roq1 does not exist in the Arabidopsis genome, NRG1 is considered to recognize the effector HopQ1 directly , which causes a rapid influx of CaRalstonia solanacearum and AvrRps4 from Pseudomonas syringae pv. pisi  can interact with the WRKY domain of RRS1-R1  effector family  domains as integrated decoys. In a few pieces of literature, the “executor NLR” is also called “helper NLR”  and Xanthomonas oryzae pv. oryzicola (Xoc) . R3a recognizes the effector AVR3a of P. infestans but responds weakly to its allele AVR3aEM. A random mutant library has been generated and many clones with expanded responses to AVR3aEM have been obtained  .The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.


We quantify Non Fungible Token (NFT) rarity and investigate how it impacts market behaviour by analysing a dataset of 3.7M transactions collected between January 2018 and June 2022, involving 1.4M NFTs distributed across 410 collections. First, we consider the rarity of an NFT based on the set of human-readable attributes it possesses and show that most collections present heterogeneous rarity patterns, with few rare NFTs and a large number of more common ones. Then, we analyze market performance and show that, on average, rarer NFTs: (i) sell for higher prices, (ii) are traded less frequently, (iii) guarantee higher returns on investment, and (iv) are less risky, i.e., less prone to yield negative returns. We anticipate that these findings will be of interest to researchers as well as NFT creators, collectors, and traders. Throughout 2021, the NFT market grew by more than 61,000%, starting from a monthly sale volume of 8,072,866 USD in January 2021 to 4,968,834,938 USD in January 202210. NFT was Collins Dictionary’s word of the year for 202111.Non Fungible Tokens, or NFTs, are digital titles (tokens) to property, either real or virtual, stored on a blockchain. They offer a powerful solution to long-standing issues related to the ownership of virtual and physical assets. They have swiftly revolutionised the art market12. They have been a driving force for the booming NFT market13. In the prominent case of generative art, NFTs are associated to  objects made using a predetermined system, typically an algorithm, that often includes an element of chance14. To be concrete, CryptoPunks is a collection of 10,000 unique images of pixelated human faces algorithmically generated15, while Bored Ape Yacht Club contains 10,000 profile pictures of cartoon apes that are generated by an algorithm16. Their market capitalization is 834M USD and 1.2B USD as of June 2022, respectively17.NFT collections are groups of NFTs that share common features, such as visual aspects or the code that generated themtraits that distinguish them. So a punk can have, or not have, a “Top Hat”, a “Red Mohawk”, a “Silver Chain”, or “Wild White Hair” among other possibilities. Furthermore, while most CryptoPunks are humans, there are also 88 Zombies, 24 Apes, and 9 Aliens in the collection. CryptoPunks are not equivalent according to the market. The most expensive CryptoPunk to date was sold for 23.7 million USD on February 12, 202218, despite the average price of a punk being “only” 138,179 USD . A similar picture holds for Bored Apes, with the most expensive one traded for 3.4 million USD on October 26, 202120, vs an average price of 48,836 USD.NFTs in a collection are most often distinguishable from one another. For example, CryptoPunks have a gender  and—as for many other collections—a number of 24. However, despite some evidence that rarity and aesthetic preferences do play a role in the case of CryptoPunks25, a comprehensive analysis of the role of rarity on the market of NFTs is still lacking.An hypothesis to rationalise these differences in price considers rarity. The heterogeneous distribution of traits among NFTs make some of them more rare than others see Fig. , and sca17. Our dataset describes the rarity of 410 collections listed on OpenSea, containing a total of 1,479,020 NFTs that were exchanged 3,775,040 times between January 23, 2018 and June 6, 2022. First, we characterise trait distributions and investigate how they impact NFT rarity. Then, we analyse transaction data and find that: (i) rarity positively correlates with NFT prices and return on investments (ROIs), and (ii) negatively correlate with number of sales and risk quantified as the likelihood of a negative ROI. The breadth of our analysis suggests this market behaviour is likely to be genuinely self-organised. At the same time, our results could inform further research aimed at establishing how to optimally design collections, as well as effective trading strategies for the NFT market.In this paper, we carry out a systematic investigation of how the rarity of NFTs impacts their market behaviour. We focus on within-collection rarity using the definition proposed in the platform rarity.tools9, as well as of the underlying technologies, such as the blockchain and the smart contracts, with a risk assessment26. Other research has focused generally on specific marketplaces or collections, analysing such issues as the determinants of success of NFT artists27, the role of social media attention28, the creators-collectors network29, and the financial advantage of experienced users30. Along this line, research also suggests that NFTs have become a promising investment as a fintech asset31. Other lines of research include the analysis of illicit transactions connected to NFT trading33 and of their connections with financial indicators36. The metaverse, an NFT submarket which has recently garnered attention both from big tech companies37 and popular NFT creators38, is another focus of research40.Our work adds to the relatively small yet rapidly growing body of research on the NFT ecosystem. Previous studies include an overview of the overall market, trade networks, and visual features of NFTs, and their impact on price predictionNFTs An NFT—or Non Fungible Token—is a unit of data stored in a blockchain that certifies a digital asset to be unique and not interchangeable. It provides uncontroversial answers to such questions as who owns, previously owned, and created the NFT, as well as which of the many copies is the original. Several types of digital objects can be associated to an NFT including photos, videos, and audio. Crucially, NFTs can be sold and traded, and are used to commodify digital as well as non-digital objects in different contexts, such as art, gaming, music and fashion. Started on Ethereum41, today NFTs are available on several other blockchains.Attributes and traits Attributes refer to human-readable characteristics of an NFT. In generative art, for example, they usually relate to visual properties of items. Attributes can take one among several values. For example, in the CryptoPunks collection, every item has the attribute “type” that can take one among the following traits: “Male”, “Female”, “Zombie”, “Ape” or “Alien”. CryptoPunks have also attributes that capture the presence of any accessory, such as earrings or bandanas. For the remainder of this study, we refer to the value taken by an attribute as the trait.Collections A collection is a group of NFTs whose associated digital items share common features. When minting an NFT, a creator can include the corresponding item within a collection. In generative art, for example, items of a collection are created by the same generative algorithm.Marketplaces Creators and collectors meet in online marketplaces to trade NFTs. The largest of these markets, OpenSea42, enables any creator to sell their NFTs and, at the moment of writing, it offers 44 million NFTs43. Other marketplaces feature a curated selection of creators . NFTs are auctioned on these marketplaces, where the NFT can be sold to the highest bidder or with a declining price, depending on the kind of auction. After an NFT is minted on a marketplace—i.e., it is converted into a digital asset on the blockchain—it can be put up for auction. Typically, the first transaction, from the creator of the NFT to the first user, is different in nature from the subsequent trades .49. The list of collections considered in this study can be found in the Supplementary Information. The dataset was built by considering all collections we could automatically match (by name) between rarity.tools17—a website dedicated to ranking collectible NFTs, also sometimes called Profile Picture NFT projects (PFP), by rarity—and the Opensea market. From the latter, we collected the release date, NFT traits and all sales concerning these collections that took place between January 23, 2018 and June 6, 2022. To avoid spurious effects, we only considered user-to-user transactions, where buyer and sellers are both aware of the precise identity of the traded NFT . In the following, we refer to the first user-to-user transaction as “primary” sale, and to all subsequent transactions as “secondary” sales. Where not specified, by “sales” we consider both primary and secondary sales.Our dataset includes 3,775,040 sales, taking place on the Ethereum blockchain, of 1,479,020 NFTs from 410 collections, including 61 of the top 100 collections by sales volume according to CoinMarketCapCollections in our dataset have on average 7554 NFTs. There is, however, wide heterogeneity across collections: the standard deviation of the distribution is 194.64, and the mode is 10,000 NFTs see Fig. a. The nuentclass1pt{minimaentclass1pt{minimaN NFTs, the trait rarity score, t shared by r NFTs is defined as:The rarity of a trait is quantified as the fraction of NFTs within a collection having this trait. This value is indicated on OpenSea’s sale page. For a collection containing NFT rarity score, To quantify the overall rarity of an NFT within a collection, we consider each trait independently and define the the NFT rarity rank, where the rarity rank of an NFT is given by the trait rarity rank of its rarest trait. This metric will allow us to quantify the effect of a rare trait on the market behaviour of an NFT, regardless of its other traits. Analyses based on the NFT rarity rank can be found in the Supplementary Information.Finally, we also consider 50.Further information on measuring NFT rarity, including a detailed discussion of the above measures, can be found inWe start by investigating the evolution of NFT sales in our dataset over time. We find that the interest in the collections remained stable until the end of 2020, then started to gain traction in 2021, especially in terms of available NFTs on the market . The number of primary sales grew from an average of 14 daily sales in January 2021 to 784 sales every day in March 2022, when the market peaked, implying a percentage growth of see Fig. . Similarsee Fig.  inset, aDifferent collections contributed to varying extents to the growth of the collectible NFT market. Figure 51.Collections are widely heterogeneous with respect to market properties. see Fig. a. FurtheWe quantify the distribution of rarity scores for items within the same collection. As an example, Fig. 52 (see SI for more details). We find that, among the distributions considered, For CryptoPunks, the median rarity score is 0.82, with only one of the 10,000 CryptoPunks having a rarity score above 75, whereas The same correlation analysis performed using the rarity rank confirms our results  In the following, we will focus on NFTs rarity score, because this metric takes into account all the traits associated with an NFT, and is therefore more suitable to quantify NFTs properties and rarity. All the following results are replicated using trait rarity rank as robustness check (see Supplementary Information section E.1).Our analysis indicates that the distribution of the rarity within a collection is heterogeneous, thus leading to a situation where rare NFTs are genuinely scarce on the marketplace. Notice that while this may seem trivial (“rare items are fewer than common items”), the distribution of traits rarity, and in turn their combination in single NFTs could in principle generate a wide range of distributions of NFT rarity, including homogeneous ones.To measure the relationship between rarity and market performance, we compute the rarity score of each NFT, and we split the assets into quantiles with respect to their rarity score to analyse collections individually. We then compare the median sale price across quantiles. We are using quantiles to ensure that NFTs within a collection will be evenly balanced between each bin, as to avoid having a collection skewing the results in the aggregated analysis, by having all of its NFTs concentrated in a single bin. For the individual collections analysis, NFTs are partitioned into twenty quantiles, whereas 100 quantiles are used when aggregating the collections together.p and the quantity (100-q), where q is the rarity quantile, is well described by a power law First, we consider the relation between market behaviour and rarity for three exemplar collections, CryptoPunks, Bored Ape Yacht Club, and World of Women see Fig. a–c. We oOn the other side, we find that rare NFTs are not sold as frequently as common ones on the marketplaces. By looking at the individual collections, we see that the average number of sales decreases as we increase the rarity of the NFTs we are considering see Fig. e–g. RegaIn order to check that this behaviour holds when considering a shorter time span within OpenSea’s lifetime, we performed the same analysis by considering only sales happening during the third quarter of 2021  and the fourth quarter as well . Our findings are also robust by considering the sale price in ETH rather than in USD , and by discarding the rarest and least rare NFTs from each collection . Moreover, we notice a similar pattern when quantifying the rarity of the NFTs with the NFT rarity rank instead of the NFT rarity score .R of the P(k) is the price that was paid for the NFT for its NFTs can be purchased and later put on sale again on the marketplace. An NFT owner is free to set an initial price to an auction, and to transfer the ownership of the NFT to the highest bidder. As such, NFTs which have been minted years ago, such as the CryptoPunks, can still be purchased on OpenSea. The results shown in Fig. q), where q is the rarity quantile, and the median return R is well described by a power law Figure see Fig.  inset. Tsee Fig. b. The frWe have quantified rarity in 410 NFT collections and analysed its effect on market performance. Rarity is a fundamental feature of NFTs belonging to a collection because (i) it allows users to categorise NFTs on the traditionally market-relevant axis of scarcity and (ii) it is based on human-readable, easy to identify, traits that creators assign to NFTs. We have found that the distribution of rarity is heterogeneous throughout the vast majority of collections. We have shown that rarity is positively correlated with the sale price and negatively correlated with the number of sales of an NFT, with the effect being stronger for the top 53, the design and evolutionary explanations could have fuelled one another over time, with creators embedding rarity out of imitation of successful pre-existent collections. In this perspective, our results could help to further improve the design of NFT collections.The finding that most rarity distributions are heavily heterogeneous, with few very rare NFTs, is interesting since in principle more homogeneous distributions would be possible. The ubiquitous nature of this pattern may indicate either that creators deliberately choose heterogeneous distributions (design perspective) or that heterogeneous distributions help make a collection successful and therefore are dominant in our sample of actively traded distributions (evolutionary perspective). While information on the rationale behind rarity distributions is hard to retrieve48. We found that while the impact of rarity is particularly strong for—and among—the rarest NFTs, which are thus genuinely non-fungible according to the market, its influence propagates to a large number of somehow rare NFTs  and different types of NFTs, assessing whether rarity has the same effects on other kinds of NFTs such as those related to gaming and the metaverse. Second, we used the rarity score to quantify the rarity of an NFT. While this method does take into account every trait associated with an NFT, it does not consider possible combined effects stemming from the combination of multiple traits . Future work could assess whether such second-order effects do play a role on the market performance of NFTs. Third, we considered traits as they are encoded in the NFT metadata and reported on rarity.tools, limiting the analysis to collections where such metadata are available and consistently recorded. Future work making use of computer vision techniques to extract human readable attributes from visual information of NFTs would yield to larger datasets and assess whether also less “official” visual traits, potentially shared by NFTs in multiple collections and where previously developed metrics might helpSupplementary Information.


In spite of considerable improvement in maternal and neonatal outcomes over the past decade in India, the current maternal mortality ratio and neonatal mortality rate are far from the Sustainable Development Goal targets due to suboptimal quality of maternity care. A package of interventions for improving quality of intrapartum and immediate postpartum care was co-designed with the Ministry of Health as the Dakshata program and implemented in public sector health facilities in selected districts in the state of Rajasthan of India since June 2015. This article describes the key strategies, interventions, results and challenges from four years of Dakshata program implementation.We have conducted secondary analysis of program data (government data) collected from 202 public facilities across 20 districts of Rajasthan state. The data collected between June–August 2015 (baseline) and the data collected between May-August 2019 (latest) were analyzed. The data sources included: facility assessments, service statistics, monthly progress reports.During the period of program implementation, there were 17,94,249 deliveries accounting for 70% of institutional deliveries in intervention districts. As a result of the intervention, there was a notable increase in competency of health care providers, availability of essential resources, achievement of labour room standards and adherence to evidence-based clinical standards. We also observed reductions in the proportion of referrals for pre-eclampsia/eclampsia, postpartum hemorrhage and neonatal asphyxia by 11, 8 and 3 percentage points respectively. Similarly, data revealed a reduction in stillbirth rates in Dakshata intervention facilities (19.3 vs 15.3) compared to non-Dakshata facilities (21.8 vs 18).Our experience and findings indicate that the quality of intrapartum and immediate postpartum care can be improved in low- and middle-income countries with the approach presented in this paper.The online version contains supplementary material available at 10.1186/s12884-022-04888-5. One of the Sustainable Development Goals (SDG) is to reach fewer than 70 maternal deaths per 100,000 live births and neonatal deaths fewer than 12 per 1,000 live births globally by 2030  are far As a result of various national schemes –7, ratesTo address these issues, Jhpiego, in collaboration with the Government of Rajasthan and with funding support from Children’s Investment Fund Foundation (CIFF), implemented an intrapartum and immediate postpartum quality improvement initiative . The WorIn this article, we describe the process of implementing Dakshata initiative in selected public hospitals in Rajasthan state of India. We report the key strategies, interventions, results and challenges from four years of Dakshata program implementation. To our knowledge, this is one of the largest efforts to implement and evaluate a quality improvement initiative in a real-world setting in low- to middle-income countries.Rajasthan is the largest state in western India, with 84% institutional deliveries, out of which 63% occur in public facilities; the maternal mortality ratio is 164 per 100,000 live births .As a strategic decision Table , the DakThe first phase of the program was implemented in 147 facilities in 13 districts, beginning in 2015. In a second phase in 2017, 55 facilities in seven more districts were targeted. In October 2018, the Government of Rajasthan scaled up the program across all 34 districts in the state . Periodic assessments and refreshment trainings were provided as needed.Overall, nine training of trainers for the duration of 5 days and 279 trainings for health care providers for the duration of 3 days with 10–15 people per group were conducted. The tools used for knowledge, skills and competency were as per Dakshata package . The skiWe conducted secondary analysis of program data (government data) collected from 202 public facilities across 20 districts of Rajasthan state  reviewed the activities and determined them to be not human subjects research and thus not requiring IRB oversight (IRB No: 00005529).The following tools used for data collection were approved by Government of India as part of monitoring activities under Dakshata program .For case records, 50% or more of checked case records should indicate that the practice is performed at the facility to be considered as “yes”For providers’ interviews, 100% provider(s) interviewed should correctly respond forthe verification criteria to be considered as “yes”For mothers’ interviews, 50% or more of mothers should provide a response indicating that the practice is being performed by providersA rapid assessment was conducted by program officers with medical backgrounds in all program sites before roll out of Dakshata program. The assessment took 4–6 h to complete. The same tool was used for quarterly periodic assessments Table . All theFor a practice to be considered as “yes” in the response column, all the verification criteria under that practice should have a score of “yes” in the score column.A standard will be scored either 0 or 1 depending on the responses. If the responses of all practices performed under a standard are “yes”, then the standard will score 1 point. If one or more responses for practices under a standard is “no”, the standard scores 0 points.This comprised the aggregate data submitted by public health facilities on key service delivery indicators to the Pregnancy, Child Tracking & Health Services Management System (PCTS) of Government of Rajasthan.Maternal and Newborn Complications Identification and Referral Monitoring System. Since, there was no formal mechanism in the government systems to monitor childbirth and newborn related complications and management, a monthly complication reporting format was introduced in all intervention facilities. The complication reporting format captured data on key maternal and newborn health indicators from the labour room, postpartum ward, Sick Newborn Care Unit, admissions and discharge department of the facility. This format captured data on total deliveries, type of deliveries, fresh stillbirths, preterm births, maternal and neonatal death, maternal complications , neonatal complications , and refer-in and refer-out data for maternal and neonatal complications. One nodal person, preferably a labour room staff, was selected from each intervention facility to act as the key contact person for this initiative. Data was validated regularly by the program team.In order to ensure high quality of data, all program officers involved in data collection were trained before initiating data collection. Additionally, the program team conducted routine data quality checks using a data quality assurance toolkit .Data from periodic assessments were entered in CS Pro  and dashIn this manuscript, we have used data from June 2015 till December 2019 for competency of providers to perform evidence-based practices, availability of essential resources, labour room standards, adherence to evidence-based clinical standards, as well as the identification and management of maternal and neonatal complications. All these data were collected by Jhpiego staff who have medical background with several years of experience in implementation of maternal and child health programs in the state of Rajasthan. For stillbirths, we used PCTS data from March 2015 till March 2020 as it was reported in the Government of Rajasthan’s health management information system (PCTS).During the program implementation period there were 17,94,249 deliveries, this accounts for 70% institutional deliveries in intervention districts. The staff in our intervention facilities were able to identify 37,565 maternal and 18,588 neonatal complications and referred 15,359 maternal and 7,416 neonatal complications.Overall, 3,757 providers were trained from 525 facilities across Rajasthan state; providers included 77% staff nurses , 21% doctors (780) and ~ 2% lady health visitors and other staff. As a result of these trainings, there was a considerable increase in competency of health care providers in active management of third stage of labour (5% vs 92%), newborn resuscitation (3% vs 92%), management of antenatal complications (9% vs 85%) and management of postnatal complications (19% vs 77%).The availability of all 26 essential supplies and commodities in the labour room and postpartum wards significantly improved from 73 to 96% during program implementation Table S. At the The analysis of labour room standards revealed that 29% of the intervention facilities met all 7 standards at the beginning of the program, compared to 71% of facilities in the latest assessment. It was also observed that the average number of labour room standards met increased from 2 to 5 during the course of the program  Fig. .Fig. 3TrThe proportion of postpartum haemorrhage referrals decreased by 8 percentage points (from 32.7% in January-December 2017 to 24.7% in January-December 2019) Fig. .Fig. 4TrSimilarly, PCTS data revealed a relatively greater reduction in stillbirth rates at Dakshata intervention facilities (19.3 vs 15.3) compared to non Dakshata facilities (21.8 vs 18) Fig. .Fig. 6TrOur findings are indicative that capacity building, mentorship support, focusing on high delivery load facilities, utilization of contextualized SCC, data-driven decision-making and government ownership resulted in improved service delivery.Global evidence suggests that programs that only focus on capacity building of health care providers or targeting supply availability are insufficient to improve quality of care and outcomes . It has Capacity building of service providers to perform evidence-based practices was one of the main pillars of the Dakshata program. The training package included highly interactive “skills and drills” and “team training” approaches. The studies conducted across the globe indicates that this approach improves communication, coordination and cooperation among various health care cadre  and incrThe trainings were followed by mentorship activities for ensuring transfer of learnings into practice and availability of essential supplies and commodities. Previous studies conducted in Rajasthan , Uttar PEven structured MSVs package are not sufficient as providers have different learning needs and variable knowledge retention power. Besides, some of the practices are linked with providers’ perception and motivation to adhere to them. It is unrealistic to assume that providers’ behaviors, that developed during years of service tenure, will be changed in terms of adherence to practices with only capacity building and a few mentoring and support visits. Studies have demonstrated waning knowledge retention by 6 months following completion of the neonatal resuscitation program course , 35. ConAs a part of improving evidence-based decision making, a standardized labour room case sheet was developed based on existing records in the facilities. However, as the program advanced, it became important to have data on process of care and data visualization (dashboards) for effective program implementation. Therefore, program team initiated the development of the Maternity Wing Management Information System (MWMIS) in which client case records were digitized, thus generating dashboards for district and state-level officials which could be utilized for effective program review. However, while MWMIS was useful for monitoring and tracking of labour room practices and outcomes, it was not serving the purpose of providing real-time data for action. Therefore, Jhpiego worked with donors to develop an Android-based clinical decision support system. MWMIS has been replaced by a real-time “Prasav Watch” (Labor Watch) application across the entire state of Rajasthan.The Government of Rajasthan scaled up Jhpiego’s approach for sustaining quality improvement activities and hired dedicated Dakshata mentors. An induction package for Dakshata mentors were developed and a mechanism of 15 days mandatory internship for all newly joined mentors were ensured. However, it was challenging to monitor these mentors and track their progress. In order to sustain the quality improvement efforts in a comprehensive manner, an Android-based mobile application (the Dakshata Mentor App) was developed for mentors to enter the data of each facility visit, under domains such as training status, resource availability, labour room environment, adherence to practices and topics for which mentoring was provided. The data from this app are being used by the state for rapid and effective real-time monitoring of labour rooms.Government ownership is not only critical for ensuring the sustainability of the program but also one of the key driving factors for effective continuity of the program. The program team engaged with government officials at all levels—facility, district and state level. After completion of any activity, whether it was an MSV or a periodic assessment, the team worked with facility in-charges to do a bottleneck analysis and developed an action plan. Some of the issues , which could not be addressed at the facility level, were discussed during district review meetings and addressed. Since the initiation of the program, the state has budgeted for all program activities in the annual project implementation plans under the National Health Mission, for training, strengthening of labour room infrastructure, procurement of essential resources, as well as recruiting dedicated Dakshata mentors to sustain the program in respective districts. The state conducted regular review meetings with facility in-charges and district-level officials in order to ensure that identified gaps are being addressed in a timely manner and to hold poor-performing facilities accountable. Thus, the steadfast commitment of the state has been instrumental in the smooth implementation of the program.Additionally, based on independent midline evaluation results and recommendations, key corrective actions were taken that resulted in considerable improvement Table .Table 4RIt is important to mention that Dakshata program targeted 202 (19%) high delivery load public facilities. This approach supported improving care provided to 70% of deliveries taking place in public facilities of selected districts in a short time period, thereby contributing to better maternal and neonatal outcomes.The multidisciplinary nature of the labour rooms, the complexity of task involved and lack of tested mechanisms to track measurable processes and outcomes possess challenges . DespiteFrequent rotation of trained human resources from labour rooms to other wards of the facilities led to another challenge of ensuring trained and adequately skilled staff at labour room. This required extra efforts by the mentor to train newly transferred staff on the clinical guidelines and processes in the labour room. In order to minimize this hindrance, the state has issued directives on the non-rotation of trained competent staff in the intervention facilities. Program team also developed a nurse duty roster in MWMIS to allow state officials to track the status of trained human resources in labour rooms. Additionally, the team worked with the state government to identify the deficiency in availability of staff, as per norms, and address them. Based on the requirement, state initiated the process of recruiting additional nursing staff.The Government of Rajasthan worked to streamline the data recording process by standardizing the labour room case sheet. However, lack of awareness among nursing staff regarding importance of proper data recording and shortage of nursing staff at labour room were major hindrance in getting quality data to guide decision-making processes. To tackle this issue, the MWMIS tool was developed. Additionally, suboptimal entry of case sheets data into MWMIS by the data entry operators was another bottleneck. As these issues can affect the utilization of this data for decision-making, the state has been focused on orienting the service providers on ensuring the completeness of case sheets and it has been focused on tracking the performance of the data entry operators.Some of the essential practices showed poor adherence, which we termed them as sticky practices, despite repeated mentorship visits, including hand hygiene, plotting of partograph, newborn resuscitation, post neonatal monitoring and counselling. These sticky practices varied across the facilities. Facilities with higher delivery loads and acute shortage of staff are more likely to omit most of these practices. Practices which showed immediate gratification, in terms of life saved or complication averted, were quickly adopt by providers. On the other hand, practice which do not show any immediate harm or benefits, like vital measurements, are difficult to achieve. There are certain practices for which there are not ample opportunities to practice (e.g. newborn resuscitation) that are again difficult to demonstrate. Most importantly, practices which providers have been observing since their initial days are difficult to stop, such as augmentation of labour, and will require focused efforts and close supervision from the administrative authorities. There are many determinants of service providers’ adherence to evidence-based practices, such as knowledge about the importance of particular practices, providers’ attitudes and personal motivations and immediate results observed after performing the practices.Being a government-led initiative, the implementation of Dakshata program requires ownership and accountability at all levels of the health system. Starting from district-level sensitization meeting to organizing district-/state-level review meeting, program team worked to bring ownership at all levels. Despite best efforts, some of the facilities did not show expected improvement. At the end of each periodic assessment, the team did bottleneck analysis and developed an action plan which pointed towards lack of ownership by facility in-charges as an important factor for poor performance of some facilities. To address this issue, the program team identified a champion from the existing staff working at the facility level based on their ability and motivation to bring changes and communication skills. These champions were later designated as the nodal person for the Dakshata program at their facility and have been a key step forward in this regard. Nodal person helped in ensuring supplies at point of use and bring infrastructural changes to labour rooms.The Dakshata program succeeded in improving the quality of care provided during labour and immediately after delivery in the state of Rajasthan. Despite this intervention being scaled up across the country, there is no systematic analysis of weakness, opportunities and the learnings from different states across India. It is, therefore, imperative to conduct assessments and data reviews to guide future programming for improving maternal and neonatal outcomes.Additional file1: Table S1. The availability of resources in labour room and postpartum wards (n=202). Table S2. Labour room standards (n=202). Table S3. Providers’ adherence to key clinical standards.


The aim of the Maternal Infant Support Worker (MiSW) pilot program was to implement a virtual training program for lay maternal–infant health providers in remote First Nations communities in Northwestern Ontario, Canada.The MiSW pilot program was administered jointly by a community college and a university and consisted of a 20‐week virtual course followed by a 9‐month mentored work placement in the community.The MiSW pilot program was delivered successfully; 11 of 13 participants received a certificate from a community college. MiSWs provided culturally and linguistically appropriate care to women, infants, and families in their respective communities. MiSWs provided doula support in their communities—a first for our region since the policy of forced evacuation for birth was implemented. MiSWs developed a community of practice for ongoing education, as well as to support each other in their work.The MiSW pilot program demonstrated that it is possible to provide a virtual training program and then provide continued virtual mentorship as the participants work in their First Nations communities. By prioritizing Indigenous voices above those of the research team, we were able to gain the trust of the MiSWs and maintain engagement with communities. The Maternal Infant Support Worker pilot program successfully implemented a virtual training program for lay maternal–infant workers living in remote communities. These were moments of celebration and provided the mother and the newborn with invaluable community support.To exacerbate matters, Indigenous communities in the region began experiencing an epidemic of opioid misuse approximately 15 years ago.The Maternal Infant Support Worker (MiSW) pilot program was a community‐based intervention that aimed to increase the health system's capacity to provide integrated maternity, mental health, and addiction care to pregnant and parenting women affected by opioids, living in rural and remote First Nations communities in Northwestern Ontario, Canada. This article describes the implementation of the MiSW pilot program and the co‐creation of the pilot program evaluation.22.1®The MiSW pilot program was carried out using the OCAP2.2Indigenous grassroots theory and the sweetgrass story weaving methodology described by Wabie,2.3https://www.youtube.com/watch?v=bK_bzr2aJqs). At that time, funding was only secured for curriculum development. Funding to implement the MiSW pilot program was obtained in 2018, with additional collaboration from the Northern Ontario School of Medicine and Lakehead University , the Sioux Lookout Meno Ya Win Health Centre, and Confederation College  was undertaken Table . The firPrior to the initiation of the MiSW pilot program, the research team had informal conversations with health directors and administrators in the SLAAMB communities. Three health directors were either themselves Indigenous midwives until the policy of forced evacuation for birth ended Indigenous midwifery in the region or had Indigenous midwives in their families. There was an overwhelming positive response for this type of program. Only one health director provided words of caution, that, although this type of program is a step in the right direction, it is not a replacement for traditional knowledge systems around pregnancy and infant care, traditional skills around birth, and traditional ways of sharing knowledge.Since the initiation of the MiSW pilot program in 2013, Canada's relationship with Indigenous peoples has been evolving, guided by the report of the Truth and Reconciliation Conciliation Commission. As a result, a review of the curriculum was undertaken. Of the 40 videos that were originally created for the program, only five contained Indigenous content. Curriculum items that were no longer deemed appropriate were removed and replaced by other resources, including the addition of more Anishnaabe‐ and First Nations‐based content Table , at the 33.1Two cohorts of six individuals participated in the pilot program Figure , Table 7Although the inclusion criteria contained educational attainment, we did not collect data on this because the intent of the pilot program was to validate the skills and knowledge that the individuals had as recognized by their community. Through discussions with the participants, it was clear that most participants had not completed high school and, therefore, they had been nominated by their communities based on lived experience.Nine of the 13 participants spoke Ojibway or Ojicree as their first language. Through observation we identified a few participants who probably had low literacy in English. This issue was never addressed explicitly. Rather, we adjusted the presentation of materials to meet their learning needs. The other participants also began translating for their colleagues or providing their interpretation of the written information, which stimulated discussion and allowed for inclusion of everyone in the cohort. Weekly journaling was a part of reflective practice in the curriculum. However, when literacy concerns were identified, this requirement was replaced by weekly individual communication with the course instructor.Additional factors competing for the attention of participants during the pilot were the demands of their jobs and personal or community emergencies. The course instructor was available for individual tutorials when needed, regardless of the reason. Although there was a decline in participation in the virtual group meetings as the cohorts progressed, the course instructor had contact with all participants individually on a weekly basis, except in circumstances of illness or emergency.In terms of overall participation, one participant in the first cohort withdrew from the pilot program for personal reasons. The nominating community put forward a replacement. After discussions with community representatives, it was determined that an accelerated catch‐up program could be offered and the request was accommodated. One participant in the second cohort missed the initial in‐person gathering and then did not participate in group or individual meetings. Efforts to increase engagement were unsuccessful. At the 13‐week mark, the participant was too far behind to successfully complete the pilot program. After discussions, the participant withdrew from the pilot program.The remainder of the participants graduated from the pilot program and were gifted a braid of sweetgrass upon graduation. The research team underestimated the significance that graduation held for the participants, their families, and the communities. The ceremonies received widespread attention in local and regional media, as well as thousands of impressions on social media, including tweets from the Minister of Indigenous Services Canada.During the final in‐person week with the first cohort, one half‐day was dedicated to developing evaluation materials. For the mentored practice phase, the participants recommended continuing reflective practice using oral documentation. Weekly visit logs and touchpoint logs that were largely checkbox based were also developed and approved by the participants. For the overall pilot evaluation, the participants recommended interview‐based tools to facilitate data collection. Key informant interview guides were developed for the course instructor, community administrators, mothers, and MiSWs.3.2Following graduation, the MiSWs continued to work in their respective communities and received mentorship for 9 months in the form of weekly virtual meetings that had two aims: developing case management skills and addressing the specific learning needs of the participant. Table Among the many activities during the mentored practice phase Table , the MiSAn MiSW in community A was contacted via a mobile messaging app by a woman in distress with a concealed pregnancy in community B. The MiSW sought advice from her colleagues while she supported the woman and diagnosed labor and ruptured membranes. The MiSW encouraged the woman to go to the nursing station, remained with her during labor and delivery at the nursing station. The woman and her baby were transferred by air to the hospital after delivery. The MiSW got back in touch with the woman at the hospital to provide ongoing support and again when she was discharged home to her community.Below is an example that illustrates the role and impact of the MiSWs in the community that unfolded over a number of days, as told to the course instructor.The MiSWs developed more confidence in themselves in the safe and collegial space created during the mentored practice phase. They began to rely less on the course instructor and more on each other for support and information. The MiSWs started an online “community of practice” for themselves that continues to this day as a network for support, information, and sharing of professional development opportunities.4The MiSW pilot program faced four major challenges. First, restructuring at Confederation College led to a personnel change that disrupted the relationship between the research team and the participants during the training phase for the first cohort. Second, following a change in government in 2018, the grant scheme funding the pilot project was terminated 1 week after the second cohort began the training phase. Funds were reallocated at SLAAMB and from other research grants, enabling the second cohort to continue.Third, since the start of the COVID‐19 pandemic in 2020, all in‐person research was halted by Lakehead University, and all Indigenous communities restricted access to non‐community members. Despite this, the course instructor continued to mentor the MiSWs and help them translate their skills to new roles in the local pandemic response.Finally, despite our efforts to co‐create evaluation materials for the mentored practice phase, the participants in both cohorts did not complete the logs or the weekly self‐reflections. The research team wondered if the logs represented an additional documentation burden, but a clear response to this question was not obtained. In keeping with Indigenous grass roots theory, the decision was made to abandon the log‐based evaluation in favor of centering the stories of the MiSWs themselves. They had ongoing dialogue with the course instructor regarding the type of cases they were seeing, as well as their reflections on their management of clients. The course instructor, with the consent of the participants in both cohorts, kept notes of the encounters.5The overall aim of the MiSW pilot program—to implement a virtual training program for lay maternal–infant health providers in remote First Nations communities and to support them through the first 9 months following graduation—was achieved. By prioritizing Indigenous voices above those of the research team, we were able to gain the trust of the MiSWs and maintain engagement with communities. Our next steps will be to complete the overall pilot program evaluation to assess the impact of the MiSWs in their communities.The authors have no conflicts of interest.Under the lead of NJ, the authors LB, MT, AR, and CM contributed to the design of the study; LT and RT contributed to data collection and analysis. All authors contributed to manuscript writing and approved the final draft of the manuscript.


Candida albicans and Streptococcus mutans biofilm for 72 h and then disinfected with either of the denture cleansers . Distilled water served as the control group. The colony-forming units of the microorganisms were calculated, followed by post-treatment surface roughness. Data were statistically analyzed using one-way ANOVA, paired t-test, and post hoc Tukey HSD test (α = 0.05). Among the denture cleansers, 2% Chlorhexidine gluconate, 0.5% sodium hypochlorite, and 1% sodium hypochlorite had the best cleansing effect on the resin discs and demonstrated zero growth of colonies for both the species. Comparing the material groups, the 3D-processed discs showed higher colony-forming units followed by the conventional and CAD/CAM milled group. The highest surface roughness was demonstrated by the 3D-printed discs (0.690 ± 0.08 μm), followed by the conventional (0.493 ± 0.11 μm) and the milled groups (0.301 ± 0.08 μm). The tested chemical denture cleansers affected the Candida albicans and Streptococcus mutans adhesion compared to control discs immersed in distilled water. The clinician may recommend to their patient to use 2% chlorhexidine gluconate for the disinfection of CAD/CAM PMMA denture base materials.This study assessed the efficacy of five denture cleansers on the microbial adherence and surface topography of conventional and CAD/CAM denture base resins. Acrylic resin discs were fabricated using conventional, milling, and 3D printing methods (N = 180). The discs were contaminated with dual species of  Despite the technological advances in dentistry, a complete denture (CD) is still the primary treatment option for the rehabilitation of the edentulous dental arch . PolymetIn recent years, the application of computer-assisted design and computer-assisted manufacturing (CAD/CAM) technology for the fabrication of CDs has significantly expanded ,9,10,11.Candida albicans infections [Streptococcus mutans and Staphylococcus aureus, can also cause denture stomatitis rather than C. albicans alone [Denture stomatitis, a multifactorial oral pathological condition, is induced by biofilm that accumulates on the tissues and denture surface and is marked by varying degrees of erythema, bleeding, and halitosis ,15. The fections ,17. Howens alone .Denture hygiene maintenance involves either mechanical or chemical, or a combination of both, methods ,20. MechAn ideal chemical denture cleanser should inhibit or reduce the accumulation of biofilms; possess antifungal and antibacterial activity; have a pleasant odor; and be inexpensive, easy to use, and non-toxic ,25,26,27Roughness on the surface of restorative and prosthetic materials considerably interferes with material properties, decreases their longevity ,29, and Therefore, this study aimed to investigate the efficacy of five denture cleansers on the microbial adherence and surface topography of conventional, milled, and 3D-printed denture base resins. The null hypothesis stated is that the tested denture cleansers would have a similar effect on the microbial adherence and surface topography of conventional, milled, and 3D-printed denture base resins.PMMA acrylic resin discs (Ø10 × 3-mm) were fabricated using conventional, CAD/CAM milling, and 3D printing methods (N = 180) A. Table ® selection, Ivoclar Vivadent, Schaan, Liechtenstein).The discs of conventional acrylic resin  were fabricated using the lost-wax technique . For theThe 3D-printed discs were fabricated using the same digital file used for milling. The STL file was uploaded to the CAM software  connected to a Mask Stereolithography (MYLA) 3D printer . The photopolymerized liquid resin  was used to print the disc layer-by-layer at a 0-degree direction and at a thickness of 50 µm using the MSLA technique . Once thFor standardization purposes, a single investigator performed the finishing and polishing of all the acrylic discs. The discs were finished with a tungsten carbide bur  at 300 rpm under water coolant and then polished in a compact polishing unit  using a wet rag wheel and pumice slurry at high speed for 60 s. The final gloss of the disc was obtained using a dry and clean rag buff wheel and zircate prophy paste . The discs were ultrasonically cleaned in distilled water for 5 min and dried with absorbent paper. Next, the discs were randomly allocated to 6 groups using the lottery method (n = 10).2 field of view, a scan speed of 1×, and a 0.1 mm/s stage speed. The disc was scanned at 5 equidistant areas, and the mean of these readings correlates to that particular disc’s surface roughness and is expressed as Ra (μm).The surface roughness of the acrylic resin disc was assessed using an optical non-contact profilometer  assembled with the atomic force microscopy (AFM) module and Vision 64  proprietary software . The meaC. albicans and S. mutans. The C. albicans strain (ATCC 10231) and S. mutans strain (ATCC 25175) were harvested from a fresh culture and inoculated into 5 mL of brain heart infusion  broth and incubated at 37 °C for 48 h. The aftermath cell pellets were washed twice with phosphate-buffered saline  for 2 s to remove non-adherent cells. After dilution with PBS, the final dual-spp cell suspension was prepared to a concentration of 1 × 10−3 cells/mL. The discs were placed in petri dishes  containing 1 mL of BHI broth and 12.5 μL of prepared cell suspension. The discs were incubated at 37 °C for 72 h at 75 rpm to permit biofilm formation (adhesion period).Biofilm assays were performed with dual-spp biofilms of Five denture cleansers—Fittydent cleansing tablets , 0.2% Chlorhexidine gluconate (CHG) , 2% CHG , 0.5% sodium hypochlorite (NaOCl), and 1% NaOCl —were prepared according to the manufacturer’s instructions. The discs were immersed in 2 mL of prepared denture cleanser solution in accordance with previous studies, and then Fittydent solution for 5 min , 0.2% CHThe adherent microbial cells were dislodged from the surfaces of the discs in 2 mL of distilled water by vortexing for 1 min using a super mixer. The cell suspension was diluted to 4 by transferring 100 μL of the cell suspension to 900 μL of distilled water each time. The third and fourth dilutions were then plated on Sabouraud Dextrose Agar  medium and incubated at 37 °C for 24 to 72 h under aerobic conditions. After 72 h of incubation, the number of colonies formed was counted for each dilution and expressed as a colony-forming unit (CFU)/mL .The cell viability of the microorganism was assessed using Eclipse TE2000 confocal laser scanning microscope (CLSM) . The discs with adherent biofilm were washed thrice with PBS and stained with Cell Tracker™ green, actin red, and Hoechst 33342 blue dyes  for 1 h. Post-staining images of the discs were acquired using an Argon laser , Melville, NY, USA) at 488/520–530 nm (ex/em) for Cell Tracker™ Green and a HeNe laser at 633/650 nm (ex/em) for actin red. The counterstained nucleus was detected using a UV laser at 350/460 nm (ex/em). The specimens were observed using a 4× lens, and images were acquired using an oil immersion objective. Five random stacks spanning the entire surface of the disc with a step size of 2 µm were acquired for each representative specimen.A representative disc from each group was subjected to qualitative analysis using a scanning electron microscope  to determine the pattern of microbial adhesion or growth on the surface. The representative disc after SEM analysis was not counted for further microbiological analysis. Before image processing, the disc was gold sputter-coated for 1 min using a coating machine . The SEM images were acquired at a magnification of 5000×, 15 kV, and a working distance of 10 mm. In both CSLM and SEM analysis, the images of a contaminated denture surface of the negative control group were used as a reference for comparison.The data analysis was performed using Statistical Package for Social Sciences (SPSS) . One-way ANOVA was used to describe the biofilm isolate adhesion values (CFU) and surface roughness of the conventional, milled, and 3D-printed discs. A paired t-test was used to compare the surface roughness of each material group before and after denture cleanser treatment. A post hoc Tukey HSD test was used to find any significant interactions between the material groups (α = 0.05).3 CFU/mL) of C. albicans and S. mutans after denture cleanser treatment. Among the denture cleansers evaluated, 2% CHG, 0.5% NaOCl, and 1% NaOCl had the best cleansing effect on the resin discs. The results of the CFU/mL for the discs treated with the above denture cleanser solution were zero for both the spp.C. albicans spp, and the difference in the number of CFU/mL between the different material groups was statistically significant (p = 0.003). For the S. mutans spp, the discs immersed in water showed high CFU/mL compared to the discs immersed in cleansing solutions; however, there was no significant difference in CFU/mL between the material groups (p = 0.29). The CFU/mL of the discs treated with Fittydent solution showed a statistically significant difference between the material groups (p = 0.017). In comparison to the Fittydent group, the discs treated with 0.2% CHG demonstrated higher CFU/mL for the conventional and milled group and lower CFU/mL for the 3D-printed discs.The discs treated with Fittydent solution showed high CFU/mL for Comparing the CFU/mL of the material groups, the 3D-processed discs showed higher values followed by the conventional group. The CAD/CAM-milled discs demonstrated the lowest CFU/mL of all the material groups.p < 0.05). The highest Ra was demonstrated by the 3D-printed discs (0.690 ± 0.08 μm), followed by the conventional (0.493 ± 0.11 μm) and the milled groups (0.301 ± 0.08 μm). The comparison between the surface-treated discs of the conventional and milled groups showed a significant difference in Ra for the denture cleansers used .The SEM micrographs demonstrating the microbial adherence to the disc surface for all the groups are presented in To the best of the authors’ knowledge, there are no previous studies which evaluated the efficacy of denture cleansers on the microbial adherence and surface topography of CAD/CAM-milled and 3D-printed PMMA resins. The null hypothesis was partially rejected in light of the study outcomes, as the tested denture cleansers did not show a similar effect on the microbial adherence and surface topography of the tested denture base resins.C. albicans and S. mutans were employed based on the pathogenic potential or representational significance of the microorganisms for antimicrobial-effectiveness evaluation studies. C. albicans is associated with the occurrence of denture stomatitis in conjunction with other factors such as denture hygiene, trauma, and systemic diseases. Therefore, research in dentistry focuses on C. albicans as a role in stomatitis as well as a concern with cross-infection. S. mutans is a normal component of the oral microbiota; however, the presence of this microbe at the infection site could be interpreted as a contamination indicator [Denture stomatitis is a common problem affecting 15–70% of denture wearers . In the ndicator .C. albicans and S. mutans from the denture surface. On the contrary, CHG is considered the best chemical denture cleanser for controlling dental biofilm and preventing denture stomatitis. It can bind to oral surfaces with a gradual release, effectively limiting the initial adherence of fungus and other microbes and, as a result, minimizing biofilm formation [A short-term chemical disinfection protocol helps treat denture stomatitis. Among the several chemical denture cleansers available on the market, NaOCl and CHG chemical solutions are widely used , althougormation . Chlorheormation .C. albicans and S. mutans cell adhesion. The CFU/mL of the PMMA discs (irrespective of the processing method) treated with these solutions was low for both the spp, indicating the best denture-cleansing effect, and thus agreeing with previous studies [C. albicans from 3D-printed discs and S. mutans from either of the disc surfaces. This outcome is in disagreement with the findings of de Andrade et al. [The outcome of this study demonstrated that short-term chemical disinfection protocols using 0.5% and 1% NaOCl and 2% CHG effectively reduced the  studies ,29,39,42e et al.  where the et al.  showed aS. mutans adhesion was unaffected, whereas C. albicans adhesion increased on milled and 3D-printed oral splints compared to traditional thermoforming and pressing. Similarly, after 16 h of incubation, Fiore et al. [Comparing the CFU/mL of the discs processed using different techniques, the 3D-processed discs showed higher values followed by the conventional group. The milled discs demonstrated a lower CFU/mL of all the material groups. This outcome supports the predominance of CAD/CAM milling over 3D printing, as also concluded by previous studies ,12. On te et al.  found noSurface roughness plays a significant role in microbial colonization on denture surfaces ,46. The Despite a similar finishing and polishing by a single operator, the PMMA material groups exhibited roughness values above the threshold values except for the milled PMMA discs at baseline. After treatment, all the PMMA material groups showed a significant increase in roughness. However, the milled discs exhibited Ra values below the threshold limit except for the samples immersed in 1% NaOCl. The specimens stored in 2% CHG showed the lowest roughness values among the denture cleansers used except for the 3D-printed group, where it showed values non-significantly higher than discs immersed in NaOCl. Although previous studies have compared the surface roughness between the three processing methods ,45, the Although the purpose of the current in vitro investigation was to mimic a natural intraoral environment, it has some limitations. The standard methodological approach may not be logical in in vivo conditions. The antimicrobial property of saliva could contribute to the decreased adhesion of microorganisms, which was not considered in the present study. Depending on the type of denture-cleanser solution, the immersion period varies. However, for individuals who practice good denture hygiene frequently, the actual immersion time may differ. Future studies should focus on evaluating the role of an acquired salivary pellicle in microbial adhesion and the efficacy of disinfection protocols of the tested CAD/CAM materials. In addition, the tested parameters should be evaluated in an in vivo model to clearly understand the behavior of these materials and denture cleansers in an actual clinical environment.Candida albicans biofilm and Streptococcus mutans adhesion; however, all denture cleansers significantly increased the surface roughness of the PMMA discs. Irrespective of the processing method, the results showed a high antimicrobial effect of 2% CHG, 0.5%, and 1% NaOCl cleansers. However, considering the roughness parameter, 2% CHG was a more promising denture cleanser for the disinfection of CAD/CAM-processed dentures. The clinician may recommend to their patient to use 2% chlorhexidine gluconate for the disinfection of CAD/CAM PMMA denture base materials.Considering the methodological approach and the limitations, the tested chemical denture-cleanser solutions affected